EP2601227A1

EP2601227A1 - Process for preparing vinyl acetate-ethylene copolymers by means of emulsion polymerization

Info

Publication number: EP2601227A1
Application number: EP11745513.9A
Authority: EP
Inventors: Helmut Zecha; Gerhard KÖGLER
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2010-08-02
Filing date: 2011-07-25
Publication date: 2013-06-12
Also published as: US20130131261A1; DE102010038788A1; CN103140514A; WO2012016869A1

Abstract

The invention provides processes for preparing vinyl acetate-ethylene copolymers by means of free-radical initiated emulsion polymerization of vinyl acetate, ethylene and optionally one or more further comonomers in the presence of at least one protective colloid and optionally at least one emulsifier, characterized in that the vinyl acetate-ethylene copolymers contain 18 to 45% by weight of ethylene units, based on the total weight of the vinyl acetate-ethylene copolymers, and at least 70% by weight of ethylene units, based on the total weight of the ethylene units and of the further comonomer units of the vinyl acetate-ethylene copolymers, and the free-radical initiated emulsion polymerization is performed in the presence of A) 0.5 to 20% by weight, based on the total weight of the monomers used overall, of one or more solvents, or B) 0.1 to 20% by weight, based on the total weight of monomers used overall, of one or more solvents, and 0.5 to 4% by weight, based on the total weight of monomers used overall, of one or more anionic sulphosuccinic esters of the general formula R¹O-CO-CH₂-CH (SO₃M) -CO-O-R¹ (I) in which M is a cation, R¹ is a linear or branched alkyl radical having 4 to 17 carbon atoms, an alkylene oxide group -(R²-O)_n-X or a cation M, where R² is a linear or branched alkylene unit having 2 to 5 carbon atoms, n is an integer from 2 to 20 and X is a linear or branched alkyl radical having 4 to 17 carbon atoms, where at most one R¹ radical in the general formula (I) is a cation M.

Description

Process for the preparation of vinyl acetate-ethylene copolymers by emulsion polymerization

The invention relates to processes for the preparation of inylacetate-ethylene copolymers by means of emulsion polymerization, the vinyl acetate-ethylene copolymers obtainable in this way and their use in adhesives, in particular for the bonding of polymer substrates with cellulosic materials. Methods of emulsion polymerization of vinyl acetate with ethylene, optionally with further comonomers, in the aqueous phase for the preparation of polymer dispersions, have long been known. To achieve colloidal stability of the dispersions prepared in this way, water-soluble polymers, for example polyvinyl alcohols, cellulose derivatives or polyvinylpyrrolidone, are used as so-called protective colloids and / or low molecular weight surface-active substances, so-called emulsifiers or surfactants. For example, DE-OS 1595402 describes processes in which at least 75% of the vinyl acetate monomer is initially charged in order to improve the ethylene incorporation rate into vinyl acetate-ethylene copolymers and is polymerized in the presence of emulsifiers. In order to ensure a uniform course of polymerization it is recommended in DE-OS 2112769 to use a redox initiator system in the copolymerization of vinyl esters with ethylene, to completely introduce the reducing agent with the vinyl ester fraction, the ethylene and the dispersants and to meter in only the oxidation component. Polymerization is carried out in the presence of polyvinyl alcohol and / or emulsifiers. US Pat. No. 3,644,262 describes processes having an improved rate of incorporation of ethylene into vinyl acetate-ethylene polymers, in which the vinyl acetate content and the emulsifier and / or protective colloid content are completely metered or only charged to very small proportions. This process allows up to about 20% ethylene to be incorporated into the copolymer at low pressures and temperatures. The aqueous polymer dispersions based on vinyl acetate and ethylene (VAE dispersions) which are obtainable in this way are used, for example, as binders, in particular for adhesives, paints or fibers. Fleece weave, used.

However, the property profile requirements of such VAE dispersions have become more and more specific over the years. For example, adhesives are becoming increasingly demanding for bonding materials with low surface energy, for example when bonding polymer films with cellulosic materials, such as paper or cardboard. Common VAE dispersions, such as, for example, the products according to DE-OS 1595402 or US Pat. No. 3,644,262, are unsuitable for this purpose because they cause too little adhesion of the adhesive bond. Therefore, various attempts have been made to provide VAE dispersions with improved adhesion.

US-A-3,708,388 discloses vinyl acetate-ethylene copolymer based adhesives stabilized with alkylphenol ethoxylate emulsifiers and optionally protective colloids and having a defined Intrinsic Viscosity and can be used to lamination of films. At least 75% of the vinyl acetate is used in the preparation. To improve the mechanical strength at high temperatures, the use of crosslinking agents is recommended.

EP 1212383 A1 describes processes for the preparation of adhesives with improved adhesion by preparing aqueous polymer dispersions by means of emulsion polymerization and, after the polymerization has ended, with emulsifiers. EP 1212383 A1 teaches that an improvement in the adhesion only occurs with subsequent addition of the emulsifiers, whereas the use of emulsifiers during the polymerization does not lead to an improvement in the adhesion. Disadvantageously, no adhesives having a property level with high cohesion and high adhesion are accessible with products according to EP 1212383 A1; For example, the adhesion to polyester films is too low and the setting speed of the dispersions too low. EP 890625 A1 describes vinyl acetate-ethylene polymer dispersions which fulfill certain values for a storage modulus of the polymer and are recommended as an adhesive for hard-to-bond top surfaces, such as polyethylene, polyester, metallized polyester and oriented polypropylene. For the preparation of the polymer dispersions, the use of regulators is recommended and in the polymerization process, less than 15% of the vinyl acetate is initially charged in the reactor charge, and the vinyl acetate content during the polymerization is kept below 5%. Polymer dispersions obtainable in this way have a high adhesion to difficult to bond polymer films. Unfortunately, the cohesion of the adhesive film is too low. In addition, alkylphenol ethoxylates having 4 to 100 ethylene oxide units are used as nonionic emulsifiers. However, such emulsifiers are frowned upon because of their environmental and health impact.

EP 385734 A1 recommends certain vinyl acetate-ethylene polymers for adhesives having high setting rates. To prepare the vinyl acetate-ethylene copolymers, mixtures of partially hydrolyzed polyvinyl alcohols and nonionic polyoxyethylene emulsifiers with defined HLB are used. Characteristic of the polymerization process is that 40 to 90 wt .-% of the vinyl acetate are emulsified in an aqueous solution containing the total amounts of polyvinyl alcohols, emulsifiers and reducing agent, so that a stable emulsion is formed and then after pressing ethylene, the remaining 10 be dosed to 60 wt .-% of vinyl acetate. Disadvantageously, this procedure also does not lead to copolymers having a property level with high cohesion and high adhesion; Adhesion to polyester films is too low.

In US 5571860 it is proposed to copolymerize to improve the setting rate, heat resistance and adhesion of adhesives based on vinyl acetate-ethylene copolymers, N-vinylformamide or N-vinylpyrrolidone. The heat resistance is further improved by using from 0.5 to 10% by weight of crosslinkable monomer such as glycidyl methacrylate. In the manufacture Development of the copolymers, 70% of the vinyl acetate used together with 90% of the dispersants used in the reactor and the remainder dosed. The dispersants used are polyvinyl alcohols, optionally mixed with nonionic alkylphenol ethoxylate emulsifier. The copolymerization of N-vinylformamide or N-vinylpyrrolidone requires disadvantageously high polymerization temperatures and thus relatively high pressures, and the incorporation of ethylene is difficult. Another disadvantage is the use of alkylphenol ethoxylates as emulsifiers.

EP 279384 A1 describes vinyl acetate-ethylene polymer dispersions which are suitable as packaging adhesives and teaches that a combination of low molecular weight polyvinyl alcohols and nonionic emulsifiers to stabilize the dispersion additionally improves the setting speed of the adhesive even at high solids content. During the polymerization, the low molecular weight polyvinyl alcohol is initially charged at least partially and the emulsifier fraction is completely introduced. However, so available products cause too little adhesion between cellulosic materials and polyester films.

GB-A 1546275 describes vinyl acetate-ethylene polymer dispersions which, when used as pressure-sensitive adhesives, have a good balance of tack, cohesion and adhesion. As the examples using only hydroxyethylcellulose as the protective colloid and nonionic emulsifier and the comparative examples show, to achieve good adhesion, the use of chain regulators and a protective colloid content of not more than 1% by weight, based on the total monomer, are required. GB-A 1546275 also calls for intrinsic viscosity numbers between 0.6 and 1.0 dl / g. Although the products thus obtained have good adhesion properties, it is disadvantageous that the cohesion is too low and the setting speed too low.

US Pat. No. 4,269,090 deals with adhesives which improve the wettability of polyvinyl chloride substrates and the setting speed with simultaneously high cohesion. For this purpose, US Pat. No. 4,269,090 recommends vinyl acetate-ethylene polymer dispersions obtained by using defined amounts of preferably nonionic emulsifiers the. However, the polymers obtainable in this way can not satisfy a property level with high cohesion and high adhesion, since the adhesion values for polyester films are too low.

US-A-3769151 is concerned with providing vinyl acetate-ethylene copolymer dispersion based adhesives having improved adhesive properties, particularly to vinyl polymers, while improving thickening response. Described is a complex process of seed emulsion polymerization of vinyl acetate, 5 to 20 wt .-% of ethylene in the copolymer and 0.01 to 1 wt .-% of unsaturated acids, using a mixture of partially hydrolyzed and vollverseiften polyvinyl alcohols, wherein for the preparation of the Seeds only partially saponified polyvinyl alcohol, and in the seed polymerization, a blend with higher-saponified polyvinyl alcohol is used. Nonionic, cationic or anionic emulsifiers have no influence on the adhesive and cohesive properties of the vinyl acetate-ethylene copolymer dispersions. In Examples, the emulsion polymerization is carried out in the presence of polyvinyl alcohol and anionic emulsifier Aerosol MA, a diester of sulfosuccinic acid having 6 C atoms in the alkyl radical, or in the presence of nonionic nonylphenol ethoxylate, or nonionic ethylene oxide-propylene oxide block copolymer or unsaturated nonionic ethoxylated emulsifier. To evaluate the adhesive properties, US-A 3,769,151 describes a "not vinyl adhesion test" for determining a "creep resistance" time, which essentially characterizes the cohesion. Although aqueous polymers according to US Pat. No. 3,769,151 have a high cohesion, the adhesion to polymer substrates, in particular to polyesters, is too low, so that no property level with high cohesion and high adhesion is achieved.

DE-A 102009001097 describes protective colloid- and emulsifier-stabilized dispersions of vinyl acetate-ethylene polymers and their use in adhesives, the emulsifiers being nonionic emulsifiers, optionally in combination with small amounts of anionic emulsifiers. DE-A 102009001097 discloses ethylene-vinyl acetate copolymers which are prepared by means of emulsion polymerization in the presence of protective colloids and selected nonionic emulsifiers and, when used as or in adhesives, exhibit a so-called balanced adhesion cohesion balance of the ethylene-vinyl acetate copolymers ,

The prior art thus provides vinyl acetate-ethylene copolymers which, when used in adhesives, either have a high cohesion of the adhesive film or a high adhesion of the adhesive film to polymer substrates, but can not achieve a property level with high cohesion and high adhesion. Usually, such vinyl acetate-ethylene copolymers in the presence of

Protective colloids stabilized, mostly polyvinyl alcohol is used. With regard to the amount of protective colloid used, it is known from GB-A 1546275 that proportions of more than 1% by weight, based on monomer, adversely affect the adhesion. Emulsifiers are often used for additional stabilization of the polymer particles. Nonionic emulsifiers, in particular alkylphenol ethoxylates, are frequently used, whereas according to GB-A 1546275 the use of anionic emulsifiers is disadvantageous. According to EP 1212383 Al and US 3769151, the use of emulsifiers during the emulsion polymerization does not affect the adhesive properties of the products. However, it is known from EP 1212383 Al that the subsequent addition of emulsifiers to a polyvinyl alcohol-stabilized dispersion can improve the adhesion.

It is an object of the present invention to provide aqueous dispersions of vinyl acetate-ethylene mixed polyisocyanates and processes for their preparation, with which the abovementioned disadvantages of known aqueous dispersions of vinyl acetate-ethylene copolymers with respect to insufficient adhesion of the adhesive film produced therefrom difficult to bond substrates, such as polymer substrates, in particular to polyester or polystyrene, overcome and at the same time the disadvantages of known polymers are eliminated with respect to low cohesion and overall a property level with high cohesion and high adhesion is achieved. Adhesion is understood to mean the adhesion between a substrate and an adhesive film produced from an aqueous dispersion of a vinyl acetate-ethylene copolymer. Cohesion refers to the cohesion within the adhesive film produced from an aqueous dispersion of a vinyl acetate-ethylene copolymer.

The minimum requirements for a property level with high cohesion and high adhesion of an adhesive can be quantified by the following parameters, according to which the adhesive preferably has an adhesive film with a cohesion, measured as heat resistance, of at least 0.2 N / mm ² , preferably at least 0.4 N / mm ² , and preferably simultaneously fulfilling the following adhesion parameters:

(i) Adh PS is preferably at least 3.8 N / cm, where Adh PS is the peel strength, that is an adhesive bond made of cotton and polystyrene Silveraplex® Polyflex 90 (PS film) at a peel rate of 5 mm / min;

(ii) Adh PET1 is preferably at least 3.4 N / cm, with Adh

PET1 is the peel strength exhibited by an adhesive-bonded composite of cotton and Hostaphan® RN125 polyethylene terephthalate film (PET film) at a peel rate of 10 mm / min; and

(iii) Adh PET2 is preferably at least 1.2 N / cm, PET2 being the peel strength, and the cotton-bonded and polyethylene terephthalate film Hostaphan® RN125 (PET film) being made by adhesive bonding at a peel rate of 900 mm / min.

The minimum requirements for a property level with high cohesion and high adhesion of an adhesive further include that it satisfies a liability sum, HS, of HS preferably 18, in particular HS ≦ 17.

Furthermore, adhesive films of aqueous dispersions of vinyl acetate-ethylene copolymers should have a high setting speed of, that is to say in particular, a tightening speed. speed (AZG) of preferably 3.0 seconds or less.

The individual methods, conditions and materials for determining the aforementioned parameters concerning cohesion, adhesion, adhesion sum or tightening speed are described in detail below under the heading "Test Methods for Determining Adhesive Properties." Finally, the aqueous dispersions of vinyl acetate-ethylene If possible, in the preparation of the vinyl acetate-ethylene copolymers, the use of chain regulators, also known as chain transfer agents, in particular of aldehydes, should be used. and mercapto compounds, on seed latex, on the use of alkylphenol ethoxylates (APEO) or on vinyl chloride monomer as a comonomer Surprisingly, the objects were in particular due to the synergistic interaction of ethylene content of vinyl acetate-ethylene copolymers and the use of solvents, in particular alkyl alcohols, and optionally certain amounts of special anionic sulfosuccinic dissolved in the emulsion polymerization for the preparation of vinyl acetate-ethylene copolymers.

The addition of solvents to emulsion polymers to improve performance properties is known. For example, GB81625, GB682773 and GB895153 describe the addition of methanol, ethanol, ethylene glycol, glycerol, acetone or methyl acetate as an antifreezing agent, for example when carrying out polymerizations below 0 ° C. In GB1018448 it is stated that acrylate dispersible by the addition of methanol, ethanol or isopropanol can be coagulated after synthesis to separate the polymers; the same also in GB548356 and in GB601807. In GB 928209 and GB1116509 Alcohols, such as methanol or ethanol, used for the purification of polymers. GB621467 describes the emulsion polymerization of conjugated diene compounds, such as butadiene, optionally with styrene or chlorinated styrene in an aqueous, alcoholic medium. GB573366 mentions the utility of water / ethanol mixtures as a medium for vinyl chloride emulsion polymerization to increase VC solubility in the aqueous phase. US Pat. No. 4,708,139 describes the emulsion polymerization of cationic latices (acrylates / amino group-modified acrylates) in water / alcohol mixtures to improve colloidal stability and to reduce particle aggregation processes and to improve the mechanical stability of the dispersions. As solvents, mention may be made of alcohols, glycols, esters, cyclic ethers, hydroxylated ethers. DE1123470 describes the use of special cationic surfactants and solvents, such as methanol or hexylene glycol, in the emulsion polymerization of vinyl esters.

R0116556 describes vinyl acetate / acrylate emulsion polymerizations in the presence of anionic and nonionic emulsifiers and coalescing aids from the group acetone or ethanol. JP11209430 describes the emulsion polymerization of {meth) acrylates in the presence of cyclic organic phosphates in water / alcohol mixtures. No. 3,577,376 describes the emulsion polymerization of vinyl acetate and acrylamide, wherein alkyl alcohols, in particular methanol, but also ethanol, i-propanol and t-butanol, and also other solvents such as formamide, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, as "solubilizing agents" for solution DE2512589 describes self-crosslinking vinyl acetate-ethylene copolymers consisting of ethylene, vinyl acetate, a copolymerisable N-methylol compound, (meth) acrylic acid radicals (n), an unsaturated carboxylic acid and polyunsaturated monomers. Dispersants In example 8 of DE 2512589, a polymerization is carried out in the absence of protective colloid in the presence of methanol, in which case methanol can counteract the formation of coarse particulates (sieve residue) DE 1770395 relates to binders for pigments and fillers for paints so as additional

Binder for mortar and describes the preparation of terpolymers by means of emulsion polymerization of vinyl chloride, vinyl esters and ethylene in the presence of protective colloids, nonionic emulsifiers tors as well as solvating agents, such as plasticizers or solvents. The weight ratio of vinyl chloride to ethylene is 1: 2 to 3: 1. With the hitherto known use of solvents in emulsion polymerization, a very wide variety of objectives are pursued; in particular, solvents serve, for example, as "antifreezing agents", to improve colloidal stability and to avoid particle aggregation processes, such as the formation of sieve residue or to improve shear stability However, vinyl acetate (co) polymers obtained in the presence of solvents, as described in DE1123470, DE2512589 and DE1770395, are used as adhesives for bonding, for example, cellulosic materials, such as paper or paperboard, with polymer substrates, in particular with polystyrene and polyester films not suitable because they do not cause sufficient adhesion and / or sufficient cohesion.

The invention relates to processes for the preparation of vinyl acetate-ethylene copolymers by free-radically initiated emulsion polymerization of vinyl acetate, ethylene and optionally one or more other comonomers in the presence of at least one protective colloid and optionally at least one emulsifier, characterized in that

the vinyl acetate-ethylene copolymers 18 to 45 wt .-% of ethylene len units, based on the total weight of the vinyl acetate-ethylene copolymers, and

at least 70% by weight of ethylene units, based on the total weight of the ethylene units and of the further comonomer units of the vinyl acetate-ethylene copolymers, and

the free-radically initiated emulsion polymerization in the presence of

A) 0.5 to 20% by weight, based on the total weight of the total monomers used, of one or more solvents, or

B) 0.1 to 20 wt .-%, based on the total weight of the total monomers used, of one or more solvents and 0.5 to 4 wt .-%, based on the total weight of the total monomers used, at one or more anionic sulfosuccinic acid esters of the general formula

R ¹ -O-CO-CH ₂ -CH (SO ₃ M) -CO-OR ¹ (I) in which

M a cation,

R ^{1 is} a linear or branched alkyl radical having 4 to 17 C atoms, an alkylene oxide group - {R ^z -O) _n -X or a cation M, where

R ^{2 is} a linear or branched alkylene unit having 2 to 5 C atoms,

n is equal to an integer value of 2 to 20 and

X is a linear or branched alkyl radical having 4 to 17 C atoms,

wherein in the general formula (I) at most one radical R ^{1 is} a cation M.

Another object of the invention are vinyl acetate-ethylene copolymers obtainable by free-radically initiated emulsion polymerization of vinyl acetate, ethylene and optionally one or more other comonomers in the presence of at least one protective colloid and optionally at least one emulsifier, characterized in that

at least 70 wt .-% of ethylene units, based on the total weight of the ethylene units and the other comonomer units of vinyl acetate-ethylene copolymers, and contain

the vinyl acetate-ethylene copolymers are obtainable by free-radically initiated emulsion polymerization in the presence of

A) 0.5 to 20 wt .-%, based on the total weight of the total monomers used, of one or more solvents, or B) 0.1 to 20 wt .-%, based on the total weight of the total monomers used, on one or more solvents and

0.5 to 4 wt .-%, based on the total weight of the total monomers used, of one or more anionic sulfosuccinic acid esters of the general formula

R ^{1 is} -O-CO-CH ₂ -CH (SO ₃ ) -CO-OR ¹ (I)

in which

M a cation, R ^{1 is} a linear or branched alkyl radical having 4 to 17 C atoms, an alkylene oxide group - (R ² -O) _n -X or a cation M, where

R ^{2 is} a linear or branched alkylene unit having 2 to 5 C atoms,

n is equal to an integer value of 2 to 20 and

X is a linear or branched alkyl radical having 4 to 17

C atoms is,

wherein in the general formula (I) at most one radical R ^{1 is} a cation M.

The individual radicals X, R ¹ and R ² and M and the parameter n of the general formula (I) can each independently assume their meaning. The abbreviation C-Atom stands for a carbon atom. The anionic sulfosuccinic acid esters of the general formula (I) are a special embodiment of anionic emulsifiers. The term monomers stands for ethylenically unsaturated compounds and includes vinyl acetate, ethylene and the optionally present further comonomers and auxiliary monomers.

In the following, the embodiments of the present invention in which one or more anionic sulfosuccinic acid esters of the general formula I are compulsorily used are designated as alternative B). The other embodiments which do not require the use of the abovementioned sulfosuccinic esters are referred to below as alternative A).

Ethylene or ethylene units have the chemical empirical formula C ₂ H ₄ . The proportion of ethylene units in the vinyl acetate-ethylene copolymers is preferably from 19 to 40% by weight, more preferably from 20 to 35% by weight, and most preferably from 22 to 32% by weight, based in each case on the total weight the vinyl acetate-ethylene copolymers. In general, the proportion of vinyl acetate units in the

Vinyl acetate-ethylene copolymers 60 to 81 wt .-%, preferably 65 to 80 wt .-%, particularly preferably 68 to 78 wt .-%, and am Most preferably 68 to 76 wt .-%, each based on the total weight of the vinyl acetate-ethylene copolymers.

In addition to vinyl acetate and ethylene, further comonomers may optionally be used in the emulsion polymerization. Examples of other comonomers are vinyl esters of carboxylic acids having 3 to 18 carbon atoms. Preferred vinyl esters are vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of α-branched monocarboxylic acids having 9 to 11 C atoms, for example VeoVa9® or VeoValO® (trade names of Hexion ). Suitable further comonomers are also those from the group of esters of acrylic acid or methacrylic acid of unbranched or branched alcohols having 1 to 15 carbon atoms. Preferred methacrylic esters or acrylic esters are esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Suitable comonomers are also vinyl halides such as vinyl chloride, or vinyl aromatics such as styrene, or olefins such as propylene.

The further comonomers are preferably used at 1 to 19% by weight and more preferably at 2 to 15% by weight and most preferably 2 to 10% by weight, based in each case on the total amount of vinyl acetate and ethylene.

Optionally, in the emulsion polymerization additionally 0.05 to 10 wt .-%, preferably 0.05 to 5 wt .-%, based on the total amount of vinyl acetate and ethylene, auxiliary monomers are used. Examples of Hilfsmonoraere are ethylenically unsaturated mono- and dicarboxylic acids, preferably acrylic acid, methacrylic acid,

Fumaric acid and maleic acid; ethylenically unsaturated carboxylic acid amides and nitriles, preferably acrylamide and acrylonitrile; Mono- and diesters of fumaric acid and maleic acid, such as diethyl and diisopropyl esters, and also maleic anhydride, ethylenically unsaturated sulfonic acids or salts thereof, preferably vinylsulfonic acid, 2-

Acrylamido-2-methylpropanesulfonic acid. Further examples are precrosslinking comonomers such as polyethylenically unsaturated comonomers, for example divinyl adipate, diallyl maleate, allyl acrylate or triallyl cyanurate, or post-crosslinking comonomers, for example acrylamidoglycolic acid (AGA), methylacrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallyl carbamate, alkyl ethers such as the isobutoxy ether or esters of N-methylolacrylamide, N-Methylolmethacrylamids and N-Methylolallylcarbamats. Also suitable are epoxide-functional comonomers such as glycidyl methacrylate and glycidyl acrylate. Further examples are silicon-functional comonomers, such as acryloxypropyltri (alkoxy) - and methacryloxypropyltri (alkoxy) silanes, vinyltrialkoxysilanes and vinylmethyldialkoxysilanes, where as alkoxy groups, for example, methoxy, ethoxy and ethoxypropylene glycol ether radicals may be present. Mention may also be made of monomers having hydroxyl or CO groups, for example methacrylic acid and acrylic acid hydroxyalkyl esters, such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and also compounds such as diacetone acrylamide and acetoacetoxyethyl acrylate or methacrylate.

Preferably, no N-vinylformamide and / or N-vinylpyrrolidone is copolymerized. It is also preferable not to copolymerize acrylonitrile and / or vinyl halide such as vinyl chloride.

The proportion of ethylene units in the vinyl acetate-ethylene copolymers is preferably at least 80% by weight, more preferably at least 90% by weight and most preferably at least 95% by weight, based on the total weight of the ethylene units , the further comonomer units and optionally the auxiliary monomer units of the vinyl acetate-ethylene copolymers.

Most preferred are vinyl acetate-ethylene copolymers which contain no units of further comonomers and / or no units of auxiliary monomers.

The polymerization takes place after the emulsion polymerization process in an aqueous medium, wherein the polymerization temperature is generally 40 ° C to 100 ° C, preferably 50 ° C to 90 ° C and in particular 60 ° C to 80 ° C. The polymerization pressure is generally between 40 and 100 bar, preferably between 45 and 90 bar, and most preferably between 45 and 85 bar. The initiation of the polymerization is preferably carried out with the customary for the emulsion polymerization redox initiator combinations.

Examples of suitable oxidation initiators are the sodium, potassium and ammonium salts of peroxodisulfuric acid, hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide, potassium peroxodiphosphate, t-butyl peroxypivalate, cumene hydroperoxide, isopropylbenzene monohydroperoxide, azobisisobutyronitrile. Preference is given to the sodium, potassium and ammonium salts of peroxodisulfuric acid and hydrogen peroxide. The initiators mentioned are generally used in an amount of 0.05 to 2.0 wt .-%, based on the total weight of the monomers.

Suitable reducing agents are the sulfites and bisulfites of the alkali metals and ammonium, for example sodium sulfite, the derivatives of sulfoxylic acid such as zinc or Alkaliformaldehydsulfoxylate, for example, sodium formaldehyde sulfoxylate (Brüggolit®) and formaldehyde derivatives of sulfinic acid and mixtures thereof known under the trade name Brüggolit® FF6 and (Iso) ascorbic acid and tartaric acid. Preference is given to Brüggolit®, Brüggolit® FF6, (iso) ascorbic acid and its salts, e.g. Na isoascorbate, and tartaric acid. The amount of reducing agent is preferably 0.05 to 3 wt .-%, based on the total weight of the monomers.

Among others, the redox-initiator combination of hydrogen peroxide and Brüggolit® or Brüggolit® FF6 is preferred. In this case, hydrogen peroxide is generally used in an amount of from 0.06 to 0.4% by weight, preferably from 0.1 to 0.3% by weight, more preferably from 0.15 to 0.25% by weight, based on the total monomer used. The ratio of oxidizing agent to reducing agent is then generally from 10 to 70 to 10 to 3, preferably from 10 to 60 to 10 to 6, and most preferably from 10 to 60 to 10 to 10 parts by weight. In particular, it may be advantageous to reduce the molar ratio of reducing agent (Red) to oxidizing agent (Ox) to values Red / Ox ≦ 1.0, preferably to values Red / Ox ≦ 0.8 and particularly preferably to values Red / Ox ≦ 0, 5 to adjust. Preferred protective colloids are partially hydrolyzed or fully hydrolyzed polyvinyl alcohols, so-called standard polyvinyl alcohols, having an average degree of hydrolysis of from 85 to 99.9 mol. On the one hand, preference is given to partially saponified standard polyvinyl alcohols or mixtures of such polyvinyl alcohols having an average degree of hydrolysis of from 86 to 96 mol%. Particular preference is given to partially saponified polyvinyl alcohols having an average degree of hydrolysis of from 86 to 90 mol%, preferably in each case having a mass-average degree of polymerization of from 600 to 2000. In order to adjust the viscosity of the resulting polymer dispersion, it may be advantageous to use mixtures of polyvinyl alcohols with a different degree of polymerization, wherein the degrees of polymerization of the individual components may be smaller or larger than the mass-average degree of polymerization of 600 to 2000 of the mixture.

On the other hand, fully hydrolyzed standard polyvinyl alcohols having an average degree of hydrolysis of from 96.1 to 99.9 mol%, preferably having an average degree of hydrolysis of from 97.5 to 99.5 mol%, alone or in mixtures with partially hydrolyzed standard polyvinyls are preferred. nylalkoholen, wherein the fully hydrolysed polyvinyl alcohols are preferably characterized by a mass-average degree of polymerization of 600 to 3500. However, it is also possible in addition to such standard polyvinyl alcohols modified polyvinyl alcohols, such as those bearing functional groups, such as acetoacetyl groups, or those containing comonomer units, such as vinyl laurate-modified or Versatic acid vinyl ester modified polyvinyl alcohols, or - and preferably - ethylene-modified polyvinyl alcohols, which are known for example under the trade name EXCEVAL®, alone or in combination with said standard polyvinyl alcohols, use. Preferred ethylene-modified polyvinyl alcohols have an ethylene content of up to 12 mol%, preferably 1 to 7 mol% and particularly preferably 2 to 6 mol%; in particular 2 to 4 mol%. The mass-average degree of polymerization is in each case from 500 to 5000, preferably 2000 to 4500, and particularly preferably 3000 to 4000. The average degree of hydrolysis is generally greater than 92 mol%, preferably 94.5 to 99.9 mole%, and more preferably 98.1 to 99.5 mole%. Of course, it is also possible and optionally advantageous to use mixtures of different ethylene-modified polyvinyl alcohols, alone or in combination with partially hydrolyzed and / or fully saponified standard polyvinyl alcohols.

Suitable protective colloids are also water-soluble cellulose derivatives, for example and preferably hydroxyethyl cellulose, having viscosities in 2% strength by weight aqueous solutions of ≦ 6500 mPas, preferably ≦ 3500 mPas, more preferably ≦ 1500 mPas and in particular ≦ 500 mPas.

Suitable protective colloids are furthermore polyvinylpyrrolidones having cuvettes between 10 and 30.

It may also be advantageous to use mixtures of said polyvinyl alcohols with water-soluble cellulose derivatives and / or polyvinylpyrrolidones or mixtures of water-soluble cellulose derivatives and polyvinylpyrrolidones. Water-soluble means that their solubility in water under normal conditions is> 1 g / 100 ml of water.

The protective colloids are generally in an amount of 1 to 7 wt .-%, preferably 1.5 to 5.5 wt .-%, particularly preferably 2 to 4 wt .-%, and in particular 2 to 3.5 wt. -%, in each case based on the total weight of the monomers, during the polymerization.

The protective colloids, in particular the polyvinyl alcohols, may be in the form of starting materials which, in addition to one or more protective colloids, contain a proportion of one or more solvents, in particular alkyl alcohols, such as methanol. The starting materials preferably contain a proportion of solvents of from 0.1 to 3% by weight, preferably from 0.1 to 2.6% by weight, more preferably from 0.1 to 2.0% by weight, and most preferably 0, 1 to 1% by weight, based in each case on the total mass of the starting material. The protective colloids, in particular the polyvinyl alcohols, are generally used in the form of starting materials which have up to a maximum of 5% by weight of volatile organic compounds conditions of organic substances and residual moisture, such as water, based on the total mass of the starting materials. The in these

Feedstocks in addition to protective colloids other ingredients are often included in commercially available protective colloids as impurities.

An essential aspect of the present invention is the performance of the emulsion polymerization in the presence of one or more solvents. The solvents generally give a solution with water and / or vinyl acetate. A solution is a single-phase, homogeneous mixture of at least two different substances and is under normal conditions according to DIN50014 in the form of a liquid. Preferably, the solvent is more than 2 g, in particular more than 10 g in 100 g of water and / or in 100 g of vinyl acetate under normal conditions according to DIN50014 soluble.

Examples of suitable solvents are linear or cyclic glycol ethers, in particular diethylene or dipropylene glycol, diols, in particular ethylene glycol or 1,2-propanediol, triols, in particular glycerol, or in general alkyl alcohols, in particular alkyl alcohols having 1 to 5 C atoms. Preferred solvents are alkyl alcohols having 1 to 5 C atoms, particularly preferably 2 to 4 C atoms and most preferably 2 to 3 C atoms. Examples of suitable alkyl alcohols are methanol, ethanol or propanol. Preferred are ethanol or 2Propanol. Preferably, no methanol is added as a solvent in the process according to the invention. Due to its toxic properties, methanol is frowned upon in many applications. However, this does not mean that the substances (starting materials) used in the abovementioned preferred embodiment of the process according to the invention, for example starting materials containing protective colloids such as polyvinyl alcohols, can not nevertheless contain proportions of methanol. In a particularly preferred embodiment, however, all starting materials, in particular the starting materials, are free of methanol. In the case of alternative A) of the present invention, the solvents during the emulsion polymerization to 0.5 to 10 wt .-%, preferably 0.7 to 8 wt .-%, particularly preferably 0.9 to 7 wt .-% and am most preferably present at 1 to 6 parts by weight, in each case based on the total weight of the monomers, wherein the aforementioned values can be combined in any desired manner.

In the case of the alternative B) of the present invention, the solvents during the emulsion polymerization are preferably from 0.2 to 10% by weight, more preferably from 0.3 to 5% by weight, still more preferably from 0.3 to 4.2% by weight .%, even more preferably from 0.4 to 4.1, most preferably from 0.6 to 4.1% by weight, and most preferably from 0.8 to 4.0% by weight, based in each case on the total weight of the monomers, which values can be combined in any desired manner.

For both alternatives, the abovementioned amounts of solvents also comprise the proportions of solvent which are introduced into the process according to the invention as an impurity or as an accompanying material of the educts, for example the starting materials, such as any alkyl alcohol impurities of polyvinyl alcohol.

In the case of alternative B) of the present invention, the use of one or more anionic sulfosuccinic esters of the general formula (I) is a further essential aspect.

M is preferably a cation of hydrogen or alkaline earth metals or an ammonium ion, more preferably a cation of the alkaline earth metals or an ammonium ion, and most preferably a cation of sodium or potassium or ammonium.

Preferred linear or branched alkyl radicals R ^{1 of} the general formula (I) contain at least 4 C atoms, more preferably at least 6 C atoms, even more preferably at least 7 C atoms, more preferably at least 8 C atoms, even more preferably at least 9 C atoms, and most preferably at least 10 C atoms to preferably at most 14 C atoms, and more preferably at most 13 C atoms. In the aforementioned embodiments of R ^l , the aforementioned

Values concerning the number of C atoms of the linear or branched alkyl groups occur in any combination. Preferred alkylene oxide groups - {R ² -O) _n -X contain as R ² preferably a linear or branched alkylene unit having 2 to 3 C atoms and particularly preferably an alkylene unit having 2 C atoms. In the preferred alkylene oxide groups - (R ² -O) _n -X, n is preferably an integer from 2 to 20, more preferably from 2 to 10, and most preferably from 3 to 6. Preferred Alkylene Oxide Groups - (R ² -O) _n -X preferably contain as X, more preferably, even more preferably and most preferably the same linear or branched alkyl radicals which are correspondingly listed for R ^{1 of} the general formula (I).

Preference is given to diesters of the anionic sulfosuccinic esters of the general formula (I); ie, preferably all R ^{1 of} the general formula (I) are linear or branched alkyl radicals having 4 to 17 C atoms or for alkylene oxide groups - (R ² -O) _n -X; ie preferably no R ^{1 of} the general formula (I) is a cation M.

Examples of suitable anionic sulfosuccinic acid esters of the general formula (I) are dioctylsulfusuccinate sodium salts or diethylhexylsulfosuccinate sodium salts, also known under the trade names Aerosol® OT or Empimin® OT; or didecylsulfosuccinate sodium salts, also known under the trade names Geropon® DDS65 or Empimin® ID65; or di-isotridecylsulfosuccinate sodium salts, also known under the trade names Geropon® Bis / Sodico or Empim® TR70 or Aerosol® TR70; or monoesters of the sulfosuccinic acid esters of the general formula (I) in which R ^{1 is} - (R ² -O) _n -X and R ^{2 is} an alkylene unit having 2 C atoms, X is a linear or branched alkyl radical having 10 to 12 C atoms and n is an integer from 3 to 6 and M can assume the meanings given above, as sodium salts also known under the trade names Geropon® ACR4 or Aerosol® A102 or Empicol® PCA507 or Epicol® SDD; or diesters of the sulfosuccinic acid esters of the general formula (I) in which R ^{1 is} - (R-O) _n -X and R ^{2 is} an alkylene unit having 2 C atoms, X is a linear or branched alkyl radical having 6 to 14 C atoms and n is an integer from 2 to 10 and M can assume the meanings given above. The anionic sulfosuccinic acid esters of the general formula (I) can be used as pure substance, as a mixture with vinyl acetate and / or further comonomers, as a mixture with water, or as a mixture with one or more solvents and optionally water in the process according to the invention.

It is also possible to use mixtures of several anionic sulfosuccinic acid esters of the general formula (I). It is also possible to use one or more anionic sulfosuccinic acid esters of the general formula (I) in admixture with one or more nonionic emulsifiers and / or one or more other anionic emulsifiers.

Examples of suitable nonionic emulsifiers which can be used in admixture with the anionic sulfosuccinic acid esters of the general formula (I) are nonionic, branched or linear alkyl ethoxylated emulsifiers, polyalkylene oxides or block copolymers of alkylene oxides. Preferred are ethoxylated fatty alcohols, including oxoalcohols, with branched or straight-chain alkyl radical, where the alkyl radical has 4 to 40 C atoms, preferably 8 to 18 C atoms and is ethoxylated with 2 to 60, preferably 4 to 40 ethylene oxide units. Examples of these are C12 to C14 fatty alcohols having 3 to 40 ethylene oxide units, C13 to C15 fatty alcohols (oxo alcohols) having 3 to 40 ethylene oxide units, C16 to C18 fatty alcohols having 11 to 60 ethylene oxide units , C10 ~ or C13-fatty alcohols (oxo alcohols) with 3 to 40 ethylene oxide units, polyoxyethylene sorbitan monooleate with 20 ethylene oxide units. Particularly preferred ethoxylated fatty alcohols are the polyethylene oxide ethers with 2 to 60 ethylene oxide units of linear alcohols (such as oleyl alcohol, stearyl alcohol) or Iso tridecylalkohol. Copolymers of ethylene oxide (EO) and propylene oxide (PO) with an ethylene oxide content of 10 to 40% by weight and a molecular weight of 1500 to 3000 are also preferred as nonionic, ethoxylated emulsifiers. Particularly preferred are EO-PO copolymers with an EO content of 10 to 30 wt .-%. Advantageously, mixtures of said emulsifiers can be used. Examples of suitable anionic emulsifiers which can be used in admixture with the anionic sulfosuccinic acid esters of the general formula (I) are linear or branched alkyl sulfates having 2 to 20, preferably 6 to 16, especially 8 to 14 C atoms or ethoxylated anionic emulsifiers , in particular linear or branched alkyl ether sulfates having 4 to 40 carbon atoms and 2 to 40 ethylene oxide units.

In preferred embodiments, one or more of the anionic sulfosuccinic acid esters of general formula (I) are used in admixture with one or more linear or branched alkyl nonionic ethoxylated emulsifiers or in admixture with one or more nonionic ethylene oxide-propylene oxide copolymers.

The anionic sulfosuccinic acid esters of general formula (I) are in alternative B) generally in an amount of from 0.5 to 4 wt .-%, preferably 0.8 to 3.5 wt .-%, particularly preferably 1.0 to 3.0 wt .-%, and most preferably 1.2 to 2.7 wt .-%, each based on the total weight of the monomers, during the emulsion polymerization.

The proportion of anionic emulsifiers, preferably of the anionic sulfosuccinic acid esters of general formula (I), in alternative B) is generally at least 10% by weight, preferably at least 30% by weight, more preferably at least 50% by weight. even more preferably at least 51% by weight, more preferably at least 55% by weight, very preferably at least 60, even more preferably at least 80% by weight, very preferably at least 90% by weight and in particular from 90 to 99 wt .-%, each based on the total weight of the total emulsifiers used in emulsion polymerization. In emulsion B, the most preferred alternative emulsifiers used in the emulsion polymerization are exclusively the anionic sulfosuccinic acid esters of the general formula (I).

In alternative B), the anionic sulfosuccinic acid esters of the general formula (I) are generally present in an amount of from 11.1 to 80.0% by weight, preferably 18.6 to 66.7% by weight, more preferably 25.5 to 55.6% by weight and most preferably 37.5 to 53.5% by weight, in each case based on the total weight of the protective colloids and anionic sulfosuccinic acid esters of the general formula (I), during the emulsion polymerization.

The anionic sulfosuccinic acid esters of general formula (I) are in alternative B) generally in an amount of 10.0 to 79.4 wt .-%, preferably 16.6 to 61.2 wt .-%, particularly preferably 20.5 to 54.2% by weight, and most preferably 24.0 to 51.4% by weight, based in each case on the total weight of the emulsifiers and protective colloids, during the emulsion polymerization.

The emulsifiers in alternative B) are generally present in an amount of 11.2 to 88.7% by weight, preferably 18.8 to 75.8% by weight, particularly preferably 25.7 to 70.2% by weight. and most preferably from 27.6 to 68.6% by weight, based in each case on the total weight of the emulsifiers and protective colloids, during the emulsion polymerization. Also in alternative A), one or more nonionic or ionic emulsifiers can be used alone or in admixture. For this purpose, for example, the aforementioned nonionic or ionic emulsifiers are suitable. Ionic emulsifiers are preferably anionic emulsifiers. Examples of suitable anionic emulsifiers are listed above in the description of the emulsifiers for alternative B). For alternative A), sulfosuccinic acid esters of the general formula (I) are generally excluded from emulsifiers, in particular ionic emulsifiers. In the case of alternative A), any emulsifiers used may be used in an amount of 0.1 to 4% by weight, preferably 0.5 to 3.5% by weight and more preferably 1.0 to 3.0% by weight. , based in each case on the total weight of the monomers, during the emulsion polymerization. In preferred embodiments of alternative A) no emulsifiers are used. In alternative A) as in alternative B), preferably no alkylphenol ethoxylates are used as emulsifiers. Alkylphenolethoxylates are umweit- and health. The solvents may be in the form of mixtures with the monomers,

Protective colloids and / or optionally emulsifiers, in particular the anionic sulfosuccinic esters of the general formula (I) are introduced. Thus, mixtures of one or more solvents with one or more protective colloids or premixes containing one or more protective colloids and one or more solvents can be fed to the process according to the invention. Likewise, one or more solvents can be mixed with one or more anionic sulfosuccinic acid esters of the general formula (I) or with premixes comprising one or more anionic sulfosuccinic acid esters of the general formula (I) and one or more solvents and in the form of the mixtures thus obtained be fed to the invention. These mixtures can be used in the process of the invention as a template or dosage. For the preparation of the mixtures, the emulsifiers and / or protective colloids or the abovementioned premixes or starting materials are preferably 0.0 to 3.8% by weight, more preferably 0.5 to 3.8% by weight and most preferably 0, 5 to 3.0 parts by weight of solvent, based on the total weight of the monomers, mixed.

The solvents can be introduced completely or partially before the initiation of the emulsion polymerization in the reactor or can be added in total or partly during the emulsion polymerization. The solvents can be added, for example, to substantial portions during the emulsion polymerization. When using emulsifiers, the solvents are preferably distributed in the same ratio as the emulsifiers on initial and dosage. In this case, a greater proportion of the solvent is preferably simultaneously, but optionally spatially separated, with a portion of the anionic sulfosuccinic ester of the general formula (I) added after initiation of the emulsion polymerization as initially charged. Vinyl acetate is preferably added to from 10 to 70% by weight, more preferably from 10 to 50% by weight, most preferably from 15 to 50% by weight, and most preferably from 22 to 42% by weight, before initiation of the emulsion polymerization. submitted in the reactor, in each case based on the total weight of the total vinyl acetate used.

Before initiation of the emulsion polymerization, preferably 40 to 100% by weight, more preferably 50 to 100% by weight and most preferably 50 to 75% by weight of ethylene are introduced into the reactor, in each case based on the total weight of the total ethylene used ,

If, in addition to vinyl acetate and ethylene, further comonomers or auxiliary monomers are used, they can be initially introduced into the reactor before the initiation or added in total during the reaction. The other comonomers or auxiliary monomers can also be partially charged and partially metered.

The protective colloids are preferably initially charged to at least 20% by weight, more preferably at least 50% by weight and most preferably to 100% by weight, prior to initiation of the emulsion polymerization, based in each case on the total weight of the total protective colloids used. Alternatively, the protective colloids can be metered to 100%, based on the total weight of the total protective colloids used.

When emulsifiers are used, they are preferably at least 25% by weight, more preferably at least 40% by weight, most preferably from 55 to 85% by weight and most preferably from 62 to 82% by weight before initiation submitted to the emulsion, in each case based on the total weight of the total used

Emulsifiers. Alternatively, the emulsifiers can be metered to 100%, based on the total weight of the total emulsifiers used. The solvents are preferably at least 20% by weight, more preferably at least 30% by weight, more preferably at least 40% by weight, and even more preferably at least 50% by weight, most preferably at least 65% by weight. -% and in particular to 80 to 100 % By weight, based in each case on the total weight of the total solvents used, prior to the initiation of the emulsion polymerization. The hereby optionally remaining proportion of solvent is added. Alternatively, the solvents may be at least 50% by weight, preferably at least 65% by weight, more preferably at least 85% and most preferably 90 to 100% by weight, based in each case on the total weight of the total used solvents are added after initiation of the emulsion polymerization. The hereby optionally remaining proportion of solvent is presented.

In particular, solvents, especially alkyl alcohols, at least 50 wt .-%, preferably at least 65 wt .-%, more preferably at least 85 wt .-% and most preferably at 90 to 100 wt .-%, each based on the Total weight of the total solvents used, submitted before initiation of the emulsion polymerization, provided that they are used in a proportion of 0.5 to 4 wt .-%, based on the total monomers used. In particular, also solvents, especially alkyl alcohols, at least 50 wt .-%, preferably at least 65 wt .-%, more preferably at least 85 wt .-% and most preferably from 90 to 100 wt .-%, each based on the total weight of the total solvents used, dosed after initiation of the emulsion polymerization during the course of the emulsion polymerization, provided that they are used in a proportion of greater than 4.5 wt .-%, based on the total monomers used.

Surprisingly, the cohesion and / or the adhesion properties of the vinyl acetate-ethylene copolymers obtainable in this way can be selectively increased or controlled not only with the amount but also with the distribution of the solvents on initial and metered additions. The initiator is preferably added in total. When using a redox initiator combination, one of the two components is preferably at least partially introduced, particularly preferably, the reducing agent component is at least partially presented. The emulsion polymerization according to the invention is generally divided into the following phases or process steps as a whole:

(i) preparing the reactor feed, <ii) initiating the polymerization, (d) metering phase, <iv) outgassing, (v) postpolymerization and, optionally, but preferably (vi) steam stripping and (vii) final adjustment. After, during or before the postpolymerization, the polymerization batch is released from the reactor into a downstream vessel, if appropriate with addition of defoaming agents. Cooling of the approach takes place during or after the

Post-polymerization or after steam stripping. Final adjustment of solids content and / or viscosity, addition of biocides, is usually carried out at least at 40 ° C cooled approach. When carrying out the emulsion polymerization, the procedure is generally such that the stated constituents of the reaction mixture, in particular monomers, protective colloid, solvent and / or optionally emulsifier, are initially charged in the stated proportions, and the initial charge is then heated to polymerization temperature. Advantageously, the reactor template is present on a larger scale

Start the initiation heated to a temperature which is between 10 ° C and 40 ° C below the desired polymerization temperature, and the exothermic heat of reaction used to heat the reactor to reaction temperature. After reaching the polymerization temperature, the initiator or in the case of a redox initiator combination becomes

Oxidizing agent and reducing agent added and thus initiated reaction start, and started with the uniform addition of the residual amounts of monomer, optionally emulsifier and optionally protective colloid after exothermic onset of polymerization. It is also possible in the dosing phase to add the different doses with continuously or stepwise increasing or decreasing rates in each case independently of one another to the polymerization mixture of the template during the course of the reaction. It is also possible to add one or more dosages each at a constant rate and remaining dosages with continuously or gradually increasing or decreasing rates. The process preferably proceeds with increasing rates for the monomer doses, in particular especially for the vinyl acetate dosage, and for the initiator dosage (s).

The pH during the polymerization reaction is about 2 to 7, preferably about 3 to 6, and more preferably about 3.5 to

5.5. For this purpose, it may be necessary to adjust the pH of the reactor master before starting the initiation to pH values of less than 6, preferably less than 5 and particularly preferably in the range between 3 and 4.5. Suitable pH-adjusting agents are known inorganic or organic acids, of which phosphoric acid and formic acid are particularly preferred. It is also possible to add customary buffer substances to the reactor master before the initiation or to meter it in during the reaction, preferably it is possible to dispense with such buffer substances.

Volatile organic compounds (VOC, volatile organic compounds), such as residual monomers or solvents, can, if desired, be distilled off from the aqueous dispersions of the vinyl acetate-ethylene copolymers, in particular using entrainers (stripping), such as nitrogen or preferably water vapor. The latter is also known under the term steam stripping. The distilling or stripping is preferably carried out at temperatures of 50 to 100 ° C, preferably in vacuo. The stripping can also be repeated several times. Volatile organic substances have a boiling point of less than 250 ° C at atmospheric pressure.

Optionally, the aqueous dispersions of the vinyl acetate-ethylene copolymers have a content of volatile organic substances of preferably <2000 ppm and particularly preferably <1000 ppm, based on the weight of the aqueous dispersions; In particular, the proportion of alkyl alcohols is preferably ≦ 500 ppm, more preferably ≦ 100 ppm and most preferably from -i 75 ppm, based on the weight of the aqueous dispersions of the vinyl acetate-ethylene copolymers.

In a preferred embodiment, the procedure is such that 22 to 32 wt .-% of ethylene, based on the total monomer vinyl acetate and ethylene; 1.5 to 3.5 wt .-%, based on the total weight of all Mo monomers, to protective colloids, in particular to partially saponified standard polyvinyl alcohols having a mass-average degree of polymerization of from 600 to 2000 and an average degree of hydrolysis of from 86 to 96 mol%, or to fully saponified standard polyvinyl alcohols having a mass-average degree of polymerization of from 600 to 3500 and a mean Degree of hydrolysis of from 96.1 to 99.9 mol%, or of modified polyvinyl alcohols, in particular of ethylene-modified polyvinyl alcohols, having a mass-average degree of polymerization of from 500 to 4500 and an average degree of hydrolysis of from 94.5 to 99.9, or hydroxyethyl cellulose with viscosities, in 2% by weight aqueous solution of -1500 mPas; or mixtures of said protective colloids, and 0.8 to 6 wt .-%, based on the total weight of all monomers, solvents and optionally 1 to 3.5 wt .-%, based on the total weight of all monomers, of one or more anionic Sul - Fibernsteinsäureestern the general formula (I) can be used; and 15 to 50% by weight of the vinyl acetate, based on the total weight of the total vinyl acetate used; From 50 to 75% by weight of the ethylene, based on the total weight of the total ethylenol used; 100% by weight of one or more protective colloids, based on the total weight of the total protective colloids used; 0 to 50

% By weight of one or more solvents, based on the total weight of the solvents, a part of the reducing agent component and optionally 50 to 85 wt .-% of one or more emulsifiers, based on the total weight of the total emulsifiers used, be submitted before initiation in the reactor ; The reactor template is adjusted to a pH between 3 and 5 and heated to a starting temperature of 10 ° C to 60 ° C. The reaction can then be initiated by parallel dosing of oxidizing agent hydrogen peroxide and reducing agent Na formaldehyde sulfoxylate, Brüggolit®, or Brüggolit® FF6, and briefly after exothermic reaction start with uniform parallel metering of vinyl acetate, ethylene, water, solvents, optionally emulsifiers and continuing redox initiator dosages. The dosages of ethylene, solvents and, if appropriate, emulsifiers may end with the vinyl acetate dosage, preferably the dosages of ethylene, solvents and optionally emulsifiers are terminated before the end of the vinyl acetate dosage. In particular, it is advantageous to adjust the dosages of solvent and given if emulsifiers already at a level of 50 to 75 wt .-% of the metered vinyl acetate content to end. At the end of the vinyl acetate metering, optionally at elevated rates, the redox initiator doses continue in the polymerization phase until the exothermic reaction subsides and / or the unreacted vinyl acetate content decreases to less than 2% by weight, preferably less as 1 wt .-%, based on the total amount, of aqueous dispersion has decreased. Subsequently, in the reactor, during the transfer of the reactor contents into a downstream vessel, or in this downstream vessel, the proportion of unreacted monomer to at least less than 0.1 wt .-%, based on aqueous dispersion, by post-polymerization, with the addition of further redox initiator components, and / or by common steam stripping, reduced.

The aqueous dispersions of vinyl acetate-ethylene copolymers obtainable in this way have a solids content of generally> 56%, preferably> 58%. The viscosity of the aqueous dispersions is generally between 1,000 and 20,000 mPas, preferably between 2,000 and 10,000 mPas, determined as Brookfield viscosity Bf20, at solids contents of 60% and 23 ° C.

The emulsion polymerization may also be carried out in the presence of a preformed polymer dispersion, often referred to as a seed latex or seed. For example, it is possible to use a produced by the process according to the invention vinyl acetate-ethylene copolymer as a seed and to submit the seed partially or completely or to dose partially or completely. Advantageously, however, in order to achieve the advantageous effects achieved according to the invention, no use of a seed is necessary. Due to this, the effort generated by the use of a seed can be dispensed with in the procedure according to the invention.

During the emulsion polymerization, the common chain regulators can be used. Preferably, however, the use of chain regulators is dispensed with. In particular, in addition to the listed monomers, protective colloids, optionally emulsifiers and solvents, no regulatory substances with transfer constants for viscous nylacetate C _s > 100 * 10 ^"4 ; transfer constants for the polymerization of vinyl acetate to various substances are listed, for example, in" Vinyl Polymerization ", Part I, Ed. GE Ham, Marcel Dekker, New York 1967, Chapter 4. Particularly preferred is polymerized in the absence of aldehyde or mercapto regulators. The use of chain regulators leads to copolymers which surprisingly have a lower cohesion when used as adhesives. The average molecular weight of the vinyl acetate-ethylene copolymers was, as is customary and widespread in industrial practice, by the K value according to Fikentscher (H. Fikentscher, Cellulochemistry 13 (1932) 58; see also W. Philippoff : Viscosity of colloids, published by Theodor Steinkopff, 1942, p. 172), obtained from viscosity measurements in accordance with DIN 51562. The K value of the vinyl acetate-ethylene copolymers is generally 65 ≦ K value ≦ 130, preferably 75 to 125, more preferably 85 to 125 and in particular 90 to 120. The K value according to Fikentscher correlates with the limiting viscosity number [η] Staudinger (see eg PJ Flory, Principles of Polymer Chemistry, Cornell University Press, 1953, p. 308 ff); Accordingly, this amounts to 0.88 ≦ [η] ≦ 3.18 dl / g, preferably 1.14 dl / g ≦ [η] ≦ 2.96 dl / g, more preferably 1.44 dl / g ≦ [η ] - 2.96 dl / g and in particular 1.60 dl / g ≤ [η] <■ 2.74 dl / g.

Surprisingly, it has been found that the solvents used according to the invention, in particular the alkyl alcohols, have a comparatively small influence on the K value and, as a rule, do not lower it below K values of 90.

Surprisingly, by the process according to the invention, vinyl acetate-ethylene copolymers were obtained which, as or when used in adhesives, lead to an increase in the adhesion even on critical substrates, for example polymer substrates such as polystyrene or polyethylene terephthalate films, in comparison to conventional vinyl acetate-ethylene copolymers and at the same time the cohesion of the adhesive film satisfies the specified minimum requirement of preferably at least 0.2 N / mm ² , in particular at least 0.5 N / mm ² , and In some cases significantly higher cohesion values can be achieved and thus cause a property level with high cohesion and high adhesion. It was particularly surprising that in the presence of solvents, especially of alkyl alcohols, even in the absence of emulsifiers, the adhesion in the adhesive composite is significantly increased, without at the same time the cohesion of the adhesive film decreases in the same way as for the use of emulsifiers from DE-A 102009001097 is known. The use of the solvents, in particular the alkyl alcohols, and their amount used during the emulsion polymerization had a decisive influence on these effects. By a subsequent addition of solvent, especially of alkyl alcohol, after completion of the emulsion polymerization, these effects according to the invention are not achieved, or if at all, to a much lesser extent. Likewise, the effects according to the invention are not achieved, or if at all, to a much lesser extent by subsequent addition of the anionic sulfosuccinic acid esters.

The use according to the invention of solvents, in particular of alkyl alcohols, and optionally by the use according to the invention of anionic sulfosuccinic acid esters of the general equation (I) in emulsion polymerization processes has in particular also achieved that with the vinyl acetate-ethylene copolymers obtainable according to the invention as or in Adhesiven a variety of different polymer substrates, especially critical polymer substrates such as polystyrene or polyester, can be bonded in the desired manner with a property level with high cohesion and high adhesion.

Likewise, the proportion of ethylene or vinyl acetate according to the invention in the vinyl acetate-ethylene copolymers has a significant influence on adhesion and cohesion as well as the property level with high cohesion and high adhesion. When using vinyl acetate-ethylene Mischpoly erisaten with lower ethylene content, for example, at an ethylene content of <18 wt .-%, these properties fall dramatically compared to the results obtained according to the invention. When used on solvents, such as alkyl alcohol, above 20% by weight, based on the total weight of the monomers, no further positive effects of the adhesion increase are achieved and those higher Amounts are then disadvantageous with respect to any desired nightly removal from the vinyl acetate-ethylene copolymers. The advantageous adhesion and adhesion effects or the property level with high cohesion and high adhesion can be further increased by the distribution of vinyl acetate, ethylene, optionally emulsifier, solvent, especially alkyl alcohol, and protective colloid on initial charge and dosage. In particular, it was surprising that when the solvents, especially the alkyl alcohols on the initial charge and the metered dose, were mixed with the same proportion of solvent, the effect of improving the adhesion could in some cases be increased while the cohesion was maintained at a high level.

The vinyl acetate-ethylene copolymers according to the invention are suitable for use as or in adhesives for the bonding of any substrates, preferably cellulosic materials, such as paper, cardboard, wood, or plastics, such as polyethylene, polyvinyl chloride, polyamide, polyester, polystyrene or acrylonitrile Butadiene styrene. The substrates may be, for example, fibers, films or molded parts. Corresponding Anwendungsfeider the adhesives are in particular packaging materials or woven or non-woven fiber materials.

Particularly suitable are the vinyl acetate-ethylene copolymers as or in adhesives for the bonding of cellulosic substrates, in particular paper, cardboard or cotton fabric, with plastics such as polyethylene, polyvinyl chloride, polyamide, polyester, polystyrene or acrylonitrile-butadiene-styrene, in particular in the form of Kunstofffolien, or for the bonding of two plastics together, for example, for film / foil bonding.

However, the vinyl acetate-ethylene copolymers are also suitable for other customary applications of such polymers, for example as binders and / or coating agents, in particular for fibrous substances or structures, for example in the area of wovens or preferably nonwovens, as for nonwovens or fabrics. The vinyl acetate-ethylene copolymers according to the invention, optionally with the addition of further amounts of protective colloids and customary additives, are also suitable for the preparation of water-redispersible polymer powders, in particular by spray drying, and as such, for example, as additives. used in the construction industry for cementitious and non-cementitious applications to improve adhesive properties. It is possible to use the customary processes and apparatus in order to obtain the products of the emulsion polymerization according to the invention by means of

Drying in water redispersible polymer powder to convict.

It was particularly surprising that the property level with high cohesion and high adhesion even for the bonding of particularly critical substrate combinations was achieved by the inventive approach, as for bonding of plastics, especially polystyrene or polyester films, such as polyethylene terephthalate, with each other or with cellulosic materials, such as paper, cardboard, or cotton fabric.

Thus, adhesive films of the vinyl acetate-ethylene copolymers according to the invention preferably show cohesion values, measured as heat resistance, of at least 0.2 N / mm ^s , preferably of 0.5 N / mm ^2, and preferably simultaneously the following high adhesion values, even for difficult to bond substrates:

Polystyrene film Sidaplay® Polyflex 90 film adhesively bonded to vinyl acetate-ethylene copolymers according to the invention preferably exhibits a peel strength of at least 3.8 N / cm, preferably at least 4 N / cm, and with vinyl acetate according to the invention at a withdrawal speed of 5 mm / min. Ethylene copolymers to cotton bonded Polyethelenterephthalat film Hostaphan® RN125 preferably shows a peel strength of at least 3.4 N / cm, preferably at least 4 N / cm or at a take-off speed of 900 mm / min at a take-off speed of 10 mm / min a peel strength of at least 1.2 N / cm, preferably at least 1.5 N / cm. At the same time, with the vinyl acetate-ethylene copolymers according to the invention having a property level with high adhesion and high adhesion, a liability sum, HS, of preferably at most 18 seconds or less is achieved. In addition, the aqueous dispersions of the vinyl acetate-ethylene copolymers according to the invention have a high setting speed of the adhesive film which, measured as the starting speed (AZG), reaches values of preferably 3 seconds or less. The individual methods, conditions, and materials for determining the cohesive, adhesive, or tensile speed parameters are described in detail below under the heading "Adhesive Properties Testing Methods."

The following examples serve to illustrate the invention without restricting these to the cited examples.

First, the test methods for characteristic dispersion characteristics and the test methods for the determination of adhesive properties are described:

Test methods for characteristic dispersion characteristics:

Solid content / Dry residue (FG-Ex):

For the experimental determination of the solids content, in percent based on dispersion, 0.3 g of polymer dispersion were weighed and dried as a thin film for 30 minutes at 150 ° C in a convection oven. The drying residue was, after cooling in a desiccator on silica gel, weighed back and the solids content in wt .-%, based on dispersion, calculated from residue and weight. Results for experimental solids FG-Ex are given in Table 3.

Viscosity (Bf20-Ex):

The viscosity of the dispersion was measured after tempering to 23 ° C with a Brookfield viscometer, using the optimum for the respective viscosity level spindle at 20 rpm. The viscosity is given in mPas. For better comparability, the viscosity values measured for the experimental solids content, FG-EX, were values, BF20-EX, to a solids content of 60%: with satisfactory approximation, the following applies to the polymer dispersions investigated here:

Bf20 (60%) = (Bf20-EX) * EXP (0.5 * (60 - (FG-EX))).

Results obtained are shown in Table 3.

Particle sizes (X _{3, 50} ):

To determine a particle size distribution using the Beckmann Coulter® LS 13 320 measuring device according to the device specification, using the optical constants for polyvinyl acetate, the dispersion was diluted with water. The particle size here is the central value of the volume distribution function of the particle diameter x ₃ , ₅ o in nanometers. The determined particle size distributions have essentially monomodal distribution densities whose mode value is close to the central value of the distribution. Results obtained are shown in Table 3.

Sieve residue (grit):

The residue of the dispersion in parts per 10 ⁶ , based on dispersion (ppm), characterizes coarse-grained fractions in the

Dispersion larger than 40 μm. To determine such undesirable and minimally-stable portions, 100 grams of the dispersion was diluted with up to one liter of distilled water, then passed through a 150 mesh nylon screen cloth, and the passage filtered through a 40 mesh screen mesh. Each was rinsed with water until the passage was clear. The residue on the sieve fabrics was weighed back after drying and the sieve residue per sieve fabric, based on dispersion, was calculated. In Table 3, the total residue on both sieves was greater than 40] i.

It is expressly mentioned that the indication of residue> 40 pm is a very critical evaluation of the sieve residue. Industrially usual specifications are> 50 μπι or> 60 microns. Experience has shown that in the range between 40 μιη and 60 to about 20% to 50% of the residue between 40 .mu.m and 150 μιη lie. For most applications it is necessary as sufficient that the sieve residue> 40 μπι values of <1000 ppm, preferably of <800 ppm. Results obtained are shown in Table 3. K value and limiting viscosity number:

From the dispersion, a dispersion sample was prepared by weighing into a 50 ml volumetric flask containing 0.5 g of polymer (without polyvinyl alcohol) and 4 g of water. While stirring, tetrahydrofuran (THF) was slowly added dropwise until a clear solution was formed. After tempering to 23 ° C was made up to the calibration mark with THF. The measurement solution had a concentration of 1 g of polymer per 100 ml of solution. Taking into account the Hagenbach correction, the viscosity of a gel-free sample of the measurement solution and the polymer-free comparative solution in the Ubbelohdeviskosimeter (capillary lc) was determined at 23 ° C and thus determined the relative solution viscosity n _Mi. With this the "intrinsic viscosity k" according to Fikentscher, Cellulose Chemistry 13 (1932) 58, and the "K value" at K = 1000 k was calculated. For the inherent viscosity k, the following applies:

where the concentration c _v in g / dl is to be used.

The K value is a common and useful measure correlated with the viscometric average molecular weight of the polymer. The K value is naturally dependent on the copolymer composition and generally decreases with increasing ethylene content of a vinyl acetate-ethylene copolymer.

From the thus determined K value, the concentration dependence of the relative viscosity can be calculated with the given equation. This is followed by calculation of the dependence of the quotient, (η ₈ / c _v ), of specific viscosity, η ₈ = (η _Εβ ι ~ l) f and concentration, c _v , of the concentration. Extrapolation - expedient by exponential function - to infinite dilution yields the intrinsic viscosity [r \]. The concentration is in this case in grams per 100 ml of solution, ie in g / dl, ie [η] results here in dl / g.

The results for K value and intrinsic viscosity [η] are shown in Table 3. Test Methods for Determining Adhesive Properties: Setting Speed {AZG Method):

During the setting of a dispersion suitable as an adhesive, the strength of the bond increases over time. The speed of the setting operation can therefore be described by changing the strength of an adhesive film as a function of time. With the method of tightening speed (AZG) is now determined that time at which a bond area of 1 cm ² an acceleration-free vertical tensile force of 2 Newton withstand. For the bonding, a standard index card cardboard from Koehler Feinpapiere was coated with a 50 μm dispersion film and bonded to a 1 cm ² circular piece of the same cardboard. After different times, the resistance of the bond to the vertical tensile force of 2 N was tested and thus the time in seconds during which the connection remains. The result is given as AZG in seconds. Falling AZG values of different dispersions thus characterize increasing setting rates. For a sufficiently fast setting, it is required that the setting rate should be ≤ 3 seconds according to the AZG method. Results obtained are shown in Table 3.

Cohesion:

From 6 plywood sticks (135 x 30 x 4 mm) 6 test pieces with a glued area of 9 cm ² each were produced. For this purpose, two rods each with a dispersion layer of 100 pm were applied to a length of 30 mm and connected without pressure for 1 minute. Subsequently, the bond was applied for 30 minutes with a pressure of 0.2 N / mm ² . The specimens were then stored at 23 ° C and 50% humidity for 7 days and tempered before the test for 4 hours at 70 ° C in a convection oven. Thereafter, the strength of the bond was determined immediately in the warm state with a tensile tester at a take-off speed of 50 mm / min until the bond broke. The maximum force at break, based on the bond area, is given as bond strength (cohesion) in N / mm ² . As a result of the cohesion, the mean value of the tests of all 6 test specimens is rounded to one Decimal place specified. Cohesion values of at least 0.2 N / mm ⁸ , preferably of at least 0.3 N / mm ² and in particular of at least 0.5 N / mm ^{2 are} required. Results of the cohesion test are given in Table 4.

Liability sum:

Paper strips of soda kraft paper, bleached on one side, white, 60 g / m ² , 10 x 50 mm, were coated with 50 μm layer thickness of the dispersion to be tested on the rough paper backside and bonded to 7 different plastic films (film 1: polyvinyldichloride Film of the company PKL Flexible packaging, PVDCl-coated side is glued, film 2: rigid PVC transparent film 250 of the company Pütz GmbH & films KG, film 3: soft PVC film H068 / 200 by the company Pütz GmbH & Folien KG; film 4: soft PVC-Alkor blue film 40 from Alkor GmbH; film 5: cast polyamide film PA 6/100 μm from Petopa Verpackunsfolien Handels GmbH; film 6: polyester film Hostaphan ® RN36 from Pütz GmbH & Folien KG; film 7: cellulose di-acetate N50 / 50 μm film from Pütz GmbH & Folien KG). After 2 hours drying time, the test strips were peeled off by hand and the adhesion (adhesion) was evaluated as follows:

1: very good adhesion, 100% paper tear

2: good adhesion, mostly paper tear

3: adhesion, separation with resistance

4: no liability, chipping off

By adding the 7 evaluation values, the liability sum was obtained, which can vary between 7 (very good adhesion on all 7 substrates) and 28 (no adhesion on all substrates). The liability sum should be ≤ 18, preferably ≤ 17. Results for the liability sum HS are given in Table 4.

Adhesion (peel strength):

For a quantitative determination of the adhesion, a Sidaplax® Polyflex 90 film was used as the polystyrene substrate PS and a Hostaphan® N125 film as the polyethylene terephthalate substrate.

An adhesive bond with a standard cotton fabric according to DIN53939 with the WFK code 10A was produced.

For this purpose, both the cotton fabric and the film were coated with the aqueous dispersion by means of a 100 μm wire doctor blade. The two coated substrates were then manually laminated and pressed using a rubber-coated metal roller (3.5 kg). After bonding, the specimens were each dried for 24 hours under standard conditions (23 ° C. and 50% relative atmospheric humidity).

For the production of the adhesive bond between polystyrene and cotton already cut 2.5 cm wide strips of cotton fabric with 4.8 cm wide strips of Sidaplax® Polyflex 90 film were glued in the middle on a length of 15 cm (5 cm remain unpainted).

For the production of the adhesive bond between polyethylene terephthalate and cotton, A4-sized areas of the cotton fabric were bonded with Hostaphan® RN125 film (5 cm remained unglued on one transverse side), from which strips 2.5 cm wide were then dried after drying Cutting machine were cut as specimens.

To test the adhesion (peel strength), the cotton fabric was delaminated from the film in a tensile tester. For this purpose, the non-bonded sections of the strips were clamped and the cotton fabric peeled off at a withdrawal angle of about 180 degrees from the polymer film. The peel tests were carried out the day after drying of the adhesive bond.

To determine the adhesion to polystyrene (Adh PS) a pull-off speed of 5 mm / min was chosen. With a measuring path of 60 mm, the delamination force (tear resistance) between 20 and 60 mm was measured and averaged.

To determine the adhesion to polyethylene terephthalate, two different measuring speeds were selected: a low take-off speed of 10 mm / min (slow peeling, Adh PET1) and a high take-off speed of 900 mm / min (rapid peeling, Adh PET2). For the low take-off speed, a 60 mm measuring path was set, whereby the tear propagation resistance between 20 and 60 mm was measured and averaged. At the higher measuring speed of 900 mm / min, a measuring path of 150 mm was set, whereby the tear propagation resistance between 20 and 150 mm was measured and averaged. The high take-off speed for PET film of 900 mm / min was additionally selected, since at high take-off speed weaknesses with regard to adhesion are particularly clear. For each substrate and take-off speed 8 bonds were delaminated. The adhesion (peel strength) results from the average tear strength for all strips and the strip width of 2.5 cm in each case and is given in N / cm rounded to one decimal place.

It is desired that the following adhesion values are at least achieved:

Adh PS - 3.8 N / cm and Adh PETl = 3.4 N / cm and Adh PET2 = 1.2 N / cm. Preference is given to values of at least:

Adh PS = 4.0 N / cm and Adh PETl = 4.0 N / cm and Adh PET2 = 2.0 N / cm. Particular preference is given to values of at least:

Adh PS = 4.2 N / cm and Adh PETl = 4.1 N / cm and Adh PET2 = 2.5 N / cm. In particular, it may be advantageous to achieve the following adhesion values:

Adh PS = 5.0 N / cm and Adh PETl = 4.1 N / cm and Adh PET2 = 2.5 N / cm.

Results for Adh PS, Adh PETl and Adh PE 2 are given in Table 4.

Examples:

Comparative Examples VI and V2:

For Comparative Examples VI and V2, two commercially available vinyl acetate-ethylene copolymer dispersions were tested which are known for their good adhesion properties. The results are shown in Table 4.

Comparative Example VI:

Mowilith® DM132 is a polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer dispersion of Celanese Corp., which is well known in the art.

Comparison Example V2: Vinnapas® A920 is a stabilized in the presence of polyvinyl alcohol and APEO emulsifier vinyl acetate-ethylene copolymer dispersion of Wacker Chemie AG, which corresponds to the prior art. Examples and Comparative Examples:

The aqueous emulsifier solutions used in the Examples and Comparative Examples are characterized in Table 1 with regard to chemical composition, proportion of solvent, especially of alkyl alcohol, and with respect to concentration of emulsifier active substance.

In Comparative Examples V3, V4, V5, V6, V7A, V7B, V7C, V7D and V7E was polymerized without the use of emulsifiers.

In Comparative Examples V3 to VII was polymerized without separate addition of solvents, especially alkyl alcohols; amounts of alkyl alcohol of <0.04% by weight, based on the total weight of the monomers, which were still present during the polymerization, resulted from corresponding proportions of alkyl alcohol in the polyvinyl alcohol used.

For examples 1 to 26, essentially different proportions of polyvinyl alcohol and different amounts of anionic sulfosuccinic acid esters of general formula I used according to the invention and of inventive solvent, especially alkyl alcohol, were used for the polymerization; Furthermore, the monomers vinyl acetate and ethylene, the sulfosuccinic acid ester used and the alkyl alcohol used were distributed in different proportions to the reactor charge and the dosage. Example 19 alternatively contained a nonionic emulsifier. The following general polymerization instructions were used to prepare the polymer dispersions. Table 2 contains the details of the variations of this process in the individual examples. General Polymerization Procedure for Comparative Examples V3 to VII and Examples 1 to 26: The polymerizations were in each case carried out in a 2 liter pressure reactor which was equipped with a three-stage paddle stirrer, jacket heating, connected to a controllable thermostat, and metering nozzles for the following dosages: Dosing 1 was an aqueous solution of the oxidizing agent of the Redox Initiatorssytems, dosage 2 was the aqueous solution of the reducing agent of the redox initiator system, dosage 3 was the vinyl acetate monomer, dosage 4 was an aqueous solution containing alkyl alcohol and optionally emulsifier (for the comparative examples without alkyl alcohol and without emulsifier only from Water) and dosage 5 was the ethylene monomer.

For the course of the polymerization, the following process steps were followed:

Preparation reactor template:

First, the aqueous preparation was prepared, consisting of

- Original water,

aqueous protective colloid solution which has been prepared separately according to generally known methods,

- alkyl alcohol and emulsifier (as far as introduced into the template),

5% by weight of the reducing agent used in Dosage 2,

The pH of the aqueous receiver was controlled and usually adjusted by addition of phosphoric acid or formic acid to pH 3.5 ± 0.1 (recipe amount 10 g).

Thereafter, 0.4% by weight of a 1% by weight iron ammonium sulfate solution based on the total amount of monomer was added to the receiver, and this aqueous receiver was sucked into the evacuated reactor, followed by 30 g of water for line rinsing.

Subsequently, with stirring, the vinyl acetate of the original was sucked into the reactor, followed by 40 g of water for line rinsing. Subsequently, the reactor was heated to nominal temperature and at the same time the vacuum was broken with ethylene and pressed at nominal stirrer speed, the initial amount of ethylene.

Initiation of the reaction and dosing phase: At temperature and pressure equilibrium, the parallel metering of the two initiator components was started with dosages 1 and 2.

5 minutes after the onset of the reaction, recognizable by increasing the internal temperature or falling of the jacket temperature, the two doses 3 and 4 were started and dosed usually at a constant rate over a period of 120 to 180 minutes. Dosage 4, with a total of 80 g (this may be increased, for example, to 100 g), was stopped at the same time as Dose 3 at the latest.

15 minutes after the start of dosages 3 and 4, the dosage 5 was started, which was terminated about 15 minutes before the end of dosage 3. The required amount of ethylene was pressed in equidistant time intervals with equidistant amounts, usually at intervals of 10 min. Of course, dosage 5 can also be dosed at a constant mass flow rate. To monitor the progress of the reaction, both the temperature and pressure profiles were recorded and sampled from the start of dosing 3 at intervals of 30 to 60 minutes (up to about 10 grams, including flushing volumes) and from their solids content conversion values for vinyl acetate and Ethylene calculated.

Polymerization:

After the end of the dosing 3, the previously, as a rule, constant rates of doses 1 and 2 were gradually increased to 50 ml / h and dosed usually at least 60 minutes; the dosages were terminated sooner, if no reaction was recognizable. The total amounts of dosages 1 and 2 according to the recipe were each 100 g (these amounts can be reduced, for example, to 65 g). In cases in which after the scheduled time still recognizable reaction was present, both doses 1 and 2 were further dosed at a constant rate of 50 ml / h, until no reaction was more recognizable (end of reaction); the Auspolymerisationsphase was completed at the latest 120 minutes after the end of the dosage 3.

Mainly as a result of up to a maximum of 60 minutes longer dosing time and thus higher dosing for doses 1 and 2, the final solids content of the dispersion may be smaller than the formulated solids content; In addition, deviations between the directive quantities and the Actual quantities for pH adjustments lead to deviations between experimental final solids (FG-Ex) and recipe solids (FG-R).

Postpolymerization:

After the end of doses 1 and 2, 10% strength by weight solutions of Na formaldehyde sulfoxylate (Dosage 6) and t-butyl hydroperoxide (Dosage 7) were used for postpolymerization, alternately and in total 4 g each, with a total water rinse of 20 g, metered into the reactor.

Cooling / relaxing / adjusting:

After the end of the postpolymerization, the product was cooled to about 30 ° C and the reactor contents were depressurized. With the addition of 10% strength by weight sodium hydroxide solution (recipe amount 5 g), the pH was adjusted to about 5.5. If solids values of ≤ 62% were determined (with an early end of the reaction), the product was diluted to about 60 to 60.5% solids content while adding water.

More information:

In general, as dosage 1 with a 2% by weight hydrogen peroxide solution and as dosage 2 with a 9% strength by weight Na formaldehyde sulfoxylate solution (Brüggolit®) were used.

The amount of feed water was determined by the concentration of the protective colloid solution used, the recipe solids, and the reactor at the end of the reaction, which - without taking into account the sampling - usually set between 90 and 96 vol .-% was. The total amount of monomer used in the template and doses was 1100 grams for all examples.

As water, also for the preparation of the solutions for dosages 1, 2, 4, 6 and 7, only deionized Wofatitwasser was used.

In the dosage 4 different emulsifiers were used, which are listed in total in Table 1.

Solvents, especially alkyl alcohol (s), in particular ethanol or 2-propanol, were added according to their content in the emulsifier samples according to Table 1 and the emulsifier portion chosen for the polymerization introduced into the template and dosage 4; additional proportions of alkyl alcohol were used as ethanol proportional to the emulsifier content in the initial charge and dosage 4, or, regardless of the emulsifier content, only in dosage 4: For Examples 2, 5, 6, and 7, 5 was only the one corresponding to the respective emulsifier patterns 1 introduced alkyl alcohol present during the polymerization. For Examples 4, 8, 9 and 11, the respective emulsifier patterns were diluted with addition of water and ethanol to 25% by weight emulsifier active substance each time and subdivided to give and dosage 4, so that the values shown in Table 2 for the emulsifier portion (columns 9 and 10) and alkyl alcohol portion (columns 7 and 8) resulted.

For examples 1, 3 and 10 and for the emulsifier-free example le 12, 13, 14, 17, 18, 20 and 21 additional alkyl alcohol was used as ethanol exclusively in the dosage 4. For emulsifier-free Examples 15 and 16, solvent, especially alkyl alcohol, was added completely to the reactor feed prior to the initiation of initiation, and for the emulsifier-free Examples 22 to 26, added solvent, especially alkyl alcohol, was dispensed onto template and feed 4.

For comparative examples V7A to V7E, polymerization was carried out without the addition of emulsifiers and without addition of solvent, the ethylene content of the total monomer being varied between 19 and 32% by weight; Accordingly, the proportion of vinyl acetate monomer decreased, wherein always 50% of the total ethylene and 25% of the total vinyl acetate monomers were initially charged in the reactor.

30 As a protective colloid, a standard low-molecular weight

Polyvinyl alcohol having a mass median degree of polymerization of 850 and an average degree of hydrolysis of 88 mol% used; the content of methanol for this feed was 1 wt .-% based on the weight of feedstock.

35

Table 2 summarizes the recipe data. As illustrated by the data in Table 2, for proportions of polyvinyl alcohol based on total monomer was 2.5; 3.0 and 3.5% by weight of the ethylene Part between 19 wt .-% and 32 wt .-% varied wherein between 40 and 100% of the ethylene and 15% to 50% of the vinyl acetate were initially charged in the reactor. The emulsifier content based on the total monomer was varied between 0% by weight for the emulsifier-free examples and comparative examples and 3.5% by weight, with between 65% and 100% of the emulsifier being initially charged. For Examples 1 to 26 according to the invention, the proportion of anionic emulsifiers according to the invention was between 1.4 and 3.5% by weight and the proportion of alkyl alcohol between 0.2 and 5.0% by weight, based in each case on the total monomer amount, varied. The proportion of solvent used according to the invention, especially alkyl alcohol, in the original varied between 0 and 100% by weight, based on the amount of alkyl alcohol used.

The polymerizations were carried out at temperatures between 50 ° C and 70 ° C reaction temperature, while the reaction mixture was stirred, so that homogeneity of the reaction mixture and heat dissipation was ensured. For this purpose, speeds between 500 and 600 rpm were sufficient in the 2 liter reactor. The setpoint speed was not changed during the reaction. The desired temperature at the beginning of doses 1 and 2 can be lowered to 30 ° C to 40 ° C and the heat of reaction used to further heat the reaction mixture. It was found that the temperature profile of the polymerization in the specified range has no significant influence on the adhesive properties of the products.

As an example, the recipe is given the emulsifier-free comparative example V4:

Reactor template:

204.5 g of water,

137.5 g polyvinyl alcohol solution (20% strength by weight),

6 g Brüggolit (9% strength by weight solution),

10 g phosphoric acid (10% strength by weight solution), standard value for pH adjustment pH 3.5,

4.5 g of iron ammonium sulfate (1% by weight solution),

30 g of water rinse,

240 g of vinyl acetate,

40 g of water rinse, 150 g of ethylene,

Heating to target temperature of 60 ° C; Speed 600 rpm. Dosage 1:

100 g hydrogen peroxide (2% strength by weight, aqueous solution) Dosage 2:

100 g Brüggolit (9% strength by weight, aqueous solution) Dosage 3:

560 g vinyl acetate (metered at a constant rate over 2 hours)

Dosage 4:

100 g of water (metered at a constant rate over 2 hours)

Dosage 5:

150 g ethylene (evenly pressed in intervals in about 90 minutes) Dosage 6:

4 g Brüggolit® (10% by weight, aqueous solution)

10 g of water rinse

Dosage 7:

4 g of t-butyl hydroperoxide (10% by weight, aqueous solution)

10 g of water rinse

Attitude:

5 g sodium hydroxide solution (10% by weight, aqueous solution)

This resulted in prescription at complete monomer conversion 1866 g, corresponding to 1759 ml of polymer dispersion having a recipe solids content of 61.2 wt .-% at a Reaktorendfüllgrad of about 90 vol .-%. For Comparative Examples V3 and V5 to V10 and for Examples 1 to 26 was accordingly, taking into account the information on the polymerization process and the information in Table 2, proceed. Polymer dispersions obtained by the stated polymerization method were analyzed for characteristic dispersion characteristics. Results of these analyzes are given in Table 3.

All the polymer dispersions of Comparative Examples VI to VII and Examples 1 to 26 were also examined for their adhesive properties. The results obtained are summarized in Table 4.

Discussion of the adhesive properties of the dispersions prepared according to the Examples on the basis of the results summarized in Table 4: Comparative Examples VI and V2

The product according to Comparative Example VI gave a good cohesion, but the adhesion values on PET, in particular with rapid peeling, Adh PET2, are clearly too low.

The product of Comparative Example C2 gave very good adhesion values, but the cohesion is much too low and thus far from fulfilling the requirements.

Comparative Examples V3 to V6 (without emulsifier and without inventive amounts of solvent, especially alkyl alcohol):

These emulsifier and in the absence of inventive amounts of alkyl alcohol with different ethylene contents and different distribution of ethylene and vinyl acetate on template and doses produced products resulted in excellent cohesion values, as for vinyl acetate-ethylene copolymers stabilized exclusively in the presence of polyvinyl alcohol , from the

However, the adhesion values for adhesions with PS and PET film with cellulosic substrate do not generally meet the requirements set. Comparative Examples V7A, V7B, V7C, V7D, V7E

For these comparative examples, the ethylene content of the vinyl acetate-ethylene copolymers was varied between 19 and 31% by weight and polymerized in the substantial absence of solvent. The As the ethylene content increases, adhesion to polyester substrate on fast stripping, Adh-PET2, increased from low levels while cohesion assumed nearly constant values, but overall increasing ethylene levels did not generally lead to adhesion enhancement Polystyrene, the adhesion above about 28 wt .-% ethylene again and the data for the Haftungssumme, HS, deteriorated even generally with increasing ethylene levels. At most, the results for the values of ammonia were slightly dependent on the ethylene content and remained at a high level overall. These examples demonstrate that it is not possible to adjust the level of properties with high cohesion and high adhesion merely by changing the ethylene content in vinyl acetate-ethylene copolymers.

Comparative Examples V8 to V10

For these comparative examples, non-inventive anionic emulsifiers and no inventive amounts of alkyl alcohol were used. The resulting polymer dispersions have good cohesion values, but overall the adhesion values do not meet the required property level requirements with high cohesion and high adhesion. Although good adhesion to PS film is achieved with Ex. V9, the adhesion to PET film is much too low. Comparative Example VII and Example 1

The use of anionic onoester according to the invention of sulfosuccinic acid in the absence of inventive amounts of alkyl alcohol in Example VII leads to good cohesion and good adhesion to PET film, but the adhesion to PS film is still too low. This deficit is remedied in Example 1 by the presence of alkyl alcohol according to the invention. Example 1 satisfies all the adhesive properties requirements and achieves high cohesion and high adhesion property levels. Comparison of the adhesive properties of the polymer dispersion of Example 1 with those of Comparative Example V4, which was carried out under the same conditions but in the absence of emulsifier and amounts of alkyl alcohol according to the invention, demonstrates the marked improvement in the adhesive properties Properties by simultaneous use of anionic sulfosuccinate and alkyl alcohol.

Examples 2 to 11

These examples demonstrate the adhesive properties which can be achieved by using emulsifiers according to the invention and inventive simultaneous presence of alkyl alcohol (s), in particular the achievable and adjustable property level with high cohesion and high adhesion. Examples 2 and 3 are based on Comparative Example C5 without emulsifier and alkyl alcohol. Examples 4, 5, 7, 9, 10 and 11 are based on comparative example V4, which is carried out without emulsifier and alkyl alcohol. Example 6 is based on Comparative Example V6 carried out without emulsifier and alkyl alcohol, and Example 8 is based on Comparative Example C3 without emulsifier and alkyl alcohol. For all the examples according to the invention, it is apparent from Table 4 that when the anionic emulsifiers according to the invention are used in the simultaneous presence of amounts of alkyl alcohol (s) according to the invention, the adhesion values go to PS film (column 5) as well as to PET film (column 6) can be increased significantly to at least 4.0 N / cm without at the same time lowering the cohesion (column 3) below the required minimum value of 0.2 N / mm ^a .

It was particularly surprising that the poorly water-soluble and increasingly water-insoluble anionic diester of sulfosuccinic acid with increasing C number in the alkyl radical even at low (Examples 9 and 10) or without additional use of alkyl alcohol (Examples 5, 6, 7) during the polymerization. ie not beyond the proportion which is introduced in each case by the emulsifier patterns according to Table 1 - leads to good cohesion and good adhesion to both PS substrate and polyester substrate and polymer dispersions prepared in this way meet all the requirements. Examples 12 to 18

These examples are based on the comparative example V4 for which neither emulsifiers nor inventive amounts of alkyl alcohol were used. Ex. 12, 13, 14, 17, 18 and 20 have also been incorporated in Absence of emulsifiers but with different amounts of inventive alkyl alcohol, introduced exclusively via the dosage 4 prepared. These examples demonstrate that even with the inventive use of solvent, especially alkyl alcohol, sufficient adhesion values can be achieved even without the presence of emulsifiers, wherein the adhesive properties are even better if for small amounts of solvent, this - as for Examples 15 and 16 takes place - vorderst is introduced into the reactor template.

Example 19

Example 19 is also based on Comparative Example C4. It demonstrates the significant improvement in the adhesion values as a result of the use according to the invention of proportions of solvent, especially alkyl alcohol, in the presence of a nonionic emulsifier.

Examples 20 to 26

The examples were based on comparative example V7D with 28% by weight of ethylene and demonstrate the effect according to the invention of the use of solvent, especially of alkyl alcohol, on the adhesive and cohesive properties of the adhesive bond. Examples 20 to 26 demonstrate the achievement of high adhesion values Adh. PS, Adh-PETl and Adh-PET2 sometimes well above the required minimum values and simultaneously high cohesion values, without falling below the required minimum value, according to the invention using different amounts of solvent, especially alkyl alcohol, in its different distribution on template and dosage. For Examples 20 and 21, solvent, especially alkyl alcohol, was added only to Dose 4, for Examples 22 to 26, alkyl alcohol was dispensed between initial and dosage. These examples show, in particular, which very good adhesion values could be obtained with increasing amounts of solvent, especially alkyl alcohol, in the preferred range for the amounts used, without the cohesion decreasing below a value of 0.5 N / mm ² and thus significantly above that required minimum value of 0.2 N / mm ² .

Legend to Table 1:

Column 2: Label: Code letter of the emulsifier pattern used in Table 2;

Column 3: Alkyl alcohol% indicates the proportion of alkyl alcohol in the emulsifier pattern in% by weight, based on the amount of emulsifier;

Column 4: Conc% indicates the proportion of emulsifier active substance in the emulsifier pattern in% by weight, based on the amount of the emulsifier pattern;

(*) denotes 2-propanol; otherwise ethanol.

Legend to Table 2

Column 1: Example: Example number, V marked comparative example;

Column 2: MS: proportion of protective colloid, based on total monomer, in% by weight;

Column 3: Eth%: proportion of total ethylene, based on the total monomer, in% by weight;

Column 4: Eth-V%; Proportion of ethylene in the template, based on

Total ethylene, in weight percent;

Column 5: VAC-V%: proportion of vinyl acetate in the original, based on total vinyl acetate, in% by weight;

Column 6: Indicator of the E-Gatte pattern according to Table 1;

Column 7: alkyl alcohol%: proportion of alkyl alcohol in wt .-%, based on total monomer;

Column 8: alkyl alcohol% by volume: proportion of alkyl alcohol in the initial charge in% by weight, based on the total amount of alkyl alcohol;

Column 9: ME%: proportion of total emulsifier, based on total monomer, in% by weight;

Column 10 ME-V%: proportion of emulsifier in the original, based on

Total emulsifier, in% by weight;

Column 11 FG-R: solids content by prescription in% by weight, based on

Dispersion.

Legend to Table 3:

Column 1: Example: Example number, V marked comparative example;

Column 2: FG-Ex%: experimental solids content in% by weight based on

dispersion;

Column 3: Bf20-Ex: experimental Brookfield viscosity in mPas;

Column 4: Bf20 (60%): for a solids content of 60% from columns 1 and

2 calculated viscosity in mPas;

Column 5: x3,50: central value of the volume distribution function of the

Particle size in nm;

Column 6: grit: sieve residue greater than 40 μm in ppm;

Column 7: K value;

Column 8: limiting viscosity number, determined from the K value, in dl / g; , d. : stands for "not determined".

Legend to Table 4:

Column 1: Example: Example number, V marked comparative example;

Column 2: AZG: setting rate, measured as AZG in sec; Column 3: Cohes .: Cohesion determined as heat resistance in

N / mm ² ;

Column 4: HS: liability sum;

Column 5: Adh PS: Adhesion / peel strength in N / cm on polystyrene

Sidaplax® Polyflex 90;

Column 6: Adh PETl: adhesion / peel strength in N / cm on polyethylene terephthalate Hostaphan® RN125 at a take-off speed of 10 mm / min (slow peeling: PET1);

Column 7: Adh PET2: adhesion / peel strength in N / cm on polyethylene terephthalate Hostaphan® RN125 at a take-off speed of 900 mm / min (rapid peeling: PET2),

Claims

Patent proceedings: 1. A process for the preparation of vinyl acetate-ethylene copolymers by free-radically initiated emulsion polymerization of vinyl acetate, ethylene and optionally one or more other comonomers in the presence of at least one protective colloid and optionally at least one emulsifier, characterized in that

the vinyl acetate-ethylene copolymers 18 to 45 wt .-% of ethylene units, based on the total weight of the vinyl acetate-ethylene copolymers, and

at least 70 wt .-% of ethylene units, based on the total weight of the ethylene units and the other comonomer units of the vinyl acetate-ethylene copolymers, and

the free-radically initiated emulsion polymerization in the presence of

A) 0.5 to 20 wt .-%, based on the total weight of the total monomers used, of one or more solvents, or

B) 0.1 to 20 wt .-%, based on the total weight of the total monomers used, of one or more solvents and

0.5 to 4% by weight, based on the total weight of the total monomers used, of one or more anionic sulfosuccinic acid esters of the general formula

R ¹ -O-CO-CH ₂ -CH (SO ₃ M) -CO-O-R ¹ (I)

in which

M a cation,

R ^{1 is} a linear or branched alkyl radical having 4 to 17 carbon atoms, an alkylene oxide group - (R ² -O) _n -X or a cation M, where

R ^{2 is} a linear or branched alkylene unit having 2 to 5 C atoms,

n is equal to an integer value of 2 to 20 and

X is a linear or branched alkyl radical with 4 to

Stands 17 C atoms, wherein in the general formula (I) at most one radical R ^{1 is} a cation M.

2. A process for preparing vinyl acetate-ethylene ischpolymeri- saten according to claim 1, characterized in that anionic sulfosuccinic acid esters of the general formula (I) are selected from the group comprising Dioctylsulfusuccinate, diethyl hexylsulfosuccinates, Didecylsulfosuccinate, di-isotridecylsulfo- succinate, monoesters the sulfosuccinic acid ester of the general formula (I) in which R ^{1 is} - (R ² -O) _n -X and R ^{2 is} an alkylene unit having 2 C atoms, X is a linear or branched alkyl radical having 10 to 12 C Atoms and n is an integer from 3 to 6 and M is a cation, and diesters of the sulfosuccinic acid esters of the general formula (I) in which R ^{1 is} - (R ² -O) _n -X and R ^{2 is} an alkylene radical Unit having 2 C atoms, X is a linear or branched alkyl radical having 6 to 14 C atoms and n is an integer from 2 to 10 and M is a cation.

3. A process for the preparation of vinyl acetate-ethylene copolymers according to claim 1 or 2, characterized in that all radicals R ^{1 of} the anionic sulfosuccinic acid ester of the general formula (I) for linear or branched alkyl radicals having 4 to 17 carbon atoms or for Alkylene oxide groups - (R ² -O) _n -X.

4. A process for the preparation of vinyl acetate-ethylene isocyanates according to claims 1 to 3, characterized in that in process B) the anionic sulfosuccinic acid esters of general formula (I) in an amount of 11.1 to 80.0 wt .-%, based on the total weight of the protective colloids and anionic sulfosuccinic acid ester of the general formula (I), during the emulsion polymerization are present.

5. A process for the preparation of vinyl acetate-ethylene copolymers according to claim 1, characterized in that no emulsifier is used in process A).

6. A process for the preparation of vinyl acetate-ethylene copolymers according to claim 1 to 5, characterized in that one or more solvents are used selected from the group comprising alkyl alcohols such as methanol, ethanol, propanol diols or triols, and linear or cyclic Glycol ethers, such as diethylene or dipropylene glycol.

7. A process for the preparation of vinyl acetate-ethylene Mischpolymeri devices according to claim 1 to 6, characterized in that the protective colloids in an amount of a total of 1 to 7 wt .-%, based on the total weight of the monomers, during the emulsion polymerization are present ,

8. A process for the preparation of vinyl acetate-ethylene Mischpolymeri devices according to claim 1 to 7, characterized in that the vinyl acetate before initiation of the emulsion polymerization to 10 to 70 wt .-%, based on the total weight of the total vinyl acetate used, is submitted.

9. A process for the preparation of vinyl acetate-ethylene Mischpolymeri units according to claim 1 to 8, characterized in that the ethylene prior to initiation of the emulsion polymerization to 40 to 100 wt .-%, based on the total weight of the total ethylene used, is submitted.

10. A process for the preparation of vinyl acetate-ethylene Mischpolymeri units according to claim 1 to 4, characterized in that the emulsifiers are added to at least 25 wt .-%, based on the total weight of the total emulsifiers used, prior to initiation of the emulsion polymerization.

11. A process for the preparation of vinyl acetate-ethylene Mischpolymeri seten according to claim 1 to 10, characterized in that the vinyl acetate-ethylene copolymers keep no units of far ren comonomers and / or no units of auxiliary monomers ent.

12. Vinyl acetate-ethylene-Miachpolymerisate obtainable by the process of claims 1 to 11.

13. vinyl acetate-ethylene copolymers in the form of water-redispersible polymer powders obtainable by drying the products of the emulsion polymerization of the process according to claims 1 to 11.

14. Use of the process products of claims 1 to 11 or the vinyl acetate-ethylene copolymers according to claim 12 as or in adhesives for the bonding of cellulosic materials, such as paper, cardboard, wood, or plastics, such as polyethylene, polyvinyl chloride, polyamide, polyester, Polystyrene or acrylonitrile-butadiene-styrene.

15. Use of the process products of claims 1 to 11 or the vinyl acetate-ethylene copolymers according to claim 12 as a binder and / or coating agent for fibrous substances or structures, such as for nonwovens or fabric.