GB2077276A - High Solids Acrylic Dispersion Lacquer - Google Patents

Abstract

A high solids acrylic dispersion lacquer coating composition useful as an exterior finish for automobiles and trucks comprises an acrylic polymer binder content of 25-45% by weight in a non-aqueous medium; wherein the acrylic polymer is a blend of (1) Polymer A of methyl methacrylate and a polymerized monomer of allyl methacrylate, alkyl amino alkyl methacrylate or mixtures thereof; (2) Copolymer B of methyl methacrylate and an alkyl acrylate having 6-12 carbon atoms in the alkyl group; and (3) A graft copolymer of Polymer A which forms a backbone of the graft copolymer and Copolymer B attached to the backbone which forms side chains of the graft copolymer; and wherein the non-aqueous medium is a blend of (a) an aliphatic solvent which at 25 DEG C is a non-solvent for Polymer A and a solvent for Copolymer B; and (b) a coalescing solvent for the binder. a

Description

SPECIFICATION High Solids Acrylic Dispersion Lacquer Background of the Invention This invention is related to a coating composition and in particular to a higher solids acrylic dispersion lacquer coating composition in a nonaqueous medium.

Acrylic dispersion lacquer coating compositions are well-known and are shown in Fryd and Lee U.S. Patent 3,660,537 issued May 2, 1972 and Lee and Victorius Canadian Patent 957,792 granted November 12, 1974. Compositions, such as described in the above patents, have been widely used in the automotive industry as a high quality exterior coating for automobiles and trucks and provide finishes of a high quality. However, these compositions do not comply with air pollution regulations that are being promulgated by many states and at the present state of the art cannot be brought into compliance with these regulations even with expensive pollution abatement equipment and techniques.

There is a need for a coating composition that will meet the following requirements: comply with current and future air pollution regulations with the use of pollution abatement equipment and techniques, form finishes on automobiles and trucks that have a good appearance, particularly good glamour, that are durable and weatherable and that can be spot repaired using conventional refinish procedures. The novel coating composition of this invention meets the above requirements.

Summary of the Invention A high solids acrylic polymer dispersion lacquer coating composition having an acrylic polymer binder content of about 2545% by weight in a nonaqueous medium; wherein the acrylic polymer binder is a blend of (1) Polymer A of polymerized methyl methacrylate and a monomer from the group of allyl methacrylate, alkyl amino alkyl methacrylate or mixtures thereof and having a weight average molecular weight, measured by gel permeation chromatography, of about 90,000-130,000; (2) Copolymer B of polymerized methyl methacrylate and an alkyl acrylate having 6-1 2 carbon atoms in the alkyl group and having a weight average molecular weight, measured as above, of 20,000-40,000;; and (3) A graft copolymer of Polymer A which forms a backbone of the graft copolymer and Copolymer B attached to the backbone which forms side chains of the graft copolymer and having a weight average molecular weight of about 60,000-110,000; wherein the nonaqueous medium is a blend of (a) an aliphatic solvent which at 250C is a nonsolvent for Polymer A and a solvent for Copolymer B; and (b) a coalescing solvent which at 500C is a solvent for the binder and at 250C is a nonsolvent for the binder.

Description of the preferred embodiments The acrylic dispersion lacquer coating composition has an acrylic polymer binder content of about 2545% by weight and is in a nonaqueous medium. The acrylic polymer binder is a blend of a Polymer A, a Copolymer B and a graft copolymer having a backbone and side chains attached thereto of Polymer A which forms the backbone and Copolymer B forms the side chains.

In the dispersion lacquer, Copolymer B is in solution. Polymer A is not in solution but is kept dispersed by the graft copolymer. The dispersion has a relatively high polymer solids content and a viscosity that allows spray application. Upon application of the dispersion to a substrate, a substantial amount of aliphatic nonsolvent evaporates and the dispersion is converted to a relatively high viscosity liquid on the substrate. This high viscosity liquid does not sag or flow on the substrate upon application. On baking of the coating, the remaining solvents coalesce the polymers into a smooth, glossy and continuous finish.

The acrylic polymer binder comprises about 2545% by weight of Polymer A, 5-25% by weight of Copolymer B and 4060% by weight of the graft copolymer. One particularly preferred acrylic binder comprises 35% by weight of Polymer A, 1 5% by weight of Copolymer B and 50% by weight of graft copolymer.

Polymer A is comprised of polymerized methyl methacrylate and allyl methacrylate, and optionally an alkyl amino alkyl methacrylate. Typically, Polymer A is comprised of 9099.5% by weight, based on the weight of Polymer A, of methyl methacrylate, 0.1-5% of allyl methacrylate and 0.45% by weight of alkyl amino alkyl methacrylate. Polymer A has a weight average molecular weight of about 90,000-130,000 and preferably 100,000-11 5,000.

The molecular weights of polymers referred to herein are determined by gel permeation chromatography using polymethyl methacrylate as a standard.

One preferred composition of Polymer A comprises 9799.5% by weight of methyl methacrylate, 0.4-1% by weight of diethylaminoethyl methacrylate and 0.12% by weight of allyl methacrylate having a weight average molecular weight of 100,000-11 5,000.

Typical alkyl amino alkyl methacrylates that are used to form Polymer A are: dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dipropylaminoethyl methacrylate, methylethylaminoethyl methacrylate, butylaminoethyl methacrylate, tertiary butylaminoethyl methacrylate, diethylaminopropylmethacrylate, diethylaminobutyl methacrylate, diethylaminopentyl methacrylate, diethylaminohexyl methacrylate and the like. Diethylaminoethyl methacrylate is preferred to form a quality coating composition.

Copolymer B is comprised of polymerized methyl methacrylate and an alkyl acrylate having 6- 12 carbon atoms in the alkyl group. Typically, Copolymer B is comprised of about 4060% by weight of methyl methacrylate and 4060% by weight of the alkyl acrylate. Copolymer B has a weight average molecular weight of about 20,000-40,000. One preferred composition of Copolymer B comprises 4060% by weight of methyl methacrylate and 4060% by weight of 2-ethylhexyl acrylate.

Typical alkyl acrylates that are used to form Copolymer B are: hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate and the like. 2-ethylhexyl acrylate is preferred to form a high quality product.

The graft copolymer has a backbone of Polymer A and side chains of Copolymer B attached thereto. Generally, the graft copolymer contains about 5080% by weight of Polymer A and 2050% by weight of Copolymer B and has a weight average molecular weight of about 60,000- 110,000.

The nonaqueous medium used in the composition is a blend of (1) an organic aliphatic solvent which at 250C is a nonsolvent for Polymer A and remains a nonsolvent at elevated temperatures for Polymer A and is a solvent for Copolymer B at 250C and (2) a coalescing solvent which at 500C and above is a solvent for the binder and form a high quality finish. At 250C the coalescing solvent preferably is not a solvent for the binder as only a small percentage of the binder may solubilized or swollen by the coalescing solvent. Generally, the nonaqueous medium of the composition contains about 3565% by weight, based on the weight of the nonaqueous medium, of the aliphatic solvent and 3565% by weight of coalescing solvent.

If the aliphatic solvent and the coalescing solvent are not compatible up to about 15% by weight, based on the weight of the nonaqueous medium, of a bridging solvent can be added to make the aliphatic solvent and coalescing solvent compatible. Usually 510% by weight of a bridging solvent is used.

Also, it may be desirable to add up to 20% by weight, based on the weight of the nonaqueous medium, of a coalescing solvent which is a solvent for the binder at 250C. The use of these coalescing solvents results in lower binder solids content of the composition and the use of these solvents is kept to a minimum.

Typical aliphatic solvents are petroleum fractions that have a boiling point range of about 1001 600C and may contain up to about 10% by weight of aromatic solvents.

Typical bridging solvents are toluene, xylene, high solvency hydrocarbons having a boiling point range of 1 80-2200C.

Typical coalescing solvents which are solvents for the binder at 500C but not solvents at 250C are as follows: diethylene glycol monohexylether, diethylene glycol 2-ethyl hexyl ether, ethylene glycol monobutylether, 2-ethyl hexanol, isooctylalcohol and other 8 carbon atoms alcohols, slow evaporating high solvency hydrocarbon having a boiling point of 182--2190C, 2-(2-butoxy-ethoxy)isopropanol, 2- (2-m ethoxy-isopropoxy)isopropanol, 2-methoxy isopropanol, 2-propoxy isopropanol, 2-butoxy isopropanol.

Typical coalescing solvents which are solvents for the binder at 250C are as follows: diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether acetate, diethylene glycol 2-ethyl hexyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol 2-ethyl hexyl ether acetate, diethyl phthalate, isobutyrate ester of 2,2,4-trimethyl-1 3-pentanediol and a mixture of methyl esters of succinic acid glutaric acid and adipic acid.

The high solids acrylic polymer dispersion is prepared according to the following process: Step (1) About 5070% by weight of the monomers for Polymer A and the backbone of the graft copolymers, i.e., methyl methacrylate monomers and allyl methacrylate and/or alkyl aminoalkyl methacrylate monomers, are charged into a polymerization vessel with a coalescing solvent such as diethylene glycol monohexyl ether, optionally, a bridging solvent such as toluene and other low boiling solvents such as methanol or a blend of acetone and petroleum ether which control the reflux temperatures of the resulting reaction mixture to less than 950C. The resulting mixture is heated to its reflux, temperature (less than 950C) and held at this temperature for 2-10 minutes.

Step (2) About 0.12% by weight, based on the weight of Polymer A and the backbone of the graft copolymer, of an azo polymerization catalyst, such as azobisisobutyronitrile is added with a coalescing solvent to the reaction mixture and heated to its reflux temperature for about 5-10 minutes;; Step (3) The remaining 3050% by weight of the monomers for Polymer A and the backbone of the graft copolymer and a coalescing solvent such as, diethylene glycol monohexyl ether, and about 0.1-2% by weight, based on the total weight of the monomers for polymer A and the backbone of the graft copolymer, of the aforementioned azo polymerization catalyst with a coalescing solvent as described above are slowly added to the reaction mixture at a uniform rate over a 50-120 minute period while maintaining the reaction mixture at its reflux temperature but below 950C.

Step (4) About 4060% by weight of the monomers such as methyl methacrylate monomers and 2-ethylhexyl acrylate monomers for Copolymer B and the side chains of the graft copolymer and about 0.52% by weight, based on the weight of the above monomers, of a peroxy polymerization catalyst such as t-butyl peroxy pivalate for graft polymer formation are added and the reaction mixture is held at its reflux temperature for about 5-20 minutes; Step (5) The remaining 4060% by weight of the above monomers of step (4) with the above peroxy polymerization catalyst in the same amount are added at a uniform rate over a 20-50 minute period while maintaining the reaction mixture at its reflux temperature;; Step (6) About 210% by weight, based on the weight of the monomers for Polymer A, Copolymer B and the graft copolymer, of methyl methacrylate monomer with about 0.1-1% by weight ot azo polymerization catalyst and the above peroxy polymerization catalyst are added at a uniform rate over a 5-30 minute period and the reaction mixture is held at its reflux temperature for about 10-30 minutes; Step (7) About 1 5-25% by weight, based on the weight of the reaction mixture, of an aliphatic hydrocarbon solvent which is a nonsolvent for Polymer A and the backbone of the graft copolymer is added at a uniform rate over a 40-60 minute period; and Step (8) About 5-1 0% by weight, based on the weight of the reaction mixture, of an aliphatic hydrocarbon solvent of step (7) containing about 0.110% by weight based on the weight of the nonsolvent, of a peroxy polymerization catalyst described above in step (4) are added over a 40-60 minute period and the resulting reaction mixture is cooled to an ambient temperature.

Generally, the coating composition is pigmented. Pigments are usually used in a pigment to binder weight ratio of about 1/100 to about 150/100.

The pigments are introduced into the coating composition by first forming a mill base with a compatible dispersing resin by conventional techniques such as sand grinding, attritor grinding or ball milling. Then the mill base is blended with the film-forming binder as shown in the Examples. Polymers such as those described in Orvis U.S. Patent 3,790,523 issued February 5, 1 974 (Column 2, line 65 Column 3, line 28) and cellulose acetate butyrate can be used as dispersing resins.

The following are examples of the great variety of pigments which are used in the coating composition: metallic oxides, preferably titanium dioxide, zinc oxide, and the like, metal hydroxides, metal flakes, such as aluminum flake, bronze flake, "Afflair" pigments, i.e., mica-coated with titanium dioxide, metal powders, chromates, such as lead chromates, sulfides, sulfates, carbonates, carbon black, silica, talc, china clay, phthalocyanine pigments such as copper phthalocyanine blue, iron blues, organic reds, organic maroons, and other organic pigments.

About 0.1 to 10% by weight, based on the weight of the binder, in addition to the other binder constituents of ultraviolet light stabilizers can be added to the coating composition. Typical ultraviolet light stabilizers are described hereinafter. It may also be desirable to add about 0.15% by weight, based on the weight of the binder, of an antioxidant, described hereinafter, to the coating composition.

About 0.1-5% by weight, based on the weight of the binder, of iron pyrophosphate can be added to the coating composition to improve certain properties of the composition such as improved resistance to deterioration of finishes caused by high humidity. One typically useful iron pyrophosphate is prepared according to the teachings of Jackson U.S. patent 3,074,895 issued January 22, 1 963.

About 0.01-1% by weight, based on the weight of the binder, of silicone anticratering agents can be used such as polyalkene oxide siloxane and silicone glycol copolymers.

The coating composition can contain about 1 5-30% by weight, based on the weight of the binder, of a plasticizer. Typical plasticizers are for example, phthalate esters such as butylbenzyl phthalate, dibutyl phthalate, 2-ethylhexylbenzyl phthalate, dicyclohexyl phthalate, dibenzyl phthalate, butyl cyclohexyl phthalate, di-2-ethylhexyl ester of hexamethylene diphthalate, di(methylcyclohexyl)phthalate. One preferred plasticizer of this group is butylbenzyl phthalate. Other plasticizers that can be used are mixed benzoic acid and fatty oil acid esters of pentaerythritol, poly(propylene adipate)dibenzoate, diethylene glycol dibenzoate, ethylene glycol adipate benzoate and neopentyl glycol adipate benzoate.Other plasticizers are tetrabutylthiodisuccinate, butylphthalyl butyl glycolate, acetyltributyl citrate, dibenzyl sebacate, tricresyl phosphate, toluene ethylsulfonamide.

Preferred plasticizers are coconut oil/ethylene glycol phthalate resins and ethylene glycol phthalate/ethylene glycol benzoate/ethylene glycol adipate resins.

The coating composition of this invention can be applied to a variety of substrates such as metal, e.g., phosphatized steel, uncoated steel, aluminum, fiberglass reinforced with resins, plastics rigid polyurethanes, rigid synthetic rubbers and the like. These substrates are coated with a primer and usually a thin sealer coat is applied over the primer to enhance adhesion of the composition to the primer. Application of the coating composition is done by the usual methods of spraying, electrostatic spraying, dipping, brushing, flow coating and the like. The coating composition can be reduced to an application viscosity by the addition of a coalescing solvent/nonsolvent blend. A typical reducing solvent blend comprises a petroleum naphtha and diethylene glycol monohexyl ether in about a 50/50 weight ratio. Generally, the composition is not reduced below 25% solids based on the binder.

Preferably the composition is reduced to 3035% solids based on binder.

After application, the coating is baked at about 1 50-2250C for 1 5 to 45 minutes. The resulting finish is about 0.1-5 mils thick, preferably, 1-3 mils thick, and has a good gloss. The finish does not yellow on baking and gives a hard, durable, scratch resistant, gasoline-resistant, weather-resistant, alkali-resistant, glossy finish which is suitable for automobile and truck bodies.

Another aspect of this invention is to utilize the composition as a clear coat/color coat finish for substrates. In this finish, a clear coat top layer is in firm adherence to a color coat layer that is in adherence with a substrate. The clear coat is a transparent film of the coating composition of this invention and the color coat is the coating composition of this invention containing pigments in a pigment to binder ratio of about 1/100 to 150/100 and other additives.

Optionally, the color coat can contain about 0.120% by weight, based on the weight of the binder of the color coat, of an ultraviolet light stabilizer. Another option is that the color coat and the clear coat each can contain about 0.520% by weight, based on the weight of the binder of the coat, of an ultraviolet light stabilizer and optionally, about 0.15% by weight, based on the weight of the binder of the coat, of an antioxidant; wherein the weight ratio of ultraviolet light stabilizer to antioxidant is about 1:1 to about 50:1.

Preferred, to form a durable finish, both the clear coat and the color coat contain about 0.58% by weight of an ultraviolet light stabilizer along with about 0.1-1% by weight of the antioxidant.

The thickness of the fully cured color coat and clear coat can vary. Generally, the color coat is about 0.4-1.5 mils thick and preferably 0.6-1.0 mils thick and the clear coat is about 0.5-6.0 mils thick and preferably 0.8-1.5 mils thick.

Any of the aforementioned conventional pigments can be used in the color coat including metallic flake pigments. The clear coat can also contain transparent pigments, i.e., pigments having the same or similar refractive index as the binder of the clear coat and are of a small particle size of about 0.01 550 microns. Typical pigments that can be used in the clear coat in a pigment to binder weight ratio of about 1/1000 to 10/100 are inorganic siliceous pigments, such as silica pigments. These pigments have a refractive index of about 1.4-1.6.

Typical ultraviolet light stabilizers that are useful are as follows: Benzophenones such as hydroxy dodecyloxy benzophenone, 2,4-dihydroxybenzophenone, hydroxybenzophenones containing sulfonic groups and the like.

Triazoles such as 2-phenyl-4-(2',4'-di-hydroxybenzoyl)triazoles, substituted benzotriazoles such as hydroxy-phenyl triazoles and the like.

Triazines such as 3,5-dialkyl-4-hydroxyphenyl derivatives of triazine, sulfur containing derivatives of diallyl-4-hydroxy phenyl triazines, hydroxy phenyl-1 3,5-triazine and the like.

Benzoates such as dibenzoate of diphenylol propane, tertiary butyl benzoate of diphenylol propane, and the like.

Other ultraviolet light stabilizers that can be used include lower alkyl thiomethylene containing phenols, substituted benzenes such as 1 ,3-bis-(2'-hydroxybenzoyl)benzene, metal derivatives of 3,5di-t-butyl-4-hydroxyphenylpropionic acid, asymmetrical oxalic acid diarylamides, alkylhydroxyphenylthioialkanoic acid ester and the like.

Particularly useful ultraviolet light stabilizers that can be used are hindered amines of bipiperidyl derivatives such as those in Murayama et al., U.S. Patent 4,061,616, issued December 6, 1977.

Typical antioxidants that are useful are as follows: tetrakis alkylene(di-alkyl hydroxy aryl)alkyl ester alkanes such as tetrakis methylene 3-(3',5'-dibutyl-4'-hydroxyphenyl)propionate methane, reaction product of p-amino diphenylamine and glycidyl methacrylate, reaction product of n-hexyl-N'phenyl-p-phenylene diamine and glycidyl methacrylate, pentaerythritol tetrakis(thioglycolate), trimethylol propane tris(thioglycolate), trimethylol ethane tris(thioglycoate), N-(4-anilino phenyl)acrylamide and the like.

One preferred combination of ultraviolet light stabilizer and antioxidant is 2-hydroxy-4dodecyloxy benzophenone or a substituted 2-(2-hydroxyphenyl)benzotriazole and tetrakis methylene 3-(3',5'-dibutyl-4'-hydroxyphenyl)propionate methane.

The clear coat/color coat finish is applied by conventional spraying techniques and preferably the clear coat is applied to the color coat while the color coat is still wet. Other conventional application techniques as described above can be used. The finish is then baked at the above temperature.

The following Examples illustrate the invention. All parts and percentages are on a weight basis unless otherwise indicated. All molecular weights are determined by gel permeation chromatography using polymethyl methacrylate as a standard.

Example 1 An acrylic polymer dispersion is prepared as follows: Portion 1 Parts by Weight Methyl methacrylate monomer 151.84 Diethyl aminoethyl methacrylate monomer 2.48 Allyl methacrylate monomer 0.37 Acetone 10.83 Petroleum ether 7.37 Toluene 45.86 Diethylene glycol monohexyl ether 53.88 Portion 2 Solvent of mixed methyl esters of succinic acid, glutaric acid and adipic acid 16.90 Azobisisobutyronitrile 0.74 Portion 3 Methyl methacrylate monomer 98.21 Allyl methacrylate monomer 0.87 Acetone 3.63 Diethylene glycol monohexyl ether 34.16 Petroleum ether 2.50 Solvent of mixed methyl esters of succinic acid, glutaric acid and adipic acid 27.58 Azobisisobutyronitrile 1.22 Portion 4 2-ethylhexyl acrylate monomer 22.93 Methyl methacrylate monomer 5.18 Petroleum ether 4.59 Diethylene glycol monohexyl ether 13.40 75% solution of t-butyl peroxy pivalate in mineral spirits 0.33 Portion 5 2-ethylhexyl acrylate monomer 22.93 Methyl methacrylate monomer 3.44 Petroleum ether 2.29 Diethylene glycol monohexyl ether 13.37 75% solution of t-butyl peroxy pivalate in mineral spirits 0.33 Portion 6 Methyl methacrylate monomer 14.22 Diethylene glycol monohexyl ether 9.27 Azobisisobutyronitrile 0.32 75% solution of t-butyl peroxyl pivalate in mineral spirits 0.16 Portion 7 Aliphatic hydrocarbon (petroleum fraction having essentially the same evaporation rate as mineral spirits but limited to 8% of 8 carbon atom aromatics and above, aniline point measured by ASTM-D 1012-62 of 60 to 670C) 165.09 Portion 8 Aliphatic hydrocarbon (described above) 57.32 75% solution of t-butyl peroxy pivalate in mineral spirits 0.28 Total 787.85 Portion 1 is charged into a reaction vessel equipped with a stirrer, reflux condenser, thermometer, heat source and a nitrogen inlet. During the reaction, the constituents in the vessel are under constant agitation. Portion 1 is heated to its reflux temperature held for 5 minutes at this temperature. The heat source is turn off. The heat resulting from the reaction maintains the reaction temperature of the resulting reaction mixture. Portion 2 is added to the reaction mixture and the mixture is held for 10 minutes at its reaction temperature. Portion 3 is added to the reaction mixture at a uniform rate over a 80 minute period and the the reaction mixture is held at its reaction temperature for an additional 1 5 minutes. Portion 4 is added to and the reaction mixture which is held at its reaction temperature for 1 5 minutes. Portion 5 is added to the reaction mixture at a uniform rate over a 35 minute period. Portion 6 is then added at a uniform rate over a 20 minute period and the reaction mixture is held at its reaction temperature for an additional 20 minutes. Portion 7 is then added at a uniform rate over a 50 minute period. Portion 8 is then added over a 50 minute period and the reaction mixture is cooled to 500C and then filtered.

The resulting acrylic polymer dispersion has a polymer weight solid content of 40% and contains about 35% of a polymer of methyl methacrylate/allyl methacrylate/diethyl aminoethyl methacrylate in a weight ratio of about 98.4/0.6/1.0 and has a weight average molecular weight of about 110,000, 1 5% of a copolymer of 2-ethylhexyl acrylate/methyl methacrylate in a 1/1 weight ratio having a weight average molecular weight of about 30,000 and 50% of a graft copolymer of the above polymer which forms the backbone of the graft copolymer and the above copolymer which forms side chains of the graft copolymer having a weight average molecular weight of about 80,000.

The following mill bases are prepared: White Mill Base Portion 1 Parts by Weight Polymeric dispersant solution (62% polymer solids in toluene in which the polymer comprises methyl methacrylate/2-ethylhexyl acrylate having a number average molecular weight of 4500 and further reacted with mercaptoethanol, a polyisocyanate and ammonia) 8.44 Toluene 11.56 Ethylene glycol monoethyl ether acetate 2.00 Portion 2 Titanium dioxide pigment 68.00 Portion 3 Acrylic polymer dispersion (prepared above 2.00 Portion 4 Hydrocarbon solvent 8.00 Total 100.00 Portion 1 is charged into a mixer and mixed for 5 minutes. Portion 2 is added and mixed for 2 hours and then Portion 3 is added and mixed for 30 minutes. Portion 4 is added and mixed for 30 minutes.The resulting mixture is then ground for one pass through a conventjonal 8 gallon sand mill containing 70 pounds of sand to form a white mill base.

Green Mill Base Portion I Parts by Weight Ethylene glycol monoethylether acetate 10.00 Toluene 20.00 Polymeric dispersant solution (described above) 15.00 Acrylic polymer dispersion (prepared above) 15.00 VM and P Naphtha 25.00 Portion 2 "Monastral" green pigment B (phthalocyanine pigment) 15.00 Total 100.00 Portion 1 is premixed and then Portion 2 is added and the resulting composition is ground two passes in a conventional 8 gallon sand mill containing 70 pounds of sand at the rate of 30 gallons per minute to form a dispersion.

Yellow Mill Base Portion 1 Parts by Weight Polymeric dispersant solution (described above) 28.40 Toluene 12.60 Portion 2 Ferrite Yellow Pigment (iron oxide pigment) 46.00 Portion3 Acrylic polymer dispersion (prepared above) 3.00 VM and P Naphtha 10.00 Total 100.00 Portion 1 is charged into a mixing vessel and mixed for 10 minutes and then Portion 2 is added and mixed for 1 hour. Portion 3 is added and mixed for 10 minutes and then Portion 4 is added and mixed for 30 minutes. The resulting mixture is charged into sand mill, described above, and ground for one pass to form a dispersion.

Blue Mill Base Portion 1 Parts by Weight Polymeric dispersant solution (described above) 15.00 Toluene 36.00 Portion 2 "Monastral" blue flake (phthalocyanine pigment) 15.00 Portion 3 Acrylic polymer dispersion (prepared above) 20.00 Portion 4 VM and P Naphtha 14.00 Total 100.00 Portion 1 is charged into a mixing vessel and mixed for 10 minutes and then Portion 2 is added and mixed for 30 minutes. Portion 3 is added and mixed for 30 minutes and portion 4 then is added and mixed for 30 minutes. The resulting mixture is charged to a conventional said mill,described above, and ground for two passes to form a dispersion.

Black Mill Base Portion 1 Parts by Weight Polymeric dispersant solution (described above) 38.00 Toluene 17.00 VM and P Naphtha 20.00 Acrylic Polymer dispersion (described above) 5.00 Portion 2 Carbon black pigment 20.00 Total 100.00 Portion 1 is premixed and Portion 2 is added and the resulting mixture is charged into an attritor containing 1/8 inch steel balls as the grinding media and ground for 3 hours to a 0.5 mil fineness.

Aluminum Mill Base Portion 1 Parts by Weight Polyester resin plasticizer (85% of a polyester resin of ethylene glycol adipate/ethylene glycol benzoate/ethylene glycol phthalate having an acid No. of less than 10 and 15% of butylbenzyl phthalate) 11.50 Toluene 8.50 Acrylic polymer dispersion (prepared above) 15.00 Portion 2 Aluminum flake paste (65% solids aluminum flake in aliphatic solvent) 12.50 Portion 3 Acrylic polymer resin dispersion (described above) 52.50 Total 100.00 Portion 1 is charged into a mixing vessel and mixed for 5 minutes. Portion 2 is added and mixed for 1 hour and then Portion 3 is added and mixed for 3 hours to form a dispersion.

A white high solids acrylic dispersion lacquer is formed as follows: Portion 1 Parts by Weight Acrylic polymer dispersion (prepared above) 625.93 Polyester resin plasticizer solution (described above) 25.73 Alkyd resin plasticizer solution (85% of a coconut oil/ethylene glycol phthalate resin having an acid No. less than 10 and 15% butyl benzyl phthalate) 25.73 Butyl benzyl phthalate 18.01 Flow control agent (1% solution of light weight silicone oil in xylene) 0.29 Portion 2 White Mill Base (prepared above) 190.16 Yellow Mill Base (prepared above) 0.86 Black Mill Base (prepared above) 0.29 Total 887.00 Portion 1 is charged into a mixing vessel and mixed for 5 minutes and then Portion 2 is added and mixed for 1 hour to form the lacquer.

The above lacquer is reduced to a 34% volume solids by mixing the lacquer with the following thinner: Parts by Weight Petroleum naphtha 50.00 Diethylene glycol monohexyl ether 50.00 Total 100.00 The reduced lacquer is sprayed into phosphatized steel panels primed with an alkyd resin primer and coated with a sealer. Three coats are sprayed onto the panels and the panels are baked at about 1 650C for 30 minutes to provide a finish that is about 2.2 mils thick. The resulting finish is smooth, glossy, water resistant, gasoline resistant, chip resistant, weatherable and has excellent distinctness of image. The lacquer is useful as a high quality automotive finish.

A blue metallic high solids acrylic dispersion lacquer is formed as follows: Portion 1 Parts by Weight Hydrocarbon solvent (described above) 25.05 Acrylic polymer dispersion (prepared above) 616.59 Polyester resin plasticizer solution (described above) 28.55 Alkyd resin plasticizer solution (described above) 34.41 Butyl benzyl phthalate 27.23 2-hydroxyl-4-dodecyloxy benzophenone 1.70 Flow control agent (described above) 0.24 Portion 2 Aluminum Mill Base (prepared above) 50.89 Blue Mill Base (prepared above) 10.80 Black Mill Base (prepared above) 0.32 Green Mill Base (prepared above) 0.22 Total 796.00 The above lacquer is reduced to a 34% volume solids by mixing the lacquer with the above thinner. The reduced lacquer is sprayed onto phosphatized steel panels primed and sealed as described above using the same spraying procedures and then the coated panels are baked under the above: conditions giving a finish about 2.2 mils in thickness having the same properties as above including excellent metallic glamour. The lacquer is useful as a high quality automotive finish.

Example 2 An acrylic polymer dispersion is prepared as follows: Portion 1 Parts by Weight Methyl methacrylate monomer 627.1 Diethyl aminoethyl methacrylate monomer 10.8 Allyl methacrylate monomer 1.6 Methanol 35.0 Toluene 200.0 2-ethyl hexanol 268.3 Portion 2 Methyl methacrylate monomer 35.0 Azobisisobutyronitrile 3.3 Portion 3 Methyl methacrylate monomer 428.3 Allyl methacrylate monomer 3.8 Methanol 40.0 Isobutyrate ester of 2,2,4-trimethyl-1 ,3-pentanediol 310.0 Azobisisobutyronitrile 5.3 Portion 4 2-ethylhexyl acrylate monomer 100.0 Methyl methacrylate monomer 22.5 Methanol 15.0 Isobutyrate ester of 2,2,4-trimethyl- 1 3-pentanediol 62.1 75% solutuon of t-butylperoxy pivalate in mineral spirits 1.5 Portion 5 2-ethylhexyl acrylate monomer 100.0 Methyl methacrylate monomer 15.0 2-ethyl hexanol 55.0 75% solution of t-butylperoxy pivalate in mineral spirits 1.5 Portion 6 Methyl methacrylate monomer 62.1 2-ethyl hexanol 40.0 Azobisisobutyronitrile 1.4 75% solution of t-butylperoxy pivalate in mineral spirits 0.7 Portion 7 Aliphatic hydrocarbon (petroleum fraction having essentially the same evaporation rate as mineral spirits but limited to 8% of 8 carbon atom aromatics and above, aniline point measured by ASTM-D 1012-62 of 60 to 670C) 770.0 Portion 8 Aliphatic hydrocarbon (described above) 200.0 75% solution of t-butyl peroxy pivalate in mineral spirits 1.2 Total 3416.5 Portion 1 is charged into a reaction vessel equipped with a stirrer, reflux condenser, thermometer, heat source and a nitrogen inlet. During the reaction, the constituents in the vessel are under constant agitation. Portion 1 is heated to its reflux temperature and held for 5 minutes at this temperature. The heat source is turned off.The heat resulting from the reaction maintains the temperature of the reaction mixture. Portion 2 is added to the reaction mixture and the mixture is held for 10 minutes at this reaction temperature. Portion 3 is added to the reaction mixture at a uniform rate over a 90 minute period and then the reaction mixture is held at its reaction temperature for 1 5 minutes. Portion 4 is added to the reaction mixture and held at its reaction temperature for 1 5 minutes. Portion 5 is added to the reaction mixture at a uniform rate over a 35 minute period. Portion 6 is then added at a uniform rate over a 20 minute period and held at its reaction temperature for an additional 20 minutes. Portion 7 is then added at a uniform rate over a 50 minute period.Portion 8 is then added over a 50 minute period and the reaction mixture is cooled to 500C and then filtered.

The resulting acrylic polymer dispersion has a polymer weight solids content of 40% and containins about 35% of a polymer of methyl methacrylate/allyl methacrylate/diethyl aminoethyl methacrylate in a weight ratio of about 98.4/0.6/1.0 and has a weight average molecular weight of about 110,000, 1 5% of a copolymer of 2-ethylhexyl acrylate/methyl methacrylate in a 1/1 weight ratio having a weight average molecular weight of about 30,000 and 50% of a graft copolymer of the above polymer which forms the backbone of the graft copolymer and the above copolymer which forms side chains of the graft copolymer having a weight average molecular weight of about 80,000.

A blue metallic high solids acrylic dispersion lacquer is formed using the same constituents as used in Example 1 except the above prepared acrylic polymer dispersion is substituted for the acrylic polymer dispersion of Example 1. The lacquer is reduced as in Example 1, spray applied to phosphatized primed and sealed steel panels described in Example 1 and baked under the same conditions as in Example 1. The resulting finish is about 2.2 mils thick and has the same properties as the finish of Example 1 including excellent metallic glamour.

Claims (15)

Claims

1. A high solids acrylic dispersion lacquer coating composition having an acrylic polymer binder content of about 25- 45% by weight in a nonaqueous medium; wherein the acrylic polymer binder consists essentially of (1) Polymer A comprising polymerized methyl methacrylate and a polymerized monomer selected from the group consisting of allyl methacrylate, alkyl amino alkyl methacrylate or mixtures thereof and having a weight average molecular weight, measured by gel permeation chromatography, of about 90,000-130,000; (2) Copolymer B comprising polymerized methyl methacrylate and an alkyl acrylate having 6-1 2 carbon atoms in the alkyl group and having a weight average molecular weight, measured as above, of about 20,000-40,000;; and (3) a graft copolymer of Polymer A which forms a backbone of the graft copolymer and Copolymer B attached to the backbone which forms side chains of the graft copolymer; and wherein the nonaqueous medium comprises (a) an aliphatic solvent which is at 250C a nonsolvent for Polymer A and a solvent for Copolymer B; and (b) a coalescing solvent which at 500C is a solvent for the binder and at 250C is a nonsolvent for the binder.

2. The coating composition of Claim 1 containing pigment in a pigment to binder weight ratio of about 1/100 to 150/100.

3. The coating composition of Claim 1 or 2 in which Polymer A consists essentially of methyl methacrylate, allyl methacrylate and diethyl amino methacrylate.

4. The coating composition of Claim 1,2 or 3 in which Copolymer B consists essentially of methyl methacrylate and 2-ethylhexyl acrylate.

5. The coating composition of Claim 1, 2, 3 or 4 in which Polymer A consists essentially of 9099.5% by weight of methyl methacrylate, 0.1-5% by weight of allyl methacrylate and 0.45% by weight of diethyl amino ethyl methacrylate and having a weight average molecular weight of about 100,000-115,000.

6. The coating composition of any of Claims 1 to 5 in which Copolymer B consists essentially of about 4060% by weight of methyl methacrylate and 4060% by weight of 2-ethylhexyl acrylate and has a weight average molecular weight of about 20,000-40,000.

7. The coating composition of any of Claims 1 to 6 containing about 1 5-30% by weight, based on the weight of the composition, of a plasticizer.

8. The coating composition of Claim 7 in which the plasticizer is selected from the group consisting of butyl benzyl phthalate, coconut oil/ethylene glycol phthalate resin or an ethylene glycol phthalate/ethylene glycol benzoate/ethylene glycol adipate resin.

9. The coating composition of any of Claims 1 to 8 wherein the nonaqueous medium comprises about (a) 3565% by weight, based on the weight of the nonaqueous medium of an aliphatic solvent; and (b) 3565% by weight of coalescing solvent.

10. The high solids acrylic dispersion lacquers coating composition of any of Claims 1 to 9 containing pigment in a pigment to binder ratio of about 1/100-1 50/100 and in which the acrylic polymer consists essentially of (1) Polymer A consisting essentially of 90-99.5% by weight, based on the weight of Polymer A, of methyl methacrylate, 0.1-5% by weight of allyl methacrylate and O.'i 5% by weight of diethyl aminoethyl methacrylate and has a weight average molecular weight of about 100,000-11 5,000;; (2) Copolymer B consisting essentially of 4060% by weight, based on the weight of Copolymer B, of methyl methacrylate and 4060%, based on the weight of Copolymer B, of 2-ethylhexyl acrylate and has a weight average molecular weight of about 20,000-40,000; (3) a graft copolymer of Polymer A which forms the backbone of the graft copolymer and Copolymer B which forms the side chains of the graft copolymer; and contains about 1530% by weight, based on the weight of the composition, of an organic plasticizer; wherein the nonaqueous medium comprises about (a) 3565%, based on the weight of the nonaqueous medium, of an aliphatic nonsolvent for Polymer A and a solvent for Copolymer B which is a petroleum fraction having a boiling point of about 100-1 600C; (b) 3565% by weight, based on the weight of the nonaqueous medium of a coalescing solvent of diethylene glycol monohexyl ether.

11. The coating composition of Claim 10 containing up to about 15% by weight based on the weight of the nonaqueous medium, of a bridging solvent comprising toluene.

12. A process for preparing the high solids acrylic dispersion lacquers of Claim 1 which comprises the following steps: Step (1) polymerizing about 5070% by weight of the monomers of Polymer A and backbone of graft copolymer in the presence of an azo polymerization catalyst and a coalescing solvent, and a solvent selected from the group consisting of methanol or a blend of a low boiling ketone and a petroleum ether solvents while maintaining a temperature of 85-950C; Step (2) adding the remaining 30-50% by weight of the monomer of Polymer A and backbone of graft copolymer at a uniform rate and polymerizing said monomers.

Step (3) adding about 4060% by weight of the monomers of Copolymer B and the side chains of the graft copolymer and a peroxy polymerization catalyst and polymerizing said monomers; Step (4) adding at a uniform rate the remaining 4060% by weight of the monomers of Copolymer B and the side chains of the graft copolymer and a peroxy polymerization catalyst and polymerizing said monomers to form Copolymer B and a graft copolymer having a backbone of Polymer A and side chains of Copolymer B; Step (5) adding sufficient aliphatic nonsolvents for Polymer A to form a dispersion.

13. Any coating composition as claimed in Claim 1 substantially as described in the foregoing "Examples" section.

14. Any process as claimed in Claim 12 substantially as described in the foregoing "Examples" section.

15. A coating composition prepared by a process as claimed in Claim 12 or 14.