Title of Invention	METHOD FOR THE PRODUCTION OF A FINELY CRYSTALLINE BOEHMITE AND APPLICATION OF SAID BOEHMITE AS FLAME RETARDANT IN PLASTICS
Abstract	Method for the production of a finely crystalline boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 m3/g via autocatalytic, hydrothermal crystallisation and method for production of a crystalline seed for crystallisation via grinding of an aluminum monohydrate source at a pH-value in the range of 2 to 4 and application of boehmite as a flame retardant in plastic compositions.

Title of Invention

METHOD FOR THE PRODUCTION OF A FINELY CRYSTALLINE BOEHMITE AND APPLICATION OF SAID BOEHMITE AS FLAME RETARDANT IN PLASTICS

Abstract

Method for the production of a finely crystalline boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 m3/g via autocatalytic, hydrothermal crystallisation and method for production of a crystalline seed for crystallisation via grinding of an aluminum monohydrate source at a pH-value in the range of 2 to 4 and application of boehmite as a flame retardant in plastic compositions.

Full Text	FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 Provisional /Complete specification [See Section 10 and rule 13] 1 Title of the Invention. "Method for the production of a finely crystalline boehmite ar boehmite as flame retardant in plastics" id application of said 2 Applicant (s) Applicant Nabaltec AG Nationality GERMANY Address Alustr. 50-52, 92421 Schwandorf, Germany. The following specification particularly describes the invention and the manner in which it is to be performed. 1 METHOD FOR THE PRODUCTION OF A FINELY CRYSTALLINE BOEHMITE AND APPLICATION OF SAID BOEHMITE AS FLAME RETARDANT IN PLASTICS BACKGROUND 1. Technical Field: This application relates to a method for the production of a finely crystalline boehmite and application of said boehmite as flame retardant in plastics. 2. Background Information: From US 4,117,105 the conversion of aluminumtrihydrate to well dispersable boehmite is known. According to one method, aluminumtrihydrate with a BET-surface of 0,2 to 15 m2/g is calcined at temperatures between 200 up to 800°C for 2 to 17 hours, until the BET-surface has risen to 250 to 800 m2/g. The Brunauer-Emmett-Teller (BET) method is a method of measuring the amount of gas absorbed on a solid surface. Then a slurry of the calcined alumina is rehydrated at a temperature of 140 to 200DC for 0,5 to 6 hours in an autoclave. A flame retardant plastic composition and a method for producing a filler material is known from German Patent No. 19812279 C1. The plastic composition consists of 55 to 75 % boehmite in an orthorhombic crystal structure, wherein, depending on temperature control, the BET-surface varies between 14,75 and 17,25 m2/g. As filler material boehmite with a grain diameter of 0,5 up to 3 micrometer is applied. From German Patent No. 69231902 T2 a method for the growth of crystals, especially crystals consisting of metal oxides, at increased speed is known. In said method BET-surfaces in a range of 40 m2/g at a crystal size of roughly 50 nm are obtained. Within said method a feed solution with a pH-value of 3 to 11 is provided for precipitation on a seed crystal, which comprises a metal oxide species, which is 2 sufficiently insoluble in the aqueous medium, in order to provide a solid center of growth. The treatment is then carried out under hydrothermal conditions, wherein feed material is added until the end of crystal growth. In Japanese Patent No. 63265810 A a method is described, in which smooth ct-Al203-spheres are obtained from an aluminumhydrate, wherein aluminumhydrate is ground in wet condition at a pH-value between 1 and 4. Said a-AI203 is obtained subsequently by calcination at 1350 to 1500°C. From the production of the ion conductor beta-alumina, it is known from German Patent No. 3617115 A1 to mix boehmite with water and to adjust the pH-value of the mixture with acetic acid to a pH-value of 4. The mixture is then ground and sodium oxide and a spinel-stabilizator are mixed into the ground mixture in aqueous solution whereafter the solution is peptised, e.g. by acidifying anew to a pH of 4 with acetic acid and the following, production of a gel at raised temperatures (80°C for 20 minutes). The product can preferably be formed into a self-supporting commodity, consisting of beta-alumina, by isostatic pressing. A method for the production of quasi-crystalline boehmite from a boehmite-precursor by application of seed crystals in hydrothermal treatment is known from German Patent No. 60015345 T2. Also ground boehmite crystals can be applied as crystals, wherein the hydrothermal reaction is carried out at pH-values equal or smaller than 7. Furthermore the production of microcrystalline boehmite and ceramic bodies is described in German Patent No. 3879584, wherein a precursor of boehmite and boehmite seed crystals are applied under hydrothermal conditions at pH-values of 8 or higher and temperatures of above 130°C. A method for the production of finest-particulate seed crystals is known from United States Statutory Invention Registration H189, published January 6, 1987. With said seed material alpha alumina is obtained by 3 applying the seed material in a boehmite-gel and transformation at relatively moderate temperatures into finely crystalline alpha alumina. Said material is applied within electrical industrial production or as abrasive. For the application in flame retardants in plastic compositions a finely crystalline boehmite is required, having a low surface and a low pore volume. The flame retardant should show good and easy miscibility with said plastic compounds while having a high fraction at the total composition and also a high level of inflammability or non-flammability should be obtained. Furthermore the properties of mechanical strength like tensile strength and elongation at break should be on a high level. OBJECT OR OBJECTS An object of at least one possible embodiment of the present application is to provide a method for production of fine crystalline boehmite having a low surface and a low pore volume, which is easily miscible into plastic compounds at a high fraction of the total composition and provides a high level of inflammability or non-flammability while enabling excellent properties of mechanical strength. SUMMARY At least one possible embodiment of the present application is a method for production of fine crystalline boehmite having a low surface and a low pore volume, which is easily miscible into plastic compounds at a high fraction of the total composition and provides a high level of inflammability while enabling excellent properties of mechanical strength. According to at least one possible embodiment of the present application, a fine-crystalline boehmite is provided having an average grain diameter of D50 (D50 = the 4 median diameter) in the range of 50 to 400 nm in one embodiment, in the range of 100 to 300 nm in another embodiment, or in the range of 150 to 250 nm in yet another embodiment. Furthermore the micro-particulate boehmite has a BET-surface in the range of 10 to 40 m2/g, more preferably 15 to 35 m2/g, most preferably 15 to 30 m2/g. In a further embodiment the boehmite has a pore volume in the range of 0,05 to 0,5 cm3/g, especially preferred 0,1 to 0,4 cm3/g. According to at least one possible embodiment of the present application, the predescribed fine-crystalline boehmite with low surface is produced from a hydrate source by the method of autocatalytic, hydrothermal crystallization. Autocatalytic generally describes a reaction in which the reaction product itself is a catalyst for the reaction. Hydrothermal generally describes a technique for crystallization of substances from higher temperatures at higher pressures. The method will be described in the following. According to the embodiment hereof, it is essential or highly desirable during implementation of the method to apply a special type of seed crystal. The properties of the type of seed crystal as well as a method for its production are explained in detail in the following. For the production of the embodiment of the seed crystal an aluminummonohydrate source is used. The aluminummonohydrate source (AIO(OH)) is of boehmitic crystal structure and has an appropriate particle size with a D50 grain size of about 500 nm or larger as well as a BET-surface of 20 m2/g or larger. Such aluminummonohydrate sources can be obtained in trade for example under the commercial designation APYRAL produced by Nabaltec Co. Germany, located at Nabaltec AG, Alustrasse 50-52, 92421 Schwandorf, Federal Republic of Germany. Subsequently an aqueous dispersion is produced from the aluminummonohydrate source and said dispersion is ground, preferably in a ball-mill. A 5 ball mill is generally a type of mill that uses either balls or pebbles, usually ceramic, to reduce a wet or dry material down to specified size by grinding the material with the balls or pebbles. Surprisingly it turned out that during grinding of the aluminummonohydrate source in an aqueous suspension at a pH-value in the range of 2 to 4 in one embodiment, in the range of 2.5 to 4.5 in another embodiment, or even at a pH-value of 3 in yet another embodiment, the BET-surface and the pore volume increase only slightly when compared to grinding in neutral or slightly basic dispersion. Organic acids, especially acetic acid, turned out to be especially appropriate. It may be assumed that organic acids promote the creation of smooth fractured surfaces during tribochemical reaction, which takes place during grinding between the grinding gear, the dispersion liquid and the fracturing surface of the boehmite. Tribochemistry is generally defined as a field of chemistry that focuses on chemical reactions occurring on the surface of an object or substance. Acetic acid showed in a sequence of experiments an optimal or desirable combination of acid strength, stability, solubility of its salts and miscibility with water. The stronger acids like formic acid or oxalic acid, tended to decompose at higher reaction temperature while organic acids with longer carbon chains, which are less miscible with water, like pentane- and hexane-acid showed a considerably decreased velocity of reaction and produced salts which are hardly soluble. With the application of acetic acid while keeping the reaction temperature between 50°C and 70°C a quick transformation and grinding could always be carried out, without the acetic acid decomposing or producing insoluble salts to an undesirable or unacceptable degree. 6 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the evolution of the BET-surface in relation to the duration of grinding for 3 crystalline precursor boehmites; Figure 2 shows a comparison of the evolution of BET-surface in relation to the duration of grinding for a time span of 180 minutes, wherein a dispersion having a pH-value of 9 and second dispersion having a pH-value of 4 are compared; and Figure 3 shows the results of the determination of the evolution of pore volumes during the experiments of Figure 2. i ■ DESCRIPTION OF EMBODIMENT OR EMBODIMENTS Figure 1 displays the evolution of the BET-surface in relation to the duration of grinding for 3 crystalline precursor boehmites as described in table 1. The results of a grinding according to a known process in neutral aqueous dispersion are shown. The concentration of solids was 10 % in relation to the boehmitic aluminummonohydrate-source. Table 1 shows the average grain size as well as BET-surface of the applied precursor substances prior to grinding. The determination of the BET-surface was carried out according to DIN 66131; likewise the following BET-values (DIN = German Industrial Standard). table 1 D50 (nm) BET (m'/g) commercial designation 3000 10 AOH 103 1300 10 AOH 104 600 20 AOH 180 7 As can be seen from Figure 1, the BET-surface increases for all 3 precursor boehmites as could or should be expected with increasing duration of grinding and the respective decrease of the size of the crystals. The course of evolution of the BET-surface in relation to the duration of grinding at a maximum duration of grinding of 3 hours (180 minutes) is demonstrated. The dispersion of the precursor-boehmites has a pH-valueof 9. Figure 2 shows a comparison of the evolution of BET-surface in relation to the duration of grinding for a time span of 180 minutes, wherein a dispersion having a pH-value of 9 and second dispersion having a pH-value of 4 are compared. It can be seen from this figure that the increase of BET-surface is significantly less for the acidic dispersion. In both comparative experiments boehmite of the type AOH 180 according to Table 1 was applied. Figure 3 shows the results of the determination of the evolution of pore volumes during the experiments of Figure 2. It is obvious that the pore volume in the acidic dispersion increases during grinding little or surprisingly little, while the pore volume of the commonly prepared dispersion increases considerably. The determination of the pore volume was carried out according DIN 66134 via nitrogen-sorption at 77 K with 99,99% pure, dry nitrogen; all following pore volumes likewise. The pore volume was determined from the nitrogen adsorption or nitrogen desorption branch respectively of the isotherms according to Gurwitsch. Further experiments with varied concentration of solids of boehmitic aluminummonohydrate source confirmed the situation depicted in Figure 3. With a solid fraction, concerning the boehmitic aluminummonohydrate source, in the range of 5 to 50% in one possible embodiment or in the range of 10 to 25% in another possible 8 embodiment, the described change of pore volume in acidic dispersion could always or usually be found. Furthermore the temperature of the dispersion was kept in a range of 50 to 70°C in one possible embodiment or at a temperature of 60°C in another possible embodiment, during grinding. The cooling of the dispersion can be carried out with known cooling-facilities. If the heat generated during a grinding reaction is removed via cooling and the temperature is kept between 50 and 70°C, the amount of water evaporized during grinding is negligibly small. If temperature peaks of 80°C or more occur during grinding, for example, the water content may be controlled at intervals of 10 minutes and water may have to be refilled as needed. With a grinding reaction at 60°C a dispersion can often be ground for several hours without the refilling of water becoming necessary. Especially when applying organic acids the amount of evaporized acid is generally so little, that ignitable mixtures of acids and air are generally securely prevented. The obtained product is applied as seed crystal for hydrothermal synthesis of boehmite in the following. When the grinding has reached completion the dispersion can be applied directly as a dispersion of seed crystals. In the following, the method for the production of the fine-crystalline boehmite with low surface via autocatalytic hydrothermal crystallization with application of the previously described boehmite-seed crystal is explained. For carrying out the autocatalytic hydrothermal crystallization, an alkaline aqueous dispersion is provided, comprising an applicable hydrate source such as (AI(OH)3) as well as the previously described type of embodiment seed crystal. The hydrate source which is produced from a dispersion, has a grain size distribution D50 of 0,5 to 100 micrometer in at least one possible embodiment, 0,5 to 10 micrometer in 9 another possible embodiment, or 0,5 to 2 micrometer in yet another embodiment. The concentration of the hydrate source in the dispersion is normally adjusted to 10 to 500 (g/l) in at least one possible embodiment, 50 to 150 (g/l) in another possible embodiment, or 90 to 110 (g/l) in yet another possible embodiment. The concentration of the sodium hydroxide solution within the dispersion can be 4 to 50 in one possible embodiment, 30 to 40 (g/l) in another embodiment in relation to free Na20. The concentration of solids concerning the seed crystal is generally adequately set to 0,5 to 50% in one possible embodiment, 1 to 20% in another possible embodiment, or even 5 to 15% in yet another possible embodiment, each in relation to the hydrate source. The autocatalytic hydrothermal crystallization of the previously described dispersion is carried out in an adequate autoclave. The reaction temperature is within a range of 110 to 180°C in at least one possible embodiment, within a range of 120 to 150°C in another possible embodiment, or even within a range of 125 to 135°C in yet another possible embodiment. The reaction time is between 4 up to 24 hours depending on the rate of consumption of the hydrate source. In one possible embodiment, the method can be carried out in a chemiclave, which is a specific type of autoclave. A type of chemiclave is manufactured by Alpha Multiservices, Inc. 706 Brook Hollow Dr., Conroe, TX 77385-9109, U.S.A. The production of the embodiment type of seed crystal as well as its advantages compared to the known process as well as the production of the embodiment boehmite via autocatalytic, hydrothermal crystallization while applying the previously introduced type of seed crystal, will be explained further in the following examples. 10 Example 1: Production of an embodiment type of seed crystal 300 g of a finely crystallized aluminummonohydrate with a specific surface of 20 m2/g and an average grain diameter D50 of 500 up to 600 nm (obtainable by the commercial designation APYRAL AOH 180, fabricated by Nabaltec Co. Germany) were dispersed in 3 l(liters) water using a laboratory stirring unit. Said dispersion was adjusted to a pH-value of about 3 via the addition of acetic acid and was ground in a laboratory ball-mill. A ball-mill of the type (PML HA/) of the company Drais, located at 40 Whitney Road, Mahwah, New Jersey, 07430, was applied. As grinding media milling balls of 300 to 400 micrometer diameter made from yttria stabilized zirconia were applied. The dispersion was ground for up to 3 hours. (Yttria = yttrium oxide, Y203) The temperature was kept at 60°C. Samples were taken from the initial substance as well as after 30 min., 60 min. and 180 min. of grinding. Table 2 shows the important parameters of the resulting products. table 2 duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size(D50)nm* initial ApAOH180 20 0,03 500-600 30 min ApAOH180_0,5h_pH3 33 0,05 400-500 60 min ApAOH180Jh_pH3 42 0,07 300-400 180 min ApAOH180_3h_pH3 50 0,08 200-300 * optically determined via SEM-picture (SEM = scanning electron microscope) 11 Example 2: -Comparative Example- 300 g of a finely crystallized aluminummonohydrate with a specific surface of 20 m2/g as in Example 1 were dispersed in water with a laboratory stirring unit. Said dispersion was ground in a laboratory ball-mill at a pH-value of about 9. As grinding media milling balls of 300 up to 400 micrometer diameter were applied. The dispersion was ground for up to 3 hours. Samples were taken of the initial substance as well as after 30 min., 60 min. and 180 min. of grinding. Table 3 shows the important parameters of the resulting products, table 3 duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size(D50)in nm* initial ApAOH180 20 0,03 500-600 30 min ApAOH180_0,5h 40 0,10 400-500 60 min ApAOH180_1h 54 0,14 300-400 180 min ApAOH180_3h 83 0,23 200-300 * optically determined via SEM-picture Example 3: -Comparative Example- 300 g of a finely crystallized alumniummonohydrate with a specific surface of 6 m2/g (obtainable by the commercial designation APYRAL AOH 60 Nabaltec Co. Germany) were ground with a laboratory ball-mill as in Example 1 but at a pH-value of 9. As grinding media milling balls of 300 up to 400 micrometer diameter of yttria stabilized zirconia were applied. The dispersion was ground for up to 3 hours. 12 Samples were taken of the initial substance as well as after 30 min, 60 min and 180 min of grinding. Table 4 shows the important parameters of the resulting products, table 4 duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size (D50)nm* initial ApAOH60 6 0,01 1000 60 min ApAOH60_1h 44 0,09 600-700 120 min ApAOH60_2h 65 0,14 400-500 180 min ApAOH60_3h 78 0,17 200-300 * optically determined via SEM-picture The comparison of the Examples 1 to 3 shows directly the advantages of the embodiment type of seed crystal as well as of its method of production. The embodiment Example 1 shows that starting from a commercially obtainable boehmite with a grain size diameter D50 of 500 to 600 nm and a BET-surface of 20 m2/g a seed crystal can be obtained with a targeted grain size of 200 up to 300 nm while at the same time the BET-surface as well as the pore volume increase only moderately. In direct comparison with comparative Example 2, starting with identical boehmite as precursor, according to the known process a considerably larger BET-surface as well as considerably larger pore volumes are obtained when the targeted grain size is reached. Even if a boehmite with a decreased BET-surface is used as a precursor, the production of the seed crystal according to the known process obtains a considerably larger BET-surface when reaching the targeted grain size of 200 up to 300 nm. 13 Example 4: -Comparative Example- Preparation of a seed crystal dispersion on the basis of a commercial pseudo boehmite. 100 g of amorphous aluminummonohydrate with a specific surface of 261 m2/g and a particle size D50 of 37 micrometer as well as a pore volume of 0,37 cm2/g (obtainable by the commercial designation Plural SB, fabricated by Condea Chemie Co. Germany, located at Oberseering 40, Hamburg D-22297, Federal Republic of Germany) were dispersed in 31 (liters) of water with a laboratory stirring unit. Subsequently the pH-value of the dispersion was set to 2 via slow addition of nitric acid. A grinding was not carried out. Examples 5 to 10 describe the production of boehmites via autocatalytic, hydrothermal crystallization with the embodiment seed crystal according to Example 1 as well as the comparative seed crystals according to the Examples 2 to 4. The following Examples 5 to 9 concern the production on laboratory scale. 100 g of finely precipitated aluminumhydroxide (commercial designation APYRAL 40CD, Nabaltec Co.) and 10 g of seed crystal (in relation to the dry weight) in a dispersion produced according to the Examples 1 to 4 were mixed with a diluted base with roughly 40 (g/l) free Na20 with a laboratory stirring unit to obtain a total volume of 1 I. Example 5 contains the embodiment type of seed crystal. The Examples 6, 7 and 9 contain the respective comparative seed crystals of the comparative Examples 2, 3 and 4. In Example 8, a non-ground boehmite of the type ApAOH180 according to the Examples 1 or 2 was applied as seed crystal. The respective dispersions were each transferred into a laboratory autoclave (4520 Bench Top Reactor, manufactured by Parr Instrument Company, 211 Fifty Third Street, Moline, Illinois, 61265-9984) heated to 145°C and kept at that temperature 14 during continuous stirring at 1125 rpm for 24 hours. After cooling down the reaction mixture, said mixture was filtered, washed and dried in a laboratory drying unit for 24 hours at 110°C. Example 10 describes the production of the embodiment boehmite in a production-scale autoclave. Example 10: In a 8 m3 stirring unit'autoclave 1 m3 of concentrated base was provided, containing 170 (g/l) of free Na20, and united with a dispersion consisting of 2800 l(liters) of water, 500 l(liters) of aqueous seed crystal dispersion containing 50 kg of seed crystal according to Example 1 and 500 kg of finely precipitated aluminumhydroxide (designation APYRAL 60 D, Nabaltec Co. Germany). The resulting mixture was heated to 145°C and kept at that temperature under continuous stirring at 900 rpm for 21 hours. After cooling down the reaction mixture, said mixture was filtered via a Larox press filtering device and washed. The thus obtained filter cake was dried. Table 5 shows in comparison the product parameters of the boehmites obtained via autocatalytic crystallization under application of embodiment seed crystals according to Example 5 as well as Example 10 as well as the comparative seed crystals according to the Examples 6 to 9. The embodiment Example 5 shows the results obtained in a laboratory scale experiment while Example 10 shows the results of production carried out in production-scale. Some examples of production-scale autoclaves, which may possibly be used in at least one possible embodiment, are available from Avure Autoclave Systems, Inc., 3721 Corporate Drive, Columbus, OH, 43231-7999, U.S.A. 15 Only the embodiment examples leads to a product, which has boehmitic crystal structure as well as a particle size with a D50 grain size distribution in the order of 200 nm while at the same time the BET-surface is less than 30 m2/g and the pore volume is low. The application of the comparative seed crystals according to the Examples 6, 7 as well as 9 leads to a product that also has a boehmitic structure and the desired order of magnitude of particle size but is characterized by a considerably larger surface. The application of a non-ground seed crystal according to Example 8 leads to a boehmite with sufficiently small BET-surface. However, said product has a considerably larger particle size than required and is therefore not applicable. The crystal phase was determined via XRD. The hydrothermally produced, embodiment product can on its own part be used as a seed crystal. Carried out synthesis with seed crystal dispersions with seed crystals from the embodiment hydrothermal synthesis of boehmites under identical reaction conditions led to results, which confirm the properties described in Table 5. 16 5 table 5 parameters of products of produced boehmites according to examples 5) - 10). example type of seed-crystal reactor BET-surfacem2/g pore volume cm3/g primary particle size (D50) nm* XRD-phase loss afterHT-treatment% Nr. 5 (embod.) ApAOH180 3h p H3 laboratory-AC 29 0,08 200 boehmite 16,8 Nr. 6 (comp.) ApAOH180_3h laboratory-AC 45 0,11 200 boehmite 16,7 Nr. 7 (comp.) ApAOH60_3h laboratory-AC 45 0,11 200 boehmite 16,6 Nr. 8 (comp.) ApAOH180 laboratory-AC 11 0,02 500-600 boehmite 16,8 Nr. 9 (comp.) Pural SB_pep laboratory-AC 78 0,19 300 boehmite 16,4 Nr.10(embod.) ApAOH180 3h p H3 productionaIAC 28 0,07 200 boehmite 16,9 * optically determined via SEM-picture ** determined via Cilas Lasergranulometer 1064 10 laboratory AC = laboratory autoclave, volume 21 productional AC = productional autoclave, volume 8m3 (embod.) = embodiment example; (comp.) = comparative example 17 In the following the application of the embodiment produced boehmite as a flame retardant in plastic compositions is described. Examples 11 to 13 show the application of the embodiment product as flame retardant in basic polymer compositions and the resulting advantages. Such plastic compositions are applied for example in the production of electrical cables as compound material for producing cable insulation as well as cable sheathings. Example 11: Table 6 summarizes the composition and the important characteristics of a plastic compound, based on an EVA-copolymer with a vinylacetate-content of 19 i weight%. The comparative compositions C1 and C2 contain as sole flame retardant finely crystallized aluminiumhydroxide with a specific surface of about 4 m2/g (designation APYRAL® 40CD, Nabaltec Co. Germany) as well as 12 m2/g (designation APYRAL 120E, Nabaltec Co. Germany) concerning the BET-surface. The composition C3 contains aside the aluminiumhydroxide additionally boehmite of the type AOH180 as described above. The composition C4 contains the embodiment boehmite from Example 10 in combination with aluminiumhydroxide. All compositions have a fraction of filler material of60weight%. The compositions were produced with a dispersing kneading device of the type LDUK 1,0 of the company "Werner und Pfleiderer". Sample bodies for the following experiments were cut from plates which were produced in a press of the type Schwabenthanpresse Polystat 300S by press melting. The mechanical examinations 18 according to DIN 53504 were carried out with a tensile test machine of the type Tiratest 2705. The melt flow index according to ASTM D 1238 was determined with a Melt Flow Tester 6942, the oxygen index according to ISO 4589 (ASTM D 2863) was determined with a device of the type FTA of the Stanton Redcroft company. The determination of the level of inflammability was carried out according to the ^standard UL 94 V (UL = Underwriters Laboratories; an industrial union for standardisation). A rectangular sample body with vertically arranged length was mounted upright and freely. The length/broadth/thickness was 125 mm/13 mm/3,2 mm. The flame of a Bunsen burner was applied to encompass for a duration of 10 seconds and a height of flame of 20 mm +- 2mm the lower, free end of the sample body. The length of time, in which the sample body kept burning after removal of the flame, was recorded. Then the sample body was again encompassed with the flame for 10 seconds as predescribed and the time in which the sample body kept burning after removal of the flame was recorded. The two periods of time of each sample were added and recorded. Five sample bodies were examined for each composition respectively. Compositions having in each of their samples a total burning time of equal to or less than 10 seconds and having a total burning time of all 5 samples of altogether 50 or less seconds and which produced during burning no flaming drops, were given the highest level of inflammability UL 94 V-0. Compositions in which the burning of each sample was more than 10 seconds but less than 30 seconds, and which showed a total burning time of all 5 samples of 250 seconds or less and equally produced no burning drops during burning, were given the level of inflammability of UL 94 V1. If the time of burning of a sample was longer and/or the production of flaming drops during examination could be observed, no level of inflammability could be given. 19 ■ table 6 composition C1 C2 C3 C4 EscoreneUL 00119 39,6 39,6 39,6 39,6 Dynasylan AMEO 0,4 0,4 0,4 0,4 aluminiumhydroxide 4m2/g surface 60 55 55 aluminiumhydroxide 12m2/g surface 60 AOH180 5 product from example 10 5 total 100 100 100 100 table 7 composition C1 C2 C3 C4 tensile strength (MPa) 13,2 14,4 14,1 14,9 elongation at break (%) 210 165 194 209 LOI (%02) 35 40 36,5 39 UL94 level of inflammability none V-1 none V-0 MFI(crrr7l0min); 21,6kg/190°C 5,1 0,9 4,3 3,7 BET (m2/g)of the filler or the fillercomposition 3,5 12 4,9 5,5 Escorene UL00119 is an EVA-copolymer of ExxonMobil. Dynasylan AMEO is an aminosilane of the Degussa AG. Tensile strength derived from determination of elongation under tension according to DIN 53504 Elongation at break derived from determination of elongation under tension according to DIN 53504 LOI Limiting oxygen index (oxygen index) according to ISO 4589 MFI Melt flow index (melt index) according to ASTM D 1238 20 When comparing the results depicted in Table 7 concerning the properties as a flame retardant in respect of LOI and UL94V it shows that only the boehmite containing composition C4 is able to obtain the highest level of inflammability UL94V-0. Application of an aluminumhydroxide with a higher specific surface according to composition C2 the LOI can be increased in comparison to composition C1, but only a. level of inflammability of UL94V-1 can be obtained. Combination with a boehmite according to the known process as shown in composition C3, one can increase the LOI slightly, but no relevant level of inflammability according to UL94V can be obtained. Application of the boehmite leads not only to the highest level of inflammability but also improves the mechanical properties. The composition C4 shows additionally a high melt flow index, which results in an improved processability of the melt, like for example the extrusion. Example 12: The Example 12 shows plastic compositions C5 and C6 with the product and a reduced fraction of flame retardant while keeping the LOI. In Table 8 composition C1 is given as a reference from Example 11. Additionally the properties of the compositions C5 and C6, having a reduced fraction of inorganic filler as a flame retardant in comparison to composition C1, are given. 21 table 8 composition C1 C5 C6 Escorene UL 00119 39,6 41,6 44,6 Dynasylan AMEO 0,4 0,4 0,4 aluminiumhydroxide 4m2/g surface 60 48 45 product from example 10 10 10 total 100 100 100 tensile strength (MPa) 13,2 14,8 14,7 elongation at break {%) 210 216 241 LOI (%02) 35,0 36,0 34,6 MFI(cmVlOmin); 21,6kg/190°C 5,1 2,0 3,6 BET(m2/g)of the filler or the fillercomposition 3,5 7,7 8,0 Composition C5 shows that in spite of reducing the fraction of flame retardant by 2 % an increased LOI can be obtained. Composition C6 shows that while decreasing the fraction of flame retardant by 5 % the LOI can be kept and at the same time, because of said reduced fraction and the presence of the boehmite, excellent tensile strength and elongation at break is obtained. 22 Example 13: The example shows the effect of the finely crystallized particles on the LOI in polyamide (PA6). Composition C7 contains the commercially crystalline boehmite ApAOH60 from comparative Example 2, while the composition C8 contains the boehmite according to Example 10. table 9 composition C7 C8 Ultramid 5B 70 70 APYRAL®AOH60 30 product from example 10 30 total 100 100 LOI (%02) 23,0 30,8 Utramid 5B is a polyamide 6 of BASF AG. By application of the embodiment boehmite a considerably higher LOI can be obtained. At least one possible embodiment of the present application concerns a method for the production of a finely-particulate boehmite with an average grain diameter within the area of 50 to 400 nm and a-BET-surface within the area of 10 to 40 m2/g by autocatalytic, hydrothermal crystallization. At least one possible embodiment of the 23 present application concerns furthermore the application of a finely crystalline boehmite as flame retardant in plastics. One feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a boehmite characterized by an average grain size diameter D50 in the range of 50 to 400 nm, a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 cm3/g. Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a method for the production of a seed crystal for the autocatalytic hydrothermal crystallization of boehmite comprising the steps of: a. producing an aqueous dispersion of an aluminummonohydrate source with boehmitic crystal structure; and b. grinding the dispersion characterized in that the pH-value is kept in a range of 2 to 4 during grinding. Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the pH-value is adjusted with an organic acid, preferably acetic acid. Still another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the dispersion in step a) shows a fraction of solid content of 5 to 50 weight%, preferably 10 to 25 weight% of aluminummonohydrate-source. A further feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that in step b) the temperature of the dispersion is kept in a range of 50 to 70°C. Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the 24 aluminummonohydrate source has an average grain size diameter D50 of 500 nm or more as well as a BET-surface of 20 m2/g or more. Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a method for production of a boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g via autocatalytic hydrothermal crystallization comprising the steps of: c. providing an aqueous basic dispersion containing a hydrate source and a crystalline seed, d. heating the dispersion in an autoclave to a temperature in the range 110 to 180°C until the hydrate source is essentially used up, and e. drying of the obtained product characterized in that the crystalline seed is produced according to one of the claims 3 to 7 and/or is the product of a previous cycle of this method. Still another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the solid concentration of crystalline seed is 0,5 to 50 %, preferably 1 to 20 % in relation to the hydrate source. A further feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the concentration of sodium hydroxide solution in the dispersion is 4 to 50 g/l, preferably 30 to 40 g/l in relation to free Na20. Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method, characterized in that the hydrate source has a grain size distribution D50 of 0,5 to 100 micrometer, preferably 0,5 to 10 micrometer and a concentration within the dispersion of 10 to 500 g/l, preferably 50 to 150 g/l. 25 Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in an application of the boehmite as a flame retardant in plastics especially in compositions for insulation or sheathings of electrical cables. 26 We Claim: 1. Boehmite characterized by an average grain size diameter D50 in the range of 50 to 400 nm, a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of0,05to0,5cm3/g. 2. Method for the production of a seed crystal for the autocatalytic hydrothermal crystallisation of boehmite comprising the steps of a. producing an aqueous dispersion of an aluminummonohydrate source with boehmitic crystal structure and b. grinding the dispersion characterized in that the pH-value is kept in a range of 2 to 4 during grinding. 3. Method according to claim 2 characterized in that the pH-value is adjusted with an organic acid, preferably acetic acid. 4. Method according to claim 2 or 3 characterized in that the dispersion in step a) shows a fraction of solid content of 5 to 50 weight%, preferably 10 to 25 weight% of aluminummonohydrate-source. 5. Method according to claims 2 to 4 characterized in that in step b) the temperature of the dispersion is kept in a range of 50 to 70°C. 6. Method according to one of the claims 2 to 5 characterized in that the aluminummonohydrate source has an average grain size diameter D50 of 500 nm or more as well as a BET-surface of 20 m2/g or more. 7. Method for production of a boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g via autocatalytic hydrothermal crystallisation comprising the steps of 27 a. providing an aqueous basic dispersion containing a hydrate source and a crystalline seed, b. heating the dispersion in an autoclave to a temperature in the range 110 to 180°C until the hydrate source is essentially used up, c. drying of the obtained product characterized in that the crystalline seed is produced according to one of the claims 3 to 7 and/or is the product of a previous cycle of this method. 8. Method according to claim 7 characterized in that the solid concentration of crystalline seed is 0,5 to 50 %, preferably 1 to 20 % in relation to the hydrate source. 9. Method according to claims 7 or 8 characterized in that the concentration of sodium hydroxide solution in the dispersion is 4 to 50 g/l, preferably 30 to 40 g/l in relation to free Na20. 10. Method according to one of the claims 7 to 9 characterized in that the hydrate source has a grain size distribution D50 of 0,5 to 100 micrometer, preferably 0,5 to 10 micrometer and a concentration within the dispersion of 10 to 500 g/l, preferably 50 to 150 g/l. 11. Application of the boehmite according to claim 1 as a flame retardant in plastics especially in compositions for insulation or sheathings of electrical cables. 28 Abstract Method for the production of a finely crystalline boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 m3/g via autocatalytic, hydrothermal crystallisation and method for production of a crystalline seed for crystallisation via grinding of an aluminummonohydrate source at a pH-value in the range of 2 to 4 and application of boehmite as a flame retardant in plastic compositions.

Full Text

FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
Provisional /Complete specification
[See Section 10 and rule 13]

1 Title of the Invention.
"Method for the production of a finely crystalline boehmite ar boehmite as flame retardant in plastics" id application of said
2 Applicant (s)
Applicant Nabaltec AG
Nationality GERMANY
Address Alustr. 50-52, 92421 Schwandorf, Germany.
The following specification particularly describes the invention and the manner in which it is to be performed.
1

METHOD FOR THE PRODUCTION OF A FINELY CRYSTALLINE BOEHMITE AND APPLICATION OF SAID BOEHMITE AS FLAME RETARDANT IN PLASTICS
BACKGROUND
1. Technical Field:
This application relates to a method for the production of a finely crystalline boehmite and application of said boehmite as flame retardant in plastics.
2. Background Information:
From US 4,117,105 the conversion of aluminumtrihydrate to well dispersable boehmite is known. According to one method, aluminumtrihydrate with a BET-surface of 0,2 to 15 m2/g is calcined at temperatures between 200 up to 800°C for 2 to 17 hours, until the BET-surface has risen to 250 to 800 m2/g. The Brunauer-Emmett-Teller (BET) method is a method of measuring the amount of gas absorbed on a solid surface. Then a slurry of the calcined alumina is rehydrated at a temperature of 140 to 200DC for 0,5 to 6 hours in an autoclave.
A flame retardant plastic composition and a method for producing a filler material is known from German Patent No. 19812279 C1. The plastic composition consists of 55 to 75 % boehmite in an orthorhombic crystal structure, wherein, depending on temperature control, the BET-surface varies between 14,75 and 17,25 m2/g. As filler material boehmite with a grain diameter of 0,5 up to 3 micrometer is applied.
From German Patent No. 69231902 T2 a method for the growth of crystals, especially crystals consisting of metal oxides, at increased speed is known. In said method BET-surfaces in a range of 40 m2/g at a crystal size of roughly 50 nm are obtained. Within said method a feed solution with a pH-value of 3 to 11 is provided for precipitation on a seed crystal, which comprises a metal oxide species, which is
2

sufficiently insoluble in the aqueous medium, in order to provide a solid center of growth. The treatment is then carried out under hydrothermal conditions, wherein feed material is added until the end of crystal growth.
In Japanese Patent No. 63265810 A a method is described, in which smooth ct-Al203-spheres are obtained from an aluminumhydrate, wherein aluminumhydrate is ground in wet condition at a pH-value between 1 and 4. Said a-AI203 is obtained subsequently by calcination at 1350 to 1500°C.
From the production of the ion conductor beta-alumina, it is known from German Patent No. 3617115 A1 to mix boehmite with water and to adjust the pH-value of the mixture with acetic acid to a pH-value of 4. The mixture is then ground and sodium oxide and a spinel-stabilizator are mixed into the ground mixture in aqueous solution whereafter the solution is peptised, e.g. by acidifying anew to a pH of 4 with acetic acid and the following, production of a gel at raised temperatures (80°C for 20 minutes). The product can preferably be formed into a self-supporting commodity, consisting of beta-alumina, by isostatic pressing.
A method for the production of quasi-crystalline boehmite from a boehmite-precursor by application of seed crystals in hydrothermal treatment is known from German Patent No. 60015345 T2. Also ground boehmite crystals can be applied as crystals, wherein the hydrothermal reaction is carried out at pH-values equal or smaller than 7. Furthermore the production of microcrystalline boehmite and ceramic bodies is described in German Patent No. 3879584, wherein a precursor of boehmite and boehmite seed crystals are applied under hydrothermal conditions at pH-values of 8 or higher and temperatures of above 130°C. A method for the production of finest-particulate seed crystals is known from United States Statutory Invention Registration H189, published January 6, 1987. With said seed material alpha alumina is obtained by
3

applying the seed material in a boehmite-gel and transformation at relatively moderate temperatures into finely crystalline alpha alumina. Said material is applied within electrical industrial production or as abrasive.
For the application in flame retardants in plastic compositions a finely crystalline boehmite is required, having a low surface and a low pore volume. The flame retardant should show good and easy miscibility with said plastic compounds while having a high fraction at the total composition and also a high level of inflammability or non-flammability should be obtained. Furthermore the properties of mechanical strength like tensile strength and elongation at break should be on a high level.
OBJECT OR OBJECTS
An object of at least one possible embodiment of the present application is to provide a method for production of fine crystalline boehmite having a low surface and a low pore volume, which is easily miscible into plastic compounds at a high fraction of the total composition and provides a high level of inflammability or non-flammability while enabling excellent properties of mechanical strength.
SUMMARY
At least one possible embodiment of the present application is a method for production of fine crystalline boehmite having a low surface and a low pore volume, which is easily miscible into plastic compounds at a high fraction of the total composition and provides a high level of inflammability while enabling excellent properties of mechanical strength.
According to at least one possible embodiment of the present application, a fine-crystalline boehmite is provided having an average grain diameter of D50 (D50 = the
4

median diameter) in the range of 50 to 400 nm in one embodiment, in the range of 100 to 300 nm in another embodiment, or in the range of 150 to 250 nm in yet another embodiment. Furthermore the micro-particulate boehmite has a BET-surface in the range of 10 to 40 m2/g, more preferably 15 to 35 m2/g, most preferably 15 to 30 m2/g. In a further embodiment the boehmite has a pore volume in the range of 0,05 to 0,5 cm3/g, especially preferred 0,1 to 0,4 cm3/g.
According to at least one possible embodiment of the present application, the predescribed fine-crystalline boehmite with low surface is produced from a hydrate source by the method of autocatalytic, hydrothermal crystallization. Autocatalytic generally describes a reaction in which the reaction product itself is a catalyst for the reaction. Hydrothermal generally describes a technique for crystallization of substances from higher temperatures at higher pressures. The method will be described in the following. According to the embodiment hereof, it is essential or highly desirable during implementation of the method to apply a special type of seed crystal. The properties of the type of seed crystal as well as a method for its production are explained in detail in the following.
For the production of the embodiment of the seed crystal an aluminummonohydrate source is used. The aluminummonohydrate source (AIO(OH)) is of boehmitic crystal structure and has an appropriate particle size with a D50 grain size of about 500 nm or larger as well as a BET-surface of 20 m2/g or larger. Such aluminummonohydrate sources can be obtained in trade for example under the commercial designation APYRAL produced by Nabaltec Co. Germany, located at Nabaltec AG, Alustrasse 50-52, 92421 Schwandorf, Federal Republic of Germany.
Subsequently an aqueous dispersion is produced from the aluminummonohydrate source and said dispersion is ground, preferably in a ball-mill. A
5

ball mill is generally a type of mill that uses either balls or pebbles, usually ceramic, to reduce a wet or dry material down to specified size by grinding the material with the balls or pebbles.
Surprisingly it turned out that during grinding of the aluminummonohydrate source in an aqueous suspension at a pH-value in the range of 2 to 4 in one embodiment, in the range of 2.5 to 4.5 in another embodiment, or even at a pH-value of 3 in yet another embodiment, the BET-surface and the pore volume increase only slightly when compared to grinding in neutral or slightly basic dispersion. Organic acids, especially acetic acid, turned out to be especially appropriate. It may be assumed that organic acids promote the creation of smooth fractured surfaces during tribochemical reaction, which takes place during grinding between the grinding gear, the dispersion liquid and the fracturing surface of the boehmite. Tribochemistry is generally defined as a field of chemistry that focuses on chemical reactions occurring on the surface of an object or substance.
Acetic acid showed in a sequence of experiments an optimal or desirable combination of acid strength, stability, solubility of its salts and miscibility with water. The stronger acids like formic acid or oxalic acid, tended to decompose at higher reaction temperature while organic acids with longer carbon chains, which are less miscible with water, like pentane- and hexane-acid showed a considerably decreased velocity of reaction and produced salts which are hardly soluble. With the application of acetic acid while keeping the reaction temperature between 50°C and 70°C a quick transformation and grinding could always be carried out, without the acetic acid decomposing or producing insoluble salts to an undesirable or unacceptable degree.
6

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the evolution of the BET-surface in relation to the duration of grinding for 3 crystalline precursor boehmites;
Figure 2 shows a comparison of the evolution of BET-surface in relation to the duration of grinding for a time span of 180 minutes, wherein a dispersion having a pH-value of 9 and second dispersion having a pH-value of 4 are compared; and
Figure 3 shows the results of the determination of the evolution of pore volumes
during the experiments of Figure 2.
i ■
DESCRIPTION OF EMBODIMENT OR EMBODIMENTS
Figure 1 displays the evolution of the BET-surface in relation to the duration of grinding for 3 crystalline precursor boehmites as described in table 1. The results of a grinding according to a known process in neutral aqueous dispersion are shown. The concentration of solids was 10 % in relation to the boehmitic aluminummonohydrate-source. Table 1 shows the average grain size as well as BET-surface of the applied precursor substances prior to grinding. The determination of the BET-surface was carried out according to DIN 66131; likewise the following BET-values (DIN = German Industrial Standard).
table 1

D50 (nm) BET (m'/g) commercial designation
3000 10 AOH 103
1300 10 AOH 104
600 20 AOH 180
7

As can be seen from Figure 1, the BET-surface increases for all 3 precursor boehmites as could or should be expected with increasing duration of grinding and the respective decrease of the size of the crystals. The course of evolution of the BET-surface in relation to the duration of grinding at a maximum duration of grinding of 3 hours (180 minutes) is demonstrated. The dispersion of the precursor-boehmites has a pH-valueof 9.
Figure 2 shows a comparison of the evolution of BET-surface in relation to the duration of grinding for a time span of 180 minutes, wherein a dispersion having a pH-value of 9 and second dispersion having a pH-value of 4 are compared. It can be seen from this figure that the increase of BET-surface is significantly less for the acidic dispersion. In both comparative experiments boehmite of the type AOH 180 according to Table 1 was applied.
Figure 3 shows the results of the determination of the evolution of pore volumes during the experiments of Figure 2. It is obvious that the pore volume in the acidic dispersion increases during grinding little or surprisingly little, while the pore volume of the commonly prepared dispersion increases considerably. The determination of the pore volume was carried out according DIN 66134 via nitrogen-sorption at 77 K with 99,99% pure, dry nitrogen; all following pore volumes likewise. The pore volume was determined from the nitrogen adsorption or nitrogen desorption branch respectively of the isotherms according to Gurwitsch.
Further experiments with varied concentration of solids of boehmitic aluminummonohydrate source confirmed the situation depicted in Figure 3. With a solid fraction, concerning the boehmitic aluminummonohydrate source, in the range of 5 to 50% in one possible embodiment or in the range of 10 to 25% in another possible
8

embodiment, the described change of pore volume in acidic dispersion could always or usually be found.
Furthermore the temperature of the dispersion was kept in a range of 50 to 70°C in one possible embodiment or at a temperature of 60°C in another possible embodiment, during grinding. The cooling of the dispersion can be carried out with known cooling-facilities. If the heat generated during a grinding reaction is removed via cooling and the temperature is kept between 50 and 70°C, the amount of water evaporized during grinding is negligibly small. If temperature peaks of 80°C or more occur during grinding, for example, the water content may be controlled at intervals of 10 minutes and water may have to be refilled as needed. With a grinding reaction at 60°C a dispersion can often be ground for several hours without the refilling of water becoming necessary. Especially when applying organic acids the amount of evaporized acid is generally so little, that ignitable mixtures of acids and air are generally securely prevented.
The obtained product is applied as seed crystal for hydrothermal synthesis of boehmite in the following. When the grinding has reached completion the dispersion can be applied directly as a dispersion of seed crystals.
In the following, the method for the production of the fine-crystalline boehmite with low surface via autocatalytic hydrothermal crystallization with application of the previously described boehmite-seed crystal is explained.
For carrying out the autocatalytic hydrothermal crystallization, an alkaline aqueous dispersion is provided, comprising an applicable hydrate source such as (AI(OH)3) as well as the previously described type of embodiment seed crystal. The hydrate source which is produced from a dispersion, has a grain size distribution D50 of 0,5 to 100 micrometer in at least one possible embodiment, 0,5 to 10 micrometer in
9

another possible embodiment, or 0,5 to 2 micrometer in yet another embodiment. The concentration of the hydrate source in the dispersion is normally adjusted to 10 to 500 (g/l) in at least one possible embodiment, 50 to 150 (g/l) in another possible embodiment, or 90 to 110 (g/l) in yet another possible embodiment. The concentration of the sodium hydroxide solution within the dispersion can be 4 to 50 in one possible embodiment, 30 to 40 (g/l) in another embodiment in relation to free Na20. The concentration of solids concerning the seed crystal is generally adequately set to 0,5 to 50% in one possible embodiment, 1 to 20% in another possible embodiment, or even 5 to 15% in yet another possible embodiment, each in relation to the hydrate source.
The autocatalytic hydrothermal crystallization of the previously described dispersion is carried out in an adequate autoclave. The reaction temperature is within a range of 110 to 180°C in at least one possible embodiment, within a range of 120 to 150°C in another possible embodiment, or even within a range of 125 to 135°C in yet another possible embodiment. The reaction time is between 4 up to 24 hours depending on the rate of consumption of the hydrate source.
In one possible embodiment, the method can be carried out in a chemiclave, which is a specific type of autoclave. A type of chemiclave is manufactured by Alpha Multiservices, Inc. 706 Brook Hollow Dr., Conroe, TX 77385-9109, U.S.A.
The production of the embodiment type of seed crystal as well as its advantages compared to the known process as well as the production of the embodiment boehmite via autocatalytic, hydrothermal crystallization while applying the previously introduced type of seed crystal, will be explained further in the following examples.
10

Example 1:
Production of an embodiment type of seed crystal 300 g of a finely crystallized aluminummonohydrate with a specific surface of 20 m2/g and an average grain diameter D50 of 500 up to 600 nm (obtainable by the commercial designation APYRAL AOH 180, fabricated by Nabaltec Co. Germany) were dispersed in 3 l(liters) water using a laboratory stirring unit. Said dispersion was adjusted to a pH-value of about 3 via the addition of acetic acid and was ground in a laboratory ball-mill. A ball-mill of the type (PML HA/) of the company Drais, located at 40 Whitney Road, Mahwah, New Jersey, 07430, was applied. As grinding media milling balls of 300 to 400 micrometer diameter made from yttria stabilized zirconia were applied. The dispersion was ground for up to 3 hours. (Yttria = yttrium oxide, Y203) The temperature was kept at 60°C.
Samples were taken from the initial substance as well as after 30 min., 60 min. and 180 min. of grinding. Table 2 shows the important parameters of the resulting products.
table 2

duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size(D50)nm*
initial ApAOH180 20 0,03 500-600
30 min ApAOH180_0,5h_pH3 33 0,05 400-500
60 min ApAOH180Jh_pH3 42 0,07 300-400
180 min ApAOH180_3h_pH3 50 0,08 200-300
* optically determined via SEM-picture (SEM = scanning electron microscope)
11

Example 2: -Comparative Example-
300 g of a finely crystallized aluminummonohydrate with a specific surface of 20 m2/g as in Example 1 were dispersed in water with a laboratory stirring unit. Said dispersion was ground in a laboratory ball-mill at a pH-value of about 9. As grinding media milling balls of 300 up to 400 micrometer diameter were applied. The dispersion was ground for up to 3 hours.
Samples were taken of the initial substance as well as after 30 min., 60 min. and 180 min. of grinding. Table 3 shows the important parameters of the resulting products, table 3

duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size(D50)in nm*
initial ApAOH180 20 0,03 500-600
30 min ApAOH180_0,5h 40 0,10 400-500
60 min ApAOH180_1h 54 0,14 300-400
180 min ApAOH180_3h 83 0,23 200-300
* optically determined via SEM-picture
Example 3: -Comparative Example-
300 g of a finely crystallized alumniummonohydrate with a specific surface of 6 m2/g (obtainable by the commercial designation APYRAL AOH 60 Nabaltec Co. Germany) were ground with a laboratory ball-mill as in Example 1 but at a pH-value of 9. As grinding media milling balls of 300 up to 400 micrometer diameter of yttria stabilized zirconia were applied. The dispersion was ground for up to 3 hours.
12

Samples were taken of the initial substance as well as after 30 min, 60 min and 180 min of grinding. Table 4 shows the important parameters of the resulting products, table 4

duration of grinding commercial designation BET-surfacem2/g pore volume cm3/g particle size (D50)nm*
initial ApAOH60 6 0,01 1000
60 min ApAOH60_1h 44 0,09 600-700
120 min ApAOH60_2h 65 0,14 400-500
180 min ApAOH60_3h 78 0,17 200-300
* optically determined via SEM-picture
The comparison of the Examples 1 to 3 shows directly the advantages of the embodiment type of seed crystal as well as of its method of production. The embodiment Example 1 shows that starting from a commercially obtainable boehmite with a grain size diameter D50 of 500 to 600 nm and a BET-surface of 20 m2/g a seed crystal can be obtained with a targeted grain size of 200 up to 300 nm while at the same time the BET-surface as well as the pore volume increase only moderately. In direct comparison with comparative Example 2, starting with identical boehmite as precursor, according to the known process a considerably larger BET-surface as well as considerably larger pore volumes are obtained when the targeted grain size is reached.
Even if a boehmite with a decreased BET-surface is used as a precursor, the production of the seed crystal according to the known process obtains a considerably larger BET-surface when reaching the targeted grain size of 200 up to 300 nm.
13

Example 4:
-Comparative Example-
Preparation of a seed crystal dispersion on the basis of a commercial pseudo boehmite. 100 g of amorphous aluminummonohydrate with a specific surface of 261 m2/g and a particle size D50 of 37 micrometer as well as a pore volume of 0,37 cm2/g (obtainable by the commercial designation Plural SB, fabricated by Condea Chemie Co. Germany, located at Oberseering 40, Hamburg D-22297, Federal Republic of Germany) were dispersed in 31 (liters) of water with a laboratory stirring unit. Subsequently the pH-value of the dispersion was set to 2 via slow addition of nitric acid. A grinding was not carried out.
Examples 5 to 10 describe the production of boehmites via autocatalytic, hydrothermal crystallization with the embodiment seed crystal according to Example 1 as well as the comparative seed crystals according to the Examples 2 to 4.
The following Examples 5 to 9 concern the production on laboratory scale. 100 g of finely precipitated aluminumhydroxide (commercial designation APYRAL 40CD, Nabaltec Co.) and 10 g of seed crystal (in relation to the dry weight) in a dispersion produced according to the Examples 1 to 4 were mixed with a diluted base with roughly 40 (g/l) free Na20 with a laboratory stirring unit to obtain a total volume of 1 I. Example 5 contains the embodiment type of seed crystal. The Examples 6, 7 and 9 contain the respective comparative seed crystals of the comparative Examples 2, 3 and 4. In Example 8, a non-ground boehmite of the type ApAOH180 according to the Examples 1 or 2 was applied as seed crystal.
The respective dispersions were each transferred into a laboratory autoclave (4520 Bench Top Reactor, manufactured by Parr Instrument Company, 211 Fifty Third Street, Moline, Illinois, 61265-9984) heated to 145°C and kept at that temperature
14

during continuous stirring at 1125 rpm for 24 hours. After cooling down the reaction mixture, said mixture was filtered, washed and dried in a laboratory drying unit for 24 hours at 110°C.
Example 10 describes the production of the embodiment boehmite in a production-scale autoclave.
Example 10:
In a 8 m3 stirring unit'autoclave 1 m3 of concentrated base was provided, containing 170 (g/l) of free Na20, and united with a dispersion consisting of 2800 l(liters) of water, 500 l(liters) of aqueous seed crystal dispersion containing 50 kg of seed crystal according to Example 1 and 500 kg of finely precipitated aluminumhydroxide (designation APYRAL 60 D, Nabaltec Co. Germany). The resulting mixture was heated to 145°C and kept at that temperature under continuous stirring at 900 rpm for 21 hours.
After cooling down the reaction mixture, said mixture was filtered via a Larox press filtering device and washed. The thus obtained filter cake was dried.
Table 5 shows in comparison the product parameters of the boehmites obtained via autocatalytic crystallization under application of embodiment seed crystals according to Example 5 as well as Example 10 as well as the comparative seed crystals according to the Examples 6 to 9. The embodiment Example 5 shows the results obtained in a laboratory scale experiment while Example 10 shows the results of production carried out in production-scale.
Some examples of production-scale autoclaves, which may possibly be used in at least one possible embodiment, are available from Avure Autoclave Systems, Inc., 3721 Corporate Drive, Columbus, OH, 43231-7999, U.S.A.
15

Only the embodiment examples leads to a product, which has boehmitic crystal structure as well as a particle size with a D50 grain size distribution in the order of 200 nm while at the same time the BET-surface is less than 30 m2/g and the pore volume is low.
The application of the comparative seed crystals according to the Examples 6, 7 as well as 9 leads to a product that also has a boehmitic structure and the desired order of magnitude of particle size but is characterized by a considerably larger surface. The application of a non-ground seed crystal according to Example 8 leads to a boehmite with sufficiently small BET-surface. However, said product has a considerably larger particle size than required and is therefore not applicable. The crystal phase was determined via XRD.
The hydrothermally produced, embodiment product can on its own part be used as a seed crystal. Carried out synthesis with seed crystal dispersions with seed crystals from the embodiment hydrothermal synthesis of boehmites under identical reaction conditions led to results, which confirm the properties described in Table 5.
16

5
table 5
parameters of products of produced boehmites according to examples 5) - 10).

example type of seed-crystal reactor BET-surfacem2/g pore volume cm3/g primary particle size (D50) nm* XRD-phase loss afterHT-treatment%
Nr. 5 (embod.) ApAOH180 3h p H3 laboratory-AC 29 0,08 200 boehmite 16,8
Nr. 6 (comp.) ApAOH180_3h laboratory-AC 45 0,11 200 boehmite 16,7
Nr. 7 (comp.) ApAOH60_3h laboratory-AC 45 0,11 200 boehmite 16,6
Nr. 8 (comp.) ApAOH180 laboratory-AC 11 0,02 500-600 boehmite 16,8
Nr. 9 (comp.) Pural SB_pep laboratory-AC 78 0,19 300 boehmite 16,4
Nr.10(embod.) ApAOH180 3h p H3 productionaIAC 28 0,07 200 boehmite 16,9
* optically determined via SEM-picture ** determined via Cilas Lasergranulometer 1064 10 laboratory AC = laboratory autoclave, volume 21
productional AC = productional autoclave, volume 8m3
(embod.) = embodiment example; (comp.) = comparative example
17

In the following the application of the embodiment produced boehmite as a flame retardant in plastic compositions is described.
Examples 11 to 13 show the application of the embodiment product as flame retardant in basic polymer compositions and the resulting advantages. Such plastic compositions are applied for example in the production of electrical cables as compound material for producing cable insulation as well as cable sheathings.
Example 11:
Table 6 summarizes the composition and the important characteristics of a
plastic compound, based on an EVA-copolymer with a vinylacetate-content of 19
i weight%. The comparative compositions C1 and C2 contain as sole flame retardant
finely crystallized aluminiumhydroxide with a specific surface of about 4 m2/g
(designation APYRAL® 40CD, Nabaltec Co. Germany) as well as 12 m2/g (designation
APYRAL 120E, Nabaltec Co. Germany) concerning the BET-surface. The composition
C3 contains aside the aluminiumhydroxide additionally boehmite of the type AOH180 as
described above.
The composition C4 contains the embodiment boehmite from Example 10 in combination with aluminiumhydroxide. All compositions have a fraction of filler material of60weight%.
The compositions were produced with a dispersing kneading device of the type LDUK 1,0 of the company "Werner und Pfleiderer". Sample bodies for the following experiments were cut from plates which were produced in a press of the type Schwabenthanpresse Polystat 300S by press melting. The mechanical examinations
18

according to DIN 53504 were carried out with a tensile test machine of the type Tiratest 2705. The melt flow index according to ASTM D 1238 was determined with a Melt Flow Tester 6942, the oxygen index according to ISO 4589 (ASTM D 2863) was determined with a device of the type FTA of the Stanton Redcroft company.
The determination of the level of inflammability was carried out according to the ^standard UL 94 V (UL = Underwriters Laboratories; an industrial union for standardisation). A rectangular sample body with vertically arranged length was mounted upright and freely. The length/broadth/thickness was 125 mm/13 mm/3,2 mm. The flame of a Bunsen burner was applied to encompass for a duration of 10 seconds and a height of flame of 20 mm +- 2mm the lower, free end of the sample body. The length of time, in which the sample body kept burning after removal of the flame, was recorded. Then the sample body was again encompassed with the flame for 10 seconds as predescribed and the time in which the sample body kept burning after removal of the flame was recorded. The two periods of time of each sample were added and recorded. Five sample bodies were examined for each composition respectively. Compositions having in each of their samples a total burning time of equal to or less than 10 seconds and having a total burning time of all 5 samples of altogether 50 or less seconds and which produced during burning no flaming drops, were given the highest level of inflammability UL 94 V-0. Compositions in which the burning of each sample was more than 10 seconds but less than 30 seconds, and which showed a total burning time of all 5 samples of 250 seconds or less and equally produced no burning drops during burning, were given the level of inflammability of UL 94 V1. If the time of burning of a sample was longer and/or the production of flaming drops during examination could be observed, no level of inflammability could be given.
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■ table 6

composition C1 C2 C3 C4
EscoreneUL 00119 39,6 39,6 39,6 39,6
Dynasylan AMEO 0,4 0,4 0,4 0,4
aluminiumhydroxide 4m2/g surface 60 55 55
aluminiumhydroxide 12m2/g surface 60
AOH180 5
product from example 10 5
total 100 100 100 100
table 7

composition C1 C2 C3 C4
tensile strength (MPa) 13,2 14,4 14,1 14,9
elongation at break (%) 210 165 194 209
LOI (%02) 35 40 36,5 39
UL94 level of inflammability none V-1 none V-0
MFI(crrr7l0min); 21,6kg/190°C 5,1 0,9 4,3 3,7
BET (m2/g)of the filler or the fillercomposition 3,5 12 4,9 5,5
Escorene UL00119 is an EVA-copolymer of ExxonMobil.
Dynasylan AMEO is an aminosilane of the Degussa AG.
Tensile strength derived from determination of elongation under tension
according to DIN 53504
Elongation at break derived from determination of elongation under tension
according to DIN 53504
LOI Limiting oxygen index (oxygen index) according to ISO 4589
MFI Melt flow index (melt index) according to ASTM D 1238
20

When comparing the results depicted in Table 7 concerning the properties as a flame retardant in respect of LOI and UL94V it shows that only the boehmite containing composition C4 is able to obtain the highest level of inflammability UL94V-0.
Application of an aluminumhydroxide with a higher specific surface according to composition C2 the LOI can be increased in comparison to composition C1, but only a. level of inflammability of UL94V-1 can be obtained. Combination with a boehmite according to the known process as shown in composition C3, one can increase the LOI slightly, but no relevant level of inflammability according to UL94V can be obtained. Application of the boehmite leads not only to the highest level of inflammability but also improves the mechanical properties. The composition C4 shows additionally a high melt flow index, which results in an improved processability of the melt, like for example the extrusion.
Example 12:
The Example 12 shows plastic compositions C5 and C6 with the product and a reduced fraction of flame retardant while keeping the LOI.
In Table 8 composition C1 is given as a reference from Example 11. Additionally the properties of the compositions C5 and C6, having a reduced fraction of inorganic filler as a flame retardant in comparison to composition C1, are given.
21

table 8

composition C1 C5 C6
Escorene UL 00119 39,6 41,6 44,6
Dynasylan AMEO 0,4 0,4 0,4
aluminiumhydroxide 4m2/g surface 60 48 45
product from example 10 10 10
total 100 100 100
tensile strength (MPa) 13,2 14,8 14,7
elongation at break {%) 210 216 241
LOI (%02) 35,0 36,0 34,6
MFI(cmVlOmin); 21,6kg/190°C 5,1 2,0 3,6
BET(m2/g)of the filler or the fillercomposition 3,5 7,7 8,0
Composition C5 shows that in spite of reducing the fraction of flame retardant by 2 % an increased LOI can be obtained. Composition C6 shows that while decreasing the fraction of flame retardant by 5 % the LOI can be kept and at the same time, because of said reduced fraction and the presence of the boehmite, excellent tensile strength and elongation at break is obtained.
22

Example 13:
The example shows the effect of the finely crystallized particles on the LOI in polyamide (PA6).
Composition C7 contains the commercially crystalline boehmite ApAOH60 from comparative Example 2, while the composition C8 contains the boehmite according to Example 10.
table 9

composition C7 C8
Ultramid 5B 70 70
APYRAL®AOH60 30
product from example 10 30
total 100 100
LOI (%02) 23,0 30,8
Utramid 5B is a polyamide 6 of BASF AG.
By application of the embodiment boehmite a considerably higher LOI can be obtained.
At least one possible embodiment of the present application concerns a method for the production of a finely-particulate boehmite with an average grain diameter within the area of 50 to 400 nm and a-BET-surface within the area of 10 to 40 m2/g by autocatalytic, hydrothermal crystallization. At least one possible embodiment of the
23

present application concerns furthermore the application of a finely crystalline boehmite as flame retardant in plastics.
One feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a boehmite characterized by an average grain size diameter D50 in the range of 50 to 400 nm, a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 cm3/g.
Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a method for the production of a seed crystal for the autocatalytic hydrothermal crystallization of boehmite comprising the steps of: a. producing an aqueous dispersion of an aluminummonohydrate source with boehmitic crystal structure; and b. grinding the dispersion characterized in that the pH-value is kept in a range of 2 to 4 during grinding.
Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the pH-value is adjusted with an organic acid, preferably acetic acid.
Still another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the dispersion in step a) shows a fraction of solid content of 5 to 50 weight%, preferably 10 to 25 weight% of aluminummonohydrate-source.
A further feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that in step b) the temperature of the dispersion is kept in a range of 50 to 70°C.
Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the
24

aluminummonohydrate source has an average grain size diameter D50 of 500 nm or more as well as a BET-surface of 20 m2/g or more.
Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in a method for production of a boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g via autocatalytic hydrothermal crystallization comprising the steps of: c. providing an aqueous basic dispersion containing a hydrate source and a crystalline seed, d. heating the dispersion in an autoclave to a temperature in the range 110 to 180°C until the hydrate source is essentially used up, and e. drying of the obtained product characterized in that the crystalline seed is produced according to one of the claims 3 to 7 and/or is the product of a previous cycle of this method.
Still another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the solid concentration of crystalline seed is 0,5 to 50 %, preferably 1 to 20 % in relation to the hydrate source.
A further feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method characterized in that the concentration of sodium hydroxide solution in the dispersion is 4 to 50 g/l, preferably 30 to 40 g/l in relation to free Na20.
Another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in the method, characterized in that the hydrate source has a grain size distribution D50 of 0,5 to 100 micrometer, preferably 0,5 to 10 micrometer and a concentration within the dispersion of 10 to 500 g/l, preferably 50 to 150 g/l.
25

Yet another feature or aspect of an embodiment is believed at the time of the filing of this patent application to possibly reside broadly in an application of the boehmite as a flame retardant in plastics especially in compositions for insulation or sheathings of electrical cables.
26

We Claim:
1. Boehmite characterized by an average grain size diameter D50 in the range of 50 to 400 nm, a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of0,05to0,5cm3/g.
2. Method for the production of a seed crystal for the autocatalytic hydrothermal crystallisation of boehmite comprising the steps of
a. producing an aqueous dispersion of an aluminummonohydrate source with
boehmitic crystal structure and
b. grinding the dispersion characterized in that the pH-value is kept in a range of
2 to 4 during grinding.
3. Method according to claim 2 characterized in that the pH-value is adjusted with an organic acid, preferably acetic acid.
4. Method according to claim 2 or 3 characterized in that the dispersion in step a) shows a fraction of solid content of 5 to 50 weight%, preferably 10 to 25 weight% of aluminummonohydrate-source.
5. Method according to claims 2 to 4 characterized in that in step b) the temperature of the dispersion is kept in a range of 50 to 70°C.
6. Method according to one of the claims 2 to 5 characterized in that the aluminummonohydrate source has an average grain size diameter D50 of 500 nm or more as well as a BET-surface of 20 m2/g or more.
7. Method for production of a boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g via autocatalytic hydrothermal crystallisation comprising the steps of
27

a. providing an aqueous basic dispersion containing a hydrate source and a
crystalline seed,
b. heating the dispersion in an autoclave to a temperature in the range 110 to
180°C until the hydrate source is essentially used up,
c. drying of the obtained product characterized in that the crystalline seed is
produced according to one of the claims 3 to 7 and/or is the product of a
previous cycle of this method.
8. Method according to claim 7 characterized in that the solid concentration of crystalline seed is 0,5 to 50 %, preferably 1 to 20 % in relation to the hydrate source.
9. Method according to claims 7 or 8 characterized in that the concentration of sodium hydroxide solution in the dispersion is 4 to 50 g/l, preferably 30 to 40 g/l in relation to free Na20.
10. Method according to one of the claims 7 to 9 characterized in that the hydrate source has a grain size distribution D50 of 0,5 to 100 micrometer, preferably 0,5 to 10 micrometer and a concentration within the dispersion of 10 to 500 g/l, preferably 50 to 150 g/l.
11. Application of the boehmite according to claim 1 as a flame retardant in plastics especially in compositions for insulation or sheathings of electrical cables.

28

Abstract
Method for the production of a finely crystalline boehmite with an average grain size diameter D50 in the range of 50 to 400 nm and a BET-surface in the range of 10 to 40 m2/g and a pore volume in the range of 0,05 to 0,5 m3/g via autocatalytic, hydrothermal crystallisation and method for production of a crystalline seed for crystallisation via grinding of an aluminummonohydrate source at a pH-value in the range of 2 to 4 and application of boehmite as a flame retardant in plastic compositions.

Documents:

479-MUM-2007-ABSTRACT(14-3-2007).pdf

479-MUM-2007-ABSTRACT(GRANTED)-(19-12-2011).pdf

479-mum-2007-abstract.doc

479-mum-2007-abstract.pdf

479-MUM-2007-CANCELLED PAGES(6-4-2011).pdf

479-MUM-2007-CLAIMS(14-3-2007).pdf

479-MUM-2007-CLAIMS(AMENDED)-(14-5-2010).pdf

479-MUM-2007-CLAIMS(AMENDED)-(14-5-2011).pdf

479-MUM-2007-CLAIMS(AMENDED)-(28-4-2010).pdf

479-MUM-2007-CLAIMS(AMENDED)-(6-4-2011).pdf

479-MUM-2007-CLAIMS(GRANTED)-(19-12-2011).pdf

479-mum-2007-claims.doc

479-mum-2007-claims.pdf

479-MUM-2007-CORRESPONDENCE(14-5-2010).pdf

479-MUM-2007-CORRESPONDENCE(21-5-2007).pdf

479-MUM-2007-CORRESPONDENCE(24-10-2011).pdf

479-MUM-2007-CORRESPONDENCE(4-3-2011).pdf

479-MUM-2007-CORRESPONDENCE(6-4-2011).pdf

479-MUM-2007-CORRESPONDENCE(IPO)-(19-12-2011).pdf

479-mum-2007-correspondence-received.pdf

479-mum-2007-descripiton (complete).pdf

479-MUM-2007-DESCRIPTION(COMPLETE)-(14-3-2007).pdf

479-MUM-2007-DESCRIPTION(GRANTED)-(19-12-2011).pdf

479-MUM-2007-DRAWING(14-3-2007).pdf

479-MUM-2007-DRAWING(GRANTED)-(19-12-2011).pdf

479-mum-2007-drawings.pdf

479-MUM-2007-FORM 1(14-3-2007).pdf

479-MUM-2007-FORM 18(22-5-2007).pdf

479-MUM-2007-FORM 2(COMPLETE)-(14-3-2007).pdf

479-MUM-2007-FORM 2(GRANTED)-(19-12-2011).pdf

479-MUM-2007-FORM 2(TITLE PAGE)-(14-3-2007).pdf

479-MUM-2007-FORM 2(TITLE PAGE)-(GRANTED)-(19-12-2011).pdf

479-MUM-2007-FORM 26(14-5-2010).pdf

479-MUM-2007-FORM 26(28-4-2010).pdf

479-MUM-2007-FORM 3(14-3-2007).pdf

479-MUM-2007-FORM 3(14-5-2010).pdf

479-MUM-2007-FORM 3(28-4-2010).pdf

479-MUM-2007-FORM 5(14-3-2007).pdf

479-MUM-2007-FORM 5(14-5-2010).pdf

479-MUM-2007-FORM 5(28-4-2010).pdf

479-mum-2007-form-1.pdf

479-mum-2007-form-2.doc

479-mum-2007-form-2.pdf

479-mum-2007-form-3.pdf

479-mum-2007-form-5.pdf

479-MUM-2007-PETITION UNDER RULE 137(24-10-2011).pdf

479-MUM-2007-REPLY TO EXAMINATION REPORT(14-5-2010).pdf

479-MUM-2007-REPLY TO FIRST EXAMINATION REPORT(28-4-2010).pdf

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Patent Number

250242

Indian Patent Application Number

479/MUM/2007

PG Journal Number

51/2011

Publication Date

23-Dec-2011

Grant Date

19-Dec-2011

Date of Filing

14-Mar-2007

Name of Patentee

NABALTEC AG

Applicant Address

ALUSTR. 50-52, 92421 SCHWANDORF,

Inventors:

#	Inventor's Name	Inventor's Address
1	ALFRED REIMER	Jagerweg 2, 92437 Furth im Wald,
2	REINER SAUERWEIN	Pfaffenberg 1, 92449 Steinberg
3	MANFRED SORGALLA	WohlerstraBe 2, 92424 Schwandorf,
4	LUDWIG EDENHARTER	OrffstraBe 3, 93133 Burglendgenfeld

PCT International Classification Number

C01F7/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	DE102006012268.2	2006-03-15	Germany