Note: Descriptions are shown in the official language in which they were submitted.
WO 95/21882 2 1 8 3 0 6 8 PCTIUS9~101900
' .
COPOLYMERS OF POLYASPARTIC ACID AND POLYCARBOXYLIC ACIDS AND POLYAMINES
FIELD OF 71 iE INVENTION
This invention relates to a process for the production of copolymers of polysuccinimide, their
convcrsion to saits of copolymers of polyaspartic acld and the use of these materbls.
BACKGROUND OF THE INVENnON
ruly~._,~. IW acid is a peptide chain in which amide linkages extend the chain. In the thenmal
pu!~ d~iUI I of aspartic acid, the ~ u~,l, y of the aspartlc ac!d is racemized and the formation
ûf both a and B carboxyiic acid groups have the ability to react to form such amide bonds. Such
materials have been used for fertilizers and scale inhibitlon a3ents. They are particulariy useful fûr the
1 û prevention of scale deposition in boiler water, reverse osmosis membranes, detergents and as inhibitors
of dental tartar and plaque formation (tartar banrier agents). These materials are readily ~
Methods for the preparation of polyaspartic acid have been developed (See U.S. Patent Nos. 5,û57,597
and 4,839,461 and U.S. Patent Application Ser. No. û7/832,919, filed May 14, 1992, Louis ~. Wood, and
U.S. Patent Application Ser. No. 07/926,242, filed August 7, 1992, Louis L. Wood).
'" l~ y, calcium ion exchange ability and the disruption of calcium salt crystal structure
are important properties of materlals used In the preventlon of scale deposition in boiler water, on
reverse osmosis membranes, in detergent use and as inhibitors of dental tartar and plaque fonmatlon
(tartar barrier agents). We searched fûr e '1~ useful materiais, havinq a greater retention on
the object wherein inhibition of scale depositlon Is desired. Other desirable properties were greater
stability to ' ~-O ' , in addition to intrinsic value for the preventlon of scriie deposition in boiier
water, on reverse osmosis membranes, during detergent use and as inhibttors of dental tartar and plaque
formation (tartar banrier agents). We have found that the addltlon of pu!~ U~l L~ux~ " acids in the thermal
pu'yr, ' ' of maieic acid or aspartic acid produced novei and hlghly effective copolymers whlch
possessed these properties.
Ut:~;l 1 l OF RELATED ART
A number of methods of preparation of polyaspartic acid are disclos~ ~ ,n the iitenature and other
patents, however, no mention is made of methods of preparation of copolymers of polyc~ ~ ' ' and
pcl~ ' ;" acids which may then be converted to copolymers of polyaspartlc acid and
, l~ L ," acWs.
SUMMARY OF Ti iE INVENTION
Copolymers of pul~ ~ ' ' '' were prepared by reacting maleic acld, ammonla and a
j '~ , ," acid at ' , __ greater than 12a'C. These copoiymers could be converted to
copoiymers of polyaspartic acid by addition of a hydroxide.
~, in a second ell ' " ,~ of the invention, copolymers of pu!~ u~ were prepared by
reacting maielc acid, ammonia, a ~ul~. ~ ," acid and a polyamine at temperatures greater than
12FC. These copolymers could be converted to copoiymers of poiyaspartic acid by addition of a
hydroxlde.
One ob~ect of thls invention is to provWe a means of preparing copolymers of pul~. ' ' '
W095121882 218~n68!' PCT~S94/01900
A further object of this invention is to provide a means of preparing copolymers of polyaspartic acid.
Yet another object of thjs invention is to provWe novel ~ , which are useful for the inhibition
of salt depositlon, especially bivalent metal salts, whether in water treatment, detergent addition, onal
health care or cosmetic fommulation. Yet anolher object of this invention is to provide novel
5 . , ' ' .~ whlch may be further reacted to provide useful compounds ~u, I" ,1, cosmetics,
oral health care and detergents.
DETAILED ~tS-;Hlr I : OF THE I 'ITS.
Copolymers of polyaspartic acid which are suitable for the inhibition of scale deposition may be
obtained by reacting maleic acid, an additionai pu'!,~,Lux~'' acid and ammonia in a ~tui~ iu,,,t:lli..
eXcQSs, at 12cf -35a C., prQferably 18a'-30Cr C., and then converting the copolymer of polysuccinimide
formed to a salt of a copolymer of poiyaspartic acW by hydrolysls wHh a hydroxWe.
in a second tJIIILU i~ 1, copoiymers of polyaspartic acid which are suitabie for the inhibitlon
of scale deposition may be obtainQd by reacting maieic acld, an additionai poi~c ' , " acld, ammonia
in a ;.Iu;..I,iu"le~ , Qxcess. and a compound having 2 or more primary or secondary amine groups per
moiecule, at 1207-350' C., preferably 180'-3ûi~ C., and then converting the copolymer of
i~ ' ' ' ' fonmed to a sait of a copdymer of poiyaspartic acW by hydrolysis with a hydroxidQ
Thereaction~scarriedoutfirstbytheadditionofwatertomaieicanhydride,thusformingmaleic
acid,ortomaleicacWitself,andthej,ul~c L ,~ acid,followedbyaddaionoftheappropriateamount
of ammonia in the form of gaseous ammonia or as its aqueous soiution. At this point, the poiyamine
may be added to either of these aiternative '. '' This solution is then heated to remove water.
As water is removed, the mixture becomes a soild and then a meit of the mixture is fommed. Water
removal continues as the reaction proceeds and the temperature is brought to 120~-30c~ C. When the
theoreticai quantity of water fonmQd in the production of the copolymer of p-,!j~ ' ' .i id has been
removed, which, dependinq on the temperature, may occur in even iess than 5 minutes, the reaction
mixture is aiiowed to cool. Typically, it may take over 4 hours at 1 2cr C, whereas it may take iess than
5 minutes at 300' C. The copolymer of poiysuccinimide formed can be used to make other novei and
useful products by reacUons such as those described in U.S. Patent 4,363,797 or U.S. Patent 3,486,380,
wherein useful derivatives for cosmQic use are described. The copoiymers of uu~ can aiso
underso aikaline hydroiysis to provide the appropriate sait of a copoiymer of poiyaspartic acid. Further
1~ ' to remove the water or the salts can be canied out to provWe water free powders of the
saits or the free acW.
The polyamines which may be used to produce thQse copoiymers of this invention have been
described in U.S. Patent Application Ser. No. 07/926,242, filed Aug. 7, 1992, Louis L Wood,
~l herein by rQference, are amines which have at ieast two or more primary or secondary
amines availabie for reaction. PrefenrQd polyamines have at ieast two primary amine ciroups. The
CU~ t rt' .~1 may ran~qe from qreater than 0 to 50%, however, the preferred range is çireater than 0 to
3096.
Any aiiphatic or aromatic ~u!~. ' ," acW may be used in this invention, but the preferred
Wo 95/21882 2 ~ ,S ~ PCTIUS9~/01900
acids are adipic acid, cKric acid, fumaric acld, malic acid, malonic acid, succinic acid, glutaric acid,
oxalic acW, pimelic acid, Kaconic acid, nonanedioic acid, ~iuiecz,.~liûll, acid, octanedioic acld,
isophthalic, terphthalic and phthalic acid. The cu,.c ,. - , may ranDe from greater than û to 50%,
however, the preferred range is greater than 0 to 30%.
The hydroxldes useful in convertlng the copolymers of pul~ formed above to
copolymers of polyaspartic acld include, but are not limKed to, the alkali and alkaline earth metals and
ammonia, examples of which as their cations are, Na+, i<+, Mg+, Li+, and Ca++, Zn++, Ba++, Co++, Fe++,
Fo+++, and Ni l,+.
ru'~.uccll l' ' ' is the im'lde form of polyaspartic acid and is also known as a~ ' u,uuly~ w
0 acid.
The ~rm suecinimide" Is qnderstood in the art to include many of the amide, ~mlde and amidine
species which are also formed by this reaet~on. The i~ I produet however is succlnimlde and
this temm is used to refer to the thermally polymerized reactlûn product of maleic acld and ammonia or
a polyamlne. The polyaspartic moletles formed by hydrolysis of the i u!~ ~ formed would be
pr~ncipailya and B aspariates.
The eopoiymers of pr~iyaspartie aeW provlded by the present Inverltion are advantageous for
inhibK~on of seaie deposKion In ~ ~ t, as detergent addKives, In orai health eare or ~n eosmetic
fommulatlon. Solutions of thQ salts of eopolymers of polyaspartic acld formed in this manner have
excellentscalelnhlbKloni._.lu,,,,..,,~,~. SaltswhlehmaybelnhlbKedarethesaitsofMg,Ca,Sr,Ba,and
Ra. The earbonate, sulfate and phosphate salts are those In whleh greatest ~nhibKlon Is shown.
The following examples are by way of illustration and not by way of limitation.
EXAMPLE 1
Preparation of a polyaspartic acid/eKrie acid copolymer.
A slurry of 19.6 9 (0.2 mole) maielc anhydride was dlssolved in '+0 ml water at 80~-9S C. and
2S 4.2 9 (0.02 moles) of cKric acW ,,,u--ol,; (Formula welght 210) was added and the mixture was
stlrred until all sollds were in soiutlon, after whlch the mixture was allowed to cool to 25 C. To this
solutlon at 2S C. was added 60 9 of 30% aqueous soiutlon of ammonlum hydroxlde (0.44 mol Ni~).
Th~s solutlon was evaporated to dryness over a per~od of 8 minutes. The sdld was then heated at 235 -
245 G for S minutes, removed from the heat, allowed to cool and broken up wKh a spatula. The solld
was then heated at 235 -245 C. for a second 10 minute pefiod, removed from the heat, ailowed to cool
and broken up with a spatula. Finaily, the solW was heated at 235 -245 C. for a thlrd 10 minute pefiod,
removed from the heat and allowed to cool to room temperature. The resultlng water Insoluble
eopolyrner of polysucelnlmWe and eKric acW (21.7 9) was slurfied In 29.1 ml df water and a solutlon of
8.0 g of sodium hydroxide In 12 ml d water vJas added over 5 minutes. The solutlon was stirred for 10-
3,S 20 mlnutes to give a elear red-brown solution df a eopolymer of polyaspartic acld and eKrle aeW.
EXAMPLE 2
Preparatlon of a polyaspartic acid/suecinic acld eopolymer.
A slurry of 1Q6 ~ (0.2 mde) malele anhydrlde was dlssolved in ~iO ml water at 8~-QS C. and
2 9 (0.02 moles) of sucelnle anhydfide (Formula weii3ht 100) was added and the mixture was stirred until
W0 95/21882 ~ PC~/US9 ilO19oo
all solids wore in solution, after which the mixture was allowed to cool to 2S C. To this solution at 2s
C. was added 60 9 of 30% aqueous solution of ammonium hydroxide (0.44 mol Ni~). Th~s solution was
ovapon~ted tO dryness over a period of 8 mlnutes. The solid w~as then heated at 235-24S C. for s
minutes, removed from the heat, allowed to cool and brQ,~e~ wKh a spatula. The solid was then
heated at 235-245 C. for a second 10 minute period,'rèmoved from the heat, allowed to cool and
broken up with a spatula. Finally, the solid was heated at 23S-24S C. for a third 10 minute period,
removed from the heat and allowed to cool to room temperature. The resulting water insoluble
copolymer of polysuccinimlde and succinic acid (21.9 g) was slurried in 29.1 ml of water and a solution
of 8.0 9 of sodium hydroxlde in 12 ml of water was added over 5 minutes. The solution was stirred for
10-20 minutes to give a dear red-brown solution of a copolymer of polyaspartic acld and succinic acid.
EXAMPLi~ 3
Precipitation assay for calcium sulfate.
The material to be tested as an inhibhor of scale formation was added in appropriate quantities
to a solution of 5 ml of calcium chloride solutions (21.6 g/L of CaCiz dihydrate and 41.4 ~/L of NaCI)
and 5 ml of sulfate sdution (20.9 s/L of Na2SO~ and 41.4 9 NaCI). The mixture was then placed in an
oven at 160' F for 3 hours. Finally the mixture was filtered through Whatman #2 paper and drled at
160' F for 8 hours, after whlch the welght of preclpitate was detemm~ned.
The ~Jul~. iJUA~' ac~d/~u!~ , 'i( acld copolymers were tested in the above assay. The
results are given below In Table 1.
Table 1
compound ~,u'y~.L ," welght of precipitate
(m~q)
26 acld
blank 44
,uulyr~ ' , 6000 molecular welght 46
copolymer i ul~ , i ' /citrate citric acid 16
30 copolymer pu!~ , /succinate succinlc acid 13
The copolymers of polyaspartic acid and ,uul~ ~ ' , " acWs were very effective aqents for the
Inhibition df mineral scale.
EXAMPLE 4
CrJICjUm oAalate titrr~t~on. ~'`
A 0.26 9 sample d the sodium salt of the pdyaspartic/citrlc acid copdymer prepared in
EA~ample 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 Iclum chlorWe till the sluny turned white.
WO 95/21882 ~ PCTIIIS94101900
and 8.1 ml while a polyaspartic acid prepared from ~ " i.,." maleate required 8.3 and 8.5 ml. This
shows that ~ lJA;~- acid copolymers of polyaspartic acid are effective calcium chelators.
EXAMPbE S
Preparation of ~ . i /cHric acid copolymer wHh a polyamine
A solution of 2.1 9 (0.01 moles) of citric acld ~ ; ' (Formula weight 210) and 0.32 o
(.0028 moles) Il~--~..,i_..,l"~i was added to 19.6 9 (0.2 mole~ malelc anhydride which had been
dissolved in 40 ml water at 8~ -9S C., and finally 30 ~j of 3096 aqueous solution of ammonium hydroxlde
(0.22 mol NH3) was added. This solution was evaporated to dryness over a period of 30 minutes. The
solld wasthen heated at 19S-220' C. for 10 minutes, removed fromthe heat, allowed to cool and broken
up with a spatula. The solld was then heatr~d at 230-24S C. for 10 minutes, removeti from the heat,
ailowed to cool and broken up with a spatula. Finally, the solW was heated at 23a'-24S C. for 10-15
minutes, removed from the heat and allowed to cool to room temperature. The resulting water insoluble
polymer was slurrled in 40.0 ml of water and a solution of 8.0 9 of sodium hydroxide in 12 ml of water
was added over 5 minutes. The soiution was stirred for 10-20 minutes to give a clear red-brown
solution, pH 10-11.0 of a copolymer d polyaspartic acid, citric acid and ' " The tests for
CaSO4, Exampie 3, and CaCO3 (beiow) were run and the result are recorded in Tabie 2.
InhibH~on o~ calcium carbonate, 1, - by the calcium dri~t ~riay.
In this assay a .~ soiution of calcium carbonate is fommed by adding 29.1 ml of O.55
M Naa and 0.01 M Ka to 0.15 ml of 1.0 M Caa2 and 0.3 ml of 0.5 M NaHCO3. The reaction is initiated
by adJusting the pH to 7.5-8.0 by titration with 1 N NaOH and addition of the materiai to be tested for
inhibition df CaCO3 precipitation at a ievel of 1.7 ppm. At three minutes, 10 mg of CaCO3 is added and
the pH is recorded. The decrease in pH is directiy conrelated to the amount of CaCO3 that precipltates.
TABiE2
Sampie CaSO~ CaCO3
ppt Driit
(m9) (pH units)
none 84 .72
copdymer 74 .26
These assays indicate that the copoiymer of Example 5 is elfective in prevention of CaSO4 and
CaCO3 scale.
The following examples wiii serve to Dlustrate the tartar barrier , ' d this invention.
Copoiymers of Examples 1, 2 and 5 are suitabie tariar banrier agents. Humectants are materiais such
Wo9~/2188Z ~ 8 PCT/US9~/01900
as ~Iycerol, Foaming agents are suhable surfactants. Sweetenin~ agents may be normal or artlficial
sweeteners. Common abrasives are materiais like iumed silica. Gellin~ a~ents are polymers which are
used to prepare thickened solutions.
t ~ ~?
S EXAMPLE A - Mouthwash %w/w
Tartar barriera~qent 0.S-2
humectant 6.0
foamin~ a~ent 1.0
sweetener 0.3
de~onized water q.s. to 100
flavors 1.0
EXAMPLE B -Abrasive Dentrifice Gel
Tariar barrler a3ent 2-10
detergent 1.5
humectant 10.0
sweetener 0.2
deionized water q.s. to 100
flavors 1.0
abrasive 55.0
gellln~q a~ient 2.0
EXAMPLE C - Chewin~q gum
Tartar barrier a~qent 1.0-11
Gum base 21.3
sui3ar 48.5-58.5
corn syrup 18.2
flavors
It wlll be apparent to those skilled in the art that the examples and ' " described
30 here~n are by way of illustration and not of limitatlon, and that other examples may be utilized whhout
departin~ from the spirh and scope of the present Inventlon, as set forth ~n the appended claims.
