Title of Invention

PROCESS FOR THE MANUFACTURE OF AMINOALKYL GROUP CONTAINING GUAR DERIVATIVE

Abstract

The invention relates to guar gum derivatives containing amino alkyl groups and to a method for producing said polysaccharide derivatives by the etherification of free hydroxyl groups of guar gum or guar gum derivatives using dialkylaminoalkyl halides. The invention relates to guar gum derivatives containing amino alkyl groups and to a method for producing said polysaccharide derivatives by the etherification of free hydroxyl groups of guar gum or guar gum derivatives using dialkylaminoalkyl halides.

Full Text

AMINOALKYL GROUP CONTAINING GUAR DERIVATE The invention is with regard to an aminoalkyl group containing guar derivate and a process for the manufacture of this polysaccharide derivate by etherification of free hydroxyl groups of guar or guar derivates with dialkyi aminoalkyi halogenides. Cationic and amino group containing polysaccharides has a multitude of uses e.g., as a paper additive, as a chelating and coagulation aid or as a conditioner for hair. Chitosan, 2-amino-2-desoxy cellulose has a wide range of application possibilities amongst which being an acid-stable thickener in cosmetic preparations is one. Extraction of this natural polysaccharide is, however, a laborious process which is, in turn, reflected in the high price of the product. The high price has, till now, acted as a barrier to the broad application of this polysaccharide and polysaccharide derivate. Some manufacturing possibilities of the aminoalkyi group containing guar derivates are established in prior art. Polysaccharide derivates are described in EP 0 175 113 A2 which are manufactured by transforming polysaccharides or polysaccharide derivates using acetyl group containing substances. In one example, diethylaminoethyl guar with a low substitution degree (DS 0.12) is used as a polysaccharide derivate base. No information has been provided with regard to the features of the diethylaminoethyl guar. A process for the manufacture of diethylaminoethyl guar is described in DE 28 40 011 which is characterised in that the hydrous reaction phase is emulsified with the addition of a tenside in a solvent that does not mix with water. The disadvantage of this process is that a considerable quantity of tenside has to be used. Products that have been stressed by this process have the disadvantage of a lower nnoiecular weight and a markedly lower viscosity when compared to the products in accordance with the invention. The conversion of guar with 0.04 mol diethylaminoethyl chloride per molecule of anhydrous sugar in a hydrous isopropanol is described in example 4 of US 4,276,414. No information has, however, been provided with regard to the features of this minimally substituted diethylaminoethyl guar. Manufacture of alkyl aminoalkyl guar for treatment of effluents is described in US 3,498,912. In this connection, conversions of guar with amines that contain the epoxy or halohydrin (XCH2-CH(0H)-R) groups are preferred since they exhibit a substitution degree DS(N) of 0.01 to 0.5. Higher substitution degrees are more difficult to achieve and are not preferred. Manufacture of the alkyl aminoalkyi guar takes place in an alcoholic solvent. US 2001/0051143 A1 presents cationic modified guar with a DS of 0.25 to 1.0 that is achieved through reaction in an alcoholic medium. Processes and their products established till now, however, exhibit some deficiencies which is why the established processes result particularly in products that are not sufficiently clear-soluble and which, at a particular initial viscosity, exhibit an end viscosity (and correspondingly a low molecular weight) that is too low for many applications. A high molecular weight is important for many applications in which cationic polysaccharide would be employed, examples of which are wastewater treatment or hair conditioning. The object of the invention is, therefore, to develop a cost-effective, highly viscose amino group-containing, high molecular polysaccharide derivate that is clear-soluble even at a low substitution degree. It has now been discovered that dialkylaminoalkyl guar can be manufactured with surprisingly high yield using the etherification process of guar or guar derivates with aminoalkyl chlorides such as e.g., diethylaminoethyl chloride-hydrochloride (DEC) in a slurry process as is described below. The products can be purified with minimum costs and exhibit the following advantages when compared to prior art: 1. These amino group containing polysaccharide derivates dissolve perfectly with a high clear-solubility in cold water. 2. The products have a high molecular weight. 3. The hydrous solvents exhibit a high viscosity. The subject matter of the invention is a process for the manufacture of aminoalkyi group containing guar derivative, characterised in that, a) Guar or a guar derivate disperses in a mixture (slurry) of a water soluble, aprotic solvent and water. b) The guar or guar derivate is alkalised with a base and c) Etherification with an amino group containing reagent at, if required, increased temperature can be executed subsequently and then d) Neutralised, if necessary, and e) The reaction product is, filtered if required, washed if required, dried if required and ground if required. Guar is a flour which is produced by grinding the endosperms of the seeds of the cyamopsis tetragonolobus plant that is indigenous to India. The principal component of guar is guar gum, a non-ionisable polysaccharide from p-(l→4)-glycosidically linked D-mannopyranose unit with a-(1—>6)-linked D-galactopyranose in a side chain and, in fact, one -D-galactose unit for 2 mannose units. Guar derivates, particularly guar ether, could be used in the place of guar. Examples of guar ether are hydroxypropyl guar, hydroxyethyl guar, methyl guar, carboxymethyl guar or guar ether with mixed substituents such as hydroxypropylmethyl guar or hydroxyethylmethyl guar, for example. Solvents that are water soluble and aprotic are used for the slurry medium (slurry = solvent + water) of which ketone or ether are preferred. Of the solvents, acetone, methyl ethyl ketone and dimethoxy ethane are preferred, of which, in turn, dimethoxy ethane is especially preferred. The percentage of the solvent in the reaction medium should be high enough to ensure that the water soluble guar or guar derivate is not dissolved but is dispersed. Similarly, the percentage of water in the reaction medium should be high enough to ensure that the base dunng alkalisation in the reaction medium is at least partially dissolved. A solvent percentage of 40 - 90% in the reaction medium is preferred. The reaction is executed in an agitated tank or in a reaction mixer in the presence of a water soluble, aprotic solvent. The reaction can be executed in an agitated tank if the ratio of polysaccharide to slurry amounts to up to approximately 1:5, preferably approximately 1:15 to 1:6 parts by weight. The charging stock will, should the situation arise, be more difficult to stir at higher ratios of up to approximately 1:4 parts by weight in which case, a reaction mixer can be employed. The latter are e.g. provided under the term All In One Reactor® (Gebr. Loedige Maschinenbau, Division Drais, Mannheim) under the name DRUVATHERM ® reactor (Gebr. Loedige Maschinenbau, Paderborn). These mixers usually consist of a horizontally positioned, mostly cylindrical mixing chamber in which a shaft is located, furnished with a e.g., paddle-shaped or plough blade-shaped mixing element. Particles are ejected from the mixture bed when the shaft turns and swirled and mixed in the chamber above the mixture. The mixer can, if necessary, be furnished with further fixtures such as e.g., so-called milling heads or nozzles. [Karl Sommer in "Mixing of Solids, 3. Designs of Solid - Solid Mixers, 3.3 Paddle Mixers", Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KgaA, 2002. DO! 10.1002/14356007.b02_27, article online posting date: June 15, 2000]. The guar or guar derivate is mixed with a base, preferably an alkali or alkaline earth metal hydroxide of which sodium hydroxide is especially preferred, before addition of the amino group containing reagent. The sequence of addition can, however, also be in the reverse order. The base can, thereby, be added in a solid mass or in the form of a solvent. If solid bases are used exclusively then some amount of water must, should the situation arise, be added since a certain amount of water must be present in the system during alkalisation. If free amines are used then acids that are produced during etherification can be bound by the amino group. At least 0.5 equivalent base per mol amine should, however, be used, particularly preferred is at least 0.7 equivalent, in order to achieve a satisfactory reaction rate. Not more than 1.5 equivalent base per mol amine should be used, preferably not exceeding 1.2 mol and 0.8-1.1 mol in a particularly preferred embodiment. The base quantity must be increased correspondingly if the amino group containing reagent is used in the form of ammonium salts e.g., as a hydrochloride. An equimolar quantity must then at least be used in addition, relating to the ammonium salt, and added to the base in order to release the amine e.g. from the hydrochloride. Compositions of the general formula X-(CH2)n-NR1R2 are suitable as amino group containing reagents, whereby X is an aligning group, preferably chlorine, bromine, iodine or a sulphonic acid residue, whereby R' is an aromatic or aliphatic residue e.g., para-toluyl or methyl, X is, however, preferably chlorine and n must at least be 2, the residues R1 and R2, independent of each other, signify aliphatic or branched or cyclic alkyl or aryl substituents with 1-24 C-atoms or H, if necessary substituted by hetero atoms. Two residues R1 and R2 could, together with the nitrogen, form a ring. Examples of the amino group containing reagents to be used in accordance with the invention are N-(2-chlorethyl)-N, N-diisopropylamine, N-(2-chlorethyl)-N,N-diethylamine, N-(3-chlorpropyl)-N,N-dimethylamine, N-(3-chlorpropyl)-N,N-diethylamine, N-(2-chlorethyl)-N,N-dimethylamine and N-(2-chlorpropyl)-N,N-dimethylamine. Residues R1 and R2 could, together with nitrogen, form a cyclical residue. Examples for the amino group containing reagents used in accordance with the invention that form a ring together with nitrogen in the two residues R1 and R2 are N-(2-chlorethyl)-pyrrolidin, N-(2-chlorethyl)-piperidine and N-(2-chlorethyl)-morpholine. The amino group containing reagents could be employed in the form of ammonium salt e.g., of a hydrochloride. The solid matter as well as a solvent of e.g., 65 wt.% or 50 wt. % in water or another solvent could be used. It is preferable to use N-(2-chlorethyl)-N,N-diisopropylamine,N-(2-chlorethyl)-N,N-diethylamine hydrochloride or N-(2-chlorethyl)-N,N-dimethylamine hydrochloride. Approximately 0.1-3 mol, preferably approximately 0.1-2 mol, especially preferred is approximately 0.3 - 1.5 mol of amino group containing reagents, are used per mol of anhydrous sugar. The reaction is to be executed preferably at temperatures of 40°C to approximately 90°C, especially preferred 60°C to approximately 75°C. The reaction period depends upon the reactor and the amount of amino alkyl derivate used and is in the range of preferably 30 minutes to 4 hours, especially preferred 2 to 4 hours. After the reaction, the product is, if necessary, rid of salts and by-products through filtration. Acids such as amino acids, acetic acids, hydrochloric acids or sulphuric acids are added before or after filtration, if required. The filter cake is, if required, washed with a suitable washing medium. Apart from the water soluble, aprotic solvent, alcohols such as, for example, isopropanol, ethanol or methanol or ketones such as, for example, acetone and their compounds with water have proved their worth as preferred washing mediums. A preferred washing medium is an isopropanol-water compound in the ratio of isopropanol:water 3:2 up to 9:1. Not removing the by-products and using the product in the un-purified form for technical applications is, however, also possible. The product that has been isolated from the reaction medium and, if required, cleaned is, if required, dried and, if required, ground for which purpose commonly available devices can be used. The rate of yield can be calculated in accordance with the formula mentioned in EP-A 0 310 787: Rate of yield (in %) = DStheor./DSgem. DStheor= theoretically possible substitution degree DS, calculated from the molar ratio of the amino group containing reagent to anhydrous sugar DSgem= measured DS, calculated using the formula Mps= molecular weight percentage of a monomer unit of guar in g/mol %N= measured nitrogen value in wt.-% relating to the dry product Mve= molecular weight of the amino group containing reagent in g/mol This formula, however, provides only exact values if the nitrogen content relates only to the amino group containing polysaccharide. Values specified after nitrogen determination (according to Kjeldahl), however, relate to the total volume, corrected, if required, with regard to moisture. A more precise DSgem. can be calculated if the nitrogen value is based on the active content i.e., the measured nitrogen content is corrected with regard to the acids and salts still contained: [ With Ag = active content, based on the total dry mass in % Using the process in accordance with the invention, the amino group containing guar derivate can be manufactured in simple, widespread plants and with a high yield. The transformations can also be executed with a high consistency. The addition of tensides that have to be subsequently removed from the product is done away with. Another advantage is the simple purification of the guar derivate. The products can be easily separated from the slurry medium through filtration and purified heterogeneously. Products of the process in accordance with the invention that present another subject matter of the present invention, deal with the guar derivate in which a part of the hydroxyl groups have been transformed into dialkyl amino alkyl ether groups of the general formula whereby, n must at the least be 2, the residues R1 and R2. independent of each other, signify aliphatic or branched or cyclic alkyl or aryl substituents, if necessary substituted by hetero atoms. Two residues R1 and R2 could, together with the nitrogen, form a ring. The nitrogen of the substituents can, e.g. be present through another transformation with the amino group containing reagent, even in a quaternised form. The guar derivates in accordance with the invention have, in the case of the same molecular weight of the starting material, a higher molecular weight than those that have been manufactured according to prior art. This can be read from the Staudinger Indices of the guar derivate manufactured in accordance with the invention when compared to those products that have been manufactured according to the emulsion process that has been described in DE 2 840 011. A high molecular weight is important for many applications in which cationic polysaccharide could be employed, examples of which are wastewater treatment or hair conditioning. DialkyI amino alkyl guar derivate manufactured in accordance with the invention, furthermore, exhibits a high viscosity at a high clear-solubility when compared to the guar derivate manufactured according to prior art. The product manufactured in accordance with the invention could, for example, be used as hair conditioner in shampoos or as an additive in cosmetic products such as, for example, soaps, creams, lotions or skin or facial cleansers. They can also be used as coagulation aids e.g., in wastewater treatment. These applications of the dialkyl amino alkyl guar derivate in accordance with the invention present a further subject matter of the present invention. The invention is described in greater detail using the following examples without, however, being restricted to the examples. EXAMPLES The DS specified refers to pure dialkyl amino ethyl guar i.e., the total volume has been corrected with regard to the water content, the chloride-ionic content as well as the sodium content. The sodium content has been determined from the sulphur slag under the assumption that this is composed up to 100% from Na2S04. The Staudinger Indices have been determined by measuring the viscosity in a capillary viscosimeter according to Ubbelohde at 20°C in 0.1 M NaCI solution. Evaluation takes place according to Muggins' methods. The charge density relates to the number of quaternised amino groups and has been determined by polyelectrolyte titration against polyethelynesulfoneacidic sodium salts at pH 11.5, The chemicals are freely available in the market. The nitrogen content has been determined based on the Kjeldahl method and based on a repeat determination of the assay. Viscosities have been determined in a solution of 2 wt.-% of the polymers in the case of a shear rate of 2.55 s-1 with a rheometer of the Rotovisko VT 550 type, Fa.Haake. EXAMPLES 1-6: MANUFACTURE OF DIETHYLAMINOETHYL GUAR IN A WATER-DIMETHOXYETHANE SLURRY Guar (53g. dry content 92.18% Staudinger Index: 1392 mL/g.) is suspended in a connpound of dimethoxyethane (647.8g.) and water (96.3g.) in a 1 L glass 4-necked surface ground joint round bottomed concentric-running gadget with an impeller-mixer. The specified quantity of sodium hydroxide is added as a solid and the specified quantity N-(2-chlorethyl)-N,N-diethylamine hydrochloride is added as a hydrous solution (65 wt-%) after 1 h at room temperature and the reaction compound warmed under nitrogen atmosphere to 60°C. The product is washed, dried and ground several times with 80% hydrous isopropanol and finally with pure acetone. COMPARISON EXAMPLES 1-5: MANUFACTURE OF DIETHYLAMINOETHYL GUAR IN A WATER IN OIL EMULSION IN ACCORDANCE WITH DE 2840011 Guar (61 g. dry content 92.18%, Staudinger Index: 1392 mL/g.) is suspended in a compound of octane (200g.) and BRIJ 92 (20g.) in a 500 ml. glass 4-necked surface ground joint round bottomed concentric-running gadget with an impeller-mixer. The specified quantity N-(2-chlorethyl)-N,N-diethyiamine hydrochloride is added as a hydrous solution (65 wt.-%). The specified quantity of sodium hydroxide is then added as a 50% hydrous solution within 45 minutes. The reaction compound is warmed under nitrogen atmosphere to 70°C. After a reaction time of 4 hours, the charging stock is allowed to cool and is neutralised with concentrated hydrochloric acid to pH 4.5. The product is washed, dried and ground several times with 80% hydrous ispropanol and finally with pure acetone. EXAMPLES 7-9: MANUFACTURE OF DIISOPROPYLAMINOETHYL GUAR IN A HYDROUS-DIMETHOXYETHANE SLURRY Guar (53g. dry content 92.18% Staudinger Index: 1392 ml/g.) is suspended in a compound of dimethoxyethane (324 g.) and water (94 g.) in a 1 L glass 4-necked surface ground joint round bottomed concentric-running gadget with an impeller-mixer. The specified quantity of sodium hydroxide is added as a solid mass and the specified quantity N-(2-chlorethyl)-N,N-di-isopropylamine hydrochloride is added as a hydrous solution (65 wt.-%) after 1 h at room temperature and the reaction compound is warmed under nitrogen atmosphere to 60°C. The charging stock is allowed to cool after a reaction time of 4 h and is neutralised with hydrochloric acid (19 wt-%) to pH 6-7. The product is washed, dried and ground several times with 80% hydrous isopropanol and finally pure acetone. EXAMPLES 10-12: MANUFACTURE OF DIMETHYLAMINOETHYL GUAR IN A HYDROUS-DIMETHOXYETHANE SLURRY Guar (88g. dry content, 92.18% Staudinger Index: 1392 mL/g.) is suspended in a compound of dimethoxyethane (540g.) and water (164g.) in a 1 L glass 4-necked surface ground joint round bottomed concentric-running gadget with an impeller-mixer. The specified quantity of sodium hydroxide is added as a solid mass and the specified quantity N-(2-chlorethyl)N, N-dimethylamine hydrochloride is added as a hydrous solution (65 wt.-%) after 1 h at room temperature and the reaction compound is warmed under nitrogen atmosphere to 60°C. The charging stock is allowed to cool after a reaction time of 4 h and is neutralised with hydrochloric acid (19 wt.-%) to pH 6-7. The product is washed, dried and ground several times with 80% hydrous isopropanol and finally with pure acetone. COMPARATIVE EXAMPLES 6-8: MANUFACTURE OF DIETHYLAMINOETHYL GUAR IN A HYDROUS-ISOPROPANOL SLURRY Guar (53g. dry content 92.18%, Staudinger Index: 1392 mL/g.) is suspended in a compound of isopropanol and water according to the quantity specifications listed below in a 1 L glass 4-necked surface ground joint round bottomed concentric-running gadget with an impeller-mixer. 26.4 g. of sodium hydroxide is added as solid matter and 79.4 g.N-(2-chlorethyl)-N,N-diethylamine hydrochloride solution (65 wt.-%) is added after 1 h of mixing at room temperature and the reaction compound is warmed under nitrogen atmosphere to 60°C. The charging stock is allowed to cool after a reaction time of 4 h and neutralised with hydrochloric acid (19 wt.-%) to pH 6-7. The product is washed, dried and ground several times with 80% hydrous isopropanol and finally with pure acetone. Figure 1 presents a comparison of the Staudinger Indices manufactured in 0.1 M NaCI of diethylaminoethyl guar according to the slurry process (examples 1 to 6, Quadrate) in accordance with the invention and according to the established emulsion process according to DE28 40 011 (comparative examples 7 to 11, Rauten). Diethylaminoethyl guar manufactured in accordance with the emulsion process shows a significant fall in the Staudinger Index with increasing substitution degree. In contrast to this, aminoalkyl guar derivate that exhibits high Staudinger Indices even at high substitution degrees and, therewith, high molecular weight, can be manufactured according to the new process. As is clear from the illustration, the Staudinger Indices hardly fall or fall only marginally with increasing substitution degree. Figure 2 presents the viscosities in water (2 wt.-%) of diethylaminoethly guar (examples 1 to 6, Quadrate) manufactured in accordance with the invention, subject to substitution degree DS(N) (average number of amino groups per anhydrous sugar unit). Those guar derivates that have been manufactured according to the above-mentioned emulsion process have also been listed to provide a comparison (comparative examples 7 to 11, Rauten). PATENT CLAIMS 1. Process for the manufacture of aminoalkyl group containing guar derivate, characterised in that, a) Guar or a guar derivate is dispersed in a compound (slurry) of water soluble, aprotic solvent and water and b) The guar or guar derivate is alkalised with a base and c) An etherification is subsequently executed with an amino group containing reagent at, if required, increased temperatures and then d) Neutralised, if necessary, and e) The reaction product is filtered if required, washed if required, dried if required and ground if required. 2. Process in accordance with Claim 1, characterised in that, the water soluble, aprotic solvent is selected from the group comprising acetone, methyl ethyl ketone, dimethoxyethane. 3. Process in accordance with Claim 1 or 2, characterised in that, the amino group containing reagent is a composition of the general formula X-(CH2)n-NR1R2 whereby, X is an aligning group, preferably chlorine, bromine, iodine or sulphonic acid residue R'SO3, whereby R' is an aromatic or aliphatic residue, n must be a whole integer that should at least be 2, the residues R1 and R2, independent of each other, signify aliphatic or branched or cyclic alkyl or aryl substituents with 1-24 C-atoms or H, if necessary substituted by hetero atoms and the two residues K1 ana K2 could, together with the nitrogen, form a ring. 4. Process in accordance with Claim 3, characterised in that, the amino group containing reagent is selected from the group comprising N-(2-chlorethyl)-N,N-diisopropylamine, N-(2-chlorethyl)-N,N-diethylamine or N-(2-chlorethyl)-N,N-dimethylamine or the hydrochlorides of this amine. 5. Process in accordance with one of Claims 1 to 4, characterised in that, the amino group containing reagent is used in a quantity of approximately 0.1-3 mol per mol anhydrous sugar of the guar or guar derivate. 6. Process in accordance with one of Claims 1 to 5, characterised in that, guar ether is used as starting material. 7. AminoalkyI group containing guar derivate, characterised in that, a part of the hydroxyl groups have been transformed into dialkyl amino alkyl ether groups of the general formula O-(CH2)n-NR1R2 whereby, X is an aligning group, preferably chlorine, bromine, iodine or sulphonic acid residue R'SO3, whereby R' is an aromatic or aliphatic residue, n must be a whole integer that should at least be 2, the residues R1 and R2, independent of each other, signify aliphatic or branched or cyclic alkyl or aryl substituents with 1-24 C-atoms or H, if necessary substituted by hetero atoms and the two residues R1 and R2 could, together with the nitrogen, form a ring, have been transformed and this amino alkyl group containing guar derivate exhibits a Staudinger Index > 900 mL/g. and a DS(N) > 0.3. 8. Amino alkyl group containing guar derivate obtainable according the the process in accordance with one of Claims 1 to 6. 9. Amino alkyl group containing guar derivate in accordance with Claim 8, characterised in that, it exhibits a Staudinger Index > 900 mL/g. and a DS(N) > 0.3. 10. Amino alkyl group containing guar derivate in accordance with one of Claims 7 to 9, characterised in that, the amino alkyl groups are present partially in a quaternised form. 11. Application of amino alkyl group containing guar derivates in accordance with one of Claims 7 to 10 for the manufacture of hair conditioners 12. Application of amino alkyl group containing guar derivates in accordance with one of claims 7 to 10 for the manufacture of coagulation aids.

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