AU740017B2 - Copolymers of polyaspartic acid and polycarboxylic acids and polyamines - Google Patents

Description

Our Ref: 714047 P/00/011 Regulation 3:2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

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Applicant(s): Bayer Aktiengesellschaft D-51368 Leverkusen

GERMANY

Address for Service: Invention Title: DAVIES COLLISON CAVE Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Copolymers of polyaspartic acid and polycarboxylic acids and polyamines The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 COPOLYMERS OF POLYASPARTIC ACID AND POLYCARBOXYLIC ACIDS AND POLYAMINES FIELD OF THE INVENTION This invention relates to a process for the production of copolymers of polysuccinimide, their conversion to salts of copolymers of polyaspartic acid and the use of these materials.

BACKGROUND OF THE INVENTION Polyaspartic acid is a peptide chain in which amide linkages extend the chain. :n the thermal polymerization of aspartic acid, the stereochemistry of the aspartic acid is racemized and the formation of both a and 6 carboxylic acid groups have the ability to react to form such amide bonds. Such materials have been used for fertilizers and scale inhibition agents. They are particularly useful for the prevention of scale deposition in boiler water, reverse osmosis membranes, detergents and as inhibitors of dental tartar and plaque formation (tartar barrier agents). These materials are readily biodegradable.

Methods for the preparation of polyaspartic acid have been developed (See U.S. Patent Nos. 5,057.597 and 4,839,461 and U.S. Patent Application Ser. No. 07/882.919, filed May 14, 1992. Louis L Wood, and U.S. Patent Application Ser. No. 07/926,242, filed August 7, 1992, Louis L Wood).

Biodegradability, calcium ion exchange ability and the disruption of calcium salt crystal structure are important properties of materials used in the prevention of scale deposition in boiler water, on reverse osmosis membranes, In detergent use and as inhibitors of dental tartar and plaque formation (tartar barrier agents). We searched for economically useful materials, having a greater retention on the object wherein inhibition of scale deposition is desired. Other desirable prop. is were greater stability to biodegradation ir. addition to intrinsic value for the prevention of scale deposition in boiler i water, on reverse osmosis membranes, during detergent use and as inhibitors of dental tartar ani plaque formation (tartar barrier agents). We have found that the addition of polycarboxylic acids in tr-e thermal polymerization of maleic acid or aspartic acid produced novel and highly effective copolymers which possessed these properties.

DESCRIPTION OF RELATED ART A number of methods of preparation of polyaspartic acid are disclosed in the literature and other patents, however, no mention is made of methods of preparation of copolymers of polysuccinimide and polycarboxylic acids which may then be converted to copolymers of polyaspartic acid and polycarboxylic acids.

SUMMARY OF THE INVENTION Copolymers of polysuccinimide were prepared by reacting maleic acid, ammonia and a polycarboxylic acid which is not a monoethylenically unsaturated dicarboxylic acid at temperatures greater than 120°C. These copolymers could be converted to copolymers of polyaspartic acid by addition of a hydroxide.

In a second embodiment of the invention, copolymers of polysuccinimide were prepared by reacting maleic acid, ammonia, a polycarboxylic acid which is not a monoethylenically unsaturated dicarboxylic acid and a polyamine at temperatures greater than 120*C. These copolymers could be converted to copolymers of polyaspartic acid by addition of a hydroxide.

ne object of this invention is to provide a means of preparing copolymers of polysuccinimide.

S> 1 P:\WPDOCS\CRN\SPECI\714047.BAY- 28/4/00 Thus, in accordance with the invention there is provided a process for the preparation of copolymers of polysuccinimide comprising reacting maleic acid, a polycarboxylic acid and ammonia at a temperature of 120-350°C with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

In accordance with the invention there is further provided a process for the preparation of copolymers of polysuccinimide comprising reacting maleic acid, a polycarboxylic acid, ammonia and a polyamine at a temperature of 120-350 0 C with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

In accordance with the invention there is also provided a copolymer of polysuccinimide and a polycarboxylic acid prepared by the above described process.

In accordance with the invention there is further provided a copolymer of polysuccinimide, a polycarboxylic acid and a polyamine with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

In accordance with the invention there is further provided a process for the preparation of copolymers of polyaspartic acid comprising reacting maleic acid, a polycarboxylic acid and ammonia at temperatures of 120-350 0 C, and converting the resultant polymer into a salt by adding a hydroxide with the :proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

In accordance with the invention there is further provided a process for the preparation of copolymers of polyaspartic acid comprising reacting maleic acid, a polycarboxylic acid, ammonia and a polyamine, at a temperature of 120-350 0 C and converting the resultant polymer into a salt by adding a hydroxide with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

In accordance with the invention there is further provided a copolymer consisting of polyaspartic acid with a polycarboxylic acid prepared by the above described process.

In accordance with the invention there is further provided a polymer produced by polymerizing (1) maleic acid, ammonia, a polycarboxylic acid and a polyamine with the proviso that said carboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

A further object of this specification is to provide a means of preparing copolymers of polyaspartic acid. Yet another object of this invention is to provide novel compositions which are useful for the inhibition of salt deposition, especially bivalent metal salts, whether in water treatment, detergent addition, oral health care or cosmetic formulation. Yet another object of this invention is to provide novel compositions which may be further reacted to provide useful compounds for water treatment, cosmetics, oral health care and detergents.

(.PWPDocpjmP~crfl4oa1AY 29141e0 DETAIE OESCW IP1 OF IM EMOMNS Copolyners of payaspartic aMp which am =*Mbe Im the hihbion of Male depositon 1m be obined by reacti n aleic: acid. an addftional poywb rlc acid end awarb in a Stoihomti wcess. at i2cr-3=O C, prImbl 10'30 C. ad th cewtng the copolymner cipolysuachikfid Woe toa inmita copalywwrolpoyaspm'tacid byhdwth~v~hydrOddS In. second enfddvhuent.WA -pr not paaparitc adid which am vsM~e for the Mkihlaot' dlside deposition may be obtained b~reactig niadc wl aaddidani pabcobor cid amm"oia, In mr lconvatdc excess. and a comnpouifi haftn 2 o rnore prely or secirdry amnike g 9um per: unlcMe06 at 12(r356 C. Preftrably i1w-aoo C. ard -thn coirvilki the copolymner of palWuciimdeformedto a sa a oymwe tpalyspofaiti *by hydmalysiih a hyd*okde- The reaction Ib carried omtfiiAtby the addiliandwatuerto micaruWd*ide.Owis Iohwrdn nialeic acd. or to naelc acid Itself. and the palycarbeoyfq aciflowed by additionioftileappapdatanmunt ci ammfwda m heform ofgasos amumoria as its aqueou oLo At ttftpohithe polyamnine ,mmybe aided to etherI citese alternatve Irnbodenuis TIM solutinbI then heated to remove woater.

As water Is remroved, the VI*dUUD beconm a sollid and then a mot alf the n*aufe Is fb ad Watterl mmmwal continues as the reaction proceeds and the ugiepeatue Is brougit to 120.aOU Q. When the thOretcal quaity of water formed In the poduction of On copolyr of polysucclnnid has been =wmoed. which, depending on the temratwe irny cr i evn less #oan 5 uuntes, the reactio Is alvdto coa& Typically. It may take ~ve 4 1hows at 117 C wheres It my take less than nxutes =at- QOd M. e copalymrc a ucnnefne can be used to makte ether novel and.

mMSB Products by reacton such as these described i U.S. Patet 4o3.797 or U.S. Patent 3A48C.

wherein useMi dedlvatives fow cosmetic use are described. The copc1ymes of palsuciMide can alsol undergo allarme hydrolysis to provide the appropuiate sait of a copalyMer dt palyaspattic acdL Firther: mnrupulation to remove the water or the salts can be cardied asS to providie water tee powders di thie.

salt or the free acid.

.:The polyamines which may be used to pouc these copolymers of this invention have been described in U.S. Patent Application Ser. No. 07/926.242. fled Aug. 7.,1992. Louis L Wood.

Incorporated herein by reference, are amines which have at least two or more primary or secondary amines available for reaction. Preferred polyamanes have at least two primary amine groups. The may range from greater than 0 to S0%. however, the preferred range Is greater than 0 to Any aliphatic or aromatic polycarbxyic acid may be used in.thi Invention, but the preferred *3 acids are adipic acid, citric acid, fumaric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, itaconic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid. The concentration may range from greater than 0 to however, the preferred range is greater than 0 to The hydroxides useful -in converting the copolymers of polysuccinimide formed above to copolymers of polyaspartic acid include, but are not limited to, the alkali and alkaline earth metals and ammonia, examples of which as their cations are, Na*, KC, Mg Lf, and Ca", Zn", Ba", Co* Fe Fe" and NH'.

Polysuccinimide is the imide form of polyaspartic acid and is also known as anhydropolyaspartic acid.

The term "succinimide" is understood in the art to include many of the p- e, imide and amidine species which are also formed by this reaction. The predominant product ho, ar is succinimide and this term is used to refer to the thermally polymerized reaction prcOuct of maleic acid and ammonia or a polyamine. The polyaspartic moieties formed by hydrolysis of the polysuccinimides formed would be principally a and B aspartates.

The copolymers of polyaspartic acid provided by the present invention are advantageous for inhibition of scale deposition in water treatment, as detergent additives, in oral health care or in cosmetic formulation. Solutions of the salts of copolymers of polyaspartic acid formed in this manner have excellent scale inhibition performance. Salts which may be inhibited are the salts of Mg, Ca, Sr, Ba, and Ra. The carbonate, sulfate and phosphate salts are those in which greatest inhibition is shown.

The following examples are by way of illustration and not by way of limitation.

EXAMPLE 1 Preparation of a polyaspartic acid/citric acid copolymer.

A slurry of 19.6 g (0.2 mole) maleic anhydride was dissolved in 40 ml water at 80 -95 C. and 4.2 g (0.02 moles) of citric acid monohydrate (Formula weight 210) was added and the mixture was stirred until all solids were in solution, after which the mixture was allowed to cool to 25" C. To this solution at 25 C. was added 60 g of 30% aqueous solution of ammonium hydroxide (0.44 mol NH 3 This solution was evaporated to dryness over a period of 8 minutes. The solid was then heated at 235 245" C. for 5 minutes, removed from the heat, allowed to cool and broken up with a spatula. The solid 'was then heated at 235'-245' C. for a second 10 minute period, removed from the heat, allowed to cool and broken up with a spatula. Finally, the solid was heated at 235' -245' C. for a third 10 minute period, removed from the heat and allowed to cool to room temperature. The resulting water insoluble copolymer of polysuccinimide and citric acid (21.7 g) was slurried in 29.1 ml of water and a solution of g of sodium hydroxide in 12 ml of water was added over 5 minutes. The solution was stirred for 20 minutes to give a clear red-brown solution of a copolymer of polyaspartic acid and citric acid.

EXAMPLE 2 Preparation of a polyaspartic acid/succinic acid copolymer.

A slurry of 19.6 g (0.2 mole) maleic anhydride was dissolved in 40 ml water at 80 -95 C. and 2 g (0.02 moles) of succinic anhydride (Formula weight 100) was added and the mixture was stirred until all solids were in solution, after which the mixture was allowed to cool to 25 C. To this solution at C. was added 60 g of 30% aqueous solution of ammonium hydroxide (0.44 mol NH). This solution was evaporated to dryness over a period of 8 minutes. The solid was then heated at 235-2450 C. for minutes, removed from the heat, allowed to cool and broken up with a spatula. The solid was then heated at 235-2450 C. for a second 10 minute period, removed from the heat, allowed to..cool.and broken up with a spatula. Finally, the solid was heated at 2350-245' C. for a third 10 minute period.

removed from the heat and allowed to cool to room temperature. The resulting water insoluble copolymer of polysuccinimide and succinic acid (21.9 g) was slurried in 29.1 ml of water and a solution of 8.0 g of sodium hydroxide in 12 ml of water was added over 5 minutes. The solution was stirred for 10-20 minutes to give a clear red-brown solution of a copolymer of polyaspartic acid and succinic acid.

EXAMPLE 3 Precipitation assay for calcium sulfate.

The material to be tested as an inhibitor of scale formation was added in appropriate quantities to a solution of 5 ml of calcium chloride solutions (21.6 g/L of CaCi dihydrate and 41.4 g/L of NaCI) and 5 ml of sulfate solution (20.9 g/L of NaSO 4 and 41.4 g NaCI). The mixture was then placed in an oven at 16' F for 3 hours. Finally the mixture was filtered through Whatman #2 paper and dried at 160' F for 8 hours, after which the weight of precipitate was determined.

The polycarboxylic acid/polyaspartic acid copolymers were tested in the above assay. The ::results are given below in Table 1.

Table 1 :compound polycarboxylic weight of precipitate (mg) acid *:***blank 44 polyacrylate, 5000 molecular weight 46 topolymer polyaspartate/citrate citric acid 16 topolymer polyaspartate/succinate succinic acid 13 The copolymers of polyaspartic acid and polycarboxylic acids were very effective agents for the inhibition of mineral scale.

EXAMPLE 4 Calcium oxalate titration.

A 0.25 g sample of the sodium salt of the polyaspartic/citric acid copolymer prepared in Example 1 was placed in a beaker with 100 ml of deionized water and 1 ml of 3% sodium oxalate was added. The solution was titrated with 0.1 mol of calcium chloride till the slurry turned white.

and 8.1 ml while a polyaspartic acid prepared from diammonlum maleate required 8.3 and 8.5 ml. This shows that polycarboxylic acid copolymers of polyaspartic acid are effective calcium chelators.

EXAMPLE Preparation of a polyaspartic/citric acid copolymer with a polyamine A solution of 2.1 g (0.01 moles) of citric acid monohydrate (Formula weight 210) and 0.32 g (.0028 moles) hexanediamlne was added to 19.6 g (0.2 mole) maleic anhydride which had been dissolved in 40 ml water at 80 -95 and finally 30 g of 30% aqueous solution of ammonium hydroxide (0.22 mol NH,) was added. This solution was evaporated to dryness over a period of 30 minutes. The solid was then heated at 195 -220 C. for 10 minutes, removed from the heat, allowed to cool and broken up with a spatula. The solid was then heated at 230 -245" C. for 10 minutes, removed from the heat, allowed to cool and broken up with a spatula. Finally, the solid was heated at 230 -245" C. for 10-15 minutes, removed from the heat and allowed to cool to room temperature. The resulting water insoluble polymer was slurried in 40.0 ml of water and a solution of 8.0 g of sodium hydroxide in 12 ml of water was added over 5 minutes. The solution was stirred for 10-20 minutes to give a clear red-brown S solution, pH 10-11.0 of a copolymer of polyaspartic acid, citric acid and hexanediamine. The tests for CaSO 4 Example 3, and CaCO 3 (below) were run and the result are recorded in Table 2.

Inhibition of calcium carbonate precipitation by the calcium drift assay.

this assay a supersaturated solution of calcium carbonate is formed by adding 29.1 ml of 0.55 .M NaCI and 0.01 M KCI to 0.15 ml of 1.0 M CaCl and 0.3 ml of 0.5 M NaHCO 3 The reaction is initiated :by adjusting the pH to 7.5-8.0 by titration with 1 N NaOH and addition of the material to be tested for inhibition of CaCOQ precipitation at a level of 1.7 ppm. At three minutes, 10 mg of CaCO 3 is added and Sthe pH is recorded. The decrease in pH is directly correlated to the amount of CaCQO that precipitates.

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TABLE 2 Sample CaSO 4 CaCO 3 ppt Drift 30(mg) (pH units) none 84 .72 copolymer 74 .26 These assays indicate that the copolymer of Example 5 is effective in prevention of CaSO 4 and CaCO 3 scale.

The following examples will serve to illustrate the tartar barrier compositions of this inventir- Copolymers of Examples 1, 2 and 5 are suitable tartar barrier agents. Humectants are materials SL_1.

as glycerol, Foaming agents are suitable surfactants. Sweetening agents mnay be normal or artificial sweeteners, Commron abeuslves are-materials; like turned sNica Gelling agents are polymers which are used to prepare th~ckened solutions EXAMPLE A MoUthwash %w/W Trtar barrier agerd 0-5-2 humlectant foaming agert sweetene 0.3 110 deionized water q-s. to 100 EXAMPLE B -Abrasive Dmntrlce Gel Tartar bantier agent 2-10 -detergent1.

humectant 10.0 sweeener02 deionized water qs. to 100 flavors abrasive 55.0 geng agent EXAMPLE. C Chewing gum Tartar baffler agent 1.0-11 Gumn base 21.3 Sugar 48.5-58.5 corn syrup 18.2 favrs1 It wil be apparent to tosem skilled in the art that the examples and embodiments describd ~herein are by way of Ilustration and not of limfitation and that other examples may be utilized without departing from the spirit and scope of the present ivntn as set forth"in the appended clairms.

Throughout this specificatio6n and the claims which follow, unless the context requires 9therwise, the word acomprise., or variations such as *comprises" or "comprising% will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an ~0*0acknowledgement or any form of suggestion that the prior art forms part of the common general **knowledge in Australia.

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Claims (26)

1. A process for the preparation of copolymers of polyaspartic acid comprising reacting maleic acid, a polycarboxylic acid and ammonia, at temperatures of 120-350 0 C, and converting the resultant polymer into a salt by adding a hydroxide, with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

2. The process of claim 1 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

3. The process of claim 1 wherein the temperature is 200-300C.

4. A process for the preparation of copolymers of polyaspartic acid comprising reacting maleic acid, a polycarboxylic acid, ammonia and a polyamine, at a temperature of 120-350 0 C and converting the resultant polymer into a salt by adding a hydroxide with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

5. The process of claim 4 wherein the polyamine is selected from the group consisting of those polyamines having at least one primary amine and at least one additional primary or secondary amine.

6. The process of claim 5 wherein the polyamine is selected from the group consisting of diethylene triamine, a polyoxyalkyleneamine diamine or triamine, melamine, an alkyl diamine or triamine, ethylene diamine and hexanediamine.

7. The process of claim 4 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, fumaric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, itaconic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

8. The process of claim 4 wherein the temperature is 200-3000.

9. A copolymer consisting of polyaspartic acid with a polycarboxylic acid prepared by a process according to claim 1. The copolymer of claim 9 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

11. A polymer produced by polymerizing maleic acid, ammonia, a carboxylic acid and a polyamine with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid. P:\WPDOCS\CRN\SPECI\714047.BAY 28/4/00

12. The polymer of claim 11 wherein the polyamine has at least one primary amine and wherein the additional amine group or groups consist of at least one primary or secondary amine.

13. The polymer of claim 12 wherein the polyamine is selected from the group consisting of diethylene triamine, a polyoxyalkyleneamine diamine or triamine, melamine, an alkyl diamine or triamine, ethylene diamine and hexanediamine.

14. The polymer of claim 11 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, fumaric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid. A process for the preparation of copolymers of polysuccinimide comprising reacting maleic acid, a polycarboxylic acid and ammonia at a temperature of 120-350 0 C with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

16. The process of claim 15 wherein the temperature is 200-300 0 C.

17. The process of claim 15 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, Snonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

18. A process for the preparation of copolymers of polysuccinimide comprising reacting maleic acid, a polycarboxylic acid, ammonia and a polyamine at a temperature of 120-350 0 C with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid.

19. The process of claim 18 wherein the temperature is 200-300 0 C. The process of claim 18 wherein the polyamine has at least one primary amine and wherein the additional amine group or groups consist of at least one primary or secondary amine.

21. The process of claim 20 wherein the polyamine is selected from the group consisting of Sdiethylene triamine, a polyoxyalkyleneamine diamine or triamine, melamine, an alkyl diamine or triamine, ethylene diamine and hexanediamine.

22. The process of claim 18 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

23. A copolymer of polysuccinimide and a polycarboxylic acid pepared by a process according to claim 1.

24. The copolymer of claim 23 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimetic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid. A copolymer of polysuccinimide, a polycarboxylic acid and a polyamine with the proviso that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid. P:\WPDOCS\CRN\SPECI\714047.BAY 28/4/00

26. The copolymer of claim 25 wherein the polyamine has at least one primary amine and wherein the additional amine group or groups consists of at least one primary or secondary amine.

27. The copolymer of claim 26 wherein the polyamine is selected from the group consisting of diethylene triamine, a polyoxyalkyleneamine triamine, melamine, an alkyl diamine or triamine, ethylene diamine and hexanediamine.

28. The copolymer of claim 25 wherein the polycarboxylic acid is selected from the group consisting of adipic acid, citric acid, malic acid, malonic acid, succinic acid, glutaric acid, oxalic acid, pimelic acid, nonanedioic acid, dodecanedioic acid, octanedioic acid, isophthalic, terphthalic and phthalic acid.

29. A method of preventing deposition of tartar comprising treating said teeth with an effective amount of a copolymer of polyaspartic acid with a polycarboxylic acid. A method of preventing deposition of tartar on teeth comprising treating said teeth with an effective amount of a copolymer of polyaspartic acid, a polycarboxylic acid, and a polyamine.

31. A method of preventing deposition of scale from mineral containing water comprising the addition of an effective amount of a copolymer of polyaspartic acid with a polycarboxylic acid according to claim 1 to said water. S*.i 32. A method of preventing deposition of scale from mineral containing water comprising the addition of an effective amount of a copolymer of polyaspartic acid, a polycarboxylic acid, and a polyamine, with provisio that said polycarboxylic acid is not a monoethylenically unsaturated dicarboxylic acid. DATED this 27th day of August, 2001 BAYER AG By Its Patent Attorneys DAVIES COLLISON CAVE