WO1997042017A1

WO1997042017A1 - Process for producing dip-coated articles

Info

Publication number: WO1997042017A1
Application number: PCT/EP1997/002096
Authority: WO
Inventors: Peter Claassen; Onno Graalmann; Wolfgang Alois Hormuth; Klaus Joachim MÜLLER-ENGEL
Original assignee: Basf Aktiengesellschaft
Priority date: 1996-05-04
Filing date: 1997-04-24
Publication date: 1997-11-13
Also published as: AU2769997A; ID17625A; NO985119L; CN1211210A; DE19618006A1; EP0904184A1; JP2000509421A; CA2253909A1; NO985119D0; KR20000010757A; BR9709136A; MX9806234A

Abstract

A process for producing dip-coated articles in which a heated moulding with an electrolyte adsorbing surface is dipped into an aqueous latex preparation, the latex of which is stabilised substantially by emulsifiers with anionic sulphonate groups and is heat-sensitised by a silicon-organic tenside having non-ionic polyether groups and a cloud temperature in the range from 30 to 40 °C.

Description

Process for the manufacture of diving articles

description

The present invention relates to a process for the production of immersion articles, in which a molded body is immersed in an aqueous latex immersion preparation in order to form a continuous polymer film on the surface of the molded body.

Aqueous latices (aqueous polymer dispersions) are generally known. These are fluid systems which contain, as a disperse phase in an aqueous dispersion medium, polymer balls consisting of a plurality of intertwined polymer chains (so-called polymer particles) in a disperse distribution.

In contrast to polymer solutions, latices do not form thermodynamically stable systems. Rather, the system tries to reduce the polymer / dispersing medium interface by combining small primary particles to form larger secondary particles, which in the state of disperse distribution in the aqueous medium is achieved by adding dispersants (substances which increase the "dispersed polymer / aqueous dispersing medium" interface) stabilize assets) can be prevented for a long time.

This means that aqueous polymer dispersions have the potential to form a coherent polymer matrix when the dispersant is deactivated in a controlled manner by partially or completely fusing the dispersed polymer particles.

While a chemical linkage of different polymer chains within the polymer particles generally proves to be disadvantageous with regard to the formation of the aforementioned polymer matrix, after the polymer matrix has been formed a subsequent chemical linkage (crosslinking) of the polymer chains constituting it is necessary to adjust mechanical properties (e.g. elasticity) often desired.

The aforementioned relationships are known and are used for the production of immersion articles from aqueous polymer dispersions which, by means of free-radical aqueous emulsion polymerization of a mixture of at least one ethylenically unsaturated group, have monomers which comprise at least 30% of its weight two conjugated monomers containing ethylenically unsaturated double bonds are available.

If such a radical aqueous emulsion polymerization 5 takes place at temperatures which are not too high and, if appropriate, with the use of substances which regulate the molecular weight, such as mercaptans (for example tert-dodecyl mercaptan or n-dodecyl mercaptan), only one of the two conjugated ethylenically takes substantially unsaturated double bonds 10 in the polymerization reaction.

This gives aqueous polymer dispersions whose dispersed polymer balls consist of polymer chains which, on the one hand, are essentially uncrosslinked (i.e. not to one another

15 are chemically bonded), but on the other hand still have ethylenically unsaturated double bonds which, after the desired polymer matrix has been formed, by vulcanization systems based on sulfur which are suitable in a known manner and which, if appropriate in addition to other auxiliaries, are usually customary

20 before formation of the polymer matrix into the aqueous polymer dispersion to obtain aqueous latex preparations (hereinafter referred to as aqueous latex dipping preparations), activated in association with elevated temperature and targeted to form a reaction with the formation of intramolecular crosslinking

25 can be brought, whereby a degree of crosslinking desired in terms of application technology can be set.

Typical aqueous latex dipping preparations contain (see e.g. rubber handbook, volume 4, Berlin Union Verlag, Stuttgart, 30 1961, p. 247):

35

40

The use of vulcanization accelerators is necessary because of the inertness of the sulfur and the second olefinically unsaturated group of the polymerized conjugated diene. The most important accelerators are thiazoles (also called mercapto accelerators) like 2-mercaptobenzothiazole, whose Zinc salt and dibenzothiazyl disulfide, sulfenamides such as benzothiazyl-2-cyclohexylsulfenamide, benzothiazyl -2-tert. -butylsulfen- amide, benzothiazyl-2 -sulfenmorpholid and benzothiazyl-dicyclo-hexylsulfenamide, guanidines such as diphenylguanidine, di-orthotolyl-guanidine and ortho-tolylbiguanidine, thiurams such as tetramethyl, thiuram disulfide and zinc tetramethylthiamidithiamidithiamidithiamidithiamidithi, such as tetramethyldithamidithiamidithiamidithi, such as tetramethyldimidate and tetraulfidylamidithi N-diethyl dithiocarbamate, zinc-N-dibutyl dithiocarbamate, zinc N-ethylphenyldithiocarbamat and zinc N-pentamethylendithiocarbamat, Thiolenstoffe lenthioharnstoff as ethylene, cloth and Diethylenthioharnstoff Diphenylthioharn- and aldehyde-amine condensation products such as those of butyraldehyde and aniline. Mixtures of vulcanization accelerators are often used.

In order to develop their optimal effectiveness, the vulcanization accelerators normally require the addition of zinc oxide as an activator.

The unsaturated groups still present in the latex dipping preparation, which on the one hand enable vulcanization due to their reactivity with sulfur, on the other hand cause sensitivity to reactive influences such as 0 ₂ or UV radiation. As a consequence of this interaction, the latex can harden and become brittle (age). Bacterial attack on the organic polymer is an additional source of aging. In order to counteract these effects, anti-aging agents such as Wingstay L are normally added to the latex dipping preparation. By adding fillers and / or plasticizers, the physical property profile of the diving article can be influenced.

In the immersion process, a shaped body is now immersed in the aqueous latex immersion preparation and a coherent polymer film is deposited on the surface of the shaped body as a polymer matrix by controlled coagulation. The molded body is then removed from the aqueous latex dipping preparation, dried, the polymer film enveloping the molded body is vulcanized by the action of heat, and then the vulcanized diving article (for example suction cups, condoms, medical gloves, surgical gloves, industrial gloves, housewife gloves, fingers, balloons or special goods for medical purposes) is stripped from the molded body and optionally washed, dried and optionally powdered or chlorinated. In order to carry out controlled coagulation on the surface of the solid, two different principles are implemented in the prior art:

a) electrolyte coagulation

and

b) thermocoagulation.

An aqueous latex dipping preparation is used for the electrolyte coagulation, the aqueous latex of which is mainly stabilized with regard to its disperse distribution by suitable anionic emulsifiers.

In this document, surfactants are referred to as emulsifiers whose relative molecular weight is <1000 and which, when dissolved in water (at 25 ° C. and 1 atm) until a critical micelle formation concentration is reached, the surface tension α of the water by at least 25% (based on the Surface tension of pure water) can decrease (from lat. Tensio = tension). In contrast, the term surfactant here simply means an amphiphilic substance that, when dissolved in water (at 25 ° C and 1 atm), can reduce the surface tension of the pure water. The term amphiphilic means that surfactants have both hydrophilic and hydrophobic groups. Anionic emulsifiers are those in which the hydrophilic groups in the aqueous medium carrying a negative charge, face wherein these hydrophilic groups small, the boundary surface-active properties of the anionic emulsifier ion little be ^¬ inflow end monovalent cations such as alkali metal or ammonium.

Oriented adsorption of the anionic emulsifier on the essentially non-polar surface of the dispersed polymer particles gives polymer particles which have a negative surface charge and whose mutual charge repulsion stabilizes their disperse distribution.

In contrast, nonionic emulsifiers have no ionic charge in the aqueous medium. The hydrophilicity of their hydrophilic grouping is generally determined by the polarity of an increased number of covalently bound oxygen atoms.

The principle of electrolyte coagulation is based on the fact that a molded body is immersed in the aqueous latex dipping preparation, the surface of which is an electrolyte (sub- punch, which dissociates in the presence of water in anion and cation), the cation of which interacts with the anionic emulsifier group in such a way that its stabilizing effect is reduced in a controlled manner and the desired coagulation is triggered.

While an aqueous latex immersion preparation which is sensitive to the addition of electrolyte is used for the electrolyte coagulation, an aqueous latex immersion preparation which is sensitive to an increase in temperature is required for the thermocoagulation. For this purpose, coagulants are added to the aqueous latex dipping preparation which only become effective above a certain temperature, the coagulation temperature. If one immerses a shaped body having an elevated temperature in such a heat-sensitized aqueous latex immersion preparation, coagulation occurs on its surface which continues until the surface temperature of the shaped body is permanently below the set coagulation temperature of the aqueous latex immersion preparation.

The production of diving articles based on pure thermo-coagulation is described in the prior art (Kautschuk- Handbuch, Volume 4, Berlin Union Verlag, Stuttgart, 1961, pp. 252 to 256; High Polymer Latices, DC Blackley, Vol. 2, Maclaren & Sons Ltd., London, 1966, p. 532; DE-AS 1243394; DE-A 1494037; Ulimann's Encyclopedia of Industrial Chemistry, Verlag Chemie, Weinheim, Vol. 13, Hormone bis Keramik, 1977, p. 676; Bayer - Messages for the rubber industry, vol. 32, year 63, pp. 56 to 69;).

It is advantageous in that, when immersed, high thicknesses of the deposited polymer matrix can be achieved in a relatively short time.

A disadvantage of the above-mentioned procedure is that moldings with a very narrow range of uniform heat capacity and temperature are required for uniform thicknesses of the immersion article. Furthermore, particularly high removal speeds are necessary in order to achieve a uniform film thickness along the shaped body. Furthermore, the mechanical property profile of the resulting diving article is often not fully satisfactory.

The production of immersed articles on the basis of pure electrolyte coagulation is also described in the prior art (for example US-A 2 880189; EP-A 378380; EP-A 456333; Kautschuk-Handbuch, Volume 4, Berlin Union Verlag, Stuttgart , 1961, pp. 246 to 252; High Polymer Latices, DC Blackley, Vol.2, Maclaren & Sons Ltd., London, 1966, pp. 530-532; Ulimann's Encyclopedia of Technical Chemistry, Verlag Chemie, Weinheim, Vol. 13, Hormones bis Keramik, 1977, p. 676; Bayer press releases for the rubber industry, vol. 32, year 63, pp. 56 to 69;).

The advantages of producing diving articles on the way of electrolyte coagulation lie in the increased reproducibility of the diving article thickness and the favorable resulting mechanical property profile. A disadvantage is the increased immersion time required for a given film thickness, which is due to the fact that the coagulation electrolyte requires a certain time to diffuse through the gradually thicker film and to bring other parts of the aqueous latex immersion composition to coagulation .

In contrast, the object of the present invention was to provide a process for the production of immersion articles, in which a molded body is immersed in an aqueous latex immersion preparation, which has both the advantages of electrolyte coagulation and the advantages of thermocoagulation.

Accordingly, a process has been found for the production of diving articles in which, normally at a pressure of 1 atm, a molded body having a temperature T, the surface of which has an electrolyte adsorbed as a coagulant, is immersed in an aqueous latex dipping preparation which is an aqueous polymer dispersion, the monomers having at least 30% by weight of two conjugated ethylenically unsaturated monomers having double bonds have been obtained by the method of free radical aqueous emulsion polymerization and have, based on the weight of the dispersed polymer, monomers ,

added, with the proviso that the electrolyte adsorbed on the molded body surface is a Bronsted acid and / or a salt,

the free radical aqueous emulsion polymerization takes place in the presence of dispersants which consist of at least 50% by weight of water-soluble alkali metal and / or ammonium salts of the monosulfonic acids of Cχo to C ₂ o "hydrocarbons,

10 - the aqueous latex dipping preparation contains, as a thermal coagulant, a nonionic, polyether group-containing, organosilicon surfactant with a cloud point in the range from 20 to 60, preferably 30 to 40 ° C. and

15 - the temperature T is above the cloud point of the organosilicon surfactant. Suitably T is> 40 to <150 ° C. T is preferably 60 to 90 ° C.

The cloud point is the temperature at which the aqueous solution of the polyether-modified organosilicon compound, which is clear at 20 ° C., decomposes into two phases when the temperature rises (usually the cloud point is based on a 4% strength by weight aqueous solution of the surfactant ). The effect of the above-mentioned organosilicon surfactants according to the invention is presumably based on the fact that at low temperature they are able to dissolve in an aqueous medium with hydration. When the temperature rises, when the turbidity temperature is reached, there is obviously spontaneous dehydration with phase separation as a result of adduct binding with itself and the sulfonates used as emulsifiers, which results in the sudden latex coagulation.

In the simplest case, the polyether-modified nonionic silicon

35 organic surfactants (which are known and commercially available) for polyether-modified siloxanes containing hydrophobic groups, such as those e.g. are described in DE-AS 1243394, DE-AS 1794418 and DE-A 1494037. However, they also include such polyether-modified nonionic organosilicon

40 surfactants in which the polyether-modified organosilicon compound is grafted as a hydrophilic part onto the polymer of a conjugated diene, preferably 1,2-polybutadiene, as a hydrophobic part, as described e.g. in DE-A 3218676, DE-A 2321557 and DE-3718588 Cl are disclosed by way of example.

45 Suitable modifying polyether groups are homopolymers and copolymers of alkylene oxides such as ethylene oxide, propylene oxide or isobutylene oxide. Homopolymers of are preferred Ethylene oxide. As a rule, the number average relative molecular weight of the nonionic polyether-modified organosilicon surfactants to be used according to the invention is> 1000 and <50000. Preferred inventive use poly- ether-modified organosilicon surfactants are the commercial products Basensol ^® HA 5 (cloud point: 38 ° C) from BASF AG and Coagulant WS (cloud point: 32 ° C) of Bayer AG.

Based on the amount of dispersed polymer contained in the aqueous latex immersion preparation to be used according to the invention, the amount of polyether-modified organosilicon compound required according to the invention is generally 0.1 to 5% by weight.

Among the alkali metal and / or ammonium salts of the radi¬-earth aqueous emulsion according to the invention preferably the sodium salts to be used with Cio * to C ₂ o "are hydrocarbyl.

Examples include sodium dodecyl sulfonate, sodium myristyl sulfonate and sodium stearyl sulfonate as representatives of the sulfonates of aliphatic Cio to C ₂ o "hydrocarbons, and sodium Dodecylbenzenesulfonate as representatives of alkylaryl sulfonates. Of course, mixtures of such sulfonates of Cχo- to C ₂ " can also be used are how they are commercially available (eg Cicr, Cι ₂ - and Cι ₃ alkylbenzenesulfonate mixtures or C ₁₄ -, C ₁₅ -, Cι ₆ - and Cι ₇ alkane-sulfonate mixtures).

According to the invention for radical aqueous emulsion polymerization, based on the amount of the resulting dispersed emulsion polymer, usually 0.1 to 5% by weight, usually 0.5 to 2% by weight, of the water-soluble alkali metal and / or ammonium salts of the monosulfonic acids from Cio to C ₂ o-hydrocarbons used.

In addition to the invention according to the required alkali metal and / or ammonium salts of monosulfonic acids of CIO to C ₂ o-hydrocarbon ^¬ materials the total amount of dispersing agent used for the free radical aqueous emulsion may contain up to 50% of their weight contain other dispersants. Other anionic and / or nonionic emulsifiers and / or surfactants such as ethoxylated mono-, di- and tri-alkylphenols (EO degree: 3 to 100, alkyl radical: C ₄ to C ₂ ), ethoxylated fatty alcohols are suitable as such (EO grade: 3 to 100, alkyl radical: C _B to Cι ₈ ), alkali and ammonium salts of alkyl sulfates (alkyl radical: Ce to Ciβ), of sulfuric acid half-esters O 97/42017 PC17EP97 / 02096

9 with ethoxylated alkanols (EO degree: from 1 to 70, alkyl radical: Cι ₂ to Ciβ) of aryl and of alkylaryl sulfates (alkyl radical: C ₉ to Cι ₈₎ and of C ₈ - to Ciβ-fatty acids and disproportionier ^¬ th resin acids from Rosin (Dresinate). Protective colloids such as polyvinyl alcohols, cellulose derivatives, copolymers containing vinylpyrrolidone or polycondensates of naphthalenesulfonic acid and formaldehyde are of course also suitable as such further dispersants. In contrast to emulsifiers and surfactants, they are unable to form micelles in the aqueous polymerization medium and generally have relative molecular weights of> 1000. Furthermore, they hardly influence the surface tension of water. Suitable polycondensates of naphthalenesulfonic acid and formaldehyde (or their water-soluble salts) have, for example, a relative molecular weight of 4,000 to 8,000. A combination of emulsifiers and protective colloids will often be used when aqueous polymer dispersions whose dispersed polymer particles are chemically as uniform as possible are aimed at for monomers to be polymerized with markedly different water solubility. The diameter of the resulting emulsion polymer particles is usually determined via the absolute amount of emulsifier used. Its weight-average value is preferably 80 to 300, particularly preferably 100 to 250 and very particularly preferably 100 to 200 nm.

The amount of other dispersants (in addition to the sulfonates required according to the invention), based on their total amount, is advantageously not more than 25% or not more than 10% of their weight. Favorable embodiments according to the invention are those in which no further dispersants are used.

To prepare the aqueous polymer dispersion which forms the basis of the aqueous latex immersion preparation to be used according to the invention, the monomer mixture to be polymerized by the free-radical aqueous emulsion polymerization method can contain only two conjugated ethylenically unsaturated groups (monomers A), or else additionally from the monomers A include various comonomers having at least one ethylenically unsaturated group. The proportion of the monomers A in the monomer mixture to be polymerized according to the invention is frequently 30 to 90% by weight, often 40 to 70% by weight and in many cases 50 to 70% by weight. Examples of possible monomers A are butadiene, 2-methyl-butadiene, 2,3-dimethylbutadiene, pentadiene 1.3 or pentadiene 2.4 or mixtures of these monomers. Mono-ethylenically unsaturated comonomers which, at normal pressure (1 atm) and 25 ° C, have an increased molar water solubility (> that of Acrylonitrile) (monomers B), are usually contained in the monomer mixture to be polymerized in amounts of up to 10% by weight, often in amounts of 3 to 8% by weight. Customary monomers B are, for example, α, β-monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 6 carbon atoms, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, the salts of these carboxylic acids (in particular the alkali metal salts and the ammonium salt), the amides the abovementioned α, β-monoethylenically unsaturated carboxylic acids, such as, for example, acrylamide and methacrylamide, also vinylsulfonic acid and its water-soluble salts (in particular the alkali metal salts and the ammonium salt) and N-vinylpyrrolidone. The monomers B can of course also be used in a mixture. While butadiene is the preferred monomer A, methacrylic acid is the preferred monomer B.

The proportion of other copolymerizable monomers (monomers C) having an ethylenically unsaturated group can be up to 70% by weight. The proportion of the monomers C is frequently 10 to 70, often 30 to 60 and in many cases 30 to 50% by weight. Suitable monomers C are e.g. vinyl aromatic monomers such as styrene, vinyl toluene or o-chlorostyrene, acrylonitrile, methacrylonitrile and esters from acrylic or methacrylic acid with alkanols having 1 to 8 carbon atoms, and the mixtures of these monomers among which styrene, acrylonitrile and methyl methacrylate and mixtures thereof are particularly suitable Are monomers C.

That is, aqueous dispersions of free-radical aqueous emulsion polymers of monomer mixtures consisting of are suitable

30 to 100% by weight of monomers A,

0 to 10% by weight of monomers B and 0 to 70% by weight of monomers C.

These include radical aqueous emulsion polymers of monomer mixtures consisting of

30 to 100% by weight of at least one monomer from the group comprising butadiene, 2-methylbutadiene and 2, 3-dimethylbutadiene,

0 to 10% by weight of at least one monomer from the group comprising acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide and 0 to 70% by weight of at least one monomer from the group comprising styrene, acrylonitrile and methyl methacrylate.

These include, in particular, free-radical aqueous emulsion polymers of monomer mixtures consisting of

30 to 100% by weight of butadiene,

0 to 10% by weight of methacrylic acid and 0 to 70% by weight of acrylonitrile.

The abovementioned monomer mixture grids also result in suitable free-radical aqueous emulsion polymers if the proportions by weight of the combinations of monomers A, B and C mentioned are divided as follows:

30 to 90% by weight of monomers A,

1 to 10% by weight of monomers B and 9 to 60% by weight of monomers C.

or

40 to 80% by weight of monomers A, 1 to 10% by weight of monomers B and 19 to 50% by weight of monomers C.

or

45 to 70% by weight of monomers A 3 to 10% by weight of monomers B and 27 to 45% by weight of monomers C.

This is particularly true if the monomers A are only butadiene, the monomers B are only methacrylic acid and the monomers C are only acrylonitrile.

As already mentioned, to limit the degree of crosslinking, the free-radical aqueous emulsion polymerization is generally carried out in the presence of so-called molecular weight regulators (chain transfer agents), such as mercaptans (alkanethiols), which advantageously have 3 to 15 carbon atoms. Regularly are tert. -Dodecyl mercaptan and / or n-dodecyl mercaptan used as a molecular weight regulator. The free-radical aqueous emulsion polymerization is typically carried out in the presence of from 0.1 to 3% by weight, frequently from 0.5 to 1.5% by weight, based on the monomers to be polymerized, of such molecular weight regulators. Radical polymerization initiators which can be used to carry out the free radical aqueous emulsion polymerization are in principle all those which are capable of triggering a free radical aqueous emulsion polymerization. Both peroxides and azo compounds can be involved. To limit the degree of crosslinking of the resulting emulsion polymer, those initiator systems are preferred whose decomposition temperature is <55 ° C. In other words, preference is given to using combined systems which are composed of at least one reducing agent and at least one peroxide and / or hydroperoxide, since the reducing agents activate the formation of free radicals and thus enable the free-radical aqueous emulsion polymerization according to the invention to be started at low temperatures .

Suitable reducing agents are, for example, ascorbic acid, acetone bisulfite, the sodium salt of hydroxymethanesulfinic acid, sodium sulfite, sodium hydrogen sulfite or sodium dithionite. The aforementioned combined (redox initiator) systems very particularly preferably additionally comprise a small amount of a metal compound which is soluble in the polymerization medium and whose metallic component can occur in several valence stages.

An example of such metal compounds are iron (II) salts such as iron (II) sulfate. Instead of a water-soluble iron (II) salt, a combination of water-soluble Fe / V salts is often used. Such redox initiator systems containing such a metal compound are advantageous in that they enable the free-radical aqueous emulsion polymerization according to the invention to be started at even lower temperatures. Examples of such redox initiator systems are ascorbic acid / iron (II) sulfate / hydrogen peroxide or sodium dithionite and / or sodium formaldehyde sulfoxylate / iron (II) sulfate / para-menthane hydroperoxide or diisopropylbenzene hydroperoxide or cumene hydroperoxide. Often a small amount of a chelating agent is added to such redox initiator systems containing a metal compound in order to ensure that the metallic component is in solution and not e.g. is withdrawn by a precipitation reaction. The sodium salts of ethylenediaminetetraacetic acid may be mentioned as an example of such a chelating agent. The metallic component is often added directly as a chelate complex.

Based on the monomers to be polymerized, the amount of initiator to be used is generally from 0.01 to 5%, usually from 0.01 to 1% by weight. Normally, according to the invention Polymerized inert gas atmosphere. Sodium dithionite is also suitable as a scavenger for residual amounts of oxygen. Furthermore, pH buffers such as alkali metal phosphate can be added to stabilize the pH of the aqueous dispersing medium during the emulsion polymerization. The addition of small amounts of strong electrolytes such as potassium sulfate, potassium chloride and / or sodium sulfate makes it easier, in a manner known per se, to set the desired polymer particle diameter by means of a controlling influence in the polymer particle formation phase.

Generally speaking, the polymerization temperature, type and amount of molecular weight regulator and polymerization conversion are advantageously coordinated with one another in such a way that aqueous polymer dispersions result, the crosslinking density of which is such that the transverse nuclear magnetic relaxation time of the protons chemically bound to the polymer ( ^1H T ₂ ) 2, 5 to 4.5 ms. These values relate to a sample of the respective aqueous polymer dispersion, which was filmed at 25 ° C. and then dried for 2 hours at 80 ° C., at a sample temperature of 140 ° C. and a ^ resonance frequency of 20 MHz. The relationship between ^1H T ₂ and the crosslinking density is shown, for example, in Macromolecule 1994,27,2111-2119. It is ultimately based on the fact that the transversal nuclear magnetic relaxation time of an atomic nucleus having a magnetic moment is on the one hand a measure of its mobility in an external magnetic field and a crosslinking of different polymer chains limits its mobility on the other hand. The lower the mobility of a polymer chain, ie the greater the crosslinking density, the shorter the transverse nuclear magnetic relaxation time of atomic nuclei chemically bound to this polymer chain and having a magnetic moment.

The polymerization conversion of the free radical aqueous emulsion polymerization is stopped as required as a rule by adding polymerization inhibitors such as dimethylhydroxylamine and then unreacted monomers are removed in a manner known per se by deodorization (preferably stripping and / or steam distillation).

DE-A 19545096, for example, discloses the implementation of a free-radical aqueous emulsion polymerization as described above.

The radical aqueous emulsion polymerization can be carried out in the simplest manner by placing the total amount of the polymerization batch, namely part of the polymerization initiator, in the polymerization vessel. triggering the polymerization by heating to the polymerization temperature and, with the successive addition of the remaining radical polymerization initiator and maintaining the polymerization temperature, continuing the radical aqueous emulsion polymerization until the desired polymerization conversion. If monomers are polymerized in here, the residual monomers of which remain after the end of the free-radical aqueous emulsion polymerization (eg acrylonitrile) can be difficult to remove in the last polymerization stage, the relative proportion of relatively easily removable residual monomers (eg butadiene) ) by a separate addition.

Another possibility of realizing the free radical aqueous emulsion polymerization is the method of the continuous monomer feed process. Only a small part of the monomers to be polymerized is placed in the polymerization vessel, expediently polymerized in the presence of an added seed latex, and the remaining amount of the monomers to be polymerized is then fed continuously to the polymerization vessel in accordance with their consumption while maintaining the free radical aqueous emulsion polymerization.

As a rule, the aqueous polymer dispersions to be used according to the invention are produced with a solids volume fraction of 30 to 70% by volume, usually 40 to 50% by volume.

To prepare the aqueous latex dipping formulation to be used for the process according to the invention, the required vulcanization system, optionally further auxiliaries and the nonionic polyether-modified silicon-organic surfactant are usually incorporated into the aqueous polymer dispersion obtained by the free-radical aqueous emulsion polymerization method.

The thermal sensitizer is expediently incorporated last. The remaining substances to be incorporated are essentially solids which must be incorporated in the finest possible form in order to develop their effect. Powdery substances generally have a high from ^¬ sorption capacity for water and therefore can be in trok- kenem state with difficulty in aqueous polymerizate dispersions incorporated as they escape the latex serum, thereby causing partial coagulation. Other finely divided solids act without having a particularly high absorption capacity, coagulating in that they have a high positive surface charge. The powdery solids must therefore, be prepared before incorporating them into the latex in such a way that they cannot cause coagulation for either reason. They are therefore expediently pasted with water and normally provided with protective colloids (generally at least 24 hours of processing in a ball mill). The latter also prevent subsequent agglomeration of the powdery particles and have a high affinity for the powdery particles. Suitable protective colloids are, for example, the water-soluble alkali metal salts of naphthalenesulfonic acid-formaldehyde condensates (for example Tamol NN 4501 from BASF AG; = 45% strength by weight aqueous solution of the sodium salt of a naphthalenesulfonic acid-formaldehyde condensate with a number-average relative molecular weight of 6500) or the water-soluble alkali metal salts of the partial mixed esters (Ci to C _δ alkanols) of styrene / maleic anhydride copolymers (for example K-Scripset ^® 540, produced by mixing 625 g of water, 250 g of 10% by weight aqueous potassium hydroxide solution and 125 g of Scripset 540 from Monsanto (partial methyl / isobutyl mixed ester of a styrene / maleic anhydride copolymer with a molar styrene: maleic anhydride ratio of 1: <1 and a relative weight-average molecular weight of 180,000). The aqueous Anteigung more thickeners are often added (eg Collatex ^® AS / RK, Collatex A / RN or Collatex A / RE of the Kelco; it is these compounds are ammonium alginate, wt their 1 -% aqueous solution.. preferably has a viscosity of 350 to 650 mPa-s (20 ° C., Brookfield viscometer, Model LV, 60 revolutions / min, spindle 3) in order to achieve a paste-like consistency of the paste. Both water-soluble and water-insoluble can be used as vulcanization accelerators Water-insoluble accelerators are preferred because they are not absorbed by porous dipping forms. Among them, the ultra-accelerators of the dithiocarbamate group (eg zinc-N-diethyldithiocarbamate, zinc-N-dimethyldithiocarbamate, zinc-N-dibutyldithiocarbamate) are of particular importance or zinc N-phenyl-ethyl-dithiocarbamate) and the less strongly accelerating compounds of the mercapto-benzothiazole class (eg zinc merca ptobenzothiazole). These solid vulcanization accelerators are also expediently incorporated in an aqueous, pasted form.

Another part of the auxiliaries to be incorporated are viscous liquids (for example Wingstay S = anti-aging agent (antioxidant)), which are generally incorporated as an aqueous emulsion. The emulsifiers and / or surfactants used are preferably those which would also be suitable for carrying out the free-radical aqueous emulsion polymerization and which have a particularly high affinity for the emulsified Show liquid. Other anti-aging agents are Naugawhite and Proxel ^® XL2 (bactericide).

Possible mineral fillers which are insoluble in the aqueous medium are, for example, quartz powder and calcium or aluminum silicates. The vulcanosol dyes and the Halizarin ^® pigments from BASF AG are particularly suitable as dyes. Possible plasticizers are oils such as mineral oil, paraffinol or dibenzyl ether, which were also incorporated as an aqueous emulsion.

According to the invention, suitable electrolytes which are adsorbed on the surface of the molded body are, according to the character of the anionic sulfonate group, u.a. Salts of monovalent or polyvalent cations such as calcium nitrate, calcium chloride, aluminum sulfate, magnesium nitrate or zinc nitrate, which are preferably good

Have water solubility, as well as Bronsted acids, especially strong ones, such as formic acid, acetic acid or lactic acid. Mixtures of such electrolytes are of course also possible. The electrolyte adsorbate is expediently applied to the surface of the shaped body by dipping the shaped body into a solution of the electrolyte and subsequent drying. Lower alcohols, such as methyl and ethyl alcohol, water and / or a mixture thereof, are suitable as solvents. In order to prevent the coagulant solution from contracting and not wetting evenly when the molded article runs out, the pre-immersion solution generally contains a wetting agent in a manner known per se (for example ethoxylated alkylphenols such as Lutensol * 'AP 10 in aqueous pre-immersion solutions) ). Glass, porcelain, ceramic or light metal, which, however, must be free of Cu and Mn, has proven itself as the material for the molded body to be immersed. Often these materials are also covered with a textile fiber fabric, which serves as the basis for the later diving article. Selbstver ^¬ course also heated moldings are suitable. The temperature of the aqueous latex dipping preparation into which the molded body is immersed in the process according to the invention is generally 10 to 40, usually 10 to 30 ° C. It is normally below the cloud point of the nonionic organosilicon surfactant. After dipping into the aqueous latex dipping preparations according to the invention, the polymer film deposited on the surface of the molded body is generally washed in water, dried, vulcanized in hot air and finally stripped, if necessary washed again in water and, if necessary, powdered or chlorinated. Of course, dipping can also be carried out several times in succession in order to achieve particularly high film thicknesses. The process according to the invention ensures films with increased thickness and improved reproducibility as well as a quality corresponding to electrolyte immersion with a shorter immersion time. In addition, the resulting films show an improved grip, as is required in particular with medical gloves. The dipping time required for a certain film thickness can be additionally influenced by varying the polymer content of the aqueous latex dipping preparation. Higher polymer contents generally require shorter dipping times. The aqueous latex dipping preparation is often made alkaline using NH ₃ and left to stand for a long time before dipping (maturing time). During this period, part of the ZnO dissolves, which often proves to be advantageous in the case of carboxylated polymers. Sometimes alkali metal hydroxide such as NaOH is used instead of NH ₃ . The method according to the invention is suitable, for example, for producing diving articles with a film thickness of 0.04 mm to 2 mm. Suitable diving articles are those known per se, ie gloves, condoms, suction cups, balloons, finger cots etc.

Examples

A) Production of latices LI and LII suitable for the production of diving articles

LI: The polymerization was carried out under an N ₂ atmosphere and with the addition of sodium dithionite, which acted here as an oxygen scavenger.

A mixture was placed in a polymerization vessel (stirred pressure reactor made of V2A steel)

out

52 kg water,

23.52 kg butadiene (47.3% by weight), 20.82 kg acrylonitrile (41.9% by weight), 2.90 kg methacrylic acid (5.8% by weight),

3.47 kg 40 wt. -% aqueous solution of the Na salt of secondary alkanesulfonic acid (Cχ ₃ - / Cχ ₇ mixture),

1.03 kg of a 45 wt. -% aqueous solution of the Tamol

NN 4501 corresponding naphthalene-sulfonic acid-formaldehyde condensate (number average relative molecular weight: 6500)), 86 g of sodium sulfate and 40 g of a 40 wt. -% aqueous solution of the sodium salt of ethylenediaminetetraacetic acid

submitted and cooled to 8 ° C.

Then, while maintaining the 8 ° C, 1.5 g of sodium dithionite and then

4 g sodium formaldehyde sulfoxylate, 609 g tert. -Dodecyl mercaptan and

1.5 g Sequestrene Na-Fe (mixed Na-Fe salt of ethylenediaminetetraacetic acid)

all at once. Then 9.0 g of one

90.5% by weight aqueous cumene hydroperoxide solution was added all at once and then polymerized while maintaining the 8 ° C. up to a polymerization conversion of 40 mol%. Then a mixture was suddenly formed

0.45 g Sequestrene Na-Fe,

4 g sodium formaldehyde sulfoxylate and 400 g water

such as

11 g of a 90.5% by weight aqueous cumene hydroperoxide solution

added all at once and the polymerization while maintaining the 8 ° C up to a polymerization conversion of

60 mol% continued. The polymerization temperature was then increased to 10 ° C. and the polymerization was continued at this temperature until a polymerization conversion of 75 mol% had been reached.

Then suddenly

2.51 kg of butadiene (5% by weight) and a mixture of 0.45 g of Sequestrene Na-Fe,

4 g of sodium formaldehyde sulfoxylate and 3.7 kg of water

such as 11 g of a 90.5 wt. -% aqueous cumene hydroperoxide solution

added all at once and the polymerization continued at a temperature of 15 ° C. until a polymerization conversion of 98 mol% had been reached.

By adding a mixture

590 g 25 wt. -% aqueous ammonia solution, 30 g of diethylhydroxylamine and

500 g water

the polymerization was stopped at the aforementioned conversion. The solids content of the aqueous polymer dispersion obtained was 45.5% by weight.

After adding 500 g of a 50 wt. -% aqueous solution of Naugawhite and 100 g of water, the remaining monomers were largely removed by stripping with steam. The resulting aqueous polymer dispersion had a solids content of 44.7% by weight. The weight-average polymer particle diameter d _w was 110 nm and the filming had a ^1H T ₂ value of 4.1 ms.

LII: The polymerization was carried out under an N ₂ atmosphere.

In an inlet vessel I, an inlet I consisting of

11.1 kg acrylonitrile (24% by weight),

22.7 kg butadiene (49.1% by weight), 1.38 kg methacrylic acid (2.9% by weight) and

305 g tert. -Dodecyl mercaptan

maintained.

In an inlet vessel II, an inlet II consisting of

5 kg of water and

2.4 kg of a 40 wt .-% aqueous solution of

Na salt of secondary alkanesulfonic acid (Cι ₃ - / Cι ₇ mixture) held.

A mixture was made in a polymerization vessel (stirred pressure reactor made of V2A steel) 12.9 g of disodium salt of ethylenediaminetetraacetic acid,

5.53 kg butadiene (12% by weight),

5.54 kg of acrylonitrile (12% by weight), 760 g of a 33.5% by weight aqueous poly styrene polymer dispersion (d _w = 30 nm, containing 20% by weight, based on the mass of polystyrene, of the dispersant) Na salt of dodecylbenzosulfonate) as a seed latex

and

37.6 kg of water submitted

and tempered to 53 ° C. Then 930 g of ammonium peroxodisulfate were added to the polymerization vessel and the resulting mixture was polymerized for 0.5 h while maintaining the 53 ° C. Subsequently, while maintaining the 53 ° C., feed I (within 7 hours) and feed II (within 9 hours) were simultaneously fed into the polymerization vessel. After the end of feed II, the polymerization mixture was stirred at 53 ° C. for a further 8 h. Then the polymerization was completed by adding a mixture

180 g 25% by weight aqueous NH ₃ solution,

1600 g water,

46 g of hydroxylamine sulfate and

4.5 g of sodium salt of dodecylbenzenesulfonate stopped.

The solids content of the aqueous polymer dispersion obtained was 49.8% by weight.

After addition of a mixture of 500 g of water and 2.4 kg of a 40 wt. % aqueous solution of the sodium salt of secondary alkanesulfonic acid (C ₃ / C ₁₇ mixture), the remaining monomers were largely removed by stripping with steam.

The resulting aqueous polymer dispersion had a solids content of 48.6% by weight. The weight-average polymer particle diameter d _w was 180 nm and the filming had a ^1H T ₂ value of 2.6 ms.

B) Production of Latex Dipping Preparations LTI to LTIII and Comparative Latex Dipping Preparations VLTI to VLTIII. LTI: In the total amount of the aqueous polymer dispersion LI obtained, a mixture of was used to protect against aging

953 g Wingstay-S, 8.5 g sodium salt of dodecylbenzenesulfonate and

944 g water

and a mixture of

1 kg of water,

1.98 kg of a 25 wt. -% aqueous potassium resinate solution (Dresinat 214 K from Abieta Chemie GmbH in Gersthofen, DE) and 480 g of a 9.5 wt. -% aqueous Proxel XL2 mixture

incorporated.

220 g of the resulting aqueous preparation were removed, adjusted to pH 9 with concentrated aqueous NH ₃ solution and the following constituents were added:

2 g of a mixture

625 g water,

125 g K-Scripset and

250 g 10 wt. -% aqueous potassium hydroxide solution,

10 g of a 10 wt. % aqueous solution of the Tamol NN 4501 corresponding Na salt of a naphthalene sulfonic acid condensate of the relative number average molecular weight of 6500;

7 g of an aqueous preparation of fine-particle ZnO

1000 g ZnO,

10 g Collatex AS / RK,

50 g of a 45 wt. -% aqueous solution of Tamol

NN 4501 corresponding Na salt of a naphthalene sulfonic acid condensate and

910 g water;

1.6 g of an aqueous preparation of finely divided sulfur 910 g water,

60 g of a 45 wt. -% aqueous solution of the Tamol NN 4501 corresponding sodium salt of a naphthalene sulfonic acid condensate, 30 g Collatex AS / RK and

1000 g of sulfur;

1 g of an aqueous preparation of finely divided zinc mercapto-benzothiazole

940 g water,

1000 g zinc mercaptobenzothiazole,

50 g of a 45 wt. % aqueous solution of the Na salt corresponding to Tamol NN 4501, a naphthalene sulfonic acid condensate and

10 g Collatex AS / RK;

1 g of an aqueous preparation of finely divided zinc-N-diethyldithiocarbamate

940 g water

1000 g zinc N-diethyldithiocarbamate

50 g of a 45 wt. -% aqueous solution of the Tamol NN 4501 corresponding Na saltsε a naphthalenesulfonic acid condensate and

10 g Collatex AS / RK;

The preparation was then diluted to a solids content of 40% by weight and left to stand at 25 ° C. for 24 hours (ripening time). Then a mixture was made

1.8 g of water and 0.2 g of Basensol HA 5 were added for the purpose of thermal sensitization and left to ripen again at 25 ° C for 24 h. The resulting coagulation temperature was 44 ° C.

VLTI: Like LTI, but no base sol HA 5 was added.

LTII: The following was incorporated into the total amount of aqueous polymer dispersion LII obtained as protection against aging:

46.2 g of hydroxylamine sulfate,

4.6 g of sodium salt of dodecylbenzenesulfonate,

1.60 kg water,

924 g of a 50 wt. -% aqueous Naugawhite mixture and

370 g of a 9.5 wt. -% aqueous Proxel XL2 mixture. 215 g of the resulting aqueous preparation were removed and prepared in a manner corresponding to how the aqueous polymer dispersion LI containing anti-aging agents added was prepared to LTI.

Instead of 7 g of the aqueous ZnO preparation, however, only 2 g of the aqueous ZnO preparation were added. Furthermore, 2 g of the aqueous sulfur preparation were added in place of the 1.6 g of the aqueous sulfur preparation. Furthermore, the amount of base sol HA 5 added was not 0.2 g but 0.8 g (dissolved in 7.2 g water) and the dilution was carried out to a solids content of 25% by weight. The resulting coagulation temperature was 41 ° C.

VLTII: Like LTII, but no base sol HA 5 was added.

LTIII: Like LTII, but the amount of Basensol HA 5 added was 0.9 g (dissolved in 8.1 g water). Furthermore, only 1 g of aqueous sulfur preparation, but 5 g of aqueous ZnO

Preparation added. After dilution to a solids content of 25% by weight, the coagulation temperature was 42 ° C.

VLTIII: Like LTIII, but no base sol HA 5 was added.

C) Manufacture of diving articles

Three ceramic cylinders (10 cm diameter, 28 cm length, 16 cm immersion depth) VKH1, KH2 and KH3 were used as immersion bodies, which had a temperature of 70 ° C. and differed only from one another in that KH2 and KH3 had a surface on them Ca (N0 ₃ ) ₂ layer adsorbed, which had been applied as follows:

KH2: The pure ceramic cylinder was first heated to 70 ° C and then dipped into a solution at a rate of 100 mm / sec

350 g calcium nitrate,

639 g water,

10 g of glacial and

1 g Lutensol AP10

submerged and then left at 0.1 lake in the same.

The molded body was then removed (at a speed of 20 mm / sec) and dried at 70 ° C. for 180 seconds. KH3: Like KH2, but the calcium nitrate solution was

130 g calcium nitrate,

639 g water, 10 g glacial acetic acid and

1 g Lutensol AP10.

In addition, the immersion bodies VKH1, KH2 and KH3 were immersed in the aqueous latex immersion preparations, which had a temperature of 25 ° C. (with pure thermo-coagulation, the immersion speed was 50 mm / sec and the removal speed was 65 mm / sec; otherwise the immersion speed was 65 mm / sec and the removal speed 10 mm / sec). After a certain dwell time, the immersion bodies were removed again and left to stand at 25 ° C. for 5 minutes. Thereafter, the immersion body having the film deposited during immersion was immersed in 40 ° C. for 5 minutes to wash the films. The mixture was then dried at 70 ° C. for 30 minutes and then vulcanized for a further 30 minutes at 120 ° C. (in air at a corresponding temperature). The film formed was then peeled off and a specimen (type 2 according to ISO 37: 1994 (E)) removed from it was examined at 23 ° C. and 50% relative atmospheric humidity (determination of the film thickness FD in μm; determination of the for an elongation of 100%, 200%, 300% and 500% required tensile force ZK [MPa] standardized to the product of the width and thickness of the test center, the correspondingly standardized tensile strength RK [MPa] and the elongation at break RD (increase in the sample length until tearing, based on the starting length in%) according to ISO 37: 1994 (E)). The following results were obtained:

With the procedure according to the invention, a film thickness increased by more than 50% with an essentially identical property profile was achieved in comparison with pure electrolyte coagulation with the same dwell time.

In the case of pure thermocoagulation, the mechanical properties of the resulting filming were unsatisfactory.

Claims

Process for the production of immersion articles, in which a molded body having a temperature T, the surface of which has an electrolyte adsorbed as a coagulant, is immersed in an aqueous latex immersion preparation which is an aqueous polymer dispersion which, according to the free-radical aqueous emulsion polymerization method, has little at least one monomer containing ethylenically unsaturated groups, which consist at least 30% of its weight from two monomers having conjugated ethylenically unsaturated double bonds, was obtained and, based on the weight of the disperse polymer, was obtained

0.25 to 2.5 wt. * 6 sulfur

0.25 to 10% by weight zinc oxide

0.5 to 1.5% by weight vulcanization accelerator

0.5 to 1.0% by weight of anti-aging agent

0 to 10% by weight insoluble mineral fillers

0 to 1.5% by weight of dyes and

0 to 10% by weight plasticizer

added, with the proviso that

the electrolyte adsorbed on the molded body surface is a Bronsted acid and / or a salt,

the free radical aqueous emulsion polymerization is carried out in the presence of dispersants which consist of at least 50% by weight of water-soluble alkali metal and / or ammonium salts of the monosulfonic acids of cio to C ₂ o-hydrocarbons,

the aqueous latex dipping preparation contains, as a thermal coagulant, a nonionic, organosilicon-containing polyether group with an organosilicon surfactant with a cloud point in the range from 20 to 60 ° C. and

the temperature T is above the cloud point of the organosilicon surfactant.

2. The method according to claim 1, characterized in that the cloud point of the added silicon-organic Tenεidε 30 to 40 ° C is added.

3. The method according to claim 1 or 2, characterized in that the temperature T is> 40 ° C to <150 ° C.

4. The method according to claim 1 to 3, characterized in that the temperature T is 60 to 90 ° C.

5. The method according to claim 1 to 4, characterized in that the free radical aqueous emulsion polymerization is carried out in the presence of dispersants which contain at least 75% by weight of water-insoluble alkali metal and / or ammonium salts of the monosulfonic acids of Cχo to C ₂ o-Kohlenwaεεerεtoffen exist.

6. The method according to claim 1 to 4, characterized in that the free radical aqueous emulsion polymerization is carried out in the presence of dispersants which consist exclusively of water-soluble alkali metal and / or ammonium salts of the mono-sulfonic acids of Cio to C ₂ rj-kohlwaεserstoffen.

7. The method according to claim 1 biε 6, characterized in that as at least one alkali metal and / or ammonium salt

Monosulfonic acid from Cio to C ₂ rj-kohlwaεεerεtoffen a Cio to Cχ ₃ alkylbenzenesulfonate is also used.

8. The method according to claim 1 to 6, characterized in that as at least one alkali metal and / or ammonium salt

Monosulfonic acid from Cio-biε C ₂₀ hydrocarbons, a C ₁₃ - bi-C _B alkane sulfonate is also used.

9. The method according to claim 1 to 8, characterized in that the nonionic, polyether groups having ε, εilicon- organiεcheε Tenεid Basensol HA 5 is used.

10. The method according to claim 1 to 8, characterized in that the non-ionic, polyether group-containing, silicon-organic surfactant Coagulant WS is used.

11. The method according to claim 1 to 10, characterized in that the weight-average diameter of the dispersed polymer particles is 80 to 300 nm.

12. The method according to claim 1 to 10, characterized in that the weight-average diameter of the dispersed polymer particles is 100 to 250 nm.

5 13. The method according to claim 1 to 10, characterized in that the weight-average diameter of the dispersed polymer particles is 100 to 200 nm.

14. The method according to claim 1 to 13, characterized in that 10 that the aqueous polymer dispersion by the method of free radical aqueous emulsion polymerization of a monomer mixture

30 to 100% by weight of at least one, two conjugated 15 ethylenically unsaturated groups, monomers (monomers A),

0 to 10% by weight of one or more monoethylenically unsaturated monomers whose molar water solubility at 25 ° C. and 1 atm> is the corresponding molar water solubility of acrylonitrile (monomers B)

0 to 70% by weight of one or more monoethylenically unsaturated monomers whose molar water solubility at 25 ° C. and 1 atm <is the corresponding molar water solubility of acrylonitrile (monomers C),

30 was obtained.

15. The method according to claim 14, characterized in that the monomers A comprise at least one monomer from the group comprising butadiene, 2-methyl-butadiene, 2, 3-dimethylbutadiene, penta-

35 are 1.3 and pentadiene 2.4.

16. The method according to claim 14 or 15, characterized in that as monomers B one or more monomers from the group comprising 3 to 6 carbon atoms having α, β-monoethylenic

40 unsaturated mono- and dicarboxylic acids, the salts of these

Carboxylic acids, the amides of these carboxylic acids, vinylsulfonic acid, the salts of vinylsulfonic acid and N-vinylpyrrolidone are used.

45 17. The method according to claim 14 to 16, characterized in that one or more monomers from the group comprising styrene, vinyl toluene, o-chlorostyrene, acrylonitrile, as monomers C, Methacrylonitrile and esters of acrylic or methacrylic acid with alkanols containing 1 to 8 carbon atoms can be used.

18. The method according to claim 14 to 17, characterized in that

5 that only butadiene is used as monomer A.

19. The method according to claim 14 to 18, characterized in that only methacrylic acid is used as monomer B.

10

20. The method according to claim 14 to 19, characterized in that acrylonitrile or styrene is used as the monomer C.

21. The method according to claim 14 to 20, characterized in that the composition of the monomer mixture to be polymerized according to the method of radical aqueous emulsion polymerization

30 to 90% by weight of monomers A, 20 1 to 10% by weight of monomers B and

9 to 60% by weight of monomers C

consists.

25 22. The method of claim 14 to 21, characterized in that the composition of the intermetallic by the method of Radika ^¬ aqueous Emulsionεpolymerisation to be polymerized monomer mixtures of

30 45 to 70% by weight of monomers A,

3 to 10% by weight of monomers B and 27 to 45% by weight of monomers C

consists.

35

23. The method according to claim 22, characterized in that da monomers A = butadiene, da monomers B = methacrylic acid and da monomers C = acrylonitrile.

40 24. The method according to claim 14 to 23, characterized in that the filming of the aqueous polymer dispersion obtained in the free radical aqueous emulsion polymerization has a transverse nuclear magnetic relaxation time of the protons ^1H T ₂ chemically bound to the polymer from 2.5 to

45 has 4.5 ms.