GB2042559A - Method for curing a vinyl polymer - Google Patents

Abstract

A method for curing a vinyl polymer containing an acetoacetate group in the molecule by reacting it with an organic metal compound of aluminium, titanium, or zirconium containing alkoxy groups, alkenyloxy groups or organic oxy groups containing a carbonyl group and the residues of beta-dicarbonyl or beta-hydroxycarbonyl compounds. Also provided is a storage stable solution of a composition containing said vinyl polymer and said organic metal compound. A curing reaction between the two does not occur in the solution, but when the solution is coated and dried, a cured film having superior transparency, ultraviolet resistance, chemical resistance and solvent resistance is formed.

Description

SPECIFICATION Method for curing a vinyl polymer This invention relates to a method for curing a vinyl polymer. More specifically, it relates to a method for curing a vinyl polymer having an acetoacetate group, a solution of a vinyl polymer composition suitable for the formation of a coating of a cured vinyl polymer which has good storage stability, and also to an organic metal compound for said curing.

Despite the fact that vinyl polymers generally have superior transparency and resistance to ultraviolet light, theirthermoplasticity has limited extensive application. Accordingly, some attempts have been made to extend the utility of vinyl polymers by curing them to polymers of a three-dimensional structure. For example, a method is known for curing a vinyl polymer having a hydroxyl group in the molecule with an amino resin such as a urea or melamine resin. This method, however, usually requires a relatively high temperature of 80 to 200"C and a period of about 10 to 30 minutes for curing, and retracts from the today's demand for energy saving.

A method is also known which comprises curing a vinyl polymer containing a hydroxyl group in the molecule with an isocyanate compound at relatively low temperatures. According to this method, curing can be carried out usually at a temperature of 5 to 80"C. The vinyl polymer and the isocyanate cannot be mixed until just before the curing operation because the reactivity of the hydroxyl group with the isocyanate group is high. It is necessary therefore to store the vinyl polymer and the isocyanate compound as two separate solutions, and mix them just before use (the two-package method), and the operation is complicated.

A method for curing an acrylic polymer is also known which comprises mixing an acrylic polymer having an epoxy group and/or a hydroxyl group in the molecule with an intra-molecular complex compound of a carboxylic acid ester having a carbonyl or hydroxyl group at the beta-position coordinated with a central atom, and reacting the mixture (see Japanese Patent Publication No. 9073/70). The curing reaction in this method is advantageously carried out generally by heat-treating the mixture at a temperature of 150 to 1800C for 10 to 30 minutes. Attempt to effect curing at room temperature in this method may sometimes result in a cured coated film. However, the resulting coating contains a great amount of a portion which dissolves in an organic solvent such as an alcohol or Cellosolve upon immersion therein.

It is an object of this invention, therefore, to provide a method for curing a vinyl polymer at room temperature to give a cured coating having superior properties.

Another object of this invention is to provide a solution having good storage stability of a vinyl polymer composition comprising a vinyl polymer and a curing ingredient.

Still another object of this invention isto provide ari organic metal compound as a curing ingredient which is conductive to curing of a vinyl polymer at room temperature to give a cured coated film having superior properties.

Other objects of this invention will become apparent from the following description.

These objects and advantages of this invention are achieved in accordance with this invention by a method for curing a vinyl polymer, which comprises reacting a vinyl polymer containing an acetoacetate group in the molecule with an organic metal compound of the following formula

wherein M is Al, Ti, or Zr; OR', OR3, OR2, and OR4 are identical or different, and each represents an alkoxy group, an alkenyloxy group, or an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound, or any two of OR', OR2, OR3, and OR4 are bonded to each other to form an alkylenedioxy group; n is a number of from 0 to 10; and m is a number determined by the atomic valence of M and/or the coordination number of M, and isO or 1.

The vinyl polymer containing an acetoacetate group used in this invention may contain other active groups capable of reacting with the organic metal compound used in this invention as a curing agent, such as a hydroxyl or carboxyl group, or inert groups which do not react with the metal compound, for example halogen atoms such as chlorine or bromine.

A preferred species of the vinyl polymer used in this invention is a vinyl polymer having at least 5 mole %, preferably at least 10 mole %, of a monomeric unit containing an acetoacetate group. The vinyl polymer used in this invention may be a homopolymer or a copolymer.

The vinyl polymer containing an acetoacetate group can be advantageously produced by (1) polymerizing at least one vinyl monomer containing an acetoacetate group, or polymerizing at least one vinyl group containing an acetoacetate ester with another monomer not containing an acetoacetate group; or (2) polymerizing at least one vinyl mono mer having no acetoacetate group but having a reactive group convertible to an acetoacetate ester group, or polymerizing such a vinyl monomer with another monomer which does not contain a reactive group convertible to an acetoacetate group.

The vinyl monomer containing an acetoacetate group can be easily produced by reacting a vinyl monomer containing a hydroxyl group with diketene.

Examples of the vinyl monomer having a hydroxyl group are 2 - hydroxyethyl methacrylate, 2 - hydroxyethyl acrylate, 2- hydroxypropyl methacrylate, 2 hydroxypropyl acrylate, allyl alcohol, 3 - chloro - 2 hydroxypropyl methacrylate, 3 - chloro -2 - hydrox- ypropyl acrylate, polyethylene glycol monome hacrylate, and polypropylene glycol monomethacrylate.

A compound of the following formula

wherein n is a number of from 2 to 10, preferably 5 to 6, as preferred as the polyethylene glycol monomethacrylate. As the polypropylene glycol monomethacrylate, a compound of the formula

wherein mis a number of from 2 to 10, preferably 5 to 6, is preferred.

Reaction of the aforesaid hydroxyl-containing vinyl monomer with diketene yields a vinyl monomer having an acetoacetate group. Accordingly, the vinyl monomer containing an acetoacetate group in this invention denotes a monomer containing both an acetoacetate group and a polymerizable unsaturated bond, such as the one obtained by the reaction of 2hydroxyethyl methacrylate with diketene and having the following tormula:

Examples of the monomer not containing an acetoacetate group include styrene, vinyltoluene, N-vinylpyrrolidone, acrylates such as methyl acry late or ethyl acrylate, methacrylates such as methyl methacrylate or ethyl methacrylate, itaconic esters, maieic esters, fumaric esters, crotonic esters, acrylonitrile, and methacrylonitrile.

Vinyl monomers having a hydroxyl group such as those exemplified hereinabove, and vinyl monomers having a free carboxyl group such as methacrylic acid, fumaric acid, acrylic acid, maleic acid, crotonic acid or itaconic acid may equally be used.

The vinyl polymer containing an acetoacetate group can be produced by polymerizing at least one monomer containing an acetoacetate group, or polymerizing at least one such monomer with another monomer not containing an acetoacetate group.

The other monomer is desirably used in an amount of not more than 95 mole %, preferably not more than 90 mole %, based on the entire monomers used. When the other monomer is a hydroxyl- or carboxyl-containing monomer, it is preferably used in an amount of not more than 10 mole %.

The vinyl polymer containing an acetoacetate group used in this invention, as stated hereinabove, may also be produced by polymerizing at least one vinyl monomer having no acetoacetate group but having a reactive group capable of being converted to an acetoacetate group, or by polymerizing at least one such vinylmonomerwith at least one other monomer which does not contain a reactive group convertible to an acetoacetate group.

The vinyl monomer having a reactive group con vertibleto an acetoacetate group includes not only the aforesaid vinyl monomers having a hydroxyl group, but also derivatives of the hydroxylcontaining vinyl monomers resulting from esterification of the hydroxyl group thereof, such as 2-acetoxyethyl methacrylate or 2-propionyloxyethyl acrylate, and monomers containing an epoxy group such as glycidyl methacrylate and glycidyl acrylate.

Since a polymer from the hydroxyl- or epoxycontaining vinyl monomer is formed as a hydroxylcontaining polymer, subsequent reaction of the polymer with diketene can yield the polymer containing an acetoacetate group in accordance with this invention.

On the other hand, a polymer from the vinyl monomer having an ester group, such as 2-acetoxyethyl methacrylate or a vinyl acetate, may be hydrolyzed to convert the ester group to a hydroxyl group, and subsequently reacted with diketene to form the polymer containing an acetoacetate group in accordance with this invention.

In the polymerization reaction, one or more vinyl monomers having a reactive group convertible to an acetoacetate group may be used. Thus, when a vinyl monomer containing a hydroxyl or epoxy group and a vinyl monomer containing an ester group are used together, the resulting copolymer may be reacted with diketene either directly or, as desired, after it is hydrolyzed. The need for hydrolysis can be easily determined by the amount of the vinyl monomer having an ester group.

Furthermore, in the above polymerization process, at least one other monomer not containing a reactive group convertible to an acetoacetate group may be used as a copolymer component. The other monomer may include the same compounds as those already exemplified hereinabove for the other monomer not containing an acetoacetate group, excluding vinyl monomers having a hydroxyl group.

The amount of the other monomer is desirably not more than 95 mole %, especially not more than 90 mole %.

The aforesaid polymerization reaction and hydrolysis reaction are knownperse, and these known reactions are also used in this invention.

For the production of the polymer containing an acetoacetate group in this invention, the vinyl monomer having a hydroxyl group orthe vinyl polymer having a hydroxyl group, for example, is reacted with diketene.

Diketene is a compound of the following formula

and is known as a colorless liquid which gives off a strong irritating odor of Iachrymatic nature and which has a melting point of 6.5"C, a boiling point of 127.4"C, n20 of 1.4379, d2020 of 1.0897 and a vapor pressure (20 C) of 8.0 nm (A. B. Boese, Ind. Eng.

Chem.,32, 16 (1940)).

In the present invention, the reaction with diketene is advantageously carried out preferably in the presence of an acid or basic catalyst in an aprotic organic solvent having no active hydrogen.

The acid catalyst may, for example, be hydrochloric acid, trichloroacetic acid, dichloroacetic acid, monochloroacetic acid, acetic acid, formic acid, phthalic anhydride, cobalt nitrate and p-toluenesulfonic acid. As the basic catalyst, potassium acetate and sodium acetate can, for example, be used.

Examples of the aprotic organic solvent having no active hydrogen include ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl n-butyl ketone, methyl amyl ketone, ethyl amyl ketone, diethyl ketone, ethyl butyl ketone, methyl hexyl ketone, cyclohexanone and isophorone; esters such as ethyl acetate, methyl propionate, n-butyl acetate, isobutyl acetate, amyl acetate, methyl amyl acetate, ethylene glycol monoethyl ether acetate (Cellosolve acetate), 2-ethylhexyl acetate, diethyleneglycol monoethyl ether acetate (carbitol acetate), 3methoxybutyl acetate, cyclohexyl acetate, and ethylene glycol monomethyl ether acetate (methyl ellosolve acetate); aliphatic hydrocarbon solvents such as petroleum, ligroin, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, methyl cyclohexane, 1,1 -dimethyl cyclohexane, ethyl cyclohexane, n-propyl cyclohexane, and n-butyl cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene and trimethyl benzene; and mixtures thereof.

The reaction is carried out by dissolving a vinyl monomer having a hydroxyl group or a vinyl polymer having a hydroxyl group in the aprotic organic solvent, adding diketene to the solution with stirring, maintaining the mixture at room temperature to 70"C for 10 minutes to 10 hours preferably in the presence of the acid or basic catalyst. Advantageously, the catalyst is used in an amount of 0.01 to 10% by weight, especially 0.1 to 1% by weight, based on the monomer or polymer.

Stoichiometrically, this reaction is between 1 equivalent weight of the hydroxyl group with 1 mole of diketene. But in practice, diketene can be used in an amount either smaller or larger than the stoichiometrical amount. Usually, the amount of diketene is in the range of 0.1 to 2.0 moles per equivalent weight of the hydroxyl group. After the reaction, the excess of diketene can be removed out of the system by reaction with alcohol.

The end point of this reaction can be easily determined by infrared absorption spectroscopy. The absorption of the acetoacetate group formed by the reaction appears at 1750 cm-', and is clearly distinguishable from the absorptions of the starting material (e.g., acrylate or methacrylate esters). The absorption at 1610 cm-1 based on a carbon-carbon double bond due to the formation of the enol form of acetoacetate appears as a shoulder of the absorptions at 1630 to 1640cm1 based on a carbon-carbon double bond due to the formation of the enol form of acetoacetate appears as a shoulder of the absorptions at 1630 to 1640 cm-' of the acrylate or methacrylate ester used as the starting material.Accordingly, the end point of the reaction is determined by tracing the absorptions at 1750cm1 and 1610 cm-', and is defined as the point at which the absorptions become maximum with no further change in absorption intensity.

Thus, according to the above reaction, the vinyl polymer in accordance with this invention containing at least 5 mole %, preferably at least 10 mole %, of an acetoacetate group can be produced.

An especially preferred vinyl polymer containing an acetoacetate group in accordance with this invention is a polymer obtained by reacting a hydroxylcontaining vinyl polymer with a ketone.

The organic metal compound used as a curing ingredient for the vinyl polymer containing an acetoacetate group is a compound expressed by the following formula:

In the above formula, M is Al, Ti, orZr; ORr, OR2, OR3, and OR4 are identical or different and each represents an alkoxy group, an alkenyloxy group, or an organic oxy group containing a carbonyl group as the residue of a beta-dicarbonyl compound or betahydroxycarbonyl compound, or any two OR1, OR2, OR3, and OR4 are bonded to each other to form an alkylenedioxy group; n is a number of from 0 to 10; and m is a number determined by the atomic valence and/or coordination number of M, and isO or 1.

Preferred alkoxy or alkenyloxy groups in formula (I) are those having 1 to 20 carbon atoms, preferably 1 to 18 carbon atoms, for example alkoxy groups such as methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, t-butoxy, sec-butoxy, iso-butoxy, n-pentoxy, n-hexoxy, n-heptyloxy, n-succinyloxy, n-lauryloxy, and n-stearyloxy, and the corresponding alkenyloxy groups.

The organic oxy group containing a carbonyl group as the residue of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound in formula (I) is the residue of the enol form of the beta-dicarbonyl compound or the residue of the betahydroxycarbonyl compound, and denotes an organic oxy group containing a carbonyl group having Al, Ti orZr represented by M bonded in place of the hydrogen atom of the hydroxyl group.

Examples of such beta-dicarbonyl compound are beta-diketones such as acetylacetone, acetoacetates such as methyl acetoacetate and ethyl acetoacetate, and malonic acid esters such as methyl malonate, ethyl malonate, dimethyl malonate, diethyl malonate and propyl malonate.

Examples of the beta-hydroxycarbonyl compound are beta-hydroxyketones such as diacetone alcohol, beta-hydroxyaldehydes such as salicylaldehyde and 5-methylsalicylaldehyde, and esters having a hydroxyl group at the beta-position such as methyl salicylate.

The alkylene dioxy groups in formula (I) include, for example, the residues of glycols, such as ethylene glycol, 1,3-butanediol, 2 ethylhexanediol-1 ,3, and 2-methylpentanediol-2,4.

In the above formula (I), n is a number of from 0 to 10, and m is a number determined by the atomic valence and/or coordination number of M, and is0 or 1.

The organic metal compounds of formula (I) have in common the function of a curing ingredient capable of curing a vinyl polymer having an acetoacetate group. For purposes of illustration, these organic metal compounds are classified into the following three groups by the definition of M.

A first group includes compounds in which M is Al, and is expressed by the following formula (I)-a.

wherein OR1, OR2, and OR3 are the same as defined above.

Examples of the compounds of formula (I)-a are aluminum alkoxides such as aluminum trimethoxide, aluminum triethoxide, aluminum tri-npropoxide, aluminum tri-i-propoxide, aluminum tri-n-butoxide, aluminum tri-i-butoxide, aluminum tri-sec-butoxide, and aluminum tri-t-butoxide. Of these aluminum triisopropoxide, aluminum tri-secbutoxide and aluminum tri-n-butoxide are especially preferred.

Compounds of formula (I)-a which contain an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound can be produced by reacting the aforesaid aluminum alkoxides with beta-dicarbonyl compounds or betahydroxycarbonyl compounds. This reaction proceeds easily by simply mixing these materials at room temperature. In this reaction, it is preferable to use not more than about4 moles of the betadicarbonyl compound or beta-hydroxycarbonyl compound per mole of the aluminum alkoxide.

In the present invention, the organic metal compound having an organic oxy group may be mixed with the vinyl polymer containing an acetoacetate group after forming it by such a reaction. Alternatively, such a reaction may be performed in situ in the vinyl polymer.

Organic metal compounds containing an organic oxy group which is the residue of an acetoacetate or beta-diketone are preferred.

It will be appreciated from the above description that the organic aluminum compounds of formula (I)-a embrace aluminum tripropoxide of the formula

aluminum triacetylacetonate of the following formula resulting from the attachment of3 moles of acetylacetone to one aluminum atom

and compounds such as aluminum diisopropoxy monoacetylacetonate resulting from the attachment of 2 moles of isopropoxy group 1 and 1 mole of acetylacetone to one aluminum atom as shown by the following formula:

It will also be understood that these compounds correspond to formula (I) in which m=n=O, and in which the atomic valence of aluminum is 3, andfor the coordination number is 6.Specifically, the compounds of formula (1) and (3) are compounds in which the aluminum has a valence of 3, and the compound of formula (2) is a compound in which the valence of aluminum is3 and the coordination number is 6.

A second group includes compounds of formula (I) in which M is Ti, and is expressed by the following formula.

In the above formula, all symbols have the same meanings as defined hereinabove.

Of these compounds, organic titanium compounds of the following formula are preferred.

In formula (I)-b', OR", OR2', OR3' and OR4' represent an alkyl group containing 1 to 20 carbon atoms, an alkenyl group containing 2 to 20 carbon atoms, or an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or a beta-hydroxy-carbonyl group, and n and m are as defined hereinabove.

Examples of the organic titanium compounds of the formula (I)-b (including (I)-b') include compounds in which n is 0, such as tetramethyl titanate, tetraethyl titanate, tetra-n-propyl titanate, tetra-isopropyl titanate, tetra-t-butyl titanate, tetra-n-butyl titanate, tetra-iso-butyl titanate, tetra-n-pentyl titanate, tetra-n-hexyl titanate, tetra-iso-octyl titanate, and tetra-n-lauryl titanate; and compounds in which n is 1 to 10, such as dimes to undecamers of the above-exemplified tetra-iso-propyl titanate, tetra-nbutyl titanate, tetra-iso-butyl titanate, tetra-t-butyl titanate, etc.

Organic titanium compounds of formula (I)-b which contain an organic oxy group containing a carbonyl group which is the residue of a betadicarbonyl compound or beta-hydroxycarbonyl compound can be produced by reacting the aforesaid titanium alcoholates with beta-dicarbonyl compounds and beta-hydroxycarbonyl compounds.

Organic titanium compounds having an organic oxy group which is the residue of an acetoacetate or beta-diketone are especially preferred.

Since titanium has an atomic valence of 4 and a coordination number of 6, the organic titanium compounds in this invention include compounds having the valence and/or the coordination number specified, such as titanium triisopropoxy monoacetyl acetonate, titanium diisopropoxy diacetyl acetonate, and titanium triacetyl acetonate.

Athird group includes compounds offormula (I) in which M is Zr, and is expressed by the following formula.

In formula (I)-c, all symbols are as defined hereinabove.

Among the organic zirconium compounds of formula (I)-c, those of the following formula are especially preferred.

In formula (I)-c', OR", OR2', OR3' and OR4' and m are the same as defined hereinabove, and p is a number of from 0 to 5. Examples of the organic zirconium compounds expressed by formula (I)-c (including formula (I)-c') include tetra- to penta-mer of tetraethyl zirconate (n or p=3A), a tetramer of tetra-iso-propyl zirconate (nor p=about3), a dimer of tetra-t-butyl zirconate (n orp=1), a diameter of tetra-sec-butyl zirconate (n or p 1), a tetra- to penta-mertetra-n-pentyl zirconate (n or p=3 or4) a dimer of tetra-t-pentyl zirconate (n or p=1), a dimer of tetra-t-hexyl zirconate (n or p=1), an approximately tetramer of tetra-n-heptyl zirconate (n =about 3), a tetra- to penta-mer of tetra-n-octyl zirconate (n or p=34), tetra-n-stearyl zirconate, tetra-iso-propyl zirconate, and tetra-n-butyl zirconate.

Of these, tetra-iso-propyl zirconate and tetra-nbutyl zirconate are especially preferred.

Those organic zirconate compounds expressed by formula (I)-c which contain an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound can be produced by reacting the aforesaid zirconium alcoholates with betadicarbonyl compounds or beta-hydroxycarbonyl compounds, as already described hereinabove with regard to the organic aluminum compounds (first group).

Among these, organic zirconium compounds containing the residue of an acetoacetate or betadiketone as the organic oxy group are especially preferred.

The valence of zirconium is 4 and a coordination number of 8. Thus, the organic zirconium compounds include not only the aforesaid zirconium tetra-alcoholates, but also other organic zirconium compounds meeting the above-specified require ment for the valence and/or coordination number, such as zirconium tetraacetyl acetonate.

Especially preferred organic metal compounds in the first to third groups described hereinabove are those of formula (I) which contain in the molecule at least one organic oxy group containing a carbonyl group derived from a beta-dicarbonyl compound or beta-hydroxycarbonyl compound, and which are obtained by reacting one mole of metal alcoholate compounds of formula (I) in which OR', OR2, OR3 and OR4 are alkoxy or alkenyloxy groups with not more than 4 moles of a beta-dicarbonyl compound or beta-hydroxy compound.

The organic titanium compounds of the second group have better storage stability than the organic aluminum compounds of the first group, and when the organic zirconium compounds of the third group are used, yellowing of coated films which may occur with the use of organic titanium compounds is not at all observed.

Curing of the vinyl polymer containing an acetoacetate group in accordance with this invention is carried out by reacting the vinyl polymer with the organic metal compound of formula (I).

The suitable proportions of the vinyl polymer and the organic metal compounds are difficult to determine definitely because they differ according to the concentration of the acetoacetate group contained in the vinyl polymer and the type of the organic metal compound used. Generally, the organic metal compound is used in an amount of 1 to 50% by weight, preferably 1 to 20% by weight, based on the weight of the vinyl polymer containing an acetylacetonate group. When the organic metal compound is an organic aluminum compound, its amount is generally 1 to 50 /O by weight, especially preferally 2 to 20% by weight. When the organic metal compound is an organic titanium compound, its amount is generally 0.5 to 50% by weight, preferably 1 to 20% by weight.

When it is an organic zirconium compound, its amount is generally 0.1 to 50% by weight, preferably 1 to 20% by weight.

The curing reaction in accordance with this invention sufficiently proceeds even at room temperature, and gives a coated film having superiortransparency, ultraviolet light resistance, chemical resistance, solvent resistance and physical properties.

Thus, the method of curing in accordance with this invention is characterized by the fact that it proceeds sufficiently even at room temperature to give a coated film having the superior properties as described above. This, however, does not preclude the performance of the curing reaction at a higher temperature. For example, the curing reaction proceeds at a temperature of 40 to 200"C.

The details of the curing reaction in accordance with this invention are not entirely clear. It is presumed however that the acetoacetate group of the vinyl polymer exchanges ligands with the alkoxy, alkenyloxy or organic oxy group of the organic metal compound to form a structure in which the acetoacetate group of the vinyl polymer is coordinated with the metal.

As stated hereinabove, the vinyl polymer in this invention may have a hydroxyl or carboxyl group in addition to the acetoacetate group. Investigations of the present inventors have shown that when the vinyl polymer additionally has a hydroxyl group, it forms an alkoxide linkage together with the organic metal compound, and that when it additionally has a carboxyl group, it forms a carboxylate linkage together with the organic metal compound.

Judging from the fact that the curing reaction of this invention proceeds sufficiently at room temperature even on a vinyl polymer containing an acetoacetate group but free from a hydroxyl or carboxyl group, the curing reaction in accordance with this invention essentially differs from curing based Qn the reaction of the organic metal compound with a hydroxyl or carboxyl group.

Accordingly, the present invention provides use of the organic metal compound of formula (I) as a curing ingredient for a vinyl polymer containing an acetoacetate group in the molecule.

In performing the curing reaction in accordance with this invention, the vinyl polymer containing an acetoacetate group is mixed with the organic metal compound. However, investigations of the present inventors have shown that under certain conditions, curing reaction is not started even when the vinyl polymer containing an acetoacetate group is contacted with the organic metal compound, and therefore, it is possible to provide a solution of a composition having good storage stability which comprises both the vinyl polymer and the organic metal compound.

Thus, the present invention also provides a solution of a composition of a vinyl polymer having good storage stability, said solution comprising a vinyl polymer containing an acetoacetate group in the molecule and an organic solvent for said polymer, said solution further comprising an organic metal compound of formula (I), and said solvent being a mixed solvent containing an aliphatic alcohol.

The organic solvent constituting one ingredient of the solution of the vinyl polymer composition is an organic solvent capable of dissolving the organic metal compound and the vinyl polymer containing an acetoacetate group in the molecule, and is prefer ably highly volatile at room temperature and atmos pheric pressure.

Examples of the organic solvent includes aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene and trimethylbenzene, aliphatic hyd rocarbons such as petroleum ether, n-hexane, hep tane, octane, nonane, decane, undecane, dodecane, cyclohexane, methylcyclohexane, 1,1dimethylcyclohexane, and ethylcyclohexane, aliphatic carboxylic acid esters such as n-butyl acetate, methyl acetate, amyl acetate, methylamyl acetate, Cellosolve acetate, 2-ethylhexyl acetate and cyclohexyl acetate, aromatic carboxylic acid esters such as methyl benzoate; and Cellosolve acetate (CH3COOC2H4OC2Hs), carbitol acetate (CH3COOCH2CH(C2H5)CH4H9) and methyl Cellosolve acetate (CH3COOCH2CH3OCH3).

The solution in accordance with this invention further contains an aliphatic alcohol. The aliphatic alcohol inhibits a curing reaction between the vinyl polymer containing an acetoacetate group and the organic metal compound within the solution of this invention containing both.

Suitable aliphatic alcohols include aliphatic alcohols having 1 to 8 carbon atoms, especially 1 to 5 carbon atoms, and mono-lower aliphatic alkyl ethers of ethylene glycol or diethylene glycol in which the lower aliphatic alkyl group has 1 to 4 carbon atoms, for example. Specific examples of lower aliphatic alcohols are methanol, ethanol, n-propanol, isopropanol and n-butanol. Specific examples of the mono-lower aliphatic alkyl ethers are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether.

Preferably, the solution of the composition in accordance with this invention consists basically of 10 to 80% by weight of the vinyl polymer containing an acetoacetate group, 0.1 to 40% by weight of an organic metal compound, 5 to 80% by weight of the organic solvent, and 10 to 65% by weight of the aliphatic alcohol. If desired, the solution of this invention may further contain various additives.

Examples of such additives are pigments such as titanium oxide, flowers of zinc (ZnO), red iron oxide (Fe2O3), carbon black, lead chromate, iron black, strontiumchromate, zinc chromate and basic lead sulfate; fillers or extender pigments such as talc, calcium carbonate (CaCO3), baryta (BaSO4), clay, mica, finely divided silica, and glass fibers; and dyes such as indigo, thionine, Rhodamine, prussian blue and Astra-Phloxine.

Such an additive may be used in an amount of 1 to 300 parts by weight per 100 parts by weight of the basic composition of the solution of this invention.

When the solution of this invention is formed into a thin coated film and the solvent including the aliphatic alcohol is evaporated, curing reaction in accordance with the method of this invention takes place to give a cured film having the superior properties described hereinabove.

Formation of the coated film can be effected by known methods such as brush coating, roller coating, curtain flow coating, or spray coating.

The curing reaction in accordance with this invention proceeds sufficiently at room temperature, and therefore, the solvent including the alcohol used in the solution of this invention should better be those which can be evaporated at ordinary temperatures.

When the solvent and/or alcohol is difficult to evaporate atordinarytemperatures, and a comparatively long period of time is required for the dying of the coated film, the coating may be heated to a suitable temperature.

The following Examples are given to facilitate the understanding of this invention without any intention of limiting the invention thereto.

All parts in these Examples are by weight. The gel contents of the cured coatings described in these Examples were measured in the following manner.

A solution containing the vinyl polymer having an acetoacetate group and the organic metal compound is coated on a glass plate, and allowed to stand for a predetermined period of time in an atmosphere kept at 250C and a relative humidity of 65%. A part (about 1 g) of the resulting dried and cured coating is peeled off from the glass plate, and divided into rectangular pieces.

The rectangular pieces are enveloped with a 200-mesh wire gauze, and dipped for8 hours in a boiling mixture of acetone isopropyl alcohol (1:1 by weight) to extract the soluble portion. The extraction residue is dried at 105"C for 3 hours.

The gel content of the cured coating is calculated in accordance with the following equation.

Gel content (%) = (B+W)-W ~ Ww x 100 (A+W)-W A: the total amount of the coating before extraction B: the total amount of the coating after extraction W: the weight of the wire gauze According to this invention, it has been made clear that a cured coated film having a gel content of as much as 100% can be obtained.

Example 1 (1) A 500 ml four-necked round-bottomed flask equipped with a thermometer, a stirrer, a condenser and a dropping funnel was charged with 50 g of toluene and 50 g of n-butyl acetate, and the air inside the flask was replaced by nitrogen gas. The mixture was heated to 100"C, and when the temperature became constant, a mixture consisting of 30 g of styrene, 20 g of methyl methacrylate, 30 g of butyl acrylate, 20 g of 2-hydroxyethyl methacrylate and 1 g of azobisisobutyronitrile as a polymerization initiator was added dropwise over the course of 2 hours. I n 5 hours after the addition, the conversion reached nearly 100%. A colorless clear resin solution was obtained which had a viscosity (measured at 25"C by a Gardnerviscometer) of Y and a involatile content of 50%.The resin solution is referred to as a resin solution (1).

(2) Two hundred grams of the resin solution (1) was taken into the above reactor, and heated to 50 to 60"C. When the temperature became constant, the reactor was charged with 12.9 g of diketene, 0.05 g of anhydrous sodium acetate and 12.9 g of methyl ethyl ketone. Ten hours after the addition, the infrared spectrum of the reaction mixture was measured, and consequently, it was ascertained that the reaction was terminated. A pale reddish brown clear resin solution was obtained which had an involatile content of 50% and a viscosity of X. The resulting solution of a resin having an acetoacetate group is referred to as a resin solution (2).

(3) To 100 g of the resin solution (2) was added 5 g of a curing agent obtained by mixing 100 g of aluminum tri-sec-butoxide and 130 g of acetylacetone (referred to as a curing agent (1)). The resulting solution had a viscosity of Z, and was found to be very stable without any rise in viscosity in a storage stability test conducted at 50"C for 7 days.

The solution was coated on a glass plate so that the coating after drying had a thickness of 20 to 30 microns, and allowed to stand in a room kept at 25"C and a relative humidity of 65"C. Twenty-four hours later, the gel content of the coated film was measured. The result is shown in Table 1. Rutile titanium oxide was added to the solution in an amount of 40 parts per 50 parts of the involatile component of the solution. The mixture was kneaded with a three-roll mill to form a white enamel. The white enamel was diluted to a suitable viscosity, and spray-coated on a phosphate-treated steel plate and dried at 20"C for 24 hours. The properties of the resulting coated film are shown in Table 2.

Example 2 One hundred grams of the resin solution (1) produced in Example 1 was mixed with 100 g of aluminum triisopropoxide and 190 g of ethyl acetoacetate. Then, 10 g of a curing agent was added to form a solution of a resin composition. The solution had a viscosity of Z, and had superior storage stability the same as the resin solution of Example 1.

A coated film was prepared from the solution in the same way as in Example 1, and its gel content was measured. Furthermore, in the same way as in Example 1, a white enamel was produced, and the properties of a coated film prepared from it were examined. The results are shown in Tables 1 and 2.

Example 3 (1) The same reactor as used in Example 1 was charged with 100 g of 2-hydroxyethyl acrylate, and heated to 60 to 70"C. When the temperature became constant, 0.1 g of anhydrous sodium acetate was added, and then diketene was added dropwise over the course of 2 hours. Sufficient care was taken because there was vigorous generation of heat. The infrared spectrum of the reaction mixture taken after 2 hours from the addition showed that the reaction was terminated.

The resulting monomer is referred to as a monomer (1).

(2) The same four-necked flask as used in Example 1,(1)was charged with 50 g of xylene and 50 9 of butyl acetate, and the mixture was heated to 1000C.

When the temperature became constant, a mixture consisting of 20 g of styrene, 20 g of methyl methacrylate, 50 g of n-butyl methacrylate, 30 g of the monomer (1) and 0.5 g of lauryl peroxide as a polymerization initiator was added dropwise over the course of 3 hours. Six hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution was obtained which had a viscosity of Z-2 and an involatile content of 50%. The solution is referred to as a resin solution (3).

(3) To 100 g of the resin solution (3) were added 3 g of aluminum tri-sec-butoxide and 20 g of isopropyl alcohol to afford a resin solution having a viscosity of W and an involatile content of 41%. The gel content and the properties of a coated film prepared from a white enamel were determined with regard to the resulting solution in the same way as in Example 1. The results are shown in Tables 1 and 2.

Example 4 (1) The same four-necked flask as used in Example 1, (1 ) was charged with 50 g ofxylene and 50 g of butyl acetate. The mixture was heated to 100 C, and when the temperature became constant, a mixture consisting of 20 g of styrene, 20 g of ethyl methacrylate, 38 g of butyl acrylate, 2 g of methacrylic acid, 20 g of the monomer (1 ) and 0.5 g of tert-butyl peroxybenzoate as a polymerization initiator was added dropwise over the course of3 hours. In 6 hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution having a viscosity of Z-3 and an involatile content of 50% was obtained.

The resin solution is referred to as a resin solution (4).

(2) Ten grams of the curing agent (1 ) of Example 1 was added to 100 g of the resin solution (4). The resulting resin solution had a viscosity of Z-3.

(3) The gel content and the properties of a white enamel were examined in the same way as in Exam ple 1 using the resulting resin solution. The results are shown in Tables 1 and 2.

Comparative Example 1 Five grams of the curing agent (1 ) of Example 1 was added to 100 g of the hydroxyl-containing resin solution (1) obtained in Example 1, (1). The resulting resin composition had a viscosity of Z-1. It was stable without any rise in viscosity in a storage stability test conducted at 500C for 7 days. The gel content measured in the same way as in Example 1 was 40% which was much lower than the gel content (70%) in Example 1. The properties of a white enamel are shown in Table 2. The coated film was found to be inferior in solvent resistance to those obtained in the Examples.

Table 1

Comparative Example 1 Example2 Example3 Example4 Example 1 Gel content (%) 70 95 80 95 40 Table2

Comparative Example 1 Example2 Example3 Example4 Example 1 Hardness (1) H 2H 2H 2H F Erichsen test 6 mm 6 mm 7 mm 5 mm 5 mm Crosscut adhesion test 100/100 100/100 100/100 90/100 80/100 Du Pont impact test (500 1/2 inch) 50 cm 40 cm 40 cm 40 cm 30 cm Acid resistance (2) Good Good Good Good Slightly poor Alkali resistance (3) Good Good Good Good Good Solvent resistance (4) Good Good Good Good Poor (1) Pencil hardness (2) The state of the coating after dipping for 7 hours in a 5% aqueous solution of sulfuric acid.

(3) The state of the coating after dipping for 7 hours in a 3% aqueous solution of sodium hydroxide.

(4) The coated film is wiped with a gauze impregnated with a 1:1 mixture of xylene and n-butyl alcohol through 20 reciprocations, and then the solvent resistance of the surface of the coated film is evaluated by the state of injury and swelling.

Example 5 (1 ) A 500 ml four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping funnel was charged with 50 g of toluene and 50 g of n-butyl acetate. The air inside the flask was replaced by nitrogen gas, and the contents were heated to 100"C. When the temperature became constant, a mixture consisting of 30 g of styrene, 20 g of methyl methacrylate,30 g of butyl acrylate, 20 g of 2-hydroxyethyl methacrylate and 1 g of azobisisobutyronitrile as a polymerization initiator was added dropwise over the course of 2 hours. In 5 hours after the addition, the conversion reached nearly 100%. A colorless transparent resin solution was obtained which had a viscosity of Y and an involatile content of 50%. The solution is referred to as a resin solution (5).

(2) Then, 200 g of the resin solution (5) was taken into the above reactor, and heated to 50 to 60"C when the temperature became constant, 12.9 g of diketene,0.05 g of sodium acetate and 12.9 g of methyl ethyl ketone were added. The infrared spectrum of the reaction mixture taken 10 hours after the addition showed that the reaction was terminated.

At this point, a pale reddish brown clear resin solution having a viscosity of X and an involatile content of 50% was obtained. This solution having an acetoacetate group is referred to as a resin solution (6).

(3) To 100 g of the resin solution (6) was added 5 g of a curing agent obtained by mixing 340 g of tetran-butyl titanate with 200 g of acetylacetone (to be referred to as a curing agent (2)). The resulting solution had a viscosity of Y-Z and was very stable without any rise in viscosity in a storage stability test conducted at 50"C for 7 days.

(4) The resulting solution was coated on a glass plate so that the thickness of the coating after drying would be 20 to 30 microns, and allowed to stand in a room kept at 250C and a relative humidity of 65% to form a cured coating. Twenty-four hours later, the gel content of the cured coating was measured, The results are shown in Table 3.

Rutile titanium oxide was mixed with the aforesaid solution in an amount of 40 9 per 50 g of the involatile component of the solution, and the mixture was kneaded by a three-roll mill to form a white enamel. The white enamel was diluted to a suitable viscosity, sprayed onto a phosphate-treated steel plate, and dried at 200C for 24 hours. The properties of the resulting coating are shown in Table 4.

Example 6 To 100 g of the resin solution (6) obtained in Example 5 was added 10 g of a curing agent obtained by mixing 284 g of tetra-isopropyl titanate and 232 g of methyl acetoacetate. The resulting resin solution had a viscosity of Z, and exhibited superior storage stability the same as the solution obtained in Example 5. In the same way as in Example 5, the gel content and the properties of a white enamel were examined in regard to this resin solution. The results are shown in Tables 3, and 4 respectively.

Example 7 (1 ) one hundred grams of 2-hydroxyethyl acrylate was placed in the same reactor as used in Example 6, and heated to 60 to 700C. When the temperature became constant, 0.1 g of anhydrous sodium acetate was added, and subsequently, diketene was added dropwise over the course of 2 hours. (Utmost care was needed because there was vigorous generation of heat.) The infrared absorption spectrum of the reaction mixture taken two hours after the addition showed that the reaction was terminated. The monomer obtained bythis reaction is referred to as a monomer (2).

(2) The same reactor as used in Example 5 was charged with 50 g of xylene and 50 g of n-butyl acetate, and they were heated to 1000C. When the temperature became constant, a mixture consisting of 20 g of styrene, 20 g of methyl methacrylate, 30 g of n-butyl methacrylate, 30 g of the monomer (2) and 0.5 g of lauryl peroxide as a polymerization initiator was added dropwise over the course of 3 hours. In 6 hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution was obtained which had a viscosity of Z-2 and an involatile content of 50%. The solution is referred to as a resin solution (7).

(3) To 100 g of the resin solution (7) was added 5 g of a decamer of tetra-n-butyl titanate and 20 g of isopropyl alcohol to form a solution having a viscosity of X and an involatile content of 42%. The gel content and the properties of a white enamel were examined in the same way as in Example 1 with regard to the solution. The results are shown in Tables 3 and 4, respectively.

Example 8 (1) The same reactor as used in Example 5 was charged with 50 g of xylene and 50 g of n-butyl acetate, and they were heated to 100"C. When the temperature became constant, a mixture consisting of 20 g of styrene, 30 g of ethyl methacrylate, 40 g of butyl acrylate, 10 g of the monomer (2) and 0.5 g of tertiary butyl peroxy-benzoate was added dropwise over the course of 3 hours. In 6 hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution having a viscosity of Z4 was obtained.

The solution is referred to as a resin solution (8).

(2) To 100 g of the resin solution (8) was added 10 g of a curing agent obtained by mixing 970 g of a tetramer of tetra-n-butyl titanate, 400 g of acetylacetone and 930 g of diacetone alcohol. The resulting resin composition solution had a viscosity of Z4. The gel content of the resin composition was measured in the same way as in Example 5, and the properties of a white enamel prepared from the resin composition were also examined in the same way as in Example 5. The results are shown in Tables 3 and 4, respectively.

Comparative Example 2 Five grams of the curing agent (2) used in Example 5 was added to 100 g of the resin solution obtained in Example 5. The resulting resin composition had a viscosity of Z-1, and was stable without any rise in viscosity in a storage stability test conducted at 50"C for7 days. The gel content measured in the same way as in Example 5 was 45% which was much lower than that (75%) in Example 5. The properties of a white enamel prepared from the resin composition are shown in Table 4. It is seen that the solvent resistance of the white enamel was inferior to those in the Examples.

Table3

Comparative Example 5 Example 6 Example7 Example 8 Example 3 Gel content (%) 75 92 83 94 45 Table4

Comparative Example 5 Example 6 Example 7 Example8 Example 3 Hardness (1) H 2H 2H 2H HB Erichsene test 6 mm 7 mm 7 mm 6 mm 5 mm Crosscut adhesion test 100/100 100/100 100/100 100/100 80/100 Du Pont impact test (500 g, 1/2 inch) 40 cm 40 cm 40 cm 50 cm 30 cm Acid resistance (2) Good Good Good Good Slightly poor Alkali resistance (3) Good Good Good Good Good Solvent resistance (4) Good Good Good Good Poor Storage stability (5) Good Good Good Good Good (Note): (1), (2), (3), and (4) are the same as the foot notes to Table 2. (5): The degree of viscosity increase after storage for 7 days at 50"C.

Example 9 (1 ) A 500 ml. four-necked flask equipped with a thermometer, a stirrer, a condenser and a dropping funnel was charged with 50 g of toluene and 50 g of n-butyl acetate. The air inside the flask was replaced by nitrogen gas, and the contents were heated to 100"C. When the temperature became constant, a mixture consisting of 30 g of styrene, 20 g of methyl methacrylate, 30 g of butyl actylate, 20 g of 2-hydroxyethyl methacrylate and 1 g of azobisiobutyronitrile as a polymerization initiator was added dropwise over the course of 2 hours. In 5 hours after the addition, the conversion reached nearly 100%. A colorless clear resin solution having a viscosity of Y and an involatile content of 50% was obtained. This solution is referred to as a resin solution (9).

(2) Two hundred grams of the resin solution (9) was taken into the above reactor, and heated to 50 to 60"C. When the temperature became almost constant, 12.9 g of diketene, 0.05 g of anhydrous sodium acetate and 12.9 g of methyl ethylketone were added to the reactor. The infrared absorption spectrum of the reaction mixture taken 10 hours after the addition showed that the reaction was terminated. At this point, a pale reddish brown clear resin solution was obtained which had an involatile content of 50% and a viscosity of X. The resulting solution of the resin containing an acetoacetate group is referred to as a resin solution (10).

(3) To 100 g of the resin solution (10) was added 5 g of a curing agent obtained by mixing 953 g of tetra-n-butyl zirconate (3.4-mer) and 1020 g of acetylacetone (a colorless crystalline powder; refer red to as a curing agent (3)). The resulting resin solution had a viscosity of Y, and was very stable without any rise in viscosity in a storage stability test con ducted at50 Cfor7 days.

(4) The composition was coated on a glass plate so that the thickness of the coating after drying became 20 to 30 microns, and allowed to stand in a room kept at 25"C and a relative humidity of 65%. The gel content was measured 24 hours later. The results are shown in Table 5.

Rutile titanium oxide was mixed with the composi tion in an amountof40 g per 50 g ofthe involatile component of the composition. The mixture was kneaded on a three-roll mill to form a white enamel.

The white enamel was diluted to a suitable viscosity, sprayed on a phosphate-treated steel sheet, and dried at 20 C for 24 hours. The properties of the resulting coated film are shown in Table 6.

Example 10 To 100 g of the resin solution (9) obtained in Example 9 was added 10 g of a curing agent obtained by mixing 745 g of a trimer of tetraisopropyl zirconate and 700 g of methyl acetoacetate.

The resulting resin composition solution had a viscosity of Z and exhibited superior storage stability the same as in the composition of Example 9. The gel content and the properties of a white enamel were examined with regard to this composition in the same way as in Example 9. The results are shown in Tables 5 and 6, respectively.

Example 11 (1) One hundred grams of 2-hydroxyethyl acrylate was placed in the same reactor as used in Example 9, and heated to 60 to 700C. When the temperature became constant,0.1 g of anhydrous sodium acetate was added, and subsequently, diketene was added dropwise over the course of 2 hours. (Utmost care was required because there was vigorous generation of heat.). The infrared absorption spectrum of the reaction mixture taken 2 hours after the addition showed that the reaction was terminated. The resulting monomer is referred to as a monomer (3).

(2) The same reactor as used in Example 9 was charged with 50 g of xylene and 50 g of n-butyl acetate, and they were heated to 1000C. When the temperature became constant, a mixture consisting of 20 g of styrene, 20 g of methyl methacrylate, 30 g of n-butyl methacrylate,30 g of the monomer (3) and 0.5 g of lauryl peroxide as a polymerization initiator was added dropwise over the course of 3 hours. In 6 hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution was obtained which had a viscosity of Z-2 and an involatile content of 50%. This solution is referred to as a resin solution (10).

(3) To 100 g of the resin solution (10) were added 5 g of tetra-n-butyl zirconate (3.4-mer) and 20 g of isopropyl alcohol to form a resin composition solution having a viscosity of W to X and an involatile content of 41%. The gel content and the properties of a white enamel were examined on this composition solution in the same way as in Example 9. The results are shown in Tables 5 and 6, respectively.

Example 12 (1) The same reactor as used in Example 9 was charged with 50 g of xylene and 50 g of n-butyl acetate, and they were heated to 1000C. When the temperature became constant, a mixture consisting of 20 g of styrene, 30 g of ethyl methacrylate, 40 g of butyl acrylate, 10 g of the monomer (3) and 0.5 g of tertiary butyl peroxybenzoate as a polymerization initiator was added dropwise over the course of3 hours. In 6 hours after the addition, the conversion reached nearly 100%. A pale yellow clear resin solution was obtained which had a viscosity of Z-4. This resin solution is referred to as a resin solution (12).

(2) To 100 g of the resin solution (12) was added 10 g of a curing agent obtained by mixing 953 g of tetra-n-butyl zirconate (3.4-mer), 340 g of acetylacetone and 442 g of ethyl acetoacetate. The resulting resin composition had a viscosity of Z-3.

The gel content and the properties of a white enamel were measured on this resin solution in the same way as in Example 9. The results are shown in Tables 5 and 6.

Comparative Example 3 To 100 g of the resin solution (9) obtained in Example 9 was added 5 g of the curing agent (3) obtained in Example 9. The resulting resin composition solution had a viscosity of Z-1, and was stable without any rise in viscosity in a storage stability test conducted at 500C for 7 days. The gel content measured in the same way as in Example 9 was 40%, which was much lower than that (72%) in Example 9.

The properties of a white enamel prepared from the resulting resin composition solution are shown in Table 6. It was found that the solvent resistance of the white enamel coating was inferior to those in the Examples.

Example 5

Comparative Example9 Example 10 Example 11 Example 12 Example3 Gel content (%) 72 89 85 92 40 Example 6

Comparative Example9 Example 10 Example 11 Example 12 Example3 Hardness (1) H 2H 2H 2H HB Erichsen test 6 mm 6 mm 7 mm 7 mm 5 mm Crosscut adhesion test 1001100 100/100 100/100 1001100 801100 Du Pont impact test (500 g, 112 inch) 40 cm 50 cm 50 cm 40 cm 30 cm Acid resistance (2) Good Good Good Good Slightly poor Alkali resistance (3) Good Good Good Good Good Solvent resistance (4) Good Good Good Good Poor Storage stability (5) Good Good Good Good Good (Note): (1) to (5) are the same as the footnotes to Table 4.

Claims (11)

1. A method for curing a vinyl polymer containing an acetoacetate group in the molecule, which comprises reacting the vinyl polymer with an organic metal compound of the formula

wherein M is Al, Ti or Zr; OR1, OR2, OR3 and OR4 are the same or different, and each represents an alkoxy group, an alkenyloxy group, or an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound, or any two of OR1, OR2, OR3 and OR4 together form an alkylenedioxy group; n is a number of from 0 to 10; and m is a number determined by the atomic valence and/or coordination number of M,andOor1.

2. A method according to claim 1 wherein the organic metal compound is of the formula

wherein all symbols are as defined in claim 1.

3. A method according to claim 1 wherein the organic metal compound is of the formula

wherein all symbols are as defined in claim 1.

4. A method according to claim 3 wherein the organic metal compound is of the formula

wherein OR11, OR21, OR3' and OR4' each represent an alkoxy group of 1 to 20 carbon atoms, an alkenyloxy group of 2 to 20 carbon atoms, or an organic oxy group containing a carbonyl group which is the residue of a beta-dicarbonyl compound or betahydroxycarbonyl compound, and m and n are as defined in claim 1.

5. A method according to claim 1 wherein the organic compound is of the formula

wherein all symbols are as defined in claim 1.

6. A method according to claim 5 wherein the organic metal compound is of the formula

wherein p represents a number of from 0 to 5, and all other symbols are as defined in claim 5.

7. A method according to any one of claims 1 to 6 wherein the organic metal compound contains in the molecule at least one organic oxy group containing a carbonyl group which is the residue of a betadicarbonyl compound or beta-hydroxycarbonyl compound, said compound being obtained by reacting 1 mole of a metal alcoholate compound of formula (I) in which OR', OR2, OR3 and OR4 each represent an alkoxy or alkenyloxy group with not more than 4 moles of a beta-dicarbonyl compound or beta-hydroxycarbonyl compound.

8. A method according to claim 1 substantially as described in any one of the Examples.

9. A storage stable solution comprising a vinyl polymer containing an acetoacetate group in the molecule, an organic solvent for said vinyl polymer comprising an aliphatic alcohol, and an organic metal compound as defined in any one of claims 1 to 7.

10. A solution according to claim 9 wherein said vinyl polymer containing an acetoacetate group in the molecule is the reaction product between a vinyl polymer having a hydroxyl group in the molecule and diketene.

11. Use of an organic metal compound of formula (I) as defined in claim 1 as a curing ingredient for a vinyl polymer containing an acetoacetate group in the molecule.