Title of Invention	A METHOD ADDITIVE COMPOSITION AND ITS PROCESS FOR MANUFACTURE
Abstract	A wet end additive composition comprising at least one cationic polysaccharide with a degree of substitution (D.S.) from 0.0001-0.04 and at least one cationic polysaccharide with a degree of substitution from 0.05-0.5

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FORM -2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10) A WET END ADDITIVE COMPOSITION AND ITS PROCESS FOR MANUFACTURE HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India GRANTED The following specification particularly describes the nature of the invention and the manner in which it is to be performed. 24-12-2003 1079/MUM/2000 29/11/2000 TECHNICAL FIELD The present invention relates to wet end additives composition for paper manufacture. The wet end additives provide for improved drainage properties, retention of fines and fillers and increased paper strength. BACKGROUND TO THE INVENTION During the manufacture of paper, paper pulp is subjected to mechanical treatment in disintegrators to increase the surface area. Subsequently, the aqueous suspension of the pulp, along with other materials like alum, rosin, fillers and wet-end additives, is filtered on a wire screen (the drainage step). Water drains off through the screen and a fibrous mat is retained on the screen. Wet end additives are added both to improve the quality of the paper as well as to increase the productivity of the paper mills. Thereafter, the fibrous mat is processed in a conventional manner to make paper. A wet-end additive is an additive that aids in removal of water from the pulp during the drainage step. Additionally it provides for retention of fines and fillers and also improves the strength of the paper. Greater removal of water is desired as this results in faster production and lower energy costs. Synthetic wet end additives like cationic polyacrylamide and polyethyleneimine are commonly used in the paper industry. Modified biopolymers, for example, cationic starches are also employed as wet-end additives in the paper industry. Cationic starches are thought to 'fix' onto anionic sites of the pulp and the fillers. This can increase the number of bonds between fibres as well as the fibre and filler giving better strength and retention of fillers. Consequently, the drainage properties, retention of fines and fillers and the strength of the paper are improved. The extent of cationic modification of the polysaccharide and the net anionicity of the pulp influences drainage properties, retention of fines and fillers and paper strength. Amphoteric polysaccahrides can also function as wet-end additives. A combination of an anionic polysaccharide and a cationic polysaccharide can also function as a wet-end additive. The anionic polysaccharide and the cationic polysaccharide form a complex which is usually formed in-situ during papermaking. It is claimed that these complexes improve paper properties. There is, however, a possibility that the net cationic charge available to fix on to the pulp or filler will be lessened by the formation of such complexes. PRIOR ART US5723023 discloses cationic modification of ether or ester modified cationic starches and the use of such starches as wet end additives. The degree of substitution of the cationic group is from 0.005 to 0.2. WO 8301970 discloses a mixture of cationic polysaccharide and polysilicic acid to form a binder complex that imparts improved retention and also improves paper properties. Guar gum with a degree of substitution as high as 1.0 may be used to form a binder complex with the colloidal silicic acid. US 5129989 discloses a process to combine cationic starch with anionic starch to give wet end additives. The polymers act as retention aids. Notwithstanding any other developments in the field, there remains a need in the art for wet end additives that provide improved drainage, better retention of fines and fillers and improved paper strength. It is hitherto not reported in the prior art to impart such properties using a combination of cationic polysaccharides wherein one polysaccharide has a low degree of cationic modification and the other has a high degree of cationic modification. Thus, the applicants have now surprisingly found that a combination of cationic polysaccharides wherein atleast one cationic polysaccharide has a degree of substitution (D.S.) from 0.0001-0.04 and at least one cationic polysaccharide has a degree of substitution from 0.05-0.5 are useful wet end additives. The cationic polysaccharides of the invention shows improved drainage properties retention of fines and fillers and the resulting paper has improved strength. SUMMARY Thus, according to the present invention there is provided a a wet end additive comprising at least one cationic polysaccharide with a degree of substitution (D.S.) from 0.0001-0.04 and at least one cationic polysaccharide with a degree of substitution from 0.05-0.5. The wet-end additives of the invention show improved drainage properties and better retention of fines and fillers and the resulting paper has improved strength. A method of manufacture of the paper in the pH range of 4-10, using the wet-end additive of the invention is also provided for. DEFINITION OF THE INVENTION According to one aspect of the invention, there is provided a wet end additive comprising at least one cationic polysaccharide with a degree of substitution (D.S.) from 0.0001-0.04 and at least one cationic polysaccharide with a degree of substitution from 0.05-0.5. According to a further aspect of the invention, there is provided a process for the manufacture of paper, in a pH range of 4 to 10, involving use of a wet end additive that comprises at least one a) cationic polysaccharide having a degree of substitution from 0.0001-0.04 and at least one b) cationic polysaccharide having a degree of substitution from 0.05-0.5. According to yet another aspect of the invention, the paper manufactured by the above process is provided for. DETAILED DESCRIPTION OF THE INVENTION All parts herein are by weight unless otherwise indicated. THE CATIONIC POLYSACCHARIDE The cationic polysaccharides of the current invention have a) a D.S. from 0.0001 to 0.04 and b) a D.S. from 0.05 to 0.5. The polysaccharides useful for the invention include cellulose, starch, guar gum and tamarind kernel powder. Modified polysaccharides, in particular the esters and ethers of the above mentioned polysaccharides are also understood to be covered by the term polysaccharide. The low D.S. polysaccharide is preferably starch while the high D.S. polysaccharide is preferably guar gum. By starch is meant native starch as well as oxidised starch and the low molecular weight starch obtained by acid or enzyme degradation. The source of the starch includes rice, potato, maize, waxy maize, tapioca, wheat, oat, tapioca and arrowroot. The starch can be in the native form or gelatinised form. The term gelatinisation refers to rupture of the starch granule at elevated temperatures in presence of water. The cationic polysaccharide may be prepared by any of the conventional means known in the literature. An especially preferred process is by spraying the cationic reagent and an alkaline reagent on the polysaccharide. The mixture is heated to obtain the cationic polysaccharide. Cationic starches may be prepared by any of the methods disclosed- in Modified Starches, Properties and Use, OB Wurzburg ed., Chapter 8, pg 113, CRC Press, Florida, 1986. Cationic reagents suitable for the invention are tertiary amino and quaternary ammonium compounds and include epoxy propyl trimethyl ammonium chloride, 3-chloro-2-hydroxy propyl trimethyl ammonium chloride, 3-chloro-2-hydroxy propyl dimethyl dodecyl ammonium chloride, 3-chloro-2-hydroxy popyl dimethyl ocatdecyl ammonium chloride. METHOD OF MANUFACTURE The method of manufacture is as conventionally used in paper mills. Paper pulp is taken in water and disintegrated and refined to the required level depending on the final application. Additives like alum, rosin and fillers are added to the pulp. The pulp is taken over the wire screen where the water is removed (drainage) and the paper is then processed in the conventional manner. The wet end additive of the current invention can be added at any stage during the manufacture of paper, prior to the drainage step. Preferably, the polymers are added as aqueous solutions to the pulp. Preferably the polymers are added together as a blend. If added separately, it is not essential that they be added in any particular sequence. The cationic polysaccharide of D.S. from 0.0001 to 0.04 is preferably added in an amount of 0.01 to 5%, more preferably from 0.1 to 3% and most preferably from 0.3 to 1.5%. The cationic polysaccharide of D.S. from 0.05 to 0.5 is preferably added in an amount of 0.01-5%, more preferably from 0.05 to 2% and most preferably from 0.05 to 0.3%. All percentages are with respect to the weight of the pulp. The wet end additives of the invention are particularly useful when low levels of alum are used in paper making. The invention also relates to the paper produced by this process. Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word "about". The invention is illustrated further by the following non-limiting examples, in which parts and percentages are by weight unless otherwise stated. EXAMPLES The Cationic Polysaccharides Cationic starch (Cato 306, ex Hindustan Lever Limited, India, D.S. 0.03} and cationic guar gum (STARCAT, ex Hindustan Lever Limited, D.S. 0.17) were used as the cationic polysaccharides. COMPARATIVE EXAMPLES A-C, EXAMPLE 1 Cationic starch and cationic guar gum as wet end additives: Furnish mechanical pulp (90% hardwood, 10% softwood) was disintegrated and 1% alum and soap stone were added. The paper pulp was diluted to a consistency of 0.2 g/100 ml and 1 litre of the diluted pulp dispersion was used for drainage study using a Schopper Reigler Freeness tester. Table 1 shows the additives used in each of the examples. Example 1 uses the wet end additive according to the invention. Table 1 Additive Amount (% w.r.t pulp) A B C Example 1 Alum 1 1 1 1 Soapstone 7 7 7 7 CATO 306 0 0.9 0 0.9 STARCAT 0 0 0,1 0.1 Table 2 shows the results of the drainage studies. Table 2 Drainage °SR A 30 B 23 C 25 Example 1 17 The data presented in Table 2 show that a synergistic combination of low D.S. cationic starch and high D.S. cationic guar gum significantly improved the drainage. Properties of paper The properties of the paper prepared by the process described in the invention were studied. Burst factor, breaking length and filler retention (represented by ash content) were determined for the sheets that were prepared. The burst strength was determined using a Bursting Strength Tester, Mullen Type. The values were an average of two paper sheets. For each sheet, an average of four different marked areas was taken. Burst strength is defined by the burst factor which is calculated as follows: Burst Factor = (BS X W X 100)/A Where BS = burst strength W = weight in g of the sheet A = area of the paper sheet in square meters A significant improvement in burst factor indicates an improvement in strength of paper. The breaking length was determined using a tensile stregth tester. Test specimens of 15 mm width were prepared from the paper hand-sheets. The gap was kept at 10 cms. Tests were carried out in triplicate and the average of three values was determined. The higher the value of breaking length, the greater the strength of the paper. The ash content was determined using a known procedure. 2 g of the sheet was taken in a silica crucible and the organic matter was burnt by a Bunsen flame. Then the crucible was heated at 900°C for 2 hrs in a Muffle furnace. The crucible was cooled in a desiccator and the amount of ash was determined. The higher the ash content, the greater the retention of fines and fillers in the paper. COMPARATIVE EXAMPLE D AND EXAMPLE 2 48 g of paper pulp (82% bagasse and 18% softwood) was soaked in 2 litres of water and left overnight for swelling. The soaked pulp was dispersed using a disintegrater. The pulp dispersion was diluted to 24 litres. 1% alum and 2.2% soapstone were added to the pulp. The pH was adjusted to 4.5 and hand sheets were prepared. Comparative Example D was the procedure described above. In Example 2, 0.9% CATO 306 and 0.1% STARCAT were incorporated and the sheets were prepared. The burst factor and ash content was determined and the data are presented in Table 3. Table 3 Wet-end additive in paper Burst factor Breaking length (m) Ash content D 14.5 3150 1.6 Example 2 16.5 3750 2.2 The data presented in Table 3 show that there is a significant improvement in burst factor, breaking length and ash content by using the wet-end additive according to the invention. COMPARATIVE EXAMPLE E AND EXAMPLE 3 Furnish mechanical pulp (95% hardwood, 5% softwood) was disintegrated and 1% alum and soap stone were added. As fillers are lost during pulp processing, the soapstone was so added as to maintain the ash content similar in both examples. Hence, 12 g soapstone was added in Comparative Example E and 8 g of soapstone was added in Example 3. 0.9% of CATO 306 and 0.1% of STARCAT were also added in Example 3. The ash retention was then determined using a similar method as described earlier for the determination of ash content. A higher value of ash retention indicates better retention of fillers (soapstone). Table 4 shows that even after adjusting the amount of soapstone to account for its loss during pulp processing, ash retention is improved in the example of the invention. Table 4 Example Ash Content (%) Ash retention {%) E 5.8 49 Example 3 5.6 69 WE CLAIM: 1. A wet end additive composition comprising at least one cationic polysaccharide with a degree of substitution (D.S.) from 0.0001-0.04 and at least one cationic polysaccharide with a degree of substitution from 0.05-0.5 2. A wet end additive composition as claimed in claim 1 wherein said polysaccharide of D.S. from 0.0001 to 0.04 is in amounts of 0.01 to 5% preferably 0.1 to 3% and more preferably 0.3 to 1.5% by wt. 3. A wet end additive composition as claimed in anyone of claims 1 or 2 wherein said polysaccharide of D.S. from 0.05 to 0.5% is in amounts of 0.01 - 5% preferably 0.05 - 2% and more preferably from 0.05 to 0.3% by wt. 4. A wet end additive composition as claimed in anyone of claims 1 to 3 wherein said polysaccharides are selected from cellulose, starch, guar gum, tamarind kernel powder, modified polysaccharides including esters and ethers of said polysaccharides. 5. A wet end additive composition as claimed in anyone of claims 1 to 4 wherein said low D. S. polysaccharides is preferably starch while the high D.S. polysaccharide is preferably guar gum. 6. A wet end additive composition as claimed in anyone of claims 1 to 5 wherein said starch comprise native starch, oxidized starch and low molecular weight starch obtained by acid or enzyme degradation. 7. A wet end additive composition as claimed in anyone of claims 1 to 6 wherein source of said starch comprise rice, potato, maize, waxy maize, tapioca, wheat, oat, tapioca and arrowroot. 8. A wet end additive composition as claimed in anyone of claims 1 to 7 wherein the starch is in the native form or gelatinized form. 9. A method of manufacture of the wet end additive composition as claimed in anyone of claims 1 to 8 comprising providing selectively a synergistic mix of at least one cationic polysaccharides with a degree of substitution (D.S.)from 0.0001-0.04 and at least one cationic polysaccharides with a degree of substitution from 0.05-0.5 10. A method as claimed in claim 9 wherein the cationic polysaccharides used is prepared by spraying the cationic reagent and an. alkaline reagent on. the polysaccharides and the mixture is heated to obtain the cationic polysaccharide. 11. A method as claimed in claim 10 wherein the cationic reagents used comprise tertiary amino and quaternary ammonium compounds and include epoxy propyl trimethyl ammonium chloride, 3-chloro-2-hydroxy propyl trimethyl ammonium chloride, 3-chloro-2-hydroxy propyl dimethyl dodecyl ammonium chloride, 3-chloro-2-hydroxy propyl dimethyl ocatdecyl ammonium chloride. 12. A process for manufacture of paper in a pH range of 6-11 involving the use of wet end additive as claimed in claims 1 to 8 comprising at least one (a) cationic polysaccharide having a degree of substitution from 0.0001-0.04 and (b) cationic polysaccharide having a degree of substitution from 0.05-0.5 13. A process as claimed in claim 12 comprise providing paper pulp in water and disintegrating and refining to required level depending on the final application, optionally adding additives and fillers to the pulp, removing the water from said pulp and processing in conventional manner. 14. A process as claimed in anyone of claims 12 or 13 wherein the said wet end additive is added at any stage during the manufacture of paper and/or prior to the drainage step. 15. A process as claimed in claim 14 wherein the polymers are added as aqueous solutions to the pulp. 16. A process as claimed in claim 15 wherein the polymers are added together as a blend. 17. A process as claimed in anyone of claims 12 to 16 wherein the cationic polysaccharide of D. S. from 0.0001 to 0.04 is preferably added in an amount of 0.01 to 5%, more preferably from 0.1 to 3% and most preferably from 0.3 to 1.5%. 18. A process as claimed in anyone of claims 12 to 17 wherein the cationic polysaccharide of D. S. from 0.05 to 0.5 is preferably added in an amount of 0.01-5%, more preferably from 0.05 to 2% and most preferably from 0.05 to 0.3%. 19.A wet end additive composition its process of manufacturing and a process of manufacture of paper using said wet end polysaccharides such as herein described and illustrated with reference to the accompanying examples Dated this 27th day of November 2001 HINDUSTAN LEVER LIMITED S. Venkatramani Patents Manager

Documents:

1079-mum-2000-assignment(20-12-2007).pdf

1079-mum-2000-cancelled page(24-12-2003).pdf

1079-mum-2000-claims(granted)-(24-12-2003).doc

1079-mum-2000-claims(granted)-(24-12-2003).pdf

1079-mum-2000-correspondence(ipo)-(8-12-2005).pdf

1079-mum-2000-correspondence1(20-12-2007).pdf

1079-mum-2000-correspondence2(27-11-2001).pdf

1079-mum-2000-form 1(29-11-2000).pdf

1079-mum-2000-form 16(20-12-2007).pdf

1079-mum-2000-form 19(23-6-2003).pdf

1079-mum-2000-form 2(granted)-(24-12-2003).doc

1079-mum-2000-form 2(granted)-(24-12-2003).pdf

1079-mum-2000-form 5(27-11-2001).pdf