WO1995014700A1

WO1995014700A1 - Novel siloxanes and methods for the preparation thereof, the use of siloxanes in coating compositions, the coating compositions thus obtained and the use of said coating compositions in coating substrates or products, together with the substrates and products thus coated

Info

Publication number: WO1995014700A1
Application number: PCT/NL1994/000297
Authority: WO
Inventors: Hendrikus Alfonsus Molenaar; Franky Flory Vercauteren; Aloijsius Henricus Antonius Tinnemans
Original assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
Priority date: 1993-11-25
Filing date: 1994-11-25
Publication date: 1995-06-01
Also published as: NL9302042A

Abstract

The invention relates to siloxanes, of which at least one group is directly bound, via a carbon atom, to the silicon atom, and of which at least one of the silyloxy groups has an electronegative character. The invention further relates to the use of these siloxanes in the preparation of coating compositions and to coating compositions which contain these siloxanes. The coating composition preferably comprises a water-based dispersion paint.

Description

Novel siloxanes and methods for the preparation thereof, the use of siloxanes in coating compositions, the coating compositions thus obtained and the use of said coating compositions in coating substrates or products, together with the substrates and products thus coated.

The present invention relates to novel siloxanes, to methods for the preparation of said siloxanes and to the use of said siloxanes in the preparation of coating compositions. The invention further relates to coating compo¬ sitions which contain one or more of said siloxanes, to the use of said coating compositions in coating sub¬ strates and products, and to substrates and products which have been coated with said coating compositions. German Offenlegungsschrift 3 023 620 describes organosilane compounds of the formula

in which R¹ is a monovalent hydrocarbon group with 1-8 carbon atoms, R², R³ and R⁴ are independently a hydrogen atom or a monovalent hydrocarbon group with 1-8 carbon atoms, m equals 3, 4 or 5, and n equals 0, 1 or 2.

These compounds are used as adhesion promotors for adhesives.

The use of said al oxysilanes in coating composi¬ tions, wherein the alkoxysilanes are built in chemically into the polymer during the polymerisation process so as to provide for post-application cross-linking, is neither described nor suggested.

It is known in the art of water-based emulsion paints that the presence of a post-application cross- linking mechanism in aqueous coating compositions offers major advantages with regard to the quality and the ultimate properties of the dried emulsion paint, such as a greater wear resistance, impact resistance, flexural strength and tensile strength, and hardness. The use of a post-application cross-linking mechanism also has environmental advantages. Thus the emission of organic solvents is restricted because, owing to the presence of the post-application cross-linking mechanism, no coales- cents - i.e. organic solvents - are required for film formation, and because the final layer of paint can generally be removed by sanding, without strippers containing organic solvent being required in the process. According to the literature, the incorporation of a post-application cross-linking mechanism into one-pack paints, such as acrylic paints which harden at room temperature, is achieved by using alkoxysilanes. In this case, the post-application cross-linking arises from the formation of grafting links from the alkoxysilane monomers.

In addition to the ready formation of said grafting links, the use of alkoxysilanes in paint compositions provides other advantages, which are specifically related to the presence of silyl ethers in the coating, such as improved adhesion, better wetting of both the substrate and the pigment and filler particles, reduced water sensitivity and reduced discoloration.

The alkoxysilyl-containing latices known from the prior art, however, suffer from the typical problem of premature cross-linking during emulsion polymerization and during storage in the pot, which is connected with the excessive hydrolysis of the silyl ether bonds in the alkoxysilanes. As a result, the shelf life and the industrial and practical applications of alkoxysilane-containing paint materials and the importance of siloxanes in the develop¬ ment of novel coating systems are limited.

Siloxanes are therefore still being sought which can be used for the incorporation of a post application cross-linking mechanism in aqueous coating compositions, in which the siloxane latex obtained either shows no premature cross-linking or else an acceptable degree of premature cross-linking.

It was found, however, that it is not possible to suppress the premature cross-linking of the alkoxysilanes without detracting from the post-application cross- linking during the film formation and the properties of the coating obtained.

The article by Bourne et al. , Journal of Coatings Technology, Vol 54, No. 684, pp.69-82 (1982) discloses that, even though the premature cross-linking of alkoxy¬ silyl latices depends strongly on the conditions employed, such as the pH, the premature cross-linking of alkoxysilyl latices can be suppressed by using sterically hindered alkoxysilanes, for example by using methacryl- oxypropyltriisopropoxysilane instead of methacryloxy- propyltrimethoxysilane.

The studies by Bourne et al. have also shown, however, that methacryloxypropylmethyldiethoxysilane gives less premature cross-linking than methacryloxy- propyltriisopropoxysilane, even though in the latter compound the silicon atom carries sterically larger alkoxy substituents.

On the basis of their study, Bourne et al. arrive at the following sequential order for the hydrolysis resis- tance of siloxanes: trimethoxy, methyldimethoxy < triethoxy, tri- isopropoxy << methyldiethoxy, without, however, giving an explanation for the fact that the methyldiethoxysilane compound gives less premature cross-linking than the sterically more strongly hindered triethoxy- or triisopropoxysilanes.

Moreover, Bourne et al. report that the premature cross-linking of their best compound, methacryloxypropyl- methyldiethoxysilane, is still too high for general use in advanced aqueous coating compositions, so that the use of these siloxanes is restricted to possible applications in which pre-crosslinked latices are used. It is therefore an object of the invention to provide siloxanes having a lower hydrolysis rate than the alkoxysilanes from the prior art.

A further object of the invention is to provide siloxanes which result in a lower degree of premature cross-linking than the alkoxysilanes from the prior art.

Yet another object of the invention is to provide siloxane latices which show a lower degree of premature cross-linking during the emulsion polymerization and/or. during storage than latices which are composed on the basis of the known alkoxysilanes.

These objectives are achieved according to the invention by the use of siloxanes, in which at least one group is bound directly, via a carbon atom, to the silicon atom and of which at least one of the silyloxy groups has an electronegative character.

Owing to the presence of these electronegative silyloxy groups, the siloxanes of the invention have a much lower hydrolysis rate than the alkoxysilanes from the prior art, in particular the best compound from the systematic study by Bourne et al, viz. methacryloxy- propylmethyldiethoxysilane.

Furthermore, latices which contain the siloxanes of the invention, show less premature cross-linking than latices which contain the alkoxysilanes from the prior art.

The higher stability of the alkoxysilane monomers of the invention is found, however, after emulsion copolymerization of the siloxanes with ethyl acrylate or n-butylmethacrylate into a latex, not significantly to hinder post-application cross-linking during film forma¬ tion.

The invention therefore relates to siloxanes having the formula 0 R,

II I ²

R_x - C - 0 - X - Si - 0R₃ (I)

0R₄ wherein

R-_L is an optionally substituted alkenic group having 2-10 carbon atoms,

X is an alkylene having 1-20 carbon atoms which may or may not be substituted and/or optionally comprises one or more heteroatoms, alkenic bonds, alkynic bonds, cyclic groups and/or aromatic groups,

R₂ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substi¬ tuted aromatic group, an optionally substituted hetero- aromatic group or an optionally substituted silylalkyl group,

R₃ and R₄ each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted hetero- aromatic group, or wherein the R₃ and R₄ groups, together with the oxygen atoms to which they are bound and the silicon atom, form an optionally substituted ring structure, or wherein one of the groups R₃ or R₄, together with the oxygen atom to which it is bound, the silicon atom and the R₂ group, forms an optionally substituted ring structure, at least one of the groups R₃ or R₄ having a greater electronegativity than the methyl group.

In the compounds having formula I, preferably both groups R₃ and R₄ have a greater electronegativity than the methyl group.

The invention further relates to formula II 0 R₂

II I ²

R_x - C - 0 - X - Si - 0R₃ ( II )

wherein R_x and X have the meanings given above, and

R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substi¬ tuted aromatic group, an optionally substituted hetero- aromatic group or an optionally substituted silylalkyl group, or wherein R₂ and R₂', together with the silicon atom to which they are bound, form an optionally substi- tuted ring structure,

R₃ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ group, together with the oxygen atom to which it is bound, the silicon atom and one of the groups R₂ and R₂' , forms an optionally substituted ring struc¬ ture, the group R₃ having a greater electronegativity than the methyl group.

The invention further relates to the use of the siloxanes of the formulae I and II in the preparation of coating compositions and to coating compositions which contain one or more siloxanes of the formulae I and II as described hereinabove.

The invention finally relates to the use of said coating compositions in the coating of a substrate or product and to a substrate or product which has been coated with one or more of said coating compositions. In the compounds of formula I and II, the groups R₃ and/or R₄, and in the case of the compounds of formula I preferably both, have a greater electronegativity than the methyl group, i.e. they are groups having an elec- tron-withdrawing character.

Said electronegative and/or electron-withdrawing character can be obtained by means of the type of the group and/or the presence of electronegative atoms in the group and such electronegative groups are generally known to those skilled in the art. Examples are, inter alia, the carbonyl group (CO-R), alkenic groups or alkynic groups.

Further, the groups R₃ and R₄, and in the case of compounds of formula I preferably both, may contain one or more electronegative substituents, as a result of which the groups R₃ and R₄ are provided with an electronegative character or as a result of which the electronegative character of the R₃ and R₄ groups is enhanced. Thus the R₃ and R₄ groups can be alkyl groups which contain electronegative substituents.

Said electron-withdrawing substituents are preferably groups which have an inductive effect (-1 effect) on the hydrolysis of the silyl ether bond. This generally refers to electronegative groups which, owing to, for example, electrostatic or dipole effects, favour the formation of a negative charge during or after the reaction (i.e. in a transition state or in a reaction product).

Such electron-withdrawing groups having an inductive effect (-1 effect) are generally known in the literature. Thus a number of these groups and an explanation of their effect is described in E.S. Gould "Mechanism and struc¬ ture in Organic Chemistry", Holt, Rinehart and Winston, New York, 1959, pp. 200-209, the content of which is to be regarded as incorporated herein. The invention is, however, not limited, to the groups or mechanisms mentioned in said reference. The electron-withdrawing groups having a -I effect are generally groups having a o_x value or an F value greater than zero.

These values are described in J. March, Advanced Organic Chemistry, 3rd Ed., John Wiley and Sons, 1983, pp. 245-247, where a number of groups having a -I effect are also mentioned. The content of this literature reference and the references mentioned there should be regarded as incorporated herein. The inductive effect of these substituents decreases, as the electronegative substituent in the carbon chain is further removed from the silyl ether bond. Thus the effect of a substituent on a γ carbon atom is smaller than the effect of a substituent on a β carbon atom. The electronegative substituents are therefore preferably bound, in the compounds of the formulae I and II, to the α or β carbon atom, and preferably the α carbon atom of the R₃ or R₄ group.

In the compounds having formula I and II, the one or more electronegative substituents are preferably chosen from the series comprising CF₃, CC1₃, CN, nitro, halogen, -0-C0-R₅, -C0-0R₅, -(C=0)-R₅, -CR₅=CR₅R₆ and -NR₅R₆, in which R₅ and R₆, independently, is H or an optionally substituted alkyl group, alkenic group, alkynic group or aromatic group.

The electron-withdrawing substituents are more preferably chosen from the group comprising CF₃, CC1₃, CN, N0₂ and halogen and are most preferably -CF₃ and/or -CC1₃. Further, in the compounds of the formulae I and II: - the R_λ group is preferably an optionally substituted ethene group, preferably an ethene group or a 1-methyl- ethene group and most preferably a 1-methylethene group, the linking group X preferably is an optionally substituted alkyl group having 1-6 carbon atoms, prefer- ably an optionally substituted alkyl group having 3-4 carbon atoms and more preferably an n-propyl group, the R₂ and R₂' groups are preferably, independently, a branched or straight-chain or cyclic alkyl group having 1-6 carbon atoms or a substituted phenyl group, and preferably are a methyl, ethyl, propyl, isopropyl, t- butyl or phenyl group. According to a specific preferred embodiment, the groups R₂ and R₂' are a substituted silylalkyl group having 10 carbon atoms in the alkyl groups, such as, for example, a tris(trimethylsilyl)- methy1 group (C(SiMe₃)₃). The compounds whose use is most preferred are (meth)acryloxypropyl(di- or mono)alkyl (mono- or di)- siloxanes, in which the alkoxy groups carry one or more electronegative substituents, and in particular compounds such as (meth)acryloxypropylmethylbis(2,2,2-trifluoro- ethoxy)silane, (meth)acryloxypropylmethylbis(2,2,2- trichloroethoxy)silane, (meth)acryloxypropyldimethyl- (2,2,2-trifluoroethoxy)silaneand (meth)acryloxypropyldi¬ methyl(2,2,2-trichloroethoxy)silane.

If in this application a group is optionally substi- tuted, the optional substituents are chosen independently from, inter alia, branched and straight-chain alkyl having 1-10 carbon atoms, branched and straight-chain alkenic groups having 1-10 carbon atoms, branched and straight-chain alkynic groups having 1-10 carbon atoms, aryl groups having 1-10 carbon atoms, hydroxyl, nitro, amino, amine groups, halogen (Cl, Br, F and I), sulphate, sulphone, sulphydryl, cyano, carboxyl, carbonyl, ether, ester and heteroaromatic groups and the like. These substituents may occur in the groups R₃ and R₄ in addition to the electronegative substituents.

The siloxanes of formula I show a lower hydrolysis rate than the siloxanes from the prior art.

Thus the experiments described hereinafter have shown that one of said compounds of the invention, methacryloxypropylmethylbis(2,2,2-trifluoroethoxy)silane, shows a hydrolysis rate which at 80^βC is eight times lower than the best compound of Bourne et al., methacryl- oxypropylmethyldiethoxysilane. Also, it has been shown that said monomer as an aqueous emulsion at 20^βC, is hydrolysed 60 times slower than the best compound of Bourne et al. and 70 times slower than methacryloxypro- pyltrimethoxysilane.

It was further found that alkoxysilyl latices which are composed using the siloxanes of the invention show less premature cross-linking than the alkoxysilyl latices from the prior art, without this being detrimental to cross-linking during film formation.

It is assumed that this decrease in the premature cross-linking is generally due to the lower hydrolysis rate of the siloxanes. The invention is not restricted to this explanation, however. Thus it is possible that the siloxanes of the invention are indeed (partially) hydrolysed during storage, but that the silanol monomers obtained in the process do not cross-link directly, so that a stable latex is obtained which subsequently, after application of the composition and possibly after catalysis or a different type of activation, is cross-linked rapidly.

It is further possible, as disclosed by Bourne et al., for the premature cross-linking of alkoxysilyl latices to be reduced yet further by the use of steri- cally hindered siloxanes, which is also true for the siloxanes of the invention, whose alkoxy groups carry one or more electronegative substituents.

The siloxanes of formula I and II, in which one or more of the groups R₂ and R₂', R₃ and R₄, and in particular the alkyl groups R₂ and R₂', provide steric hindrance, therefore form an important aspect of the invention.

The term steric hindrance, together with the groups which can provide steric hindrance, are generally known in the art. Such groups are generally strongly branched, such as, for example, the isopropyl and isopropoxy groups, which are described in the paper by Bourne et al. , whose content is to be regarded as incorporated herein. The invention is not, however, restricted, to the groups described by Bourne et al.

The further decrease of the premature cross-linking which is obtained by the use of sterically hindered siloxanes of formula I and II will in general be a result of a further decrease in the hydrolysis rate, which is obtained by the steric hindrance in the siloxanes. It is not the only possible explanation, however.

Thus the study by Bourne et al. has shown that methacryloxypropylmethyldiethoxysilane gives less pre¬ mature cross-linking than methacryloxypropyltriisopro- poxysilane, which shows that greater steric hindrance does not necessarily lead to a decrease in premature cross-linking. It was further possible, in the siloxanes of the invention, that a compound according to formula I or II, in which R₂ and/or R₂' is an alkyl group or silylalkyl group providing steric hindrance, and the alkoxy group -0R₃ carries one or more electronegative substituents, (partially) hydrolyses during storage but, owing to the steric hindrance, barely gives rise to premature cross- linking/gelling.

It is also possible that, owing to the simultaneous presence of the groups providing steric hindrance and of the electronegative substituents in the siloxanes, synergistic effects are obtained, for example by the electronegative substituents contributing to the steric hindrance or vice versa.

It is further possible that synergistic effects are obtained owing to the reactivity being lowered as a result of the presence of R₂ or R₂' , which leads to prevention or reduction of possible conjugation, such as is possible in a compound of the type R₁-X-Si(0R)₃.

Yet another possibly occurring mechanism is that a compound having larger ("more bulky") groups on R₂ or R₂' can prevent conjugation of electrons with the silicon atom, as a result of which the hydrolysis reaction and cross-linking are slower.

It is also conceivable for both the presence of electronegative groups on R₃ and/or R₄ and the presence of bulky groups on R₂ and/or R₂' together to have an effect on the prevention of premature gelling, synergism being obtainable in this case.

The invention is therefore not restricted to a specific mechanism as an explanation for the fact that the siloxanes of the invention give a decrease in pre- mature cross-linking in alkoxysilyl latices.

It is more a matter of the hydrolysis of the siloxanes, the premature cross-linking of the alkoxysilyl latices and the ultimate post-application cross-linking during film formation being affected by various mutually dependent factors.

Thus, the premature cross-linking and the post- application cross-linking of the coating compositions of the invention also depend on the pH, the emulsifiers used, the presence of catalysts or a combination thereof and the temperature. Cross-linking and post-application cross-linking can be accelerated, for example, by raising or lowering the pH (pH jump by means of a volatile component and/or a volatile pH-buffer) or a different type of catalysis, for instance the use of silica, a silicate or another filler or pigment, a metal salt, such as a metal halogenide, or an organometallic compound. Preferably catalysis is carried out by means of a combi¬ nation of any of such methods.

The invention does make it possible, however, to obtain, by the correct choice of the alkyl and alkoxy groups and electronegative substituents in the siloxanes, together with the further constituents and reaction conditions in the alkoxysilyl latices, a good equilibrium between an acceptable premature cross-linking during the polymerization and during storage in the pot on the one hand, and adequate post-application cross-linking capa¬ city after application of the paint and during film formation on the other hand.

As stated previously, the alkoxysilyl latices described in the literature undergo premature hydrolysis during the emulsion polymerization and during storage in the pot. According to Bourne et al. , this hydrolysis sensitivity can be reduced by sterically hindering groups being bound to the silicon atom, although it was not found to be possible to effectively suppress the hydro¬ lysis reaction without losing the post-application cross- linking activities.

According to the invention use is also made, possibly in addition to or in combination with the effect of steric hindrance, of inductive effects in order to find a good equilibrium between, on the one hand, an ac- ceptable stability against hydrolysis during the polymerization and storage and, on the other hand, sufficient post-application cross-linking activity after applying the paint.

As the experiments below show, siloxanes having electronegative groups, such as groups carrying electron- withdrawing substituents having an inductive character, give a much lower hydrolysis rate in water than the most hydrolysis-resistant compound from the literature (Bourne et al.). The increase in stability is found, after copolymerization with ethyl acrylate or n-butyl- methacrylate, not to restrict significantly the post- application cross-linking during drying.

In addition to the premature cross-linking, the latices of Bourne et al. also presented problems in terms of colloidal stability and, particularly, of coagulation of the latex particles.

These problems can be overcome, according to the invention, by incorporating in the siloxanes of the invention one or more surface-active groups. According to one aspect of the invention, at least one of the groups R₂, R₂', R₃ and R₄ of the siloxanes of formula I or formula II contain one or more surface- active groups.

The term surface-active groups generally refers to groups which provide the hydrophobic alkyl and alkoxy groups in the siloxanes of formula I and II with hydrophilic properties, and such groups will be evident to those skilled in the art.

Said surface-active groups are generally chosen from anionic groups such as carboxylate, sulphate, sulphonate, phosphate and the like; cationic groups such as imidazo- line, amine or quaternary ammonium, ampholytic groups such as sulphoalkylimidazolium and sulphoalkylpyridinium salts, sulphoalkylammonium salt, sulphoalkyl- and alkyl- carboxybetaine, piperidinium and pyridinium alkyl carboxybetaine, and the like, and non-ionic groups such as polyethylene glycols, such as alkylphenol polyglycol ethers, alkylpolyglycol ethers, fatty acid polyglycol ethers or copolymers of polyethylene glycol and polypropylene glycol, and alkylolamides.

Said surface-active groups may possibly also have an inductive effect on the hydrolysis of the silylether bond, contribute to steric hindrance or in some other way diminish premature cross-linking of the alkoxysilyl latices in which they have been incorporated.

The coagulation of the latex particles may further also be diminished by copolymerization with 0.01-20 %, preferably 0.1-10 % of (meth)acryliσ acid, based on the monomeric constituents of the polymeric binder.

Instead of using surface-active groups on the siloxan itself according to the invention it is also possible to use a suitable surfactant or combination of surfactants, as will be clear to a man skilled in the art.

The siloxanes of formula I and II can be prepared in any way known per se, and in particular by reaction of an alkyldihalosilane having formula III, in which Hal represents a halogen atom, with an equivalent or a slight excess of an appropriately substituted alkanol, according to:

R

I 2

R. - X - Si - Hal + 2H0-R₃

I

Hal

R₂

R_x - X - Si - OR₃ + 2 Hal 0R₃ in the presence of approximately 1 equivalent or a slight excess of an organic base such as triethylamine or pyridine.

This reaction is generally carried out in an inert organic solvent at a temperature of from approximately room temperature to the boiling point of the solvent used. The reaction mixture is stirred for from some minutes to several hours, after which the siloxanes can be isolated in a known manner, for example by distillation.

The siloxanes of formula I and II can also be prepared by a reaction of the silyl ether with a suitably substituted alkanol, the ether group being replaced by the alkanol group, according to, for example

^R2

This transetherification reaction is described, inter alia, by A.F. Reilly and H.W. Post, J. Org. Chem., 16, p. 383 (1951), the content of which is to be regarded as incorporated herein.

The invention further relates to the use of the siloxanes according to formula I, wherein R_x is an optionally substituted alkenic group having 2-10 carbon atoms,

R₂ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substi¬ tuted aromatic group, an optionally substituted hetero¬ aromatic group or an optionally substituted silylalkyl group, R₃ and R₄ each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ and R₄ groups, together with the oxygen atoms to which they are bound and the silicon atom, form an optionally substituted ring structure, or wherein one of the groups R₃ or R₄, together with the oxygen atom to which it is bound, the silicon atom and the R₂ group, forms an optionally substituted ring structure, at least one of the groups R₃ or R₄ having a greater electronegativity than the methyl group, or of formula II, wherein

R-_L and X have the meanings given above, and R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substituted aromatic group, an optionally substituted heteroaromatic group or an op- tionally substituted silylalkyl group, or wherein R₂ and R₂' , together with the silicon atom to which they are bound, form an optionally substituted ring structure, R₃ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ group, together with the oxygen atom to which it is bound, the silicon atom and one of the groups R₂ and R₂' , forms an optionally substituted ring struc¬ ture, the group R₃ having a greater electronegativity than the methyl group, in the preparation of coating compositions.

The invention further relates to coating composi¬ tions obtainable by said use/method.

The siloxanes according to the invention will, in this context, generally be used in the same or an analo¬ gous manner and in the same quantities as the siloxanes known from the prior art.

The lower hydrolysis rate and the reduced premature cross-linking do make it possible, however, for the siloxanes of the invention to be used in coating compo¬ sitions for which the known siloxanes, because of their excessive hydrolysis rate and/or the excessive premature cross-linking, are not suitable. As a result, the field of application of the post-application cross-linking mechanisms on the basis of siloxanes is further extended.

Yet another aspect of the invention relates to coating compositions which contain one or more siloxanes according to formula I, wherein

R is an optionally substituted alkenic group having 2-10 carbon atoms,

R₃ and R₄ each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ and R₄ groups, together with the oxygen atoms to which they are bound and the silicon atom, form an optionally substituted ring structure, or wherein one of the groups R₃ or R₄, together with the oxygen atom to which it is bound, the silicon atom and the R₂ group, forms an optionally substituted ring structure, at least one of the groups R₃ or R₄ having a greater electronegativity than the methyl group, or of formula II, wherein Rj and X have the meanings given above, and

R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substituted aromatic group, an optionally substituted heteroaromatic group or an op¬ tionally substituted silylalkyl group, or wherein R₂ and R₂' , together with the silicon atom to which they are bound, form an optionally substituted ring structure, R₃ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ group, together with the oxygen atom to which it is bound, the silicon atom and one of the groups R₂ and R₂' , forms an optionally substituted ring struc¬ ture, the group R₃ having a greater electronegativity than the methyl group.

With "containing" it is meant that the siloxanes of the invention are added to the coating composition during the preparation thereof, and that they are present in the composition as such or for instance build into / incor¬ porated in the polymerized latex in order to provide the cross-linking activity to said polymers, as will be clear to a mann skilled in the art. The coating compositions preferably comprise a one- pack water-based dispersion paint and most preferably an acrylic paint.

These compositions of the invention can further contain any other constituents known per se, such as organic and inorganic pigments, dyes, fillers, e ulsi- fiers, thickeners and other additives, and these sub¬ stances will be generally known to those skilled in the art.

Examples of inorganic pigments are, inter alia, titanium dioxide and red iron oxide, of organic pigments phthalocyanine blue and green, while fillers to be mentioned include, inter alia, chalk and talc, and thickeners include cellulose derivatives, acrylic thickeners, inorganic rheological additives, such as silica, bentonite and other silicates, and associative thickeners. According to one embodiment of the invention, the emulsifier used is a combination of an anionic, a custo¬ mary non-ionic and a siloxane-containing non-ionic emulsifier. By means of this combination of emulsifiers, alkoxysilyl latices having a solids content of 40 % by weight can be prepared, only a small amount of coagulum being formed. The combination of emulsifiers which is used in the examples gives particularly favourable results and makes it possible to achieve high solids contents in the coating compositions. The binder, water and the other constituents will generally be present in the composition in the customary amounts.

The siloxanes of the invention are generally present in the coating composition in an amount of from 0.001-25 mol% and preferably an amount of 0.1-5 mol%, based on the polymeric binder.

It is, however, also possible for the siloxanes of the invention to be used as the binder by themselves, a water-repellent coating being obtainable in the process, for example. In this case, the siloxanes can also be combined with other binders. Further possible fields of application of the siloxanes of the invention are, inter alia, the use in printing inks and in adhesives and glues. The siloxanes of the invention can further be used in coatings as means for improving the adhesion with respect to both the substrate and pigment or filler particles. The latter is also important for plastics / polymeric materials (for example a major increase in tensile strength, flexibility and impact strength are then possible).

The preparation of the coating compositions of the invention can be carried out in any manner known per se, the siloxanes of the invention being used in the same or in an analogous manner as the siloxanes from the prior art.

In so doing, when the siloxanes of the invention are employed, the hydrolysis of the siloxanes and the cross- linking during the emulsion polymerization, the storage and further processing of the coating composition are reduced. It is further important that the pH during the emulsion polymerization is kept at 6.0-8.0, because otherwise large amounts of coagulate are obtained.

The preparation of the coating compositions can be carried out, for example, in a similar manner to the preparation of customary acrylic paints. In the process, the following constituents are made into a ground paste: demineralized water, a dispersant, optionally another surfactant, optionally a wetting additive, optionally a thickener, an anti-foaming agent, biocide, pigment, fillers. After dispersion of this ground paste to a fineness of grind of approximately 5-20 micrometres, the siloxane-modified latex, a thickener and optionally an anti-foaming agent are then added with a moderate mixing rate, after which the pH of the composition is optionally brought to pH 6.0-8.0.

Yet another aspect of the invention relates to the use of the above-described coating composition in coating a substrate or product and to a coated substrate or product which is coated with one or more of the above- described coating compositions.

The coating can be carried out in any manner known per se, such as brushing, rolling, spraying, immersion and the like.

The products and substrates comprise all customary substrates and products which are generally coated with the coating compositions employed.

The invention will be described below in more detail with reference to the following examples and figures which do not restrict the field of the invention.

In Example 1, the preparation of one of the siloxanes of the invention, methacryloxypropylmethyl- bis(2,2,2-trifluoroethoxy)silane, is described in more detail. In Examples 2 and 3, the hydrolytic stability of a compound according to the invention is compared, by means of analysis using of a gas chromatograph, with the hydrolytic stability of two alkoxysilanes from the prior art, at higher temperatures up to about 80°C and at ambient temperature (20°C), respectively.

In Examples 4-10, the preparation of the latices according to the invention and the prior art, which are studied in Examples 11 and 12, is explained in more detail. In Examples 11 and 12 the curing of a polyethyl- acrylate latex and a poly-n-BMA-latex respectively, using an alkoxysilane of the invention as a comonomer are compared with the curing of latices by means of post- application cross-linking mechanisms on the basis of siloxanes from the prior art.

This is done by considering the K5nig hardness (NEN 5319) and the solvent resistance as determined by the number of MEK rubs. The combination of these two properties provides a good measure for the cross-linking after application of the paint.

Finally, in Example 8, the preparation of a coating composition of the invention is explained in more detail. Figure I depicts the setup employed in Example 2, where the symbols have the following meanings: 1: reactor 2: pump 3: gas chromatograph 4: integrator

5: Dosimat type: Metrohm 665

6: pH-stat

TC: temperature controller on top of the reactor TI: temperature indicator for all thermocouples employed

UC: transformer for controlling supply and discharge temperature

XC: speed control for the pump.

Example 1 Preparation of methacryloxypropylmethylbis(2,2,2-tri- fluoroethoxy)silane.

0.44 mol of trifluoroethanol was added dropwise to a solution of CH₂=C(CH₃)COO(CH₂)₃Si(CH₃)Cl₂ (0.2 mol) and triethylamine (0.44 mol) in 700 ml of toluene dried on 4 Angstrom molecular sieves.

After stirring at room temperature for 23 hours, the reaction mixture was filtered. The filtrate was distilled at reduced pressure and the desired product, CH₂=C(CH₃)COO(CH₂)₃Si(CH₃)(OCH₂CH₃)₂, was obtained in a yield of virtually 100 % (boiling point 84°C/0.5 mm Hg), ^-N R (CDC1₃) δ 0.22 (s, CH₃), 0.72 (m, SiCH₂), 1.73 (m, CH₂), 1.90 (s, CH₃), 3.99 (t, SiCH₂CF₃), 4.08 (m, 0CH₂), 5.51 and 6.06 (bs, 2H_vinyl) ppm.

Example 2 Determination of the hydrolysis rate at higher tempera¬ tures (up to 85°C).

In this example, the hydrolysis rate at higher temperatures (up to 85^βC) of one of the siloxanes of the invention, methacryloxypropylmethylbis(2,2,2-trifluoro- ethoxy)silane, was compared with the hydrolysis rate of two siloxanes from the prior art, namely methacryloxypro- pyltrimethoxysilane and methacryloxypropylmethyldi- ethoxysilane, the best compound from the study by Bourne et al. The hydrolysis rates were determined at pH7 on the basis of the decrease in concentration of the monomeric siloxane starting material, which was monitored by on¬ line head space GC analysis. The setup shown in Figure 1 was used for this purpose. In these experiments, the alkoxysilyl monomer was added to the water in a low concentration, so that the water concentration during the experiment could be assumed to be constant.

Consequently, the variation with time of the concen- tration of the siloxane monomer can be described as a pseudo first-order reaction, so that the hydrolysis rate constant of the siloxane monomer k_hydr was determined as follows from the decrease in the concentration of this siloxane monomer: In [C⁸] = In [C₀ ^β] - k_hydr- [H₂0] -t where C^β] = concentration of siloxane in mol/1

[C₀ ^S] = initial concentration of siloxane in mol/1 ^k _hydr = hydrolysis rate constant in l/mol«s [H₂0] = concentration of water in mol/1 t = time in seconds. The silanol compounds, i.e. the hydrolysed monomers, have a much lower evaporation rate, due to hydrogen bonds being formed, as a result of which they evaporate hardly at all and are barely detected.

The results are shown in Table 1, the temperature at which the determination was carried out being reported in parentheses.

Table 1 Hydrolysis rate constant of the siloxane monomers

Alkoxysilane 1, siloxane ^Λhydr ,

[litre s^"1 mol^"1]

Methacryloxypropy1tri- methoxysilane (47°C) 4.1 • 10"⁵

Methacryloxypropyltri- methoxysilane 6.1 • 10-⁵

(62°C)

Methacryloxypropylmethyldi- ethoxysi1ane 2.4 • 10^"5

(62°C)

Methacryloxypropylmethyldi- ethoxysi1ane 8.0 • 10"⁵

(81°C)

Methacryloxypropylmethylbis- (2,2,2-trifluoroethoxy)silane 1.0 • 10"⁵ (invention) (85°C)

The results show that the methacryloxypropylmethy1- bis(2,2,2-trifluoroethoxy)silane according to the inven¬ tion has a hydrolysis rate, at 85°C, which was 8.0 times lower than the hydrolysis rate of the best compound of Bourne etal., methacryloxypropyImethyldiethoxysilane, at a comparable temperature.

It is found, moreover, that the hydrolysis rate of the alkoxysilane of the invention is much lower than the hydrolysis rate of methacryloxytrimethoxysilane at a much lower temperature (47.1°C).

The results of this experiment in any case show that it is possible, by introducing one or more electron- withdrawing substituents having a (-1) effect in the alkoxy groups, for the hydrolysis rate of siloxanes to be reduced.

Example 3 Determination of the hydrolysis rate at ambient tempera¬ ture.

In this example, the hydrolysis rate at ambient temperature (20°C) of one of the siloxanes of the inven¬ tion, methacryloxypropylmethylbis-(2,2,2-trifluoro¬ ethoxy)silane, was compared with the hydrolysis rate of two siloxanes from the prior art, viz. methacryloxypro- pyltrimethoxysilaneandmethacryloxypropylmethyldiethoxy- silane, the best compound from the study by Bourne et al. The hydrolysis rates were determined at pH 7 in emulsions of the pure silane monomer in an aqueous continuous phase in the presence of a surfactant (sodium- dodecylbenzene sulfonate).

In these experiments, the monomer concentration was 4,6 g/1 water and the amount of surfactant was 24-40 wt.% based on the monomer. As a function of the hydrolysis time, samples were taken with a microsyringe (1 μl) and injected into a gas chromatograph with a flame ionization detector (Carlo Erba G 6000 determining vega). The hydrolysis reaction was followed by means of the decrease of the silane monomer or the increase of the formed alcohol, as well as the calculation of the rate constant of the hydrolysis, carried out as described in example 2. The results are shown in Table 2.

Table 2 Hydrolysis rates constants of the siloxane monomers at

20°C in aqueous emulsion

20°C, pH=7 % ιo⁸* _d Average Monomer Emulsifier (l.mo ¹)

(l.m^kol^h-^yl^ds^a- 1

TMS 24 232 2.6^*10^"6 216 251 342

MDES 28 202 2.0*10^"6 181 223 181

F 40 3.5 3.5*10^"8 2.8 4.2 TMS: methacryloxypropyltrimethoxysilane MDES: methacryloxypropylmethyldiethoxysilane F: methacryloxypropylmethyldi( 2,2, 2-trifluoro¬ ethoxy)silane

The results show that the methacryloxypropylmethyl- bis-(2,2,2-trifluoroethoxy)silane according to the invention is hydrolyzed very much slower at 20°C than the best compound of Bourne et al., methacryloxypropylmethyl- diethoxysilane, i.e. about 60 times as slow in the above emulsions. Compared with methacryloxypropyltrimethoxy- silane the hydrolysis of the monomer of the invention at this temperature is about 70 times as slow. These results confirm that by introducing one or more electron with¬ drawing substituents with a -(I)- effect in the alkoxy groups, the rate of hydrolysis of the alkoxysilanes can be reduced substantially.

Example 4

Preparation of latex 1 (ethyl acrylate, reference)

The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condenser, nitrogen inlet, temperature controller and a pH-stat which maintains the pH at 7 by automatic titration with an aqueous 0,2 M NaOH-solution. Weighed into the polymerization reactor were 158.83 g of distilled water, 100.05 g of ethyl acrylate, 2.91 g of sodium dodecyl sulphate, 1.55 g of Triton X100 (Union Carbide, a non-ionic emulsifier prepared from an octyl- phenol with ethylene oxide), 0.45 g of Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicone basis) and 1.11 g of lauryl mercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which it is added with 0.91 g of ammonium persulphate. The pH of the emulsion is then set to 7. The emulsion is now brought to 50^CC. After the temperature jump to about 80°C as a result of initiation, the temperature is maintained at 70°C for about 4.5 hours. Solids content 40.2 %.

The latices 2 to 10 inclusive were prepared in an analogous manner. There are no significant differences in the manner of preparation. The only difference is the type of comonomers, apart from small variations in the amounts of the other components (emulsifiers, initiators), the reaction time, and in some cases a phos¬ phate buffer was used instead of titration with NaOH using a pH-stat.

Example 5

Preparation of latex 2 (n-butylmethacrylate, reference).

The reaction is carried out in a 1 liter polymerization reactor, provided with a stirrer, reflux condensor, nitrogen inlet, and temperature controller. In the polymerization reactor, 289 g distilled water, 1.52 g NaH₂P0₄ and 1,09 g Na₂HP0₄ (phosphate buffer), 198.3 g n- butylmethacrylate, 5.60 g sodium dodecyl sulfate, 3.2 g Triton X 100 (Union Carbide, a non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.80 g Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicon basis) and 1.95 g laurylmercaptan as a chain transfer agent. To remove oxygen this emulsion is purged with nitrogen for 30 minutes, after which 0.73 g ammonium persulfate is added. The pH of the emulsion is then 6.5. The emulsion is now brought to 50°C. After the tempera¬ ture jump to 81°C as a result of initiation, the tempera¬ ture is maintained at about 60°C during about 0.5 hour. Total reaction time: 1 hour, total solids content: 41.6 %. The pH is 6.5.

Example 6

Preparation of latex 3 (methacryloxypropyltrimethoxy- silane/ethylacrylate , prior art)

The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condenser, nitrogen inlet, temperature controller and a pH-stat which maintains the pH at 7 by automatic titration with an aqueous 0.2 M NaOH-solution. Weighed into the polymerization reactor were 154.12 g of distilled water, 89.98 g of ethyl acrylate, 9.04 g of methacryloxypropyltrimethoxysilane, 2.86 g of sodium dodecyl sulphate, 1.23 g of Triton X100 (Union Carbide, a non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.77 g of Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicone basis) and 0.90 g of lauryl mercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which 0.89 g of ammonium persulphate is added. The pH of the emulsion is then set to pH7. The emulsion is now brought to 50°C. After the temperature jump to 80°C as a result of initiation, the temperature is maintained at 70°C for 4.5 hours. Solids content 40.7 %.

Example 7

Preparation of latex 4 (methacryloxypropylmethyldiethoxy- silane/ethylacrylate, prior art)

The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condenser, nitrogen inlet, temperature controller and a pH-stat which maintains the pH at 7 by automatic titration with an aqueous 0.2 M NaOH-solution. Weighed into the polymerization reactor were 153.60 g of distilled water, 99.94 g of ethyl acrylate, 9.30 g of methacryloxypropylmethyldiethoxysilane, 2.97 g of sodium dodecyl sulphate, 1.50 g of Triton X100 (Union Carbide, a non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.49 g of Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicone basis) and 1.10 g of lauryl mercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which 0.89 g of ammonium persulphate is added. The pH of the emulsion is then set to pH7. The emulsion is now brought to 50°C. After the temperature jump up to about 80°C as a result of initiation, the temperature is maintained at 70°C for 4.5 hours. Solids content 43.0 %.

Example 8

Preparation of latex 5 (methacryloxypropylmethyldiethoxy- silane/n-butylmethacrylate).

The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condensor, nitrogen inlet, and temperature controller. Weighed into the polymerization reactor were 154.54 g distilled water, 89 g n-butylmethacrylate, 9.79 g meth¬ acryloxypropylmethyldiethoxysilane, 2.8 g sodium dodecyl- sulfate, 1.62 g Triton X 100 (Union Carbide, non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.41 g Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicone basis) and 0.93 g lauryl- mercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which 0.45 g ammonium persulfate is added. The pH of said emulsion is then 6.5. The emulsion is now brought to 50°C. After the temperature jump to 63^βC as a result of initiation, the temperature is maintained at 50°C during 1 hour. Total reaction time: 1.5 hours, solids content: 38.8 %. The pH is 6.5.

Example 9

Preparation of latex 6 (methacryloxypropylmethylbis- (2,2,2-trifluoroethoxy)silane/ethylacrylate, invention) The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condenser, nitrogen inlet, temperature controller and a pH-stat which maintains the pH at 7 by automatic titration with an aqueous 0.2 M NaOH-solution. Weighed into the polymerization reactor were 145.15 g of distilled water, 91.35 g of ethyl acrylate, 9.07 g of methacryloxypropylmethylbis(2,2,2-trifluoroethoxy)silane, 2.85 g of sodium dodecyl sulphate, 1.63 g of Triton X 100 (Union Carbide, a non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.43 g of Silwet L 2607 (Union Carbide, non-ionic emulsifier on a silicone basis) and 0.98 g of lauryl mercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which 0.88 g of ammonium persul¬ phate is added. The pH of the emulsion is then set to pH7. The emulsion is now brought to 50°C. After the temperature jump to about 80^βC as a result of initiation, the temperature is maintained at 70°C for 4.5 hours. Solids content 42.5 %.

Example 10 Preparation of latex 7 (methacryloxypropylmethylbis- (2,2, 2-trifluoroethoxy)silane/n-butylmethacrylate, invention)

The reaction is carried out in a 0.5 1 polymerization reactor, provided with a stirrer, reflux condensor, nitrogen inlet, and temperature controller. Weighed into the polymerization reactor were 144.9 g distilled water, 0.54 g Na₂HP0₄ and 0.76 g NaH₂P0₄ (phos¬ phate buffer), 87.75 g n-butylmethacrylate, 9.31 g methacryloxypropylmethylbis-(2,2,2-trifluoroethoxy)- silane, 2.82 g sodium dodecyl sulfate, 1.61 g Triton X 100 (Union Carbide, non-ionic emulsifier prepared from an octylphenol with ethylene oxide), 0.4 g Silwet L 2607 (Union Carbide, non-ionic emulsifier on silicone basis) and 0.98 g laurylmercaptan as a chain transfer agent. To remove oxygen, this emulsion is purged with nitrogen for 30 minutes, after which 0.44 g ammonium persulfate is added. The pH of the emulsion is then 6.5. The emulsion is now brought to 50°C. After the temperature jump to about 65°C as a result of initiation, the temperature is maintained at about 55°C during 1 hour. Total reaction time: 1.5 hours, solids content: 39.7 %, the pH is then 6.3.

Example 11

Determination of the post-application cross-linking in ethylacrylate/alkoxysilyl latices.

In order to determine the effect of the presence of electronegative substituents in the siloxanes on the post-application cross-linking of a latex, one of the siloxanes of formula I and II, methacryloxypropylmethyl- bis(2,2,2-trifluoroethoxy)silane, and two siloxanes from the prior art, methacryloxypropyltrimethoxysilane and methacryloxypropyImethyldiethoxysilane, wereincorporated into a poly(ethyl acrylate)latex and the post-application cross-linking of these latices was then compared with a reference poly(ethyl acrylate); (glass transition tem¬ perature: -24°C).

The post-application cross-linking of the latices was studied on the basis of the KGnig pendulum hardness (NEN 5319) and the solvent resistance to methyl ethyl ketone (MEK rubs, ASTM D 4752-87 which norm describes a relatively stringent variant of the MEK-test). The combination of these tests provides a measure for the degree of cross-linking in the cured paint film.

The determination of the MEK rubs was carried out with a hammer, a rough cloth (4 layers) being fixed to the hammer head, with a pressure on the coating of approximately 300 g/cm².

The combination of both these practical measuring methods generally gives a good indication of chemical curing.

The following latices were studied:

- latex 1: latex containing only ethyl acrylate

(reference)

- latex 3: poly(ethyl acrylate) latex containing 10 % by weight of methacryloxypropyltrimethoxysilane

- latex 4: poly(ethyl acrylate) latex containing 10 % by weight of methacryloxypropylmethyldiethoxy- silane

- latex 6: poly(ethyl acrylate) latex containing 10 % by weight of methacryloxypropylmethylbis(2,2,2- trifluoroethoxy)silane (according to the invention).

The latices were thickened, prior to use, with approximately 1 % of hydroxyethylcellulose (Natrosol* 250

MBR, Aqualon), based on the total composition. The preparation of the latices was carried out as described in the Examples 4, 6, 7 and 9.

After vapour degreasing with perchloroethylene, the latices were applied to glass plates, the latices being applied by means of a Bird applicator having a clearence of 150 micrometres. The thickness of the dried paint layer was approximately 17 micrometres, as determined by reflection measurements (Lichtschnitt method, ISO 2808, Method No. 5C).

The time between emulsion polymerization and the application to the substrate was 18 + 4 days for all dispersions.

After application of the paint, the plates were stored in a climatic chamber at 23°C and 50 % relative humidity. Then, at various times, the KGnig pendulum hardness was determined, and after 5 days the solvent resistance (MEK double rubs) was determined.

The results are shown in Table 3.

Table 3

MEK double rubs and Kϋnig impact hardness measurements as a function of the drying time for the four thickened latices layer KONIG HARDNESS (sec)

Lat thick¬ MEK³ ex ness 1/2 3h 1 2 2h 3 (μm) h RT day days 60^o1 days

RT RT RT 60^o1

1 15±2 8 8 8 8 8 8 1

3 19±2 8 7 7 7 13 ^" 1 20 4 16*2 10 10 13 13 15 17 5 6 16±2 6 7 8 8 11 17 5 i.e. 2 days at RT + 2 hours at 60°C in an oven i.e. 2 days at RT + 3 days at 60°C in an oven MEK double rubs (load: about 300 g/cm²)

(RT = room temperature)

The results stated in Table 3 show that the reference latex is not cross-linked after application, as a result of which the solvent resistance is very low and the hardness during drying remains low.

It is further found that the curing of the alkoxy- silyl latex containing the alkoxysilane of the invention (latex 6) is comparable to the curing of the alkoxysilyl latices from the prior art (latices 3 and 4).

The siloxanes of the invention show a lower hydroly¬ sis rate (as described in examples 2 and 3) and produce alkoxysilyl latices with less premature cross-linking than the siloxanes from the prior art, without this being at the expense of the post-application cross-linking in the ultimate applied paint layer.

Example 12 Determination of the post-application cross-linking in n- butylmethacrylate/alkoxysilyl latices. With the same purpose as, and analogous to example 11, one of the siloxanes of formulae I and II, methacryl¬ oxypropylmethyldi(2,2,2-trifluoroethoxy)silane (F), and a siloxan monomer from the prior art, i.e. the best monomer from the study by Bourne et al. , methacryloxypro¬ pyImethyldiethoxysilane (MAPMDES), were copolymerized with n-butylmethacrylate. Afterwards, the post-applica¬ tion cross-linking of said latices was compared with a reference latex (poly-n-butylmethacrylate; n-BMA or BMA). As compared to example 11, in which the polymer matrix comprised ethylacrylate, n-BMA has the advantage that the glass-transition temperature (Tg) of the homopolymer is substantially higher (about 25^βC as compared to about -24°C for p-ethylacrylate). Because of this it was expected that the post-application cross-linking should show up more clearly in a BMA-alkoxysilyl latex, than in the corresponding film formed out of the ethylacrylate latex.

The post-application cross-linking of the latices was studied on the basis of the Koenig pendulum hardness (NEN 5319), and the solvent resistance to methylethyl- ketone (MEK). In the present example, this last test was, however, carried out with a pressure to the head of the hammer which is more in line with the MEK-tests which is usually applied in the practice of research into paints (i.e. a pressure of about 60 g/cm²). On the head of the hammer a four-layer cheese cloth was applied, which was kept saturated with MEK continuously. The number of double MEK rubs was counted until the substrate was visible for the first time (due to softening and dis¬ solving of the film) or until the film showed rupture due to failing adhesion onto the substrate in the presence of the MEK, followed by the forming of cracks in the rela¬ tively brittle delaminated film. The coating properties and post-application cross- linking activity were studied for the pure n-BMA latex, a number of reference latices containing different types of thickeners or fillers (without built-in alkoxy silyl groups for post-application cross-linking) and analogously thickened n-BMA alkoxy silyl latices.

The latices studied are: - latex 2: reference latex with only n-BMA as a binder

(composition and synthesis described in example 5);

2a: reference latex 2 with a hydroxyethylcellulose thickener (HEC: Natrosol 250 MBR, Aqualon/Hercules).

The thickener concentration in the wet latex is 1.0 % of the total weight and the binder content is 20.8 wt.%; latex 2b: reference latex 2 with a silica filler (Aerosil 200, Degussa). The filler concentration of the wet latex is 3.75 % of total weight and the binder content is 20.8 wt.%; binder 2c: reference latex 2 with a silica-alumina- filler (Aerosil COK 84, Degussa). The filler concen¬ tration in the wet latex is 2.0 or 3.0 % of the total weight and the binder content is 20.8 wt.%; - latex 2d: reference latex 2 with a silica filler (Aerosil 380, Degussa). The filler concentration in the wet latex is 3.75 % of the total weight and the binder content is 20.8 wt.%; latex 5a: a latex on the basis of latex 5 (composi- tion and synthesis of latex 5 are mentioned in example 8; MAPMDES/n-BMA) thickened with a silica filler (Aerosil 200, Degussa). The filler concentra¬ tion in the wet latex is 3.75 % of total weight and the binder content is 20 wt.%. The binder contains 9.9 wt.% of a cross-linking monomer from the prior art.

A number of thickened latices on the basis of latex 7 (composition and synthesis of latex 7 are mentioned in example 10; F/n-BMA); the binder contains 9.6 wt.% of a cross-linking monomer according to the invention.

Latex 7a: a latex on the basis of latex 7 thickened with hydroxyethylcellulose (Natrosol 250 MBR, Aqualon/Hercules). The thickener concentration in the wet latex is 1.0 % of total weight and the binder content is 20 wt.%.

Latex 7b: a latex on the basis of latex 7 thickened with a silica filler (Aerosil 200, Degussa). The filler concentration in the wet latex is 3.75 % of total weight and the binder content is 20 wt.%;

Latex 7c: a latex on the basis of latex 7 thickened with a silica-alumina filler (Aerosil COK 84, Degussa). The filler concentration in the wet latex is 2.0 % of total weight and the binder content is

20 wt.%;

Latex 7d: a latex on the basis of latex 7 thickened with a silica filler (Aerosil 380, Degussa). The filler concentration in the wet latex is 3.75 % of total weight and the binder content is 20 wt.%.

The latices were applied onto glass plates with a

Bird applicator with a clearence of 150 μm. The thickness of the layer after drying was 20-25 μm, as determined by reflection measurements (Lichtschnitt method, ISO 2808,

Method No. 5C). The standard deviation of the thickness of the layer per panel was usually ± 2.0 μm. After applying the top coat the painted glass plate was dried during about 30-45 min. at about 55°C and in some cases at 23 or 70^βC. Immediately thereafter the test plate was stored at 23°C and 50 % humidity. The short period of elevated temperature during the first phase of the drying of the film (particularly evaporation of water) is carried out to form a coalesced film without cracks (the Tg of the coating is about 23-35°C).

The pH of the thickened and non-thickened latices (about 6.3-7) was optionally adjusted just before appli¬ cation so as to catalyse the post-application cross- linking activity. This was carried out about 5 minutes before application of the latex by means of ammonia or sodium hydroxide and/or acetic acid, and in cases of a relatively low pH, with hydrochloric acid or sulfuric acid.

The results of the measurements of the KGnig pendu¬ lum hardness and the MEK resistance are mentioned in table 4.

Table 4

Coating properties of the studied reference latices and the alkoxysilyl/n-butylmethacrylate latices.

LATEX THICKENER pH FILM KONIG-HARD- MEK

/ FILLER FORMING NESS (s)^* DOUBLE TEMPERA¬ RUBS TURE °C (30-45 MINUTES)

2 NONE 6.5- 55 ld:31±2Δ ca.

(N-BMA) 7.0 5-S^** ΔΔ

2a HEC 6,5 55 8d: 43±1 (1,0%)

8.86 55 8d: 29±1

11.00 55 8d: 28±1

2b AER. 200 6.5 50-55 l-6d: 45±2 5-S^**

(3.75%) 3.8 l-6d: 45+2 5-S

10.3 l-6d: 45±2 5-S

6.5 70 5d: 45±1 5-S

2c COK 84 6.5 70 l-6d: 38±2 5-S (2%)

COK 84 6.3 55 l-8d:42-50

(3%) 3.0 55 l-20d:45-48

11.0 55 l-20d:38-43 2d AER. 380 6.3 55 l-6d: 45-48 10-S

(3.75%) 2.9 l-6d: 46-48 10-S

10.2 l-6d: 47-51 10-S

5a AER. 200 6.5 55 lu: 52±3 Id: 62±4

(MDES/ 6d: 74±10

BMA) +5d 55°: 78±5 >300

6.16 55 2u: 84±10 Id: 82±8 6d: 90±2 >200

6.5 75 lu: 82±6 4d: 83±2 +5d.50°: 76±11 >200

3.8 65 Id: 88±8 12d: 83±10 >200

2.9 55 Id: 90±6 4d: 100 >200

10.2 55 2u: 78±8 Id: 81±5 6d: 87±5 >200

7a HEC 6.4 55 Id: 44±1 (1.0%) 6d: 47+2

(F/BMA) +5d 55°: 64±3 150 inven¬ tion 2.5 55 Id: 46±2 6d: 48+2 +5d 55°: 58±4 30-C^**

10.4 55 Id: 27+1 6d: 27+1 +5d 55°: 31±1 5-G

7b AER. 200 6.5 23 2h: 64±1 inven¬ (3.75%) Id: 80±1 tion 6d: 77±1

+5d 55°: 86+2 7-C

6.5 55 2h: 52±2 Id: 72±1 6d: 74±2 6d.23°+ +5d.55°: 84±2 7-C*

4.0 55 Id: 47±2 6d: 55±5 +7d.55°: 95+2

3.8 55 3d: 60±6 lOd: 85±5 10-C

2 55 3d: 96±3 6d: 96±4 +7d.55°:lll±6

7c C0K84 6.5 55 lh: 63±5 inven¬ (2.0%) 5d: 63±6 tion 13d: 75+5 12-C d AER. 380 6.0 55 Id: 50±2 (3.75%) 5d: 48±1 +8d.55°: 57±2 9-C

1.9 55 Id: 100±5 7d: 90±9 +6d.55°: 99±7 140-S

10.18 55 Id: 57±7 8d.23°+ +8d.55°: 80 7-C

11.55 55 3d: 62±9 7d: 69±4 +7d.55°: 70±2 200-S

12.9 55 3d: 64±10 7d: 95±8 15d.23°+ 6d.55°:125±12 90-C

*: temperature during storing of the coated panel is 23°C (50 % R.H.), unless otherwise mentioned; d: day; h: hours.

Δ: Instead of 20-25 μm the layer thickness was in this case 53 ± 13 μm.

ΔΔ: About 5 MEK double rubs when normalised on a thick¬ ness of 20-25 μm. In reality the thickness was 53 + 13 μm and the number of double rubs was 10-15.

**S: the substrate becomes visible during the MEK rub test for the first time due to softening and dis¬ solving of the binder.

**C: the coating fails during the MEK rub test due to delamination (failing adhesion on the glass plate) and the formation of cracks in the relatively brittle film thus obtained.

#: resistance to ethanol: > 250 double rubs (test analogous to MEK rubs) water resistance: > 250 double rubs (demineralised water; test analogous to MEK rubs). The results illustrate the following aspects:

* The reference latices with or without thickener or filler do not undergo post-application cross-linking, so that the resistance to solvents is very small (due to the softening and dissolving of the binder under the influence of MEK) and the KGnig pendulum hardness is low. This is also true for films which are dried during 40 minutes at 70°C immediately after application (so as to favor coalescence) so that it is assumed that any resi- dual persulfate initiator, due to the emulsion polymerisation process, does not or not significantly contribute to any chemical post-application cross-linking in the latex film.

* As compared to the reference latices the alkoxy silyl latices MDES/BMA and F/BMA show a clear post- application cross-linking activity, as can be seen from the substantially higher KGnig hardness and solvent resistance. The latices containing the methacryloxypro¬ pylmethyldi(2,2,2-trifluoroethoxy)silane-monomer of the invention or the MDES monomer according to the prior art, show a comparable post-application cross-linking activity, although the F-monomer according to examples 2 and 3 is substantially less susceptible to hydrolysis than MDES, the alkoxy silyl monomer from the studies of Bourne et al. which was most resistant to hydrolysis. The KGning pendulum hardness of the films kept at 23°C reached for both monomer types hardness values between 80 and 100 seconds, depending on the type of thickener/filler and the pH. By additional moderate heating (up to 55°C) the F/BMA latices can crosslink to hardness values of about 90-125 seconds. The MEK resis¬ tance of the corresponding top coats are for films on the basis of MDES/BMA better than for tops coats on the basis of F/BMA. It is however remarked that the failure of the F/BMA films is not due to softening or dissolving of the binder, but due to delamination from the glass substrate causing the coating to crack due to brittleness. Brittle behavior is an indication for post-application cross- linking, because the corresponding reference films do not show brittle behavior in the MEK rub test; these reference films fail because the binder is dissolved. * In order to accelerate the post-application cross- linking reaction at ambient temperature a catalytic effect is required. The results from table 4 showed that the rate and degree of post-application cross-linking is strongly determined by: - the thickener or filler used.

Both the type as well as the concentration are important. For instance, using hydroxyethylcellulose in the F/BMA latex (latex 7a) leads to slow post- application cross-linking, but silica types such as Aerosil 200 and Aerosil 380 show a stronger catalytic activity (latices 7b and 7d respectively), the pH of the wet latex. Both acid as well as base can catalyse the post-applica¬ tion cross-linking reaction, the degree of efficiency being strongly dependent upon the type of filler. On the basis of this principle the post-application cross- linking reaction can be accelerated by using a volatile pH-buffer, preferably in combination with one or more other catalysts, such as silica, silicate or another filler or pigment, a metal salt or an organometal com¬ pound.

* The examples 12, 2 and 3 illustrate that by using a (-1) effect due to the presence of an electronegative substituent in one of the alkoxy groups bound to the silane monomer of type I or II, it is possible to sig¬ nificantly reduce the susceptibility to hydrolysis of the silane monomer without significantly reducing the ability to provide post-application cross-linking of a latex film containing such a monomer according to the invention.

Example 13

Preparation of a coating composition according to the invention

A specific example of a paint preparation on the basis of a siloxane-modified binder looks as follows:

60 ml of demineralized water is admixed with 1.7 g of Orotan 731 (Rohm & Haas: a 25 per cent premix of a dispersant on the basis of an acidic copolymer), 0.2 g of Triton CF-10 (Rohm & Haas: a surface-active substance), 0.1 g of Dowicil 75 (Dow: a biocide) and 1.0 g of Byk 24 (Byk-Chemie: an anti-foaming agent). In this mixture, 80 g of Kronos 2190 (Kronos B.V./NL Chemicals: a rutile titanium dioxide pigment) and 6.0 g of silica Aerosil 200 (Degussa) are dispersed at high speed (Cowles dispersing apparatus) until the fineness of grind is 8 μm (Hegman gauge). The pH is adjusted to 7. At a moderate stirrer speed this is admixed with: 200 g of latex as described in Example 10, 42 g of a 3.0 per cent premix of SER AD FX 1100 (Servo Delden B.V.: an associative polyurethane thickener) and 0.5 g of Byk 24 (Byk-Chemie: an anti- foaming agent). The solids content of the paint is 42 % and the pigment volume concentration (PVC) is 21 %.

Example 14

In further experiments carried out as described hereinabove it was shown that the corresponding 2,2,2- trichloroethoxysilane showed a rate of hydrolysis that is even less than that of methacryloxypropylmethylbis(2,2,2- trifluoroethoxy)silane.

Claims

1. Siloxanes having the formula

O R,

II ⁱ²

R. - C - O - X - Si - 0R₃ I 0R₄ wherein

R-_L is an optionally substituted alkenic group having 2-10 carbon atoms,

R₃ and R₄ each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaro¬ matic group, or wherein the R₃ and R₄ groups, together with the oxygen atoms to which they are bound and the silicon atom, form an optionally substituted ring structure, or wherein one of the groups R₃ or R₄, together with the oxygen atom to which it is bound, the silicon atom and the R₂ group, forms an optionally substituted ring structure, at least one of the groups R₃ or R₄ having a greater electronegativity than the methyl group.

2. Siloxanes according to Claim 1, wherein both groups R₃ and R₄ have a greater electronegativity than the methyl group.

3. Siloxanes according to Claim 1 or 2, wherein at least one of the groups R₃ or R₄ carries one or more substituents which are more electronegative than the methyl group.

4. Siloxanes according to any one of Claims 1-3, wherein both groups R₃ and R₄ carry one or more substi- tuents which are more electronegative than the methyl group.

5. Siloxanes having the formula

0 R₂

// '

R, - C - 0 - X - Si - 0R₃ II

I R₂' wherein

R-_ and X have the meanings given in Claim 1, and

R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substi¬ tuted aromatic group, an optionally substituted hetero¬ aromatic group or an optionally substituted silylalkyl group, or wherein R₂ and R₂', together with the silicon atom to which they are bound, form an optionally substi¬ tuted ring structure,

6. Siloxanes according to Claim 5, wherein the group R₃ carries one or more substituents which are more electronegative than the methyl group.

7. Siloxanes according to any one of Claims 1-6, wherein the electronegative substituents are bound to the α carbon atom or the β carbon atom and preferably the α carbon atom of the R₃ and/or R₄ group.

8. Siloxanes according to any one of Claims 1-7, wherein the electronegative groups R₃ and R₄ and/or the electronegative substituents on the groups R₃ and R₄ have an inductive effect on the hydrolysis of the silyl ether bond.

9. Siloxanes according to any one of Claims 1-8, wherein the electronegative substituents on the groups R₃ and R₄ have an inductive effect on the hydrolysis of the silyl ether bond.

10. Siloxanes according to any one of Claims 1-9, wherein the electronegative substituent is chosen from the group comprising CF₃, CC1₃, CN, nitro, halogen, -0-C0-R₅, -C0-0R₅, -(C=0)-R₅, -CR₅=CR₅R₆ and -NR₅R₆, in which R₅ and R₆, independently, is H or an optionally substituted alkyl group, alkenic group, alkynic group or aromatic group, is preferably chosen from the group comprising CF₃, CC1₃, CN, N0₂ and halogen, and most preferably is -CF₃ and/or CC1₃.

11. Siloxanes according to any one of Claims 1-10, wherein the R_x group is an optionally substituted ethene group, preferably an ethene group or a 1-methylethene group and most preferably a 1-methylethene group.

12. Siloxanes according to any one of Claims 1-11, wherein the linking group X is an optionally substituted alkyl group having 1-6 carbon atoms, preferably an optionally substituted alkyl group having 3-4 carbon atoms and more preferably is an n-propyl group.

13. Siloxanes according to any one of Claims 1-12, wherein the R₂ and R₂' group, independently, are an optionally substituted branched or straight-chain, cyclic alkyl group having 1-6 carbon atoms or a substituted phenyl group, and preferably are a methyl, ethyl, propyl, isopropyl, t-butyl or phenyl group.

14. Siloxanes according to any of Claims 1-13, wherein the groups R₃ and/or R₄ contain 1-20 carbon atoms and optionally one or more heteroatoms and are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group.

15. (Meth)acryloxypropylmethylbis(2,2,2-trifluoro¬ ethoxy)silane, (met )acryloxypropylmethylbis(2,2,2- trichloroethoxy)silane, (meth)acryloxypropyldimethyl- (2,2,2-trifluoroethoxy)silane or (meth)acryloxypropylme- thylbis(2,2,2-trichloroethoxy)silane.

16. Siloxanes according to any one of Claims 1-14, wherein at least one of the groups R₂, R₂', R₃ and R₄ contains a surface-active group, chosen from anionic, cationic, ampholytic and non-ionic surface-active groups.

17. Use of siloxanes having the formula

wherein R_x is an optionally substituted alkenic group having 2-10 carbon atoms,

R₂ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substi- tuted aromatic group, an optionally substituted hetero¬ aromatic group or an optionally substituted silylalkyl group,

R₃ and R₄ each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ and R₄ groups, together with the oxygen atoms to which they are bound and the silicon atom, form an optionally substituted ring structure, or wherein one of the groups R₃ or R₄, together with the oxygen atom to which it is bound, the silicon atom and the R₂ group, forms an optionally substituted ring structure, at least one of the groups R₃ or R₄ having a greater electronegativity than the methyl group, or formula II

0 R,

II I

R, - C - 0 - X - Si - OR, II

I wherein R and X have the meanings given in Claim 1, and

R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substituted aromatic group, an _-_Λ

- 50 - optionally substituted heteroaromatic group or an op¬ tionally substituted silylalkyl group, or wherein R₂ and R₂' , together with the silicon atom to which they are bound, form an optionally substituted ring structure, R₃ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ group, together with the oxygen atom to which it is bound, the silicon atom and one of the groups R₂ and R₂', forms an optionally substituted ring struc¬ ture, the group R₃ having a greater electronegativity than the methyl group, in the preparation of coating compositions.

18. Coating composition containing one or more siloxanes of formula I

0 R,

II I

R_x - C - 0 - X - Si - 0R₃ I

0R₄ wherein R is an optionally substituted alkenic group having 2-10 carbon atoms,

0 R,

II i ^z

R, - C - 0 - X - Si - OR, II i ³

V wherein Rj and X have the meanings given in Claim 1, and

R₂ and R₂' each contain 1-20 carbon atoms and optionally one or more heteroatoms and, independently, are an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted alkynic group, an optionally substituted ester group, an optionally substituted aromatic group, an optionally substituted heteroaromatic group or an op¬ tionally substituted silylalkyl group, or wherein R₂ and R₂', together with the silicon atom to which they are bound, form an optionally substituted ring structure, R₃ contains 1-20 carbon atoms and optionally one or more heteroatoms and is an optionally substituted branched, straight-chain or cyclic alkyl group, an optionally substituted branched, straight-chain or cyclic alkenic group, an optionally substituted branched, straight-chain or cyclic alkynic group, an optionally substituted carbonyl group, an optionally substituted aromatic group or an optionally substituted heteroaromatic group, or wherein the R₃ group, together with the oxygen atom to which it is bound, the silicon atom and one of the groups R₂ and R₂' , forms an optionally substituted ring struc¬ ture, the group R₃ having a greater electronegativity than the methyl group.

19. Coating composition according to Claim 18 which contains one or more siloxanes according to Claim 15.

20. Coating composition according to Claim 18 or 19, in which the alkoxysilane compounds are present to an amount of 0.001-25 mol%, preferably an amount of 0.1-5 mol%, based on the monomeric constituents of the polymeric constituent.

21. Coating composition according to any one of Claims 18-20, wherein said composition comprises 0.1-10% by weight of (meth)acrylic acid, based on the polymeric binder.

22. Coating composition according to any one of Claims 18-21, wherein the composition comprises a water-based dispersion paint, in particular an acrylic paint.

23. Use of a coating composition according to any one of Claims 18-22 in coating a substrate or product.

24. Substrate or product coated with a coating composi- tion, wherein the substrate or product is coated with one or more coating compositions according to any one of

Claims 17-21.

***