Title of Invention	A PROCESS FOR THE PREPARATION OF ORGANOPHILIC CLAY USEFUL AS GELLANTS FOR MAKING VISCOUS ORGANIC SYSTEMS.
Abstract	A process for the preparation of organophilie clay useful as gellants for making viscous organic systems by dispersing 2 to 3 weight percent of raw smectite clay in de mineralized water under stirring by known method, purifying the said dispersed clay slurry by known methods to obtain cation exchange capacity of 60 miliequivalent per 100 g clay and a water swelling capacity of 20 cc:, converting the purified bentonite clay slurry to homo ionic form by reacting with concentrated alkali metal inorganic salt solution or hydrochloric acid or by passing the clay slurry through the desired cationic form of ion exchange resin; preparing a solution of quaternary ammonium salt in de mineralized water at 70°equivalent to the cation exchange capacity of the purified clay: adding the quaternary ammonium salt solution to the homoionic clay slurry at room temperature under constant agitation, allowing the reaction mixture to age under stirring to obtained flocculated clay, separating the flocculated clay by known methods, to obtain wet cake of organophilic clay; drying the wet cake in an air circulated oven, while maintaining the temperature at 65 °Celsius, until the free moisture is percent; pulverizing the dry granules in a steel hammer mill to obtain a fine powder.

Title of Invention

A PROCESS FOR THE PREPARATION OF ORGANOPHILIC CLAY USEFUL AS GELLANTS FOR MAKING VISCOUS ORGANIC SYSTEMS.

Abstract

A process for the preparation of organophilie clay useful as gellants for making viscous organic systems by dispersing 2 to 3 weight percent of raw smectite clay in de mineralized water under stirring by known method, purifying the said dispersed clay slurry by known methods to obtain cation exchange capacity of 60 miliequivalent per 100 g clay and a water swelling capacity of 20 cc:, converting the purified bentonite clay slurry to homo ionic form by reacting with concentrated alkali metal inorganic salt solution or hydrochloric acid or by passing the clay slurry through the desired cationic form of ion exchange resin; preparing a solution of quaternary ammonium salt in de mineralized water at 70°equivalent to the cation exchange capacity of the purified clay: adding the quaternary ammonium salt solution to the homoionic clay slurry at room temperature under constant agitation, allowing the reaction mixture to age under stirring to obtained flocculated clay, separating the flocculated clay by known methods, to obtain wet cake of organophilic clay; drying the wet cake in an air circulated oven, while maintaining the temperature at 65 °Celsius, until the free moisture is percent; pulverizing the dry granules in a steel hammer mill to obtain a fine powder.

Full Text	The present invention relates to a process for the preparation of improved organophilic clay useful as gellants for making viscous organic systems. In the field of chemical technology this invention relates to the modified clay complexes and to a method of preparing them. More particular!}' this invention relates to the ion-exchange process for the preparation of hydrophobia clay complexes which are compatible with organic liquids / mineral oils in contrast to an unmodified hydrophilic clay that is easily dispersible in water. The preparation of organpclay complexes that are compatible with organic liquids has been known for some time. A naturally occurring water dispersible clay such as bentonite can be reacted with long chain quaternary ammonium compounds to produce hydrophobia clay complexes. These organically modified clay complexes have been found to have utility in a wide variety of applications, where it is desired to impart greater viscosity, gellation and antisettling properties etc. to an organic liquid. The modified clay complexes have specific property for their uses in (i) lubricant industry, as versatile gellant. to thicken oil to semi-solid or solid consistency, (ii) paints, lacquers and stains, as an excellent suspending agent, that inhibits separation of pigments and fillers, (iii) printing ink , as a valuable viscosity controller to prevent throw-off at high speed printing operation, (iv) waxes, to provide high tensile strength, (v) adhesivcs. ( like asphalt and rubber ) to impart bond strength and improve moisture resistance, (vi) drilling fluids like oil based muds, it is used for drill-stem lubrication, and for corrosion protection, (vii) fiber glass resin as thixotrop, to prevent the separation and sagging of fiberglass during curing and enable easy spraying of the liquid resin. The organophilic clays are the reaction products of highly purified bentonite clay and a long chain quaternary ammonium compound. Under favourable conditions, the cation of the organic compound undergoes ion-exchange reaction with clay which contain a negatively charged layer-lattice and exchangeable inorganic cations, to form organophilic clays which possess the property of being compatible with many oyanic liquids. Reference may be made to E. A .Hauser, U.S. Patent No.2.531.427(1950) and J.W.Jordan, U.S. Patent No.2,966,506(1960) both included herein by reference and the book "The Chemistry of Clay - Organic Reactions" 1974 by B.K..G. Iheng (John Wiley & Sons), Chapter 5, Interaction with positively charged organic species. PP 211-238. Howard Goodman in U.S. Patent No.4.631.091 (1985). has described the use of inorganic salt viz. Al2(SO.Oj or AlCb to flocculate the purified bentonite clay prior to reaction with higher alkyl containing quaternary ammonium compounds in order to obtain organophilic clays that are readily dispersible in organic liquids. The drawback associated with this invention is that, after the flocculation step the removal of traces of flocculating agent by repeated washing is time consuming and labourous. liven at ppm level the clay gets flocculated and does not remain in suspension for long period. T.R. Jones et al. in an European Patent No.220. 346 (1987) has disclosed the use of higher alkyl containing quaternary ammonium compound in organic solvent and homogenisation of clay slurry under high energy pug milling in order to manufacture organoclay having enhanced gelling properties. The drawback of this method is that the use of organic solvent to prepare a clear solution of quaternary ammonium compound and latter the recovery of this organic solvent from end liquor makes the process complicated and uneconomical. M.I.Knudson Jr .ct al. in U.S.Pat. No .4.664.842 (1987) recommends that the clay slurry be exposed to high speed fluid sheer i.e. homogenisation with 5000 psig pressure, to reduce the particle size of clay before its interaction with dimeths Idihydrogenated tallow ammonium salt in organic solvent. The patent discloses that the reaction was carried out at 60° C with stirring for about 30 minutes. The drawback of this invention is that homogenisation at high pressure involve large energy. Thereby one unit operation is also increased. Moreover, the basic ion-exchange reaction is carried out at 60 ° C and maintained for 30 minutes, This will also increase the energy (power) consumption in the process. It is disclosed by N.T.Doidge et al. in U.S. Pat. No.4. 743, 305 (1988) that organoclay readily dispersible in organic media is prepared by subjecting the crude bentonite slurry to sedimentation , sieving and homogenisation at 5000 psig pressure to remove non-clay components before its interaction with quaternary ammonium compounds. This patent also c discloses the interaction of dimethyldihydrogenated tallow ammonium chloride in Me2CHOH with purified bentonite clay while maintaining the temperature around 60°C for about 30 minutes. This mixture was aged for 20 minutes at high speed. The drawback associated with this invention is that purification steps involves many unit operation steps. This will also simultenously increase the overall time of reaction of one particular batch. Besides, the reaction was carried out at higher temperature. Therefore energy (power) consumption will be increased. It is well documented in a book by C.J. Boner ."Manufacture and Application of Lubricating Grease" (1954) (Reinhold Publishing Corp.) Clay Base Thickners, PP 724-748 which depicts the effect of variables on the gelation of lubricating oil by organoclays to form grease. Another article "The gelation of Hydrocarbons by Montmorillonite Organic Complexes" by W.T. Granquist and J.L. McAttee Jr., J. Colloid Science. 18. 409-420 (1963) discloses the use of organophilie clay gellants and polar organic dispersants as viscosifiers in organic systems, The main objective of the present invention is to provide a process for the preparation of improved organophilic clay useful as gallants for making viscous organic systems, which obviates the drawbacks as detailed above. Another object of the present invention is to provide organophilic clay with high degree of hydrophobicity and that is compatible with organic liquids. Still another object of the present invention is to provide organically modified clay complexes with large basal spacing, high gel volume, low surface area, controlled moisture and nitrogen content which are the prerequisites for higher viscosity, improved gellation, better antisettling property in organic liquids and mineral oils. Another and more particular object of the present invention is to provide organically modified clay complexes capable of thickening a wide variety of mineral oils to produce a gelled system that displays a high degree of stability when subjected to'mechanical working. Yet another object of the present invention is to provide an economical, simple and practical method for producing the product without being subjected to the disadvantages and complexities involved in other known techniques, Accordingly the present invention provides a process for the preparation of organophilic clay useful as gellants for making viscous organic systems which comprises i) dispersing 2 to 3 weight percent of raw smectite clay selected from bentonite in de mineralized water under stirring by known method, to obtain a slurry; ii) purifying the said dispersed clay slurry by known methods to obtain cation exchange capacity of 60 miliequivalent per 100 g clay and a water swelling capacity of 20 cc: iii) converting the purified bentonite clay slurry to homo ionic form by reacting with concentrated alkali metal inorganic salt solution. Such as herein described hydrochloric acid or by passing the clay slurry through the cationic form of ion exchange resin; iv) preparing a solution of quaternary ammonium salt in dematerialized water at 70°equivalent to the cation exchange capacity of the purified clay: v) adding the quaternary ammonium salt solution as obtained in step (iv) to the homoionic clay slurry as obtained in step (iii) at room temperature under constant agitation, allowing the reaction mixture to age under stirring to obtained flocculated clay, separating the flocculated clay by known methods, to obtain wet cake of organophilic clay; vi) drying the wet cake in an air circulated oven, while maintaining the temperature at 65 °Celsius, until the free moisture is 3 percent; (vii)pulverizing the dry granules in a steel hammer mill to obtain a organophilic clay. In the process of the present invention the reaction product of a bentonite clay having cation exchange capacity of at least 60 mill equivalent per 100 grams of the said clay and a dimethyl benzyl alkyl ammonium compound, wherein the said alkyl radical independently contains from 12 to 22 carbon atoms and wherein the amount of said ammonium compound is within the range from 90 to less than 110 milliequivalent per 100 grams of clay, based upon 100 percent active clay, using 6 to 10 percent by weight of said organophilic clay to enhance dispersibility and the gel formation of mineral oil with addition of polar activator in the range of 0.6 to 1.0 percent by weight to obtain grease. The polar activator is added to increase the gelling efficiency of organophilic clay. In an embodiment of the present invention the smectite clays such as bentonite used can be either in lump or powder form and the purified clay must have a basal spacing in the range 12-16 A* cation exchange capacity of at least 60 mill equivalent per 100 grams of clay and water swelling capacity more than 20cc. In another embodiment of the present invention the quaternary ammonium compounds used contains at least 12 carbon atoms in alkyl group preferably with 20 to 30% of alkyl group containing 16 carbon atoms and 60 to 75 % of alkyl group containing 18 carbon atoms. In yet another embodiment-of the present invention the quaternary ammonium compound solution is added to the clay slurry over a period of 30 to 70 minutes. In still another embodiment of the present invention the reaction mixture is aged for at least 45 minutes. In yet another embodiment of the present invention the quaternary ammonium compounds used are such as (i) dimethyl benzyl stearyl ammonium chloride , (ii) dimethyl benzyl cetyl ammonium chloride, (iii) dimethyl dioctadecyl ammonium chloride and (iv) dimethyl dihydrogenated tallow ammonium chloride. In still another embodiment of the present invention the quaternary ammonium salt solution used are in concentration range of 0.01 M to 0.1M. The clays which are useful in the practice of this invention are those that belong to a class known as smectites and are characterised by a three layer, platelet structure. In nature, bentonile clay exists as stacks of platelets, similar to the pages in a book. Bentonite and hcctorite (Smectite group) are characterised by a negatively charged layer lattice structure, which arises from the replacement of some higher valency positive lattice atoms with the lower valency atoms of similar si/.e (i.e. isomorphous substitution) eg. magnesium replaces some of the aluminium atoms in bentonites and lithium replaces some magnesium atoms in hectorite. The negative charges developed are reflected on both faces of the clay platelets where they arc counter balanced, in nature, by inorganic cations such as Na4,Mg'~ and Ca\ These cations are not a part of the lattice structure and are relatively easy to replace. Therefore, these clays possess a substantial base exchange capacity. Besides this, another important property of bentonite (smectite) is the swelling capacity in water. A particular desirable type of clay, from which organically modified clay complexes can be prepared is the naturally occuring swelling type bentonite and the like clays and hectorite a swelling magnesium lithium silicate clay. These clays exhibit swelling capacity in water in the range of 20 to 30 times its own volume and has base exchange capacity in the range of 60-100 milliequivalents per 100 grams of clay as determined by ammonium acetate method. A typical, naturally occuring bentonite has about 60% of its base exchange capacity satisfied by sodium ions with the remainder of its exchangeable ions being calcium and magnesium, out of them calcium is in major proportion. Naturally occuring bentonite clays having sodium ion in major proportion are called sodium bentonite clay. In addition to the bentonite clays mentioned above, we have found that clays having different origin and chemical composition are also useful in the preparation of organoclay provided that, it possesses the inherent characteristics viz. (i) swelling in water (ii) high base exchange capacity and (iii) intercalation property. These clays are characterised by an unbalanced crystal lattice and have negative charges which are neutralized as available in nature by inorganic metal ions. These cations to varying degree are capable of being replaced by other inorganic or organic cations. The quaternary ammonium compounds used in the practice of this invention are quaternary ammonium salts containing at least one long chain alkyl group having from 12 to 22 carbon atoms, preferably 16 to 18 carbon atoms and more preferably 20% to 30% of the alkyl groups containing 16 carbon atoms and 60% to 75% containing 18 carbon atoms. The long chain alkyl group provide hydtophobic characteristic. In addition to long chain carbon molecule the other groups that are attached to the cation centers are divided into two classes viz. (i) Filler groups and (ii) Active groups The filler groups are small chain alkyl radicals that complete the tetrahedron around the nitrogen. It does not offer any beneficial effects to the organoclay performance. The typical examples of filler groups are hydrogen and short chain alkyl groups viz methyl, ethyl, butyl. The active groups which is a small part of the total cation, have a beneficial contribution to the organoclay performance. Typical examples of active groups are benzyl and 2 hydroxy ethyl. The cations containing these groups will not significantly increase the basal spacing between the clay platelets but provide both greater solvent polarity range and improved ease of dispersion to the organoclay. Anions such as Cl , Br , acetate, hydroxide, nitrate, nitrite, etc may be present in the quaternary ammonium compound to balance the charge of cation. Generally salt having Cl , Br or mixture of them as anion is selected These quaternary ammonium salts can be represented by the formula where RI and RT are methyl groups. RS is the aryl group and R4 is the long chain alkyl group containing a mixture of 12 to 22 carbon atoms wherein the major portion is of C\|6 -C\|g carbon atoms. This alkyl chain has 20% to 30% have 16 carbon atoms and 60% to 75% have 18 carbon atoms, based on 100% and where X " is preferably selected from the group consisting of Cl Br . NO.i .OH . (MhO: and mixtures thereof. In accordance with the present invention it has been found that organically modified clay complexes can be prepared by introducing a dilute solution of quaternary ammonium salt (such as dimethyl alkyl aryl ammonium chloride) to a dilute aqueous dispersion of clay (montmorillonite and the like) that has been, prior to reaction with quaternary ammonium salt converted to homoionic form. The reaction can be represented by the general formula In the present invention, the starting material or reactants employed include bentonite clays and quaternary ammonium compounds (cationic surfactant). As used herein, the bentonite clay is in the highly purified state with major portion being montmorillonite clay. It is particularly advantageous because montmorillonite in pure form possesses high swelling power and base exchange capacity. The montmorillonite clay is effective/suitable in high cation exchange capacity, in which the exchange capacity must be in the range of 60 to 100 millicquivalents per 100 grams of clay. The swelling capacity in water must be about 20 times than the original volume of raw clay. The commercially available quaternary ammonium compound is used, which is completely soluble in water. It contained atleast one long chain alkyl group containing atleast 12 carbon atoms. The other groups attached to the cation may be (i) "Filler" group which serves to complete the tetrahedron around the nitrogen and (ii) The "Active" group (Aryl group) which contributes to organoclay performance by providing greater solvent polarity and improved ease of dispersion. The cations must have sufficient hydrophobic character to impart organophilic character to the modified clay reaction product. The preparation of organically modified clay complexes such as is contemplated by this invention is accomplished by first dispersing a naturally occuring clay lumps/powder, in demineralized water to produce a dilute slurry. This dilute clay slurry is then subjected to separation / upgradation process which causes the removal of non-clay contaminants from the montmorillonite clay particles. This separation can be readily accomplished by permitting the contaminants to settle out of a dilute aqueous dispersion of the clay or they can be removed by hydrocyclone or centrifugation techniques. This step may be conveniently carried out either before or after converting the clay into a desirable homoionic form. Many of the non-swelling bentonitc clays exhibit in their natural state the base exchange capacity satisfied w ith Ca+" and Mg*~ which are comparatively difficult for organic cations to replace. It has been found that a much improved organically modified clay complexes can be prepared by subjecting the clay to an ion-exchange treatment to replace Ca+2 and Mg+" ions by sodium or any monovalent ion. prior to reacting it with quaternary ammonium compound of the type described. In commercial practice, one of the most widely used methods for preparing a homoionic clay is by passing a dilute clay slum.' through an ion-exchange resin column using a fixed bed technique. Other method in which clay slurry is mixed with resin under agitation can also be used to prepare homoionic clay. In the practice of this invention, another method of preparing homoionic clay which can be employed is by repeatedly leaching the clay slurry with a solution of water soluble metal salt or acid and subsequently washing the clay free of excess salt. In general, the ion-exchange reaction between the charge balancing cations of the clay and cations of quaternary ammonium salts can be carried out over a wide range of temperature. According to this invention, the improved characteristics i.e. high degree of hydrophobicity ( high retention of organic cations on clay ) is obtained when the reaction as hitherto described is carried out at a temperature within the range of 35°C to 75°C or higher, although it was observed that there is no particular advantage in higher reaction temperature. It is understood that high degree of hydrophobicity depends significantly upon the selectivity of organic cation in the interlayer space of clay, in place of inorganic charge balancing cations. Such selectivity for organic cation is related to the easy availability of organic cations in solution which is temperature related. The interaction at controlled temperature leads to the production of modified clay complexes having higher hydrophobicity and required surface characteristics. In so far as the temperature of dispersed clay slum- is concerned, it is not critical and it may be delivered at room temperature or higher as per the objective of the invention. In accordance with the broad aspect of the present invention, the ion-exchange reaction having particular regard to the co-mingling of the total quantities of the two reactants, is subject to a variety of approaches. The total quantities of the reactants can be co-mingled very rapidly or very slowly, in both the cases the ion-exchange reaction will take place. In practising this invention, it is found desirable not to complete the addition of quaternary ammonium salt solution in a period of time shorter than 30 minutes. Moreover, it may be mentioned here that little or no advantage is gained by unduly prolonging the addition time. In no instance, it is found to be desirable to extend the addition time, beyond a period of about 70 minutes. A more suitable range for producing the organoclay with high hydrophobicity is from about 30 to 40 minutes, besides the aging time, before the flocculated clay is filtered. In this invention it is not found to be advantageous to disregard the rate of co-mingling of readmits, because the uniformity of the particulate mass composing the end product is rendered poor or economics is adversely affected. According to this invention, number of conditions are varied, as directed above to obtain modified organoclay with improved surface properties. One such important aspect of the present invention involves the clay concentration and molar concentration of quaternary ammonium salt solution. For those skilled in the art of manufacture of organoclay, it is understood that a dilute aqueous dispersion of clay must be present as a part of the reaction medium right from the inception of the reaction, otherwise the end product fails to acquire the physical / surface characteristics falling within the specified range. In practising this invention, the raw clay is dispersed in demincraliscd water at a concentration from about 1 to 5 percent by weight. The slurry optionally sedimented / hydrocycloned and / or centrifuged to remove non-clay impurities which constitute about 30 to 40 percent by weight of the starting clay composition. Thus, the purified clay slurry contains montmorillonite clay, within the range of about 0.5 to 4.0 percent, particularly and preferably in the range of about 1 to 3 per cent. At lower concentration, degree of hydrophobicity or in other words the retention of organic cations by the clay, is higher. At higher concentration, the organophilic clays are poor gellants. The quaternary ammonium salt solution is prepared containing organic cations within the range of about 0.01 M to 0.1M, preferably in the range of about 0.02 M to 0.07M. It is further found in this investigation that dilution of quaternary ammonium salt does not help in improving the surface properties of the end product. At the same time, increasing the concentration beyond a certain limit, no advantage is gained. In practising this invention the quaternary ammonium salt solution is prepared in the desired milliequivalent ratio, either dispersed or dissolved in demineralised water.The amount of quaternary ammonium salt added to the clay must be sufficient to impart to the organophilic clay the enhanced gellation characteristics desired. The milliequivalent ratio is the number of milliequivalent of the quaternary ammonium compound in organophilic clay per 100 grams of clay. The modified organoclay complexes of this invention have a milliequivalent ratio from 90 to 110. At lower milliequivalent ratio, the organophilic clays are ineffective gellants. even though they may be effective gellants in presence of a polar additive. At higher milliequivalent ratio the organophilic clay are poor gellants. However, the preferred milliequivalent ratio within the range from 90 to 110 will vary depending on the characteristics of the organic system to be gelled by the organophilic clay. Upon completion of the addition of the quaternary ammonium salt solution and given the sufficient aging time for the ion-exchange reaction to be completed, the flocculation of organically modified clay complexes takes place. The latter readily separated from the aqueous phase by filtration, but other means of separation, such as centrifuge / filter press can be used. It is preferable to wash the product with demineralised water to remove adhering water soluble salts and the like. The filter cake is then dried in an air-circulated oven. The amount of water remaining in the powder depends upon the time, temperature and other conditions of drying. The dried cake can be pulverised to produce a fine pulverulent product with the help of a hammer mill. A simple gel volume measurement method has been adopted to illustrate the compatibility (dispersion) of organophilic clay prepared in this invention. In this method, 2 grams of organophilic clay is slowly added to a toluene-methanol mixture (80 : 20 by volume) taken in a 100 ml graduated stoppered glass cylinder and thoroughly shaken to uniformly disperse the clay. The volume of gel in millilitres is recorded after 24 hours. The milliequivalents of the organic compound retained in the organophilic clay is calculated from the ignition loss at 800°C of (i) clay-organic complex (ii) hydrophilic upgraded clay and (iii) molecular weight of quaternary ammonium cation. The free moisture is measured by keeping the sample in oven at 105°C for 2 hours The product so obtained has the following properties :(Table Removed) In the present invention, bentonite clay having (i) basal spacing in the range of 12-16A0 (ii) cation exchange capacity in the range of 60 to 110 milliequivalents per 100 grams of dry clay, (iii) swelling capacity in water more than 20 cc.. was used The bentonite with above properties should have Silica (as SiOi ) 45-55 %: Alumina (as AN O.i ) 20-25 %; Iron oxide (as Fe: O.; ) 7-12 %: Magnesium oxide ( as MgO) 2-4 %; Sodium oxide ( as NaaO) 1-3 % and Calcium oxide (as CaO) 1-4 %. The impurities (non-clay fractions) were removed by sedimentation /centrifugation technique. Different homoionic forms viz. Na and H were prepared either by using ion-exchange resin or concentrated inorganic salt solution. The typical quaternary ammonium compounds which have been used in the practice of this invention includes (i) Dimethyl benzyl stearyl ammonium chloride (ii) Dimethyl benzyl cetyl ammonium chloride, (iii) Dimethyl dioctadccyl ammonium chloride, (iv) Dimethyl dihydrogenated tallow ammonium chloride. Any of the above compounds can be used with an ion-exchange treated clay to produce an organically modified clay complex. The molecular weight of these organic compounds ranged from 390 to 590. Using the above organophilic clay the grease may be prepared from lubricating oil having the following properties. (Table Removed) Now in accordance with the present invention it has been found that no special equipment is required in the process herein described. The reaction vessel should be equipped with an adequate agitator which produces a strong back flow of slurry and avoids zone of high concentrations of the reactants. The storage vessels for (i) purified clay slurry and (ii) quaternary ammonium salt solution, are connected to the reaction vessel through lines fitted with flow control means. The reaction vessel is equipped with an outlet line fitted at the bottom leading to a filter which may be of the plate and frame type or a centrifuge. The filter cake is washed with water until the test for chloride is negative with silver nitrate. The filtered and washed mass is dried in air circulated tray dryers. This method of preparation generates a very dilute effluent which contains soluble salts and very less quantity of unreacted organic cation. The effluent is acidic in nature and can be neutralised by a small amount of alkali., before its disposal. In the present invention, an improved organophilic clay gellants are prepared from a purified clay slurry and a clear solution of quaternary ammonium sail. The process imbibes a simple ion-exchange reaction between the interlayer inorganic cations of clay and the organic cations of quaternary ammonium salt, under ambient and experimental conditions. The organo-clay so prepared possess a high degree of hydrophobicity. The byproduct such as sodium chloride is removed by washing. In this method, the simple inventive steps adopted are (i) dispersing the bentonite clay demineralised water without the use of dispersing agents; (ii) the purified clay slurry so obtained is used as such and does not need homogenisation at high pressure ; (iii) the homo-ionic clay is prepared by addition of dilute mineral acid ; (iv) the quaternary ammonium compounds are readily soluble in hot water and (v) the basic ion-exchange reaction is carried out at ambient temperature. The clay used in this process, have sites in the interlayer space, where the exchange of ions takes place. This space can be expanded and organic cation of large molecular size can be accomodated. The organic cations orient in mono-, di-. or pseudo layer depending on the experimental conditions. The quaternary ammonium compound used in this process have an active group with a hydrophobic character which is found to be responsible for the conversion of hydrophilic character of clay to hydrophobic character. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. EXAMPLE 1 An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry were removed by sedimentation and / or hydrocyclonc techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grains of clay. The slurry, which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid. This H-form of the clay slurry was kept at room temperature and a solution of dimethyl benzyl stearyl ammonium chloride prepared in hot (70°C)-demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product. EXAMPLE 2 An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as detennined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and /or hydrocyclone techniques. After purification, the base exchange capacity was found to be about °o milliequivalent per 100 grams of clay. The slurry which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-form of the clay slurry was kept at room temperature and a solution of dimethyl benzyl cetyl ammonium chloride prepared in hot (70°C) demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product. KXAMI'LK 3 An aqueous clay slurry .of Akli bentonite collected from Barmer district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 millicquivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and / or hydrocyclone techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grams of clay. The slurry which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-form of the clay slurry was kept at room temperature and a solution of dimethyl dioctadecyl ammonium chloride prepared in hot (70°C) dimineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product. EXAMPLE 4 An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and / or hydroc) clone techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grams of clay. The slurry which contained about 1 weight % (weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-lbrm of the clay slurry was kept at room temperature and a solution of dimethyl dihydrogenated tallow ammonium chloride prepared in hot (70°C) demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulveri/ed to obtained a finely pondered product. The preliminary properties of these organophilic clays prepared so far. are shown in Table 1 The results shows the improved compatibility (dispersion) of organoclay with organic solvents and better retention of quaternary ammonium compound on clay surfaces. The data in Table 1 indicates the increase in the ease of dispersion of organophilic clay prepared from dimethyl benzyl stcaryl ammonium chloride and montmorillonite clay when the amount of this quaternary ammonium chloride was in the range of 90 to 110 milliequivalents per 100 grams of clay. The data also depict better retention characteristics of organic cation on clay surface as compared to organophilic clays prepared from somewhat similar but different quaternary ammonium compounds. TABLE - 1 (Table Removed) ME=milliequivalent. EXAMPLE 5 An aqueous clay slurry of Hathi-Ki-Dhani bentonite powder collected from Jodhpur district of Rajasthan, India was prepared in demineralised water containing 1.7 % raw clay by weight. This raw clay had a base exchange capacity of 60 milliequivalent per 100 grams of clay and a swelling capacity of 32 cc in demineralised water. The clay was purified by subjecting the clay slurry to sedimentation and siphoning the clay fractions. After the purification step, the clay had a base exchange capacity of 93 milliequivalent per 100 grams of clay and the swelling capacity was 36 cc. The clay slurry which contained 1 weight % (weight by volume) of clay was brought to hydrogen form by adding dilute hydrochloric acid. This H- form of clay slurry was kept at room temperature and a solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) dimineralised water was added in 45 minutes to the agitated clay suspension. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to and more than the base exchange capacity of clay. The reaction mixture was agitated continuously for another 60 minutes. The well-flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demincralised water, dried at 65 ° C in air circulated oven and pulverized to obtained a finely powdered product. The properties of this organophilic clay are shown in Table 2. TABLE 2 (Table Removed) ME = milliequivalent EXAMPLE 6 The Akli bentonitc lumps collected from Banner district of Rujasthan , India, was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35° C and under continues stirring an aqueous solution of dimethyl benzyl stearyl ammonium chloride, separately prepared in hot (70°C) dcmineraliscd water was added in 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The flocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65° C . The granules were pulverized to obtain fine powder. The organophilic clay prepared above was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. EXAMPLE 7 The Akli bentonite lumps collected from Banner district of Rajasthan .India, was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35" C and under continuous stirring an aqueous solution of dimethyl benzyl cetyl ammonium chloride separately prepared in hot (7()°C) demineralised water. wras added in 45 minutes. The amount of dimethyl benzyl cetyl ammonium chloride added was just equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The ilocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65" C . The granules were pulverized to obtain fine powder. The organophilic clay prepared above was used as gellants at a concentration of 9% by weight inmineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpin. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an AS'I'M grease worker assembly EXAMPLE 8 The Akli bentonite lumps collected from Banner district of Rajasthan India .was dispersed under strong agitation for 2 hours in demineralized water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grains of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35° C and under continuous stirring an aqueous solution of dimethyl dioctdecyl ammonium chloride separately prepared in hot (70°C) demineralised water was added in 45 minutes. The amount of dimethyl dioctadecyl ammonium chloride added was just equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The Ilocculated organoclay complex was filtered by known methods, washed with demineralised \\ater and dried at 65'V . The granules were pulveri/ed to obtain fine powder. The organophilic clay prepared above was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. EXAMPLE 9 The Akli bentonite lumps collected from Banner district of Rajasthan. India .was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic fonn by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35" C and under continuos .stirring an aqueous solution of dimethyl dihydrogenated tallow ammonium chloride separately prepared in hot (70°C) demineralised water was added in 45 minutes. The amount of dimethyldihydrogenated tallow ammonium chloride added was just equivalent to the base exchange capacity of clay.The reaction mixture was agitated lor another 45 minutes. The flocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65 ° C . The granules were pulverized to obtain fine powder. The organophilic clay prepared above was used as gellants at a concentration of 9% by weight inmineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, alter setting for 24 hrs were obtained for unworkecl and after working the grease for 50 strokes in an ASTM grease worker assembly. The results are shown in Table 3. . TABLE-3 (Table Removed) ME = milliequivalents EXAMPLE 10 The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand lor 24 hours (sedimentation) so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay.This clay shiny was converted to hydrogen form by adding dilute hydrochloric acid. This clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtain fine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.2% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. EXAMPLE 11 The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand for 24 hours (sedimentation) so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had an cation exchange capacity of 95 milliequivalcnt per 100 grams clay. This clay slurry was converted to hydrogen form by adding dilute hydrochloric acid. 1 his clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was. 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 °C. The granules were pulveri/cd to obtainfinc powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.4% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was thru added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. EXAMPLE 12 The Akli bcntonitc lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slum' was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay slurry was converted to hydrogen form by adding dilute hydrochloric acid. This clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl ben/yl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulveri/ed to obtainfine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.6% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. EXAMPLE 13 The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dcmineraliscd water for 2 hours at a concentration of 17 g clay per liter. Then the clay slum' was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slum' (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay slum- was converted to hydrogen form by adding dilute hydrochloric acid. This clay slum1 at room temperature (35"C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtainfine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrcr rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly EXAMPLE 14 The Akli bentonite lumps, collected from Banner tlistrict of Rajaslhan. India was dispersed under strong agitation in demineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by \vt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay shiny was converted to hydrogen form by adding dilute hydrochloric acid. This clay slum- at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtainfine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 1.0 % propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogcniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. The results are shown below.(Table Removed) The main advantages of the present invention are : 1. The bentonite clay, either in powder or lumps, can be readily dispersed in demineralised water under strong simple agitation. It does not require any dispersing agent. 2. The clay slurry after purification by known techniques is not required to be subjected to homogenization under high pressure. 3. The homo-ionic form of the clay slurry can be easily prepared by simple addition of mineral acid viz. hydrochloric acid. 4. The quaternary ammonium compounds are used in the present invention are readily soluble in hot demineralised water. 5. The basic ion exchange reaction is carried out at ambient temperature (35° C). We Claim: 1. A process for the preparation of organophilic clay useful as gellants for making viscous organic systems which comprises i) dispersing 2 to 3 weight percent of raw smectite clay selected from - fcfort t fanfr o twvdtt fyfftf f- hodfff rtbe£f f bentonite in dejnineralized water under stirring by known method, to obtain a slurry, ii) purifying the said dispersed clay slurry by known methods to obtain cation exchange capacity of 60 miliequivalent per 100 g clay and a water swelling capacity of 20 cc, iii) converting the purified bentonite clay slurry to homoionic form by reacting with concentrated alkali metal inorganic salt solution such as herein described or hydrochloric acid or by passing the clay slurry through the cationic form of ion exchange resin, iv) preparing a solution of quaternary ammonium salt in de mineralized water at 70°equivalent to the cation exchange capacity of the purified clay, v) adding the quaternary ammonium salt solution as obtained in step (iv) to the homo ionic clay slurry as obtained in step (iii) at room temperature under constant agitation, allowing the reaction mixture to age under stirring to obtained flocculated clay, separating the flocculated clay by known methods, to obtain wet cake of organophilic clay, vi)drying the wet cake in an air circulated oven, while maintaining the temperature at 65 °Celsius, until the free moisture is 3 percent; (vii)pulverizing the dry granules in a steel hammer mill to obtain a organo philic clay. 2. A process, as claimed in/claim 1, wherein the bejrfonite clay used are^in either lump or powder form arid the purified clay/has a basal spacing o£-12-16 Axtfation exchange capacity of 60 mill equivalent per/10-O) grams oi'clay andjsvater swelling capacityn20cc. A process, as claimed in claims 1 & 2, wherein the quaternary ammonium compounds used contains at least 12 carbon atoms in alkyl group with preferably 20 to 30% of alky group containing 16 carbon atoms and 60 to 75% of alkyl group containing 18 carbon atoms. A process as claimed, in claims 1 to 3 wherein the dimethyl benzyl stearyl ammonium compound solution is added to the clay slurry over a period of 30 to 70 minutes. A process as claimed, in claims 1 to 4 wherein the reaction mixture is agedopo) a I period of at least 45 minutes. . A process as claimed, in claims 1 to 5 wherein the quaternary ammonium compounds used are, (i) dimethyl benzyl stearyl ammonium chloride (ii) dimethyl benzyl cetyl ammonium chloride (iii) dimethyl dioctaecyl ammonium chloride (iv) dimethyl dehydrogenated tallow ammonium chloride. 7. A process asdaimed in claims 1 to 6, wherein the concentration of quaternary ammopktmchloride solution are in the range ofOfto 0.1 molar. X? A process for the preparation of (Hauweve? organophilic clay useful as gellants for making viscous organic systems substantially as herein described with references to the examples. .

Full Text

The present invention relates to a process for the preparation of improved organophilic clay useful as gellants for making viscous organic systems.
In the field of chemical technology this invention relates to the modified clay complexes and to a method of preparing them. More particular!}' this invention relates to the ion-exchange process for the preparation of hydrophobia clay complexes which are compatible with organic liquids / mineral oils in contrast to an unmodified hydrophilic clay that is easily dispersible in water.
The preparation of organpclay complexes that are compatible with organic liquids has been known for some time. A naturally occurring water dispersible clay such as bentonite can be reacted with long chain quaternary ammonium compounds to produce hydrophobia clay complexes. These organically modified clay complexes have been found to have utility in a wide variety of applications, where it is desired to impart greater viscosity, gellation and antisettling properties etc. to an organic liquid. The modified clay complexes have specific property for their uses in (i) lubricant industry, as versatile gellant. to thicken oil to semi-solid or solid consistency, (ii) paints, lacquers and stains, as an excellent suspending agent, that inhibits separation of pigments and fillers, (iii) printing ink , as a valuable viscosity controller to prevent throw-off at high speed printing operation, (iv) waxes, to provide high tensile strength, (v) adhesivcs. ( like asphalt and rubber ) to impart bond strength and improve moisture resistance, (vi) drilling fluids like oil based muds, it is used for drill-stem lubrication, and for corrosion protection, (vii) fiber glass resin as thixotrop, to prevent the separation and sagging of fiberglass during curing and enable easy spraying of the liquid resin.
The organophilic clays are the reaction products of highly purified bentonite clay and a long chain quaternary ammonium compound. Under favourable conditions, the cation of the

organic compound undergoes ion-exchange reaction with clay which contain a negatively charged layer-lattice and exchangeable inorganic cations, to form organophilic clays which possess the property of being compatible with many oyanic liquids. Reference may be made to E. A .Hauser, U.S. Patent No.2.531.427(1950) and J.W.Jordan, U.S. Patent No.2,966,506(1960) both included herein by reference and the book "The Chemistry of Clay - Organic Reactions" 1974 by B.K..G. Iheng (John Wiley & Sons), Chapter 5, Interaction with positively charged organic species. PP 211-238.
Howard Goodman in U.S. Patent No.4.631.091 (1985). has described the use of inorganic salt viz. Al2(SO.Oj or AlCb to flocculate the purified bentonite clay prior to reaction with higher alkyl containing quaternary ammonium compounds in order to obtain organophilic clays that are readily dispersible in organic liquids. The drawback associated with this invention is that, after the flocculation step the removal of traces of flocculating agent by repeated washing is time consuming and labourous. liven at ppm level the clay gets flocculated and does not remain in suspension for long period.
T.R. Jones et al. in an European Patent No.220. 346 (1987) has disclosed the use of higher alkyl containing quaternary ammonium compound in organic solvent and homogenisation of clay slurry under high energy pug milling in order to manufacture organoclay having enhanced gelling properties. The drawback of this method is that the use of organic solvent to prepare a clear solution of quaternary ammonium compound and latter the recovery of this organic solvent from end liquor makes the process complicated and uneconomical. M.I.Knudson Jr .ct al. in U.S.Pat. No .4.664.842 (1987) recommends that the clay slurry be exposed to high speed fluid sheer i.e. homogenisation with 5000 psig pressure, to reduce the particle size of clay before its interaction with dimeths Idihydrogenated tallow ammonium salt in organic solvent. The patent discloses that the reaction was carried out at 60° C with

stirring for about 30 minutes. The drawback of this invention is that homogenisation at high pressure involve large energy. Thereby one unit operation is also increased. Moreover, the basic ion-exchange reaction is carried out at 60 ° C and maintained for 30 minutes, This will also increase the energy (power) consumption in the process.
It is disclosed by N.T.Doidge et al. in U.S. Pat. No.4. 743, 305 (1988) that organoclay readily dispersible in organic media is prepared by subjecting the crude bentonite slurry to sedimentation , sieving and homogenisation at 5000 psig pressure to remove non-clay components before its interaction with quaternary ammonium compounds. This patent also c discloses the interaction of dimethyldihydrogenated tallow ammonium chloride in Me2CHOH with purified bentonite clay while maintaining the temperature around 60°C for about 30 minutes. This mixture was aged for 20 minutes at high speed. The drawback associated with this invention is that purification steps involves many unit operation steps. This will also simultenously increase the overall time of reaction of one particular batch. Besides, the reaction was carried out at higher temperature. Therefore energy (power) consumption will be increased.
It is well documented in a book by C.J. Boner ."Manufacture and Application of Lubricating Grease" (1954) (Reinhold Publishing Corp.) Clay Base Thickners, PP 724-748 which depicts the effect of variables on the gelation of lubricating oil by organoclays to form grease. Another article "The gelation of Hydrocarbons by Montmorillonite Organic Complexes" by W.T. Granquist and J.L. McAttee Jr., J. Colloid Science. 18. 409-420 (1963) discloses the use of organophilie clay gellants and polar organic dispersants as viscosifiers in organic systems,

The main objective of the present invention is to provide a process for the preparation of improved organophilic clay useful as gallants for making viscous organic systems, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide organophilic clay with high degree of hydrophobicity and that is compatible with organic liquids.
Still another object of the present invention is to provide organically modified clay complexes with large basal spacing, high gel volume, low surface area, controlled moisture and nitrogen content which are the prerequisites for higher viscosity, improved gellation, better antisettling property in organic liquids and mineral oils.
Another and more particular object of the present invention is to provide organically modified clay complexes capable of thickening a wide variety of mineral oils to produce a gelled system that displays a high degree of stability when subjected to'mechanical working.
Yet another object of the present invention is to provide an economical, simple and practical method for producing the product without being subjected to the disadvantages and complexities involved in other known techniques,
Accordingly the present invention provides a process for the preparation of organophilic clay useful as gellants for making viscous organic systems which comprises
i) dispersing 2 to 3 weight percent of raw smectite clay selected from
bentonite in de mineralized water under stirring by known method, to
obtain a slurry; ii) purifying the said dispersed clay slurry by known methods to obtain
cation exchange capacity of 60 miliequivalent per 100 g clay and a water
swelling capacity of 20 cc: iii) converting the purified bentonite clay slurry to homo ionic form by
reacting with concentrated alkali metal inorganic salt solution. Such as
herein described hydrochloric acid or by passing the clay slurry through
the cationic form of ion exchange resin;

iv) preparing a solution of quaternary ammonium salt in dematerialized water at 70°equivalent to the cation exchange capacity of the purified clay:
v) adding the quaternary ammonium salt solution as obtained in step (iv) to the homoionic clay slurry as obtained in step (iii) at room temperature under constant agitation, allowing the reaction mixture to age under stirring to obtained flocculated clay, separating the flocculated clay by known methods, to obtain wet cake of organophilic clay;
vi) drying the wet cake in an air circulated oven, while maintaining the temperature at 65 °Celsius, until the free moisture is 3 percent; (vii)pulverizing the dry granules in a steel hammer mill to obtain a organophilic clay.
In the process of the present invention the reaction product of a bentonite clay having cation exchange capacity of at least 60 mill equivalent per 100 grams of the said clay and a dimethyl benzyl alkyl ammonium compound, wherein the said alkyl radical independently contains from 12 to 22 carbon atoms and wherein the amount of said ammonium compound is within the range from 90 to less than 110 milliequivalent per 100 grams of clay, based upon 100 percent active clay, using 6 to 10 percent by weight of said organophilic clay to enhance dispersibility and the gel formation of mineral oil with addition of polar activator in the range of 0.6 to 1.0 percent by weight to obtain grease. The polar activator is added to increase the gelling efficiency of organophilic clay.
In an embodiment of the present invention the smectite clays such as bentonite used can be either in lump or powder form and the purified clay must have a basal spacing in the range 12-16 A* cation exchange capacity of at least 60 mill equivalent per 100 grams of clay and water swelling capacity more than 20cc.
In another embodiment of the present invention the quaternary ammonium compounds used contains at least 12 carbon atoms in alkyl group preferably with 20 to 30% of alkyl group containing 16 carbon atoms and 60 to 75 % of alkyl group containing 18 carbon atoms.

In yet another embodiment-of the present invention the quaternary ammonium compound solution is added to the clay slurry over a period of 30 to 70 minutes.
In still another embodiment of the present invention the reaction mixture is aged for at least 45 minutes.
In yet another embodiment of the present invention the quaternary ammonium compounds used are such as (i) dimethyl benzyl stearyl ammonium chloride , (ii) dimethyl benzyl cetyl ammonium chloride, (iii) dimethyl dioctadecyl ammonium chloride and (iv) dimethyl dihydrogenated tallow ammonium chloride.
In still another embodiment of the present invention the quaternary ammonium salt solution used are in concentration range of 0.01 M to 0.1M.
The clays which are useful in the practice of this invention are those that belong to a class known as smectites and are characterised by a three layer, platelet structure. In nature, bentonile clay exists as stacks of platelets, similar to the pages in a book. Bentonite and hcctorite (Smectite group) are characterised by a negatively charged layer lattice structure, which arises from the replacement of some higher valency positive lattice atoms with the lower valency atoms of similar si/.e (i.e. isomorphous substitution) eg. magnesium replaces some of the aluminium atoms in bentonites and lithium replaces some magnesium atoms in hectorite. The negative charges developed are reflected on both faces of the clay platelets where they arc counter balanced, in nature, by inorganic cations such as Na4,Mg'~ and Ca\ These cations are not a part of the lattice structure and are relatively easy to replace. Therefore, these clays possess a substantial base exchange capacity. Besides this, another important property of bentonite (smectite) is the swelling capacity in water.

A particular desirable type of clay, from which organically modified clay complexes can be prepared is the naturally occuring swelling type bentonite and the like clays and hectorite a swelling magnesium lithium silicate clay. These clays exhibit swelling capacity in water in the range of 20 to 30 times its own volume and has base exchange capacity in the range of 60-100 milliequivalents per 100 grams of clay as determined by ammonium acetate method. A typical, naturally occuring bentonite has about 60% of its base exchange capacity satisfied by sodium ions with the remainder of its exchangeable ions being calcium and magnesium, out of them calcium is in major proportion. Naturally occuring bentonite clays having sodium ion in major proportion are called sodium bentonite clay. In addition to the bentonite clays mentioned above, we have found that clays having different origin and chemical composition are also useful in the preparation of organoclay provided that, it possesses the inherent characteristics viz. (i) swelling in water (ii) high base exchange capacity and (iii) intercalation property. These clays are characterised by an unbalanced crystal lattice and have negative charges which are neutralized as available in nature by inorganic metal ions. These cations to varying degree are capable of being replaced by other inorganic or organic cations.
The quaternary ammonium compounds used in the practice of this invention are quaternary ammonium salts containing at least one long chain alkyl group having from 12 to 22 carbon atoms, preferably 16 to 18 carbon atoms and more preferably 20% to 30% of the alkyl groups containing 16 carbon atoms and 60% to 75% containing 18 carbon atoms. The long chain alkyl group provide hydtophobic characteristic. In addition to long chain carbon molecule the other groups that are attached to the cation centers are divided into two classes viz. (i) Filler groups and (ii) Active groups

The filler groups are small chain alkyl radicals that complete the tetrahedron around the nitrogen. It does not offer any beneficial effects to the organoclay performance. The typical examples of filler groups are hydrogen and short chain alkyl groups viz methyl, ethyl, butyl.
The active groups which is a small part of the total cation, have a beneficial contribution to the organoclay performance. Typical examples of active groups are benzyl and 2 hydroxy ethyl. The cations containing these groups will not significantly increase the basal spacing between the clay platelets but provide both greater solvent polarity range and improved ease of dispersion to the organoclay.
Anions such as Cl , Br , acetate, hydroxide, nitrate, nitrite, etc may be present in the quaternary ammonium compound to balance the charge of cation. Generally salt having Cl , Br or mixture of them as anion is selected These quaternary ammonium salts can be represented by the formula
where RI and RT are methyl groups. RS is the aryl group and R4 is the long chain alkyl group containing a mixture of 12 to 22 carbon atoms wherein the major portion is of C|6 -C|g carbon atoms. This alkyl chain has 20% to 30% have 16 carbon atoms and 60% to 75% have 18 carbon atoms, based on 100% and where X " is preferably selected from the group consisting of Cl Br . NO.i .OH . (MhO: and mixtures thereof.
In accordance with the present invention it has been found that organically modified clay complexes can be prepared by introducing a dilute solution of quaternary ammonium salt (such as dimethyl alkyl aryl ammonium chloride) to a dilute aqueous dispersion of clay (montmorillonite and the like) that has been, prior to reaction with quaternary ammonium salt converted to homoionic form. The reaction can be represented by the general formula

In the present invention, the starting material or reactants employed include bentonite clays and quaternary ammonium compounds (cationic surfactant). As used herein, the bentonite clay is in the highly purified state with major portion being montmorillonite clay. It is particularly advantageous because montmorillonite in pure form possesses high swelling power and base exchange capacity. The montmorillonite clay is effective/suitable in high cation exchange capacity, in which the exchange capacity must be in the range of 60 to 100 millicquivalents per 100 grams of clay. The swelling capacity in water must be about 20 times than the original volume of raw clay.
The commercially available quaternary ammonium compound is used, which is completely soluble in water. It contained atleast one long chain alkyl group containing atleast 12 carbon atoms. The other groups attached to the cation may be (i) "Filler" group which serves to complete the tetrahedron around the nitrogen and (ii) The "Active" group (Aryl group) which contributes to organoclay performance by providing greater solvent
polarity and improved ease of dispersion. The cations must have sufficient hydrophobic character to impart organophilic character to the modified clay reaction product. The preparation of organically modified clay complexes such as is contemplated by this invention is accomplished by first dispersing a naturally occuring clay lumps/powder, in demineralized water to produce a dilute slurry. This dilute clay slurry is then subjected to separation / upgradation process which causes the removal of non-clay contaminants from the montmorillonite clay particles. This separation can be readily accomplished by permitting the contaminants to settle out of a dilute aqueous dispersion of the clay or they can be removed by hydrocyclone or centrifugation techniques. This step may be conveniently carried out either before or after converting the clay into a desirable homoionic form.
Many of the non-swelling bentonitc clays exhibit in their natural state the base exchange capacity satisfied w ith Ca+" and Mg*~ which are comparatively difficult for organic cations to replace. It has been found that a much improved organically modified clay complexes can be prepared by subjecting the clay to an ion-exchange treatment to replace Ca+2 and Mg+" ions by sodium or any monovalent ion. prior to reacting it with quaternary ammonium compound of the type described.
In commercial practice, one of the most widely used methods for preparing a homoionic clay is by passing a dilute clay slum.' through an ion-exchange resin column using a fixed bed technique. Other method in which clay slurry is mixed with resin under agitation can also be used to prepare homoionic clay. In the practice of this invention, another method of preparing homoionic clay which can be employed is by repeatedly leaching the clay slurry with a solution of water soluble metal salt or acid and subsequently washing the clay free of excess salt.
In general, the ion-exchange reaction between the charge balancing cations of the clay and cations of quaternary ammonium salts can be carried out over a wide range of temperature. According to this invention, the improved characteristics i.e. high degree of hydrophobicity ( high retention of organic cations on clay ) is obtained when the reaction as hitherto described is carried out at a temperature within the range of 35°C to 75°C or higher, although it was observed that there is no particular advantage in higher reaction temperature. It is understood that high degree of hydrophobicity depends significantly upon the selectivity of organic cation in the interlayer space of clay, in place of inorganic charge balancing cations. Such selectivity for organic cation is related to the easy availability of organic cations in solution which is temperature related. The interaction at controlled temperature leads to the production of modified clay complexes having higher hydrophobicity and required surface characteristics. In so far as the temperature of dispersed clay slum- is concerned, it is not critical and it may be delivered at room temperature or higher as per the objective of the invention.
In accordance with the broad aspect of the present invention, the ion-exchange reaction having particular regard to the co-mingling of the total quantities of the two reactants, is subject to a variety of approaches. The total quantities of the reactants can be co-mingled very rapidly or very slowly, in both the cases the ion-exchange reaction will take place. In practising this invention, it is found desirable not to complete the addition of quaternary ammonium salt solution in a period of time shorter than 30 minutes. Moreover, it may be mentioned here that little or no advantage is gained by unduly prolonging the addition time. In no instance, it is found to be desirable to extend the addition time, beyond a period of about 70 minutes. A more suitable range for producing the
organoclay with high hydrophobicity is from about 30 to 40 minutes, besides the aging
time, before the flocculated clay is filtered. In this invention it is not found to be advantageous to disregard the rate of co-mingling of readmits, because the uniformity of the particulate mass composing the end product is rendered poor or economics is adversely affected.
According to this invention, number of conditions are varied, as directed above to obtain modified organoclay with improved surface properties. One such important aspect of the present invention involves the clay concentration and molar concentration of quaternary ammonium salt solution. For those skilled in the art of manufacture of organoclay, it is understood that a dilute aqueous dispersion of clay must be present as a part of the reaction medium right from the inception of the reaction, otherwise the end product fails to acquire the physical / surface characteristics falling within the specified range. In practising this invention, the raw clay is dispersed in demincraliscd water at a concentration from about 1 to 5 percent by weight. The slurry optionally sedimented / hydrocycloned and / or centrifuged to remove non-clay impurities which constitute about 30 to 40 percent by weight of the starting clay composition. Thus, the purified clay slurry contains montmorillonite clay, within the range of about 0.5 to 4.0 percent, particularly and preferably in the range of about 1 to 3 per cent. At lower concentration, degree of hydrophobicity or in other words the retention of organic cations by the clay, is higher. At higher concentration, the organophilic clays are poor gellants. The quaternary ammonium salt solution is prepared containing organic cations within the range of about 0.01 M to 0.1M, preferably in the range of about 0.02 M to 0.07M. It is further found in this investigation that dilution of quaternary ammonium salt does not help in improving the surface properties of the end product. At the same time, increasing the concentration beyond a certain limit, no advantage
is gained.
In practising this invention the quaternary ammonium salt solution is prepared in the desired milliequivalent ratio, either dispersed or dissolved in demineralised water.The amount of quaternary ammonium salt added to the clay must be sufficient to impart to the organophilic clay the enhanced gellation characteristics desired. The milliequivalent ratio is the number of milliequivalent of the quaternary ammonium compound in organophilic clay per 100 grams of clay. The modified organoclay complexes of this invention have a milliequivalent ratio from 90 to 110. At lower milliequivalent ratio, the organophilic clays are ineffective gellants. even though they may be effective gellants in presence of a polar additive. At higher milliequivalent ratio the organophilic clay are poor gellants. However, the preferred milliequivalent ratio within the range from 90 to 110 will vary depending on the characteristics of the organic system to be gelled by the organophilic clay. Upon completion of the addition of the quaternary ammonium salt solution and given the sufficient aging time for the ion-exchange reaction to be completed, the flocculation of organically modified clay complexes takes place. The latter readily separated from the aqueous phase by filtration, but other means of separation, such as centrifuge / filter press can be used. It is preferable to wash the product with demineralised water to remove adhering water soluble salts and the like. The filter cake is then dried in an air-circulated oven. The amount of water remaining in the powder depends upon the time, temperature and other conditions of drying. The dried cake can be pulverised to produce a fine pulverulent product with the help of a hammer mill.
A simple gel volume measurement method has been adopted to illustrate the compatibility (dispersion) of organophilic clay prepared in this invention. In this method, 2 grams of organophilic clay is slowly added to a toluene-methanol mixture (80 : 20 by
volume) taken in a 100 ml graduated stoppered glass cylinder and thoroughly shaken to
uniformly disperse the clay. The volume of gel in millilitres is recorded after 24 hours. The milliequivalents of the organic compound retained in the organophilic clay is calculated from the ignition loss at 800°C of (i) clay-organic complex (ii) hydrophilic upgraded clay and (iii) molecular weight of quaternary ammonium cation. The free moisture is measured by keeping the sample in oven at 105°C for 2 hours The product so obtained has the following properties :(Table Removed)
In the present invention, bentonite clay having (i) basal spacing in the range of 12-16A0 (ii) cation exchange capacity in the range of 60 to 110 milliequivalents per 100 grams of dry clay, (iii) swelling capacity in water more than 20 cc.. was used The bentonite with above properties should have Silica (as SiOi ) 45-55 %: Alumina (as AN O.i ) 20-25 %; Iron oxide (as Fe: O.; ) 7-12 %: Magnesium oxide ( as MgO) 2-4 %; Sodium oxide ( as NaaO)
1-3 % and Calcium oxide (as CaO) 1-4 %. The impurities (non-clay fractions) were removed
by sedimentation /centrifugation technique. Different homoionic forms viz. Na and H were prepared either by using ion-exchange resin or concentrated inorganic salt solution. The typical quaternary ammonium compounds which have been used in the practice of this invention includes (i) Dimethyl benzyl stearyl ammonium chloride (ii) Dimethyl benzyl cetyl ammonium chloride, (iii) Dimethyl dioctadccyl ammonium chloride, (iv) Dimethyl dihydrogenated tallow ammonium chloride. Any of the above compounds can be used with an ion-exchange treated clay to produce an organically modified clay complex. The molecular weight of these organic compounds ranged from 390 to 590. Using the above organophilic clay the grease may be prepared from lubricating oil having the following

properties. (Table Removed)
Now in accordance with the present invention it has been found that no special equipment is required in the process herein described. The reaction vessel should be equipped with an adequate agitator which produces a strong back flow of slurry and avoids zone of high concentrations of the reactants. The storage vessels for (i) purified clay slurry and (ii) quaternary ammonium salt solution, are connected to the reaction vessel through lines fitted with flow control means. The reaction vessel is equipped with an outlet line fitted at the bottom leading to a filter which may be of the plate and frame type or a
centrifuge. The filter cake is washed with water until the test for chloride is negative with silver nitrate. The filtered and washed mass is dried in air circulated tray dryers. This method of preparation generates a very dilute effluent which contains soluble salts and very less quantity of unreacted organic cation. The effluent is acidic in nature and can be neutralised by a small amount of alkali., before its disposal.
In the present invention, an improved organophilic clay gellants are prepared from a purified clay slurry and a clear solution of quaternary ammonium sail. The process imbibes a simple ion-exchange reaction between the interlayer inorganic cations of clay and the organic cations of quaternary ammonium salt, under ambient and experimental conditions. The organo-clay so prepared possess a high degree of hydrophobicity. The byproduct such as sodium chloride is removed by washing. In this method, the simple inventive steps adopted are (i) dispersing the bentonite clay demineralised water without the use of dispersing agents; (ii) the purified clay slurry so obtained is used as such and does not need homogenisation at high pressure ; (iii) the homo-ionic clay is prepared by addition of dilute mineral acid ; (iv) the quaternary ammonium compounds are readily soluble in hot water and (v) the basic ion-exchange reaction is carried out at ambient temperature. The clay used in this process, have sites in the interlayer space, where the exchange of ions takes place. This space can be expanded and organic cation of large molecular size can be accomodated. The organic cations orient in mono-, di-. or pseudo layer depending on the experimental conditions. The quaternary ammonium compound used in this process have an active group with a hydrophobic character which is found to be responsible for the conversion of hydrophilic character of clay to hydrophobic character.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
EXAMPLE 1
An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry were removed by sedimentation and / or hydrocyclonc techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grains of clay. The slurry, which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid. This H-form of the clay slurry was kept at room temperature and a solution of dimethyl benzyl stearyl ammonium chloride prepared in hot (70°C)-demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product.
EXAMPLE 2
An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as detennined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and /or hydrocyclone techniques. After purification,
the base exchange capacity was found to be about °o milliequivalent per 100 grams of clay.
The slurry which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-form of the clay slurry was kept at room temperature and a solution of dimethyl benzyl cetyl ammonium chloride prepared in hot (70°C) demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product.
KXAMI'LK 3
An aqueous clay slurry .of Akli bentonite collected from Barmer district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 millicquivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and / or hydrocyclone techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grams of clay. The slurry which contained about 1 weight % ( weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-form of the clay slurry was kept at room temperature and a solution of dimethyl dioctadecyl ammonium chloride prepared in hot (70°C) dimineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulverized to obtained a finely powdered product.
EXAMPLE 4
An aqueous clay slurry, of Akli bentonite collected from Banner district of Rajasthan, India, was prepared in demineralised water containing about 1.7 % raw clay by weight. This raw clay had a base exchange capacity of about 75 milliequivalents per 100 grams of clay as determined by ammonium acetate method. The non-clay fractions (impurities) in clay slurry was removed by sedimentation and / or hydroc) clone techniques. After purification, the base exchange capacity was found to be about 95 milliequivalent per 100 grams of clay. The slurry which contained about 1 weight % (weight by volume ) of clay was brought to hydrogen-form by adding dilute mineral acids like hydrochloric acid . This H-lbrm of the clay slurry was kept at room temperature and a solution of dimethyl dihydrogenated tallow ammonium chloride prepared in hot (70°C) demineralised water was added in 45 minutes to the agitated clay suspension. The reaction mixture was agitated continuously for another 60 minutes. The well flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demineralised water, dried at 65 °C in air circulated oven and pulveri/ed to obtained a finely pondered product.
The preliminary properties of these organophilic clays prepared so far. are shown in Table 1 The results shows the improved compatibility (dispersion) of organoclay with organic solvents and better retention of quaternary ammonium compound on clay surfaces. The data in Table 1 indicates the increase in the ease of dispersion of organophilic clay prepared from dimethyl benzyl stcaryl ammonium chloride and montmorillonite clay when the amount of this quaternary ammonium chloride was in the range of 90 to 110 milliequivalents per 100 grams of clay. The data also depict better retention characteristics of organic cation on clay surface as compared to organophilic clays prepared from somewhat similar
but different quaternary ammonium compounds.
TABLE - 1
(Table Removed)
ME=milliequivalent.
EXAMPLE 5
An aqueous clay slurry of Hathi-Ki-Dhani bentonite powder collected from Jodhpur district of Rajasthan, India was prepared in demineralised water containing 1.7 % raw clay by weight. This raw clay had a base exchange capacity of 60 milliequivalent per 100 grams of clay and a swelling capacity of 32 cc in demineralised water. The clay was purified by subjecting the clay slurry to sedimentation and siphoning the clay fractions. After the purification step, the clay had a base exchange capacity of 93 milliequivalent per 100 grams of clay and the swelling capacity was 36 cc. The clay slurry which contained 1 weight %
(weight by volume) of clay was brought to hydrogen form by adding dilute hydrochloric acid. This H- form of clay slurry was kept at room temperature and a solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) dimineralised water was added in 45 minutes to the agitated clay suspension. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to and more than the base exchange capacity of clay. The reaction mixture was agitated continuously for another 60 minutes. The well-flocculated organically modified clay complex formed as a result was filtered by known methods, washed with demincralised water, dried at 65 ° C in air circulated oven and pulverized to obtained a finely powdered product. The properties of this organophilic clay are shown in Table 2.
TABLE 2

(Table Removed)
ME = milliequivalent EXAMPLE 6
The Akli bentonitc lumps collected from Banner district of Rujasthan , India, was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of
clay slurry at 35° C and under continues stirring an aqueous solution of dimethyl benzyl stearyl ammonium chloride, separately prepared in hot (70°C) dcmineraliscd water was added in 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The flocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65° C . The granules were pulverized to obtain fine powder.
The organophilic clay prepared above was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly.
EXAMPLE 7
The Akli bentonite lumps collected from Banner district of Rajasthan .India, was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35" C and under continuous stirring an aqueous solution of dimethyl benzyl cetyl ammonium chloride separately prepared in hot (7()°C) demineralised water. wras added in 45 minutes. The amount of dimethyl benzyl cetyl ammonium chloride added was just
equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The ilocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65" C . The granules were pulverized to obtain fine powder.
The organophilic clay prepared above was used as gellants at a concentration of 9% by weight inmineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpin. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an AS'I'M grease worker assembly
EXAMPLE 8
The Akli bentonite lumps collected from Banner district of Rajasthan India .was dispersed under strong agitation for 2 hours in demineralized water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grains of clay. The clay was converted to homoionic form by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35° C and under continuous stirring an aqueous solution of dimethyl dioctdecyl ammonium chloride separately prepared in hot (70°C) demineralised water was added in 45 minutes. The amount of dimethyl dioctadecyl ammonium chloride added was just equivalent to the base exchange capacity of clay. The reaction mixture was agitated for another 45 minutes. The Ilocculated organoclay complex was filtered by known methods, washed with
demineralised \\ater and dried at 65'V . The granules were pulveri/ed to obtain fine powder.
The organophilic clay prepared above was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly.
EXAMPLE 9
The Akli bentonite lumps collected from Banner district of Rajasthan. India .was dispersed under strong agitation for 2 hours in demineralised water at a concentration of 17 g clay per litre and purified by sedimentation and / or centrifugation method. This purified clay had a base exchange capacity of 95 milliequivalent per 100 grams of clay. The clay was converted to homoionic fonn by adding dilute hydrochloric acid. While maintaining the temperature of clay slurry at 35" C and under continuos .stirring an aqueous solution of dimethyl dihydrogenated tallow ammonium chloride separately prepared in hot (70°C) demineralised water was added in 45 minutes. The amount of dimethyldihydrogenated tallow ammonium chloride added was just equivalent to the base exchange capacity of clay.The reaction mixture was agitated lor another 45 minutes. The flocculated organoclay complex was filtered by known methods, washed with demineralised water and dried at 65 ° C . The granules were pulverized to obtain fine powder.
The organophilic clay prepared above was used as gellants at a concentration of 9% by weight inmineral oil in presence of 0.8% propylene carbonate, a polar organic dispersant. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer
rotating at 450 rpm. A polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, alter setting for 24 hrs were obtained for unworkecl and after working the grease for 50 strokes in an ASTM grease worker assembly. The results are shown in Table 3. .
TABLE-3
(Table Removed)
ME = milliequivalents EXAMPLE 10
The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand lor 24 hours (sedimentation) so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay.This clay shiny was converted to hydrogen
form by adding dilute hydrochloric acid. This clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtain fine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.2% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was then added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly.
EXAMPLE 11
The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand for 24 hours (sedimentation) so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had an cation exchange capacity of 95 milliequivalcnt per 100 grams clay. This clay slurry was converted to hydrogen form by adding dilute hydrochloric acid. 1 his clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride

separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was. 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 °C. The granules were pulveri/cd to obtainfinc powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.4% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was thru added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly.
EXAMPLE 12
The Akli bcntonitc lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dimineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slum' was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay slurry was converted to hydrogen form by adding dilute hydrochloric acid. This clay slurry at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) demineralised water under continuous stirring. The total time of addition of this
organic moiety solution was 45 minutes. The amount of dimethyl ben/yl stearyl ammonium
chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulveri/ed to obtainfine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.6% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly.
EXAMPLE 13
The Akli bentonite lumps, collected from Banner district of Rajasthan, India was dispersed under strong agitation in dcmineraliscd water for 2 hours at a concentration of 17 g clay per liter. Then the clay slum' was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slum' (1% by wt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay slum- was converted to hydrogen form by adding dilute hydrochloric acid. This clay slum1 at room temperature (35"C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70"C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was

filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtainfine powder. This organoclay was used as gellants at a concentration of 9% by weight in mineral oil in presence of 0.8% propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrcr rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogeniser with a mill gap or a rotator to stator clearance of 0.008 inch. The AS I'M penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly EXAMPLE 14
The Akli bentonite lumps, collected from Banner tlistrict of Rajaslhan. India was dispersed under strong agitation in demineralised water for 2 hours at a concentration of 17 g clay per liter. Then the clay slurry was allowed to stand for 24 hours so that silt, sand, and non-clay fractions settled at the bottom. The clay containing slurry (1% by \vt) was siphoned and was collected in a separate reaction vessel. This clay had a cation exchange capacity of 95 milliequivalent per 100 grams clay. This clay shiny was converted to hydrogen form by adding dilute hydrochloric acid. This clay slum- at room temperature (35°C) was reacted with an aqueous solution of dimethyl benzyl stearyl ammonium chloride separately prepared in hot (70°C) demineralised water under continuous stirring. The total time of addition of this organic moiety solution was 45 minutes. The amount of dimethyl benzyl stearyl ammonium chloride added was just equivalent to the base exchange capacity of the clay. The reaction mixture was agitated for another 60 minutes. The flocculated organoclay complex was filtered by known methods, washed with dimineralised water and dried at 65 ° C. The granules were pulverized to obtainfine powder. This organoclay was used as gellants at a

concentration of 9% by weight in mineral oil in presence of 1.0 % propylene carbonate. The organoclay was slowly mixed with mineral oil in 45 minutes using a mechanical stirrer rotating at 450 rpm. The polar activator was than added and stirred for another 10 minutes. The resulting mass was then milled through a colloid mill or a homogcniser with a mill gap or a rotator to stator clearance of 0.008 inch.
The ASTM penetration index of the grease, after setting for 24 hrs were obtained for unworked and after working the grease for 50 strokes in an ASTM grease worker assembly. The results are shown below.(Table Removed)
The main advantages of the present invention are :
1. The bentonite clay, either in powder or lumps, can be readily dispersed in
demineralised water under strong simple agitation. It does not require any
dispersing agent.
2. The clay slurry after purification by known techniques is not required to be
subjected to homogenization under high pressure.
3. The homo-ionic form of the clay slurry can be easily prepared by simple
addition of mineral acid viz. hydrochloric acid.
4. The quaternary ammonium compounds are used in the present invention are
readily soluble in hot demineralised water.
5. The basic ion exchange reaction is carried out at ambient temperature (35° C).

We Claim:
1. A process for the preparation of organophilic clay useful as gellants for making
viscous organic systems which comprises
i) dispersing 2 to 3 weight percent of raw smectite clay selected from - fcfort t fanfr o twvdtt fyfftf f- hodfff rtbe£f f bentonite in dejnineralized water under stirring by known method, to
obtain a slurry, ii) purifying the said dispersed clay slurry by known methods to obtain
cation exchange capacity of 60 miliequivalent per 100 g clay and a water
swelling capacity of 20 cc, iii) converting the purified bentonite clay slurry to homoionic form by
reacting with concentrated alkali metal inorganic salt solution such as
herein described or hydrochloric acid or by passing the clay slurry
through the cationic form of ion exchange resin, iv) preparing a solution of quaternary ammonium salt in de mineralized
water at 70°equivalent to the cation exchange capacity of the purified
clay,
v) adding the quaternary ammonium salt solution as obtained in step (iv) to
the homo ionic clay slurry as obtained in step (iii) at room temperature
under constant agitation, allowing the reaction mixture to age under
stirring to obtained flocculated clay, separating the flocculated clay by
known methods, to obtain wet cake of organophilic clay, vi)drying the wet cake in an air circulated oven, while maintaining the
temperature at 65 °Celsius, until the free moisture is 3 percent;
(vii)pulverizing the dry granules in a steel hammer mill to obtain a organo
philic clay.
2. A process, as claimed in/claim 1, wherein the bejrfonite clay used are^in either lump
or powder form arid the purified clay/has a basal spacing o£-12-16 Axtfation
exchange capacity of 60 mill equivalent per/10-O) grams oi'clay andjsvater swelling
capacityn20cc.
A process, as claimed in claims 1 & 2, wherein the quaternary ammonium compounds used contains at least 12 carbon atoms in alkyl group with preferably 20

to 30% of alky group containing 16 carbon atoms and 60 to 75% of alkyl group containing 18 carbon atoms.
A process as claimed, in claims 1 to 3 wherein the dimethyl benzyl stearyl
ammonium compound solution is added to the clay slurry over a period of 30 to 70
minutes.
A process as claimed, in claims 1 to 4 wherein the reaction mixture is agedopo) a

I period of at least 45 minutes.
. A process as claimed, in claims 1 to 5 wherein the quaternary ammonium
compounds used are, (i) dimethyl benzyl stearyl ammonium chloride (ii) dimethyl
benzyl cetyl ammonium chloride (iii) dimethyl dioctaecyl ammonium chloride (iv)
dimethyl dehydrogenated tallow ammonium chloride.
7. A process asdaimed in claims 1 to 6, wherein the concentration of quaternary
ammopktmchloride solution are in the range ofOfto 0.1 molar. X? A process for the preparation of (Hauweve? organophilic clay useful as gellants for
making viscous organic systems substantially as herein described with references to the examples.
.

Documents:

572-del-2000-abstract.pdf

572-del-2000-claims.pdf

572-del-2000-correspondence-others.pdf

572-del-2000-correspondence-po.pdf

572-del-2000-description (complete).pdf

572-del-2000-form-1.pdf

572-del-2000-form-19.pdf

572-del-2000-form-2.pdf

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Patent Number

220178

Indian Patent Application Number

572/DEL/2000

PG Journal Number

28/2008

Publication Date

11-Jul-2008

Grant Date

16-May-2008

Date of Filing

09-Jun-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	BALESHWAR DAS MITTAL
2	RAJESH SHANTILAL SOMANI
3	ADITYA SHANTIBHAI MEHTA
4	KANTA PRASAD NAITHANI
5	DIPAK BALVANTRAJ SHUKLA
6	BATUKLAL JAYANTILAL BHALALA
7	SHARAD DATTATRAYA GOMKALE
8	MADAN MOHAN RAI
9	RAKSH VIR JASRA
10	AKHILESH KUMAR BHATNAGAR

PCT International Classification Number

B01J 13/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA