MXPA00001057A - Acetoacetate functional polysiloxanes - Google Patents

Abstract

Functional polysiloxanes and curable coating compositions containing such polysiloxanes are disclosed. The curable compositions are useful in coatings where they provide excellent appearance, pot-life, humidity resistance and improved adhesion to galvanized steel substrates. A method for preparing the functional polysiloxanes is also disclosed.

Description

ACETOACETATE-FUNCTIONAL POLYISYLOXANES BACKGROUND OF THE INVENTION Polysiloxane polyols are well known in the art. Japanese Patent Publication 48-19941 discloses polysiloxane polyols which are obtained by the dehydrogenation reaction between a polysiloxane hydride and an aliphatic polyhydric alcohol or polyoxyalkylene alcohol to introduce the alcoholic hydroxy groups into the polysiloxane skeleton. In practice, however, it is difficult to obtain an industrially significant yield of said polysiloxane polyols, since said dehydrogenation reaction readily gels. Another problem encountered in this dehydrogenation reaction is the difficulty in obtaining a solvent capable of dissolving both reagents. Strongly hydrophilic alcohols, such as polyglycerols, are highly soluble in alcohols and water, but insoluble in hydrocarbon solvent. The polysiloxanes, however, are generally only soluble in hydrocarbon solvents, such as toluene or n-hexane. The Pat. USA No. 4,431,789 to Oksza i et al. discloses a polysiloxane polyol which is obtained by the hydrosilylation reaction between a polysiloxane containing silicon hydride and a polyglycerol compound having an aliphatically unsaturated linkage in the molecule. Examples of such polyglycerol compounds are those obtained by the reaction of allylic alcohol and glycidol or by the reaction of diglycerin and allyl glycidyl ether. This reaction, a so-called hydrosilylation reaction, is the addition reaction between an organosilicon compound having a hydrogen atom directly attached to the silicon atom, i.e., a polysiloxane hydride, and an organic compound having unsaturation aliphatic in the molecule, carried out in the presence of a catalytic amount of a noble metal of Group VIII. The hydrosilylation reaction can easily precede in the presence of an alcoholic solvent that can dissolve both reagents. The resulting polysiloxane polyols are useful as nonionic surfactants. Pat. USA No. 5,260,469 describes butoxylated polysiloxane polyols which are described as useful in cosmetics. Acetoacetate-functional acrylic crosslinking polymers are also known in the art. Pat. USA No. 4,408,018 to Bartman et al. describes the introduction of pendant acetoacetate-functional residues in an acrylic polymer skeleton to crosslink with alpha, beta-unsaturated esters through the Michael addition reaction. Acetoacetate-functional acrylic polymers can be prepared in any of two ways. An acetoacetic ester of an acrylic monomer containing hydroxyl groups, such as hydroxyethyl methacrylate or hydroxyethyl acrylate, can be produced by transacetylation of the hydroxyl-containing acrylic monomer with an acetoacetate. These acetylated monomers can then be copolymerized with other polymerizable monomers to introduce the acetoacetate moiety in the acrylic polymer chain. Alternatively, an acrylic polymer chain having hydroxyl functionality thereon can be transesterified with an alkyl acetoacetate to introduce the acetoacetate moiety in the backbone of the acrylic polymer. The references also describe the ace-toacetylation of the hydroxyl groups of a polyester polyol to obtain a polyester containing acetoacetate.

COMPENDIUM OF THE INVENTION The present invention relates to new functional polysiloxanes and to a method for the preparation of said polysiloxanes. A curable coating composition containing the functional polysiloxanes is also disclosed. The curable coating composition containing the functional polysiloxane is easily curable at ambient temperatures and produces a cured film with excellent performance properties, such as curing speed, low VOC, excellent moisture resistance, flexibility and adhesion on galvanized iron. The functional polysiloxane having the general structural formula: R R R R (II) R-Si-O- [-Si-0-] n- [Si-0] m-Si -R I R R Ra R RRRR (ni; R-Si-O- [-Si-0-] n- [Si-0] m-Si -R Ra R Ra Ra where the group represented by R .a contains a group that has the general structure: (IV) -C-CH-C-CH3 0 0 wherein the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups connected to silicon atoms, m is at least one, ir * / is 0 to 50 and n is 0 to 50. Preferably, the group Ra has a group having the g-general structure: (I) -XC-CH-CC-3 OO wherein X is N, 0 or S. The preparation of the functional polysiloxane of structural formula (I) consists of: (a) hydrosilylation of a polysiloxane containing silicon hydride, wherein the ratio of silicon atoms to hydrosilylated silicon atoms is not Hydrosilylated is at least 0.1: 1 and, preferably, 0.1 to 10: 1, with an alcohol, primary or secondary amine or thiol containing vinyl or vinylidene groups, which are capable of hydrosilylating said polysiloxane contains silicon hydride, to obtain a polysiloxane containing hydroxyl, amine or thiol groups or mixtures thereof, and (b) esterification of the hydrosilylated reaction product of (a) with the acetoacetate to produce the acetoacetate-functional polysiloxane. The curable coating composition consists of: (a) a functional polysiloxane having the general formula (II) or (III), wherein at least one of the groups represented by Ra contains a group having the structural formula (I) or (IV), where n is 0 to 50, m is at least one, m 'is 0 to 50 and, in the case of structural formula (I), X is -N, O or S; and the other R groups are selected from the group consisting of OH and monovalent hydrocarbon groups bound to the silicon atoms, and (b) a blocked polyamine or polyamine. In the preferred embodiment of the invention, X is O. Optionally, the curable coating composition of the invention also contains a polyacrylate curing agent.

The coated substrates have on them a film consisting of the cured reaction product of the following reagents: (a) a functional polysiloxane having the general structural form (II) or (III), wherein at least one Ra group contains a group represented by the structural formula (I) or (IV), where n is 0 to 50, m is at least one, m 'is 0 to 50 and, in the case of the structural formula (I), X is -N , O or S; and the R groups are selected from the group consisting of H, OH and monovalent hydrocarbon groups, and (b) a blocked polyamine or polyamine. In the preferred embodiment of the invention, X is O. Optionally, the coated substrate may have a film thereon which additionally contains, as one of the reactants, a polyacrylate curing agent. DETAILED DESCRIPTION OF THE INVENTION The functional polysiloxane of the present invention has the general formula (II) or (III), wherein at least one of the groups represented by Ra contains a group having the general structure (I) or (IV) and , in the case of (I), where X is -N, O or S, preferably O; the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups bound to the silicon atoms, and m is at least one, m 'is 0 to 50, n is 0 to 50, preferably 0 to 35 and, more preferably, 2 to 15. By monovalent hydrocarbon groups is meant organic groups containing essentially carbon and hydrogen. The hydrocarbon groups can be aliphatic, aromatic, cyclic or acyclic and can contain from 1 to 24 (in the case of aromatic, from 3 to 24) carbon atoms. Eventually, the hydrocarbon groups may be substituted with heteroatoms, typically oxygen. Examples of such monovalent hydrocarbon groups are alkyl, alkoxy, aryl, alkaryl or alkoxyaryl groups. - Preferably, the functional polysiloxane has an equivalent weight of 100 to 1,500, more preferably 100 to 500 (grams / equivalent), based on the equivalents of acetoacetate. At least one of the groups represented by Ra typically contains a group of the following general structure: O O (V) -L - (- 0-C-CH-C-CH3)? where L is an organic group of union and x is 1 to 3. Preferably, L is alkylene, oxyalkylene or alkylenearyl. By alkylene is meant acyclic or cyclic alkylene groups having a carbon chain length of C2 to C25. Examples of suitable alkylene groups are the propene, butene, pentene, 1-decene, isoprene, myrcene and 1-heneicosene derivatives. By oxyalkylene is meant an alkylene group containing at least one ether oxygen atom and having a carbon chain length of Ci to C25, preferably of C2 to C4. Examples of suitable oxyalkylene groups are those associated with trimethylolpropane monoallyl ether, trimethylolpropane diallyl ether and ethoxylated allyl ether. By "alkylenearyl" is meant an acyclic alkylene group containing at least one aryl group, preferably phenyl, and having a carbon chain length of C2 to C25. The aryl group may be optionally substituted. Suitable substituent groups may include hydroxyl, benzyl, carboxylic acid and aliphatic groups. Examples of suitable alkylenearyl groups include styrene and 3-isopropenyl-α, α-dimethylbenzyl isocyanate. Preferably, the functional polysiloxane of the present invention is an acetoacetate-functional polysiloxane and has the following general structural formula: R R R R (vn; R-Si-0 - [- Yes-0-] n- [YES-0] m-Si-R R R RD R RRRR (VIII 'R-Si-O- [-Si-0-] n- [Si-0] m-Si-R RD R RD RD where m is at least one, m / is 0 to 50,' n is 0 to 50, R is selected from the group consisting of OH and monovalent hydrocarbon groups connected to the silicon atoms and at least a portion of the Rb groups has the following structure: (IX) R? -0-R2 - (- 0 -C-CH-C-CH 3) z 0 O or (VI) YC-CH-C-CH 3 O Ri O where R is alkylene, oxyalkylene or alkylenaryl and R 2 is alkylene, oxyalkylene or alkylenaryl and z is one to 3 and where Y is selected from the group consisting of alkyl, Cl, Br, I and OR ', preferably where R' is Ci to C 2 alkyl, When only a portion of the hydroxyl groups of the polysiloxane polyol produced in the hydrosilylation step is esterified, the rest of the Rb groups are: L-OH and / or R1-0-R2-OH where L, Rx and R2 are as defined above, Preferably, the ratio of m: n in the structure acetoacetate-functional polysiloxane (IV) is at least 0.1: 1, preferably 0.1 to 10: 1. or ratios of less than 0.1 to 1 are preferred, since these materials are typically not compatible with organic materials (ie, resins and solvents). A method of preparing the acetoacetate-functional polysiloxane of the present invention consists of: (a) hydrosilylating a polysiloxane containing silicon hydride, such as one having the structure: R R R R (X) R-Si-O- [-Si-0-] n- [Si-0] m-Si-R RRHR or RRRR R-Si-O- [-Si-0-] n- [Si-0 ] m-Si-H RRHR where the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups connected to the silicon atoms, n is 0 to 50, m is at least 1 and m 'is 0 to 50, such that the ratio of silicon atoms bonded to hydrogen with respect to silicon atoms bonded to non-hydrogen is at least 0.1: 1, preferably 0.1 to 10: 1, with an alcohol, primary amine or secondary or thiol containing vinyl or vinylidene groups capable of hydrosilylating said polysiloxane containing silicon hydride, to produce a polysiloxane containing hydroxyl, amine or thiol groups or mixtures thereof; and (b) esterifying the hydro-silylated reaction product of (a) with an acetoacetate, such as one having the structure: (XII) Y'-C-CH2-C-CH3 0 where Y 'is selected from the group group consisting of Cl, Br, I and OR ', preferably OR', where R 'is Cx to Ci2 alkyl, to produce an acetoacetate-functional polysiloxane. Alternatively, the esterification can be carried out with the alcohol before the hydrosilylation step. Preferably, n is about 0 to 50, more preferably about 0 to 35, and even more preferably 2 to 15. Examples of the polysiloxane containing silicon hydride 1,1,3,3-tetramethyldisiloxane and polysiloxane containing silicon hydrides. , where n is 4 to 5, marketed by PPG Industries, Inc. as MASIL WAX BASE. It is preferred that the polysiloxane containing silicon hydride is hydrosilylated with an alkenyl alcohol, preferably an allyl polyoxyalkylene alcohol. Examples of suitable alkenyl alcohols are polyalkylene allyl alcohols and include polyethoxylated allyl alcohol, trimethylolpropane monoallyl ether and polypropoxylated allyl alcohol. In the most preferred embodiment of the invention, the alkenyl alcohol is trimethylolpropane monoallyl ether. Typically, the preparation of the acetoacetate-functional polysiloxane is carried out in two steps: (1) a hydrosilylation step and (2) an esterification step. In step 1, the alcohol, the primary or secondary amine or the thiol are added at room temperature to a reaction vessel equipped with a means for maintaining a blanket of nitrogen. Approximately 20 to 75 ppm of sodium bicarbonate or metallic acetate salt are added at the same time to inhibit possible unwanted side reactions, such as those associated with "the condensation of acetal through a propenyl ether moiety. at 75 ° C under a blanket of nitrogen, at which time about 5% of the polysiloxane containing silicon hydride is added with stirring. A catalyst, such as a transition metal, is then added, for example nickel, nickel compounds and iridium salts, preferably chloroplatinic acid, and the reaction is allowed to produce an exotherm at 95 ° C. The addition of the remaining portion of the polysiloxane containing silicon hydride is complete while maintaining the reaction temperature at 80-85 ° C. The reaction is followed by infrared spectroscopy for the disappearance of the silicon hydride absorption band (Si-H: 2.150 cm "1). To this product is added the acetoacetate and the temperature is increased to 120 ° C under a" nitroge-no spray. During the heating, the alcohol that comes off is collected. Complete distillation provides the acetoacetate-functional polysiloxane of the present invention. The curable coating composition of the present invention consists of (a) a functional polysiloxane of structural formula (II) or (III), wherein at least one of the groups represented by Ra contains a group having the general structural formula (IV) or (I), wherein n, m, m ', R and X are as defined above for formulas (II) and (III), and (b) a blocked polyamine or polyamine. Preferably, the functional polysiloxane has the structural formula (VII) or (VIII), wherein n, m, m ', z, Ri, R2, Rb and Y are all as defined above for the formols (VI), (VII), (VIII) and (IX). Preferably, the blocked polyamine is a polyketimine having the structure: R. 5 -N - (- R 3 TH R 4 N R. (XIII) R "5 where p is 0 to 6; R3 and R4 are the same or different and are alkylene, oxyalkylene or alkylenearyl, and the groups R5 'and R5"are independently H or alkyl containing from 2 to 20 carbon atoms, preferably from 2 to 6 carbon atoms; which contains from 6 to 24 carbon atoms, and are each substantially inert to the ketimine formation reaction, and R5 'and R5"together may be part of a 3, 4, 5, or 6 member ring. In addition to ketimines, al-demines may also be used and, if not otherwise indicated, the ketimines and poly-ketimines are intended to include the aldehydes and poly-aldemines. Preferably, the polyketimine is the reaction product of a polyepoxide with a ketimine containing a secondary amine group. The polyepoxide can be selected from materials containing at least two oxirane groups in the molecule. An oxirane group can be represented by the general structural formula: (XIV) where q is at least two, R7 is H or CH3 and R8 broadly represents an organic ba- ter molecule or polymer typically composed of carbon, hydrogen, oxygen and, optionally, nitrogen and / or sulfur. Hydroxyl substituent groups may also be present and frequently are, as well as halogen and ether groups. In general, the epoxide equivalent weight ranges from about 100 to about 1,000, preferably from about 100 to about 500 and, more preferably, from about 150 to about 250. These polyepoxides can be broadly categorized as aliphatic, aromatic, cyclic, acyclic, alicyclic. or heterocyclic. A particularly preferred group of polyepoxides for use in the present invention are epoxy novolac resins, which are prepared by reaction of an epiha-lohydrin with the condensation product of an aldehyde with a monohydric or polyhydric phenol. An example is the reaction product of epichlorohydrin with a phenol formaldehyde condensate. Another particularly preferred group of polyepoxides are the polyglycidyl ethers of polyhydric aromatic alcohols, which are prepared by reaction of an epihalohydrin, such as epichlorohydrin, with an aromatic polyhydric alcohol. Suitable examples of dihydric phenols include resorcinium, catechol, hydroquinone, bis (4-hydroxyphenyl) -1, 1-isobutane, 4, 4-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1, 1-ethane, bis ( 2-hydroxynaphthenyl) methane, 1,5-hydroxynaphthalene and 4,4'-iso-propylidenediphenol, ie Bisphenol A. Bisphenol A is preferred. It should be understood that mixtures of polyepoxides can also be used in the present invention. . A specific example of a polyepoxy-do-ketimine reaction product involves the reaction of a polyamine, such as one mole of diethylenetriamine with two moles of methyl isobutyl ketone, to produce a diketimine with secondary amine functionality. Alternatively, an aldehyde, such as isobutylaldehyde or benzaldehyde, may be used in place of, or in conjunction with, the ketone to form an aldimine. This ketimine, or aldimine, then reacts with a polyepoxy, effectively depleting all the oxirane groups of the polyepoxide and giving rise to a ketimine or aldimine essentially free of all oxirane groups. By "essentially free of oxirane groups" is meant that the epoxy equivalent weight of the reaction product is measured as approximately at least 5,000 (grams / equivalents); on average the reaction product contains less than 1, more preferably, on average, less than 0.5 oxirane groups per molecule. Representative of the polyamines which may be used in the present invention are aliphatic or cycloaliphatic amines having from 2 to 200 carbon atoms and from 2 to 10 primary and / or secondary amino groups, preferably from 2 to 4 primary amino groups. Examples of suitable polyamines include ethylene diamine, propylene diamine, butylene diamine, Pentamethylenediamine, hexamethylenediamine, decamethylenediamine, 7-dioxadecane-l, 10-diamine, do-decamethylenediamine, 4, 9-dioxadodecane-l, 12-diamine, 7-methyl-4, 10-dioxatridecano-l, 13-diamine, 1.2-diaminocyclohexane, 1, 4-diaminocyclohexane, 4,4'-di-aminodiciclohexilmetano, isophorone diamine, bis (3-methyl-4-aminocyclohexyl) methane, 2, 2-bis (4-aminocyclohexyl) pro-cloth, nitrile tris (ethanoamine), bis (3-aminopropyl) methyl-amine, 2-amino-1- (methylamino) propane, 3-amino-1- (cyclohexylamino) propane and N- (2-hydroxyethyl) ethylenediamine. A particularly preferred group of polyamines which are useful in the practice of the present invention can be represented by the following structural formula: (XV) H2N- (-R3-NH) p-R4-NH2 where R3 and R can they are the same or different and represent an alkylene, oxyalkylene or alkylenearyl group which contains from 2 to 20 and, preferably, from 2 to 10 carbon atoms and p is from about 1 to 6, preferably from about 1 to 3. As non-limiting examples Suitable poly-alkylene polyamines for use in the present invention include diethylenetriamine, dipropylenetriamine and dibutylenetriamine. The aldehyde or ketone which reacts with the polyamine can be represented by the following structural formula: O (XVI) R'5-CR "5 where R5 and R'5 are independently H, C2 to C2o alkyl or C6 to C24 aryl and R5 and R'5 together may form part of a ring of 3, 4, 5 or 6 membered. examples of aldehydes and ketones suitable for use in the present invention as modifiers or blocking agents for the amine groups acetone, diethyl ketone, methyl isobutyl ketone include , diisobutyl ketone, isobutyraldehyde, hydroxybutyraldehyde, benzaldehyde, salicylaldehyde, pentanone, cyclohexanone, methylamyl ketone, ethylamyl ketone, hydroxy citronellal, isophorone and decanone Preferred ketones for use in the present invention include acetone, diethyl ketone, diisobutyl ketone, pentanone, cyclohexanone, methylamyl ketone, isophorone na, decanone and methyl isobutyl ketone and methylphenyl ketone In a preferred embodiment of the present invention, polyketimine is essentially free of function oxirane, has an average of at least two ketimine groups per molecule, preferably an average of about 2 to about 25 ketimine groups per molecule and, more preferably, from about 3 to about 6 ketimine groups per molecule, and has a mean molecular weight weighted from about 1,000 to 50,000, preferably from about 1,000 to about 10,000 and, more preferably, from about 1,000 to about 5,000, as determined by gel permeation chromatography (CPG) using a polystyrene standard. The polyamines can also be used as component (b) in the curable composition. Examples of said polyamines are those described above. Optionally, the curable coating composition of the present invention may contain a polyacrylate-functional component. The preferred polyacrylate-functional component contains at least two acryloyl groups or methacryloyl groups per molecule. As polia-crilato-functional components suitable reaction products of esterification or transesterification of matt-Riyal containing acrylate or methacrylate, such as acrylic or methacrylic acids or acrylic or methacrylic esters are included, as described in more detail below, with di-, tri- or polyvalent polyols, including polyester polyols and polyether polyols, and the reagent product of an acrylate or methacrylate containing hydroxyl groups with a polyisocyanate. The polyol used in the transesterification reaction is typically a low molecular weight diol, triol or tetrol. These polyols generally have molecular weight of formula ranging from about 50 to about 1,000, and preferably from about 100 to about 500. Examples of suitable polyols include ethylene glycol, propylene glycol, diethylene glycol, tetramethylene diol, neopentyl glycol, hexamethylene diol, 1,6-hexanediol, cyclohexanediol, bis (4-hydroxycyclohexyl) methane, glycerol, trimethylolethane, trimethylolpropane, tris (2-hydroxyethyl) isocyanurate, pentaerythritol and Bisphenol A ethoxylate . Preferably, a diol such as the ethoxylated Bisphenol is used. It should be understood, however, that, if desired, higher molecular weight polyols, such as oligomeric or polymeric polyols, can be used to prepare the polyacrylate-containing material. As indicated above, the polyacrylate-functional material can also be the reaction product of a polyisocyanate and an acrylate or methacrylate containing hydroxyl groups. The polyisocyanate is typically a low molecular weight diisocyanate or triisocyanate having a formula weight of about 200 to 1,000, and preferably about 200 to 600. Examples of suitable polyisocyanate materials include toluene diisocyanate, diisocyanate of 4.4. '-diphenylmethane, isophorone diisocyanate, tris (toluene diisocyanate) trimethylolpropane, 1,6-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate and 4,4'-methylenebis (cyclohexyl isocyanate). It should be understood, however, that, if desired, higher molecular weight polyisocyanates, such as oligomeric or polymeric materials, may be used to prepare the polyacrylate-functional material. The material containing acrylate or methacrylate, which reacts with the aforementioned polyol or polyisocyanate to produce the polyacrylate-functional material can be represented by the general structural formula: R9 0 I (XVII) CH2 = C-CO-Rio where Rg is H or CH3 and Rio is H, alkyl containing one to 20 carbons or hydroxyalkyl containing 1 to 20 carbons. Non-limiting examples of suitable materials containing acrylate or methacrylate include acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, ethyl, butyl acrylate, hexyl acrylate and 2-hydroxyethyl acrylate. The polyacrylate-functional materials used in the present invention generally have a weight average molecular weight of about 100 to about 50,000 determined by CPG using a polystyrene standard. In the preferred embodiment of the present invention, the polyacrylate-functional materials are low molecular weight materials having a formula weight generally of from about 100 to about 5,000 and, more preferably, from about 100 to about 500. As examples of Suitable polyacrylate-functional materials include 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, ethoxylated bisphenol A diacrylate and tris (2-hydroxyethyl) isocyanurate triacrylate.

Although we do not intend to be bound by any theory, we believe that the functional polysiloxane and the polyacrylate-functional material, if present, react with the polycetimine to cure the claimed coating compositions. We believe that the reaction proceeds by the release of ketones from the polyketimine that exposes the primary amines, which we believe react with the acetoacetate-functional polysiloxane and, if present, the polyacrylate-functional material. Eventually, an effective amount of acid catalyst can be used to accelerate curing. Examples of suitable acid catalysts include stearic acid, isostearic acid, undecylenic acid and phosphoric acid. It should be understood that any organic or inorganic acid could serve as a catalyst, but it is preferred that the acid be monofunctional. If used, the acid is generally present in minor amounts, typically from about 0.1 to about 1.0 weight percent, based on the percentage in total weight of the resin solids. It is preferred that the curable coating composition of the present invention be essentially free of strong base. By "strong base" it is understood that the pKb of the base is greater than or equal to 11. By "essentially free of strong base" it is understood that no more than 1 weight percent is present, based on the percentage in the total weight of the resin solids, in the composition. It is believed that the presence of a strong base catalyzes the addition of Michael between the acetoacetate-functional polysiloxane and, if present in the composition, the polyacrylate-functional material. (See Clemens et al., "A Comparison of Catalysts for Crosslink-ing Acetoacetylated Resins via the Mi-chael Reaction," Journal of Coatings Technology, Vol. 61, No. 770, March 1989). Curing by this Michael reaction is undesirable, since it has been found to result in an unacceptably reduced life of the coating composition. The curable coating compositions of the invention can be pigmented or non-pigmented. Suitable pigments for colored layers include opaque, transparent and translucent pigments generally known for use in coating applications. Examples include titanium dioxide, zinc oxide, antimony oxide, iron oxide, carbon black and phthalocyanine blue. Metallic pigments, such as aluminum flakes and metal oxide coated micas, can also be used. The coatings may also contain extender pigments, such as calcium carbonate, clay, silica, talc, etc. When pigment is used, it is typically present in the composition in amounts such that the pigment to binder ratio is from about 0.03 to 6.0: 1. In addition to the above components, the coating compositions of the invention may include one or more optional ingredients, such as plasticizers, anti-oxidants, light stabilizers, ohocides and fungicides, surfactants and additives for flow control or catalysts, such as It is well known in the art. The components present in the curable coating composition of the present invention are generally dissolved or dispersed in an organic solvent. Organic solvents which may be used include, for example, alcohols, ketones, aromatic hydrocarbons, esters or mixtures thereof. Specific examples include ethanol, acetone, methyl ethyl ketone, methyl amyl ketone, xylenes and butyl acetate. Typically, the organic solvent is present in amounts of 5 to 80 percent by weight based on the total weight of the composition. The coating compositions of the invention are particularly useful as outer layers and particularly as primers. Due to their low temperature curing properties, they are particularly suitable for use in automotive refinishing applications. Once the functional polysiloxane component and the blocked polyamine or polyamine component come in contact with each other, the coating composition will begin to cure under ambient conditions. Accordingly, it is desirable to prepare the compositions in the form of a two-packet system, with the polyamine or polyamine component blocked in one package and the functional polysiloxane component and, optionally, the polyacrylate-functional material in a second package. The functional polysiloxane is generally present in the curable coating composition of the present invention in amounts of from 5 to about 65 and, preferably, from about 10 to about 25 weight percent based on the total weight of the solids of resin. The blocked polyamine or polyamine is generally present in amounts of from about 25 to about 65 and, preferably, from about 35 to about 55 weight percent based on the total weight of the resin solids. The eventual polyacrylate-functional material may be present in amounts of up to 15 and, preferably, from about 2.5 to about 7.5 weight percent, based on the total weight of the resin solids.

The coating composition of the invention can be applied to the substrate by any conventional method, such as brush, dip, flow coating, roller coating and spraying. Typically, they are applied more frequently by spraying. The compositions can be applied on a wide variety of primed and unprimed substrates, such as wood, metal, glass, cloth, plastic, leather, foams and the like. Although the compositions can be cured at ambient temperatures, they can be cured at elevated temperatures to accelerate curing. An example would be forced air curing in a downstream booth at approximately 40 ° to 60 ° C, which is common in the automotive refinish industry. The compositions of the invention in pigmented form can be applied directly to a substrate to form a colored layer. The colored layer may be in the form of a primer for subsequent application of an outer layer or may be a colored outer layer. When used as a primer coating, thicknesses of 0.4 to 4.0 mils are typical. When used as a colored outer layer, coating thicknesses of about 0.5 to 4.0 mils are customary. When applying composite coatings using the coating composition of the present invention, the initially applied coating can be cured before the application of the second layer. Alternatively, the coating may be applied by a wet-on-wet technique in which a second coating is applied to the first coating (usually after a flash time at room temperature or at a slightly elevated temperature to remove the solvent or diluent, but insufficient time to cure the coating) and the two coatings are co-cured in a single step. Only one of the coatings in the composite coating needs to be based on the coating composition of the present invention. The other coating composition can be based on a film-forming system containing a thermoplastic and / or thermosetting film-forming resin known in the art, such as cellulosics, acrylics, polyurethanes, polyesters including alkyds, aminoplasts, epoxies and their mixtures These film-forming resins are typically formulated with various other coating ingredients, such as pigments, solvent and optional ingredients mentioned above. The curable compositions of the present invention are particularly useful as surface priming coating compositions for automotive refinish applications. The compositions can be applied by any of the above means of application directly to bare metal surfaces and, after allowing to dry and preparing the finish such as by sanding, directly coated with a colored outer layer or a color-transparent composite coating. . The claimed coating compositions can be used as a single primer or sublayer below an outer layer, substituting the independent sublayers that were historically necessary to obtain optimum results. The following examples illustrate the invention and are not to be considered as limiting its scope. Unless otherwise indicated, all percentages and amounts are by weight.

EXAMPLE 1 This example describes the preparation of a disiloxane tetrol, a product of the hydrosilylation step in the preparation of the acetoacetate-functional polysiloxane of the present invention. The disiloxane tetrol was prepared from the following mixture of ingredients: To a suitable reaction vessel equipped with a medium for holding a blanket of nitrogen, Charge I and an amount of sodium bicarbonate equivalent to 20 to 25 ppm of total monomer solids were added under ambient conditions and the temperature was gradually increased. at 7 ° C under a blanket of nitrogen. At that temperature, about 5.0% of Charge II was added with stirring, followed by addition of Charge III, equivalent to 10 ppm of active platinum based on the total monomer solids. The reaction was then allowed to produce an exotherm at 95 ° C, at which time the remainder of Charge II was added at a rate such that the temperature did not exceed 95 ° C. After completion of this addition, the reaction temperature was maintained at 95 ° C and followed by infrared spectroscopy for the disappearance of the absorption band of the silicon hydride (Si-H, 2150 cm-1). EXAMPLE 2 This example describes the preparation of a polysiloxane tetrol, a product of the MASIL WAX BASE siloxane hydrosilylation with an approximate degree of polymerization of 3 to 4, ie (SiO) 3 a (SiO) 4. The siloxane tetrol was prepared from the following mixture of ingredients: 1 Polysiloxane containing silicon hydride, marketed by PPG Industries, Inc. To a suitable reaction vessel equipped with a means to maintain a blanket of nitrogen, Charge I and an amount of sodium carbonate equivalent to 20 to 25 ppm were added. of total monomeric solids under ambient conditions and the temperature was gradually increased to 75 ° C under a blanket of nitrogen. At that temperature, about 5.0% of Charge II was added with stirring, followed by addition of Charge III, equivalent to 10 ppm of active platinum based on the total monomer solids. The reaction was then allowed to produce an exotherm at 95 ° C, at which time the remainder of Charge II was added at a rate such that the temperature did not exceed 95 ° C. After completion of this addition, the reaction temperature was maintained at 95 ° C and followed by infrared spectroscopy for the disappearance of the absorption band of the silicon hydride (Si-H, 2150 cm-1). EXAMPLE 3 This example describes the preparation of a disiloxane proposildiol, a product of the hydrosilylation stage of tetramethyldisiloxane. The disiloxane proposildiol was prepared from the following mixture of ingredients: 1 Marketed as ARCAL AP1375 by ARCO Chemical Company. To a suitable reaction vessel equipped with a means to maintain a blanket of nitrogen, Charge I and an amount of sodium bicarbonate equivalent to 20 to 25 ppm of total monomer solids were added under ambient conditions and the temperature was gradually increased. at 75 ° C under a blanket of nitrogen. At that temperature, approximately 5.0% of Charge II was added with stirring, followed by addition of Charge III, equivalent to 10 ppm of active platinum based on the total monomer solids. The reaction was then allowed to produce an exotherm at 95 ° C, at which time the remainder of Charge II was added at a rate such that the temperature did not exceed 95 ° C. Upon completion of this addition, the reaction temperature was maintained at 95 ° C and followed by infrared spectroscopy for the disappearance of the absorption band of the silicon hydride (Si-H, 2150 crrY). EXAMPLE 4 This example describes the preparation of a polysiloxane propoxyldiol, a product of the hydrosilylation of MASIL WAX. The polysiloxane propoxyldiol was prepared from the following mixture of ingredients: 1 Marketed as ARCAL AP1375 by ARCO Chemical Company. 2 Polysiloxane containing silicon hydride, marketed by PPG Industries, Inc. To a suitable reaction vessel equipped with a medium for holding a blanket of nitrogen, Charge I and an amount of sodium bicarbonate equivalent to 20 to 25 ppm were added. of total monomeric solids under ambient conditions and the temperature was gradually increased to 75 ° C under a blanket of nitrogen. At that temperature, about 5.0% of Charge II was added with stirring, followed by addition of Charge III, equivalent to 10 ppm of active platinum based on the total monomer solids. The reaction was then allowed to produce an exotherm at 95 ° C, at which time the remainder of Charge II was added at a rate such that the temperature did not exceed 95 ° C. After completion of this addition, the reaction temperature was maintained at 95 ° C and followed by infrared spectroscopy for the disappearance of the ab sorption band of the silicon hydride (Si-H, 2150 cm 1). EXAMPLE 5 This example describes the preparation of a styrenated polysiloxane polyol, a product of the hydrosilylation of a polysiloxane with an approximate degree of polymerization of 34, ie, (Si-0) 3. The polysiloxane polyol was prepared from the following mixture of ingredients: 1 Polysiloxane (Si-0) 34 containing silicon hydride. To a suitable reaction vessel equipped with a means for maintaining a blanket of nitrogen, Charge I was added under ambient conditions. 135 microliters of a 7-fold solution was added to the reaction vessel., 5% chloroplatinic acid, equivalent to 10 ppm of active platinum based on total monomeric solids. The temperature was gradually increased to 80 ° C under a blanket of nitrogen. The reaction was then allowed to produce an exotherm at 151 ° C and then cooled again to 80 ° C, at which time Charge II was added with 70 ppm of potassium acetate. The reaction was allowed to again produce an exotherm to approximately 150 - before cooling and maintaining it at 95 ° C, while monitoring by infrared spectroscopy as to the disappearance of the absorption band of the silicon hydride ( Si-H, 2150 cm "1) EXAMPLE 6 This example describes the acetoacetylation of the disiloxane tetrol of Example 1 to produce the acetoacetate-functional polysiloxane of the present invention The acetoacetate-functional polysiloxane was prepared from the following mixture of ingredients : To a suitable reaction vessel equipped with a means for maintaining a nitrogen spray, Charge I and Charge II were added under ambient conditions. The temperature was gradually increased to 120 ° C under a nitrogen spray. During the heating, the tertiary butaneol that was falling off was collected and the atmospheric distillation continued for approximately one hour at 120 ° C, at which time the remaining t-butanol was removed by vacuum distillation (at 30 mm Hg). ). The completion of the distillation gave the acetoacetate-functional polysiloxane of the present invention, which was confirmed by the OH value, the volume of tertiary butanol collected and the disappearance of OH determined by IR analysis. In addition, the structure could be determined by NMR and element analysis. EXAMPLE 7 This example describes the acetoacetylation of the polysiloxane tetrol of Example 2 to produce the acetoacetate-functional polysiloxane of the present invention. Acetoacetate-functional polysiloxane was prepared from the following mixture of ingredients: To a suitable reaction vessel equipped with a means for maintaining a nitrogen spray, Charge I and Charge II were added under ambient conditions. The temperature was gradually increased to 120 ° C under a nitrogen spray. During the heating, the tertiary butaneol that was falling off was collected and the atmospheric distillation continued for approximately one hour at 120 ° C, at which time the remaining t-butanol was removed by vacuum distillation (at 30 mm Hg). ). The completion of the distillation gave the acetoacetate-functional polysiloxane of the present invention, which was confirmed by the methods of Example 6. EXAMPLE 8 This example describes the acetoacetylation of the polysiloxane propoxyldiol of Example 4 to produce the acetoacetate-functional polysiloxane of the present invention. The acetoacetate-funcíonal polysiloxane was prepared from the following mixture of ingredients: To a suitable reaction vessel equipped with a means for maintaining a nitrogen spray, Charge I and Charge II were added under ambient conditions. The temperature was gradually increased to 120 ° C under a nitrogen spray. During the heating, the tertiary butanol that was falling off was collected and the atmospheric distillation continued for approximately one hour at 120 ° C, at which time the remaining t-butanol was removed by vacuum distillation (at 30 mm Hg). The completion of the distillation gave the acetoacetate-functional polysiloxane of the present invention, which was confirmed by the methods of Example 6. EXAMPLE 9 This example describes the acetoacetylation of the styrenated polysiloxane polyol of Example 5 to produce the acetoacetate-functional polysiloxane of the present invention. Acetoacetate-functional polysiloxane was prepared from the following mixture of ingredients: To a suitable reaction vessel equipped with a means for maintaining a blanket of nitrogen, Charge I and Charge II were added under ambient conditions. The temperature was gradually increased to 120 ° C under a blanket of nitrogen. During the heating, the tertiary butanol that was falling off was collected and the atmospheric distillation continued for approximately one hour at 120 ° C, at which time the remaining t-butanol was removed by vacuum distillation (at 30 mm Hg). The completion of the desylation gave the acetoacetate-functional polysiloxane of the present invention, which was confirmed by the methods of Example 6. EXAMPLE 10 This example describes the preparation of a curable two-component primer coating composition, which contained disiloxane tetrol acetoacety-side of Example 6. The premixed crosslinking component, containing the disiloxane tetrol acetoacety-side, was combined with agitation with the pigmented component, which is marketed as NCP-270 by PPG Industries, Inc., just before the application to a metallic substrate. 1 Reaction product of an epoxy novolac (EPN 1139) from Ciba Geigy and diethylenetriamine ketimine and methylbutylketone methylis. 2 BYK-Chemie moisturizing agent. 3 Wax dispersion of Rheox Inc. 4 Anti-settling agent of Rheox Inc. 5 Adhesion promoter available as A-187, from OSi Specialties Inc. 6 Bisphenol A diacrylate, from Sartomer Corp. 7 Isophorone diamine ketimine and MIBC. 8 Acrylic copolymer of styrene, diethylaminoethyl methacrylate, methyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate (weight ratio 23.1 / 21.5 / 18.5 / 18.0 / 9 2 / 9.2); 60% solids in butyl acetate. EXAMPLE 11 This example describes the preparation of a two component curable primer coating composition containing the acetoacetylated polysiloxane tetrol of Example 7 according to the present invention. The premixed crosslinking component containing the acetoacetylated polysiloxane tetrol was combined with agitation with the pigmented component, which is marketed as NCP-270 by PPG Industries, Inc., just prior to application to a metal substrate. 1 Acetoacetylated polymer made with neopentyl glycol / trimethylolpropane / ethylene glycol / cyclohexyldimethylene / isophthalic anhydride / tertiary butyl 1-cyclohexyldicarboxylic acid / acetoacetate (weight ratio 2.4 / 16.7 / 2.9 / 3, 3 / 7.7 / 8.0 / 59.0). COMPARATIVE EXAMPLE 12 By way of comparison, this example describes the preparation of a two component curable primer coating composition which contains in the crosslinking component only one acetoacetate-functional polyester, without acetoacetate-functional siloxane. The premixed crosslinking component, which contains acetoacetylated polyester and is marketed as NCX 275 by PPG Industries, Inc., is combined with agitation with the pigmented component, which is marketed as NCP-270 by PPG Industries, Inc., just before the application to a metallic substrate.

Before the coating, test panels of various metal substrates were prepared by mechanical abrasion of the surface with a sandpaper machine and cleaning the panel of the sanding residues. Each of the above primer coating compositions of Example 10 and Comparative Example 12 was applied by spraying using a conventional spray equipment to a variety of metal substrate test panels and allowed to cure at ambient conditions for two hours. A basecoat / clearcoat system, DBC-9700 / DCÜ-2020, marketed by PPG Industries, Inc., was applied by spraying using conventional spray equipment and allowed to cure at ambient conditions for a week. The multilayer coating system was studied in terms of adhesion under various conditions. Each of the primer coating compositions of the foregoing Example 11 and Comparative Example 12 was applied by spraying using conventional spray equipment to study cold-rolled steel panels and an electrogalvanized steel substrate that had been mechanically abraded and cleaned. all the sanding residue. The primer coatings were allowed to cure at ambient conditions for two hours. A commercial outer layer, DCC-9300, was applied by PPG Industries, Inc. using a conventional spray equipment and allowed to cure at ambient conditions for a week. The multilayer system was studied in terms of adhesion under various conditions. These formulations were examined for adhesion to a variety of substrates by means of ASTM D-3359. The results are given on a scale of 0-5, with 5 representing 100% adhesion and 0 representing an adhesion loss of more than 65%. A score of 4 represents an adhesion loss of less than 5%, 3 represents a loss of adhesion of 5-15%, a 2 represents an adhesion loss of 15-35% and 1 represents a loss of adhesion of 35-65%. Adhesion was also determined after the moisture resistance test. Moisture resistance is achieved by placing the cured panels in a cabinet maintained at 100 ° F and 100% relative humidity for a total of 96 hours. The panels were then removed and examined for adhesion immediately and again after 4 hours of recovery at room temperature and humidity. The results of the test for Example 10 and Comparative Example 12 are summarized in the following TABLE 1. The results for Example 11 and Comparative Example 12 are summarized in the following TABLE 2.

TABLE 1 TABLE 2 EXAMPLE 13 This example describes the preparation of a curable two-component sealant coating composition containing the acetoacetylated polysiloxane tetrol of Example 7 according to the present invention. The premixed crosslinking component containing the acetoacetylated polysiloxane tetrol with stirring was combined with the pigmented component just prior to application to a metal substrate. 1 Wetting agent marketed as DISPER-BYK 163 by BYK-Chemie USA. 2 Polymethylsiloxane solution marketed as DC-200 by Dow Corning Corp. 3 Diethylenetriamine methylamyl ketone ketone, 78% resin solids in methylamyl ketone. COMPARATIVE EXAMPLE 14 By way of comparison, this example describes the preparation of a two component curable sealant coating composition containing, in the crosslinking component, only an acetoacetate-functional polyester, without acetoacetate-functional siloxane. The premixed crosslinking component, which contains the acetoacetate-functional polyester, was combined with agitation with the pigmented component just before application to a metal substrate.

Test panels were prepared by hand sanding APR24711 test panels supplied by ACT Laboratories, Inc., with 360 grit paper, to remove contaminants and clean to remove sanding residue. The sealing coating formulations of Example 13 and Comparative Example 14 were spray applied to test panels prepared using conventional spray equipment and allowed to cure in ambient conditions for 4 hours. A commercial basecoat / clearcoat system, DBU-3822 / DCÜ-2001, from PPG Industries, Inc., was applied to the cured stoppers and allowed to cure at room conditions for a week. The multilayer coating systems were then studied in terms of the resistance to flaking by impacting the coated panels with 3 mm steel projectiles and varying the speeds to -22 ° C. The results are given as the average area of coating that exhibits failure caused by impacts at each of three impact velocities. The results of the chipping resistance test are given for the sealing coatings of Example 13 and Comparative Example 14 in the following TABLE 3 TABLE 3

Claims (46)

Claims

1. An acetoacetate-functional polysiloxane having the following general structural formula: R R R R

I I I I R-Si-O- [-Si-0-] n- [Si-0] m-Si-R R R Ra R O

RRRR R-Si-O- [-Si-0-] n- [Si-0] m-Si -R Ra R Ra Rd where the group represented by Ra contains a group having the general structure: -C-CH- C-CH3 0 0 wherein the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups connected to the silicon atoms, m is at least one, m 'is 0 to 50 and n is 0 to 50. 2. The polysiloxane acetoacetate functional group of claim 1, wherein the group represented by Ra contains a group having the general structure: -XC-CH-C-CH3 0 0 where X is N, 0 or S. 3. The functional polysiloxane of the claim 1 having an equivalent weight of 100 to 1,500 (grams / equivalent), based on the equivalents of ace-toacetate groups.

4. The functional polysiloxane of claim 2, wherein at least one of the groups represented by Ra contains a group having the general structure: 0 -L- (-0-C-CH-C-CH3) x where L is an organic linking group y'x is 1 to 3.

5. The functional polysiloxane of claim 4, wherein L is alkylene, oxyalkylene or alkylearyl.

6. The functional polysiloxane of claim 5, wherein the oxyalkylene group is a C4 to C2o-7 oxyalkylene group. The functional polysiloxane of claim 2 having the following general structural formula: R R R R I I I R-Si-O- [-Si-0-] n- [Si-0] m-Si-R R R RL R R R R R R-Si-O- [-Si-0-] n- [Si-0] m-Si-R IIII Rb R Rb Rb where m is at least one, m 'is 0 to 50, n is 0 to 50, R is selected from the group consisting of OH and monovalent hydrocarbon groups connected to silicon atoms, Rb has the following structure: R1-O-R2- (-0-C-CH2-C-CH3) OO or YC-CH-C-CH3 O Ri O where Ri is alkylene, oxyalkylene or alkylenaryl and R2 is alkylene and Y is selected from the group consisting of in Cl, Br, I and OR ', where R' is C 1 to C 2 alkyl, oxyalkylene or alkylenaryl, and z is one to 3. The functional polysiloxane of claim 6, wherein the ratio n: m and n: m ' is about 0.1 to 10: 1. 9. The functional polysiloxane of claim 6 having an equivalent weight of 100 to 1500 (grams / equivalents), based on equivalents of acetoacetate groups. 10. A functional polysiloxane which is the reaction product of the following reagents: (a) a polysiloxane containing silicon hydride, represented by the general formula: R R R R IIII R-Si-O- [-Si-0-] n- [Si-0] m-Si-R RRHR or RRRR H-Si-O- [-Si-0-] n- [Si-0] m -Si-H IIII R R H R where the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups connected to the silicon atoms; n is 0 to 50, m is at least one and m 'is 0 to 50, such that the ratio of silicon atoms bonded to hydrogen with respect to silicon atoms not bound to hydrogen is about 0.1 to 10. :1; (b) an alcohol containing vinyl or vinylidene groups which are capable of hydrosilylating said polysiloxane containing silicon hydride, and (c) an acetoacetate. 11. The functional polysiloxane of claim 10, wherein the acetoacetate has the following general structure: O O CH3-C-CH-C-Y where Y is selected from the group consisting of Cl, Br, I and O-R ', where R' is Ci to C12 alkyl. The functional polysiloxane of claim 10, wherein the polysiloxane containing silicon hydride is 1,1,3,3-tetramethyldisiloxane. The functional polysiloxane of claim 10, wherein n + m and n + m 'are 3 to 4. The functional polysiloxane of claim 10, wherein the alcohol is an allyl polyoxyalkylene alcohol. 15. The functional polysiloxane of claim 10, wherein the alcohol is trimethylolpropane monoallyl ether. 16. The functional polysiloxane of claim 10, wherein the alcohol is polyethoxylated allyl alcohol. 1

7. The functional polysiloxane of claim 10, wherein the acetoacetate is selected from the group consisting of methyl acetoacetate, ethyl acetoacetate, t-butyl acetoacetate, alpha-methyl acetate and haloacetoacetate. 1

8. A method of preparing an acetoacetate-functional polysiloxane consisting of: (a) hydrosilylating a polysiloxane containing silicon hydride, wherein the ratio of silicon atoms bonded to hydrogen with respect to silicon atoms not bound to hydrogen is about 0.1 to 10: 1, with an alcohol, a primary or secondary amine or a thiol containing vinyl or vinylidene groups which are capable of hydrosilylating said polysiloxane containing silicon hydride, to obtain a polysiloxane containing hydroxyl groups, amine or thiol or mixtures thereof, and (b) esterifying the hydro-silylated reaction product of (a) with an acetoacetate to produce an acetoacetate-functional polysiloxane. 1

9. The method indicated in claim 18, wherein the polysiloxane containing silicon hydride is hydrosilylated with an alcohol containing vinyl or vinylidene groups. 20. The method indicated in claim 18, wherein the acetoacetate-functional polysiloxane has the general form-mule: R R R R R-Si-O- [-Si-0-] n- [Si-0] m-Si -R R R Rc R or R R R R R-YES-0- [-si-o-] n- [YES-O; -Si-R Rc R Rc RL where the group represented by R contains a group having the general structure: -0-C-CH-C-CH3 ipoo where the R groups are selected from the group consisting of OH and monovalent hydrocarbon groups connected to the silicon atoms, m is at least one, m 'is 0 to 50 and n is 0 to 50. 21. The method indicated in claim 18, wherein the acetoacetate is t-butyl acetoacetate. 22. The method indicated in claim 18, wherein the alcohol is a polyoxyalkylene alkenyl alcohol. 23. The method indicated in claim 18, wherein the alcohol is selected from the group consisting of trimethylolpropane monoallyl ether, pentaerythritol monoallyl ether, polyethoxylated allyl alcohol, poly-butoxylated allyl alcohol, propoxylated allyl alcohol or mixtures thereof. 24. A curable coating composition comprising: (a) a functional polysiloxane having the following general structural formula: R R R R I R-Si-O- [-Si-0-] n- [YES-0] m-Si-R I R R Rd R RRRR R-Si-O- [-Si-0-] n- [Si-0] m-Si -R IIII Ra R Ra Ra where the group represented by Ra contains a group having the general structure: -C-CH -C-CH 3 or where the R groups are selected from the group consisting of H, OH and monovalent hydrocarbon groups connected to the silicon atoms, m is at least one, m 'is 0 to 50 and n is 0 to 50, and (b) a blocked polyamine or polyamine. 25. The curable coating composition of claim 24, wherein the group represented by Ra contains a group having the general structure: -XC-CH-C-CH3 or wherein X is N, O or S. 26. The composition of curable coating indicated in claim 25, wherein the functional polysiloxane has an equivalent weight of 100 to 1,500 (grams / equivalent), based on equivalents of acetoacetate groups. 27. The curable coating composition disclosed in claim 25, wherein at least one of the functional polysiloxane groups represented by Ra contains a group of general structure: 0 -L - (- 0-C-CH-C- CH3) x where L is an organic linking group and x is 1 to 3. 28. The curable coating composition indicated in claim 27, wherein L is alkylene, oxyalkylene or alkylearyl. 29. The acetoacetate-functional polysiloxane of claim 28, wherein L is a C4 oxyalkylene group C2o-30. The curable coating composition indicated in claim 24, wherein the ratio of m: n is from about 0.1 to 10: 1. 31. The curable coating composition of claim 24, wherein (b) is a polyketimine having the following general structure: R '. £ 5 R. Kl where p is 0 to 6; R3 and R are the same or different and are alkylene, oxyalkylene or alkylenearyl, and R5 'and R5"are independently H or alkyl containing from 2 to 20 carbon atoms, or aryl containing from 3 to 24 carbon atoms, and are each substantially inert to the ketimine formation reaction, and R5 'and R5"together may be part of a 3, 4, 5, or 6 member ring. 32. The coating composition of claim 24, wherein the polyketimine is the re-action product of a polyepoxide with a ketimine containing a secondary amine group. 33. The coating composition of claim 32, wherein the polyketimine is essentially free of oxirane functionality, has an average of at least two ketimine groups per molecule and has a weight average molecular weight of from about 1,000 to about 50,000. 34. The coating composition of claim 32, wherein the polyepoxide is a polyglycidylether of a polyhydric alcohol. 35. The coating composition of claim 24, further comprising a polyacrylate-functional component. 36. The curable coating composition of claim 35, wherein the polyacrylate-functional component has at least two acrylate groups per molecule and a weight average molecular weight of from about 100 to about 50,000. 37. The composition indicated in claim 35, where the polyacrylate is prepared by the reaction of acrylic or methacrylic acid and a polyol. 38. The composition of claim 37, wherein the polyol is selected from the group consisting of 1,6-hexanediol, trimethylolpropane, pentaerythritol and ethoxylated bisphenol A. 39. The composition of claim 35, wherein the polyacrylate is prepared by reacting a polyisocyanate with an acrylate or methacrylate monomer containing hydroxyl groups. 40. A coated substrate having thereon a film consisting of the cured re-action product of the following reagents: (a) an acetoacetate-functional polysiloxane having the following general structural formula: R R R R I I I I R-Si-O- [-Si-0-] n- [Si-0] m-Si -R R R Rd R RRRR R-Si-O- [-Sí-0-] n- [Si-0] m-Si -R Ra R Ra Rd where the group represented by R .aa contains a group that has the general structure: -C- CH-C-CH3 IT j TT oo where the R groups are selected from the group consisting of H, OH and monovalent hydrocarbon groups connected to the silicon atoms, m is at least one, m 'is 0 to 50 and n is 0 to 50, and (b) a blocked polyamine or polyamine. 41. The coated substrate of claim 40, wherein the group represented by Ra contains a group having the general structure: -X-C-CH-C-CH3"| "O Where X is N, O or S. 42. The coated substrate of claim 40, wherein (b) is a polyketimine having the following structure: R '<; - * 5 * 5". where p is 0 to 6; R3 and R are the same or different and are alkylene, oxyalkylene or alkylenearyl, and R5 'and R5"are independently H or alkyl containing from 2 to 20 carbon atoms, or aryl containing from 3 to 24 carbon atoms, and are each substantially inert to the ketimine formation reaction, and R5 'and R5"together may be part of a 3, 4, 5, or 6 member ring. 43. The coated substrate of claim 40, wherein the polyketimine is the reaction product of a polyepoxide with a ketimine containing a secondary amine group. 44. The coated substrate of claim 40, further containing, as one of the reactants, a polyacrylate-functional component. 45. The coated substrate indicated in claim 40, wherein said cured film further contains a pigment or mixture of pigments. 46. The coated substrate indicated in claim 44, wherein said cured film further contains a pigment or mixture of pigments.