GB1562971A - Organic metal finishes - Google Patents

Description

(54) ORGANIC METAL FINISHES (71) We, AMERICAN CYANAMID COMPANY, a corporation organised and existing under the laws of the State of Maine, United States of America, of Berdan Avenue, Township of Wayne, State of New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to coating compositions useful as organic metal finishes.

Organic metal finishes have been commercially available for a great number of years. Coatings from natural materials such as linseed oil were superseded in time by synthetic polymeric materials. Frequently these earlier materials were dissolved in organic solvents and deposited by any of a number of conventional methods to.

metallic substrates and dried or baked to produce the desired coating on the metal substrates. Some of these earlier coating compositions were not as hard nor as chemically resistant to solvents and acids as desired and as a consequence, further developments produced blends of crosslinkable polymeric materials which were used in conjunction with a crosslinking agent which, when the combination was used as a coating on a metallic substrate and then baked so as to convert the crosslinkable polymeric material and the crosslinking agent to a thermoset state, provided a hard, chemical resistant film. Presently, the most commonly used crosslinking agents are based on triazines such as melamine, benzoguanamine or the ureas, including urea per se and thiourea.However, these crosslinking agents do not fill all of the needs of the present time and newly developing coating applications. These newly developing coating applications require in certain instances superior full performance than that which is achievable at the present time with the already known crosslinking agents. In more recent times, because of ecology considerations, it is desirable to furnish aqueous systems which provide an aqueous dispersion of the blended materials although such provision is not intended to replace entirely the solvent systems.

The present invention is in the coating resin field and provides an organic solvent solution or an aqueous dispersion of a mixture or blend of certain partially or fully alkylated glycoluril derivatives and certain organic solvent soluble or water dispersible non-gelled, non-self-crosslinking polymeric materials that are acid catalyzed and which can be deposited on a substrate by any one of a number of methods, including coating, spraying, dipping, brushing, roller coating and electrocoating, and after the application of the coating composition to the metal substrate, the coated substrate can be baked at the appropriate temperature wherein the crosslinking agent through the assistance of the acid catalyst, crosslinks with the polymeric material and produces a hard, chemical resistant film.

In accordance with the present invention there is provided an organic solvent solution or an aqueous dispersion of a mixture of from 2% to 50%, by weight, of (A) a glycoluril derivative having the structural formula:

wherein n is an integer from I to 4 inclusive; mis O, 1 or 2;R is hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive; and R2 and R3 are separately hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive or a phenyl radical; and correspondingly from 98% to 50%, by weight, of (B) an organic solvent soluble or a water dispersible non-gelled, normally non-self-crosslinking (under normal baking conditions) polymeric material, which polymeric material contains as reactive groups, any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups wherein the amount of said groups is at least 0.5%, by weight, and not more than 25%, by weight, based on the total weight of said polymeric material; and (C) from 0.05% to 5.0%, by weight, of an acid catalyst based on the total weight of (A) and (B); wherein said reactive groups of (B) are heat reactive with (A) and wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B). Normal baking conditions for these coatings are generally 200"C. or less for 30 minutes or less.

In the last ten years, dramatic changes have taken place in the organic coating technology. There have been increased emphasis on pollution free coating systems such as aqueous emulsion, water-borne coatings, electrocoating, powder coatings and ultra-violet light curable coatings. The existing cross-linking agents based on melamine, the guanamines, including benzoguanamine, or urea and substituted ureas do not fill all the needs of the present coating market. The glycoluril derivatives used in the present invention are a new class of cross-linking agents, the starting material of which is glycoluril (also known as acetylene diurea) which is prepared by reacting two moles of urea with one mole of glyoxal. The glycoluril can be methylolated, partially or fully, by reacting one mole of glycoluril with between one and four moles of formaldehyde.When the glycoluril is fully methylolated, it is identified as tetramethylol glycoluril. The methylolated glycolurils can be alkylated, either partially or fully, depending on whether or not the glycoluril is partially or fully methylolated and depending further on whether or not partial or full alkylation is desired. In one embodiment, for example, the glycoluril derivative is at least dimethyolated and at least monoalkylated. If the tetramethylol glycoluril is reacted with a selected amount of a monohydric aliphatic or cycloaliphatic alcohol containing from one to six carbon atoms, one can produce, for instance, the tetra(alkoxy methyl)glycoluril or partially alkylated glycolurils. These monohydric alcohols may be primary or secondary alcohols.The monohydric alcohols that can be used to achieve this alkylation may be, for example, methanol, ethanol, n-propanol, n-butanol, n-amyl alcohol, n-hexyl alcohol, isobutanol, isopropanol, sec-butanol and cyclohexanol.

Some of these glycoluril derivatives are already identified in the chemical literature but in order to illustrate the method for the preparation thereof, the following preparations are set forth in which all parts are parts by weight unless otherwise indicated.

Preparation of Glycoluril Into a suitable reaction vessel equipped with stirrer, thermometer, and reflux condenser, there was introduced 765 parts of urea and 875 parts of water. To this slurry, 282 parts of concentrated sulfuric acid were charged and the mixture was heated to 700 C. At 70"C., 605 parts of glyoxal (40% aqueous solution and free from formaldehyde) were added slowly to the clear solution such that the reaction temperature is maintained between 75--80"C. After the addition of glyoxal, the reaction mixture was held at 750C. for one hour and then cooled. The separated crystalline glycoluril was filtered and washed with water and a dilute caustic aqueous solution. The glycoluril obtained after drying has a m.p. of 2980-3000C.

and the yield was 88% (525 parts).

Preparation of Tetramethylol Glycoluril Into a suitable reaction vessel equipped with a stirrer, thermometer, and reflux condenser, there was introduced 688 parts (10 moles) of aqueous formaldehyde (44%), and the pH was adjusted to 8.7 with 22 parts of 0.5N NaOH solution. To this solution, 284 parts~tZ moles of glycoluril were added ai 400 C.

During the reaction, the temperature was allowed to rise up to 550C. At this stage, most of the glycoluril went into solution. After about 15 minutes, the pH was adjusted to 8.0 with five parts of 0.5N NaOH. A clear pale yellow colored solution was obtained. The clear solution was distilled at 50 C. under reduced pressure to remove water, until the reaction vessel content was about 640 parts. The syrup in the vessel was poured into 800 parts of methanol. The white crystalline precipitate was filtered and dried. The total yield of the tetramethylol glycoluril was 483 parts (92% yield) and m.p. 1320--1360C.

Preparation of Tetrabutoxymethyl Glycoluril Into a suitable reaction vessel equipped with a stirrer, thermometer, and reflux condenser there was introduced 1,000 parts (13.5 moles) of n-butanol and 7.0 parts of concentrated nitric acid and 20 parts of water. To this mixture was added 200 parts of tetramethylol glycoluril (0.76 mole) and the reaction mixture was stirred at 40"C. for two hours. The reaction mixture became a clear solution. It is then distilled at reduced pressure between 450-500C. to remove the butanol/water azeotrope mixture.After 260 parts of the n-butanol/water mixture were removed, 260 parts of n-butanol were added to the clear solution and the reaction temperature was lowered to 220-250C. The solution was neutralized with 10% caustic to a pH 9-10, followed by removal of more of a n-butanol/water mixture under reduced pressure. The residue was filtered with a filter aid. The resulting water-white syrup had a Gardner-Holdt viscosity of Y-Z (25 OC.). Pan solids were 95% (2 hours at 105"C.) and foil solids were 97% (45 minutes at 450C.). The gel phase chromatography indicated that the product was 85% monomeric. The nuclear magnetic resonance (nmr) of the product confirmed the structure of the monomer to be tetrabutoxymethyl glycoluril.

Preparation of Tetrabutoxymethyl Glycoluril Into a suitable reaction vessel equipped with a stirrer, thermometer, and reflux condenser there was introduced 344 parts (5 moles) of aqueous formaldehyde (44%) and the pH was adjusted to 7.5 with 6 parts of 0.5N NaOH solution. To this solution, 142 parts of glycoluril (1 mole) were added and the reaction mixture was heated to 800 C. Two parts of 0.5N NaOH solution were added to adjust the pH to 7.0. In half an hour, the reaction mixture became a clear solution. It was then cooled to 250C. and the pH was adjusted to 7.4 with three parts of 0.5N NaOH solution. The clear pale yellow colored solution was then distilled at 550 C. under reduced pressure to remove water.After 150 parts of water were removed, 740 parts (10 moles) of n-butanol and 1 part of concentrated nitric acid were added to the resulting syrup. The mixture was heated to reflux with stirring. After about 10 minutes, the reaction mixture became clear and water white; the reflux temperature was 95-980C. The water formed during the reaction was decanted by the use of a standard decant apparatus. In about three hours, 150 parts of decant liquid (water with 8% n-butano) were collected. The reaction temperature after that period was 115"--116"C. When water stopped coming over by decant, the solution was cooled to 220--240C. and neutralized with 10 parts of 0.5N NaOH solution.The excess butanol was removed at atmospheric pressure, and later under reduced pressure, and residual syrup was filtered in the presence of activated charcoal and filter aid. The yield of the resulting syrup was 410 parts (approximately 87% yield). The other physical characteristics were as follows: Foil Solids: 96.4%; Pan Solids: 94.7%; Gardner-Holdt Viscosity (25"C.): P-Q; Gardner Color: 1; Water Tolerance: 321.

Preparation of Partially Methylated Glycoluril Into a suitable reaction vessel equipped with a stirrer, thermometer, and reflux condenser there was introduced 950 parts (30 moles) of methanol and 40 parts of concentrated hydrochloric acid. To this mixture, 262 parts (1 mole of tetramethylol glycoluril) were added and the reaction mixture was stirred at 25--300C. In about 15-20 minutes, all the tetramethylol glycoluril went into solution. After half an hour, the reaction mixture was neutralized with 140 parts of sodium bicarbonate and 20 parts of sodium carbonate at 220--230C. The pH after neutralization was about 8. The salt was filtered. The filtrate was concentrated at 600 C. under reduced pressure.The yield of the syrupy product after filtration of the salt was 290 parts, which was diluted to 90% solids with "Cellosolve" (registered Trade Mark). The product characteristics were as follows: Foil Solids: 91.4%; Pan Solids: 82.2%; and Gardner-Holdt Viscosity (250C.): Z,. IR of the product indicated that the methylated product has a significant amount of unreacted methylol groups.

Preparation of Tetramethoxymethyl Glycoluril Into a suitable reaction vessel equipped with stirrer, thermometer, and condenser were charged 640 parts (20 moles) of methanol and 20 parts of 70 iO con.

nitric acid. To this acidic methanol, 262 parts (1 mole) of tetramethylol glycoluril were charged, and the reaction mixture was heated to 400C. with stirring. In about 20 minutes, all of the tetramethylol glycoluril went into solution. When the reaction mixture became clear, it was cooled to 220 C. and 45 parts of 20% sodium hydroxide solution were added to neutralize the reaction mixture to a pH of 7-8. The neutralized clear solution was heated to 500--550C. and 450 parts of methanol were removed under slightly reduced pressure. The residue in the flask crystallized on standing for a few hours. l he crystalline solids were filtered and washed with a small amount of water. The filtrate was then vacuum stripped at 700--800C to remove all the water.The solid residue was then dissolved in benzene and the undissolved salt was removed by filtration. The benzene solution was mixed with the first crop of solid crystals and dissolved with additional benzene and was filtered again. On removal of benzene, 310 parts of tetramethoxymethyl glycoluril (TMMGU) was obtained. The yield was 97%. It was recrystallized from benzene.

The recrystallized product had the melting point of 116"--118"C. The structure of TMMGU was confirmed by I.R., N.M.R. and nitrogen analysis.

Preparation of Dimethoxymethyl Diethoxymethyl Glycoluril Into a suitable reaction vessel equipped with stirrer, thermometer, and condenser, were charged 320 parts (10 moles) of methanol), 460 parts of ethanol (10 moles), and 20 parts of 70% concentration of nitric acid. To this acidic alcoholic mixture, 262 parts (1 mole) of tetramethylol glycoluril were charged, and the reaction mixture was heated to 400C. with stirring. In about 20 minutes, all of the tetramethylol glycoluril went into solution. When the reaction mixture became clear, it was cooled to 220 C. and 45 parts of 20% sodium hydroxide solution were added to neutralize the reaction mixture to pH 7-8. The neutralized clear solution was heated slowly to 1050C. under reduced pressure, to remove substantially all of the alcohol-water mixture.The resulting syrup was filtered hot at 800 C. to remove the inorganic salt and other impurities. The yield of the syrupy dimethoxymethyl diethoxymethyl glycoluril was 320 gms. The structure of this product was confirmed by N.M.R. The Pan Solids were 95.0%, and Foil Solids were 98.5%. The Gardner-Holdt viscosity was Z3-Z4 (25"C.).

The glycoluril materials used in the composition of the present invention are identified as glycoluril derivatives notwithstanding the fact that many of the materials used in this category will be modified glycoluril compounds. On the other hand, some measure of self-condensation may take place in the preparation of these glycoluril derivatives which will result in the production of polymeric materials such as dimers, trimers, tetramers and the like which would put them in the category of condensation products or resinous materials. However, only lower molecular weight compounds, resinous materials or condensation products are preferred for use in this application, namely those that have a molecular weight less than 5000 and more preferably between about 200 and about 2,000.

These glycoluril derivatives may contain from one to four methylol groups or they may contain from one to four alkoxymethyl groups or any combination of from one to four methylol groups and alkoxymethyl groups. When there is only one methylol group or only one alkoxymethyl group, there must be at least one methylene bridge.

Among the glycoluril derivatives that may be used as the crosslinking agent in the compositions of the present invention, are the dimethylol glycoluril, trimethylol glycoluril, tetramethyl glycoluril, monomethylether of dimethylol glycoluril, the dimethylether of dimethylol glycoluril, the trimethylether of tetramethylol glycoluril, the tetramethylether of tetramethylol glycoluril, tetrakisethoxymethyl glycoluril, tetrakispropoxymethyl glycoluril, tetrakisbutoxymethyl glycoluril, tetrakisamyloxymethyl glycoluril, tetrakishexoxymethyl glycoluril and the like. If desired, one may utilize mixed ethers such as the diether, dimethylethers of tetramethylol glycoluril, the diethyl, dipropylethers of tetramethylol glycoluril, the dibutyl, diethylethers of tetramethylol glycoluril, the diethyl, dihexylethers of tetramethylol glycoluril and the like.When water solubility is desired, it is preferred to make use of the lower alkoxy derivatives such as the tetrakismethoxymethyl glycoluril. On the other hand, when the use of colloidal dispersions of laticiferous dispersions are to be used, the higher alkoxy derivatives can be used such - as the tetrakisbutoxymethyl glycoluril. If desired, these crosslinking agents may be used singly or in combination with one another although it is generally preferred to use these crosslinking agents singly. The amount of the glycoluril derivatives used in the compositions of the present invention may be varied from 2% to 50%, by weight, based on the total solids weight of the glycoluril derivatives and the water-dispersible, non-gelled, non-selfcrosslinking polymeric material.It is preferred to use the glycoluril derivatives (in the same weight percent basis) in amounts varying from 10% to 40%, by weight.

There obviously will then be present in the composition from 50% to 98%,- by weight, of the non-self-crosslinking polymeric material and preferably from 60% to 90%, by weight, of said polymeric material, same basis, wherein the percentages of the glycoluril derivative and the polymeric material, by weight, total 100% and are based on the total solids weight of the glycoluril derivative and the polymeric material.

The component (B) used in the composition of the present invention is an organic solvent suitable or water-dispersible non-gelled, non-self-crosslinking polymeric material which contains certain reactive groups including any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups. The amount of said groups that is present in said polymeric material may be varied from 0.5V by weight, to not more than 25%, by weight, based on the total weight of said polymeric material. For most technical purposes these reactive groups will be the sole reactive groups in the polymeric material. Any one of these reactive groups may be present in the polymeric material to the exclusion of the other reactive groups or all three of these three reactive groups may be present in the polymeric material simultaneously.These polymeric materials may be anionic or non-ionic.

These polymeric materials may be any one of a plurality of vinyl polymers which may be prepared by polymerizing polymerizable monomers containing reactive carboxyl groups, such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, p-benzoyl acrylic acid and polycarboxylic acids of the a,-ethylenically unsaturated class such as maleic, fumaric, itaconic, mesaconic, aconitic and the halogenated acids such as the halogenated maleic, or more specifically, chloromaleic acid.These carboxylic groups containing monomers can be used either singly or in combination with one another in the required amount and may be used with other polymerizable monomers that contain reactive alcoholic hydroxy groups or reactive amide groups or may be used with other monomers which contain no reactive groups other than the reactive ethylenic double bond including no carboxylic groups such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, heptyl methacrylate, decyl methacrylate, propyl crotonate, butyl crotonate and nonyl crotonate. These polymerizable monomers devoid of any reactive groups may be used singly or in combination with one another in copolymerizing with a monomer containing a reactive group of the class described.Still further, one could use such other polymerizable compounds containing no reactive groups such a styrene, o-, m-, or p-alkyl styrenes such as the o-, m-, or p-methyl, ethyl, propyl and butyl styrenes, 2,4-dimethyl styrene, 2,3-dimethyl styrene, 2,5-dimethyl styrene, vinyl naphthalene, methyl vinyl ether, n-butyl vinyl ether, phenyl vinyl ether, acrylonitrile, methacrylonitrile, halo ring or side chain styrenes such as chloro styrene, o-, m-, or p-chlorostyrene, 2,4-dichlorostyrene, 2,3-dichlorostyrene, 2,5-dichlorostyrene or the alkyl side chain styrenes such as the a-methylstyrene and a-ethylstyrene.

If one wishes to prepare a polymeric material as component (B), utilizing a polymerizable monomer containing a reactive alcoholic group, one may use such polymerizable vinyl monomers as the hydroxy alkyl esters of the a,,l, unsaturated monocarboxylic acids such as the hydroxy alkyl esters of acrylic acid, methacrylic acid, ethacrylic and the chloro as well as the other chloro substituted acrylic acids.

These esters may either have a primary or a secondary hydroxyl group. Illustrative of the types of compounds that can be used to make the polymers containing the reactive alcoholic hydroxy groups are 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 8-hydroxyoctyl acrylate, 2 hydroxyethyl methacrylate, 5-hydroxyhexyl methacrylate, 6-hydroxyoctyl meth acrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 3-hydroxy propyl crotonate, 4-hydroxyamyl crotonate, 5-hydroxyamyl crotonate, 6-hydroxy hexyl crotonate, 7-hydroxyheptyl crotonate, and 10-hydroxydecyl crotonate.

These hydroxy esters may be used either singly or in combination with one another or with the polymerizable vinyl monomers devoid of any reactive group including those set forth hereinabove in the discussion of the carboxyl group-containing monomers. Obviously, these hydroxy ester monomers may be used in combination with the reactive carboxyl group-containing monomers set forth hereinabove.

Among the amide group-containing monomers which may be used to prepare the polymeric material identified as component (B) are acrylamide, methacrylamide and ethacrylamide. These polymerizable acrylamides may be used to prepare the polymeric materials used in the present invention with any of the carboxyl group-containing monomers and/or the hydroxyl group-containing monomers or with any of the polymerizable monomers set forth hereinabove that are devoid of any reactive groups. These polymeric materials whether they contain the reactive carboxyl groups and/or the reactive alcoholic hydroxy groups and/or the reactive amide groups will be anionic polymeric materials.

Additionally, one can make use of polyester resin compositions which are organic solvent dispersible, non-gelled, polymeric materials. Organic solvent dispersible alkyd resins, whether oil free or glyceride oil-containing, may be used and a plurality of these materials are commercially available and are also well known in the art and, as a consequence, it is not deemed necessary to make any prolonged recitation of such materials since they are fundamentally prepared by reacting a polyhydric alcohol with a polycarboxylic acid or with anhydrides such as phthalic anhydride, maleic anhydride, and the like.

Additionally, one can make use of polyester resin compositions which are water-dispersible, non-gelled, anionic polymeric materials. Water-soluble alkyd resins or water-dispersible alkyd resins, whether oil free or glyceride oil-containing, may be used and a plurality of these materials are commercially available and are also well known in the art and, as a consequence, it is not deemed necessary to make any prolonged recitation of such materials since they are fundamentally prepared by reacting a polyhydric alcohol with a polycarboxylic acid or with anhydrides such as phthalic anhydride, maleic anhydride, and the like.

Additionally, one can use certain polyether polyols such as those prepared by reacting one mole of bis-phenol A and/or hydrogenated bis-phenol A with at least two moles of ethylene oxide and/or propylene oxide.

The following examples are illustrative of the various kinds of organic solvent soluble, non-gelled, non-self-crosslinking polymeric materials which can be used in the composition of the present invention.

Polyester Resin A This oil free saturated polyester resin is commercially available and is prepared by reacting isophthalic acid, adipic acid and propylene glycol in a conventional esterification process. This polyester resin is identified as a saturated polyester resin inasmuch as it is free of non-benzenoid unsaturation. The polyester, designed for coil coating, has the following characteristics: Solids 70% in "Solvesso" (registered Trade Mark) 150, a thigh boiling hydrocarbon solvent; Gardner-Holdt viscosity (25"C.) z1-z3; acid number 10 maximum; hydroxy number 30.

Resin B Resin B is a polyether polyol, that is available commercially. Resin B is prepared by reacting one mole of bis-phenol A with four moles of ethylene oxide.

This polyether polyol has a hydroxyl number of about 260270.

Acrylic Resin C Acrylic resin C is a commercially available anionic acrylic polymer prepared by the standard polymerization techniques in an iert organic solvent such as 2 ethoxyethanol in which 55 parts of n-butylacrylate, 30 parts of styrene, and 15 parts of acrylic acid are copolymerized. At the end of the polymerization, the resulting polymer is diluted to 75% solids with n-butanol. The average molecular weight of the polymeric material is about 10,00020,000 and has an acid number of 115. This polymer is designed for water-based coatings and electrocoatings. At 75% solids and 250C., it has a Gardner-Holdt viscosity of Z6+.

Resin D Into a suitable reaction vessel equipped with a stirrer, thermometer, inert gasinlet and outlet tubes and partial condenser, there was introduced 668 parts of neopentyl glycol, 96 parts of trimethylol propane, 509 parts of isophthalic acid and 448 parts of adipic acid. These reactants were heated under a blanket of nitrogen gas to a temperature of 2300 C., while the water of esterification was continuously removed with constant agitation. After 7 hours, the acid number of the reaction mass was 9. The reaction mass was cooled to 150 C. and diluted to 90% solids with a 1:1 mixture of n-butyl acetate and cellosolve acetate. The final product had the Gardner-Holdt viscosity of Z+ at 90% solids. The resin had a hydroxyl number of 88 and an acid number of 9.

The following examples are illustrative of the various kinds of waterdispersible, non-gelled, non-self-crosslinking polymeric materials which can be used in the compositions of the present invention.

Polyester Resin E Into a suitable reaction vessel equipped with an agitator, thermometer, inert gas-inlet tube and partial condenser, there was introduced 866 parts of neopentyl glycol, 56 parts of trimethylol propane, 74 parts of dimethylol propionic acid, 303 parts of adipic acid and 240 parts of a mixture of oligomers containing about 70% of trimer acid and about 13% of dimer acid and 17% of monomer acid, by weight, wherein said oligomers are derived from tall oil fatty acids which are primarily oleic and linoleic acids, 74 parts of dipropylene glycol and 1087 parts of isophthalic acid.

These reactants were heated under a blanket of nitrogen at a temEerature of about 165 to 1900C. while the water of esterification was continuously removed with constant agitation. The heating was then increased and the temperature slowly rose to about 230"C. as the isophthalic acid reacted. When the reaction mass was clear, the acid number was about 2025, the temperature was quickly lowered to about 190"C. and 64 grams of trimellitic anhydride were added. After holding the reaction mass for an additional 30 minutes at 1850C., the acid number was 44. The resin was cut to a 75% resin solids content using a mixture of n-butanol and 2butoxy ethanol.The cut resin solution had a viscosity of Z,, Z, on the Gardner Holdt scale at 250 C.

Acrylic Emulsion F Acrylic emulsion F is a commercially available acrylic emulsion polymer prepared by polymerizing a monomer blend of 55 parts of n-butylacrylate, 30 parts of styrene, and 15 parts of acrylic acid. The emulsion has an acid number of 90100 on a solids basis and a final solids content of about 48%.

Acrylic Emulsion G Acrylic Emulsion G was prepared by a standard aqueous emulsion polymerization technique using the monomer blend of 45 parts of n-butyl acrylate, 32 parts of methyl methacrylate, 21 parts of acrylonitrile, and 2 parts of methacrylic acid. For the emulsion polymerization, 0.42 part of ammonium persulfate and 2 parts of an alkyl sulfosuccinate were used as an initiator and as a surfactant, respectively. The emulsion polymerization was carried out at 800 C. The final product had a solids content of 50% and had an acid number of 13.

Acrylic Emulsion H Acrylic emulsion H was prepared by a procedure very similar to that used in preparing the acrylic emulsion G. in this polymerization, the monomer composition was a blend of 45 parts of n-butyl acrylate, 28 parts of methyl methacrylate, 19 parts of acrylonitrile, 3 parts of methacrylic acid and 5 parts of 2hydroxyethyl acrylate. The final product had a solids content of 43% and an acid number of 19, as well as a hydroxyl number of 24.

Polyether Polyol I Polyether polyol I was prepared by reacting one mole of bisphenol A (4,4' isopropylidene diphenol) with 6 moles of ethylene oxide. The resulting product had a viscosity of 2840 centipoises and a hydroxyl number of 215. The molecular weight of the polyether polyol I was about 520. Polyether polyol I was a liquid material.

The third essential component (component C) used in the compositions of the present invention is an acid catalyst. This catalyst is used in an amount varying from 0.05% to 5.0%, by weight, based on the total solids weight of (A) and (B). It is preferred to use from 0.1% to 2.5%, by weight, of the said catalyst, same basis.

Among the preferred acid catalysts that may be used in the compositions of the present invention are: trismethyl sulfonylmethane, trishexyl sulfonylmethane, ptoluene sulfonic acid, n-dodecyl benzene sulfonic acid, naphthalene sulfonic acid, and dinonyl naphthalene disulfonic acid. The catalytic acitivity of an acid can also be generated in the coating compositions of the present invention by incorporating sulfonic acid groups into the polymeric material (B). This can be achieved, for example, by copolymerizing from 0.1% to 5.0% (based on the total monomer weight) of a monomer such as 2-sulfoethyl methacrylate, or stryene sufonic acid. It is also possible to use alkyl esters of phosphoric acid or alkylphosphonic acids as the acid catalyst in the coating compositions of the present invention.

Weaker organic acids, such as formic acid, acetic acid and phthalic acid may be used but are not preferred because they are not effective in promoting the crosslinking reaction at temperatures below 175 C. in a reasonable period of time such as less than 30 minutes.

Inorganic acids such as nitric, sulfuric, phosphoric, hydrohalic and Lewis acids may also be used.

In order that the concept of the present invention may be more completely understood, the following examples are set forth in which all parts are parts by weight unless otherwise indicated.

Examples 1 and 2 and Comparative Example 3 Three paint formulations, shown hereinbelow in Table I, were prepared utilizing the oil-free saturated polyester resin A and a crosslinking agent which, in the first and second examples, was the tetrabutoxymethyl glycoluril (TBMGU) and in the third comparative example, the crosslinking agent was hexakismethoxymethylmelamine (HMMM). In Examples 1 and 2, the resincrosslinking agent ratios were 76/24 and 83/17 respectively. In the comparative Example 3, the resin-crosslinking agent (HMMM) ratio was 90/10. ft had been determined from experience that the best film properties were obtained at this level of HMMM content and when the cure temperature of 2300 C. was used for 60 seconds. These organo-soluble enamels were prepared by using a three roll mill.

The enamels, thus prepared, were drawn down on Alodine 1 200S treated aluminum panels using a 0.002 drawblade. Some of the films were cured at 2300 C. for 60 seconds and others were cured at 2600C. for 60 seconds. In Table II, set forth hereinbelow, there is shown the film properties obtained from the three formulations. Table II shows that the enamels prepared from TMBGU are superior in performance over that prepared from HMMM in the following respects: (a) shows no impact frilling either on overbake or exposure to humidity; (b) superior humidity resistance; (c) better fabrication properties as shown by a good TV bend. The enamels based on the TBMGU show good oven bake gloss retention and superior accelerated weathering tests.

TABLE I Comparative Example Example Example 1 2 3 Titanium dioxide Pigment 119.3 119.3 119.3 Saturated Polyester Resin A 56.9 56.9 68 Saturated Polyester Resin A 105.4 84.0 119.5 TBMGU (97.5%) 37.1 23.0 "Cellosolve" acetate 18.9 18.9 18.9 HMMM - - 14.3 Silicone L 5310 resin 0.15 0.15 0.15 Isophorone 2.5 6.8 2.6 Diacetone alcohol 2.5 4.8 11.3 Butyl "Cellosolve" 3.0 3.0 3.0 'Solvesso"* 150 34.5 64.1 20.0 N-Butanol 16.9 17.1 13.0 p-Toluene sulfonic acid 0.3 0.3 0.3 Pigment/Binder 80/100 90/100 80/100 Resin/Crosslinker 76/24 83/17 90/10 *"Solvesso" is a registered Trade Mark TABLE II ENAMEL PROPERTIES Comparative Example Example Example 2 3 Polyester Resin A/CLA 76/24 83/17 90/10 Crosslinking agent (CLA) TBMGU TBMGU HMMM Cure cycle, 60", seconds 230 C 260 C 230 C 260 C 230 C Film thickness, mils 0.8 0.8 0.8 0.8 1.0 Gloss, 600 - 95 94 92 97 Gloss, 200 - 87 80 82 89 Knoop hardness (KH N25) 3.8 7.4 5.0 9.2 6.2 Impact, reverse, in Ibs. 70 70 70 70 70 Fabrication potential, T-bend passes TO TO TO T-2 T-0 toT-l TABLE II (Continued) NAMEL PROPERTIES Comparative Example Example Example 1 2 3 Adhesion, cross hatched and taped 100 100 100 100 100 MEK Resistance, double rubs 200+ 200+ 200+ 200+ 200+ Oven bake 60" Gloss, 20 % retention 100 98 100 100 100 Impact frilling, none on impact bump 60 60 70 50 70 T-bend, no popping on bend T-2 T-2 T-O T-2 T-1 to T-2 Cure cycle, 60" seconds 260 C 230 C 260 C Effect of Cleveland Humidity test (600 C) on the impacted enamel (10 to 70 in. Ibs.) - 70 70 70 Initial impact resistance, reverse, passes 70 70 70 After 1 hour - 70 70 40 After 24 hours - 70 70 40 After 4 days - 70 70 40 After 8 days - 70 70 40 After 18 days - 70 70 40 Badly blistered Blister free Blister free enamel surface surface surface Cure Cycle 60 seconds 230 C 260 C 230 C Accelerated Weathering Test (XENON ARC) Initial Gloss 60 95 95 95 Initial Gloss 20 82 87 86 After 1,000 Hours Gloss 600 89 89 79 Gloss 20 62 62 47 Example 4 A high solids organic solvent based enamel was prepared using polyether polyol B and acrylic resin C in combination with tetrabutoxymethyl glycoluril (TBMGU). 33 Parts of polyether polyol B, 34 parts of acrylic resin C and 33 parts of the tetrabutoxymethyl glycoluril were blended together in a suitable blending mill. To this blend is added 0.5 part of n-dodecylbenzene sulfonic acid, 1.0 part of dim ethyl aminoethanol and 90 parts of titanium dioxide pigment. The pigment was dispersed in the blend using a Cowles dissolver. The dispersed pigment paste was diluted to 75% solids with cellosolve. At 75% paint solids the Ford cup #4 viscosity was about 60 seconds. The enamel was sprayed on iron phosphate pretreated cold rolled steel panels and cured at 150 C. for 20 minutes.The cured films had the following properties: Film thickness 1.0 mil Pencil hardness H-2H Knoop hardness (KHN25) 12.0 Gloss 60 77 Initial impact Resistance, in. Ibs. (Reverse) 60 Impact popping after exposure to Cleveland Humidity Test (600 C. on the impacted enamel) After one hour, in. Ibs. 60 After two hours, in. Ibs. 50 After 24 hours, in. Ibs. 50 The enamel, after storage at 550C. for three weeks, was stable.

Example 5 Into a three roll mill there is introduced 332 parts of titanium dioxide pigment which was dispersed with 233 parts of the acrylic resin C. To this pigment paste, 133 parts of the acrylic resin C, 92 parts of the tetrabutoxymethyl glycoluril (TBMGU), 194 parts of xylene, 23 parts of "Cellosolve" acetate, 23 parts of n-butanol, and 8 parts of p-toluene sulfonic acid dissolved in 12 parts of isopropanol were charged and mixed thoroughly on a mechanical shaker. The resulting organo-soluble paint had a Ford cup #4 viscosity of 62 seconds at 250C. The paint solids were 68%.

Films were drawn down on zinc phosphate pretreated cold rolled steel, using a 0.002" drawblade, and these coated panels were cured at 1750C. for 20 minutes.

The film properties were as follows: Film thickness 1.0 mil Gloss 60 76 Gloss 20" 50 Pencil Hardness F-H Knoop Hardness 6.0 Reverse impact resistance, in. Ibs. 5050 MEK resistance (Double rubs) > 200 Humidity resistance (Cleveland Humidity No change in gloss Chamber,60 C.) after 10 days Salt spray resistance (ASTM #B 11744) 240 hrs.

Creepage along the scribe line less than 1/32" Blisters None Example 6 Into a three roll mill there is introduced 346 parts of titanium dioxide pigment and 210 parts of polyester resin D and 10 parts of cellosolve acetate and the three components were dispersed together to form a pigment paste. To this pigment paste there is charged 103 parts of the polyester resin D, 115 parts of tetrabutoxymethyl gycoluril (TMBGU), 3.1 parts of dinonyl naphthalene disulfonic acid, 117 parts of n-butanol and 88 parts of butylacetate. The charge was mixed thoroughly on a mechanical shaker. The resulting paint had a Ford cup #4 viscosity of 60 seconds at 25"C. The paint solids were 73%.Films were drawn down on zinc phosphate pretreated cold rolled steel panels, using a 0.002" drawblade and the panels were baked so as to cure the coatings at 175"C. for 20 minutes. The film properties were as follows: Film thickness 1.0 mil Gloss 60 86 Gloss 20 52 Pencil hardness 2H-3H Knoop hardness li-A Reverse Impace resistance, in. Ibs. 140+ MEK resistance (Double rubs) > 200 Humidity resistance (Cleveland Humidity No change in gloss chamber, 60"C.) after 10 days Salt spray resistance (ASTM #B 11764) 240 hrs.

Creepage along the scribe line less than 1/32" Blisters None Example 7 & Comparative Example 8 Paint formulations shown in Table III hereinbelow were prepared utilizing Acrylic resin C and a crosslinking agent which, in the first instance, was the tetrabutoxymethyl glycoluril (TBMGU) and in the second instance was hexakismethoxymethyl melamine (HMMM). In both formulations the resincrosslinking agent ratios were identical. The amounts and kinds of ingredients used in the formulations were as shown in Table III. These water-based enamels were prepared by using a three roll mill and a Cowles dissolver. The enamels thus prepared were drawn down on zinc phosphate pretreated cold rolled steel using 0.003 inch drawblade. The films were cured at 1750C. for 20 minutes. Table III shows the film properties obtained from the two formulations. The films based on the TBMGU have higher reverse impact of 3040 inch-pounds against 1020 inch-pounds for the films based on the HMMM. The humidity and salt spray resistance are far superior in the case of TBMGU, as shown in Table III. For instance, after 500 hours of the salt spray test (ASTM Specification No.

B-l 1764) on the film based on TBMGU had no blisters and no creepage at the scribe line.

TABLE III COMPARATIVE EXAMPLE 7 EXAMPLE 8 Titanium dioxide pigment 186.5 186.5 Acrylic Resin A (75% solids) 124.2 124.2 Dimethyl amino ethanol 9.7 9.7 Dispersed the mixture on a three roll mill and added: - Acrylic Resin C (75%) 124.3 124.3 TBMGU (97%) 48 HMMM 46.7 Dimethylamino ethanol 9.8 9.8 p-toluenesulfonic acid 0.45 0.45 Water, deionized 495 496.5 Pigment/Binder 80/100 80/100 Resin/Crosslinker 80/20 80/20 Paint Solids 42 42 Film Properties Cure Cycle, 20 min. at 1750C.

Film thickness, mil 0.8 0.8 Gloss, 600 90 89 Gloss, 20 69 71 Knoop hardness (KHN25) 7.6 10.7 Impact resistance, reverse, in Ibs. 300 1020 MEK Resistance, double rubs 200+ 200+ Salt spray resistance (ASTM #B 117-64) 240 hrs. * ** 500 hrs. * *no creepage along the scribeline-no blisters **23 mm creepage along the scribeline-no blisters TABLE III (Continued) COMPARATIVE EXAMPLE 7 EXAMPLE 8 Cleveland Humidity:Resistance (Cleveland Humidity Chamber, 60"C) Initial Gloss 20 78 80 % Gloss retention after 3 days 96*** % Gloss retention after 5 days 96*** 99*** % Gloss retention 87 few 87 few after 11 days scattered scattered blisters blisters % Gloss retention 74 few to after 18 days medium blisters ***no blisters ****blisters very dense Example 9 204 Parts of titanium dioxide pigment were dispersed in 164 parts of Polyester resin E, and 5 parts of Acrylic resin C, and 8 parts of dimethylamino ethanol, using a three roll mill. To this pigment grind, 109 parts of Polyester E, 50 parts of TBMGU, 0.5 part of p-toluene sulfonic acid, and 7 parts of dimethylamino ethanol were added and blended using a high speed disperser, followed by the addition of 441 parts of deionized water.The resultant water-borne enamel had Ford cup #4 viscosity of 60 seconds at about 46% solids.

The enamel thus prepared was drawn down on iron phosphate pretreated cold rolled steel using 0.003" drawblade. The films were cured at 175"C. for 20 minutes.

The film properties were as follows: The cured films had a thickness of 1.0 mil. They were hard and resistant to organic solvents such as acetone, methyl ethyl ketone, etc. the film properties were as follows: 600 gloss: 96; Knoop hardness: 6.2; reverse impact: 120 kn.-lbs. After 240 hours salt spray exposure, there were no blisters on the films and very little creepage on the scribe line. The humidity resistance (Cleveland humidity chamber, 60"C.) after 2 weeks was excellent. There were no blisters on the film or any loss of gloss. Overbake stability of the film was excellent.

Examples 10, 11 and 12 Paint formulations shown in Table IV were prepared utilizing Acrylic resin C and the crosslinking agent tetramethoxymethyl glycoluril (TMMGU). Three formulations were prepared at the resin/crosslinking agent (TMMGU) ratios of 75/25, 70/30, and 65/35 respectively on a solids basis. In all the formulations, the pigment-binder ratio was 80/100, and dimethyl aminoethanol was used to neutralize 60% of the available carboxylic groups of the acrylic resin. p-Toluene sulfonic acid was used as the catalyst. The water-based enamels were prepared by using a three roll mill by a procedure, similar to that described in Example 7. The final paint solids and the viscosity of these enamels are shown in Table IV. The enamels thus prepared were drawn down on zinc phosphate pretreated cold rolled steel using 0.003" drawblade.The films were cured at 1750C. for 20 minutes. Table IV shows the film properties and Table IV continued shows the results of salt spray resistance with the variations in the level of crosslinking agent content (TMMGU). Table IV shows excellent film properties. The best corrosion resistance of the film was obtained at the resin crosslinker ratios of 75/25 and 70/30 respectively.

TABLE IV Comparative salt spray resistance of tetramethoxymethyl glycoluril Effect of resin/cross-linking agent ratio on salt spray resistance of the films Examples 10 11 12 Acrylic resin C 75 70 65 Tetramethoxymethyl glycoluril 25 30 35 pTSA 0.2 0.2 0.2 Pigment/Binder ratio 80/100 80/100 80/100 Pigment: Titanium dioxide Enamel Properties Viscosity, FC-4, secs. 75 77 70 % Total non-volatile 46 48 50 Film Properties(1 Cure Cycle, 20 min. at 1750C.

Film thickness, dry, mils 0.8 0.8 0.8 Color, Photovolt, blue 90 92 88 Gloss, 600 92 92 89 Initial Film Properties: Gloss, 200 86 83 82 Hardness, Pencil H-2H H-2H H-2H Hardness, Knoop KHN25 8.9 10.0 10.8 Impact resistance, reverse, inch Ibs., max. 10 10 MEK resistance, double rubs 200+ 200+ 200+ Film thickness, dry, mils 1.0 1.0 1.0 Color, Photovolt, blue, % 92 92 94 Film Properties after aging Enamels 7 Days at 55"C:: Gloss, 60 93 94 94 Gloss, 200 88 89 84 Hardness, Pencil F-H -F-H F-H Hardness, Knoop KHN25 7.0 7.7 7.2 Impact resistance, reverse, inch Ibs., max. 10 10 10 MEK resistance, double rubs 200+ 200+ 200+ TABLE IV (Continued) Comparative salt spray resistance of tetramethoxymethyl glycoluril Effect of resin/cross-linking agent ratio on salt spray resistance of the films Examples 10 11 12 Acrylic resin C 75 70 65 Tetramethoxymethyl glycoluril 25 30 35 pTSA 0.2 0.2 0.2 Salt Spray Resistance "' Cure temperature, 20 minutes at 1750C.

Initial Gloss Readings 60 Gloss 95 96 94 20O Gloss 92 95 91 Appearance after 240 hour exposure Gloss 10 10 10 Creepage, max. inches 1/16 1/16 1/16 Peel test'3 9 9 3 Blisters 8VF 8VF 8VF 480 hour exposure Gloss 10 10 10 Creepage, max. 3/32 3/32 1/8 Peel test'2' 6 6 3 Blisters none'3' none'3' none(3' 1 Sprayed "Bonderite" 100 to approx. 1 mil dry film thickness (panels pre-heated 30 min. at l750C.)-"Bonderite" is a registered Trade Mark 2'10=excellent adhesion (no bare spots) 7-9=good adhesion; a few widely scattered bare spots; max. from scribe line, 1/16" 4--6=fair adhesion; less than 1/8" max. exposure bare metal O--3=poor adhesion; greater than 1/8" min. exposure bare metal 3' some rust spots Example 13.

Paint Formulation 245 Parts of the Acrylic emulsion F, 95 parts of deionized water, 103 parts of dimethoxymethyl diethoxymethyl glycoluril, 308 parts of titanium dioxide pigment, and 4.1 parts of dimethylamine ethanol were sand milled. After the pigment was properly dispersed, an additional 245 parts of the Acrylic emulsion F, were slowly added, followed by 0.72 part of p-toluene sulfonic acid dissolved in 1 part of isopropanol, 4.1 parts of dimethylamino ethanol, and 45 parts of deionized water.

The resultant water-based enamel had the Ford cup #4 viscosity of 50 seconds at 25"C. at a solids content of 61%. The films were drawn down on zinc phosphate pretreated cold rolled steel, using 0.002" drawblade, and they were cured at 1750C.

for 20 minutes. The film properties were as follows: Film thickness 1.0 mil Gloss 60 92 Gloss 20 79 Knoop hardness 14.4 Pencil hardness H-2H Reverse impact resistance, in. Ibs. 0-10 MEK resistance (Double rubs) > 200 The water-based enamel, after aging at 550C. for 21 days, had excellent stability. There was no pigment settlement and there was no change in the film properties of the coatings prepared from the aged enamel.

Example 14 A clear water-borne varnish was prepared by blending on a high speed stirrer 60 parts of the Acrylic emulsion G, 3.3 parts of tetramethoxymethyl glycoluril, 1.2 parts of dimethyl amino ethanol, 0.06 part of p-toluene sulfonic acid dissolved in the same amount of isopropanol, and 10 parts of deionized water. The resultant varnish was drawn down on aluminum panels (alodine 1200S treatment) and separately on iron phosphate treated cold rolled steel panels, using a No. 22 wire cator. The films were cured at 1500C. for 20 minutes, and at 2600C. for 60 seconds or 90 seconds.The film properties were as follows: Substrate: Alodine 1200S Cure conditions 1500C/20 min. 260"C./60 sec Film Thickness 0.65 mil 0.6 mil Knoop Hardness 6.9 7.4 Pencil Hardness H-2H H-2H MEK resistance (Double rub) > 200 > 200 Reverse impact resistance in Ibs. > 60 > 60 Substrate:Zinc phosphate treated cold rolled steel Cure conditions 150"CJ20 min. 260 C./90 sec Film Thickness 0.75 mil 0.8 mil Knoop Hardness 6-8 6-8 Pencil Hardness H-2H H-2H MEK resistance (Double rub) 90 > 200 Example 15 A clear water-borne varnish was prepared by blending 67 parts of the acrylic emulsion H, 10 parts of tetramethylol glycoluril dissolved in 5 parts of water and 0.21 part of 50% aqueous solution of p-toluene sulfonic acid. The initial viscosity of the varnish was 15 cps. and had a pH of 4.75. The varnish was drawn down on aluminum (alodine 1200S treatment), using a No. 34 wire cator. The films were cured at 125"C. for 20 minutes and 260"C. for 1 minute.The film properties were as follows: Cure Condition 125"C./20 min. 260"C./1 min.

Film Thickness 1.0 mil 1.0 mil Knoop Hardness 3.3 4.8 MEK Resistance (Double rubs) 200 200 A comparable varnish film of 1.0 mil, prepared without any tetramethylol glycoluril, and cured at 125"C. for 20 minutes had knoop hardness of 2.3, and MEK resistance of less than 9 rubs. The varnish containing tetramethylol glycoluril was aged for 3 weeks at 550 C. after which there was no coagulation or phase separation in the varnish. The brookfield viscosity was unchanged, and the pH was 3.45. The aged varnish cured as well as the initial formulation.

Example 16 60 Parts of Polyether polyol I, 40 parts of dimethoxymethyl diethoxymethyl glycoluril, and 90 parts of titanium dioxide were dispersed in a high speed Cowles dissolver. To this dispersed pigmented paste were added 1.2 parts of p-toluene sulfonic acid, dissolved in 1.8 parts of isopropanol and blended together on a high speed stirrer, followed by the addition of 17 parts of deionized water. The resultant water-based high solids enamel had the Ford cup #4 viscosity of 60 seconds at 25"C. The films were drawn down with a 0.003" draw down blade on zinc phosphate pretreated cold rolled steel panels and were cured at 1250C. for 20 minutes.The film properties were as follows: Film thickness 1.1 mil Gloss 60 94 Gloss 20 79 Knoop Hardness (25 g.) 11.7 Pencil Hardness H-2H Reverse Impact Resistance (in. lbs.)100--120 MEK resistance (double rubs) > 200 The water-based high solids enamel had good shelf stability. There were no significant changes in the film properties of the coating prepared from the enamel after aging for two weeks at 550C.

The compositions of the present invention can also find utility in the field of electrodepositions when used in the presence of an acid catalyst: The following example is illustrative of a paint formulation which is useful in electrocoating.

Example 17 Into a high speed disperser there was introduced 77 parts of Acrylic resin C (75% solids), 22 parts of TBMGU, 11.5 parts of diisopropanol amine, (50% solution) and 22 parts of titanium dioxide pigment. These materials were dispersed together in the high speed disperser and the dispersed pigment paste was diluted by slow addition of deionized water to the extent of 1,000 parts so as to make up a paint solids solution of 10%. To the 10% aqueous paint, there was added 0.5 part of dinonyl naphthalene disulfonic acid, preneutralized with diisopropanol amine. The 10% aqueous paint had a pH of 8.2 and conductivity of 780 j ohm-l cam~'. The paint was aged overnight with constant stirring at ambient temperature.Zinc phosphate pretreated cold rolled steel panels were electrocoated at 150 volts for 60 seconds.

The electrocoated steel panel was rinsed with deionized water and then cured at 175 C. for 20 minutes. The cured film was 0.8 mil thick. It was resistant to methylethyl ketone rubs and other organic solvents. The Knoop hardness was 7.4 (KHN25) and reverse impact resistance was 20-30 inch-pounds. The enamel, when exposed to salt spray resistance tests for 240 hours, had 2-3 mm. creep age at the scribe lines and no blisters on the surface.

In the compositions of the present invention the component (B) is identified as an organic solvent soluble or a water-dispersible, non-gelled, non-self-crosslinking polymeric material which polymeric material contains as reactive groups any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups wherein the amount of said groups is at least 0.5%, by weight, and not more than 25%, by weight, based on the total weight of said polymeric material. The British Patent 1,146,858 and its French counterpart, 1,486,213 (Florus et al.), disclose the use of certain glycoluril derivatives in combination with self-crosslinking polymeric materials.

The component (B) of said Florus et al. patents is a copolymer which may contain from 10 to 70 parts, by weight, of polymerized units of an ester of acrylic acid and/or methacrylic acid with a monohydric alcohol having from one to twenty carbon atoms and from 2 to 15 parts, by weight, of polymerized units of an a ethylenically unsaturated carboxylic acid containing from 3 to 6 carbon atoms and from 0 to 85 parts by weight of polymerized units of at least one other ethylenically unsaturated comonomer. These patents teach that their copolymers may contain N-methylolacrylamide and/or N-methylolmethacrylamide and also the ethers of these amides with monohydric alcohols having from one to ten, and preferably 3 to 4, carbon atoms in amounts between about 0.5 to 40 and particularly 5 to 20 parts by weight.When these copolymers contain either the methylol acrylamides or the alkyl ethers of these methylol acrylamides, the copolymers are self-crosslinking.

These polymeric materials of these patents will self-crosslink under normal cure conditions of about 150 to 1750C. in a period of from 20 to about 60 minutes. The tetrabutoxymethyl glycoluril in the coating compositions of the Florus et al. patents does not function as a crosslinking agent with the polymeric material at the cure temperature of 1500C. If anything, it only plasticizes the film and it does not function as an effective crosslinker but only as an additive to improve corrosion resistance.

The compositions of the present invention, on the other hand, contain a waterdispersible polymeric material which is not self-crosslinking but does contain -COOH, -OH and/or -CONH2 as the sole reactive groups and these groups do not self-condense at the practical cure conditions of 1500 to 1750C. in a period of 20 to 60 minutes. In order to achieve efficient crosslinking reaction of the glycoluril derivatives with a non-self-crosslinking polymeric material of the class used in the compositions of the present invention requires the presence of an acid catalyst. The French and British patents cited above do not disclose, teach or suggest the use of any acid catalyst in their compositions.

In order to illustrate the contrasting differences between the composition of the Florus et al. patents and the compositions of the present invention, two acrylic resins were prepared, namely Acrylic resin J and Acrylic resin K, which were substantially identical in composition except that the Acrylic resin J contained 125 parts of isobutoxymethylacrylamide whereas the Acrylic resin K was devoid of any isobutoxymethylacrylamide. Otherwise, the formulations were identical. The monomer composition in each of these Acrylic resin formulations is set forth hereinbelow.

Monomer Composition: Resin J (Parts) Resin K (Parts) 2-Ethyl hexyl acrylate 120 120 Acrylic acid 25 25 Isobutoxymethylacrylamide 125 2-h ydroxyethylacryl ate 30 30 Styrene 200 200 These acrylic resins J and K were prepared separately in reaction vessels equipped with a stirrer, reflux condenser and a nitrogen inlet tube. The Acrylic resin J had a monomer composition similar to those described in the French patent 1,486,213 with these minor inconsequential differences. Instead of the Nbutoxymethylacrylamide and the 4-hydroxybutylacrylate there was substituted isobutoxymethyl acrylamide and 2-hydroxyethylacrylate respectively. The Acrylic resin K had the identical monomer composition as that of the Acrylic resin J except there was present no isobutoxymethylacrylamide.The general procedure of the resin preparations is as follows: To the suitably equipped reaction vessel there is charged 200 parts of isbutanol and heated to 100-150 C. To the heated solvent, there is added the monomer blend containing about 2%, by weight, based on the total monomer weight, of t-butyl perbenzoate and 2%, by weight, based on the total monomer weight, of n-dodecylmercaptan. These additives are charged into the reaction vessel over a period of two hours while maintaining the temperature of the solvent at about 100-105 C, After the monomer addition has been completed, the reaction temperature is held at about 105 C. for one hour. One part of additional@tbutyl perbenzoate is added and the reaction is maintained at 105 C. for one more hour. Later the resin syrup in each instance is cooled and adjusted to 65% solids with isobutanol.

Four coating formulations were prepared from each of these acrylic resin polymeric materials by blending the resins J and K separately with or without TBMGU and p-toluene sulfonic acid in the amounts shown in Table V set forth hereinbelow. The films drawn down were about one mil thick and were drawn down on zinc phosphate pretreated cold rolled steel panels. A total of twenty-four panels were prepared. These panels were baked at 150 C. for 30 minutes, 150 C.

for 60 minutes and 175 C. for 20 minutes. The film properties on these panels are shown in Table VI.

TABLE V COATING COMPOSITIONS (WEIGHT BY PARTS) Components 1 2 3 4 5 6 7 8 Resin J 38.5 61.5 38.5 61.5 - - - Resin K - - - - 38.5 61.5 38.5 61.5 TBMGU - 10.0 - 10.0 - 10.0 - 10.0 pTSA Catalyst - - 0.08 0.2 - - 0.08 0.2 TABLE VI Coating Compositions 1 2 3 4 5 6 7 8 Bake Temperature 150 C./30 Minutes: Film Thickness, mils 1.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 MEK Rub Resistance Passes Passes Passes Passes Fails Fails Fails Passes Test (200 Rubs) (Film Soft) Pencil Test Hardness H-2H F-H H-2H H-2H HB-F 2B-B F-H 2H-3H Bake Temperature 150 C./60 Minutes:: Film Thickness, mils 1.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 MEK Rub Resistance Test (200 Rubs) Passes Passes Passes Passes Fails Fails Fails Passes Pencil Test Hardness 2H-3H F-H 2H-3H H-2H HB-F F-H F-H 2H-3H Bake Temperature 175 C./20 Minutes Film Thickness, mils 1.1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 MEK Rub Resistance Test (200 Rubs) Passes Passes Passes Passes Fails Passes Fails Passes Pencil Test Hardness H-2H F-H H-2H H-2H HB-F H-2H HB-F H-2H In water-dispersed coating compositions, if the polymeric material contains carboxylic acid groups, it is essential to use ammonia or a water-soluble organic amine in the composition in order to achieve the water-dispersibility of the total composition. The amount of ammonia or of the organic amine required is dictated by the amount of carboxylic acid groups present in the polymer.Normally, equivalent amounts of amine with respect to the carboxylic groups are sufficient to achieve water-dispersibility of the polymer and the coating composition. It is also possible to use only 10% to 20% of the equivalent amounts of amine with respect to the carboxylic acid groups of polymer, to achieve a water-dispersible composition.

One can use ammonia or the water-soluble low molecular weight organic amines such as the primary, secondary or tertiary amines such as, for example, ethylamine, diethylamine, triethylamine, diethanolamine, N-N-dimethylethanolamine, and diisopropanolamine.

Although not required, in certain cases it may be helpful to make use of anionic or non-ionic surfactants to obtain stable water dispersions of these organic coating compositions. The anionic surfactants, for example, can be sulfosuccinate, sodium dioctylsuccinate or sodium cyclohexylsuccinate. A number of these anionic surfactants are available commercially. The non-ionic surfactants can be ethoxylated alkyl phenol and the like. The amount of the surfactant that is normally used is less than 4%, by weight, based on the total paint solids weight.

Although the coatings of the present invention will principally be used to coat metals such as steel, aluminum and the like, these coatings can also be used on other substrates such as wood, glass, plastics, paper and textiles.

WHAT WE CLAIM IS: 1. A coating composition which is an organic solvent solution comprising a blend of from 2% to 50%, by weight, of (A) a partially or fully alkylated glycoluril derivative having the following the following structural formula:

wherein n is an integer from 1 to 4 inclusive; m is 0, 1 or 2; each R is, individually, hydrogen or an alkyl radical containing from 1 to 6 carbon atoms, inclusive, wherein the said alkyl radicals may be the same or different alkyl radicals; and R2 and R3 are separately hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive or a phenyl radical; and correspondingly from 98% to 50%, by weight, of (B) an organic solvent soluble, normally non-self-crosslinking polymeric material having as reactive groups, any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups wherein the amount of said groups is at least 0.5% by weight, and not more than 25%, by weight, based on the total weight of said polymeric material; and (C) from 0.05% to 5.0%, by weight, of an acid catalyst based on the total weight of (A) and (B), wherein said reactive groups of (B) are heat reactive with (A) and wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B).

2. A coating composition according to Claim 1, wherein the glycoluril derivative is fully alkylated.

3. A coating composition according to Claim 2, wherein the fully alkylated glycoluril derivative is fully butylated.

4. A coating composition according to Claim 2, wherein the fully alkylated glycoluril derivative is fully methylated.

5. A coating composition according to Claim 1, wherein the glycoluril derivative is a mixed fully alkylated ether of tetramethylol glycoluril.

6. A coating composition according to Claim 5, wherein the glycoluril derivative is the diethyl ether, dimethyl ether of tetramethylol glycoluril.

7. A coating composition according to Claim 1, in which the glycoluril derivative is only partially alkylated.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (28)

**WARNING** start of CLMS field may overlap end of DESC **. In water-dispersed coating compositions, if the polymeric material contains carboxylic acid groups, it is essential to use ammonia or a water-soluble organic amine in the composition in order to achieve the water-dispersibility of the total composition. The amount of ammonia or of the organic amine required is dictated by the amount of carboxylic acid groups present in the polymer. Normally, equivalent amounts of amine with respect to the carboxylic groups are sufficient to achieve water-dispersibility of the polymer and the coating composition. It is also possible to use only 10% to 20% of the equivalent amounts of amine with respect to the carboxylic acid groups of polymer, to achieve a water-dispersible composition. One can use ammonia or the water-soluble low molecular weight organic amines such as the primary, secondary or tertiary amines such as, for example, ethylamine, diethylamine, triethylamine, diethanolamine, N-N-dimethylethanolamine, and diisopropanolamine. Although not required, in certain cases it may be helpful to make use of anionic or non-ionic surfactants to obtain stable water dispersions of these organic coating compositions. The anionic surfactants, for example, can be sulfosuccinate, sodium dioctylsuccinate or sodium cyclohexylsuccinate. A number of these anionic surfactants are available commercially. The non-ionic surfactants can be ethoxylated alkyl phenol and the like. The amount of the surfactant that is normally used is less than 4%, by weight, based on the total paint solids weight. Although the coatings of the present invention will principally be used to coat metals such as steel, aluminum and the like, these coatings can also be used on other substrates such as wood, glass, plastics, paper and textiles. WHAT WE CLAIM IS:

1. A coating composition which is an organic solvent solution comprising a blend of from 2% to 50%, by weight, of (A) a partially or fully alkylated glycoluril derivative having the following the following structural formula:

wherein n is an integer from 1 to 4 inclusive; m is 0, 1 or 2; each R is, individually, hydrogen or an alkyl radical containing from 1 to 6 carbon atoms, inclusive, wherein the said alkyl radicals may be the same or different alkyl radicals; and R2 and R3 are separately hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive or a phenyl radical; and correspondingly from 98% to 50%, by weight, of (B) an organic solvent soluble, normally non-self-crosslinking polymeric material having as reactive groups, any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups wherein the amount of said groups is at least 0.5% by weight, and not more than 25%, by weight, based on the total weight of said polymeric material; and (C) from 0.05% to 5.0%, by weight, of an acid catalyst based on the total weight of (A) and (B), wherein said reactive groups of (B) are heat reactive with (A) and wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B).

2. A coating composition according to Claim 1, wherein the glycoluril derivative is fully alkylated.

3. A coating composition according to Claim 2, wherein the fully alkylated glycoluril derivative is fully butylated.

4. A coating composition according to Claim 2, wherein the fully alkylated glycoluril derivative is fully methylated.

5. A coating composition according to Claim 1, wherein the glycoluril derivative is a mixed fully alkylated ether of tetramethylol glycoluril.

6. A coating composition according to Claim 5, wherein the glycoluril derivative is the diethyl ether, dimethyl ether of tetramethylol glycoluril.

7. A coating composition according to Claim 1, in which the glycoluril derivative is only partially alkylated.

8. A coating composition according to Claim 7, in which the glycoluril

derivative is only partially butylated.

9. A coating composition according to Claim 7, in which the glycoluril derivative is only partially methylated.

10. A coating composition according to Claim 1, in which the glycoluril derivative is a polymeric material having a molecular weight up to 5,000.

11. A coating composition according to any preceding claim, wherein the composition contains from 10% to 40%, by weight, of component (A), and correspondingly, from 90% to 60%, by weight, of component (B), wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B).

12. A modification of the coating composition defined in any preceding claim, wherein the acid catalyst component (C) is omitted and wherein component (B) contains sulfonic acid groups active to catalyse the reaction of component (A) with component (B).

13. A coating composition according to Claim 1 and substantially as described in any one of Examples 1, 2 and 16 herein.

14. A substrate coated with a coating composition according to any preceding claim which has been cured.

15. A coating composition which is an aqueous dispersion comprising a mixture of from 2% to 50% by weight of (A) a glycoluril derivative having the following structural unit:

wherein n is an integer from 1 to 4 inclusive; m is 0, 1 or 2; each R is individually either hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive; and R2 and R3 are separately hydrogen or an alkyl radical having from 1 to 6 carbon atoms inclusive or a phenyl radical; and correspondingly from 98% to 50% by weight, of (B) a water dispersible, normally non-self-crosslinking polymeric material having as reactive groups, any one or more of carboxyl groups, alcoholic hydroxyl groups or amide groups wherein the amount of said groups is at least 0.5% by weight, and not more than 25%, by weight, based on the total weight of said polymeric material; and (C) from 0.05% to 5.0%, by weight, of an acid catalyst based on the total weight of (A) and (B); wherein said reactive groups of (B) are heat reactive with (A) and wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B).

16. A composition according to Claim 15, in which the glycoluril derivative (A) is at least dimethylolated and at least monoalkylated.

17. A coating composition according to Claim 15, in which the glycoluril derivative (A) is fully methylolated.

18. A coating composition according to Claim 15, in which the glycoluril derivative (A) is fully alkylated.

19. A coating composition according to Claim 18, in which the glycoluril derivative (A) is fully butylated.

20. A coating composition according to Claim 18, in which the glycoluril derivative (A) is fully methylated.

21. A coating composition according to Claim 17, in which the glycoluril derivative (A) is only partially butylated.

22. A coating composition according to Claim 17, in which the glycoluril derivative (A) is only partially methylated.

23. A coating composition according to any one of Claims 15-22, in which the acid catalyst (C) is para toluene sulfonic acid.

24. A coating composition according to any one of Claims 15-22, in which the acid catalyst (C) is n-dodecylbenzene sulfonic acid.

25. A coating composition according to any one of Claims 15-24, wherein the composition contains from 10% to 40%, by weight, of component (A) and correspondingly, from 90% to 60% by weight of component (B), wherein said percentages of (A) and (B), by weight, total 100% and are based on the total solids weight of (A) and (B).

26. A modification of the coating composition defined in any one of Claims 15-25, wherein the acid catalyst component (C) is omitted and wherein component (B) contains sulfonic acid groups active to catalyse the reaction of component (A) with component (B).

27. A coating composition according to Claim 15 and substantially as described in any one of Examples 7 and 9-16 herein.

28. A substrate coated with a coating composition according to any one of Claims 1527 which has been cured.