GB2044780A - A water reducible alkyd resin coating composition - Google Patents

Abstract

A water reducible coating composition that by the addition of a solution of water and an amine or ammonia forms a sprayable nonair- polluting coating composition that can be dried at ambient temperatures and is useful for coating metal or plastic substrates and in particular for finishing or repairing automobiles and trucks comprises a water soluble organic solvent, pigments and a binder comprising (1) an alkyd resin that is the esterification product of soya fatty acids, isophthalic acid and trimethylol propane, having an acid number of 20-100 and an average molecular weight of 800-15,000, (2) an alkylated melamine formaldehyde resin, (3) an acrylic dispersing resin, and (4) an organo metallic drier. o

Description

SPECIFICATION A water reducible alkyd resin coating composition BACKGROUND OF THE INVENTION This invention is directed.to a coating composition and in particular to a coating composition that can be diluted with water to form a nonair polluting composition.

In view of stricter air pollution legislations and increased energy costs, it has become important for paint manufacturers to provide coating compositions that are nonair polluting and that dry under ambient temperature conditions. Along with the above, automotive and truck manufacturers and the automotive and truck repair industry require coating compositions that form finishes that are weatherable, durable, and have an excellent appearance. In particular, the repair industry requires finishes that have excellent adhesion to all types of painted or primed substrates. The novel coating composition of this invention meets the aforementioned requirements.

SUMMARY OF THE INVENTION A coating composition containing about 40-90% by weight of a film forming binder, about 10-60% by weight of a water soluble organic solvent and pigments in a pigment to binder weight ratio of about 1:100-75:100, wherein the binder is of about (1) 50-90% by weight, based on the weight of the binder, of an alkyd resin which is the esterification product of soya oil fatty acids, isophthalic acid and trimethylol propane and has an acid number of about 20-100 and a weight average molecular weight of about 800-15,000 determined by gel permeation chromotography; (2) 0.5-5% by weight, based on the weight of the binder, of an alkylated melamine formaldehyde resin; (3) 9-20% by weight, based on the weight of the binder, of an acrylic dispersing resin; (4) 0.5-5% by weight, based on the weight of the binder, of an organo metallic drier.

The composition can be reduced to an aqueous based composition having an acceptable application viscosity with an aqueous composition containing sufficient base to provide a pH of about 6.5-9.0.

DETAILED DESCRIPTION OF THE INVENTION The coating composition contains about 40-90% by weight of a film forming binder and usually about 70-85% by weight of the film forming binder. The remainder of the composition comprises a water soluble solvent. Minor amounts of water dispersible solvents can be added.

For application, the composition is reduced to an application viscosity of about 1 6 to 50 seconds measured according to ASTM-1084-63 with an aqueous reducer solution. This reducer solution contains up to about 20% by weight of a water soluble solvent or solvents and sufficient ammonia or amine or a combination thereof to form a salt of the alkyd resin and the acrylic dispersing resin and provide a pH of about 6.5-9. Usually a pH of about 7-8 is used.

Typical water soluble solvents that can be used to form the composition and the aqueous reducer solution are as follows: ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol propyl ether, isopropanol, ethanol, methanol, butanol and other alcohols, acetone, and the like. Small amounts of nonwater soluble solvents such as toluene, xylene, acetates and mineral spirits can be used. The amount of solvent added to the composition with the aqueous reducer solution can be adjusted to meet and comply with governmental regulations.

Ammonia or amine or a combination thereof used in the aqueous solution reacts with free carboxyl groups of the alkyd resin and acrylic dispersing resin to form salt groups which allow the resins to be dispersed in an aqueous medium. The pH of the resulting composition can be adjusted to the aforementioned values. Typical amines that can be used are triethylamine, trimethylamine, ethanolamine, N,N-diethylethanolamine, N,N-dimethylethanolamine, N-methylethanolamine, monoisopropanolamine, butanolamine, ethylenediamine, diethylamine and the like.

The composition can be a clear but usually contains a pigments in a pigment to binder weight ratio of about 1:100 to 75:100. Typical pigments that can be used are as follows: titanium dioxide, aluminum flake, red, yellow or orange iron oxide, "Irgazin" yellow and green, copper phthalocyanine green and blue, "Monastral" red, extender pigments and a wide variety of other organic an inorganic pigments.

The alkyd resin used in the composition is the esterification product of drying oil fatty acids, an aromatic dicarboxylic acid and a polyhydric alcohol. To prepare the alkyd resin, the above constituents along with an esterification catalyst are charged into a reaction vessel. Either a conventional fusion or solution process using conventional equipment can be used to prepare the alkyd resin. Generally reaction temperatures of about 200"-275"C. for 1 to 5 hours are used to prepare the resin. The resulting alkyd resin has an acid number of about 20-100 and a weight average molecular weight of about 800-15,000 and a number average molecular weight of about 800-400Q determined by gel permeation chromatography.

Typical solvents that can be used in the solution process for making the alkyd resin are water miscible or water soluble and are as follows: ethers, aliphatic alcohols such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol monoalkyl ethers, such as ethylene glycol monobutyl ether, propylene glycol monopropyl ether, ethylene glycol monoalkyl ether acetates, and the like.

Typical esterification catalysts that are used in the process for preparing alkyd resins are as follow: barium oxide, barium hydroxide, barium naphthenate, calcium oxide, calcium hydroxide, calcium naphthenate, lead oxide, lithium hydroxide, lithium naphthenate, lithium ricinoleate, sodium hydroxide, sodium naphthenate, zinc oxide, and lead tallate.

Typical drying oil fatty acids that are used to prepare alkyd resins are as follows: dehydrated castor oil fatty acids, heat-bodied soya oil fatty acids, tung oil fatty acids, linseed oil fatty acids, oiticica oil fatty acids, safflower oil fatty acids, soya oil fatty acids, and the like. Soya oil fatty acids are preferred.

Typical aromatic dicarboxylic acids that can be used to prepare the alkyd resin are as follows: isophthalic acid, terephthalic acid, phthalic acid. Isophthalic acid is preferred.

Typical polyhydric alcohols that can be used to prepare alkyd resins are as follows: ethylene glycol, propylene glycol, 1,3-butylene glycol, pentanediol, neopentyl glycol, hexylene glycols, diethylene glycol, dipropylene glycol, triethylene glycol, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, methylglucoside, dipentaerythritol, and sorbitol. Trimethylol propane is preferred.

Monobasic organic acids also can be used to prepare alkyd resins and are as follows: abietic acid, benzoic acid, p-tert-butylbenzoic acid, caproic acid, caprylic acid, crotonic acid, 2-ethylhexoic acid, lauric acid, pelargonic acid, rosin acids, and the like.

Monofunctional alcohols also can be used to prepare alkyd resins and are as follows: butanol, pentanol, hexanol, isooctanol, ethoxyethanol, and butyl carbitol.

Drying oils also can be used to prepare the alkyd resin such as castor oil, heat bodied soya oil, soya oil, corn oil, dehydrated castor oil, linseed oil, oiticica oil, safflower oil and tung oil.

One particularly preferred alkyd rein that forms a high quality composition is the esterification product of soya oil fatty acids/isophthalic acid/trimethylol propane that has an acid number of about 20-100 and preferably 35-45 and a weight average molecular weight of about 800-3500.

The alkylated melamine formaldehyde resin used in the composition can contain 1-4 carbon atoms in the alkyl group and is water soluble or water dispersible. One preferred resin that forms a high quality product is a partially methylated melamine formaldehyde resin that has an equivalent weight of about 225-325. By equivalent weight is meant, the grams of alkylated melamine formaldehyde resin required to react with one gram mole of carboxyl, hydroxyl or amide groups of a polymer.

The acrylic dispersing resin used in the composition contains sufficient carboxyl groups to disperse resin and pigments.

Useful types of resin are disclosed in Jakubauskas U.S. Patent 3,980,602 issued September 14, 1 976. One preferred resin that forms a high quality product is a polymer of methyl methacrylate/styrene/butyl acrylate/ acrylic acid. The following ratio of constituent is particularly preferred 25/30/35/10.

The composition contains organo metallic driers. Typical driers are cobalt naphthenate, managanese naphthenate, nickel naphthenate, nickel octoate, zirconium octate, lead tallate and the like.

One preferred combination of driers comprises zirconium octoate, cobalt naphthenate and 1,10 phenanthroline.

One particular useful coating composition of this invention comprises about 15-30% by weight of water soluble solvents and 70-85% by weight of a film forming binder. The binder is of about 80-85% by weight of the alkyd resin of soya oil fatty acids, isophthalic acid and trimethylol propane having an acid number of 35-45 and a weight average molecular weight, determined as above, of 800-3500;1-4% by weight of a partially methylated melamine formaldehyde resin having an equivalent weight of about 225-325, 13-17% by weight of an acrylic dispersing resin of styrene/methyl methacrylate/butyl acrylate/acrylic acid; and 1-3% by weight of an organo metallic drier of zirconium octoate, cobalt naphthenate and phenanthroline.

As aforementioned, the composition is pigmented for most uses. The pigments are formed into a mill base by grinding the pigment with the alkyd resin or acrylic dispersing resin and the resulting mill base is added to form a pigmented composition. The mill base is prepared by conventional grinding techniques such as sand grinding, ball milling, attritor grinding and the like. After reduction to an application viscosity with an aqueous solution containing ammonia or amine as discussed above, the composition can be applied to a variety of substrates by any of the conventional application methods such as spraying, electrostatic spraying, dipping, brushing, flow coating, roller coating and the like. The resulting coatings can be dried at ambient temperatures or baked at relatively low temperatures up to about 140"C. for about 5 minutes to 2 hours.The resulting coating is about 0.1-5 mils thick and is glossy, durable, weatherable, and has an excellent appearance.

The composition has excellent adhesion to all types of substrates such as wood, glass, bare metal, metal painted with the following: acrylic enamel, acrylic lacquer, acrylic dispersion enamel, acrylic dispersion lacquer, alkyd enamel, conventional alkyd or epoxy primers; fiberglass reinforced with polyester painted as above; acrylonitrile/butadiene/styrene plastics or other plastics painted as above. The aforementioned characteristics make the composition particularly useful as a finish or a refinish used for automobiles and truck bodies.

The following example illustrates the invention. All quantities are on a weight basis unless otherwise indicated.

Example 1 The following pigment dispersions are prepared: Parts White Pigment Dispersion By Weight Alkyd resin solution (80% by 16.57 weight solids alkyd resin of soya oil fatty acids/isophthalic acid/trimethylol propane having an acid No. of about 40 and a weight average molecular weight of about 900 determined by gel permeation chromatography) Ethylene glycol monoethyl ether 17.77 Titanium dioxide pigment 65.66 Total 100.00 The above constituents are blended together and charged into a conventional sand mill and ground to a 0.5 mil fineness.

Parts Black Pigment dispersion By Weight Portion 1 Alkyd resin solution des- 45.46 cribed above) Ethylene glycol monoethyl ether 18.91 Carbon Black Pigment 5.45 Portion 2 Alkyd resin solution (des- 22.73 cribed above) Ethylene glycol monoethyl ether 7.45 Total 100.00 Portion 1 is charged into an attritor and ground to a 0.25 mil fineness. Portion 2 is charged with the portion 1 into the attritor and ground to a 0.25 mil fineness.

Parts Blue Pigment Dispersion By Weight Acrylic Resin Solution (76% 26.19 solids in isopropanol of an acrylic polymer of 25% methyl methacrylate, 30% styrene, 35% butyl acrylate and 10% acrylic acid) Ethylene glycol monoethyl ether 29.32 Ethylene glycol monobutyl ether 11.41 Blue Pigment (phthalocyanine 23.Q8 blue pigment) Total 100.or The above constituents are charged into an attritor and ground to a 0.25 mil fineness.

The following tintings are prepared: Parts White Tinting By Weight White pigment dispersion 41.82 (prepared above) Alkyd resin solution (des- 41.62 cribed above) Methylated melamine formaldehyde 1.78 resin solution (80% weight solids of a partially methylated melamine formal dehyde resin having an equivalent weight of 225-325 in a 1:1 isopropanol/ isobutanol solvent) Acrylic resin solution (des- 9.23 cribed above) Toluene 0.58 Ethylene glycol monobutyl ether 4.73 Methyl ethyl ketoxime 0.24 Total 100.00 The above constituents are thoroughly mixed together ta form a tinting that has a pigment to binder weight ratio of about 57.97/100 and a volume solid content of 63.8%.

Parts Black Tinting By Weight Black pigment dispersion 39.07 (prepared above) Alkyd resin solution (des- 41.97 cribed above) Methylated Melamine Formalde- 2.35 hyde Resin Solution (described above) Methyl ethyl ketoxime 0.31 Ethylene glycol monobutyl ether 3.30 Acrylic resin solution (des- 13.00 cribed above) Total 100.00 The above constituents are thoroughly mixed together to form a tinting base that has a pigment to binder weight ratio of 3.2/100 and a volume solids content of about 63.84% Parts Blue Tinting By Weight Blue Pigment Dispersion (pre- 23.68 pared above) Alkyd resin solution (described 64.51 above) Methylated Melamine Formaldehyde 2.46 Resin Solution (described above) Methyl ethyl ketoxime 0.33 Acrylic resin solution (des- 6.58 cribed above) Ethylene glycol monobutyl ether 2.44 Total 100.00 The above constituents are thoroughly mixed together to form a tinting base that has a pigment to binder weight ratio of about 5/100 and a volume solids of about 63.71.

A drier composition is prepared by blending together the following: Zirconium Octoate solution containing 37.79 6% by weight zirconium in mineral spirits Cobalt Hydrocure solution (55% solids 56.60 cobalt naththenate in mineral spirits) 1,10 phenanthroline 5.61 Total 100.00 A thinner composition is prepared by blending together the following: Parts By Weight Ammonia solution (29% aqueous solution) 2.15 Deionized water 97.85 Total 100.00 A paint is formulated by blending together the following: Parts By Weight White tinting (prepared above) 99.68 Black tinting (prepared above). 0.27 Blue tinting (prepared above) 0.05 Drier composition (prepared above) 2.50 Total 102.50 A sprayable coating composition is prepared by blending 1 part by volume of the above paint with 1.5 parts by volume of the thinner.The resulting paint is sprayed onto the following panels: unprimed cold rolled steel, unprimed phosphatized steel, alkyd resin primed phosphatized steel, thermosetting acrylic enamel/alkyd resin primed steel, acrylic lacquer/alkyd resin primed steel. The panels are dried at an ambient temperature for about two hours and a dust free film is formed that is about 1-3 mils thick. After twenty-four hours the films have a hardness of about 1.1 knoops, a gloss measured at 20 of 86 and at 60' of 95 and water spot resistance of about 7 based on a scale of 0-10 where 10 represents no water spotting. After 1 week at ambient temperatures, the films have excellent resistance to gasoline, good chip resistance and cold crack resistance and improved resistance to water spotting.

Example 2 A silver mill base is prepared as follows: Parts By Weight Alkyd resin solution (des- 67.57 cribed in Example 1) Aluminum Paste (16.19 parts 24.91 of aluminum flake in 24.91- parts mineral spirits) Ethylene glycol monoethyl ether 7.52 Total 100.00 The above constituents are thoroughly blended together to form a mill base A thinner solution is prepared by blending together the following constituents: Parts By Weight Acetone 17.11 Diethylene glycol monobutyl ether 3.38 Deionized Water 77.34 Ammonia solution (29% aqueous solution) 2.17 Total 100.00 A silver paint is prepared by blending together the following constituents:: Parts By Weight Silver Mill Base (prepared 22.00 above) Acrylic resin solution (des- 12.42 cribed in Example 1) Methyl ethyl ketoxime 0.32 Ethylene glycol monoethyl ether 1.86 Alkyd resin solution (described 50.47 in Example 1) Methylated Melamine Formalde- 2.39 hyde Resin Solution (described in Example 1) Ethylene glycol monobutyl ether 6.07 Toluene 1.09 Drier Composition (prepared in 3.38 Example 1) Total 100.00 A sprayable composition is prepared by blending about 1 part by volume of the above paint with about 1.5 parts by volume of the above thinner solution. The resulting paint is sprayed onto phosphate treated steel panels coated with an alkyd resin primer and dried at ambient temperatures for two hours to form a 1-3 mil thick film.

After about two weeks at ambient temperatures the resulting films have a hardness of about 1.9 knoops, a gloss measured at 20 of 79 and a gloss measured at 60 of about 98. The films have excellent adhesion to the substrates and have an excellent appearance and good weatherability.

Example 3 A red mill base is prepared as follows: Parts By Weight Alkyd resin solution (described 23.45 in Example 1) Red Iron Oxide Pigment 56.29 Ethylene glycol monoethyl ether 20.26 Total 100.00 The above constituents are charged into a sandmill and are ground in a sandmill to a 0-2.5 mil fineness to form a mill base.

A thinner solution is prepared by blending together the following constituents: Parts By Weight Methanol 3.44 Diethylene glycol monobutyl ether 1.72 Isopropanol 13.96 Ammonia solution (29% aqueous 2.21 solution) Deionized Water 78.67 Total 100.00 A red paint is prepared by blending together the following constituents:: Parts By Weight Red Mill Base (prepared above) 16.38 Acrylic resin solution (des- 11.61 cribed in Example 1) Methyl ethyl ketoxime 0.30 Ethylene glycol monoethyl ether 1.68 Alkyd resin solution (des- 57.21 cribed in Example 1) Methylated Melamine Formalde- 2.24 hyde Resin Solution (described in Example 1) Toluene 1.67 Ethylene glycol monobutyl ether 5.75 Drier Composition (prepared in Example 1) 5.1 6 Total 100.00 A sprayable composition is prepared by blending about 1 part by volume of the above paint with about 1.5 parts by volume of the above thinner solution. The resulting paint is sprayed onto phosphate treated steel panels primed with an alkyd resin primer and baked for 30 minutes at 1 50'C. The resulting film is about 1-3 mils thick. The panels are exposed to ambient temperatures for about 1 week. The resulting films have a hardness of about 1.7 knoops and a gloss measured at 20 of about 85. The films have an excellent appearance and exhibit good weatherability.

Claims (11)

1. A coating composition comprising about 40-90% by weight of a film forming binder and about 10-60% by weight of a water soluble organic solvent and pigments in a pigment to binder weight ratio of about 1:100 to 75:100; wherein the binder consists essentially of about (1) 50-90% by weight, based on the weight of the binder, of an alkyd resin consisting essentially of the esterification product of soya oil fatty acids, isophthalic acid and trimethylol propane having an acid number of about 20-100 and a weight average molecular weight of about 800-15,000 determined by gel permeation chromatography; (2) 0.5-5% by weight, based on the weight of the binder, of an alkylated melamine formaldehyde resin;; (3) 9-20h/o by weight, based on the weight of the binder, of an acrylic dispersing resin and (4) 0.5-5% by weight, based on the weight of the binder, of an organo metallic drier.

2. The coating composition of claim 1 containing a sufficient amout of an aqueous reducer to provide an application viscosity of 1 6 to 50 seconds measured according to ASTM 1084-63; wherein the reducer comprises up to about 20% by weight of a water soluble solvent, water and sufficient base or amine or ammonia to provide the resulting composition with a pH of about 6.5-9.0.

3. The coating composition of claim 2 in which the base is ammonia.

4. The coating compostion of any one of claims 1 to 3 in which the alkyd resin has an acid number of about 35-45 and a weight average molecular weight of about 800-3500.

5. The coating composition of any one of claims 1 to 4 in which the alkylated melamine formaldehyde resin is a partially methylated melamine formaldehyde resin.

6. The coating composition of any one of claims 1 to 5 in which the acrylic dispersing resin consists of styrene/methyl metahcrylate/butyl acrylate/acrylic acid.

7. The coating composition of any one of claims 1 to 6 in which the organo metallic drier consists essentially of zirconium octoate, cobalt naphthenate and phenanthroline.

8. The coating composition of any one of claims 1 to 7 which comprises about 15-30% by weight of water soluble solvents and 70-85% by weight of a film forming binder.

9. The coating composition of any one of claims 1 to 7 which comprises about 15-30% by weight of water soluble solvents and 70-85% by weight of a film forming binder; wherein the binder consists essentially of (1) 80-85% by weight, base on the weight of the binder, of an alkyd resin having an acid number of about 35-45 and a weight average molecular weight of about 800-3500, (2) 1-4% by weight, based on the weight of the binder, of a partially methylated melamine formaldehyde resin having an equivalent weight of about 225-325, (3) 13-17% by weight, based on the weight of the binder, of an acrylic dispersing resin consisting of styrene/methyl methacrylate/butyl acrylate/acrylic acid, (4) 1-3% by weight, based on the weight of the binder, of an organo metallic drier consisting essentially of zirconium octoate, cobalt naphthenate and phenanthroline.

10. A coating composition substantially as hereinbefore described in any one of the Examples.

11. A metal substrate coated with about 0.1-5 mil thick layer of the dried coalesced composition of any one of Claims 1 to 10.

1 2. A coated metal substrate substantially as hereinbefore described in any one of the Examples.