Resin compositions and a method of curing the same

Abstract: The invention provides the following resin composi­ tions. 1. A composition comprising (A), (B), (C) and (D); 2. a composition comprising (A), (E) and (D); 3. a composition comprising (F), (G) and (D); and 4. a composition comprising (H), (C) and (D). where (A) a high molecular weight hydroxy compound con­ taining an average of 2 or more hydroxyl groups per molecule and having a number average molecular weight of 3,000. to 200,000; (B) an epoxy compound containing an average of 2 or more epoxy groups per molecule and having a number average molecular weight of 120 to 200,000, (C) a silane compound containing an average of 1 or more alkoxysilane, silanol and/or acyloxysilane groups per molecule and having a number average molecular weight of 104 to 200,000, (D) at least one chelate compound of aluminum, titanium or zirconium, (E) a high molecular weight compound containing an average of 2 or more epoxy groups and an average of 1 or more alkoxysilane, silanol and/or acyloxysilane grcups per molecule and having a number average molecular weight compound containing an average of 2 or more hydroxyl groups and an average of 1 or more alkoxysilane, silanol and/or acyloxysilane groups per molecule and having a number average molecular weight of 3,000 to 200,000; (G) a low molecular weight compound containing an average of 2 or more epcxy groups per molecule and having a number average molecular weight of 240 to 5,000; and (H) a high molecular weight compound containing an average of 2 or more hydroxyl groups and an average of 2 or more epoxy groups per molecule and having a number average molecular weight of 3,000 to 200,000. A method of curing these compositions at a tempera­ ture not exceeding 100°C is also described.

Description: The present invention relates to novel resin compositions and a method of curing the same. For the curing of resins containing hydroxyl groups as functional groups, methods employing diisocyanate compounds or melamine resin have heretofore been employed. However, with diisocyanates, the resulting films are generally inadequate in weather resistance and tend to undergo yellowing. Furthermore, the resin compositions have short pot lives, not to speak of the toxicity problem associated with diisocyanates. When a melamine resin is employed, a high baking temperature over about 140°C is necessary and the resulting film is not as resistant to acid as desired. JP-A- 56/160054 discloses a cured epoxy resin composition containing an epoxy resin, a silicone resin, a phenol novolak resin, an organo-aluminum compound such as aluminum acetylacetonate and a non-alkaline inorganic filler as corrosion resistant encapsulant for a semiconductor device. JP-A- 58/160342 describes a resin composition which can be rapidly cured and is obtained by incorporating an Al complex such as tris(ethylaceto acetato) aluminum and a certain silanol group containing polymer as curing catalysts in an epoxy resin. It is an object of the present invention to provide novel hydroxyl group-containing resin compositions which are curable at a sufficiently high rate at a low temperature not exceeding 100°C and a method of curing the same compositions. It is another object of the invention to provide novel hydroxyl group-containing resin compositions which not only have good curability at low temperature but are also adapted to yield a cured film having excellent weather resistance, acid resistance and other physical properties and a method of curing the same compositions. Other objects and advantages of the present invention will become apparent as the following description of the invention proceeds. The present invention provides novel resin compositions and a method for curing the same, said resin compositions comprising (A) 5 to 95 weight percent of a high molecular weight hydroxy compound containing an average of 2 or more hydroxyl groups bonded to aliphatic carbon atoms per molecule and having a number average molecular weight of 3,000 to 200,000, (B) 95 to 5 weight percent of an epoxy compound containing an average of 2 or more epoxy groups per molecule and having a number average molecular weight of 120 to 200,000, (C) 0.1 to 50 parts by weight per 100 parts by weight of (A) and (B) combined of a silane compound containing an average of 1 or more functional groups selected from alkoxysilane, silanol and acyloxysilane groups per molecule and having a number average molecular weight of 104 to 200,000, and (D) 0.01 to 10 parts by weight per 100 parts by weight of (A) and (B) combined of at least one metal chelate compound of aluminum, titanium or zirconium which contains a compound showing keto-enol tautomerism as a ligand. The present invention also provides a method of curing a resin composition which comprises crosslinking the above resin compositions at a temperature not exceeding 100°C. To overcome the aforementioned disadvantages of the prior art technologies, the inventor of the present invention carried out studies for developing a hydroxyl group-containing resin composition which is curable at low temperature to yield satisfactory film properties. As a result, it was found that a high molecular weight compound containing two or more hydroxyl groups per molecule may be caused to cure at a sufficiently high rate even at a low temperature not exceeding 100°C when it is so arranged that the curing reaction may take place in the presence of functional groups of at least one selected from the class consisting of alkoxysilane, silanol and acyloxysilane groups as well as epoxy groups with the aid of, as a curing catalyst, at least one metal chelate compound selected from the above aluminum chelate compounds, titanium chelate compounds and zirconium chelate compounds and that the resulting cured film has excellent weather resistance, acid resistance and other physical properties. The present invention is predicated on the above findings. The high molecular weight hydroxy compound (A) is a compound containing an average of two or more hydroxyl groups bonded to aliphatic carbon atoms per molecule and has a number average molecular weight of 3,000 to 200,000, preferably 5,000 to 80,000. If the number of hydroxyl groups bonded to aliphatic carbon atoms is less than 2 on the average per molecule, the curing performance and the gel fraction ratio of the film will be decreased. From the standpoint of weatherability and water resistance, the number of hydroxyl groups is preferably not more than 400 on the average per molecule. If the number average molecular weight of compound (A) is less than 3,000, the impact resistance, weatherability and other physical properties will not be as good as desired. On the other hand, if the number average molecular weight exceeds 200,000, the compatibility of the compound with the other components will be poor so that the uniformity of cure will be sacrificed to detract from the weather resistance of the cured film. As examples of the high molecular weight hydroxy compound (A), compounds in the following categories (1) through (6) can be mentioned. (1) High molecular weight acrylic polyol compounds: Homopolymers of hydroxyl group-containing vinyl monomers (I) (for example, hydroxy-C 2-8 alkyl esters of (meth)acrylic acid such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate, and adducts of such hydroxy-C 2-8 alkyl esters of (meth)acrylic acid with lactones such as ε-caprolactone, γ-valerolactone) and copolymers of said hydroxyl group-containing vinyl monomers (I) with other α,β-ethylenically unsaturated monomers (II). Examples of said α,β-ethylenically unsaturated monomers (II) include: (a) Esters of acrylic acid or methacrylic acid: C 1-18 alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate; C 2-18 alkoxyalkyl esters such as methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate; C 2-8 alkenyl esters such as allyl acrylate, allyl methacrylate; C 3-18 alkenyloxyalkyl esters such as allyloxyethyl acrylate, allyloxyethyl methacrylate. (b) Vinyl-aromatic compounds: styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene. (c) Polyolefin compounds: butadiene, isoprene, chloroprene. (d) Others: acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, VeoVa monomers (Shell Chemical), vinyl propionate, vinyl pivalate, acrylic acid, methacrylic acid. (2) High molecular weight polyester polyol compounds: The compounds obtainable by esterifying polybasic acids (compounds containing 2 to 4 carboxyl groups per molecule, such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, pyromellitic acid and the corresponding anhydrides) with polyhydric alcohols (alcohols containing 2 to 6 hydroxy groups in the molecule, such as ethylene glycol, polyethylene glycol, propylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, glycerol, tricyclodecanedimethanol. Aside from the above compounds, monobasic acids (for example, fatty acids such as caster oil fatty acid, soybean oil fatty acid, tall oil fatty acid, linseed oil fatty acid, benzoic acid) can also be used if necessary. (3) High molecular weight fluorine-containing polyol compounds: Copolymers of fluorine-containing (meth)acrylate monomers (III) (for example, perfluorooctylethyl (meth)acrylate, perfluoroisononylethyl (meth)acrylate) with monomers (I); copolymers of monomers (I), (II) and (III); copolymers of fluorine-containing ethylene monomers with vinyl ethers (for example, copolymer of monochlorotrifluoroethylene, alkylvinyl ether and hydroxyalkylvinyl ether [Lumiflon®, trademark of Asahi Glass Co., Ltd.]) (4) High molecular weight polyurethane polyol compounds: Isocyanate-free polymers obtainable by modifying said high molecular weight acrylic polyol compounds, polyester polyol compounds with polyisocyanates (for example, tolylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate). (5) High molecular weight silicone polyol compounds: Alkoxysilane-, acyloxysilane- or silanol-free polymers obtainable by modifying said high molecular weight acrylic polyol compounds, polyester polyol compounds with silicone resins (for example, Z-6018 and Z-6188 [both are products of Dow Corning], SH5050, SH6018 and SH6188 [all are products of Toray Silicone]) (6) Vinyl alcohol-styrene copolymers. The epoxy compound (B) mentioned hereinbefore contains an average of 2 or more epoxy groups per molecule and has a number average molecular weight of 120 to 200,00, preferably 240 to 80,000. If the number of epoxy groups is less than 2, the curing performance and gel fraction ratio will be decreased. From the standpoint of curing performance, the average number of epoxy groups is preferably not more than 500 per molecule. Epoxy compounds with number average molecular weights less than 120 are hardly available. On the other hand, if the number average molecular weight exceeds 200,000, the compatibility of the compound with the other components is poor so that the weatherbility of the cured film is sacrified. From the standpoint of curing performance, the epoxy compound (B) preferably has alicyclic epoxy groups. As specific examples of the epoxy compound (B), the following compounds can be mentioned. adducts of with polyisocyanate compounds (i.e. organic diisocyanates such as aliphatic diisocyanates, e.g. hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, alicyclic diisocyanates, e.g. hydrogenated xylylene diisocyanate, isophorone diisocyanate, and aromatic diisocyanates, e.g. tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, adducts of such organic diisocyanates with polyalcohols, low molecular weight polyesters, water or the like, polymers of said respective organic diisocyanates, and isocyanate biurets; representative commercial products of these compounds include Burnock® D-750, -800, DN-950, -970 and 15-455 (Dainippon Ink and Chemicals Inc.), Desmodur® L, NHL, IL and N3390 (Bayer A.G., West Germany), Takenate® D-102, -202, -110N and -123N (Takeda Chemical Industries, Ltd.), Coronate® L, HL, EH and 203 (Nippon Polyurethane Industry Co., Ltd.) and Duranate® 24A-90CX (Asahi Chemical Industry Co., Ltd.); adducts of with polybasic acids; the compounds obtainable by oxidizing esters containing unsaturated groups such as (e.g. esters obtainable by esterifying tetrahydrophthalic anhydride, trimethylolpropane, 1,4-butanediol and having a number average molecular weight of about 900) with peracetic acid. Aside from the above compounds containing alicyclic epoxy groups, compounds having non-alicyclic epoxy groups, such as diglycidyl ether or 2-glycidylphenyl glycidyl ether can also be employed. As the epoxy compound (B), homopolymers of the vinyl monomers represented by the following general formulas (1) through (16) and copolymers thereof with the aforementioned α,β-ethylenically unsaturated monomers (II) can also be employed. In the above respective general formulas, R 1 means a hydrogen atom or a methyl group; R 2 means a divalent aliphatic saturated hydrocarbon group of 1 to 6 carbon atoms; R 3 means a divalent hydrocarbon group of 1 to 10 carbon atoms, and T means an integer equal to 0 to 10, inclusive. In the above formulas, the groups R 1 are the same or different, and so are the groups R 2 and the groups R 3 . Among those epoxy group-containing vinyl monomers, the use of alicyclic epoxy group-containing vinyl monomers is preferred from the standpoint of curing property. Thus, when an alicyclic epoxy group-containing vinyl monomer is employed, the addition reaction of the epoxy group to the hydroxyl group proceeds fast and the curing effect is improved. As examples of the above divalent aliphatic saturated hydrocarbon groups of 1 to 6 carbon atoms, straight-chain or branched alkylene groups such as methylene, ethylene, propylene, tetramethylene, ethylethylene, pentamethylene or hexamethylene can be mentioned. As examples of the divalent hydrocarbon group containing 1 to 10 carbon atoms, there may be mentioned methylene, ethylene, propylene, tetramethylene, ethylethylene, pentamethylene, hexamethylene, decamethylene, phenylene, As the epoxy compound (B), there may also be employed the compounds obtainable by reacting any of said high molecular weight hydroxy compounds (A) with a compound containing one isocyanate group and one epoxy group per molecule (for example, in the proportion of more than one mole of the latter compound to one hydroxyl group in the former compound so as to react all the hydroxyl groups contained in the hydroxy compound (A). The silane compound (C) is a compound containing an average of one or more functional groups selected from alkoxysilane, silanol and acyloxysilane groups (hereinafter referred to simply as silane groups) per molecule. If the average number of silane groups is less than 1, the curing performance and gel fraction ratio are decreased. On the other hand, if too many silane groups are present, the reaction between silane group and epoxy group predominates to decrease the number of epoxy groups available for reaction with hydroxyl groups to thereby adversely affect the curing performance and gel fraction ratio. Therefore, the number of silane groups in the molecule is preferably not more than 2,500 on the average. The silane compound (C) has a number average molecular weight of 104 to 200,000. Silane compounds with number average molecular weights less than 104 are hardly available, while silane compounds with number average molecular weights in excess of 200,000 are not well compatible with other components and fail to give weather-resistant cured films. As the alkoxy groups in silane compounds (C), alkoxy groups containing 1 to 6 carbon atoms are preferred. Thus, for example, methoxy, ethoxy, n-propoxy, isopropoxy and n-butoxy can be mentioned. As to acyloxy groups, those containing C 1-6 alkyl groups are preferred. Thus, acetoxy, propionyloxy or butyroxy can be mentioned by way of example. As specific examples of silane compound (C), the following compounds of classes (1) through (7) can be mentioned. (1) Compounds of general formulas (17) through (20). where all groups R 4 may be the same or different and each means a C 1-6 alkyl group or a phenyl group; all groups R 5 may be the same or different and each means a C 1-6 alkyl group, a hydrogen atom or R 6 where R 6 is a C 1-6 alkyl group. As examples of said C 1-6 alkyl group, there may be mentioned methyl, ethyl, n-propyl, iso-propyl, n-butyl, n-pentyl and n-octyl. As examples of the compound of general formula (17), there may be mentioned trimethylmethoxysilane, trimethylethoxysilane, triethylpropoxysilane, triphenylmethoxysilane, triphenylbutyloxysilane, trimethylsilanol and triphenylsilanol. As examples of the compound of general formula (18), there may be mentioned dimethyldimethoxysilane, dibutyldimethoxysilane, di-isopropyldipropoxysilane, diphenyldibutoxysilane, diphenyldiethoxysilane, diethyldisilanol, dihexyldisilanol. As examples of the compound of general formula (19), there may be mentioned methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, phenyltriethoxysilane, phenyltributoxysilane, hexyltriacetoxysilane, methyltrisilanol, phenyltrisilanol. Examples of the compound of general formula (20) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetracetoxysilane, diisopropoxydivaleroxysilane, tetrasilanol. Among these silane compounds, those having number average molecular weights from 104 to 40,000 are preferred and those in the range of 104 to 30,000 are more desirable. Silane compounds with number average molecular weights less than 104 are not readily available, while silane compounds with number average molecular weights exceeding 40,000 are not well compatible with the other components so that the cured film does not have sufficient weather resistance. (2) Homopolymers of compounds of general formula wherein A means R 7 means a hydrogen atom or a methyl group; R 8 means a divalent aliphatic saturated hydrocarbon group containing 1 to 6 carbon atoms; R 9 and R 10 may be the same or different and each means a hydroxyl group, a phenyl group, an alkyl group of 1 to 6 carbon atoms, an alkoxy group of 1 to 6 carbon atoms or an acyloxy group; R 11 means a hydrogen atom or an alkyl group of 1 to 6 carbon atoms; n is an integer equal to 1 through 10, inclusive. Referring to general formula (21), the divalent aliphatic saturated hydrocarbon group of 1 to 6 carbon atoms, represented by R 8 , is a straight-chain or branched.alkylene group such as methylene, ethylene, propylene, tetramethylene, ethylethylene, pentamethylene, hexamethylene. The alkyl group of 1 to 6 carbon atoms, represented by R 9 , R 10 and R 11 , is a straight-chain or branched alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl. The alkoxy group of 1 to 6 carbon atoms, represented by R 9 and R 10 , is a straight-chain or branched alkoxy group such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, n-hexyloxy, isohexyloxy. Referring, further, to general formula (21), where n is not less than 2, all groups R 9 and R 10 , respectively, may represent the same group or different groups. Among the compounds of general formula (21) which are used as monomers in the present invention, those in which A represents include, among others, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropyltripropoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxybutylphenyldiethoxysilane, γ-(meth)acryloxybutylphenyldipropoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldimethylethoxysilane, γ-(meth)acryloxypropylphenylmethylmethoxysilane, γ-(meth)acryloxypropylphenylmethylethoxysilane, γ-(meth)acryloxypropyltrisilanol, γ-(meth)acryloxypropylmethyldisilanol, γ-(meth)acryloxybutylphenyldisilanol, γ- (meth)acryloxypropyldimethylsilanol, γ-(meth)acryloxypropylphenylmethylsilanol, Among the compounds of general formula (21), those in which A represents include, among others, (3) Copolymers of compounds of general formula (21) with said α,β-ethylenically unsaturated monomers (II). (4) Homopolymers of polysiloxane macromonomers (for example, the macromonomers described in JP-A-275132/1987) which are obtainable by reacting 30 to 0.001 mole percent of a compound of general formula (21) with 70 to 99.999 mole percent of at least one of the compounds of general formulas (17) through (20) and have a number average molecular weight of 400 to 100,000. The number average molecular weights of these homopolymers are preferably in the range of 3,000 to 200,000, more preferably in the range of 5,000 to 80,000. (5) Copolymers of said polysiloxane macromonomers with α,β-ethylenically unsaturated monomers (II). The number average molecular weights of these copolymers is preferably 3,000 to 200,000, more preferably 5,000 to 80,000. (6) Compounds obtainable by reacting a compound containing an isocyanato group and either an alkoxysilane group or an acyloxysilane group per molecule (for example, with said hydroxy compounds (A) in the ratio of one mole of the former to one hydroxyl group in the hydroxy compounds (A) so as to react all the hydroxyl groups contained in (A). (7) Compounds obtainable by reacting said compound containing an isocyanate group and either an alkoxysilane group or an acyloxysilane group per molecule with a polyhydric alcohol, which is used as a starting material for said polyester polyol among said high molecular weight hydroxy compounds (A), in the ratio of one mole of the former to one hydroxyl group in the polyhydric alcohol, to react all the hydroxyl groups contained in the alcohol. Among the above-mentioned various silane compounds (C), the polymers derived from polysiloxane macromonomers as mentioned above under (4) and (5) are particularly advantageous in that the cured film has a high gel fraction ratio and is superior in acid resistance, impact resistance and other physical properties. The components described hereinabove can be respectively provided by the known methods. Thus, the reaction between hydroxyl and isocyanate groups, the condensation reaction of silane groups, copolymerization reaction and other reactions can all be conducted in the known manners. For example, the reaction between isocyanate and hydroxyl groups can be advantageously carried out at a temperature between room temperature and 130°C over a period of about 30 to 360 minutes. The condensation reaction of silane groups can be carried out in the presence of an acid catalyst (for example, hydrochloric acid, sulfuric acid, formic acid, acetic acid) at an elevated temperature of about 40 to 150°C for about 1 to 24 hours. The copolymerization reactions can be carried out under the same conditions as those used generally in the production of acrylic or vinyl resins. In an exemplary synthetic process, the respective monomers are dissolved or dispersed in an organic solvent and in the presence of a radical polymerization initiator, the solution or suspension is heated at a temperatures of about 60 to 180°C with constant stirring. The reaction time generally ranges from about 1 to 10 hours. As the organic solvent, the aforementioned alcohol, ether, ester or hydrocarbon solvent can be selectively employed. A hydrocarbon solvent is preferably used in combination with a different type of solvent from the standpoint of solubility. As the radical initiator, any of usual initiators can be employed. Thus, it may be any of various peroxides such as benzoyl peroxide or t-butyl peroxy-2-ethylhexanoate, and azo compounds such as azobisisobutyronitrile or azobisdimethylvaleronitrile. As the crosslinking agent, at least one of chelate compounds (D) of aluminum, titanium or zirconium is employed in the present invention. Said chelate compounds contain a compound which shows keto-enol tautomerism as a ligand forming a stable chelate ring. As examples of said compound which shows keto-enol tautomerism, there may be mentioned β-diketones (acetylacetone), acetoacetic acid esters (methyl acetoacetate), malonic acid esters (ethyl malonate), ketones having a hydroxyl group in the β-position (diacetone alcohol), aldehydes having a hydroxyl group in the β-position (salicylaldehyde), esters having a hydroxyl group in the β-position (methyl salicylate.). Particularly satisfactory results are obtained when acetoacetic esters and β-diketones are employed. The aluminum chelate can be easily prepared by mixing generally one mole equivalent of an aluminum alkoxide of the general formula wherein all groups R 13 may be the same or different and each means an alkyl group of 1 to 20 carbon atoms or an alkenyl group with about 1 to 3 mole equivalents of a compound which, as aforesaid, shows keto-enol tautomerism, if necessary with heating. The alkyl group containing 1 to 20 carbon atoms includes, in addition to the C 1-6 alkyl groups mentioned hereinbefore, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, octadecyl. As examples of said alkenyl group, there may be mentioned vinyl or allyl. As examples of the aluminum alkoxide of general formula (22), there may be mentioned aluminum trimethoxide, aluminum triethoxide, aluminum tri-n-propoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum triisobutoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide. Particularly preferred are aluminum triisopropoxide, aluminum tri-sec-butoxide and aluminum tri-n-butoxide. The titanium chelate can be prepared, for example by mixing generally one mole equivalent, as titanium, of a titanate compound of the general formula wherein m represents an integer equal to 0 through 10, inclusive, and R 13 has the same meaning as defined hereinbefore, with about 1 to 4 mole equivalents of a compound which, as aforesaid, shows keto-enol tautomerism, if necessary with heating. As examples of the titanate of general formula (23) wherein m is equal to 0, there may be mentioned, among others, tetramethyl titanate, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate, tetra-tert-butyl titanate, tetra-n-pentyl titanate, tetra-n-hexyl titanate, tetraisooctyl titanate, tetra-n-lauryl titanate. Particularly useful are tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate and tetra-tert-butyl titanate. As to the titanate of general formula (23) wherein m is 1 or more, the dimers to undecamers (m = 1 to 10) of tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate or tetra-tert-butyl titanate are preferred. The zirconium chelate can be prepared, for example by mixing generally one mole equivalent, as zirconium, of a zirconate compound of the general formula: wherein m and R 13 are as defined hereinbefore, with about 1 to 4 mole equivalents of said compound which shows keto-enol tautomerism, if necessary with heating. As examples of the zirconate of general formula (24) wherein m is equal to 0, there may be mentioned tetraethyl zirconate, tetra-n-propyl zirconate, tetra-isopropyl zirconate, tetraisobutyl zirconate, tetra-n-butyl zirconate, tetra-sec-butyl zirconate, tetra-tert-butyl zirconate, tetra-n-pentyl zirconate, tetra-tert-pentyl zirconate, tetra-tert-hexyl zirconate, tetra-n-heptyl zirconate, tetra-n-octyl zirconate, tetra-n-stearyl zirconate. Particularly preferred are tetraisopropyl zirconate, tetra-n-propyl zirconate, tetraisobutyl zirconate, tetra-n-butyl zirconate, tetra-sec-butyl zirconate and tetra-tert-butyl zirconate. As to the zirconate of general formula (24) wherein m is equal to 1 or more, the dimers to undecamers (m=1 to 10) of tetraisopropyl zirconate, tetran-propyl zirconate, tetra-n-butyl zirconate, tetraisobutyl zirconate, tetra-sec-butyl zirconate or tetratert-butyl zirconate are preferred. The zirconium chelate compound may contain an association of such zirconates as a constituent unit. Among preferred chelate compounds for purposes of this invention are such aluminum chelate compounds as tris(ethylacetoacetate)aluminum, tris(n-propylacetoacetate)aluminum, tris(isopropylacetoacetate)aluminum, tris(n-butylacetoacetate)aluminum, isopropoxybis (ethylacetoacetate)aluminum, diisopropoxyethylacetoacetatealuminum, tris(acetylacetonato)aluminum, tris(propionylacetonato)aluminum, diisopropoxypropionylacetonatoaluminum, acetylacetonatobis(propionylacetonato)aluminum, monoethylacetoacetatebis(acetylacetonato)aluminum, monoacetylacetonatobis(ethylacetoacetate)aluminum, such titanium chelate compounds as diisopropoxybis(ethylacetoacetate)titanium, diisopropoxybis(acetylacetonato)titanium, and such zirconium chelate compounds as tetrakis(acetylacetonato)zirconium, tetrakis(n-propylacetoacetate)zirconium, tetrakis(ethylacetoacetate)zirconium. If, in the practice of this invention, unchelated alkoxy compounds of aluminum, titanium or zirconium of general formulas (22) through (24), are used as crosslinking agents, the pot life is shortened so that the resulting composition cannot be used as a one-package composition. As the chelate compound to be used as a crosslinking agent in the present invention, the above-mentioned respective chelate compounds of aluminum, zirconium and titanium can be used either singly or in combination. In the present resin composition the proportions of high molecular weight hydroxy compound (A) and epoxy compound (B) are 5 to 95 weight percent, preferably 20 to 80 weight percent, for the former and 95 to 5 weight percent, preferably 80 to 20 weight percent, for the latter, both based on the combined weight of (A) and (B). If the ratio of the two compounds is outside the above range, low-temperature curability will not be as good as desired. Based on 100 weight parts of high molecular weight hydroxy compound (A) and epoxy compound (b) combined, the silane compound (C) is used in a proportion of 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight. If the proportion of silane compound (C) is less than 0.1 part by weight, curing performance will be adversely affected. On the other hand, use of (C) in excess of 50 parts by weight is also disadvantageous in that the solvent resistance of the film will be adversely affected by the residue of silane compound (C). The metal chelate compound (D) is used in a proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of high molecular weight hydroxy compound (A) and epoxy compound (B) combined. If the proportion of metal chelate compound (D) is less than 0.01 part by weight, curing performance will be adversely affected, while the use of (D) in excess of 10 parts by weight will result in reduced water resistance of the cured film. If necessary, inorganic and organic pigments may be incorporated in the resin compositions of the present invention. As examples of the inorganic pigment, there may be mentioned oxide pigments (such as titanium dioxide, red iron oxide, chromium oxide), hydroxide pigments (such as alumina white), sulfate pigments (such as precipitated barium sulfate), clay, carbonate pigments (such as precipitated calcium carbonate), carbon pigments (such as carbon black), and various metal powders (such as aluminum powder, bronze powder, zinc dust). As examples of said orgganic pigments, azo colors (such as lake red, fast yellow) and phthalocyanine colors (such as phthalocyanine blue) can be mentioned. If necessary, the resin compositions of the present invention can be used as dissolved in organic solvents. From the standpoint of curing rate of the resin composition, an organic solvent having a boiling point not exceeding about 150° is preferred, although this is not an essential requirement. Preferred organic solvents include hydrocarbon solvents such as toluene, xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, ester solvents such as ethyl acetate, butyl acetate, ether solvents such as dioxane, ethylene glycol diethyl ether, and alcohol solvents such as butanol or propanol. While these solvents may be used alone or in suitable combination, alcohol solvents are preferably used in combination with other kinds of solvents from the standpoint of solubility of the resin. While the resin concentration varies with different applications, it is generally about 10 to 70 weight percent. The resin compositions of the present invention can be used with advantage in such applications as coatings, adhesives, inks. When any of the resin compositions of the present invention is to be used as a coating material, it can be applied by any routine coating method, such as spray coating, roll coating. or brush coating. The resin compositions of the present invention can be easily cured at a low temperature not exceeding 100°C and even at room temperature without heating. In the latter case, complete cure can be achieved generally in about 8 hours to about 7 days. When the curing reaction is conducted at an elevated temperature of about 40 to 100°C, complete cure occurs in as short as about 5 minutes to about 3 hours. The reason why the resin compositions of the present invention have excellent low-temperature curability seems to be as follows. In the first place, the metal chelate compound reacts with the silane group to give the following bond. Aℓ - O - Si Then, this bond is coordinated to the silanol group (the alkoxysilane and acyloxysilane groups are converted to silanol group by humidity in the atmosphere) to polarize the silanol group as follows. This polarized silanol group reacts with the epoxy group to give the bond: The epoxy group then reacts with a hydroxyl group to give: This reaction between the epoxy and hydroxyl groups proceeds at a comparatively low temperature. Since the compositions of the present invention contain a hydroxyl group-containing compound as an essential component and, in addition, contains epoxy and silane groups and, further, a metal chelate compound, the above reaction appears to proceed very rapidly to insure excellent low-temperature curability. The resin compositions of the present invention can be implemented by using the respective components in rather liberal proportions. Therefore, the cured product tailored to the intended use can be obtained by mixing the components in suitable proportions before application. By way of illustration, the present invention may be implemented, for example, by a process in which said high molecular weight hydroxy compound (A) as a main component is cured with said epoxy compound (B), silane compound (C) and metal chelate compound (D), a process in which said epoxy compound (B) as a main component is cured with said high molecular weight hydroxy compound (A), silane compound (C) and metal chelate compound (D), or a process in which said silane compound (C) as a main component is cured with said hydroxy compound (A), epoxy compound (B) and metal chelate compound (D). If a pigment, such as titanium white, is dispersed using a resin containing epoxy, hydroxyl and silanol groups, the silanol groups contained in the resin will react with Aℓ 2 O 3 , SiO 2 and ZnO, inclusive of their hydrates, on the surface of the pigment (titanium white) to increase the thickness of the resin system or give rise to coarse particles and the metal chelate compound is also liable to react with such metal oxides and hydrates on the surface of titanium white to increase the viscosity of the system. On the other hand, in the resin compositions of the present invention, the above problem can be oby-i.ated by dispersing the pigment titanium white using said high molecular weight hydroxy compound (A). The resin compositions of the present invention insure the following advantageous effects. 1. A highly weather-resistant film can be obtained. 2. Since the curing component can be easily modified, various films tailored to intended uses can be obtained. 3. The curing reaction proceeds smoothly at low temperatures not exceeding about 100°C. 4. The composition has a long pot life and can be used as a one-package coating. 5. The cured film has excellent acid resistance. The following examples are further illustrative of the present invention. Production Example 1. Production of polysiloxane macromonomer Methyltrimethoxysilane 2720 g γ-Methacryloxypropyltrimethoxysilane 256 g Deionized water 1134 g 30% Hydrochloric acid 2 g Hydroquinone 1 g The above mixture was reacted at 80°C for 5 hours. The resulting polysiloxane macromonomer had a number average molecular weight of 2,000 and contained one vinyl group (polymerizable unsaturated bond) and 4 hydroxyl groups on the average per mol. 2. Production of compound (a) A mixture of 300 g (nonvolatile matter) of the above polysiloxane macromonomer, 100 g of styrene, 600 g of n-butyl acrylate and 20 g of azobisisobutyronitrile was added dropwise to 1,000 g of xylene at 120°C for polymerization. The procedure gave a clear copolymer. This copolymer contained an average of 12 silanol groups per molecule and had a number average molecular weight of about 20,000. Example 1 A resin composition was provided by mixing 100 g of an acrylic polyol (2-hydroxyethyl acrylate/n-butyl methacrylate/styrene/azobisisobutyronitrile = 116 g/734 g/150 g/10 g) containing an average of 30 hydroxyl groups per molecule and having a number average molecular weight of 30,000 with Example 2 A resin composition was provided by mixing 100 g of the same acrylic polyol as used in Example 1 with 30 g (nonvolatile matter) of the copolymer prepared in the production of compound (a), 20 g of and 0.5 g of tris(acetylacetonato)aluminum. [Film performance tests] Each of the resin compositions prepared in Examples 1 and 2 was coated in a dry thickness of 100 µm (provided, however, that a thickness of 50 µm was used for water resistance test and weatherability test) and cured at 80°C for 10 minutes, and the cured film was subjected to various tests. Gel fraction ratio: The dry film was peeled off from the glass substrate and extracted with refluxing acetone in a Soxhlet extractor for 6 hours. The gel fraction ratio was expressed in % residue of the film. Impact resistance: Mild steel sheet was used as the substrate. Using a DuPont impact tester, a weight of 500 g (impact core diameter of 1.27 cm (1/2 inch)) was dropped on the coated surface and the maximum dropping distance (cm) which did not cause cracking or exfoliation of the coat was determined. Water resistance: Mild steel sheet was used as the substrate. The testpiece was immersed in lukewarm water (40°C) for 60 days to check for abnormalities (blisters, whitening, loss of gloss) in the film. Weatherability: Aluminum sheet was used as the substrate. Using the QUV weather-o-meter (The Q-Panel Co., Ltd.; a fluorescent lamp No. QFS-40, UV-B, a wavelength range of 320-280 nm), an irradiation (60°C, 8 hours)-condensation (50°C, 4 hours) cycle was repeated for 2000 hours and the degree of film degradation was grossly evaluated. Acid resistance: Glass plate was used as the substrate. The testpiece was immersed in 40% aqueous H 2 SO 4 (40° and 60°C) for 5 hours and the appearance (gloss, whitening) of the coated surface was grossly evaluated. Coated surface condition: Mild steel sheet was used as the substrate. The film was checked for loss of gloss, shrinkage, cracks, exfoliation, pigment grains. Pot life: Each composition was allowed to stand in an open vessel in an environment of 20°C and 70% R.H. and the time period during which no viscosity increase took place was determined. The results of the above tests are shown in Table 1.

Claims: A resin composition comprising (A) 5 to 95 weight percent of a high molecular weight hydroxy compound containing an average of 2 or more hydroxyl groups bonded to aliphatic carbon atoms per molecule and having a number average molecular weight of 3,000 to 200,000, (B) 95 to 5 weight percent of an epoxy compound containing an average of 2 or more epoxy groups per molecule and having a number average molecular weight of 120 to 200,000, (C) 0.1 to 50 parts by weight per 100 parts by weight of (A) and (B) combined of a silane compound containing an average of 1 or more functional groups selected from alkoxysilane, silanol and acyloxysilane groups per molecule and having a number average molecular weight of 104 to 200,000, and (D) 0.01 to 10 parts by weight per 100 parts by weight of (A) and (B) combined of at least one metal chelate compound of aluminum, titanium or zirconium which contains a compound showing keto-enol tautomerism as a ligand. A resin composition according to Claim 1 wherein said high molecular weight hydroxy compound (A) contains an average of 2 to 400 hydroxyl groups per molecule, said epoxy compound (B) contains an average of 2 to 500 epoxy groups per molecule, and said silane compound (C) contains an average of 1 to 2,500 of said functional groups per molecule. A method of curing the resin composition according to Claim 1 or 2 which comprises curing said composition at a temperature not exceeding 100°C.

Inventors: ISOZAKI OSAMU, IWASAWA NAOZUMI, NAKAI NOBORU, ISOZAKI, OSAMU, IWASAWA, NAOZUMI, NAKAI, NOBORU
Applicants: KANSAI PAINT CO LTD, KANSAI PAINT CO. LTD.
Application year: 1989
Main classification: C08L101
IPC codes: C09D143, C08K5, C09D133, C09D163, C08L63, C08G59, C07F7, C08L33, C08L75, C08L101, C08L43