HK1116818A - Coating compositions with high scrub resistance, processes for producing them and use - Google Patents

Description

Coating compositions having high scrub resistance, method for producing them and use thereof

The present invention relates to novel coating compositions comprising an improved polyvinyl ester dispersion binder. The polymeric dispersions used in the present invention are useful in formulating coating compositions characterized by high scrub resistance.

With respect to polymeric dispersion formulations, the prior art has proposed a very wide variety of emulsifiers. For example, CH-A-436,721 describes a process for preparing lattices by emulsion polymerization of vinyl esters in the presence of α, β -unsaturated monocarboxylic acids. Suitable anionic emulsifiers are reported to include sulfosuccinate salts. In DE-A-19801442, a process for improving the stability of aqueous polymer dispersions when exposed to thermal and/or mechanical conditions is disclosed, which comprises adding to the aqueous polymer dispersion at least one sulfonated dicarboxylic acid bis-C having from 4 to 8 carbon atoms₄-C₁₈Salts of alkyl esters.

Coating compositions such as latex paints (dispersion based) are used for the protection of the interior and exterior surfaces of buildings. To ensure long life, the coating must be wash resistant.

The prior art has disclosed different methods for improving the washability of coatings.

For example, WO-A-98/33,831 describes the preparation of dispersions by two-stage polymerization and their use as binders for the formulation of coating compositions. The two-stage polymer is composed of a soft phase and a hard phase and a small proportion of comonomer units comprising carboxyl groups. In this example, styrene acrylate is described. The use of these binders results in improved blocking resistance and scrub resistance of the coating.

US-A-5,527,853 discloses storage stable and fast curing aqueous coating compositions. The composition includes an anionically stabilized emulsion polymer, a selected water-soluble polyfunctional amine polymer, and a volatile matrix.

US-B-6,242,531 describes acrylic resin-based aqueous miniemulsions which can be used as thickeners for latex paints.

US-B-6,646,058 describes aqueous coatings exhibiting improved hiding power and scrub resistance. The coating includes an acidic core-shell polymer and selected copolymers and pigments.

WO-A-99/36,444 discloses A process for improving the stability of aqueous polymer dispersions with respect to exposure to thermal and/or mechanical conditions. The method includes adding selected sulfonated dicarboxylic acid esters, such as sulfosuccinates, to the polymeric dispersion. Stabilized polyacrylate emulsions are described. Although the vinyl esters of choice are referred to as possible modifying comonomers, the disclosure does not include polyvinyl esters.

It is an object of the present invention to provide an aqueous emulsion coating comprising a binder based on a vinyl ester polymer which has been treated to give a coating having good scrub resistance.

It has now surprisingly been found that the above object can be achieved by using selected binders.

The present invention provides a coating composition comprising:

a) at least one pigment and/or filler, and

b) an aqueous dispersion of at least one vinyl ester polymer which has been copolymerized with ethylenically unsaturated monomers comprising silane groups and/or with ethylenically unsaturated epoxides and/or which has been stabilized with aminosilanes or epoxysilanes, which comprises as stabilizers thereof at least one nonionic emulsifier and at least one diester of a sulfonated dicarboxylic acid having 4 to 8 carbon atoms, preferably a bis-C₄-C₁₈Mixtures of salts of alkyl esters.

As component a), the coating compositions of the invention comprise pigments and/or fillers. These are finely divided solids which are organic or inorganic in nature, colored or natural.

Examples of pigments are inorganic pigments, such as inorganic oxides or inorganic sulfides or carbon black or organic pigments. Preferred examples of pigments are titanium dioxide, zinc oxide, zinc sulphide, iron oxide and/or carbon black or organic pigments. Particularly preferred is titanium dioxide.

Examples of fillers are carbonates such as dolomite, calcite and chalk. Other examples are silicates such as talc, kaolin, china clay and mica. Calcium carbonate and mica are preferred.

Particularly preferred components a) are titanium dioxide and/or calcium carbonate.

The fraction of component a) in the coating composition of the invention is generally from 22% to 70%, preferably from 32% to 60%, more particularly from 45% to 60%, based on the total amount of solids by weight.

The vinyl ester polymer component b) is a polymer prepared by free radical emulsion polymerization, comprising at least 40 mol%, based on the total amount of monomers used, of a vinyl ester monomer or a mixture of vinyl ester monomers, the vinyl ester polymer being copolymerized with an ethylenically unsaturated monomer comprising a silane group and/or with an ethylenically unsaturated epoxide and/or the vinyl ester polymer being modified with an aminosilane or epoxysilane.

The vinyl esters generally include those having C₁-C₄Esters of aliphatic saturated carboxylic acids of chain length.

The vinyl ester polymers used are preferably derived from:

A1) having a structure of C₁-C₄Vinyl esters of aliphatic saturated carboxylic acids of chain length,

A2) an alpha-olefin having 2 to 8 carbon atoms, and/or

A3) Chain length of aliphatic saturation is C₅-C₁₈Vinyl esters of carboxylic acids, more particularly alpha-branched carboxylic acids having 5 to 11 carbon atoms in the acid radical ((II))^®Versatic acid), and

A4) ethylenically unsaturated monomers and/or ethylenically unsaturated epoxides comprising silane groups, and

A5) if desired, the other comonomers,

the sum of the monomers of type A1, A4, A2 and/or A3, and, if desired, A5, amounts to 100% by weight.

Preferred vinyl ester copolymers are preferably derived from the types A1, A2, A4 and if desired

A5) Type monomers, or monomers of type a1, A3, a4 and if desired a5), or more preferably monomers from the type a1, a2, A3, a4 and if desired a 5).

Chain length C₁-C₄The vinyl esters A1 of aliphatic saturated carboxylic acids are vinyl esters of straight-chain or branched aliphatic carboxylic acids, examples being vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate or vinyl isobutyrate. Vinyl acetate is preferred. In the polyvinyl esters, the vinyl esters A1 can also be present in combinations of two or more thereof together with one another.

The monomer a1, if suitably combined with additional comonomers from this group, has a fraction of monomer a1 of from 40% to 95% by weight, preferably from 50% to 76% by weight, based on the total amount of monomers used by weight.

Alpha-olefins having from 2 to 8 carbon atoms, A2 being branched or straight-chain alpha-olefins, examples being prop-1-ene, but-1-ene, pent-1-ene, hex-1-ene, hept-1-ene, oct-1-ene, more particularly ethylene.

Monomer A2, wherein the fraction of monomer A2, when suitably combined with other comonomers from this group, is from 0% to 45% by weight, preferably from 5% to 45% by weight, more preferably from 8% to 25% by weight, very preferably from 10% to 20% by weight, based on the total amount of monomers used by weight.

Chain length C₅-C₁₈Vinyl esters A3 of aliphatic saturated carboxylic acids are vinyl esters of straight-chain, or preferably branched, aliphatic carboxylic acids, examples being alpha-branched carboxylic acids having 5 to 11 carbon atoms in the acid radical ((R))^®Versatic acids), vinyl esters of pivalic acid, 2-ethylhexanoate, lauric acid, palmitic acid, myristic acid and stearic acid. Preferably a vinyl ester of a branched alkane carboxylic acid, more particularly VeoVa ® 9,VeoVa ® 10, and VeoVa ® 11. In the polyvinyl esters, the vinyl esters A3 can also be present in combinations of two or more thereof together with one another.

Monomer A3, wherein the fraction of monomer A3, when suitably combined with other comonomers from this group, is from 2% to 60% by weight, preferably from 2% to 40% by weight, more preferably from 4% to 30% by weight, and very preferably from 5% to 25% by weight, based on the total amount of monomers used by weight.

The ethylenically unsaturated monomer A4 comprising a silane group is generally of the formula RSi (CH)₃)_0-2(OR¹)_3-1Wherein R is defined as CH₂＝CR²-(CH₂)_0-1Or CH₂＝CR²CO₂-(CH₂)_1-3，R¹Is unbranched or branched, unsubstituted or substituted alkyl having 1 to 12 carbon atoms which is interrupted, if desired, by ether groups, R²Is H or CH₃。

Preferably of the formula CH₂＝CR²-(CH₂)_0-1Si(CH₃)_0-1(OR¹)_3-2And CH₂＝CR²CO₂-(CH₂)₃Si(CH₃)_0-1(OR¹)_3-2Silane of (2), R¹Is a branched or unbranched alkyl radical having from 1 to 8 carbon atoms, R²Is H or CH₃。

Particularly preferred silanes are vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldi-n-propoxysilane, vinylmethyldiisopropyloxysilane, vinylmethyldi-n-butoxysilane, vinylmethyldi-sec-butoxysilane, vinylmethyldi-tert-butoxysilane, vinylmethyldi (2-methoxyisopropoxy) silane and vinylmethyldioctyloxysilane.

More particularly preferred is the formula CH₂＝CR²-(CH₂)_0-1Si(OR¹)₃And CH₂＝CR²CO₂-(CH₂)₃Si(OR¹)₃Silane of (2), R¹Is a branched or unbranched alkyl radical having from 1 to 4 carbon atoms, R²Is H or CH₃。

Examples thereof are γ - (meth) acryloyloxypropyltri (2-methoxyethoxy) silane, γ - (meth) acryloyloxypropyltrimethoxysilane, γ - (meth) acryloyloxypropyltriethoxysilane, γ - (meth) acryloyloxypropyltri-n-propoxysilane, γ - (meth) acryloyloxypropyltriisopropoxysilane, γ - (meth) acryloyloxypropyltributoxysilane, γ -acryloyloxypropyltri (2-methoxyethoxy) silane, γ -acryloyloxypropyltrimethoxysilane, γ -acryloyloxypropyltriethoxysilane, γ -acryloyloxypropyltri-n-propoxysilane, γ -acryloyloxypropyltriisopropoxysilane, γ -acryloyloxypropyltributoxysilane, and vinyltris (2-methoxyethoxy) silane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltriisopropoxysilane and vinyltributoxysilane. The silane compounds mentioned can, if appropriate, also be used in the form of their (partial) hydrolysates.

In addition to or instead of the ethylenically unsaturated silane, an ethylenically unsaturated epoxide, such as glycidyl methacrylate or glycidyl acrylate, can be used as monomer a 4.

Monomer A4, if suitably combined with additional comonomers from this group, has a fraction of monomer A4 of from 0.1% to 10% by weight, preferably from 0.5% to 5% by weight, based on the total amount of monomers used by weight.

Other silanes, such as aminosilanes or epoxysilanes, may be added to the coating compositions of the present invention in addition to or in place of monomer A4. This can be done during the preparation of the copolymer or more particularly after the preparation of the copolymer.

Suitable comonomers of group a5 preferably have at least one nonionic or ionic stabilizing group, preferably an acid group, in the molecule, which further stabilizes the emulsion polymer via the polymer-attached functional groups and/or charges.

Suitable comonomers A5 having stable nonionic groups include, in particular, esters of ethylenically unsaturated aliphatic monocarboxylic and/or dicarboxylic acids with polyglycols, preferably with polyethylene glycol and/or polypropylene glycol, or esters of ethylenically unsaturated carboxylic acids with amino alcohols, such as (meth) acrylates of amino alcohols, for example diethylaminoethanol, and/or with dimethylaminoethanol, and also (meth) acrylates having a chain length C₂-C₁₈(meth) acrylic acid esters of dihydric aliphatic alcohols in which only one alcohol group is esterified. Also suitable are amides of ethylenically unsaturated carboxylic acids, such as the amides of acrylic acid and methacrylic acid, and the N-methylolamides of acrylic acid and methacrylic acid, and also their ethers. Another group of these monomers are N-vinylamides, including N-vinyllactams, examples being vinylpyrrolidone or N-vinyl-N-methylacetamide.

Suitable comonomers a5 having stabilizing ionic groups are ethylenically unsaturated carboxylic or sulfonic acids having one or two carboxyl groups or one sulfonic acid group. Instead of the free acids, it is likewise possible to use their salts, preferably alkali metal or ammonium salts.

Examples of comonomers A5 are acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, vinylsulfonic acid, styrenesulfonic acid, maleic acid and/or fumaric acid and itaconic acid with a chain length C₁-C₁₈And alkali metal salts and ammonium salts thereof or (meth) acrylic acid salts of thioalkanols of (a), an example being sodium 2-thioethyl methacrylate.

As further comonomers a5 which can be used in the copolymer, any desired comonomer can be used which does not belong to group a1, a2, A3 or a 4. An example of this is a chain length C₃-C₁₂With a chain length of C₃-C₁₈Esters of unsaturated alcohols, chlorineEthylene, vinylidene chloride, acrylonitrile, methacrylonitrile, butadiene, isoprene, C₉-C₁₆Alpha-olefin of (A), 2-chloroprene, 2, 3-dichlorobutadiene, tetrafluoroethylene, styrene, chain length C₁-C₁₈With a chain length of C₃-C₁₈Of saturated and unsaturated aliphatic dicarboxylic acids, vinyl esters and allyl esters of acrylic acid and crotonic acid and triallyl cyanurate. Preferred further comonomers A5 are those having a chain length C₄-C₈Acrylic esters or C of monohydric aliphatic saturated alcohols₁₄-C₁₆Alpha-olefins or butadiene.

Any further comonomer a5 is contained, if appropriate in combination with further comonomers from this monomer group, in an amount of generally up to 10%, preferably up to 8%, based on the total amount of copolymer composition a).

In the polyvinyl esters, the comonomer a5 may also be present in combinations of two or more thereof together with one another.

In addition to the above-mentioned monomer groups a1, a2, A3 and a4, or a1, a2 and a4, or a1, A3 and a4, it is preferred to use at least one further comonomer of group a5, more particularly vinylsulfonic acid or an alkali metal salt thereof.

Component b) is further characterized by a selected composition containing an emulsifier. These are the nonionic emulsifier E1 and the selected anionic emulsifier E2. They are added even before or during the emulsion polymerization; however, portions thereof may also be added subsequently. Component b) used in the present invention does not comprise a protective colloid. Thus no emulsion stabilizing polymers, such as polyvinyl alcohol or cellulose ethers, are present during the emulsion polymerization. However, it is possible for such components to be added subsequently.

Component b) preferably does not comprise an emulsion-stabilizing polymer.

Examples of nonionic emulsifiers E1 are acyl, alkyl, oleyl and alkylaryl ethoxylates. These products are known, for example, under the name Genapol ®Or Lutensol ®. They include, for example, ethoxylated mono-, di-and trialkylphenols (EO degree: 3 to 50, alkyl substituents: C₄-C₁₂) And ethoxylated fatty alcohols (EO degree: 3-80; alkyl groups: c₈-C₃₆) In particular C₁₂-C₁₄Fatty alcohol (3-8) ethoxylate, C₁₃C₁₅Oxo-process for alcohol (3-30) ethoxylates, C₁₆C₁₈Fatty alcohol (11-80) ethoxylate, C₁₀Oxo Process alcohol (3-11) ethoxylate, C₁₃Oxo alcohol (3-20) ethoxylates, polyoxyethylene sorbitan monooleate having 20 ethylene oxide groups, copolymers of ethylene oxide and propylene oxide having an ethylene oxide content of a minimum of 10% by weight, polyethylene oxide (4-20) ethers of oleyl alcohol, and polyoxyethylene (4-20) ethers of nonylphenol. Particularly suitable are polyethylene oxide (4-20) ethers of fatty alcohols, more particularly oleyl alcohol.

The nonionic emulsifier E1 is generally used in amounts of from 0.1 to 5 parts by weight, preferably from 0.5 to 3.0 parts by weight, based on the vinyl ester polymer. Mixtures of nonionic emulsifiers E1 can also be used.

As emulsifier mixture for the further component E2, diesters, preferably bics, are used₄-C₁₈Salts of alkyl esters, salts of sulfonated dicarboxylic acids having 4 to 8 carbon atoms, or mixtures of these salts.

These are preferably sulfonated salts of succinic acid esters, more preferably sulfosuccinic acid bis-C₄-C₁₈Salts of alkyl esters, such as alkali metal salts.

Examples of particularly preferred emulsifiers of type E2 are sulfosuccinic acid and chain length C₄-C₁₆Alkali metal salts of aliphatic saturated monoalcohol esters of (A), sulfosuccinic acid and chain length C₁₀-C₁₂Alkali metal salts (disodium salts) of polyglycol ether 4-esters of monohydric aliphatic alcohols, alkali metal salts (disodium salts) of sulfosuccinic acid with polyglycol nonylphenol ether 4-esters, or alkali metal salts (sodium salts) of dicyclohexyl sulfosuccinate.

Based on the vinyl ester polymer, generally from 0.1 to 5.0 parts by weight, preferably from 0.5 to 3.0 parts by weight, of nonionic emulsifier E2 are used. Mixtures of anionic emulsifiers E2 can also be used.

To further improve the stability, other anionic stabilizers can likewise be used as coemulsifiers. Mention may be made, for example, of the chain length C₁₂-C₂₀Sodium, potassium and ammonium salts of straight-chain aliphatic carboxylic acids, sodium hydroxyoctadecanesulfonate, chain length C₁₂-C₂₀Sodium, potassium and ammonium salts of hydroxy fatty acids, their products of sulfonation and/or acetylation, alkyl sulfates, including those in the form of triethanolamine salts, alkyl (C)₁₀-C₂₀) Sulfonates, alkyl (C)₁₀-C₂₀) Aryl sulfates, dimethyl dialkyl (C)₈-C₁₈) Ammonium chloride, their sulfonated products, lignosulfonic acid and its calcium, magnesium, sodium and ammonium salts, resin acids, hydrogenated and dehydrogenated resin acids, and their alkali metal salts, sodium dodecyl diphenyloxide disulfonate, sodium dodecyl sulfate, or sodium ethoxylated lauryl ether sulfate (EO degree 3). From 0 to 5.0 parts by weight, preferably from 0 to 3.0 parts by weight, based on the vinyl ester polymer, of a further ionic emulsifier E3 is generally used. Mixtures of these further anionic emulsifiers E3 can also be used.

The nonionic emulsifiers E2 are generally used in fractions of from 0.2 to 10 parts by weight, preferably from 0.5% to 5.0% by weight, based on the vinyl ester polymer.

The weight fractions of emulsifiers E1-E2 vary within wide limits, for example from 1: 10 to 10: 1.

The fraction of component b) of the coating composition of the invention is generally from 6% to 55% by weight, preferably from 15% to 30% by weight, based on the total solids content by weight.

The aqueous polyvinyl ester dispersions used in the present invention generally contain from 20% to 70% by weight, preferably from 30% to 65% by weight, and more preferably from 40% to 60% by weight of solid constituents.

Preference is given to those coating compositions in which the vinyl ester polymer is derived from monomers of the above-defined types A1, A2, A4, and, if desired, A5, wherein the monomer of type A2 is ethylene. A particularly preferred copolymer from this group is a vinyl acetate-ethylene copolymer which has been modified with monomers comprising silane groups and/or with monomers comprising epoxy groups.

Further preferred are coating compositions wherein the vinyl ester polymer is derived from monomers of the above defined types a1, A3, a4, and if desired a5, wherein the monomers of type A3 are vinyl esters of alpha-branched carboxylic acids having 9 to 11 carbon atoms in the acid group (® versatic acid), which have been modified with monomers comprising silane groups and/or with monomers comprising epoxy groups.

Particularly preferred coating compositions comprise a polymeric dispersion in which the stabilizer mixture comprises from 1% to 10% by weight, based on the monomers used, and in which the weight ratio of nonionic emulsifier to ionic emulsifier is from 1: 10 to 10: 1.

The coating compositions of the invention also comprise typical additives c), if desired.

As additives and further constituents, film-forming auxiliaries, such as, for example, white spirit, Texanol^®、TxiB^®Butyl glycol, butyl diethylene glycol, butyl dipropylene glycol and butyl tripropylene glycol; plasticizers, e.g. dimethyl phthalate, diisobutyl adipate, Coasol B^®And Plastilit 3060^®(ii) a Wetting agents, such as AMP 90^®、TegoWet 280^®And Fluowet PE^®(ii) a Thickeners, such as polyacrylates or polyurethanes, e.g. Borchigel L75^®And Tafigel PUR60^®(ii) a Defoamers, such as mineral oil defoamers or silicone defoamers; UV stabilizers, e.g. Tinuvin 1130^®Subsequently, a stabilizing polymer, such as polyvinyl alcohol or cellulose ether, and further additives and auxiliaries of the type typically used in coating formulations.

The fraction of component c) in the coating composition of the invention is up to 25% by weight, preferably from 2% by weight to 15% by weight, more particularly from 5% by weight to 10% by weight, based on the total amount of solid constituents by weight of the coating composition.

The minimum film-forming temperature of the coating composition of the invention is generally less than 25 c, preferably less than 15 c. The film forming temperature can be modified and adjusted by adding conventional coalescents.

The invention also relates to a process for preparing the above-described aqueous coating composition. The method comprises the following steps: comprising at least one nonionic emulsifier and at least one diester of a sulfonated dicarboxylic acid having 4 to 8 carbon atoms, preferably bis-C₄-C₁₈Preparation of a polyvinyl ester dispersion which has been copolymerized with ethylenically unsaturated monomers comprising silane groups and/or with ethylenically unsaturated epoxides and/or which has been modified with aminosilanes or epoxysilanes by free-radical emulsion polymerization in the presence of an emulsifier mixture of salts of alkyl esters, the mixing of the above-defined components a), b) and, if desired, c) being effected, for example, by stirring the copolymer dispersion described, together with a pigment/filler paste, in a Lenard mixer at a speed of 1500 rpm.

A particularly preferred embodiment of the process according to the invention comprises preparing component b) by free-radical emulsion polymerization in the presence of a stabilizer mixture consisting of at least one nonionic emulsifier and at least one salt of a sulfonated dicarboxylic diester having 4 to 8 carbon atoms to give a vinyl acetate-ethylene copolymer which has been modified with monomers comprising silane groups and/or with monomers comprising epoxide groups.

Component b) is generally prepared by free-radical emulsion polymerization. This can be done in a batch process, a feed process, a combined batch/feed process, or a continuous process.

Preference is however given to operating in a combined batch/feed process, with preference being given to operating in the feed process, and in this case a portion of the monomers (1% to 15% by weight) is generally first introduced at the beginning of the polymerization. The monomers can be metered either together or in separate feeds. It is also advantageous in particular embodiments to carry out the seed polymerization in order to adjust a particular particle size and particle size distribution.

Examples of free radical initiators used include the following: hydrogen peroxide, benzoyl peroxide, cyclohexanone peroxide, isopropylcumyl hydroperoxide, persulfates of potassium, sodium and ammonium, having a chain length C₈-C₁₂Peroxides of an even number of saturated monobasic aliphatic carboxylic acids, tert-butyl hydroperoxide, di-tert-butyl peroxide, diisopropyl percarbonate, azobutanedinitrile, acetylcyclohexanesulfonyl peroxide, tert-butyl perbenzoate, tert-butyl peroctoate, bis (3, 5, 5-trimethyl-hexanoyl) peroxide, tert-butyl peroxytrimethyl acetate, pinane hydroperoxide, p-menthane hydroperoxide. It is also possible to use the above-mentioned compounds in redox systems, in which case transition metal salts such as iron (11) salts or other reducing agents are used. As reducing agents or regulators, it is possible to use alkali metal salts of hydroxymethanesulfinic acid having a chain length C₁₀-C₁₈Alkali metal salts of mercaptans, but-1-en-3-ol, hydroxylamine salts, sodium dialkyldithiocarbamate, sodium bisulfite, ammonium bisulfite, sodium dithionite, diisopropyl xanthogen disulfide, ascorbic acid, tartaric acid, erythorbic acid, boric acid, carbonamides and formic acid.

Preferably, however, a water-soluble persulfate salt, more particularly ammonium persulfate or sodium persulfate, is used to initiate polymerization.

The emulsifier mixture used for stabilization can likewise be added in its entirety at the beginning of the polymerization, or be contained in part in the initial charge, be metered in part during the polymerization, or be metered in completely during the polymerization.

The pH of the dispersion is generally from 2 to 7, preferably from 2.5 to 6.

The polymerization temperature is generally from 20 to 120 ℃ and preferably from 30 to 110 ℃ and very preferably from 45 to 95 ℃.

To remove the monomer effect, the polymerization is subsequently subjected to a further aftertreatment, preferably a chemical aftertreatment, more particularly a treatment with redox catalysts, such as the abovementioned oxidizing and reducing agent compositions. In addition, the residual monomers can be removed by known methods: for example by physical demonomerization, i.e. distillative removal (more particularly via steam distillation), or by stripping with inert gases. Particularly efficient is a combination of physical and chemical processes which can reduce residual monomers to very low levels (< 1000ppm, preferably < 100 ppm).

The aqueous coating compositions of the invention, for example in the form of coatings, are suitable for a wide variety of coated substrates which are preferably suitable in the construction sector.

The present invention also provides these uses.

The present invention further provides the use of the aqueous vinyl ester dispersions defined above as binders for aqueous coating compositions, more particularly for aqueous emulsion coatings.

The following examples serve to illustrate the invention. Parts and percentages in the examples are by weight unless otherwise indicated.

Comparative example 1

Non-inventive useful vinyl acetate/ethylene copolymer dispersions were prepared and the remaining monomers were subsequently removed.

The pressure apparatus with stirrer, heating jacket and metering pump was filled with an aqueous solution consisting of:

22000g of water, 86g of sodium acetate, 1440g of a 70% strength by weight aqueous solution of an alkyl ethoxylate from oxo process containing 28mol of ethylene oxide, 2160g of a 10% strength by weight aqueous polyvinyl alcohol solution (4% strength by weight aqueous solution having a viscosity of 18mPa), 1127g of a 15% strength by weight sodium lauryl sulfate solution, 577g of a 30% strength by weight aqueous solution of sodium vinylsulfonate, and 8g of 1 wt% Fe-11 (SO-SO)₄)×7H₂An aqueous solution of O. The pH of the solution was 7.2. The apparatus is free of atmospheric oxygen and is filled with ethylene. 1500g of vinyl acetate were metered in at an ethylene pressure of 20 bar. Heating to an internal temperature of 60 deg.C, during the heating, BThe olefin pressure rises to 40 bar. A solution of 10% of 27.1g of Bruggolit C in 2000g of water is then metered in. Subsequently, a solution of 10% 27.1g of tert-butyl hydroperoxide in 2000g of water is metered in at an internal temperature of 60 ℃ and cooled to remove the heat of reaction. A mixture of 28800g of vinyl acetate and 70g of Vinyltrimethoxysilane (VTM) and the remaining 90% of the reducing solution and initiator solution is then metered in, and the ethylene pressure is maintained at 40 bar until 4135g of ethylene are present in the reactor. Thereafter, a solution of 36g of sodium persulfate in 600g of water was metered in, and the internal temperature was raised to 80 ℃ and held at this temperature for 1 hour. Subsequently, under stirring, the major part of the unreacted ethylene was removed and 2L of water were added. Then, 2L of water were distilled off within 2 hours with the application of vacuum, so that the residual vinyl acetate content of the dispersion was reduced to 0.05% by weight, based on the dispersion. The separation step was repeated to achieve a residual vinyl acetate content of 0.012 wt%.

Some properties of the resulting dispersion are shown in Table 1.

Examples 2 to 10 of the present invention

Vinyl acetate-ethylene or vinyl acetate-VeoVa 10 copolymer dispersions useful in the present invention were prepared and subsequently the remaining monomers and other volatile components were removed.

Polymerization was carried out in the same apparatus by the same method as in comparative example 1, but with a different composition as listed in the following table, in which 1127g of a 15% by weight solution of sodium lauryl sulfate were replaced by the sodium salt of sulfosuccinic acid ester (all values are expressed as% by weight solids based on vinyl acetate/VeoVa 10 or on vinyl acetate/ethylene).

Table 1: composition of the Polymer Dispersion produced

	Vinyl acetate (VAA)	VeoVa10	Ethylene	Ethylene sulfonic acid sodium salt	VTM	Polyvinyl alcohol	Oxo process for alkyl ethoxylate-28 EO	Sodium sulfosuccinate
									C1	88	0	12	0.5	0.2	0.6	3	0
2	88	0	12	0.5	0.2	0	3	1
									3	88	0	12	0.5	0.2	0	2	1
4	88	0	12	0.5	0.2	0	3	1.75
									51)	88	0	12	0.5	0.2	0	3	1
6	75	25	0	0.5	0.2	0	0.5	3
									7	75	25	0	0.5	0.2	0	2	1
8	75	25	0	0.75	0.2	0	3	3
									9	75	25	0	0.75	0.2	0	0.5	0.5
10	75	25	0	0.5	0.2	0	3	0.5

1) Polymerization at 50 deg.C

Table 2: physical Properties of the Polymer dispersions prepared

	Solids%	Particle size [ nm ]]
			C1	54	200

2	54.1	163
			3	54.2	159
4	54	147
			5	53.6	144
6	53.8	189
			7	53.7	187
8	53.5	146
			9	52.3	233
10	53.4	185

The polyvinyl ester dispersions used according to the invention are characterized by a lower average particle size and a narrower particle size distribution than dispersions stabilized with protective colloids. Using the soft dispersions C1 and 2-5, coatings of the solvent-free general formula (Table 3) were prepared, and using the hard dispersions, coatings of the solvent-containing general formula (Table 5) were prepared.

Application examples

The invention is described in more detail below by means of a latex paint formulation having the following composition.

TABLE 3

Composition (I)	Parts by weight
		Water (W)	301.5
Dispersing agent (sodium polyphosphate, 10% solution)	5.0
		Cellulose ether (type MH, high viscosity)	4.0
	3.5
		Mineral oil-based defoaming agent	2.0
10% strength aqueous sodium hydroxide solution	2.0
		Titanium dioxide pigment	80.0
Filler, calcium carbonate, particle size 2 microns	235.0
		Filler, calcium carbonate, particle size 5 microns	205.0

Aluminium silicate filler	35.0
		Copolymer dispersion 1)	125.0
Preservative	2.0

1) Using the copolymers of examples C1 and 2-5 (see Table 1)

Methylhydroxyethyl cellulose in powder form is dispersed in water and dissolved with stirring, after which a sodium salt solution of polyacrylate and polyphosphoric acid and a 10% strength by weight aqueous sodium hydroxide solution are added with stirring. The preservative and defoamer were mixed to give a viscous solution. The aluminium silicate was introduced first at a stirring speed of 2000rpm, with stirring by means of a dissolver, and then the titanium dioxide and the radial calcium carbonate were added with the stirrer speed increasing to 5000 rpm. The dispersion was continued at 5000rpm for 20 minutes and the temperature of the pigment/filler paste was raised to 60 ℃. Cooled to 30 ℃. The pH was 9.3.

To investigate the parameters of the described copolymer dispersions 875g of pigment/filler paste were stirred with 125g of each of the copolymer dispersions tested (3 minutes, Lenard stirrer, 1500 rpm). The resulting latex paint had a solids content of about 63% by weight and a Pigment Volume Concentration (PVC) of about 77%.

The scrub resistance of these coatings was tested by the nonwoven insertion method (ISO 11998). For this purpose, the coating abrasion (amount) due to the loss of the coating film amount after 28 days was determined. The paint abrasion in μm was then calculated from the paint density, the scrub surface area and the amount of film loss.

The main properties of different latex paints are the scrub resistance (WSR) and hiding power. The test results are shown in table 4.

TABLE 4

Copolymers of the examples	WSR[μm]	Hiding power
			C1	30	98.3
2	23	98.3
			3	25	98.8

4	22	98.2
			5	20	98.3

As described above, the copolymers of examples 6-10 were used to prepare latex paints having the following compositions:

TABLE 5

Water (W)	285.5
		Dispersant (sodium salt of polyacrylic acid) cellulose ether MH 10000 YP 2 dispersant (sodium polyphosphate) 10% defoamer microsilica filler aluminum silicate filler Kronos 2065 titanium dioxide calcium carbonate filler, preservative of particle size 5 microns Ammonia concentration (25%) copolymer Dispersion Texanol (solvent)	3.04.515.00.540.040.070.0440.01.50.580.020.01000.0

Latex paints were prepared as described in the formulation in table 3.

The test results are shown in table 6 below.

TABLE 6

Copolymers of the examples	WSR1)[μm]	Hiding power2)
			C1	35	98.3
6	26	98.5

7	23	98.3
			8	25	98.8
9	28	98.2
			10	29	98.3

1) WSR is scrub resistance; number is mum

2) The hiding power was determined in accordance with DIN ISO 6504-3.

Claims (16)

1. A coating composition comprising:

a) at least one pigment and/or filler, and

b) an aqueous dispersion of at least one vinyl ester polymer which has been stabilized with ethylenically unsaturated monomers comprising silane groups and/or with ethylenically unsaturated epoxides and/or with emulsifiers which have been modified with aminosilanes or epoxysilanes, comprising as stabilizers thereof a mixture of at least one nonionic emulsifier and at least one salt of a sulfonated dicarboxylic acid diester having 4 to 8 carbon atoms.

2. The coating composition of claim 1, wherein the vinyl ester polymer is derived from:

A1) chain length of C₁-C₄Of an aliphatic saturated carboxylic acid of (a),

A2) an alpha-olefin having 2 to 8 carbon atoms, and/or

A3) Chain length of C₅-C₁₈Vinyl esters of aliphatic saturated carboxylic acids, and

A4) ethylenically unsaturated monomers and/or ethylenically unsaturated epoxides comprising silane groups, and

A5) if desired, the other comonomers,

the sum of the monomers of type A1, A4, A2 and/or A3, and, if desired, A5, amounts to 100% by weight.

3. The coating composition of claim 2, wherein the monomer of type a1 is vinyl acetate.

4. The coating composition of claim 2, wherein the vinyl ester polymer is derived from monomers of type a1, a2 and a4, if desired a5, wherein the monomer of type a2 is ethylene, preferably a vinyl acetate-ethylene copolymer modified with a monomer comprising a silane group and/or with a monomer comprising an epoxy group a 4.

5. The coating composition of claim 2 wherein the vinyl ester polymer is derived from monomers of type a1, A3, and a4, if desired a5, wherein the monomer of type A3 is a vinyl ester of an alpha-branched carboxylic acid (® Versatic acid) having 9 to 11 carbon atoms in the acid group.

6. The coating composition of claim 2, wherein the vinyl ester polymer comprises monomer units derived from ethylenically unsaturated monomers of type a4 comprising silane groups, wherein monomer a4 is of the formula CH₂＝CR²-(CH₂)_0-1Si(CH₃)_0-1(OR¹)_3-2And/or CH₂＝CR²CO₂-(CH₂)₃Si(CH₃)_0-1(OR¹)_3-2Silane of (2), R¹Is a branched or unbranched alkyl radical having from 1 to 8 carbon atoms, R²Is H or CH₃。

7. The coating composition of claim 2, wherein the vinyl ester polymer comprises monomer units derived from a monomer comprising an ethylenically unsaturated epoxide monomer of type a4, wherein monomer a4 is glycidyl methacrylate or glycidyl acrylate.

8. The coating composition of claim 1, wherein the non-ionic emulsifier is selected from the group consisting of acyl, alkyl, oleyl and alkylaryl ethoxylates, more particularly ethoxylated mono-, di-and trialkylphenols, ethoxylated fatty alcohols, and copolymers of ethylene oxide and propylene oxide with an ethylene oxide content of a minimum of 10 wt%.

9. The coating composition of claim 1, wherein the salt of a diester of a sulfonated dicarboxylic acid having 4 to 18 carbon atoms is sulfonated succinic acid bis-C₄-C₁₈Salts of alkyl esters, preferably alkali metal salts.

10. The coating composition of claim 1, wherein the stabilizer mixture comprises from 1% to 10% by weight, based on the monomers used, and wherein the weight ratio of nonionic emulsifier to ionic emulsifier is from 1: 10 to 10: 1.

11. The coating composition of claim 1, wherein component a) is selected from inorganic oxides, inorganic sulfides, carbon black, inorganic carbonates and organic pigments, more particularly from titanium dioxide and/or calcium carbonate.

12. A method of producing the aqueous emulsion coating of claim 1 comprising: at least one ofThe diester of a non-ionic emulsifier and at least one sulfonated dicarboxylic acid having 4 to 8 carbon atoms, preferably a di-C₄-C₁₈The polyvinyl ester dispersions which have been copolymerized with ethylenically unsaturated monomers comprising silane groups and/or ethylenically unsaturated epoxides and/or which have been modified with aminosilanes or epoxysilanes are prepared by free-radical emulsion polymerization in the presence of an emulsifier mixture of salts of alkyl esters, the resultant polyvinyl ester dispersions being mixed in a conventional manner with at least one pigment and/or filler and, if desired, further conventional additives.

13. The process of claim 12, wherein as component b) vinyl acetate-ethylene copolymers modified with monomers comprising silane groups and/or with monomers A4 comprising epoxide groups in the presence of bis-C of at least one nonionic emulsifier and at least one sulfonated dicarboxylic acid having from 4 to 8 carbon atoms are used₄-C₁₈Prepared by free radical emulsion polymerization in the presence of a stabilizer mixture consisting of a salt of an alkyl ester.

14. Use of the aqueous coating composition of claim 1 to coat various substrates.

15. Use according to claim 1, wherein the aqueous coating composition is a coating for the building sector.

16. Use of the aqueous vinyl ester dispersion according to claim 1 as a binder for aqueous coating compositions, more particularly for aqueous emulsion coatings.