Water soluble crosslinked copolymers, their preparation and their use

Water-soluble copolymers which are obtainable by free-radical solution polymerization of PA1 a) 10-99.5% by weight of at least one vinylimidazole of the formula ##STR1## where R.sup.1, R.sup.2 and R.sup.3 are identical or different and are H, C.sub.1 -C.sub.4 -alkyl, monomers of the formula ##STR2## where R.sup.4 and R.sup.5 are identical or different and are H, C.sub.1 -C.sub.4 -alkyl or together form a ring of 3 to 5 methylene groups, PA2 N-vinyloxazolidone, N-vinyltriazole, 4-vinylpyridine N-oxide or mixtures of said monomers, PA1 b) 0-89.5% by weight of other copolymerizable monoethylenically unsaturated monomers and PA1 c) 0.5-30% by weight of at least one monomer which acts as crosslinker and has at least two non-conjugated ethylenic double bonds in water and/or polar organic solvents in the presence of polymerization regulators, using from 0.1 to 5 parts by weight of polymerization regulator per 1 part by weight of crosslinker, a process for preparing the copolymers by free-radical solution polymerization of the monomers in the presence of polymerization regulators and the use of the copolymers as additive to detergents.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to water-soluble crosslinked copolymers, to a process 
for preparing the copolymers by free-radical polymerization of 
vinylimidazoles, N-vinylamides, N-vinyloxazolidone, N-vinyltriazole or 
mixtures of said monomers, with at least one monomer which acts as 
crosslinker and has at least 2 non-conjugated ethylenic double bonds in 
the presence of polymerization regulators, and the use of the copolymers 
as additive to detergents and cleaners. 
2. Description of the Background 
DE-A 32 09 224 discloses the preparation of insoluble polymers of low 
swellability from basic vinylheterocycles and their copolymers with up to 
30% by weight of copolymerizable monomers and 0.1-10% by weight of 
crosslinkers in aqueous medium in the absence of initiators. As is evident 
from the comparative example in this publication, the polymerization of 
100 parts by weight of N-vinylimidazole and 2 parts by weight of 
N,N'-methylenebisacrylamide in aqueous solution using azoisobutyronitrile 
as polymerization initiator results in firm gels. 
The copolymerization of vinylheterocycles with crosslinkers in aqueous 
solution in the presence of free-radical initiators always results in gel 
formation, see the comparative example in DE-A 40 00 978. As is also 
evident from this reference, polymerization of a vinylheterocycle with a 
crosslinker and with exclusion of oxygen and of polymerization initiators 
results in water-insoluble copolymers which can be used, for example, to 
remove heavy metal ions from wine. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide water-soluble polymers 
based on vinylheterocycles or vinylamides. 
We have found that this object is achieved by water-soluble crosslinked 
copolymers which are obtainable by free-radical solution polymerization of 
a) 10-99.5% by weight of at least one vinylimidazole of the formula 
##STR3## 
where R.sup.1, R.sup.2 and R.sup.3 are identical or different and are H, 
C.sub.1 -C.sub.4 -alkyl, monomers of the formula 
##STR4## 
where R.sup.4 and R.sup.5 are identical or different and are H, C.sub.1 
-C.sub.4 -alkyl or together form a ring of 3 to 5 methylene groups, 
N-vinyloxazolidone, N-vinyltriazole, 4-vinylpyridine N-oxide or mixtures 
of said monomers, 
b) 0-89.5% by weight of other copolymerizable monoethylenically unsaturated 
monomers and 
c) 0.5-30% by weight of at least one monomer which acts as crosslinker and 
has at least two non-conjugated ethylenic double bonds 
in water and/or polar organic solvents in the presence of polymerization 
regulators, using from 0.1 to 5 parts by weight of polymerization 
regulator per 1 part by weight of crosslinker. 
The invention also relates to a process for preparing the water-soluble 
copolymers, which comprises subjecting 
a) 10-99.5% by weight of at least one vinylimidazole of the formula 
##STR5## 
where R.sup.1, R.sup.2 and R.sup.3 are identical or different and are H, 
C.sub.1 -C.sub.4 -alkyl, monomers of the formula 
##STR6## 
where R.sup.4 and R.sup.5 are identical or different and are H, C.sub.1 
-C.sub.4 -alkyl or together form a ring of 3 to 5 methylene groups, 
N-vinyloxazolidone, N-vinyltriazole, 4-vinylpyridine N-oxide or mixtures 
of said monomers, 
b) 0-89.5% by weight of other copolymerizable monoethylenically unsaturated 
monomers and 
c) 0.5-30% by weight of at least one monomer which acts as crosslinker and 
has at least two non-conjugated ethylenic double bonds 
to a solution polymerization in water and/or polar organic solvents in the 
presence of polymerization regulators, using from 0.1 to 5 parts by weight 
of polymerization regulator per 1 part by weight of crosslinker. 
The water-soluble copolymers prepared in this way are used as additive to 
detergents and cleaners. 
DETAILED DESCRIPTION OF THE INVENTION 
The copolymers according to the invention preferably contain as monomers of 
group (a) water-soluble heterocyclic monomers of the formula 
##STR7## 
where R.sup.1, R.sup.2 and R.sup.3 are identical or different and are H, 
C.sub.1 -C.sub.4 -alkyl. The substituents R.sup.1, R.sup.2 and R.sup.3 are 
preferably H, CH.sub.3 and C.sub.2 H.sub.5. 
Examples of monomers of group (a) are 1-vinylimidazole, 
2-methyl-1-vinylimidazole, 2-ethyl-1-vinylimidazole, 
2-propyl-1-vinylimidazole, 2-butyl-1-vinylimidazole, 
2,4-dimethyl-1-vinylimidazole, 2,5-dimethyl-1-vinylimidazole, 
2-ethyl-4-methyl-1-vinylimidazole, 2-ethyl-5-methyl-1-vinylimidazole, 
2,4,5-trimethyl-1-vinylimidazole, 4,5-diethyl-2-methyl-1-vinylimidazole, 
4-methyl-1-vinylimidazole, 5-methyl-1-vinylimidazole, 
4-ethyl-1-vinylimidazole, 4,5-dimethyl-1-vinylimidazole or 
2,4,5-triethyl-1-vinylimidazole. It is also possible to use mixtures of 
said monomers in any desired ratios. The monomer group (a) which is 
preferably used is 2-methyl-1-vinylimidazole, 2-ethyl-1-vinylimidazole, 
2-ethyl-4-methyl-1-vinylimidazole, 4-methyl-1-vinylimidazole or 
1-vinylimidazole. 1-Vinylimidazole and 2-methyl-1-vinylimidazole are very 
particularly preferred. 
Also suitable as monomers of group (a) are compounds of the formula 
##STR8## 
The substituents R.sup.4 and R.sup.5 are H, C.sub.1 -C.sub.4 -alkyl. They 
may also together form a ring of 3 to 5 methylene groups. Examples of 
compounds of formula II are N-vinylformamide, N-vinylacetamide, 
N-methyl-N-vinylacetamide, N-vinylpyrrolidone, N-vinylpiperidone or 
N-vinylcaprolactam. N-vinylpyrrolidone is particularly preferred among the 
compounds of the formula II. Further suitable compounds of group (a) are 
N-vinyloxazolidone, N-vinyltriazole and 4-vinylpyridine N-oxide. It is, of 
course, also possible to use mixtures of said monomers in the 
copolymerization. Monomers of group (a) which are preferably used are 
1-vinylimidazole, 1-vinyl-2-methylimidazole, N-vinylpyrrolidone and 
mixtures of said monomers. The copolymers according to the invention 
contain the monomers in group (a) in an amount of at least 10% by weight, 
normally from 20 to 99.5, and preferably from 50 to 99, % by weight. The 
copolymers preferred for most practical applications are those which 
contain from 85 to 98% by weight of monomers (a) as copolymerized units. 
The copolymers according to the invention may contain other copolymerizable 
monoethylenically unsaturated monomers. Examples of such monomers, which 
can be used singly or mixed with one another in the copolymerization, are 
(meth)acrylates such as methyl, ethyl, hydroxyethyl, propyl, 
hydroxypropyl, butyl, ethylhexyl, decyl, lauryl, isobornyl, cetyl, 
palmityl, phenoxyethyl or stearyl acrylate or the corresponding 
methacrylates, (meth)acrylamides such as acrylamide, N-methylolacrylamide, 
N-tert-butylacrylamide, N-tert-octylacrylamide, N-undecylacrylamide or the 
corresponding methacrylamides, vinyl esters having from 2 to 30, in 
particular 2 to 14, carbon atoms in the molecule, such as vinyl acetate, 
vinyl propionate, vinyl laurate, vinyl neooctanoate, vinyl neononanoate, 
vinyl neodecanoate, styrene, vinyltoluene, .alpha.-methylstyrene, 
unsaturated carboxylic acids such as acrylic acid, methacrylic acid, 
crotonic acid, maleic acid, fumaric acid, itaconic acid or their 
anhydrides, and 2-acrylamido-2-methylpropanesulfonic acid. 
(Meth)acrylates are likewise suitable as monomers (b) when they are derived 
from amino alcohols. These monomers contain a basic nitrogen atom. They 
are used either in the form of the free bases or in neutralized or 
quaternized form. Further preferred monomers are those which contain a 
basic nitrogen atom and an amide group in the molecule. Examples of said 
suitable and preferred monomers are N,N-dialkylaminoalkyl (meth)acrylates, 
eg. dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, 
diethylaminoethyl acrylate, diethylaminoethyl methacrylate, 
dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, 
diethylaminopropyl acrylate and diethylaminopropyl methacrylate. Basic 
monomers which additionally contain an amide group in the molecule are 
N,N-dialkylaminoalkyl(meth)acrylamides, for example N,N-di-C.sub.1 
-C.sub.3 -alkylamino-C.sub.2 -C.sub.6 -alkyl(meth)acrylamides such as 
dimethylaminoethylacrylamide, dimethylaminoethylmethacrylamide, 
diethylaminoethylacrylamide, diethylaminoethylmethacrylamide, 
dimethylaminopropylacrylamide and dimethylaminopropylmethacrylamide. 
Further monomers which have a basic nitrogen atom are 4-vinylpyridine, 
2-vinylpyridine, diallyldi(C.sub.1 -C.sub.12 -alkyl)ammonium compounds and 
diallyl-C.sub.1 -C.sub.12 -alkylamines. The basic monomers are used in the 
copolymerization in the form of the free bases, of the salts with organic 
or inorganic acids or in quaternized form. Suitable for the quaternization 
are, for example, alkyl halides having from 1 to 18 carbon atoms in the 
alkyl group, for example methyl chloride, ethyl chloride or benzyl 
chloride. The quaternization of the nitrogen-containing basic monomers can 
also take place by reaction with dialkyl sulfates, especially with diethyl 
sulfate or dimethyl sulfate. Examples of quaternized monomers are 
trimethylammonioethyl methacrylate chloride, dimethylethylammonioethyl 
methacrylate ethyl sulfate and dimethylethylammonioethylmethacrylamide 
ethyl sulfate. Also suitable are 1-vinylimidazolium compounds which are, 
for example, quaternized with C.sub.1 -C.sub.18 -alkyl halides, dialkyl 
sulfates or benzyl chloride or converted into the salt form with an acid. 
Monomers of this type can be characterized, for example, by the general 
formula 
##STR9## 
where R,R.sup.1,R.sup.2 =H, C.sub.1 -C.sub.4 -alkyl or phenyl, 
R.sup.3 =H, C.sub.1 -C.sub.18 -alkyl or benzyl and 
X.sup.- is an anion. 
The anion in formula III can be a halogen ion, an alkyl sulfate anion or 
else the residue of an inorganic or organic acid. Examples of quaternized 
1-vinylimidazoles of the formula III are 3-methyl-1-vinylimidazolium 
chloride, 3-benzyl-1-vinylimidazolium chloride or 
3-ethyl-1-vinylimidazolium methyl sulfate. It is, of course, also possible 
for the polymers which contain 1-vinylimidazoles of the formula I to be 
partly quaternized by reaction with conventional quaternizing agents such 
as dimethyl sulfate or methyl chloride. 
Compounds preferred as monomers of group (b) are those which have a 
solubility of more than 5% by weight in water at 25.degree. C. If the 
copolymers contain monomers of group (b), they can be present therein in 
amounts of up to 89.5, preferably up to 49.5, % of the weight of the 
polymer. 
A crosslinker is always polymerized into the copolymers. Crosslinkers are 
compounds having at least 2 non-conjugated ethylenic double bonds in the 
molecule. 
Examples of suitable crosslinkers are acrylates, methacrylates, allyl 
ethers or vinyl ethers of at least dihydric alcohols. The OH groups of the 
underlying alcohols can, moreover, be wholly or partly etherified or 
esterified: however, the crosslinkers contain at least two ethylenically 
unsaturated groups. Examples of underlying alcohols are dihydric alcohols 
such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 
1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 2-buten-1,4-diol, 
1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 
1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, neopentyl glycol, 
3-methyl-1,5-pentanediol, 2,5-dimethyl-1,3-hexanediol, 
2,2,4-trimethyl-1,3-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 
1,4-bis(hydroxymethyl)cyclohexane, neopentyl glycol 
mono-(hydroxypivalate), 2,2-bis(4-hydroxyphenyl)propane, 
2,2-bis-4-(2-hydroxypropyl)phenyl!propane, diethylene glycol, triethylene 
glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 
tetrapropylene glycol, 3-thia-1,5-pentanediol, and polyethylene glycols, 
polypropylene glycols and polytetrahydrofurans with molecular weights of 
in each case from 200 to 10 000. Apart from homopolymers of ethylene oxide 
or propylene oxide, it is also possible to use block copolymers of 
ethylene oxide or propylene oxide or copolymers which contain incorporated 
ethylene oxide and propylene oxide groups. Examples of underlying alcohols 
with more than two OH groups are trimethylolpropane, glycerol, 
pentaerythritol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, triethoxycyanuric 
acid, sorbitan, sugars such as sucrose, glucose, mannose. It is, of 
course, also possible for the polyhydric alcohols to be used after 
reaction with ethylene oxide or propylene oxide as the corresponding 
ethoxylates or propoxylates. The polyhydric alcohols can also be initially 
converted into the corresponding glycidyl ethers by reaction with 
epichlorohydrin. 
Further suitable crosslinkers are the vinyl esters or the esters of 
monohydric, unsaturated alcohols with ethylenically unsaturated C.sub.3 
-C.sub.6 -carboxylic acids, for example acrylic acid, methacrylic acid, 
itaconic acid, maleic acid or fumaric acid. Examples of such alcohols are 
allyl alcohol, 1-buten-3-ol, 5-hexen-1-ol, 1-octen-3-ol, 9-decen-1-ol, 
dicyclopentenyl alcohol, 10-undecen-1-ol, cinnamyl alcohol, citronellol, 
crotyl alcohol or cis-9-octadecen-1-ol. However, it is also possible to 
esterify the monohydric, unsaturated alcohols with polybasic carboxylic 
acids, for example malonic acid, tartaric acid, trimellitic acid, phthalic 
acid, terephthalic acid, citric acid or succinic acid. 
Further suitable crosslinkers are esters of unsaturated carboxylic acids 
with the polyhydric alcohols described above, for example of oleic acid, 
crotonic acid, cinnamic acid or 10-undecenoic acid. 
Also suitable are straight-chain or branched, linear or cyclic, aliphatic 
or aromatic hydrocarbons which have at least two double bonds, which must 
not be conjugated in the case of aliphatic hydrocarbons, eg. 
divinylbenzene, divinyltoluene, 1,7-octadiene, 1,9-decadiene, 
4-vinyl-1-cyclohexene, trivinylcyclohexane or polybutadienes having 
molecular weights of 200-20 000. Also suitable as crosslinkers are the 
acrylamides and methacrylamides of at least difunctional amines. Examples 
of such amines are diaminomethane, 1,2-diaminoethane, 1,3-diaminopropane, 
1,4-diaminobutane, 1,6-diaminohexane, 1,12-dodecanediamine, piperazine, 
diethylenetriamine or isophoronediamine. Also suitable are the amides of 
allylamine and unsaturated carboxylic acids such as acrylic acid, 
methacrylic acid, itaconic acid, maleic acid or at least dibasic 
carboxylic acids as described above. 
Also suitable are N-vinyl compounds of urea derivatives, at least 
difunctional amides, cyanurates or urethanes, for example of urea, 
ethyleneurea, propyleneurea or tartaramide. 
Further suitable crosslinkers are divinyldioxane, tetraallylsilane or 
tetravinylsilane. It is, of course, also possible to use mixtures of the 
abovementioned compounds. 
The crosslinkers which are preferably used are those which are soluble in 
the monomer mixture. Examples of crosslinkers which are particularly 
preferably used are methylenebisacrylamide, di- and triallylamine, 
divinylimidazole, N,N'-divinylethyleneurea, products of the reaction of 
polyhydric alcohols with acrylic acid or methacrylic acid, methacrylates 
and acrylates of polyalkylene oxides or polyhydric alcohols which have 
been reacted with ethylene oxide and/or propylene oxide and/or 
epichlorohydrin. Very particularly preferred crosslinkers are 
methylenebisacrylamide, N,N'-divinylethyleneurea and acrylates of glycol, 
butanediol, trimethylolpropane or glycerol, or acrylates of glycol, 
butanediol, trimethylolpropane or glycerol which have been reacted with 
ethylene oxide and/or epichlorohydrin. 
The crosslinkers are present in the copolymers in amounts of from 0.5 to 
30, preferably 1 to 20, % by weight of the polymer. Most of the copolymers 
according to the invention prepared to date preferably contain from 2 to 
15% by weight of the crosslinkers. 
Monomers (a), with or without (b) and (c), are copolymerized in a solution 
polymerization in water and/or polar organic solvents. Examples of 
suitable polar organic solvents are water-miscible compounds such as 
tetrahydrofuran, N-methylpyrrolidone, dioxane, dimethyl sulfoxide, 
acetone, glycols such as ethylene glycol, propylene glycol, 
1,4-butanediol, diethylene glycol, triethylene glycol, tetraethylene 
glycol, and block copolymers of ethylene oxide and propylene oxide, and 
etherified polyalkylene glycols which can be obtained, for example, by 
alkylation of alkylene glycols and polyalkylene glycols. Suitable examples 
are glycols or polyethylene glycols containing C.sub.1 -C.sub.4 -alkylene 
end groups. The etherification can take place at one end or both ends. 
Further suitable solvents are alcohols having 1 to 4 carbon atoms or 
acetone. It is possible either to use a single solvent or to carry out the 
copolymerization in the presence of solvent mixtures. Particularly 
preferred solvents are water, C.sub.1 -C.sub.3 -alcohols such as methanol, 
ethanol, isopropanol and n-propanol, and mixtures of said solvents. The 
solvents are normally used in an amount such that the copolymer content of 
the resulting solutions is from 5 to 80, preferably 10 to 60, % by weight. 
The copolymerization takes place in the presence of polymerization 
regulators. Suitable polymerization regulators are described in detail, 
for example, by K. C. Berger and G. Brandrup in J. Brandrup, E. H. 
Immergut, Polymer Handbook, 3rd Edition, John Wiley & Sons, New York, 
1989, pages II/81-II/141. Examples of polymerization regulators are 
halogen compounds such as tetrachloromethane, chloroform, 
bromotrichloromethane, bromoform, allyl compounds such as allyl alcohol or 
2,5-diphenyl-1-hexene, aldehydes, formic acid, its salts or esters. 
Regulators which contain sulfur in bound form are preferably used. 
Examples of compounds of this type are inorganic bisulfites, disulfites and 
dithionites or organic sulfides, disulfides, polysulfides, sulfoxides, 
sulfones and mercapto compounds. The following polymerization regulators 
are mentioned as examples: di-n-butyl sulfide, di-n-octyl sulfide, 
diphenyl sulfide, thiodiglycol, ethylthioethanol, diisopropyl disulfide, 
di-n-butyl disulfide, di-n-hexyl disulfide, diacetyl disulfide, 
thiodiethanol, di-t-butyl trisulfide and dimethyl sulfoxide. Compounds 
which are preferably used as polymerization regulators are mercapto 
compounds, dialkyl sulfides, dialkyl disulfides and/or diaryl sulfides. 
Examples of these compounds are ethyl thioglycolate, cysteine, 
2-mercaptoethanol, 3-mercaptopropanol, 3-mercapto-1,2-propanediol, 
4-mercaptobutanol, mercaptoacetic acid, 3-mercaptopropionic acid, 
mercaptosuccinic acid, thioglycerol, thioacetic acid, thiourea and alkyl 
mercaptans such as n-butyl mercaptan, n-hexyl mercaptan or n-dodecyl 
mercaptan. 
Mercapto alcohols and/or mercapto carboxylic acids are preferably used as 
regulators in the copolymerization. In order to obtain water-soluble 
copolymers, from 0.1 to 5, preferably 0.2 to 2, in particular 0.25 to 1, 
parts by weight of a polymerization regulator are used per 1 part by 
weight of a crosslinker. 
The monomers undergo free-radical copolymerization in a solution 
polymerization. The copolymerization is initiated by using the 
free-radical polymerization initiators customarily used in such processes. 
Free-radical initiators are all conventional peroxy and azo compounds, for 
example peroxides, hydroperoxides and peroxy esters, such as hydrogen 
peroxide, dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl 
hydroperoxide, diacyl peroxides such as dilauroyl peroxide, didecanoyl 
peroxide and dioctanoyl peroxide, or peresters such as tert-butyl 
peroctanoate, tert-butyl perpivalate, tert-amyl perpivalate or tert-butyl 
perneodecanoate, and azo compounds such as 2,2'-azobis(2-amidinopropane) 
dihydrochloride, 2,2'-azobis2-(2-imidazolin-2-yl)propane! 
dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), 
2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 
2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobis(isobutyrate), 
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 
1,1'-azobis(1-cyclohexanecarbonitrile), 
2,2'-azobis(2,4,4-trimethylpentane) or 2-(carbamoylazo)isobutyronitrile. 
It is, of course, also possible to use mixtures of initiators or the known 
redox initiators. Examples of redox initiators are combinations of at 
least one peroxy compound such as potassium, sodium or ammonium 
persulfate, sodium hypochlorite, sodium perborate, sodium percarbonate, 
hydrogen peroxide, tert-butyl hydroperoxide or di-tert-butyl peroxide and 
at least one reducing agent such as ascorbic acid, lactic acid, citric 
acid, sodium sulfate, sodium bisulfite, acetone sulfite, sodium 
dithionite, sodium hydroxymethylsulfinate or a tertiary amine such as 
dimethylphenylamine. The initiators which are preferably used are those 
which have a solubility of more than 5% by weight in water, methanol, 
ethanol or isopropanol at 25.degree. C. The initiators are used in the 
conventional amounts, for example from 0.1 to 5% of the weight of the 
monomers to be polymerized. 
The copolymerization is carried out by conventional techniques of solution 
polymerization, eg. by batch polymerization in which monomers (a) and (c), 
with or without (b), polymerization regulator and initiator are introduced 
into a solvent and heated to the polymerization temperature. The reaction 
mixture is preferably stirred at the polymerization temperature until more 
than 99.9% of the monomers have reacted. It is also possible in this 
process for the polymerization initiators to be added only after the 
polymerization temperature has been reached. 
Further variants of the process are feed methods, which are preferably 
used. These entail one or all reactants being added, wholly or partly, 
batchwise or continuously, together or in separate feeds, to a reaction 
mixture. Thus, for example, a solution of the polymerization regulator and 
an initiator solution can be added continuously or batchwise to a mixture 
of the monomers and a solvent at the polymerization temperature within a 
given time. However, it is also possible to meter a mixture of regulator 
and initiator into the initial mixture which has been heated to the 
polymerization temperature. Another variant comprises adding the initiator 
to the initial mixture below or at the polymerization temperature, and 
feeding the regulator or a solution of the regulator into the reaction 
mixture within a preset time only after the polymerization temperature has 
been reached. In another variant, the initiator and the crosslinker (c) 
are added to a mixture of regulator, monomers (a) with or without monomers 
(b) and a solvent after the polymerization temperature has been reached. 
It is also possible to heat the initial mixture to the polymerization 
temperature and then add the regulator, initiator and monomers (c) in 
separate feeds or together. It is, of course, also possible to add the 
regulator, initiator, monomers (c) and monomers (a) with or without 
monomers (b) to an initial mixture which has been heated to the 
polymerization temperature. Water or a mixture of water and at least part 
of monomers (a), with or without (b) and further components, is preferably 
used as initial mixture. A procedure in which the polymerization 
regulators are metered continuously or in portions into the monomers 
during the polymerization is particularly preferred. 
The concentration of monomers in the reaction medium is normally from 10 to 
60 and preferably from 20 to 45, % by weight. The polymerization is 
carried out in such a way that there is no visible gelling of the reaction 
mixture. If gelled particles are formed, they have a diameter of less than 
1 mm, preferably less than 500 nm, determined by measurement of scattered 
light in the chosen reaction medium. The resulting copolymers form 
homogeneous solutions in the reaction medium. They have K values of from 
10 to 300 (determined by the method of H. Fikentscher in aqueous solution 
at 25.degree. C. with a polymer concentration of 1% by weight). The 
polymerizations are normally carried out at from 30 to 150, preferably 
from 50 to 120, .degree.C. 
The preparation of polymers which (formally) contain 4-vinylpyridine 
N-oxide as copolymerized unit is preferably carried out by 
copolymerization of 4-vinylpyridine followed by N-oxidation of the 
pyridine ring with, for example, peracetic acid prepared in situ. 
The mixtures resulting in the polymerization can be subjected to physical 
or chemical treatment thereafter. Examples are the known processes for 
reducing residual monomers, such as addition of polymerization initiators 
or mixtures of a plurality of polymerization initiators at suitable 
temperatures or heating the polymerization solution to temperatures above 
the polymerization temperature, treatment of the polymer solution with 
steam or stripping with nitrogen or treatment of the reaction mixture with 
oxidizing or reducing reagents, adsorption processes such as adsorption of 
impurities on selected media such as active carbon or ultrafiltration. 
Conventional workup steps may also follow, for example suitable drying 
processes such as spray, freeze or drum drying, or agglomeration processes 
following the drying. The mixtures with low residual monomer contents 
obtained by the process according to the invention can also be marketed 
directly. 
The copolymers are used, for example, as additive for pharmaceutical or 
cosmetic compositions, as adhesive additive, as additive in paper 
manufacture, for stabilizing enzymes or for adsorbing metal ions, dyes or 
acids. The particularly preferred use is as additive to detergents. The 
effect of copolymers in the washing of colored and white textiles is to 
inhibit color transfer to the uncolored textiles. 
The crosslinked polymers of N-vinylimidazole and N-vinylpyrrolidone are 
particularly suitable for use in heavy-duty detergents because they are 
distinctly more effective than soluble polymers when the dye 
concentrations in the wash liquor are low. However, as a rule, the laundry 
washed in commercial washing is mainly white and slightly colored, plus 
laundry with very wash-resistant coloring. Laundry which releases dye to a 
high degree is, as a rule, present only inadvertently, and thus as a very 
small proportion, in the laundry, eg. if a colored sock is included in the 
wash. The crosslinked copolymers, which bind small amounts of dye 
distinctly more strongly than water-soluble color-transfer inhibitors, 
thus have a great advantage on use by comparison with the water-soluble 
products. 
The detergents can be in powder form or in liquid formulation. The 
detergent and cleaner composition may vary widely. Detergent and cleaner 
formulations normally contain from 2 to 50% by weight of surfactants, with 
or without builders. These data apply both to liquid and to powder 
detergents. Detergent and cleaner formulations commonly used in Europe, 
the USA and Japan are tabulated, for example, in Chemical and Engn. News, 
67 (1989) 35. Further details of the composition of detergents and 
cleaners are to be found in Ullmanns Enzyklopadie der technischen Chemie, 
Verlag Chemie, Weinheim 1983, 4th Edition, pages 63-160. The detergents 
may also contain a bleach, eg. sodium perborate or sodium percarbonate, 
which, when used, may be present in amounts of up to 30% by weight in the 
detergent formulation. The detergents or cleaners may contain further 
conventional additives, eg. complexing agents, opacifying agents, optical 
brighteners, enzymes, perfume oils, other color transfer inhibitors, 
antiredeposition agents, soil release polymers and/or bleach activators. 
They contain the copolymers according to the invention in amounts of from 
0.1 to 10, preferably 0.2 to 3, % by weight. 
The K values of the copolymers were determined by the method of H. 
Fikentscher, Cellulose-Chemie, 13 (1932) 58-64 and 71-74, in aqueous 
solution at 25.degree. C. with a polymer concentration of 1% by weight. 
The percentage data in the examples are percentages by weight.

EXAMPLES 
Example 1 
400 ml of water, 50 g of N-vinylpyrrolidone and 50 g of vinylimidazole were 
heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) and 0.3 g of 
mercaptoethanol in 30 g of isopropanol and, in parallel, a second solution 
of 2 g of divinylethyleneurea in 30 ml of isopropanol were added over the 
course of 1.5 hours. The mixture was then stirred at this temperature for 
a further 3 hours. The isopropyl alcohol was subsequently removed from the 
mixture by steam distillation. The result was a clear polymer solution 
with little odor, a solids content of 18.6% and a K value of 23.3. 
Example 2 
400 ml of water and 100 g of N-vinylpyrrolidone were heated while stirring 
with an anchor agitator at 200 rpm in a 1 l apparatus under a stream of 
nitrogen to 80.degree. C. At this temperature, a first solution of 2 g of 
2,2'-azobis(2-methylbutyronitrile) and 2.5 g of mercaptoethanol in 30 g of 
isopropanol and, in parallel, a second solution of 8 g of 
N,N'-divinylethyleneurea in 70 ml of isopropanol were added over the 
course of 1.9 hours. The mixture was then stirred at this temperature for 
a further 2 hours. The isopropyl alcohol was subsequently removed from the 
mixture by steam distillation. The result was a clear colorless polymer 
solution with little odor, a solids content of 17.1% and a K value of 
40.4. N-Vinylpyrrolidone was no longer detectable in the reaction mixture 
by gas chromatography. 
Example 3 
400 ml of water were heated while stirring with an anchor agitator at 200 
rpm in a 1 l apparatus under a stream of nitrogen to 80.degree. C. At this 
temperature, a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) 
and 2 g of mercaptoethanol in 30 g of isopropanol and, in parallel, a 
second solution of 6 g of methylenebisacrylamide, 50 g of 
N-vinylpyrrolidone and 50 g of 1-vinylimidazole were added over the course 
of 2 hours. The mixture was then stirred at this temperature for a further 
3.5 hours. The isopropyl alcohol was subsequently removed from the mixture 
by steam distillation. The result was a clear, pale yellow polymer 
solution with little odor, a solids content of 18.3% and a K value of 
22.0. 
Example 4 
400 ml of water, 50 g of N-vinylpyrrolidone and 50 g of 1-vinylimidazole 
were heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) and 2 g of 
mercaptoethanol in 30 g of isopropanol and, in parallel, a second solution 
of 4 g of divinylethyleneurea in 30 ml of isopropanol were added over the 
course of 1.75 hours. The mixture was then stirred at this temperature for 
a further 3.5 hours. The isopropyl alcohol was subsequently removed from 
the mixture by steam distillation. The result was a pale yellow polymer 
solution with little odor, a solids content of 18.8% and a K value of 
36.8. 
Example 5 
400 ml of water, 50 g of N-vinylpyrrolidone and 50 g of 1-vinylimidazole 
were heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) and 5 g of 
mercaptoethanol in 30 g of isopropanol and, in parallel, a second solution 
of 10 g of divinylethyleneurea in 70 ml of isopropanol were added over the 
course of 1.85 hours. The mixture was then stirred at this temperature for 
a further 3.5 hours. The isopropyl alcohol was subsequently removed from 
the mixture by steam distillation. The result was a clear polymer solution 
with little odor, a solids content of 21.5% and a K value of 24.9. 
Determination of the molecular weight by small angle light scattering in 
0.1 N NaCl solution produced a value of M.sub.W =78 000. This was compared 
with a copolymer of N-vinylpyrrolidone and 1-vinylimidazole in the ratio 
1:1 by weight, which had a K value of 24.4 and had been prepared without 
the addition of N,N'-divinylethyleneurea, which was found to have M.sub.W 
=19 000. Comparison of the two values underlines the branched nature of 
the polymer according to the invention. 
Example 6 
400 ml of water and 100 g of 1-vinylimidazole were heated while stirring 
with an anchor agitator at 200 rpm in a 1 l apparatus under a stream of 
nitrogen to 80.degree. C. At this temperature, a first solution of 2 g of 
2,2'-azobis(2-amidinopropane) dihydrochloride and 5 g of mercaptoethanol 
in 30 g of water and, in parallel, a second solution of 8 g of triethylene 
glycol diacrylate in 50 ml of water were added over the course of 2 hours. 
The mixture was then stirred at this temperature for a further 3 hours and 
subsequently subjected to steam distillation. The result was a pale yellow 
polymer solution with little odor, a solids content of 18.9% and a K value 
of 21.4. 
Example 7 
400 ml of water, 50 g of vinylpyrrolidone and 50 g of 1-vinylimidazole were 
heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 1 g of 2,2'-azobis(2-methylbutyronitrile) and 1 g of 
mercaptoethanol in 30 g of isopropanol and, in parallel, a second solution 
of 2 g of divinylethyleneurea in 30 ml of isopropanol were added over the 
course of 1.5 hours. The mixture was then stirred at this temperature for 
a further 3 hours. The isopropanol was subsequently removed from the 
mixture by steam distillation. The result was a clear polymer solution 
with little odor, a solids content of 27.8% and a K value of 52.3. 
Comparative Example 1 
400 ml of water, 50 g of N-vinylpyrrolidone and 50 g of vinylimidazole were 
heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) and 30 g of 
isopropanol and, in parallel, a second solution of 2 g of 
N,N'-divinylethyleneurea in 30 ml of isopropanol were added over the 
course of 1.5 hours. 45 min after the start of the addition the mixture 
had completely gelled. 
Comparative Example 2 
400 ml of water, 50 g of N-vinylpyrrolidone and 50 g of vinylimidazole were 
heated while stirring with an anchor agitator at 200 rpm in a 1 l 
apparatus under a stream of nitrogen to 80.degree. C. At this temperature, 
a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) and 0.2 g of 
mercaptoethanol in 30 g of isopropanol and, in parallel, a second solution 
of 2.5 g of N,N'-divinylethyleneurea in 30 ml of isopropanol were added 
over the course of 1.5 hours. The mixture gels even during the additions. 
Comparative Example 3 
An experiment using 0.75 g of mercaptoethanol was carried out in the same 
way as Example 2. The result was an aqueous suspension of large gel 
particles. 
Comparative Example 4 
400 ml of water were heated while stirring with an anchor agitator at 200 
rpm in a 1 l apparatus under a stream of nitrogen to 80.degree. C. At this 
temperature, a first solution of 2 g of 2,2'-azobis(2-methylbutyronitrile) 
and 0.5 g of mercaptoethanol in 30 g of isopropanol and, in parallel, a 
second solution of 6 g of methylenebisacrylamide, 50 g of 
N-vinylpyrrolidone and 50 g of vinylimidazole were added over the course 
of 2 hours. Cloudy gel particles formed in the solution during the 
addition of the components. The final result was an aqueous suspension of 
large gel particles. 
Examples of Use 
Test Method 
White cotton test fabric was washed under the conditions specified in Table 
1 with addition of the detergent shown in Table 2 in the presence of dye. 
The dye was either released from cotton test dyeings during the washing 
process or added to the washing liquor as dye solution (see Table 1). 
Table 1 contains the washing conditions for the examples. The composition 
of the detergents used is shown in Table 2. The coloring of the test 
fabric was measured by photometry. The strengths of each of the colorings 
were determined by the method described by A. Kud, Seifen, Ole, Fette, 
Wachse, 119 (1993) 590-594 from the individual reflectance measurements on 
the test fabrics. The inhibiting effect of the test substance on color 
transfer is determined in percent from the color strengths for the test 
with the particular test substance, the color strength for the test 
without test substance and the color strength of the test fabric before 
washing (the inhibition of color transfer is treated in the same way as 
the antiredeposition effect). Tables 3 and 4 shows the efficacies for the 
various dyes. 
TABLE 1 
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Washing conditions 
Test series 1 Test series 2 
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Machine Launder-O-meter 
Cycles 1 
Duration 30 min 
Temper ature 60.degree. C. 
Water hardness 3 mmol/l 
Dye introduction 
solution colored 
fabric 
Test fabric 2.5 g of cotton 
cheese cloth 
(bleached) 
Amount of liquor 250 ml 
Detergent detergent A detergent B 
Detergent 5.0 g/l 4.5 g/l 
concentration 
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TABLE 2 
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Detergent compositions 
Detergent A 
Detergent B 
Ingredients %! %! 
______________________________________ 
Linear Na C.sub.10 /C.sub.13 - 
7.0 8.6 
alkylbenzenesulfo- 
nate (50% strength) 
Na fatty alcohol sulfate 
-- 2.7 
Adduct of 7 mol of 
5.4 -- 
ethylene oxide and 
1 mol of C.sub.13 /C.sub.15 oxo 
alcohol 
Adduct of 10 mol of 
-- 6.3 
ethylene oxide and 
1 mol of C.sub.13 /C.sub.15 oxo 
alcohol 
Zeolite A 27.5 55 
Na citrate 5.5 H.sub.2 O 
-- 9.0 
Soap 1.75 -- 
Ingredients Detergent A 
Detergent B 
%! %! 
Copolymer of 70% by 
3.75 4.0 
weight acrylic acid 
and 30% by weight 
maleic acid, molecular 
weight 70 000 
Na carbonate 15.0 6.0 
Na sulfate 27.75 5.8 
Carboxymethylcellulose 
0.6 0.5 
Water 8.85 -- 
Test substance 1.0 1.0 
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The polymers prepared in the examples were tested in washing series 1 and 
2. The results are shown in Tables 3 and 4. 
TABLE 3 
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Washing series 1 (test with dye solutions) 
Direct 
Direct Direct Direct 
blue black blue orange 
71 22 218 39 
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Polymer 1 97.0% 95.6% 99.8% 17.4% 
Polymer 5 96.7% 92.8% 99.8% 14.4% 
Polymer 6 96.6% 88.1% 99.7% 16.4% 
Comparative 95.6% 79.4% 25.9% 1.5% 
Example 5 
(polyvinylpyrrolidone 
with a K value of 30) 
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TABLE 4 
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Washing series 2 (test with colored fabrics) 
Direct 
Direct Direct Direct 
blue black red orange 
71 22 212 39 
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Polymer 8 (ZK228/36) 
61.2% 83.4% 67.8% 40.7% 
Comparative Example 6 
45.8% 55.6% 43.8% 29.9% 
(polyvinylpyrrolidone 
with a K value of 30) 
Comparative Example 7 
53.5% 66.5% 67.7% 37.9% 
(1:1 vinylpyrroli- 
done/vinylimidazole 
copolymer, K value 18) 
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The washing results in Table 3 show that the copolymers according to the 
invention are very effective inhibitors of color transfer and are 
distinctly superior to the color transfer inhibitor polyvinylpyrrolidone 
which is widely used in detergents. The table also shows that the improved 
effect occurs with many direct dyes and is not confined to a few 
representatives. 
The washing results in Table 4 show that an excellent effect as color 
transfer inhibitor is also found in a test with colored fabrics which 
resembles conditions in practice. Once again, the effect is distinctly 
superior to that of known comparison polymers.