PIGMENTED COATINGS FOR CERAMIC SUBSTRATES

Abstract: A crosslinking composition, especially useful as a component of a composition useful for coating ceramic substrates, comprises (a) amino-functional curing agent; (b) blocked polyisocyanate; and, optionally, (c) organo-functional siloxane comprising a member selected from the group consisting of epoxy-functional siloxane, amino-functional siloxane, (blocked isocyanato)-functional siloxane, and a mixture of two or more thereof. The composition useful for coating ceramic substrates comprises (a) reactive organic resin which is polyhydroxy-functional, polyepoxy-functional, or epoxy-functional and hydroxy-functional; (b) color-imparting pigment; (c) reactive wax; and (d) the above crosslinking composition. The coating composition may be applied to ceramic substrates and cured. The preferred ceramic substrates are glass bottles.

Description: PIGMENTED COATINGS FOR CERAMIC SUBSTRATES Cross Reference to Related Applications This application is a continuation-in-part of application Serial No. 09/359,473, filed July 22, 1999. Background of the Invention Ceramic substrates, especially those of glass, are often coated, either locally or completely, with one or more coating compositions. Local application is usually practiced to apply lettering, designs, or other indicia to the ceramic substrates; when used in this manner the coating compositions are generally referred to as " inks" . Application of indicia to glass bottles is a commercially important example. The coatings applied to bottles must be tough and resistant to marring by abrasion or impact and they should be resistant to degredation by caustic solutions commonly employed for cleaning bottles . Many of the bottle coatings now used are " applied ceramic labels" , that is, they are applied as inorganic frits which are then exposed to high temperatures. Applied ceramic labels, however, suffer from one or more disadvantages, such as the presence of heavy metals, low gloss, low color brilliance, the necessity of using high temperatures to melt the frits after application, and often a requirement to subsequently reanneal the labeled bottles. Organic coatings have been used for bottle coatings, but resistances to abrasion and impact of many of these coatings are typically low, and resistances to degredation by caustic bottle-cleaning solutions have often also been low. Organic coatings based primarily on epoxy resins, dicyandiamide curing agent, and reactive siloxane, and usually containing various additional components, are known. See, for example, the following United States patents: US 3,468,835, US 3,471,312, US 3,607,349, US 5,346,933, and US 5,411,768. The Invention A new crosslinking composition has now been found which permits many organic coatings applied to ceramic substrates to achieve high organic-organic and organic-ceramic bonding, as evidenced by high resistances to abrasion and impact. In most instances resistances of the organic coatings to degredation by caustic bottle-cleaning solutions is also high. Accordingly one embodiment of the invention is a crosslinking composition comprising: (a) amino-functional curing agent; (b) blocked polyisocyanate; and, optionally, (c) organo- functional siloxane comprising a member selected from the group consisting of epoxy-functional siloxane, amino- functional siloxane, (blocked isocyanato) -functional siloxane, and a mixture of two or more thereof. Another embodiment of the invention is a composition which may be used for coating, said composition comprising: (a) reactive organic resin which is polyhydroxy- functional, polyepoxy- functional , or both epoxy-functional and hydroxy- functional; (b) color- imparting pigment; (c) reactive wax; and (d) crosslinking composition comprising: (1) amino- functional curing agent; (2) blocked polyisocyanate; and, optionally, (3) organo-functional siloxane comprising a member selected frorr. the group consisting of epoxy-functional siloxane, amino- functional siloxane, (blocked isocyanato) -functional siloxane, and a mixture of two or more thereof. Yet another embodiment is an article comprising a ceramic substrate having thereon at least one coating of the above composition which has been crosslinked. For purposes of the present invention, inks are considered to be coating compositions. The amino- functional curing agents are themselves kn<~*-m curing agents for epoxy resins. Such amino- functional curing agents are reasonably shelf stable at ambient room temperatures, and sufficiently stable at application temperatures so that it does not unduly shorten the pot life of the coating composition in which the crosslinking composition is employed. " Pot life" is the length of time the coating will remain fluid enough to apply to substrates at application temperatures. Illustrative amino- functional curing agents which may be used include melamine, 2 , 4 , 6-tris (alkoxycarbonylamino) - 1, 3 , 5-triazine (also known as " TACT" ) where each alkoxy independently contains from 1 to 4 carbon atoms, and compounds represented by the formula: R- R. R. / N- -N R. R wherein: R 1( R 2 , R 3 each independently represents hydrogen, alkyl containing from 1 to 3 carbon atoms, or hydroxyalkyl containing from 1 to 3 carbon atoms, R 4 represents hydrogen, phenyl , cyano, acetyl, or R R, / ■ N R R 5 represents O, S, or NH, and R 6 and R 7 each independently represents hydrogen, alkyl containing from 1 to 3 carbon atoms, hydroxyalkyl containing from 1 to 3 carbon atoms, or phenyl . When any of R 1# R 2 , R 3 , R 6 , and R 7 is alkyl containing from 1 to 3 carbon atoms, it is independently methyl, ethyl, propyl, or isopropyl. The alkyl groups may be the same or some may be different from the others. The preferred alkyl group is methyl. When any of R lr R 2 , R 3 , R 6 , and R 7 is hydroxyalkyl containing from 1 to 3 carbon atoms, it usually is independently hydroxymethyl , hydroxyethyl , or hydroxypropyl . The hydroxyalkyl groups may be the same or some may be different from the others. The preferred hydroxyalkyl group is hydroxymethyl. Preferably, all of R 1 R 2 , R 3 , R 6 , and R 7 are hydrogen . Examples of suitable amino- functional curing agents include melamine [CAS 108-78-1], 2,4,6- tris (methoxycarbonylamino) -1, 3, 5-triazine [CAS 150986-36-0], 2, 4, 6-tris (butoxycarbonylamino) -1,3, 5-triazine [CAS 150986-45-1] , dicyandiamide [CAS 461-58-5] , 1, 3-diphenylguanidine [CAS 102-06-7], urea [CAS 57-13-6], thiourea [CAS 62-56-6] , acetylurea [CAS 591-07-1] , biguanide [CAS 56-03-1] , heptamethylbiguanide [CAS ..1446-22-9] , 2-ethyl- 4-methylimidazole [CAS 931-36-2] , and diaminodiphenyl sulfone [CAS 80-08-0] . The amino-functional curing agent may comprise one amino-functional curing agent or it may comprise a mixture of two or more amino- functional curing agents. Organic isocyanates react with organic compounds containing at least one " active hydrogen" , i.e., a hydrogen atom replaceable by sodium. Substantially all organic compounds containing a hydrogen atom attr -hed to oxygen or nitrogen will react with isocyanates under the proper conditions. An organic compound containing active hydrogen is suitable as a blocking agent if the product of its reaction with an isocyanate is unreactive with hydroxyl, amino, amido, ureylene, carbamyl, carbamyloxy, or other groups containing active hydrogen at room temperature, but reacts, by intermediate unblocking or otherwise, with one or more such groups of other compounds at an elevated temperature, usually in the range of from 90°C to 325°C, to form desired products. The reaction product of a blocking agent and an isocyanate is known as a " blocked isocyanate" . Although it is not desired to be bound by any theory, it is believed that the reaction to form the blocked isocyanate is reversed at the elevated temperature to regenerate isocyanato-functionality which then reacts with other compounds containing active hydrogen to form the desired products. In most instances the blocking agent contains active hydrogen attached to an oxygen atom or a nitrogen atom. Any suitable aliphatic, cycloaliphatic, aromatic- alkyl monoalcohol or phenolic compound may be used as a blocking agent in accordance with the present invention. Examples include but are by no means limited to methyl alcohol, ethyl alcohol, chloroethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, 3 , 3 , 5-trimethylhexanol, decyl alcohol, lauryl alcohol, cyclopentanol, cyclohexanol , phenylcarbinol, methylphenylcarbinol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, tert-butylphenol , 2 , 5-di-tert-butyl-4-hydroxytoluene, tertiary hydroxylamines such as diethylethanolamine, oximes such as methyl ethyl ketone oximes, acetone oxime, 2-butanone oxime and cyclohexanone oxime . Any suitable compound containing amine, amide, urea, urethane, or other groups having an active hydrogen attached to a nitrogen atom may be used. Examples of such compounds include, but are not limited to, dibutylamine, morpholine, 3-aminoproyl morpholine, diisopropylamine, 2-phenylimidazoline, benzotriazole, benzyl methacrylohydroxamate , 2-pyrolidone and ε-caprolactam. Polyfunctional blocking agents may be used when desired. Examples include, but are not limited to ethylene glycol, propropylene glycol, poly (ethylene glycol), poly (propylene glycol) , Pluronic type polypropylene, poly (tetrahydrofuran) , trimethylolpropane, ethoxylated trimethylolpropane, and poly (vinyl alcohol) . Procedures for blocking isocyanato groups are well known in the art . Blocking is often accomplished by reacting the isocyanato groups of the isocyanato-functional compound with blocking agent at temperatures in the range of from 25 °C to 120°C, although other temperatures may often be used. The organic blocked isocyanate is formed by reacting a sufficient quantity of blocking agent with the organic polyisocyanate to insure that substantially no unreacted isocyanato groups are present in the product . It should be noted that blocked isocyanato functionality does not contain the isocyanato group; rather it contains a group which is the reaction product of the isocyanato group and the blocking agent. For example, an isocyanato group blocked with an alcohol contains a urethane group, while an isocyanato group blocked with a primary or secondary amine contains a urea group. In the preparation of the blocked organic polyisocyanat" r , any suitable organic polyisocyanate may be used. Examples of classes of organic polyisocyanates include, but are not limited to, the aliphatic polyisocyanates, the cycloaliphatic polyisocyanates, the aliphatic-cycloaliphatic polyisocyanates, the aromatic polyisocyanates, the aliphatic- aromatic polyisocyanates, the uretedione polyisocyanates, and the biuret polyisocyanates . The polyisocyanates may be diisocyanates, triisocyanates, tetraisocyanstes or higher order isocyanates. Only one polyisocyanate or a mixture of two -or more polyisocyanates may be used. When mixtures are used, the constituent polyisocyanates may be from the same class or from different classes. Representative examples of suitable polyisocyanates which may be blocked include, but are not limited to: 1, 2-diisocyanatopropane, 1, 3-diisocyanatopropane, 1 , 2 -diisocyanato-2 -methylpropane , 1, 2-diisocyanatobutane, 1, 3-diisocyanatobutane, 1, 4-diisocyanatobutane, 2, 3-diisocyanatobutane, 1, 5-diisocyanatopentane, 1, 6-diisocyanatohexane, ethylidine diisocyanate, butylidene diisocyanate, 1, 2-diisocyanatocyclopentane, 1 , 3 -diisocyanatocyclopentane , 1, 2-diisocyanatocyclohexane, 1 , 3 -diisocyanatocyclohexane , 1 , 4 -diisocyanatocyclohexane , bis (4-isocyanatocyclohexyl) ether, 1- (isocyanatomethyl) -5-isocyanato-l, 3 , 3-trimethylcyclohexane, 1- (isocyanatomethyl) -1- (3-isocyanatopropyl) cyclohexane, bis (4-isocyanatocyclohexyl) methane, 1 , 2 -diisocyanatobenzene , 1, 3 -diisocyanatobenzene, 1, 4 -diisocyanatobenzene, 4,4' -diisocyanatobiphenyl , 1, 4-diisocyanatonaphthalene, 1, 5-diisocyanatonaphthalene, bis (4 -isocyanatophenyl) methane, 2 , 4 -diisocyanatotoluene , 2 , 6 -diisocyanatotoluene, 1,3 -bis (isocyanatomethyl) benzene, 1 , 4 -bis (isocyanatomethyl) benzene, bis (4 -isocyanatophenyl) ether, 3,3' -diisocyanatobiphenyl , 4,4' -diisocyanatobiphenyl , 4,4' -diisocyanato-2 , 2' -dimethylbiphenyl, 4,4' -diisocyanato-3 , 3 ' -dimethylbiphenyl, 4,4' -diisocyanato-2, 2' -dimethoxybiphenyl, 4,4' -diisocyanato-3 , 3 ' -dimethoxybiphenyl, tris (4 -isocyanatophenyl) methane, tris (4-isocyanatocyclohexyl) methane, 1,3, 5-triisocyanatobenzene, 2,4, 6 -triisocyanatotoluene , bis (2 , 5-diisocyanato-4-methylphenyl)methane, bis (2 , 5-diisocyanato-4-methylcyclohexyl) methane, 2,4, 6-triisocyanatσ-l, 3 , 5-triazine , N,N' -diisocyanatobiuret, N,N,N' -triisocyanatobiuret , N, N, N' ' -tetraisocyanobiuret , N,N' , " -tris (6-isocyanatohexyl) biuret , 2, 3 -bis (8-isocyanatooctyl) -4-octyl-5-hexylcyclohexene, polymeric polyisocyanates such as dimers and trimers, and prepolymers which are derived from a polyol, including a hydrocarbon polyol, a polyether polyol, and a polyest .- polyol. An example is an adduct (approximately 3:1, molar) of l-isocyanatomethyl-5-isocyanato-l, 3 , 3-trimethylcyclohexane [CAS 4098-71-9] and 1, 1 , 1-trimethylolpropane [CAS 77-99-6] . The optional organo- functional siloxane which may be employed in the crosslinking composition comprises a member selected from the group consisting of epoxy-functional siloxane, amino- functional siloxane, (blocked isocyanato) -functional siloxane, and a mixture of two or more thereof. The presence of the organo-functional siloxane in the crosslinking composition improves the adhesion of the coating composition to the substrate. Usually, but not necessarily, the epoxy-functional siloxane comprises a member selected from the group consisting of: (ω- (glycidyloxy) alkyl) trialkoxysilane, (ω- (glycidyloxy) alkyl) dialkoxyalkylsilane, (ω- (glycidyloxy) alkyl) alkoxydialkylsilane, (ω- (3 , 4-epoxycyclohexyl) alkyl) trialkoxysilane, and a mixture of two or more thereof . Examples of suitable epoxy-functional siloxanes include : (2- (glycidyloxy) ethyl) dimethoxymethylsilane [CAS 171609-54-4], (2- (glycidyloxy) ethyl) trimethoxysilane [CAS 20526-39-0], (2- (glycidyloxy) ethyl) triethoxysilane [CAS 56325-91-8], (3- (glycidyloxy) propyl) methoxydimethylsilane [CAS 100303-57-9], (3- (glycidyloxy) propyl) dimethoxymethylsilane [CAS 65799-47-5], (3- (glycidyloxy) propyl ) ethoxydimethylsilane [CAS 17963-04-1] , (3- (glycidyloxy) propyl) diethoxymethylsilane [CAS 2897-60-1], (3- (glycidyloxy) propyl) trimethoxysilane [CAS 2530-83-8], (3- (glycidyloxy) propyl) diethoxyethylsilane [CAS 99388-21-3], (3- (glycidyloxy) propyl) triethoxysilane [CAS 2602-34-8], (2- (3 , 4-epoxycyclohexyl) ethyl) trimethoxysilane [CAS 3388-04-3], (2- (3 , 4-epoxycyclohexyl) ethy , triethoxysilane [CAS 10217-34-2] , (3- (3 , 4-epoxycyclohexyl) propyl) trimethoxysilane [CAS 33684-79-6] , and (3- (3 , 4-epoxycyclohexyl) propyl) triethoxysilane [CAS 156183-90-3] . Only one epoxy-functional siloxane or a mixture of two or more epoxy-functional siloxanes may be used when desired. Usually, but not necessarily, the amino-functional siloxane comprises a member selected from the group consisting of: (co-aminoalkyl) trialkoxysilane, (ω-aminoalkyl) dialkoxyalkylsilane, (co-aminoalkyl) alkoxydialkylsilane, and a mixture of two or more thereof . Examples of suitable amino-functional silanes include : (2-aminoethyl)dimethoxymethylsilane [CAS 115599-33-2], (2-aminoethyl) trimethoxysilane [CAS 65644-31-7], ( 2 -aminoethyl) triethoxysilane [CAS 45074-31-5], (3-aminopropyl)methoxydimethylsilane [CAS 31024-26-7], (3-aminopropyl) dimethoxymethylsilane [CAS 3663-44-3], (3-aminopropyl) ethoxydimethylsilane [CAS 18306-79-1], (3-aminopropyl) diethoxymethylsilane [CAS 3179-76-8], (3-aminopropyl) trimethoxysilane [CAS 13822-56-5], (3-aminopropyl) diethoxyethylsilane [CAS 20723-29-9], and (3-aminopropyl) triethoxysilane [CAS 919-30-2]. Only one amino-functional siloxane or a mixture of two or more amino-functional siloxanes may be used when desired. Isocyanato groups of isocyanato-functional siloxanes may be reacted with blocking agents to form (blocked isocyanato) -functional siloxanes. The principles, blocking agents, and blocking procedures are substantially the same as those described above in respect of the formation of blocked polyisocyanates . Usually, but not necessarily, the (blocked isocyanato) -functional siloxane comprise a member selected from the group consisting of: ( (blocked isocyanato) alkyl ) trialkoxysilane , ((blocked isocyanato) alkyl) dialkoxyalkylsilane, ( (blocked isocyanato) alkyl) alkoxydialkylsilane, and a mixture of two or more thereof . Preferably the (blocked isocyanato) -functional siloxane comprises a member selected from the group consisting of : (co- (blocked isocyanato) alkyl) trialkoxysilane, (ω- (blocked isocyanato) alkyl) dialkoxyalkylsilane, (ω- (blocked isocyanato) alkyl) alkoxydialkylsilane, and a mixture of two or more thereof . Examples of suitable isocyanato-functional siloxanes which may be blocked include: (3 -isocyanatopropyl) trimethoxysilane [CAS 15396-00-6], (3 -isocyanatopropyl) diethoxyethylsilane [CAS 119262-02-1], and (3 -isocyanatopropyl) triethoxysilane [CAS 24801-88-5] . The (blocked isocyanato) -functional siloxanes corresponding to these exemplary isocyanato-functional siloxanes are: (3- (blocked isocyanato) propyl) trimethoxysilane, (3- (blocked isocyanato) propyl) diethoxyethylsilane, and (3- (blocked isocyanato) propyl) triethoxysilane . Only one (blocked isocyanato) -functional siloxane or a mixture of two or more (blocked isocyanato) -functional siloxanes may be used when desired. The crosslinking composition may be formed by admixing the components at temperatures below those which would cause significant reaction. The relative proportions of the components of the crosslinking composition may be widely varied. The amino-functional curing agent usually constitutes from 10 to 70 percent by weight of the crosslinking composition. Often the amino-functional curing agent constitutes from 20 to 50 percent by weight of the crosslinking composition. From 25 to 35 percent by weight of the crosslinking composition is preferred. The blocked polyisocyanate ordinarily constitutes from 2 to 80 percent by weight of the crosslinking composition. Frequently the blocked polyisocyanate constitutes from 5 to 75 percent by weight of the crosslinking composition. From 10 to 65 percent by weight of the crosslinking composition is preferred. The organo- functional siloxane may constitute from 0 to 70 percent by weight and usually constitutes from 5 to 70 percent by weight of the crosslinking composition. In many instances the organo- functional siloxane constitutes from 8 to 65 percent by weight of the crosslinking composition. From 10 to 60 percent by weight of the crosslinking composition is preferred when the siloxane is present. The reactive organic resin which is polyhydroxy- functional and which may be used in the coating composition of the invention may be widely varied. A class of polyhydroxy- functional reactive organic resin which is frequently employed comprises the polyhydroxy- functional polyester resins. As used herein and in the claims, the term " polyhydroxy- functional" means that on a number average molecular weight basis, the polyester contains on average, more than one hydroxyl group per molecule . Preferably the polyester contains, on average, at least two hydroxyl groups per molecule. The polyhydroxy- functional polyester resins which can be used in the present invention are numerous and widely varied. Such polyhydroxy- functional polyesters are preferably polyhydroxy-functional substantially saturated polyester resins, as that term is customarily understood in the industry. As used herein and in the claims, the term " saturated polyester" is intended to include polyesters containing aromatic unsaturation since aromatic unsaturation is generally unreactive in polyesters. Nevertheless, some ethylenic unsaturation may be present when circumstances warrant. Ethylenic unsaturation, when present, is often introduced by employing a small amount of ethylenically unsaturated acid such as maleic acid or fumaric acid, during preparation of the polyester. Usually less than 10 mole percent of the acids used to prepare the hydroxy- functional polyesters employed in the present invention are ethylenically unsaturated acids . Often less than 5 mole percent of the acids used to prepare the hydroxy- functional polyesters are ethylenically unsaturated acids. Preferably the ethylenically unsaturated acids are substantially absent. The polyhydroxy-functional polyesters may be produced from one or more polyolε and one or more pol carboxylic acids using well-known polycondensation procedures employing an excess of polyol to obtain a polymer having the desired proportion of hydroxyl groups. Examples of such procedures include, but are not limited to, direct esterification of polycarboxylic acid (or its anhydride if such anhydride exists) with polyol, transesteresterification, and reaction between polycarboxylic acid halide and the polyol. Notwithstanding the method of preparation used, it is convenient to classify polyhydroxy-functional polyesters according to the polyols and polycarboxylic acids which were used in direct esterification, or which would be used in a theoretical direct esterification. The polyols which can be used are numerous and widely varied. They are often aliphatic alicyclic, aromatic, aliphatic-alicyclic, aliphatic-aromatic, alicyclic-aromatic, or aliphatic-alicyclic-aromatic in nature. Usually the polyols contain from 2 to 20 carbon atoms. Frequently the polyols contain from 2 to 12 carbon atoms. The polyols are usually predominately diols. In most instances diols constitute at least 90 mole percent of the polyols. Often diols constitute at least 95 mole percent of the polyols. At least 98 mole percent is preferred. Frequently diols constitute all of the polyols. Examples of suitable diols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, 1, 3-propanediol , dipropylene glycol, trimethylene glycol, 2 , 4-dimethyl-2-ethylhexane-l, 3-diol, 2 , 2-dimethylpropane-l, 3-diol, 2-ethyl-2-butylpropane-l, 3-diol, 2 -ethyl -2 -isobutylpropane-1, 3-diol, 1, 3-butanediol, 1, 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, thiodiethanol , 1, 2-cyclohexanediol , 1, 3-cyclohexanediol, 1, 4-cyclohexanediol, 1, 2-cyclohexanedimethanol, 1,3- cyclohexanedimethanol , 1,4- cyclohexanedimethanol , 2 , 2, 4, 4-tetramethylcyclobutane-l, 3-diol, 1, 4-xylylenediol , 3-hydroxy-2 , 2-dimethylpropyl 3-hydroxy-2 , 2-dimethylpropanoate, 4,4'- (l-methylethylidene)bis [cyclohexanol] , and 4, 4 ' - (l-methylethylidene)bis [phenol] . A minor amount, that is, up to 10 mole percent of the polyol may be triol, tetrol, or higher functional polyol. Examples include, but are not limited to, glycerol, 1, 1, 1-trimethylolethane, 1, 1, 1- rimethylolpropane, erythritol, pentaerythritol, dipentaerythritol, sorbitol, mannitol, α-methylglucoside, and sorbitan. The polycarboxylic acids which can be used are also numerous and widely varied. They are often aliphatic, alicyclic, aromatic, aliphatic-alicyclic, aliphatic -aromatic, alicyclic-aromatic, or aliphatic-alic :lic-aromatic in nature. Usually they contain from 4 to 20 carbon atoms. The polycarboxylic acids are usually predominately dicarboxylic acids. In most instances dicarboxylic acids constitute at least 90 mole percent of the polycarboxylic acids. Often dicarboxylic acids constitute at least 95 mole percent of the polycarboxylic acids. At least 98 mole percent is preferred. Frequently dicarboxylic acids constitute all of the polycarboxylic acids. Examples of suitable dicarboxylic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, phthalic acid, isophthalic acid, terephthalic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 4-cyclohexanedicarboxylic acid. A minor amount, that is, up to 10 mole percent of the polycarboxylic acid may be tricarboxylic acid or higher functional polycarboxylic acid. Examples include, but are not limited to, trimellitic acid and 1, 2 , 3-propanetrioic acid. The hydroxy-functionality of the polyhydroxy- functional polyester resins which are used in the present invention is conveniently characterized by the hydroxyl number, which is well known and may be determined according to the procedure of ASTM E 222-94, the entire disclosure of which is incorporated herein by reference. Usually the polyhydroxy- functional polyester resins have a hydroxyl number of at least 5. In many instances the hydroxyl number is in the range of from 5 to 200. The number average molecular weight of the polyhydroxy-functional polyester resin is usually in the range of from 500 to 10,000, although lower or higher number average molecular weights may be used when desired. As used herein, number average molecular weights are determined by gel permeation c^romatography using polystyrene standards. The inherent viscosity (logarithmic-viscosity number) of the polyhydroxy-functional polyester resin is often in the range of from 0.1 to 0.5 deciliters/gram, as described in Chemical Engineers Handbook, 5th Edition, 1973. Lower or higher inherent viscosities can be used when desired. In most instances the polyhydroxy- functional polyester resin used in the present invention is semi-crystalline, that is, the polyester has a discernible crystallization or melting point by differential scanning calorimetry (DSC) . Nevertheless the polyhydroxy- functional polyester resin used in the present invention may be amorphous, that is the polyester exhibits no, or only a trace of, crystallization or melting point as determined by differential scanning calorimetry. The polyepoxy- functional reactive organic resin which may be used in the coating composition of the invention may also be widely varied. As used herein and in the claims, the term " polyepoxy- functional" means that on a number average molecular weight basis, the resin contains on average, more than one epoxy group per molecule. Preferably the resin contains, on average, at least two hydroxyl groups per molecule. Of particular interest are the polyglycidyl ethers of polyhydric alcohols. Useful polyglycidyl ethers of polyhydric alcohols can be formed by reacting epihalohydrins, such as epichlorohydrin [CAS 106-89-8] , with polyhydric alcohols, especially dihydric alcohols, in the presence of an alkali condensation and dehydrohalogenation catalyst such as sodium hydroxide or potassium hydroxide. Inasmuch as phenolic hydroxyls react with epichlorohydrin in much the same way as aliphatic alcoholic hydroxyls, compounds having at least two phenolic hydroxyls are, for purposes of the present discussion, regarded as polyhydric alcohols. Suitable polyhydric alcohols can be aromatic, aliphatic or cycloaliphatic . Examples of suitable aliphatic polyhydric alcohols include, but are not limited to, aliphatic dihydric alcohols such as : ethylene glycol [CAS 107-21-1] , neopentyl glycol [CAS 126-30-7] , diethylene glycol [CAS 111-46-6] , triethylene glycol [CAS 112-27-6] , tetraethylene glycol [CAS 112-60-7] , dipropylene glycol [CAS 110-98-5] , 1,2-propanediol [CAS 57-55-6], 1,3-propanediol [CAS 504-63-2], 1,2-butanediol [CAS 26171-83-5], 1,3-butanediol [CAS 107-88-0], 2,3-butanediol [CAS 513-85-9], 1,4-butanediol [CAS 110-63-4], 1,2-pentanediol [CAS 5343-92-0], 1, 4-pentanediol [CAS 626-95-9], 2, 4-pentanediol [CAS 625-69-4], 1, 5-pentanediol [CAS 111-29-5], 1, 6-hexanediol [CAS 629-11-8], 3 -hydroxy-2 , 2-dimethylpropyl 3 -hydroxy-2, 2-dimethylpropanoate [Ester Diol 204; CAS 1115-20-4], poly(ethylene oxide) [CAS 25322-68-3], and poly (propylene oxide) [CAS 25322-69-4] . Examples of suitable aliphatic polyhydric alcohols having more than two alcoholic hydroxyl groups include, but are not limited to: sorbitol [CAS 50-70-4] , mannitol [CAS 69-65-8] , glycerol [CAS 56-81-5] , 1,2, 6-hexanetriol [CAS 106-69-4], erythritol [CAS 149-32-6] , pentaerythritol [CAS 115-77-5] , dipentaerythritol [CAS 126-58-9] , tripentaerythritol [CAS 78-24-0] , 1, 1, 1-trimethylolethane [CAS 77-85-0], and 1, 1, 1-trimethylolpropane [CAS 77-99-6]. Examples of suitable aromatic polyhydric alcohols include : pyrocatechol [CAS 120-80-9] , resorcinol [CAS 108-46-3] , hydroquinone [CAS 123-31-9] , 4 , 4 ' - (1-methylethylidene) bis [phenol] [bisphenol A; CAS 80-05-7] , 4,4'- (1-methylethylidene) ) bis [2 , 6-dibromophenol] [tetrabromobisphenol A; CAS 79-94-7] , 4,4'- (1-methylethylidene) ) bis [2 , 6-dichlorophenol] [tetrachlorobisphenol A; CAS 79-95-8] , 4, 4 ' - (l-methylpropylidene)bis [phenol] [bisphenol B; CAS 77-40-7] , 4,4'- (1-methylethylidene) bis (2-methylphenol] [bisphenol C; CAS 79-97-0] , 4,4 '- (1, 2 -ethanediyl) bis [phenol] [bisphenol E; CAS 6052-84-2], 2,2 ' -methylenebis [phenol] [bisphenol F; CAS 2467-02-9), 4,4'- (1-methylethylidene) bis [2- (1-methylethvl) phenol] [bisphenol G; CAS 127-54-8] , 4 , 4 ' - [1, 3-phenylenebis (1-methylethylidene) ] bis [phenol] [bisphenol M; CAS 13595-25-0] , 4 , 4 ' - [1, 4-phenylenebis (1-methylethylidene) ] bis [phenol] [bisphenol P; CAS 2167-51-3] , 4, 4 ' -sulfonylbis [phenol] [bisphenol S; CAS 80-09-1], 4 , 4 ' -cyclohexylidenebis [phenol] [bisphenol Z; CAS 843-55-0], 4, 4 ' - (2, 4, 8, 10-tetraoxaspiro [5.5] undecane-3 , 9-diyldi-2, 1- ethanediyl) bis [phenol] [bisphenol PA; '.AS 3616-75-9], 4 , 4 ' - (l-phenylethylidene)bis [phenol] [bisphenol ACP; CAS 1571-75-1] , 4,4 ' -methylenebis [phenol] [HDM; CAS 620-92-8], 2,2' -methylenebis [4-methyl-6- (1-methylethyl) phenol] [bisphenol 2246; CAS 24742-47-0], 3 , 3-bis (4-hydroxypheny1) -1 (3H) -isobenzofuranone [phenolphthalein; CAS 77-09-8] , 4,4 ■ -ethylidenebis [phenol] [CAS 2081-08-5], 4,4 ' -propylidenebis [phenol] [CAS 1576-13-2], 4,4 '- (1-ethylpropylidene) bis [phenol] [CAS 3600-64-4], 4,4 '- (1,4-cyclohexanediyl) bis [phenol] [CAS 10466-91-8], 4,4' - (1,3-cyclohexanediyl) bis [phenol] [CAS 55418-36-5], 4,4' - (1,2-cyclohexanediyl) bis [phenol] [CAS 55418-39-8], 4,4' - (phenylmethylene) bis [phenol] [CAS 4081-02-1], 4, 4 ' - (2, 2, 2-trichloroethylidene)bis [phenol] [hydroxychlor; CAS 2971-36-0] , 4-hydroxy-a- (4-hydroxyphenyl)benzeneacetic acid, butyl ester [CAS 71077-33-3] , 4,4'- (diphenylmethylene) bis [phenol] [bisphenol TP; CAS 1844-01-5] , 4,4 ' -thiobis [phenol] [CAS 2664-63-3], 1, 2-dihydroxynaphthalene [CAS 574-00-5], 1, 3-dihydroxynaphthalene [CAS 132-86-5], 1, 4-dihydroxynapht_-.alene [CAS 571-60-8], 1, 5-dihydroxynaphthalene [CAS 83-56-7], 1,1, 3 -tris (4 -hydroxypheny1) propane, phenol-formaldehyde novolac, and o-cresol-formaldehyde novolac. Many ethylene oxide or propylene oxide extended aromatic polyhydric alcohols are known and may be used when desired. Examples of suitable cycloaliphatic polyhydric alcohols include, Hut are not limited to: 1, 2-cyclohexanediol [CAS 931-17-9], 1,3-cyclohexanediol [CAS 504-01-8], 1,4-cyclohexanediol [CAS 556-48-9], 1,2-cyclohexanedimethanol [CAS 3971-29-7], 1,3 -cyclohexanedimethanol [CAS 3971-28-6], 1, 4-cyclohexanedimethanol [CAS 105-08-8], 4,4 ' - (1-methylethylidene) bis [cyclohexanol] [hydrogenated bisphenol A; CAS 80-05-7] . Another useful class of polyepoxy-functional resins containing at least two epoxy groups per molecule, are those containing, on average, at least one epoxycycloaliphatic group per molecule. These resins may be made by epoxidation of the cycloalkene group using a peracid such as peracetic acid. An example of a resin that contains one epoxycycloalkyl group and a pendent epoxy group is 1- (epoxyethyl) -3 , 4-epoxycyclohexane [CAS 106-87-6]. Examples of epoxy-functional resins containing two or more epoxycycloalkyl groups include, but are not limited to: bis (2,3-epoxycyclopentyl) ether [CAS 2386-90-5], 3 , 4-epoxycyclohexylmethyl 3 ' , 4 ' -epoxycyclohexanecarboxylate [CAS 2386-87-0] , bis (3, 4-epoxycyclohexyl ) adipate [CAS 83996-66-1], and bis (3 , 4-epcxycyclohexylmethyl) 4 , 5-epoxycyclohexane- 1,2-dicarboxylate [CAS 21678-82-0]. Poly(primary amino) -functional and poly (secondary amino) -functional compounds may be used to chain-extend the polyepoxy-functional resins. Suitable polyepoxy-functional resins usually have an epoxide equivalent weight (i.e., molecular weight of resin per epoxide group) in the range of from 100 to 4000, as measured by titration with perchloric acid using methyl violet as an indicator. Often the polyepoxy- functional resins have an epoxide equivalent weight in the range of from 170 to 700. Preferably the epoxide equivalent weight is in the range of from 250 to 600. Other useful polyepoxides are disclosed in U.S. Patent No. 5,820,987 at column 4, line 52 through column 6, line 59. The disclosure of U.S. Patent No. 5,820,987 is, in its entirety, incorporated herein by reference. Many of the polyepoxy-functional organic resins formed by reacting diols with epichlorohydrin also contain polyhydroxy-functionality. In the case of reaction of bisphenol A with epichlorohydrin, ideal reaction products having number average molecular weights of greater than 624 theoretically have, on average, two epoxy groups and more than one hydroxyl group per molecule. Examples of suitable commercially available polyepoxy-functional and polyhydroxy-functional resins are Epon® 828, 836, and 880 epoxy resins. If the number average molecular weight is 908 or greater, ideal reaction products of bisphenol A and epichlorohydrin theoetically have, on average, two epoxy groups and at least two hydroxyl group per molecule. Examples of such polyepoxy- functional and polyhydroxy- functional resins which are commercially available are Epon® 1001F, 1002, 1004, 1007, and 1009. The Epon® resins are available from Shell Chemicals Co., Houston, TX, USA. The polyepoxy-functional resin may be reacted with various terminating agents, as for example amino-functional siloxane, to convert some, or even all, of the terminal epoxy groups to terminal groups of other functionality. In most instances, the consumption of the epoxy groups during the termination reaction is accompanied by the generation of hydroxy groups on the resin. Color-imparting pigments used in formulating the coating compositions of the present invention are f._:ely divided solid powders, insoluble but wettable under the conditions of use. They confer substantial color (which includes white, black and grey) to the coating compositions of the invention and to coatings formed from such coating compositions. Finely divided solid powders which do not impart substantial color to the coating compositions and to coatings formed therefrom are, for purposes of the present invention, considered not to be pigments, but rather, they are considered to be substantially colorless fillers. The color-imparting pigments may be widely varied. They may be organic or inorganic. It is preferred to use color-imparting pigments which do not contain heavy metals although some heavy metals such as copper which are not very toxic in the concentrations employed, may be present. In general it is preferred to use titanium dioxide as a white pigment and carbon in one of its forms as a black pigment, and to use organic pigments for imparting colors other than white, black, or grey. Examples of color-imparting pigments include, but are not limited to: Carbon Black Lampblack Furnace Black Thermal Decomposition Black Vegetable Black Animal Black Bone Black Impingement Carbon Black Graphite Rutile [CAS 1317-80-2] Anatase [CAS 1317-70-0] Clay Aluminum Hydroxide, Pigment Black 6 [CAS 1333-86-4] Pigment Black 7 [CAS 1333-86-4] Pigment Black 10 [CAS 7282-42-5] Pigment White 6 [CAS 13463-67-7] Pigment Blue 1 [CAS 1325-87-7] , Pigment Blue 15 [CAS 147-14-8] , Pigment Blue 19 [CAS 58569-23-6] , Pigment Blue 24 [CAS 6548-12-5] , Pigment Blue 60 [CAS 81-77-6] , Pigment Green 4 [CAS 61725-50-6] , Pigment Green 7 [CAS 1328-53-6] , Pigment Green 36 [CAS 14302-13-7] , Pigment Yellow 3 [CAS 6486-23-2] , Pigment Yellow 12 [CAS 6358-85-6] , Pigment Yellow 13 [CAS 5102-83-0] , Pigment Yellow 74 [CAS 6358-31-2] , Pigment Yellow 83 [CAS 5567-15-7] , Pigment Yellow 93 [CAS 5580-57-4] , Pigment Yellow 96 [CAS 5280-80-8] , Pigment Yellow 110 [CAS 5590-18-1] , Pigment Yellow 138 [CAS 56731-19-2] , Pigment Yellow 139 [CAS 36888-99-0] , Pigment Yellow 154 [CAS 63661-02-9] , Pigment Yellow 168 [CAS 71832-85-4] , Pigment Yellow 191 [CAS 125423-54-7] , Pigment Orange 5 [CAS 3468-63-1] , Pigment Orange 13 [CAS 3520-72-7] , Pigment Orange 36 [CAS 12236-62-3] , Pigment Orange 43 [CAS 4424-06-0] , Pigment Red 2 [CAS 6041-94-7] , Pigment Red 3 [CAS 2425-85-6] , Pigment Red 5 [CAS 6410-41-9] , Pigment Red 17 [CAS 6655-84-1] , Pigment Red 23 [CAS 6471-49-4] , Pigment Red 38 [CAS 6358-87-8] , Pigment Red 52 [CAS 17852-99-2] , Pigment Red 57 [CAS 5281-04-9] , Pigment Red 112 [CAS 6535-46-2] , Pigment Red 122 [CAS 980-26-7] , Pigment Red 123 [CAS 24108-89-2] , Pigment Red 144 [CAS 5280-78-4] , Pigment Red 170 [CAS 2786-76-7] , Pigment Red 177 [CAS 4051-63-2] , Pigment Red 179 [CAS 5521-31-3] , Pigment Red 202 [CAS 68859-50-7] , Pigment Red 254 [CAS 122390-98-1] , Pigment Violet 19 [CAS 1047-16-1] , and Pigment Violet 23 [CAS 6358-30-1] . Only one color- imparting pigment or a mixture of two or more color- imparting pigments may be used. Reactive waxes are long-chain aliphatic substances which have at least one reactive group having an active hydrogen, usually selected from hydroxyl, amido, ureylene, carbamyl, and carbamyloxy, and which have the physical characteristics commonly associated with waxes. The reactive waxes comprise many different classes of compounds. Examples of reactive waxes include normal primary alkanols having from 12 to 20 carbon atoms, normal primary amines having from 12 to 20 carbon atoms, normal saturated monocarboxylic acids having from 8 to 20 carbon atoms, and normal saturated monocarboxylic amides having from 8 to 20 carbon atoms. Although the normal (that is, straight chain) structures are preferred, some branching may be present, as for example isostearyl alcohol. Other examples of reactive waxes include the poly (ethylene oxides) having normal molecular weights of at least 1000, the poly (propylene oxides) having normal molecular weights of at least 5000; these may terminated with two hydroxyl groups or with one hydroxyl group and one lower alkoxy group. Saturated long chain aliphatic diols or saturated long chain dicarboxylic acids having waxy characteristics may also be used. While saturated compounds are preferred, a small amount of unsaturation may be present, as for example oleic acid. Similarly more than one reactive group may be in the molecule, as for example 12-hydroxystearic acid and sebacic acid. Of the reactive waxes, the normal primary alkanols having from 12 to 20 carbon atoms are preferred. Stearyl alcohol is especially preferred. The relative proportions of the components of the coating composition may be widely varied. The reactive organic resin which is polyhydroxy- functional, polyepoxy- functional, or both polyepoxy-functional and polyhydroxy- functional usually constitutes from 20 to 80 percent by weight of the coating composition. Often such reactive organic resin constitutes from 30 to 70 percent by weight of the coating composition. From 40 to 60 percent by weight of the coating composition is preferred. The color- imparting pigment ordinarily constitutes from 1 to 45 percent by weight of the coating composition. Frequently the color- imparting pigment constitutes from 3 to 40 percent by weight of the coating composition. From 5 to 35 percent by weight of the coating composition is preferred. The reactive wax usually constitutes from 0.1 to 20 percent by weight of the coating composition. In many instances the reactive wax constitutes from 0.5 to 15 percent by weight of the coating composition. From 1 to 10 percent by weight of the coating composition is preferred. The crosslinking composition usually constitutes from 1 to 20 percent by weight of the coating composition. In many instances the crosslinking composition constitutes from 2 to 18 percent by weight of the coating composition. From 3 to 16 percent by weight of the coating composition is preferred. Substantially colorless fillers are materials which may optionally be present in the coating composition. Such fillers are finely divided particulate solids which impart little or no color to the final coatings. The fillers usually have a maximum dimension of less than 500 nanometers. Often the fillers have a maximum dimension of less than 100 nanometers. Frequently the maximum dimension is less than 50 nanometers. In many instances the maximum dimension is less than 20 nanometers. Often the maximum dimension is in the range of from 5 to 20 nanometers. Preferably the fillers are hydrophobic. Examples of suitable hydrophobic fillers include Aerosil ® fumed silicas designated R972, R974, R812, R812S, R805 (Degussa Corporation, Ridgefield Park, NJ,USA) . Many other materials may be optionally present in the coating composition. Among these are included antioxidants, degassing aids, flow modifiers, sag control agents, viscosity agents and Fluorescent Whitening Agents. When present, these optional materials are usually present in the coating composition in their customary amounts for their customary purposes. In most instances the optional materials, when present, will constitute from 0.01 to 15 percent by weight of the coating composition. Often optional materialt , when present, will constitute from 0.01 to 10 percent by weight of the coating composition. The coating composition may be formed by admixing the ingredients at temperatures below those which would cause significant reaction. The coating compositions of the present invention can be applied directly to ceramic substrates and/or to one or more previously applied coatings of the same or similar coating compositions. Usually they are applied at elevate. " temperatures so that the chilling effect of the cooler substrate will quickly substantially solidify the coating. Such solidification is helpful in maintaining fine-line definition, in permitting application of multiple coatings without impairing the definition of any previously applied coating, and in permitting multiple coating while avoiding energy-inefficient crosslinking between coating applications. When multiple coatings are applied to the same area, it is advantageous for the application temperature of a subsequently applied coating to be lower than the temperature at which a previously applied coating will liquefy or unduly soften. This will enhance preservation of the fine- line definition and resolution of the previously applied coating. Since most of these coating compositions substantially instantly solidify to the touch after application, they can be advantageously used in coating lines operating at high speeds where bottles or other ceramic substrates are sequentially coated. After the coatings have been applied, the coated ceramic substrate is heated to elevated temperatures to cure, i.e., crosslink, the coatings. In the interests of completeness, it should be stated that the last applied coating may or may not be dry to the touch before the coatings are crosslinked at elevated tempera ures. As used herein and in the claims, " ceramic substrate" is used in its broadest sense, unless otherwise more restrictively qualified. Examples of ceramic substrates include, but are not limited to, unglazed pottery, glazed pottery, unglazed earthenware, glazed earthenware, unglazed porcelain, glazed porcelain, coffee cups, tea cups, wall tiles, Christmas tree ornaments, promotional ware, and glass substrates. Examples of glass substrates include, but are not limited to, window glass, automotiv glass, drinking glasses, glass bottles, glass jugs, glass jars, glass pitchers, and glass jewelry. Application of the coating compositions can be by any technique known to the art. Coating compositions which are applied at elevated temperatures because they are substantially solids at room temperature are usually applied using screen coating techniques. Coating compositions which are liquids at room temperature can be applied by spraying, curtain coating, roller application, printing, and brushing. These techniques are only exemplary; others may be used as desired. Curing of one or more of the applied coating compositions is accomplished at temperatures higher than those at which the polyisocyanates were blocked. In most instances the curing temperature is at least 150°C. The curing temperature should not be so high as to cause unwanted coloration or other thermal degredation of the coatings. Usually the curing temperature is in the range of from 150°C to 200°C. Unfortunately some crosslinking does occur at application temperatures and such crosslinking eventually causes the coating composition to thicken to the point it cannot be applied. A major problem with the prior coatings has been short pot life. Frequently the pot lives of the coating compositions of the present invention are longer than many of the coating compositions of the prior art. Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term " about" . The invention is further described in conjunction with the following examples which are to be considered illustrative rather than limiti j, and in which all parts are parts by weight and all percentages are percentages by weight unless otherwise specified. EXAMPLE 1 An additive mixture was formed by admixing the materials shown in Table 1: Table 1 Component Parts by weight Ti-Pure" 1 R-706 Titanium Dioxide Pigment (1) 271.8 Uvitex * OB Fluorescent Whitening Agent (2) 2.0 Tinuvin" ' 144 Antioxidant (3) 5.0 Tinuvin Φ 900 Antioxidant (4) 2.5 Modaflow" Flow Modifier (5) 10.0 Aluminum Hydroxide 10.0 NeoGen™ DGH Aluminum Silicate (6) 20.0 Benzoin 1.0 Total 322.3 (1) E.I. du Pont de Nemours & Co., Wilmington, DE, USA. (2) 2,2' - (2, 5-Thiophenediyl)bis (5- tert-butyl -benzoxazole) [CAS 7128-64-5]; Ciba-Geigy Corp., Houston, TX, USA. (3) [CAS 63843-89-0] Ciba Specialty Chemicals, Tarrytown, NY, USA. (4) [CAS 70321-86-7] Ciba Specialty Chemicals, Tarrytown, NY, USA. (5) Ethyl acrylate-co-2-ethylhexyl Acrylate polymer [CAS 26376-86-3] Monsanto Company, St. Louis, MO, USA. (6) Dry Branch Kaolin Co., Dry Branch, GA, USA. Epon 836 bisphenol A diglycidyl ether was warmed in an oven at 100°C. The materials shown in Table 2 were charged to a mixer and mixed at 100°C to give a clear liquid: Table 2 Component Parts by weight Warmed Epon" ' 836 bisphenol A diglycidyl ether (7) 200.0 Epon* 1001F bisphenol A diglycidyl ether (7) 300.0 Vestagon * blocked polyisocyanate (8) 21.2 Stearyl alcohol 36.0 Total 557.2 (7) [CAS 25068-38-6] Shell Chemicals Co., Houston, TX, USA. (8) Vestagon ® EP B 1400, believed to be an adduct of isophorone diisocyanate [CAS 4098-71-9] , 1, 1, 1-trimethylolpropane [CAS 77-99-6], and ε-caprolactam [CAS 105-60-2] in a 3:1:3 molar ratio, Hϋls America, Inc., Piscataway, NJ, USA. While the mixer was running, 14.9 parts of R974 hydrophobic fumed silica (Degussa Corp, Ridgefield, NJ, USA) and 322.3 parts of the above additive mixture of Table 1 were sequentially charged to the mixer. The charged materials were then mixed for one hour at 100°C to give a white liquid. Next 31.4 parts of Dyhard" 100S dicyandiamide (SKW Trostberg Aktiengesellschaft, Trostberg, Germany) was added and the mixture was mixed at 100°C for 10 minutes. Silquest * A-187™ (3- (glycidyloxy) propyl) trimethoxysilane (Witco Corp., Greenwich, CT, USA) in the amount of 55.60 parts was added and the mixture was mixed at 100°C for 5 minutes. The product, which was a white coating composition for printing bottles, was poured into an aluminum pan and allowed to cool to room temperature to produce a solid white coating composition. EXAMPLE 2 A first mixture was formed by admixing the materials shown in Table 3 at 130°C until all components were dissolved and the first mixture was homogeneous. Table 3 Component Parts by weight Epon * 8112 bisphenol A diglycidyl ether (9) 100.0 Vestagon* blocked polyisocyanate (10) 5.0 Total 105.0 (9) Shell Chemicals Co., Houston, TX, USA. (10) See Example 1, Table 2, note (8) . The materials shown in Table 4 were charged to a container and mixed at 100°C until homogeneous to provide a second mixture . Table 4 Component Parts by weight Irgazin 2029 Red Pigment (11) 10.5 Ti-Pure * R-706 Titanium Dioxide Pigment (12) 3.5 Modaflow * Flow Modifier (13) 1.3 BYK 405 (14) 0.8 Dyhard * 100M dicyandiamide (15) 4.5 Aerosil R974 (16) 2.0 Total 22.6 (11) Ciba Specialty Chemicals, Wilmington, DE, USA. (12) See Example 1, Table 1, note (1) . (13) See Example 1, Table 1, note (5) . (14) BYK-Chemie USA, Wallingford, CT, USA. (15) SKW Trostberg Aktiengesellschaft , Trostberg, Germany. (16) Degussa-Hύls Corporation, Ridgef .= Id Park, NJ, USA. A red coating composition was formed by adding 105.0 parts of the first mixture to the container containing 22.6 parts of the second mixture and admixing the materials well at 100°C. EXAMPLE 3 A portion of the white coating composition prepared in Example 1 was printed on a glass bottle using a standard pattern on a Strutz GP-4 Semi-Automatic General Purpose Decorator. A stainless steel screen of 230 mesh was used and the white coating composition was printed at temperatures in the range of from 105°C to 110°C. The white coating was substantially instantly dry to the touch on the printed bottle. A portion of the red coating composition prepared in Example 2 was substantially immediately printed as a design, partially on the dry white coating and partially on the glass bottle itself. The red coating composition was printed using a Strutz GP-4 Semi-Automatic General Purpose Decorator. A stainless steel screen of 200 mesh was used and the red coating composition was printed at 35°C. The printed bottle was cured in a forced air oven at 180°C for one hour. The resultant image was sharp, clear, and durable. Exposure to 10% caustic at 70°C for 24 hours caused no change in gloss or appearance. Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details should be regarded as limitations upon the scope of the invention except insofar as they are included in the accompanying claims.

Claims: Claims : 1. A crosslinking composition comprising: (a) amino-functional curing agent; (b) blocked polyisocyanate; and (c) optionally, an organo- functional siloxane comprising a member selected from the group consisting of epoxy-functional siloxane, amino-functional siloxane, (blocked isocyanato) -functional siloxane, and a mixture of two or more thereof . 2. The crosslinking composition of claim 1 wherein the amino-functional curing agent comprises a member selected from the group consisting of melamine, 2,4,6- tris (alkoxycarbonylamino) -1, 3 , 5-triazine where each alkoxy independently contains from 1 to 4 carbon atoms, a compound represented by the formula : R. R, R. wherein : Ri., R 2 , and R 3 each independently represents hydrogen, alkyl containing from 1 to 3 carbon atoms, or hydroxyalkyl containing from 1 to 3 carbon atoms, R 4 represents hydrogen, phenyl , cyano, acetyl, or • N R 7 R 5 represents 0, S, or NH, and R 6 and R 7 each independently represents hydrogen, alkyl containing from 1 to 3 carbon atoms , hydroxyalkyl containing from 1 to 3 carbon atoms, or phenyl, and a mixture of two or more thereof . 3. The crosslinking composition of claim 1 wherein the amino-functional curing agent comprises dicyandiamide . 4. The crosslinking composition of claim 1 wherein the blocked polyisocyanate comprises a member selected from the group consisting of blocked aliphatic polyisocyanate, blocked cycloaliphatic polyisocyanate, blocked aliphatic- cycloaliphatic polyisocyanate, blocked aromatic polyisocyanate, blocked aliphatic-aromatic polyisocyanate, blocked uretedione polyisocyanate, blocked biuret polyisocyanate, and a mixture thereof. 5. The crosslinking composition of claim 1 wherein the blocked polyisocyanate comprises an adduct of isophorone diisocyanate, 1, 1, 1-trimethylolpropane, and ε-caprolactam in a 3:1:3 molar ratio. 6. The crosslinking composition of claim 1 wherein the organo- functional siloxane is present and comprises τ.oxy- functional siloxane. 7. The crosslinking composition of claim 6 wherein the epoxy-functional siloxane comprises a member selected from the group consisting of : (glycidyloxyalkyl) trialkoxysilane, (glycidyloxyalkyl) dialkoxyalkylsilane, (glycidyloxyalkyl) alkoxydialkylsilane, (3 , 4-epoxycyclohexylalkyl) trialkoxysilane, and a mixture of two or more thereof . 8. The crosslinking composition of claim 6 wherein the epoxy-functional siloxane comprises a member selected from the group consisting of: (co- (glycidyloxy) alkyl) trialkoxysilane, (ω- (glycidyloxy) alkyl) dialkoxyalkylsilane, (ω- (glycidyloxy) alkyl) alkoxydialkylsilane, (ω- (3 , 4-epoxycyclohexyl) alkyl) trialkoxysilane, and a mixture of two or more thereof . 9. The crosslinking composition of claim 6 wherein the epoxy-functional siloxane comprises a member selected from the group consisting of: (2- (glycidyloxy) ethyl) dimethoxymethylsilane] , (2- (glycidyloxy) ethyl) trimethoxysilane, (2- (glycidyloxy) ethyl) triethoxysilane, (3- (glycidyloxy) propyl )methoxydimethylsilane, (3- (glycidyloxy) propyl) dimethoxymethylsilane, (3- (glycidyloxy) propyl) ethoxydimethylsilane, (3- (glycidyloxy) propyl) diethoxymethylsilane, (3- (glycidyloxy) propyl) trimethoxysilane, (3- (glycidyloxy) propyl) diethoxyethylsilane, (3- (glycidyloxy) propyl) triethoxysilane, (2- (3 , 4-epoxycyclohexyl) ethyl) trimethoxysilane, (2- (3 , 4-epoxycyclohexyl) ethyl) triethoxysilane, (3- (3, 4-epoxycyclohexyl) propyl) trimethoxysilane, (3- (3, 4-epoxycyclohexyl) propyl) triethoxysilane, and a mixture of two or more thereof . 10. The crosslinking composition of claim 6 wherein the epoxy-functional siloxane comprises (3- (glycidyloxy) propyl) trimethoxysilane . ll. The crosslinking composition of claim 1 wherein the organo- functional siloxane is present and comprises amino-functional siloxane. 12. The crosslinking composition of claim 11 wherein the amino-functional siloxane comprises a member selected from the group consisting of: (ω-aminoalkyl) trialkoxysilane, (co-aminoalkyl) dialkoxyalkylsilane, (ω-aminoalkyl) alkoxydialkylsilane, and a mixture of two or more thereof. 13. The crosslinking composition of claim 11 wherein the amino-functional siloxane comprises a member selected from the group consisting of (2-aminoethyl) dimethoxymethylsilane, (2-aminoethyl) trimethoxysilane, (2-aminoethyl) triethoxysilane, (3-aminopropyl)methoxydimethylsilane, (3-aminopropyl) dimethoxymethylsilane, (3-aminopropyl) ethoxydimethylsilane, ( 3-aminopropyl ) diethoxymethylsilane , (3 -aminopropyl) trimethoxysilane , (3 -aminopropyl ) diethoxyethylsilane , (3-aminopropyl) triethoxysilane and and a mixture of two or more thereof . 14. The crosslinking composition of claim 1 wherein the organo- functional siloxane is present and comprises (blocked isocyanato) -functional siloxane. 15. The crosslinking composition of claim 14 wherein the (blocked isocyanato) -functional siloxane comprises a member selected from the group consisting of: ( (blocked isocyanato) alkyl) trialkoxysilane, ( (blocked isocyanato) alkyl) dialkoxyalkylsilane, ( (blocked isocyanato) alkyl) alkoxydialkylsilane, and a mixture of two or more thereof . 16. The crosslinking composition of claim 14 wherein the (blocked isocyanato) -functional siloxane comprises a member selected from the group consisting of: (ω- (blocked isocyanato) alkyl) trialkoxysilane, (ω- (blocked isocyanato) alkyl) dialkoxyalkylsilane, (ω- (blocked isocyanato) alkyl) alkoxydialkylsilane, and a mixture of two or more thereof . 17. The crosslinking composition of claim 14 wherein the (blocked isocyanato) -functional siloxane comprises a member selected from the group consisting of: (3- (blocked isocyanato) propyl) trimethoxysilane, (3- (blocked isocyanato) propyl) diethoxyethylsilane, (3- (blocked isocyanato) propyl) triethoxysilane, and a mixture of two or more thereof. 18. The crosslinking composition of claim 3 wherein: (a) the dicyandiamide constitutes from 10 to 70 percent by weight of the crosslinking composition; (b) the blocked polyisocyanate constitutes from 2 to 80 percent by weight of the crosslinking composition; and (c) the organo- functional siloxane constitutes from 0 to 70 percent by weight of the crosslinking composition. 19. A composition which may be used for coating, said composition comprising: (a) reactive organic resin which is polyhydroxy- functional, polyepoxy- functional , or both epoxy-functional and hydroxy- functional ; (b) color- imparting pigment; (c) reactive wax; and (d) crosslinking composition of claim 1. 20. A composition which may be used for coating, said composition comprising: (a) reactive organic resin which is polyhydroxy- functional, polyepoxy- functional , or both epoxy-functional and hydroxy- functional ; (b) color- imparting pigment; (c) reactive wax; and (d) crosslinking composition of claim 2. 21. A composition which may be used for coating, said composition comprising: (a) reactive organic resin which is polyhydroxy- functional, polyepoxy- functional, or both epc :v- functional and hydroxy- functional; (b) color- imparting pigment; (c) reactive wax; and (d) crosslinking composition of claim 3. 22. The composition of claim 21 wherein the reactive organic resin comprises polyhydroxy- functional reactive organic resin. 23. The composition of claim 22 wherein the polyhydroxy- functional reactive organic resin comprises polyhydroxy- functional polyester resin. 24. The composition of claim 23 wherein the polyhydroxy- functional polyester resin contains, on average, at least two hydroxyl groups per molecule. 25. The composition of claim 23 wherein the polyhydroxy-functional polyester resin has a hydroxyl number of at least 5. 26. The composition of claim 23 wherein the polyhydroxy- functional polyester resin is a polyhydroxy- functional substantially saturated polyester resin. 27. The composition of claim 21 wherein the reactive organic resin comprises polyepoxy- functional reactive organic resin. 28. The composition of claim 27 wherein the polyepoxy- functional reactive organic resin contains, on average, at least two epoxy groups per molecule. 29. The composition of claim 27 wherein the polyepoxy- functional reactive organic resin comprises polyglycidyl ether of polyhydric alcohol. 30. The composition of claim 29 wherein the polyhydric alcohol comprises bisphenol A. 31. The composition of claim 27 wherein the polyepoxy- functional reactive organic resin contains at least one epoxycycloaliphatic group. 32. The composition of claim 21 wherein the color- imparting pigment comprises a member selected from the group consisting of titanium dioxide, color- imparting organic pigment, and a mixture of two or more thereof. 33. The composition of claim 21 wherein the reactive wax comprises a member selected from the group consisting of normal primary alkanol having from 12 to 20 carbon atoms, normal saturated monocarboxylic acid having from 8 to 20 carbon atoms, normal saturated monocarboxylic amide having from 8 to 20 carbon atoms, and a mixture of two or more thereof . 34. The composition of claim 21 wherein the reactive wax comprises stearyl alcohol. 35. The composition of claim 21 wherein: (a) the reactive organic resin constitutes from 20 to 80 percent by weight of the coating composition; (b) the color- imparting pigment constitutes from 1 to 45 percent by weight of the coating composition; (c) the reactive wax constitutes from 0.1 to 20 percent by weight of the coating composition; and (d) the crosslinking composition constitutes from 1 to 20 percent by weight of the coating composition. 36. An article comprising a ceramic substrate having thereon at least one coating of the composition of claim 21 which has been crosslinked. 37. The article of claim 36 wherein the ceramic substrate is glass. 38. The article of claim 36 wherein the ceramic substrate is a glass bottle.

Inventors: MONTAGUE ROBERT A, MORRIS GEORGE D, NEHMSMANN LOUIS J, TANG ROBERT H, WANG ALAN E, ZHANG YINGCHAO, MONTAGUE, ROBERT, A., MORRIS, GEORGE, D., NEHMSMANN, LOUIS, J., TANG, ROBERT, H., WANG, ALAN, E., ZHANG, YINGCHAO
Applicants: PPG IND OHIO INC, PPG INDUSTRIES OHIO, INC.
Application year: 2000
Main classification: C09D175
IPC codes: B41M1, C03C17, C08G18, C09D175