RU2171813C2 - Water-soluble cross-linkable protective colloids, method of preparing aqueous dispersions of polymers stabilized by protective colloids, aqueous polymer dispersions, and polymer powder compositions suitable for redispersing in water - Google Patents

Abstract

FIELD: polymer materials. SUBSTANCE: water-soluble cross-linkable protective colloids have molecular weight at least 500000 and contain: (i) at least 20% of monomer units containing sulfate or sulfonate groups; (ii) 4-80 % of monomer units containing N-methylol or N- alkoxymethylol groups; (iii) 0.1-20% of hydrophobic monomer units selected from water-insoluble ethylenically unsaturated compounds and hydrophobic terminal groups of initiators or regulatory molecules, all percentages being based on the total copolymer weight. A part of sulfate/sulfonate monomer units in amounts up to 50%, if necessary, can be substituted by carboxy- or amide-containing monomer units. Polymer dispersions are prepared by radical polymerization of ethylenically unsaturated monomers utilizing suspension or emulsion polymerization technique in presence of at least one cross-linkable protective colloid. Aqueous polymer dispersions as well as polymer powder compositions suitable for redispersing in water are useful as binding agents for coatings, plasterwork, and varnish-and-paint materials, as sizing and binding substances in papermaking and textile production, as concrete additives, etc. EFFECT: improved consumer's quality and optimized preparation procedure. 11 cl, 1 tbl, 8 ex

Description

 The invention relates to crosslinkable protective colloids, a method for the polymerization of ethylenically unsaturated monomers using crosslinkable protective colloids, as well as to polymers obtained therefrom, respectively, polymer dispersions and their use.

 The stabilization of polymer dispersions with protective colloids and surfactants is known. A review of stabilizers used can be found, for example, in G. Schulz "Die Kunststoffe", published by C. Hanser Verlag, 1964, or J.C. Jonson "Emulsifiers and Emulsifying Techniques" Noyes Data Corp., Park Ridge, New Jersey, 1979, and also in the Ullmann Encyclopedia (Ullmann, "Encyklopadie der technischen Chemie", 4th ed., Vol. 10, publ. Verlag Weinheim, 1980).

 These compounds are distinguished by the presence of a hydrophilic and hydrophobic moiety in the molecule, the latter being used to adhere to the polymer resin. According to a widespread assumption, these surfactants are predominantly located in the boundary layer between the polymer particles and the aqueous solution. Therefore, the overall surface of the system, and thus, ultimately, the properties of the polymer dispersion is largely determined by these stabilizers. Thus, the choice of an appropriate emulsifier ultimately determines the necessary target properties of the polymer dispersion.

 The use of surfactant polymers as protective colloids is also often described in the patent literature of recent years. Moreover, unlike classical polymer protective colloids, such as polyvinyl alcohol, cellulose or gelatin derivatives, new synthesis methods have been developed, and water-soluble polymers with ionic groups, the so-called polyelectrolytes, are used as protective colloids.

 From DE 4212768 (US 5385971), an unsaturated polyester from the group of polyethylene glycol esters of maleic or fumaric acid is known, which is used to stabilize polymer emulsions. The polymer dispersions thus obtained are characterized by high frost resistance and resistance to electrolytes. DE-A 4304014 (WO-A 94/18249) describes a process for the continuous polymerization of acrylic polymers with a low degree of polymerization in an aqueous medium. The polymers obtained in this way are suitable as auxiliary dispersing agents for pigments and binders. However, the disadvantage of these products is a certain thickening effect, which is undesirable for many applications.

 The stabilization of dispersions using electrolytes is also known from DE 2540468 (GB-A 1551126), where there is a high resistance of the obtained dispersions to the action of salts and shear stresses. WO 92/03482 describes oligomeric carboxylic acids used as stabilizers for emulsion polymerization of radically polymerizable monomers, which are particularly suitable for the preparation of binders for printing inks. No. 5,314,943 discloses dispersions of binders for use in the textile industry. The polymer dispersions described in this publication are stabilized with a protective colloid containing carboxylic acid groups. This system is believed to be capable of rapid cure.

 To obtain binders that provide the formation of extremely stable polymer films, for example, when used as adhesives or coatings, aqueous polymer dispersions of crosslinkable polymers are often used. Crosslinkable polymers with N-methylol-functional comonomer units as crosslinking groups are widely used. Such crosslinkable polymers are known, for example, from DE-C 2512589 (US 4044197). However, the strength of polymer films thus obtained cannot be improved simply by increasing the proportion of N-methylol-functional units in the polymer. Therefore, in the prior art, it was proposed to increase the crosslinking efficiency of such polymers using special preparation methods (EP-B 205862) or to polymerize comonomers with blocked N-methylol functions (EP-A 261378).

 Thus, based on this prior art, the basis of the invention was the task of obtaining polymers or aqueous dispersions of polymers that could form polymer films having high mechanical strength and high water resistance and resistance to solvents.

 This problem was solved by obtaining a water-soluble crosslinkable polymer having protective colloid properties, having functional groups built into the molecular chain capable of self-crosslinking, in particular N-methylol groups.

 Water-soluble polymers with a high content of NMA (N-methylolacrylamide) tend to have a high molecular weight and, consequently, a high viscosity aqueous solution. Water-soluble acrylic compounds, such as acrylic acid or N-methylolacrylamide, used as a crosslinking agent, are prone to a very high degree of polymerization, which significantly limits their applicability due to the resulting high viscosity. For example, EP-B 94898 (US-A 4,736,005) describes the preparation of especially high molecular weight (MB> 1,000,000) terpolymers from 30-95% dimethylacrylamide (DMA), 0.1-10% N-methylolacrylamide (NMA) and 4-50% acrylamidomethyl propanesulfonate ( AMPS) and their use as rheological additives in oil production.

 Another disadvantage of polyelectrolytes based on water-soluble monomers is that such polyelectrolytes are often incompatible with polymer dispersion and the aqueous solution of the polyelectrolyte is separated from the polymer dispersion in the form of serum.

 It was unexpectedly found that by copolymerization of N-methylolacrylamide with acrylic compounds containing sulfonic acid or sulfonate groups, it is possible to obtain a product with a significantly lower molecular weight. In addition, it was unexpectedly found that already in the copolymerization of only small amounts of hydrophobic copolymers there is a noticeably lower surface tension and lower viscosity.

The problem is achieved by water-soluble crosslinkable protective colloids for aqueous dispersions of polymers having a molecular weight of less than 500,000, containing
a) at least 20 wt.% monomer units containing sulfonic acid or sulfonate groups,
b) 4-80 wt.% monomer units containing N-methylol or N-alkoxymethyl groups,
c) 0.1-20 wt.% hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds and hydrophobic end groups of residues of initiators or regulatory molecules, the amounts expressed in wt.% are relative to the total weight of the copolymer, and
moreover, part of the monomer units containing sulfonic acid / sulfonate groups, if necessary up to 50 wt.% in terms of the weight amount of monomer units a), can be replaced by monomer units d) containing carboxyl groups, or monomeric units e) containing amide groups.

Preferred are water soluble crosslinkable protective colloids containing:
a) 70-87 wt.% monomer units containing sulfonic acid or sulfonate groups,
b) 12-25 wt.% monomer units containing N-methylol or N-alkoxymethyl groups,
c) 1-5 weight. % hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds.

 As monomer units a) the colloids preferably contain 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, sulfopropyl ether of acrylic acid, sulfopropyl ether of itaconic acid, vinyl sulfonic acid or their salts of ammonium, sodium, potassium and calcium; b) contain N-methylolacrylamide, N-methylol methacrylamide, N- (isobutoxymethyl) acrylamide, N- (isobutoxymethyl) methacrylamide or N- (n-butoxymethyl) acrylamide as monomer units; and as monomer units c) contain methyl methacrylate, styrene, vinyl propionate, isopropenyl acetate, vinyl laurate or vinyl ester of α-branched monocarboxylic acids with 5-10 carbon atoms.

 The problem is also solved by the method of producing aqueous dispersions of polymers stabilized by protective colloids by radical polymerization of ethylenically unsaturated monomers by the method of suspension or emulsion polymerization, in which the polymerization is carried out in the presence of at least one of the crosslinkable protective colloid described above.

 It is preferable to carry out the polymerization by the method of emulsion polymerization in the presence of one or more monomers from the group of vinyl esters of unbranched or branched carboxylic acids with 1-18 carbon atoms, esters of acrylic acid and methacrylic acid with unbranched or branched alcohols with 1-18 carbon atoms, vinyl aromatic compounds vinyl halides and olefins.

 The task is also achieved by aqueous polymer dispersions of ethylene unsaturated monomer polymers that contain 0.1-20 wt.% Of one or more of the protective colloids described above, calculated on the amount of solid material in the polymer.

Aqueous polymer dispersions may contain one or more polymers based on vinyl esters or polymers based on (meth) acrylic acid esters, which, in terms of the total weight of the polymers, do not necessarily contain another 0.5-5.0 wt.% Comonomer units with a crosslinking effect of a group comprising N-methyl acrylamide, N-methylol methacrylamide, N- (alkoxymethyl) acrylamides or N- (alkoxymethyl) methacrylamides with a C ₁ -C ₆ alkyl radical.

 Aqueous polymer dispersions preferably contain a copolymer of vinyl acetate and ethylene with an ethylene content of from 5 to 50 wt.% And a content of from 0.5 to 5.0 wt.% Of one or more comonomers from the group comprising N-methylolacrylamide, N-methylol methacrylamide, N- (isobutoxymethyl) acrylamide, N- (isobutoxymethyl) methacrylamide, N- (n-butoxymethyl) acrylamide, N- (n-butoxymethyl) methacrylamide.

 The task is also achieved by the above-described aqueous dispersions of polymers used as binders for coatings, plasters and paints, in particular pigmented paints; as adhesives and binders for wood, paper, textiles and non-woven materials; as binders in the manufacture of paper and the manufacture of press materials and molded products; as binders for use in the construction industry, in particular as additives to concrete, building adhesives, mortar, putty and filling masses.

 The task is also achieved by water-redispersible polymer powder compositions obtained by spray drying the above-described aqueous dispersion of polymers, which can be used in the same areas as aqueous dispersions of polymers.

In addition, water soluble crosslinkable protective colloids with a molecular weight of ≅ 500,000 containing
a) 30-87 wt.% monomer units containing sulfonic acid or sulfonate groups,
b) 12-60 wt.% monomer units containing N-methylol or N-alkoxymethyl groups,
c) 0.1-10 wt.% hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds and hydrophobic end groups of residues of initiators or regulatory molecules, and the amounts in wt.% are indicated in relation to the total weight of the copolymer.

Particularly preferred are water soluble crosslinkable protective colloids with a molecular weight of ≅ 500,000 containing
a) 70-87 wt.% monomer units containing sulfonic acid or sulfonate groups,
b) 12-25 wt.% monomer units containing N-methylol or N-alkoxymethyl groups,
c) 1-5 weight. % hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds and hydrophobic end groups of residues of initiators or regulatory molecules, and the amounts in wt.% are indicated in relation to the total weight of the copolymer.

Suitable monomer units a) are, for example, water-soluble, radically polymerizable ethylenically unsaturated compounds that contain sulfonic acid or sulfonate groups —SO ₃ M, where M is H, an alkali metal ion, an ammonium ion or an alkaline earth metal ion. Preferred are 2-acrylamido-2-methylpropanesulfonic acid (AMPK), styrene sulfonic acid, sulfoalkyl ether (meta) acrylic acid, sulfonic alkyl ether of itaconic acid, preferably in each case a C ₁ -C ₆ alkyl radical, vinyl sulfonic acid and their ammonium salts, alkali or alkali salts earth metals. Particularly preferred are 2-acrylamido-2-methylpropanesulfonic acid (AMPK), styrene sulfonic acid, sulfopropyl ether of acrylic acid, sulfopropyl ether of itaconic acid, vinyl sulfonic acid and their salts of ammonium, sodium, potassium and calcium.

Suitable monomer units b) are, for example, water-soluble, radically polymerizable ethylenically unsaturated compounds that contain N-methylol groups (-NH-CH ₂ OH) or their esterified derivatives (-NH-CH ₂ OR, where R is C ₁ -C ₆ alkyl) . Preferred are N-methylolacrylamide (NMA), N-methylol methacrylamide (NMMA), N- (isobutoxymethyl) acrylamide (IBMA), N- (isobutoxymethyl) methacrylamide, N- (n-butoxymethyl) acrylamide (NBMA). Of these, N-methylolacrylamide, N- (isobutoxymethyl) acrylamide are particularly preferred.

Suitable monomer units c) are radically (co) polymerizable ethylenically unsaturated compounds whose solubility in water at a temperature of 23 ^o C is less than 2 wt.%, As well as hydrophobic end groups of residues of initiators or regulatory molecules, in each case with more than 8 carbon atoms . More preferred are esters of acrylic acid or methacrylic acid with more than 3 carbon atoms such as methyl methacrylate, vinyl aromatic hydrocarbons such as styrene or vinyl toluene, olefins such as ethylene or propylene, vinyl halides such as vinyl chloride, vinyl esters of aliphatic carboxylic acids with more than 2 carbon atoms. As the terminal group of regulatory molecules, a dodecyl residue of dodecyl mercaptan is preferred. Methyl methacrylate, styrene, vinyl propionate, isopropenyl acetate (1-methyl vinyl acetate), vinyl laurate, vinyl esters of α-branched monocarboxylic acids with 5-10 carbon atoms such as VeoVa9 ^R or VeoVa10 ^{R are} particularly preferred.

Suitable monomers d) containing carboxyl groups are water-soluble, radically polymerizable ethylenically unsaturated compounds that contain -COOM carboxyl groups, where M is H, alkali metal, ammonium or alkaline earth metal ions. Acrylic acid, methacrylic acid, crotonic acid, itaconic acid are preferred. Suitable monomers e) containing amide groups are water-soluble, radically polymerizable ethylenically unsaturated compounds which contain the amide groups —CONH ₂ . Acrylamide and methacrylamide are preferred; acrylamide is particularly preferred.

The definition of "water soluble", in principle, means that the solubility in water at a temperature of 23 ^o C is at least 10 wt.%. Molecular weight is the average weight determined by gel permeation chromatography (GPC) using sodium polystyrenesulfonate as a standard.

The preparation of protective colloids according to the invention is preferably carried out by radical polymerization in an aqueous solution at a reaction temperature preferably in the range of 40 to 80 ^° C. The polymerization can be carried out by pre-loading all or individual components of the reaction mixture into the apparatus or by pre-loading part of the reagents and then dosing all or individual components of the reaction mixture, or dosing can be carried out without pre-loading.

 The initiation is carried out using radical generators commonly used for these purposes, which are preferably used 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 persulfate, hydrogen peroxide, potassium, sodium and ammonium peroxodiphosphate. If necessary, these radical polymerization initiators can also be conventionally combined with 0.01-1.0 wt.%, Based on the total weight of the monomers, the redox agent, in which case the polymerization can be carried out at lower temperatures. Suitable for these purposes are, for example, alkali metal formaldehyde sulfoxylates and ascorbic acid. Moreover, in cases of redox initiation, it is preferable to dose one or both of the redox components of the catalyst during polymerization.

 The pH range required for polymerization, which is typically ≥ 2.5, can be adjusted in the usual way using bases or conventional buffer salts such as alkali metal phosphates or carbonates. In order to provide the desired molecular weight of the polymers during the polymerization, commonly used regulators are used, for example, such as mercaptans, aldehydes and chlorinated hydrocarbons.

In one particularly preferred embodiment, a part of the comonomer mixture a), b), c) and, if necessary, d) and e) are first placed in the apparatus in the form of an aqueous solution and this mixture is heated to the reaction temperature. Upon reaching the polymerization temperature, a slow dosing of the radical generator and the rest of the mixture of comonomers, respectively, in an aqueous solution is carried out, after which the polymerization is continued until it is completed by heating the mixture to 85-95 ^o C.

 In accordance with the most preferred embodiment, at least one part of the comonomers containing sulfonate groups a) is usually first charged to the apparatus, typically 5-60% by weight, based on the total weight of the comonomers a), as well as part of the comonomers b) with N-methylol -functions, usually comprising 5-60 wt.% in terms of the total weight of the comonomers a), in the form of an aqueous solution, after which the rest of the comonomers a) and b) are added.

 The copolymers are preferably used in the form of their aqueous solutions. Depending on the application, the preferred solids content is controlled in the range of 15 to 25% by weight.

Methods for preparing aqueous dispersions of polymers stabilized by protective colloids by radical polymerization of ethylenically unsaturated monomers by the method of suspension or emulsion polymerization include polymerization in the presence of one or more protective colloids with a molecular weight of ≅ 500,000, containing
a) at least 20 wt.% monomer units containing sulfonic acid or sulfonate groups,
b) 4-80 weight. % monomer units containing N-methylol or N-alkoxymethyl groups,
c) 0.1-20 wt.% hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds and hydrophobic end groups of residues of initiators or regulatory molecules,
moreover, the amount, expressed in wt.%, are calculated in terms of the total weight of the copolymer and
moreover, part of the monomer units containing sulfonic acid / sulfonate groups, if necessary up to 50 wt.%, calculated on the weight basis of the monomer units a), can be replaced by the monomer units containing carboxyl groups d) or the monomeric units containing amide groups e).

 The polymerization is carried out in the presence of one or more monomers from the group of vinyl esters of unbranched or branched carboxylic acids with 1-18 carbon atoms, esters of acrylic acid and methacrylic acid with unbranched or branched alcohols with 1-18 carbon atoms, vinyl aromatic hydrocarbons, vinyl halides and olefins.

Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methyl vinyl acetate, vinyl pivalate and vinyl esters of α-branched monocarboxylic acids with 5 or 9-10 carbon atoms, for example, VV5 ^R , VeoVa10 ^R or VeoVa9 ^R 10 or VeoVa 9 ^R 9 . Vinyl acetate is particularly preferred.

 Preferred methacrylic acid esters or acrylic acid esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, 2-ethyl acrylate, tert-butyl acrylate, 2-ethyl acrylate, Methacrylate, methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred.

 Preferred vinyl aromatic hydrocarbons are styrene, α-methyl styrene, o-chloride styrene or vinyl toluene.

 Preferred vinyl halides are vinyl chloride and vinylidene chloride.

 Preferred olefins are ethylene, propylene, 1,3-butadiene, isoprene.

 To improve solubility in water, to crosslink, or to modify the adhesive properties of polymers, an additional 0.05-30.0 wt.%, Preferably 0.5-15 wt.%, Respectively, based on the total weight of the monomers, can be added to the systems, if necessary. one or more auxiliary monomers.

 Suitable auxiliary monomers for improving water solubility are, for example, α, β-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide, methacrylamide; ethylenically unsaturated sulfonic acids or their salts, preferably vinyl sulfonic acid, 2-acrylamidopropanesulfonate and / or N-vinylpyrrolidone.

Monomers with a crosslinking effect are preferably used in concentrations up to 0.5-5.0 wt.% In terms of the total weight of the monomers. Examples of these are N-methylolacrylamide, N-methylol methacrylamide, N- (alkoxymethyl) acrylamides or N- (alkoxymethyl) methacrylamides with a C ₁ -C ₆ alkyl group, such as N- (isobutoxymethyl) acrylamide (IBMA), N- (isobutoximet) methacrylamide (IBMMA), N- (n-butoxymethyl) acrylamide (NBMA), N- (n-butoxymethyl) methacrylamide (NBMMA); multiply ethylenically unsaturated comonomers, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, propilenglikoldiakrilat, divinyl adipate, divinyl benzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl phthalate, diallilfumarat, methylenebisacrylamide, tsiklopentadienilakrilat or triallyl cyanurate.

 Suitable comonomer units for modifying the adhesion properties are, for example, hydroxyalkyl esters of methacrylic acid and acrylic acid, such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, as well as compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate.

 Obtaining aqueous dispersions of polymers is carried out by the method of aqueous emulsion polymerization or by the method of aqueous suspension polymerization in the presence of 0.1-20 weight. %, preferably 0.1-5.0 wt.%, respectively, calculated on the total weight of the monomers, one or more crosslinkable protective colloids according to the invention. It is preferable to work by the method of emulsion polymerization, which is explained below in more detail.

The polymerization temperature, as a rule, is 35-95 ^o C, preferably 40-80 ^o C. The polymerization can be carried out according to the periodic scheme, in which all components are loaded into the reactor immediately, and by the method of metered supply, in which individual or several components are fed into apparatus during polymerization. Mixed type is preferred: pre-loading and subsequent metered feeding.

 The latter can be carried out separately (spatially and in time) or the components introduced into the process can be all or partially subjected to preliminary emulsification.

 Stitched protective colloids can be loaded immediately, either fed during the reaction or distributed between initial loading and subsequent metered feeding. The crosslinkable protective colloids in the form of their aqueous solutions are preferably introduced during the reaction. Such a feed can be carried out at a constant speed or at variable speeds. The same principles apply for using a system with initiators as for using other reaction components.

 If, for example, gaseous reaction components are used, emulsion polymerization can also be carried out at elevated pressure. If, for example, they are operated at elevated pressure using monomers such as vinyl chloride or ethylene, then preferably a pressure of from 5 to 100 bar. Determining is, for example, the target amount of ethylene to be polymerized.

 The crosslinkable protective colloids used according to the invention can be used both individually and in combination with emulsifiers and / or other protective colloids. According to a preferred embodiment, in addition to the crosslinkable protective colloids according to the invention, one or more emulsifiers are additionally used.

As such additional "concomitant" emulsifiers can be considered emulsifiers of anionic, cationic, as well as non-ionic type. If the polymerization is carried out in the presence of emulsifiers, then their amount is predominantly up to 4 wt.% In terms of the total weight of the monomer phase. Anionic and nonionic emulsifiers are preferred. The emulsifiers used for these purposes are, for example, ethoxylated fatty alcohols with C ₈ -C ₃₆ alkyl groups and an ethoxylation degree (EO degree) of from 3 to 50; ethoxylated mono-, di- and trialkylphenols with C ₄ -C ₁₀ alkyl groups and a degree of EO from 3 to 50; alkali metal salts of di-C ₄ -C ₁₂ alkyl esters of sulfosuccinic acid. Alkali metal and ammonium salts of C ₈ -C ₁₂ alkyl sulfates, ethoxylated alkanols with a C ₁₂ -C ₁₈ alkyl group and with a degree of EO from 3 to 30, ethoxylated C ₄ -C ₁₀ alkyl phenols with a degree of EO from 3 to 50, C _{12 are} also acceptable. -C ₁₈ alkyl sulphonic acids, C ₉ -C ₁₈ alkylaryl sulphonic acids and ethoxylated linear and branched C ₈ -C ₃₆ sulphonates of alkyl alcohols with a degree of EO from 3 to 50.

 Suitable protective colloids which, if necessary, can be used in addition to the crosslinkable protective colloids according to the invention are polyvinyl alcohols, partially saponified polyvinyl acetates, cellulose ethers such as methyl, methyl hydroxypropyl, hydroxyethyl cellulose, carboxymethyl cellulose.

The polymerization is initiated using water-soluble thermal initiators or a combination of redox initiators used in emulsion polymerization. Examples of thermal initiators are organic peroxides, such as tert-butyl hydroperoxide, cumyl hydroperoxide, or peroxodisulfates, such as potassium peroxodisulfate, ammonium peroxodisulfate, or hydrogen peroxide or azo compounds, such as azodiisobutyronitrile. Hydrogen peroxide, tert-butyl hydroperoxide, potassium peroxodisulfate or ammonium peroxodisulfate in combination with hydroxymethanesulfonic acid, ascorbic acid or sodium sulfite are preferably used as redox initiators. It is advisable to increase the reactivity of the initiator system by adding metal ions with variable valency. Fe ²⁺ or Ce ²⁺ ions are preferably used. The amount of initiator is preferably from 0.01 to 1.0 wt.% In terms of the total weight of the monomer phase.

 To regulate the molecular weight during the polymerization, regulatory agents can be used. Usually they are used in amounts of from 0.01 to 5.0 weight. % with respect to the polymerizable monomers and fed into the system separately or pre-mixed with reagents. Examples of such substances are dodecyl mercaptan, mercaptopropionic acid, mercaptopropionic acid methyl ester, isopropanol and acetaldehyde.

 Obtained by the method according to the invention, aqueous dispersions contain solids in an amount of from 30 to 75 wt.%, Preferably from 40 to 65 wt.%.

 Aqueous polymer dispersions of polymers from ethylenically unsaturated monomers contain 0.1 to 20% by weight, based on the solid content of the polymer, of the crosslinkable protective colloids of the invention.

 These polymer dispersions can be prepared according to the present technology according to the invention. In addition, aqueous dispersions of the polymers according to the invention can also be prepared by adding 0.1-20 wt.%, Preferably 0.1-5 wt.%, Respectively, based on the solid content of the polymer, crosslinkable to the polymer dispersions obtained by conventional methods. colloid according to the invention. With additional additives, the protective colloid according to the invention can be introduced into the system in solid form; however, it is preferable to add it in the form of an aqueous solution.

Polymer dispersions of the following polymers are preferred:
Preferred vinyl ester polymers contain as monomer units, in each case, with respect to the total polymer weight:
50-100 wt.% Vinyl ether, in particular vinyl acetate;
50-95 weight. % vinyl ether, in particular vinyl acetate, as well as 5-50 wt.% α-olefin, in particular ethylene;
20-79 weight. % vinyl ether, in particular vinyl acetate, as well as 1-30 wt.% ethylene and 20-49 wt.% vinyl chloride;
50-75 wt.% Vinyl acetate, 1-30 wt.% Vinyl laurate or vinyl ester of α-branched carboxylic acid, in particular Versatic acid vinyl ester, as well as 5-40 wt.% Ethylene;
70-99 wt.% Vinyl acetate and 1-30 wt.% Vinyl laurate or vinyl ester of α-branched carboxylic acid, in particular Versatic acid vinyl ester;
70-99 weight. % vinyl ester, in particular vinyl acetate, and 1-30 wt.% acrylic acid ester, in particular n-butyl acrylate or 2-ethylhexyl acrylate;
50-75 wt.% Vinyl acetate, 1-30 wt.% Ester of acrylic acid, in particular n-butyl acrylate or 2-ethylhexyl acrylate, as well as 5-40 wt.% Ethylene;
30-75 wt.% Vinyl acetate, 1-30 wt.% Vinyl laurate or vinyl ester of α-branched carboxylic acid, in particular Versatic acid vinyl ester, 1-30 wt.% Acrylic acid ester, in particular n-butyl acrylate or 2 ethylhexyl acrylate, as well as 5-40 wt.% ethylene.

Preferred polymers obtained using esters of (meth) acrylic acid as monomer units contain, in each case, calculated on the total weight of the polymer:
35-65 weight. % methyl methacrylate, 65-35 wt.% n-butyl acrylate and / or 2-ethylhexyl acrylate;
35-65 weight. % styrene and 65-35 wt.% n-butyl acrylate and / or 2-ethylhexyl acrylate.

Particularly preferred are polymers of this composition obtained with vinyl esters and (meth) acrylic esters, which contain another 0.5-5.0 wt.%, Based on the total weight of polymers, comonomer units having a crosslinking effect, from the group including N-methylolacrylamide, N-methylol methacrylamide; N- (alkoxymethyl) acrylamides or N- (alkoxymethyl) methacrylamides with C ₁ -C ₆ alkyl groups, such as N- (isobutoxymethyl) acrylamide (IBMA), N- (isobutoxymethyl) methacrylamide (IBMMA), N- (n-butoxymethyl) ) acrylamide (NBMA), N- (n-butoxymethyl) methacrylamide (NBMA).

 Most preferred are copolymers of vinyl acetate and ethylene with an ethylene content of from 5 to 50 wt.% And a content of from 0.5 to 5.0 wt.% Of one or more comonomers from the group consisting of N-methylolacrylamide, N-methylol methacrylamide, N- (isobutoxymethyl ) acrylamide (IBMA), N- (isobutoxymethyl) methacrylamide (IBMMA), N- (n-butoxymethyl) acrylamide (NBMA), N- (n-butoxymethyl) methacrylamide (NBMMA).

 The aforementioned aqueous polymer dispersions of polymers derived from ethylenically unsaturated monomers, which contain 0.1-20 wt.%, In terms of the content in the polymer of a solid material, a crosslinkable protective colloid according to the invention are also suitable for producing water-redispersible polymer powders.

 To obtain redispersible compositions of polymer powders, aqueous dispersions are dried. It is preferable to dry the dispersion by spray drying or freeze drying.

Most preferred is spray drying of the dispersions. You can use known devices, for example, those where spraying is carried out through single, double or multi-jet nozzles or using rotating disks, and carry out drying, if necessary, in a heated current of a drying agent, preferably air. Typically, the temperature of the drying agent at the inlet does not exceed 250 ^o C. The temperature of the drying agent at the outlet is usually in the range from 45 to 100 ^o C, preferably from 55 to 90 ^o C, which depends on the installation, the composition of the polymer and the required degree of drying.

 For drying, the content of solid material in the dispersion is set in the range from 10 to 75 weight. %, preferably from 30 to 65 wt.%. The solids content depends on the selected drying method and on the type and amount of other additives that are introduced during drying. For a preferred spray drying, the viscosity of the entire system was found to be of the order of 1000 MPa · s.

 For example, before drying, dispersion aids can be added to the dispersion. Such additives are preferably introduced in the form of their aqueous solutions, in amounts of preferably 5-40 wt.%, Especially 5-20 wt.% In relation to the polymer. The optimal amount is determined by the required stability of the dispersion, the glass transition temperature of the obtained polymer and the necessary properties of the powder.

As auxiliary spraying agents, among others, split or modified starch, starch derivatives, cellulose derivatives and water-soluble polymers, in particular those having a high glass transition temperature of at least 50 ^° C, are suitable, individually or in an appropriate combination ^. Examples of such commercially available polymers are: vinyl alcohol copolymers (polyvinyl alcohol) with a hydrolysis degree of from 85 to 94 mol% and a Heppler viscosity of from 3 to 25 mPa · s, about limited in a 4% solution; water-soluble sulfonate-containing condensates of melamine and formaldehyde or naphthalene and formaldehyde; condensates of phenolsulfonic acid and formaldehyde; copolymers of styrene and maleic acid and / or itaconic acid and their esters; water-soluble copolymers of olefinically unsaturated acids and alkenes.

 It has been repeatedly established that it was advisable to use antifoam when spraying in an optimal amount of about 1.5 wt.% With respect to the base polymer. Liquid antifoams are usually added to the dispersion before drying, and solid can be mixed with dry dispersion powder compositions.

 In order to increase storage stability by increasing the resistance to adhesion, in particular for powders with a low glass transition temperature, preferably in an amount up to 30 wt.% With respect to the total weight of the polymer components, an anti-sticking agent (caking) can be added to the obtained powder. This is preferably carried out while the powder still remains in finely divided form, for example, while it is still suspended in the drying gas. The adhesion preventing agent can, in particular, be fed to the dryer separately, but at the same time as dispersion. Examples of these anti-caking agents are finely ground aluminosilicates, kieselguhr, colloidal silica gel, pyrogenic silicic acid, precipitated silicic acid, microdinas, light spar, kaolin, talc, cements, diatomaceous earth, calcium carbonate or magnesium hydrosilicate.

 The polymer dispersions containing crosslinkable protective colloids according to the invention or dispersion powders obtained from them are suitable for use as binders for applied coatings, plasters and paints, especially for pigmented paints and varnishes; as adhesives or binders for wood, paper, textiles and non-woven materials; as binders in the manufacture of paper and press materials and molded products; as binders for use in the construction industry, primarily as additives to concrete, building adhesives, putty, mortar and bottling aids.

 The following are examples illustrating the present invention.

Examples
Example 1
Preparation of approximately 16% polymer solution AMPK-NMA-MMA:
Preparation of the dosing solution of monomers: 459 g of water is placed in an appropriate dosing vessel and the following substances are successively dissolved: 81.5 g of a 25% NaOH solution, 0.849 g of MPC mercaptopropionic acid, 4.18 g of methyl methacrylate, 180 g of 2-acrylamino-2- AMPK methylpropanesulfonic acid and 69.5 g of a 45% solution of NMA-methylolacrylamide NMA.

In a 3-liter laboratory reactor equipped with a paddle stirrer, reflux condenser and appropriate metering devices, 1.28 kg of deionized water, 54.4 g of a 25% NaOH solution, 0.849 g of mercaptopropionic acid MPC, 112 g of solid 2- acrylamido-2-methylpropanesulfonic acid AMPK, 36.2 g of a 45% solution of N-methylolacrylamide NMA and 2.62 g of methyl methacrylate. The solution was stirred and heated to 80 ^° C. The polymerization was started by dosing into the system for 3 hours a 2.2% solution of ammonium persulfate PSA. 10 minutes after the start of the supply of the PSA solution, a metered supply of the above-described monomer solution is carried out for 2 hours. Then the polymerization is continued, completing it at a temperature of 90 ^o C. After cooling, the pH of the solution with NaOH is set to 7. The resulting clear solution contains solid material in an amount of 16.1%, has a pH = 7, a viscosity of 88 MPa • s ( Brookfield viscometer, 20 rpm) and an average molecular weight of 162,000 (GPC; sodium polystyrene sulfonate as standard), the surface tension of a 5% aqueous solution is 57.5 mN / m.

The content of monomer units, calculated taking into account 100% composition, is: AMPK 83.5 wt.%, NMA 14.5 wt.%, Methyl methacrylate 2.0 wt.%
Example 2
Preparation of approximately 16% polymer solution AMPK-NMA-ST
Preparation of the dosing solution of monomers: 459 g of water is placed in an appropriate dosing vessel and the following substances are successively dissolved: 81.5 g of a 25% NaOH solution, 0.849 g of MPC mercaptopropionic acid, 4.18 g of styrene, 180 g of 2-acrylamido-2- AMPK methylpropanesulfonic acid and 69.5 g of a 45% solution of NMA-methylolacrylamide NMA.

In a 3-liter laboratory reactor equipped with a paddle stirrer, reflux condenser and appropriate metering devices, 1.28 kg of deionized water, 54.4 g of a 25% NaOH solution, 0.849 g of mercaptopropionic acid MPC, 112 g of solid 2- acrylamido-2-methylpropanesulfonic acid AMPK, 36.2 g of a 45% solution of N-methylolacrylamide NMA and 2.62 g of styrene CT. The solution is stirred and heated to a temperature of 80 ^o C. The polymerization is started by dosing into the solution for 3 hours a 2.2% solution of ammonium persulfate PSA. 10 minutes after the start of the supply of the PSA solution, a metered supply of the above-described monomer solution is carried out for 2 hours. Then the polymerization is continued, completing it at a temperature of 90 ^o C. After cooling with NaOH, the pH of the solution is set to 7. Obtained in this way, the clear solution contains solid material in an amount of 15.8%, has a pH = 7, a viscosity of 48 MPa • s (Brookfield, 20 rpm) and an average molecular weight of 450,000 (GPC; sodium polystyrene sulfonate as standard), the surface tension of a 5% aqueous solution is 61.6 mN / m.

 The content of monomer units is: AMPK 83.5 wt.%, NMA 14.5 wt. %, styrene 2.0 wt.%.

Example 3
Preparation of approximately 16% polymer solution AMPK-NMA with hydrophobic dodecyl end groups.

 Preparation of the dosing solution of monomers: 455 g of water is placed in an appropriate dosing vessel and the following substances are successively dissolved: 80.9 g of a 25% NaOH solution, 0.843 g of MPC mercaptopropionic acid, 179 g of 2-acrylamido-2-methylpropanesulfonic acid AMPK and 68.9 g of a 45% solution of N-methylolacrylamide NMA.

 Preparation of the dosing solution of the regulator: 5.39 g of dodecyl mercaptan is dissolved in a suitable dosing vessel in 48.5 g of acetone.

In a 3-liter laboratory reactor equipped with a paddle stirrer, reflux condenser and appropriate metering devices, 1.21 kg of deionized water, 53.9 g of a 25% NaOH solution, 12.1 g of acetone, 0.843 g of mercaptropionic acid MPC are sequentially loaded 111 g of solid 2-acrylamido-2-methylpropanesulfonic acid AMPK and 36.0 g of a 45% solution of N-methylolacrylamide NMA and 1.35 g of dodecyl mercaptan. The solution was stirred and heated to a temperature of 80 ^° C. The polymerization was started by dosing into the reactor for 3 hours a 2.2% solution of ammonium persulfate PSA. 10 minutes after the start of supplying the PSA solution to the reactor, the dosed monomer solution described above and the dosed regulator solution are supplied to the reactor for 2 hours. Then the polymerization is continued, completing it at a temperature of 90 ^o C. After cooling with NaOH, the pH of the solution is set to 7. Obtained in this way a clear solution contains solid material in an amount of 16.3%, has a pH = 7, a viscosity of 49.5 MPa • c (Brookfield, 20 rpm) and an average molecular weight of 148,000 (GPC; polystyrene sulfonate sodium as standard), the surface tension of a 5% aqueous solution is 63.9 mN / m.

 The content of monomer units is: AMPK 83.1 wt.%, NMA 14.4 wt. %, dodecyl mercaptan 2.5 wt.%.

Example 4
Preparation of approximately 55% dispersion of ethylene-vinyl acetate with the polymer of Example 1 as a protective colloid.

 Preparation of the dosing solution of monomers: 633 g of vinyl acetate and 32.4 g of butyl acrylate are mixed in a dosing vessel.

 Preparation of a dosed aqueous solution: 26.6 g of deionized water are placed in a dosing vessel and 2.94 g of 2-acrylamido-2-methylpropanesulfonic acid (sodium salt, 50% aqueous solution) are successively dissolved and stirred in it, 32.8 g 48 % solution of N-methylolacrylamide, 11 g of polyglycol ether of isotridecyl alcohol, 5.52 g of acrylic acid and 91.4 g of the 16.1% aqueous polymer solution of Example 1.

In a 2 liter laboratory autoclave equipped with a stirrer and appropriate dosing devices, 521 g of deionized water, 2.77 g of a 25% solution of sodium vinyl sulfonate, 1.15 g of a 30% solution of half-ether sulfosuccinate, 10.7 g 40% ethylene oxide-propylene oxide-ethylene oxide block copolymer solution, 2.21 g of a 48% N-methylolacrylamide solution, 7.36 g of butyl acrylate and 63.3 g of vinyl acetate. After heating the contents of the autoclave to a temperature of 45 ^° C., an ethylene pressure of 60 bar is set and the polymerization is initiated using a 5% solution of ammonium persulfate and a 2.5% solution of ascorbic acid. The dosing rates of the initiators introduced are set in accordance with the total dosing time of 6 hours. An indicator of the onset of polymerization is the generation of heat due to an exothermic reaction. 10 minutes after the start of polymerization, a dosed supply of monomers and an aqueous solution of an emulsifier is started. The dosing rate in each case corresponds to a dosing time of 4 hours. Upon completion of the polymerization, the pressure in the reactor is released and a pH value of approximately 5 is set.

 The clot-free polymer dispersion obtained in this way has the following characteristics: solids content: 56.1%, pH 4.9, particle sizes approximately 440 nm, viscosity: 2980 mPa • s (Brookfield, 20 rpm), content ethylene in the polymer resin: 21.8 wt.%, the degree of crosslinking of the polymer film: 81.3%.

 The content of monomer units is: vinyl acetate 71.4 wt.%, Ethylene 22.0 wt.%, Butyl acrylate 4.1 wt.%, AMPK 0.2 wt.%, NMA 1.7 wt.%, Acrylic acid 0.5 wt.%, vinyl sulfonate 0.1 wt.%.

Example 5
Preparation of an approximately 55% polymer dispersion of ethylene-vinyl acetate with the polymer of Example 2 as a protective colloid.

 Preparation of the dosing solution of monomers: 633 g of vinyl acetate and 32.4 g of butyl acrylate are mixed in a dosing vessel.

 Preparation of a dosed aqueous solution: 42 ml of deionized water are placed in a dosing vessel and 2.94 g of 2-acrylamido-2-methylpropanesulfonic acid (sodium salt, 50% aqueous solution) are successively dissolved and stirred in it, 32.8 g of 48% - a solution of N-methylolacrylamide, 11 g of polyglycol ether of isotridecyl alcohol, 5.52 g of acrylic acid and 91.4 g of a 15.8% aqueous polymer solution from example 2.

In a 2 liter laboratory autoclave equipped with a stirrer and appropriate dosing devices, 521 g of deionized water, 2.77 g of a 25% solution of sodium vinyl sulfonate, 1.15 g of a 30% solution of half-ether sulfosuccinate, 10.7 g 40% ethylene oxide-propylene oxide-ethylene oxide block copolymer solution, 2.21 g of a 48% N-methylolacrylamide solution, 7.36 g of butyl acrylate and 63.3 g of vinyl acetate. After heating the contents of the autoclave to a temperature of 45 ^° C., the ethylene pressure is set to 60 bar and the start of polymerization is initiated using a 5% solution of ammonium persulfate and a 2.5% solution of ascorbic acid. The feed rates of the initiators are set in accordance with a total dosing time of 6 hours. An indicator of the onset of polymerization is the generation of heat due to an exothermic reaction. 10 minutes after the start of the reaction, the metering solution of monomers and an aqueous emulsifier solution are fed into the apparatus. The dosing rate in each case corresponds to a dosing time of 4 hours. Upon completion of the polymerization, the pressure in the reactor is released and a pH value of approximately 5 is set.

 The clot-free polymer suspension thus obtained has the following characteristics: solid material content: 55.2%, pH 4.8, particle sizes about 330 nm, viscosity: 5450 mPa • s (Brookfield, 20 rpm), content ethylene in the polymer resin: 17.0 wt.%, the degree of crosslinking of the polymer film: 73.1%.

 The content of monomer units is: vinyl acetate 76.0 wt.%, Ethylene 17 wt. %, butyl acrylate 4.4 wt.%, AMPK 0.2 wt.%, NMA 1.8 wt.%, acrylic acid 0.5 wt.%, vinyl sulfonate 0.1 wt.%.

Example 6
Preparation of an approximately 55% dispersion of ethylene vinyl acetate with the polymer of Example 3 as a protective colloid.

 Preparation of the dosing solution of monomers: 633 g of vinyl acetate and 32.4 butyl acrylate are mixed in a dosing vessel.

 Preparation of a dosed aqueous solution: 42 ml of deionized water is placed in a dosing vessel and 2.94 g of 2-acrylamido-2-methylpropanesulfonic acid (sodium salt, 50% aqueous solution) are dissolved and stirred in it, 32.8 g of 48% N-methylolacrylamide solution, 11 g of polyglycol ether of isotridecyl alcohol, 5.52 g of acrylic acid and 90.3 g of the 16.3% aqueous polymer solution of Example 3.

In a 2 liter laboratory autoclave equipped with a stirrer and appropriate dosing devices, 526 g of deionized water, 2.77 g of a 25% solution of sodium vinyl sulfonate, 1.15 g of a 30% solution of half-ether sulfosuccinate, 10.7 g 40% ethylene oxide-propylene oxide-ethylene oxide block copolymer solution, 2.21 g of a 48% N-methylolacrylamide solution, 7.36 g of butyl acrylate and 63.3 g of vinyl acetate. After heating the contents of the autoclave to a temperature of 45 ^o C, increase the ethylene pressure to 60 bar and initiate the start of polymerization using a 5% solution of ammonium persulfate and a 2.5% solution of ascorbic acid. The feed rates of the metered initiators are set in accordance with the total dosing time of 6 hours. An indicator of the onset of polymerization is the generation of heat due to an exothermic reaction. 10 minutes after the start of the reaction, a dosed supply of monomers and an aqueous emulsifier solution is started. Dosing rates in each case correspond to a dosing time of 4 hours. Upon completion of the polymerization, the pressure in the reactor is released and a pH value of approximately 5 is set.

 The polymer-free dispersion obtained in this way has the following characteristics: solids content: 55.1%, pH 4.8, particle sizes about 320 nm, viscosity: 5150 mPa • s (Brookfield, 20 rpm), ethylene content polymer resin: 21.6 wt.%, degree of crosslinking of the polymer film: 88.7%.

 The calculated number of monomer units is the same as in example 4.

Example 7 (comparative)
Preparation of approximately 55% dispersion of ethylene-vinyl acetate without the protective colloid according to the invention.

 The process of obtaining the dispersion was carried out in the same way as described in examples 4-6, but without the use of the protective colloid according to the invention.

 Obtained in this way, a clot-free polymer dispersion has the following characteristics: solids content: 53.9%, pH 4.7, particle size about 310 nm, viscosity: 1380 mPa • s (Brookfield, 20 rpm), ethylene content in polymer resin: 20.9 wt.%, degree of crosslinking of the polymer film: 73.7%.

 The following example illustrates the preparation of redispersible compositions of polymer powders by spray drying of an aqueous dispersion of polymers.

 Example 8

The dispersion from example 6 is mixed with 5 wt.% Polyvinyl alcohol with a degree of hydrolysis of 88 mol.% And a viscosity of 4 MPa • s. The resulting dispersion is diluted with water until a viscosity of 100-200 mPa • s is obtained, sprayed through a nozzle with pre-compressed air at a pressure of 4 bar and dried at a temperature of 100-140 ^o C. Then the resulting dried powder is mixed with 10 wt% of a substance that prevents the particles from sticking together, based on calcium or magnesium carbonate.

Technological tests
Samples of viscose staple tissue were impregnated with dispersions of the polymers of examples 4-7, squeezed, and then dried for 3 minutes at a temperature of 150 ^o C (binder content of 29.5%). The strength of the tissue samples processed in this way was tested in the transverse direction. The tests were carried out with dried samples, respectively, after they were kept for one minute in water or in isopropanol. For this purpose, three strips of the specified fabric were laid on top of each other with a length of 150 mm and a width of 15 mm each, and they were jointly tested. The measurement conditions were as follows: clamping length 100 mm, clamping width 15 mm, measuring speed 100 mm / min. The measured value was the value of the ultimate tensile force, i.e. maximum tensile force achieved during measurements. The test results are shown in the table.

 As clearly follows from the test results using dispersions from examples 4-6, on the one hand, and using the dispersion from example 7 (comparative - without the use of polyelectrolyte protective colloids according to the invention), on the other hand, crosslinkable protective colloids according to the invention are crosslinkable ethylene vinyl acetate copolymers exhibit significantly higher water and solvent resistance compared to the crosslinkable ethylene vinyl acetate copolymers synthesized by t traditional technology.

Claims (11)

 1. Water-soluble crosslinkable protective colloids for aqueous dispersions of polymers having a molecular weight of less than 500,000 containing. a) at least 20 weight. % monomer units containing sulfonic acid or sulfonate groups, b) 4-80 wt.% monomer units containing N-methylol or N-alkoxymethyl groups, c) 0.1-20 wt.% hydrophobic monomer units from the group insoluble in water of ethylenically unsaturated compounds and hydrophobic end groups of residues of initiators or regulatory molecules, and the amounts expressed in wt.% are indicated relative to the total weight of the copolymer, and moreover, part of the monomer units containing sulfonic acid / sulfonate groups, if necessary, up to 50 wt.% in feather counting by weight of the monomer units a) may be replaced by monomeric units d) containing carboxyl groups, or monomeric units e) containing amide groups.  2. The water-soluble crosslinkable protective colloids according to claim 1, characterized in that they contain: a) 70-87 wt.% Monomer units containing sulfonic acid or sulfonate groups, b) 12-25 wt.% Of monomer units containing N-methylol - or N-alkoxymethyl groups, c) 1-5 wt.% hydrophobic monomer units from the group of water-insoluble ethylenically unsaturated compounds.  3. The water-soluble crosslinkable protective colloids according to claim 1 or 2, characterized in that as the monomer units a) they contain 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, sulfopropyl ether of acrylic acid, sulfopropyl ether of itaconic acid, vinyl sulfonic acid or their ammonium salts sodium, potassium and calcium; as monomer units b) contain N-methylolacrylamide, N-methylol methacrylamide, N- (isobutoxymethyl) acrylamide, N- (isobutoxymethyl) methacrylamide or N- (n-butoxymethyl) acrylamide, and as monomer units c) contain methyl methacrylate, vinyl propionate, isopropenyl acetate, vinyl laurate or vinyl ester of α-branched monocarboxylic acids with 5-10 carbon atoms.  4. The method of obtaining stabilized by protective colloids of aqueous dispersions of polymers by radical polymerization of ethylenically unsaturated monomers by the method of suspension or emulsion polymerization, characterized in that the polymerization is carried out in the presence of at least one crosslinkable protective colloid according to any one of claims 1 to 3.  5. The method according to claim 4, characterized in that the polymerization is carried out by the method of emulsion polymerization in the presence of one or more monomers from the group of vinyl esters of unbranched or branched carboxylic acids with 1-18 carbon atoms, esters of acrylic acid and methacrylic acid with unbranched or branched alcohols with 1-18 carbon atoms, vinyl aromatic compounds, vinyl halides and olefins.  6. Aqueous polymer dispersions of polymers of ethylenically unsaturated monomers that contain 0.1-20 wt.% Of one or more protective colloids according to claims 1-3, based on the amount of solid material in the polymer. 7. Aqueous dispersions of polymers according to claim 6, characterized in that they contain one or more polymers based on vinyl esters or polymers based on (meth) acrylic acid esters, which, based on the total weight of the polymers, do not necessarily contain another 0.5-5 , 0 wt.% Comonomer units with a crosslinking action from the group consisting of N-methylacrylamide, N-methylol methacrylamide, N- (alkoxymethyl) acrylamides or N- (alkoxymethyl) methacrylamides with a C ₁ -C ₆ alkyl residue.  8. Aqueous dispersions of polymers according to claim 7, characterized in that they contain a copolymer of vinyl acetate and ethylene with an ethylene content of from 5 to 50 wt.% And a content of from 0.5 to 5.0 wt.% Of one or more comonomers from the group, including N-methylolacrylamide, N-methylol methacrylamide, N- (iso-butoxymethyl) acrylamide, N- (isobutoxymethyl) methacrylamide, N- (n-butoxymethyl) acrylamide, N- (n-butoxymethyl) methacrylamide.  9. Aqueous dispersions of polymers according to claims 6-8, used as binders for coatings, plasters and paints, in particular pigmented paints and varnishes; as adhesives and binders for wood, paper, textiles and non-woven materials; as binders in the manufacture of paper and the manufacture of press materials and molded products; as binders for use in the construction industry, in particular as additives to concrete, building adhesives, mortar, putty and filling masses.  10. Redispersible in water compositions of polymer powders obtained by spray drying of an aqueous dispersion of polymers according to claims 6-8.  11. Redispersible compositions of polymer powders according to claim 10, used as binders for coatings, plasters and paints, in particular pigmented paints and varnishes; as adhesives and binders for wood, paper, textiles and non-woven materials; as binders in the manufacture of paper and the manufacture of press materials and molded products; as binders for use in the construction industry, in particular as additives to concrete, building adhesives, mortar, putty and filling masses.

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