Graft copolymers having improved phase binding between the graft base and the grafted-on polymer phase

Graft copolymers having improved phase binding between the graft base and the grafted-on polymer, are prepared from: PA0 a) a grafted-on polymer phase containing one or more monomers from the group consisting of (meth)acrylates of alcohols having 1 to 10 carbon atoms, vinyl esters of saturated aliphatic carboxylic acids having 2 to 10 carbon atoms, olefins, vinyl halides, styrene and styrene derivatives, and PA0 b) a peroxy group-containing copolymer phase containing from 0.01 to 20% by weight of an olefinically unsaturated peroxy compound of the general formula I or II ##STR1## where R.sup.1 is a chemical bond or a linear or branched alkyl chain having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 10 carbon atoms, R.sup.2 and R.sup.3 are an alkyl group having 1 to 4 carbon atoms, R.sup.4 is an alkyl group or an alkyl-substituted phenyl group having 3 to 12 carbon atoms, and R.sup.5 is a cycloalkyl group having 3 to 12 carbon atoms, and from 80 to 99.9% by weight of one or more comonomers from the group consisting of the (meth)acrylates of alcohols having 1 to 10 carbon atoms, vinyl esters of saturated aliphatic carboxylic acids having 2 to 10 carbon atoms, olefins, vinylaromatic compounds, vinyl halides and/or vinyl ethers. The graft copolymers are useful as binders in the textile industry as heat stable binders, as adhesives in plasters and as binders in emulsion paints.

BACKGROUND OF THE INVENTION 
1) Field of the Invention 
The invention relates to graft copolymers having improved phase binding 
between the graft base and the grafted-on polymer phase, to the peroxy 
group-containing copolymers on which these are based, and to 
copolymerizable peroxy monovinyl esters. The invention furthermore relates 
to processes for the preparation of said polymers and peroxy compounds. 
2) Background Art 
Copolymerizable initiators offer interesting opportunities in the 
preparation of novel polymeric materials. By means of such initiators, 
potential free-radical functions which function as defined anchor groups 
in the preparation of graft and block copolymers, are introduced into 
polymer chains. One area of application is, for example, the phase 
coupling of incompatible polymers in core/shell latices during the 
preparation thereof by the emulsion polymerization process. 
Peroxy carbonates containing an allylic double bond and the use thereof as 
comonomers in copolymerization with further ethylenically unsaturated 
monomers are described in DE-A 2726008. German Patent 3420048 relates to 
copolymers of vinyl acetate and peroxyallyl carbonates and the use thereof 
as sizing agents for glass fibers. It is disadvantageous that these 
allyl-functional peroxy carbonates only copolymerize very slowly, if at 
all, with other vinyl monomers. 
EP-A 277608 (U.S. Pat. No. 4,879,347) and EP-A 279430 (U.S. Pat. No. 
4,839,432) describe copolymerizable peroxy carbonates containing (meth) 
acrylate and allyl ether functions as comonomers for improving the phase 
binding in the preparation of polymer blends. The peroxy carbonate is 
polymerized here with vinyl monomers in the presence of an ethylene 
copolymer by the suspension polymerization process. On heating of the 
mixture, coupling of the two polymer phases takes place via the peroxy 
functions. U.S. Pat. No. 4,923,956 describes a procedure which is 
analogous to EP-A 279430, with the difference that propylene polymers are 
employed instead of the ethylene polymers. EP-A 307802 relates to mixtures 
of polypropylene, a further polymer and copolymer made from a vinyl 
monomer and a peroxy carbonate containing an allyl ether or (meth) 
acrylate function; the phase binding thereof being improved by heating to 
temperatures of from 200.degree. to 300.degree. C. EP-B 225091 describes 
allyl ether-substituted peroxy dicarbonates used as initiators for the 
preparation of high-molecular-weight, branched VC polymers. The 
above-mentioned copolymerizable peroxy esters, in particular the allyl 
compounds, have the disadvantage of low reactivity on copolymerization 
with other vinyl monomers. Further more, said peroxy esters can only 
initiate further free-radical reactions from 
temperature.gtoreq.130.degree. C. and are thus of no interest for emulsion 
polymerization. 
The known methylstyrene-based peroxy compound discussed by W. C. Endstra in 
Kautschuk und Gummi, Kunststoffe 42(5), 414 (1989) has the disadvantage 
that it cannot be copolymerized with many vinyl monomers, and further 
free-radical reactions are only initiated thermally from 
temperatures.gtoreq.160.degree. C. The same applies to tert.-butyl-peroxy 
(p-(vinylbenzoyl) benzoates (I. Gupta, S. N. Gupta, D. C. neckers, J. 
Polym. Sci.: Polym. Chem Ed. 20, 147 (1982), which only thermally initiate 
further free-radical reactions from T.gtoreq.100.degree. C. and thus 
cannot be employed for copolymerization by the emulsion polymerization 
process. 
The object was therefore to provide olefinically unsaturated peroxy 
compounds which are copolymerizable with ethylenically unsaturated 
monomers whose peroxy group is retained during the copolymerization and 
whose peroxy groups, after incorporation into the copolymer, are able to 
initiate further free-radical polymerization reactions at 
temperatures.ltoreq.100.degree.. A further object was to provide these 
peroxy compound-containing copolymers and the graft copolymers based on 
the peroxy group-containing copolymers. 
Surprisingly, we have found that this object is achieved by means of peroxy 
monovinyl esters of aliphatic dicarboxylic acids and copolymers or graft 
copolymers containing these peroxy compounds. 
SUMMARY OF THE INVENTION 
The invention relates to peroxy monovinyl esters of aliphatic dicarboxylic 
acids having the general formula I or II 
##STR2## 
where R.sup.1 is a chemical bond or a linear or branched alkyl chain 
having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 10 carbon 
atoms; R.sup.2 and R.sup.3 are an alkyl group having 1 to 4 carbon atoms, 
R.sup.4 is an alkyl group or an alkyl-substituted phenyl group having 1 to 
12 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms, and 
R.sup.5 is a cycloalkyl group having 3 to 12 carbon atoms. Examples of 
these are t-butylperoxy monovinyl esters, t-amylperoxy monovinyl esters, 
the cumylperoxy monovinyl esters and the pinylperoxy monovinyl esters of 
oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, 
pimelic acid, suberic acid, azelaic acid and sebacic acid. 
Preference is given to compounds of the formula I in which R.sup.1 is 
(CH.sub.2).sub.n where n=1 to 4 and n=8, R.sup.2 and R.sup.4 are a methyl 
group, and R.sup.3 is a methyl, ethyl or phenyl group; these compounds are 
the t-butylperoxy monovinyl esters, the t-amylperoxy monovinyl esters and 
the cumylperoxy monovinyl esters of malonic acid, succinic acid, glutaric 
acid, adipic acid and sebacic acid. 
Particular preference is given to compounds of the formula I in which 
R.sup.1 is (CH.sub.2).sub.n where n is 2 to 4 and n=8, and R.sup.2, 
R.sup.3 and R.sup.4 are a methyl group; these compounds are the 
t-butylperoxy monovinyl esters of succinic acid, glutaric acid, adipic 
acid and sebacic acid. Greatest preference is given to t-butylperoxy 
monovinyl adipate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The peroxy monovinyl dicarboxylates according to the invention are 
preferably prepared starting from the corresponding monovinyl 
dicarboxylates of the general formula H.sub.2 C.dbd.CH--O--CO--R.sup.1 
--COOH by esterification of the free acid group by means of the 
corresponding alkyl hydroperoxide of the general formula CR.sup.2 R.sup.3 
R.sup.4 --OOH or R.sup.5 .dbd.CR.sup.4 --OOH, where the radicals R.sup.1, 
R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined above. Synthetic 
routes starting from the corresponding monovinyl dicarboxylic anhydrides 
or dicarboxylic acid halides are also conceivable. 
In a particularly preferred embodiment, the esterification is carried out 
in the presence of dicyclohexylcarbodiimide (DCCD), the alkyl 
hydroperoxide and DCCD each being employed in a molar ratio of from 1:1 to 
1:2, in each case based on the monovinyl dicarboxylate. In the most 
preferred embodiment, the monovinyl dicarboxylate, the alkyl hydroperoxide 
and the dicyclohexylcarbodiimide are employed in approximately equimolar 
ratios and reacted with one another at a temperature of from 0.degree. to 
40.degree. C., if desired in the presence of an inert solvent such as 
diethyl ether. 
The olefinically unsaturated peroxy compounds according to the invention 
are suitable for the preparation of copolymers which contain peroxide 
groups and behave as "macroinitiators" in the block or graft 
copolymerization. The free peroxide groups in the copolymer function as 
anchor groups in the graft copolymerization and thus improve the phase 
binding of incompatible polymer phases, for example in core/shell latices. 
However, the reaction conditions in the copolymerization for the 
preparation of the peroxide-containing copolymers must be selected so that 
the peroxide bond is not broken. 
The invention furthermore relates to copolymers which contain the peroxy 
monovinyl esters of the formula I or II and to processes for their 
preparation. The peroxide group-containing copolymers contain between 0.01 
and 20% by weight of the olefinically unsaturated peroxy compound 
according to the invention and from 80 to 99.9% by weight of one or more 
comonomers from the group consisting of the (meth)acrylates of alcohols 
having 1 to 10 carbon atoms, vinyl esters of saturated aliphatic 
carboxylic acids having 2 to 10 carbon atoms, olefins, vinylaromatic 
compounds, vinyl halides and/or vinyl ethers, the data in % by weight in 
each case being based on the total weight of the copolymer. The content of 
peroxy compound is preferably from 0.01 to 10% by weight. particularly 
preferably between 0.01 and 5% by weight. 
Preferred base monomers are selected from the group consisting of the 
methacrylates or acrylates of alcohols having 1 to 10 carbon atoms, methyl 
methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, 
isopropyl methacrylate, isopropyl acrylate, tert.-butyl acrylate, n-butyl 
acrylate and ethylhexyl acrylate; from the group consisting of the vinyl 
esters of saturated aliphatic carboxylic acids having 2 to 10 carbon 
atoms, vinyl acetate, isopropenyl acetate, vinyl proprionate, vinyl 
laurate and vinyl esters of versatic.sup.R acid having 9 to 10 carbon 
atoms (vinyl esters of saturated .alpha.-branched monocarboxylic acids, 
commercial product from Shell); from the group consisting of the olefins, 
ethylene, propylene and 1,3-butadiene; from the group consisting of the 
vinyl halides, vinyl chloride, and styrene as the preferred vinylaromatic 
compound. 
If desired, the copolymers according to the invention may also contain, as 
base monomers, up to 10% by weight, based on the copolymer, of 
ethylenically unsaturated, functional comonomers. Examples of these are 
mono- or dicarboxylic acids such as methacrylic acid, acrylic acid or 
fumaric acid, and amides thereof; hydroxyl-functional monomers such as 
hydroxyethyl acrylate, 2-hydroxypropyl acrylate or N-methylolacrylamide; 
sulpoonate-functional monomers such as vinyl sulphonate or 
2-acrylamido-2-methylpropane sulphonate, and polyunsaturated monomers such 
as divinyl adipate. 
Particular preference is given to copolymers containing one or more 
comonomers from the group consisting of vinyl acetate, isopropenyl 
acetate, vinyl propionate, vinyl laurate, vinyl chloride and/or ethylene, 
and one or more olefinically unsaturated peroxy compounds selected from 
the group consisting of the t-butylperoxy, t-amyl-peroxy and cumylperoxy 
monovinyl esters of malonic acid, succinic acid, glutaric acid and/or 
adipic acid. Greatest preference is given to copolymers containing from 0 
to 50% by weight of ethylene, from 50 to 100% by weight of vinyl acetate 
and from 0.01 to 5% by weight of t-butylperoxy monovinyl adipate, the data 
in % by weight being based on the total weight of the copolymer and adding 
up to 100% by weight. 
The peroxy group-containing copolymers are prepared by free-radical 
polymerization in bulk, in solution, in suspension or in emulsion. Of said 
processes, emulsion polymerization is the preferred variant. The 
polymerization can be carried out batchwise or continuously, with or 
without use of seed latices, with initial introduction of all or some 
constituents of the reaction mixture or with partial initial introduction 
and subsequent metering in of the or some constituents of the reaction 
mixture, or by the metering process without any initial introduction. All 
meterings are preferably carried out at the rate of consumption of the 
respective components. 
The polymerization is initiated by free-radical formers in a temperature 
range of from 0.degree. to 80.degree. C., since significant decomposition 
if the peroxy groups in the copolymer occurs at higher temperature. The 
polymerization is preferably carried out at temperatures up to 70.degree. 
C. 
In the case of the preferred emulsion polymerization, the initiation is 
effected by means of water-soluble free-radical formers, which are 
preferably employed in amounts of from 0.01 to 3.0% by weight, based on 
the total weight of the monomers. Examples of these are ammonium and 
potassium persulphate and peroxodisulphate; hydrogen peroxide; and azo 
compounds such as azobisisobutyronitrile or azobiscyanovaleric acid. If 
the water-soluble free-radical former has a greater oxidation potential 
than the copolymerizable peroxide of the formula (I) or (II), for example 
in the case of t-butylhydroperoxide, potassium peroxodisulphate, sodium 
peroxodisulphate and ammonium peroxodisulphate, the formation of free 
radicals can be accelerated at lower temperatures with the aid of reducing 
agents. 
Dispersants which can be employed are all emulsifiers and protective 
colloids usually used in emulsion polymerization. From 1 to 6% by weight, 
based on the total weight of the monomers, of emulsifier are preferably 
employed. Examples of suitable compounds are anionic tensides such as 
alkyl sulphates having a chain length of from 8 to 18 carbon atoms; alkyl 
and alkylaryl ether sulphates having 8 to 18 carbon atoms in the 
hydrophobic radical and up to 40 ethylene oxide or propylene oxide units; 
alkyl or alkylaryl sulphonates having 8 to 18 carbon atoms and esters and 
monoesters of sulphosuccinic acid with monohydric alcohols or 
alkylphenols. Examples of suitable non-ionic tensides are alkyl polyglycol 
ethers or alkylaryl polyglycol ethers having 8 to 40 ethylene oxide units. 
If desired, protective colloids may be employed, preferably in amounts of 
up to 15% by weight, based on the total weight of the monomers. Examples 
of these are vinyl alcohol-vinyl acetate copolymers containing from 80% to 
100 mol % of vinyl alcohol units, polyvinylpyrrolidones having a molecular 
weight of from 5000 to 400,000, and hydroxyethylcelluloses having a degree 
of substitution in the range of from 1.5 to 3. 
The pH range desired for the polymerization, which is generally between 2.5 
and 10, preferably between 3 and 8, may be established in a known manner 
by acids, bases or conventional buffer salts such as alkali metal 
phosphates or alkali metal carbonates. In order to adjust the molecular 
weight, the regulators usually used, for example mercaptans, aldehydes and 
chlorinated hydrocarbons, can be added during the polymerization. 
The peroxide-containing copolymers are suitable as the graft base for the 
preparation of graft copolymers, block copolymers and core/shell 
dispersion particles having improved phase binding between the polymer 
phases. 
The invention furthermore relates to graft copolymers prepared from 
a) a grafted-on polymer phase containing one or more monomers from the 
group consisting of (meth) acrylates of alcohols having 1 to 10 carbon 
atoms, vinyl esters of saturated aliphatic carboxylic acids having 2 to 10 
carbon atoms, olefins, vinyl halides, styrene and styrene derivatives, and 
b) a peroxy group-containing copolymer phase containing from 0.01 to 20% by 
weight of the olefinically unsaturated peroxy compound according to the 
invention and from 80 to 99.9% by weight of one or more comonomers from 
the group consisting of the (meth)acrylates of alcohols having 1 to 10 
carbon atoms, vinyl esters of saturated aliphatic carboxylic acid having 2 
to 10 carbon atoms, olefins, vinylaromatic compounds, vinyl halides and/or 
vinyl ethers. 
Preferred monomers of the graft monomer phase from the group consisting of 
(meth)acrylates of alcohols having 1 to 10 carbon atoms are methyl 
methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, 
isopropyl methacrylate, isopropyl acrylate, t-butyl acrylate, n-butyl 
acrylate and ethylhexyl acrylate. Preferred vinyl esters of saturated 
aliphatic carboxylic acids having 2 to 10 carbon atoms are vinyl acetate, 
vinyl propionate and vinyl laurate. Preferred olefins are ethylene and 
propylene. The preferred vinyl halide employed is vinyl chloride. 
Particular preference is given to styrene and methyl methacrylate. In 
addition, the graft monomer phase may, if desired, also contain up to 10% 
by weight, based on the graft monomer phase, of the above-mentioned 
ethylenically unsaturated, functional comonomers. 
Preferred graft copolymers are those prepared from a graft base containing 
one or more comonomers from the group consisting of vinyl acetate, 
isopropenyl acetate, vinyl propionate, vinyl laurate, vinyl chloride 
and/or ethylene and containing from 0.01 to 10% by weight of one or more 
olefinically unsaturated peroxy compounds from the group consisting of 
t-butylperoxy, t-amylperoxy and cumylperoxy monovinyl esters of malonic 
acid, succinic acid, glutaric acid and/or adipic acid, and a grafted-on 
polymer phase made from (meth)acrylates of alcohols having 1 to 10 carbon 
atoms, vinyl esters of saturated aliphatic carboxylic acids having 2 to 10 
carbon atoms, vinyl halides, styrene and/or styrene derivatives. 
Particular preference is given to graft copolymers prepared from a graft 
base containing from 0 to 50% by weight of ethylene, from 50 to 100% by 
weight of vinyl acetate and from 0.01 to 5% by weight of t-butylperoxy 
monovinyl adipate, and a grafted-on polymer phase containing styrene or 
methyl methacrylate. 
The grafting can be carried out in bulk, solution, suspension or emulsion. 
It is preferably carried out by the emulsion polymerization process. For 
the graft copolymerization, the peroxide-containing copolymer is initially 
introduced, preferably in the form of a seed latex. The graft monomer 
phase can be initially introduced or metered in, for example as a 
preemulsion. The amount of graft monomer added is adjusted so that between 
1 and 99% by weight of these monomer units are present in the finished 
graft product. 
The graft copolymerization is carried out at temperatures 
.gtoreq.80.degree. C., preferably .gtoreq.90.degree. C., without further 
addition of initiators, since the peroxide-containing copolymers, as 
macroinitiators, initiate the graft reaction. The graft copolymerization 
is preferably carried out with addition of from 0.1 to 5.0% by weight of 
emulsifier, based on the total weight of the graft copolymer. 
The graft copolymer latex can be further worked up, for example by spray 
drying, roller drying or by coagulation with subsequent drying. 
The graft copolymer latices are suitable for use as binders in the textiles 
sector (nonwovens), as heat stable binders, for example in coatings for 
roof sheeting, as adhesives in plasters and as binders in emulsion paints. 
Graft copolymer resins obtained by coagulation or spray drying are 
suitable as impact modifiers in plastics, as phase promoters in polymer 
blends, as low profile additives in UP resins and for use as thermoplastic 
elastomers. 
The examples below serve to illustrate the invention in greater detail: 
EXAMPLE 1 
6.1 g (29.56 mmol) of dicyclohexylcarbodiimide were dissolved in 14 ml of 
diethyl ether in a 250 ml flask fitted with magnetic stirrer, dropping 
funnel and internal thermometer. 5.0 g (29.04 mmol) of monovinyl adipate 
were dissolved in 30 ml of diethyl ether and added slowly with vigorous 
stirring. After only a short time, a white, flocculant precipitate had 
formed. As soon as the addition of monovinyl adipate was complete, the 
mixture was cooled to below 5.degree. C., and the resultant precipitate 
was dissolved by addition of 20 ml of dichloromethane. 4.4 g (29.04 mmol) 
of t-butyl hydroperoxide were then slowly added dropwise, and the batch 
was subsequently stirred for 5 hours at temperatures below 5.degree. C. 
and left to stand overnight at low temperature. For work-up, the mixture 
was filtered through a suction filter. The residue was washed with a 
little dichloromethane, and the resultant clear solution was evaporated on 
a rotary evaporator, giving a clear liquid which decomposes at 
temperatures above 60.degree. C. 
.sup.1 H-NMR (CDCl.sub.3): 1.320 ppm, s, 9H; 1.705 ppm, m, 4H; 2.394 ppm, 
m, 4H; 4.574 ppm, m, 1H; 4.877 ppm, m, 1H; 7.200 ppm, m, 1H. 
EXAMPLE 2 
Analogously to Example 1, 6.1 g (29.56 mmol) of dicyclohexylcarbodiimide 
were dissolved in 14 ml of diethyl ether in a 250 ml flask. 6.66 g (29.04 
mmol) of monovinyl sebacate were dissolved in about 30 ml of diethyl ether 
and slowly added dropwise with vigorous stirring. The reaction was carried 
out precisely by the method described in Example 1 , giving a clear liquid 
which solidifies at temperatures below 0.degree. C. and decomposes above 
60.degree. C. 
.sup.1 H-NMR (CDCl.sub.3): 1.1-1.4 ppm, m, 17H, 1.51-1.73 ppm, m 4H, 
2.36-2.51 ppm, m, 4H, 4.573 ppm, m, 1H, 4.879 ppm, m, 1H, 7.15-7.3 ppm, m, 
1H. 
EXAMPLE 3 
Analogously to Example 1, 6.1 g (29.56 mmol) of dicyclohexylcarbodiimide 
were dissolved in 14 ml of diethyl ether in a 250 ml flask. 4.62 g (29.04 
mmol) of monovinyl glutarate were dissolved in about 30 ml of diethyl 
ether and slowly added dropwise with vigorous stirring. The reaction was 
carried out precisely by the method described in Example 1, giving a clear 
liquid which decomposes at temperatures above 60.degree. C. 
.sup.1 H-NMR (CDCl.sub.3): 1.32 ppm, s, 9H, 1.95-2.07 ppm, m, 2H, 2.43-2.56 
ppm, m, 4H, 4.571 ppm, m, 1H, 4.875 ppm, m, 1H, 7.15-7.3 ppm, m, 1H. 
EXAMPLE 4 
First, four solutions were prepared: 1. Initiator solution: 0.45 part by 
weight of potassium persulphate was dissolved in 14.6 parts by weight of 
water. 2. Monomers: 0.4 part by weight of divinyl adipate was dissolved in 
84.9 parts by weight of vinyl acetate. 3. Preemulsion: 0.8 part by weight 
of Na 2-acrylamido-2-methylpropanesulphonate and 2.2 parts by weight of a 
diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) were emulsified in 
40 parts by weight of water. 4. Peroxide solution: 1.95 parts by weight of 
t-butylperoxy monovinyl adipate (Example 1) were dissolved in 1.95 parts 
by weight of vinyl acetate. 
9.75 parts by weight of vinyl acetate, 0.05 part by weight of divinyl 
adipate, 0.25 part by weight of vinyl sulphonate, 0.515 part by weight of 
diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) and 0.125 part by 
weight of potassium persulphate were introduced into 87 parts by weight of 
water in a stirred autoclave, the mixture was warmed to 70.degree. C., and 
the autoclave was charged with 80 bar of ethylene. When the temperature 
equilibrium had been reached, the above-described solutions 1 to 3 were 
metered in. The metering rates were selected to correspond to a metering 
time of 5 hours in the case of the monomers (2) and a metering time of 6 
hours in the case of the initiator (1) and the preemulsion (3). When the 
metering of the monomers (2) was complete, the peroxide solution (4) was 
metered in over the course of one hour. 
A finely dispersed dispersion having a solids content of 46% by weight and 
a monomodal particle size distribution, with the mean particle size being 
168 nm, resulted. The copolymer had an ethylene content of 41% by weight 
and an active oxygen content of 0.085%. The glass transition temperature 
of the polymer resin (DSC) was -21.degree. C., and its K value (measured 
in tetrahydrofuran, THF) was 40.1. 
EXAMPLE 5 
The procedure was analogous to Example 4, with the difference that 
t-butylperoxy monovinyl adipate was metered in together with the vinyl 
acetate phase over the entire reaction time. To this end, three solutions 
were prepared: 1. Initiator solution: 0.45 part by weight of potassium 
persulphate was dissolved in 14.6 parts by weight of water. 2. Monomers: 
0.4 part by weight of divinyl adipate and 1.95 parts by weight of 
t-butylperoxy monovinyl adipate (Example 1) were dissolved in 86.8 parts 
by weight of vinyl acetate. 3. Preemulsion: 0.8 part by weight of Na 
2-acrylamido-2-methylpropane-sulphonate and 2.2 parts by weight of a 
diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) were emulsified in 
40 parts by weight of water. 
9.75 parts by weight of vinyl acetate, 0.05 part by weight of divinyl 
adipate, 0.25 part by weight of vinyl sulphonate, 0.515 part by weight of 
a diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) and 0.125 part 
by weight of potassium persulphate were introduced into 87 parts by weight 
of water in a stirred autoclave, the mixture was warmed to 70.degree. C., 
and the autoclave was charged with 80 bar of ethylene. When the 
temperature equilibrium had been reached, the above-described solutions 1 
to 3 were metered in. The metering rates were selected to correspond to a 
metering time of 6 hours. 
A finely dispersed dispersion having a solids content of 47.6% by weight 
and a monomodal particle size distribution, with the mean particle size 
being 179 nm, resulted. The copolymer had an ethylene content of 31% by 
weight and an active oxygen content of 0.226%. The glass transition 
temperature of the polymer resin (DSC) was -16.degree. C., and its K value 
(measured in tetrahydrofuran, THF) was 40.3. 
EXAMPLE 6 
For the graft polymerization, 10 parts by weight of the peroxide 
group-containing copolymer from Example 4 in the form of a 6% strength 
aqueous dispersion were introduced into a polymerization reactor together 
with 0.005 part by weight of iron(II) ammoniumsulphate, the mixture was 
heated to 90.degree. C., and a preemulsion comprising 89.55 parts by 
weight of styrene, 0.45 part by weight of acrylic acid and 2 parts by 
weight of Aerosol MA in 45 parts by weight of water was metered in with 
stirring over a period of 2 hours. When the metering was complete, the 
graft polymerization was completed at 93.degree. C., giving a 39.5% 
strength polymer dispersion having a residual monomer content of 1.3% by 
weight and a mean particle size of 330 nm with a narrow, monomodal 
particle size distribution. The K value of the resin was 65.1, and the 
insoluble content in ethyl acetate was 29.7% by weight. 
EXAMPLE 7 
The procedure was analogous to Example 6, with the difference that 20 parts 
by weight of the peroxide group-containing copolymer from Example 5 were 
initially introduced in the form of an 11% strength aqueous dispersion, 
and 79.6 parts by weight of styrene, 0.4 part by weight of acrylic acid 
and 1.4 parts by weight of Aerosol MA in 40 parts by weight of water were 
metered in, giving a 42.6% strength polymer dispersion having a residual 
monomer content of 0.78% by weight and a mean particle size of 289 nm with 
a narrow, monomodal particle size distribution. The K value of the polymer 
resin was 61.1, and the insoluble content in ethyl acetate was 27.8% by 
weight. 
EXAMPLE 8 
The procedure was analogous to Example 6, with the difference that 90 parts 
by weight of the peroxide group-containing copolymer from Example 3 were 
initially introduced in the form of a 36% strength aqueous dispersion, and 
9.95 parts by weight of styrene, 0.05 part by weight of acrylic acid and 
0.1 part by weight of Aerosol MA in 5 parts by weight of water were 
metered in, giving a 43% strength polymer dispersion having a residual 
monomer content of 0.26% by weight and a mean particle size of 195 nm with 
a narrow, monomodal particle size distribution. The K value of the resin 
was 42.1. 
COMATIVE EXAMPLE 1 
A copolymer was prepared analogously to Example 5, but no 
t-butylperoxymonovinyl adipate was copolymerized. To this end, three 
solutions were prepared: 1. Initiator solution: 0.45 part by weight of 
potassium persulphate was dissolved in 14.6 parts by weight of water. 2. 
Monomers: 0.4 part by weight of divinyl adipate was dissolved in 88.8 
parts by weight of vinyl acetate. 3. Preemulsion: 0.8 part by weight of Na 
2-acrylamido-2-methylpropanesulphonate and 2.2 parts by weight of a 
diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) were emulsified in 
40 parts by weight of water. 
9.75 parts by weight of vinyl acetate, 0.05 part by weight of divinyl 
adipate, 0.25 part by weight of vinyl sulphonate, 0.515 part by weight of 
a diisohexylsulphosuccinate (Aerosol MA 80 from Cyanamid) and 0.125 part 
by weight of potassium persulphate were introduced into 87 parts by weight 
of water in a stirred autoclave, the mixture was warmed to 70.degree. C., 
and the autoclave was charged with 80 bar of ethylene. When the 
temperature equilibrium had been reached, the above-described solutions 1 
to 3 were metered in. The metering rates were selected to correspond to a 
metering time of 6 hours. 
A finely dispersed dispersion having a solids content of 43% by weight and 
a monomodal particle size distribution, the mean particle size being 178 
nm, resulted. The copolymer had an ethylene content of 36% by weight and 
an active oxygen content of 0%. The glass transition temperature of the 
polymer resin (DSC) was -25.4.degree. C., and its K value (measured in 
tetrahydrofuran, THF) was 39.4. 
COMATIVE EXAMPLE 2 
The procedure was analogous to Example 6, but the graft base initially 
introduced comprised 10 parts by weight of the copolymer from Comparative 
Example 1 in the form of a 6% strength dispersion. In order to initiate 
the graft reaction, an amount of initiator which was equivalent to the 
peroxide groups of the copolymer from Example 4, namely 0.516 part by 
weight of t-butylperoxy pivalate and 0.174 part by weight of t-butylperoxy 
2-ethylhexanoate, was metered into the preemulsion together with 89.55 
parts by weight of styrene, 0.45 part by weight of acrylic acid and 2.0 
parts by weight of Aerosol MA in 40 parts by weight of water, giving a 
41.8% strength polymer dispersion having a residual monomer content of 
0.78% by weight and a mean particle size of 368 nm with a broad monomodal 
particle size distribution. The K value of the polymer resin was 50.2, and 
the insoluble content in ethyl acetate was 2.5% by weight. 
COMATIVE EXAMPLE 3 
The procedure was analogous to Example 7, but the graft base initially 
introduced comprised 20 parts by weight of the copolymer from Comparative 
Example 1 in the form of a 12% strength dispersion. In order to initiate 
the graft reaction, an amount of initiator which was equivalent to the 
peroxide groups of the copolymer from Example 5, namely 0.516 part by 
weight of t-butylperoxy pivalate and 0.174 part by weight of t-butylperoxy 
2-ethylhexanoate, was metered into the preemulsion together with 79.6 
parts by weight of styrene, 0.40 part by weight of acrylic acid and 1.40 
parts by weight of Aerosol MA in 30 parts by weight of water, giving a 
44.0% strength polymer dispersion having a residual monomer content of 
0.57% by weight and a mean particle size of 310 nm with a narrow, 
monomodal particle size distribution. The K value of the polymer resin was 
51.6, and the insoluble content in ethyl acetate was 8.8% by weight. 
It is clear from Examples 6 and 7 and Comparative Examples 2 and 3 that the 
molecular weight (see K value) of the graft polymers in the case of 
grafting onto the peroxide-containing copolymers ("macroinitiators") was 
significantly increased. The ethyl acetate-insoluble content of the graft 
products is also significantly increased in the case of the 
peroxide-containing products and confirms the improved coupling of the 
polystyrene phase to the EVAc phase.