CA1212794A - High solids color coat containing alcohol soluble cellulose acetate butyrate - Google Patents
High solids color coat containing alcohol soluble cellulose acetate butyrateInfo
- Publication number
- CA1212794A CA1212794A CA000446455A CA446455A CA1212794A CA 1212794 A CA1212794 A CA 1212794A CA 000446455 A CA000446455 A CA 000446455A CA 446455 A CA446455 A CA 446455A CA 1212794 A CA1212794 A CA 1212794A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- binder
- acrylic polymer
- coating composition
- color coat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Paints Or Removers (AREA)
Abstract
TITLE
High Solids Color Coat Containing Alcohol Soluble Cellulose Acetate Butyrate ABSTRACT OF THE DISCLOSURE
The coating composition useful as the exterior finish on automobiles and trucks contains about 25-50%
by weight of a binder of film-forming constituents and 50-75% by weight of a volatile organic solvent carrier and additionally contains 2-150% by weight, based on the weight of the binder, of pigment; the binder is about 20-70% by weight of an acrylic polymer containing reactive hydroxyl, carboxyl, amide groups or any mixture of such groups, about 0-40% by weight of a hydroxy-terminated polyester urethane resin and about 25-40%
by weight of an alkylated melamine formaldehyde cross-linking resin; in addition the composition contains about 4-20% by weight, based on the weight of the binder, of a rheology control agent of an alcohol soluble cellu-lose acetate butyrate having a buryryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second.
High Solids Color Coat Containing Alcohol Soluble Cellulose Acetate Butyrate ABSTRACT OF THE DISCLOSURE
The coating composition useful as the exterior finish on automobiles and trucks contains about 25-50%
by weight of a binder of film-forming constituents and 50-75% by weight of a volatile organic solvent carrier and additionally contains 2-150% by weight, based on the weight of the binder, of pigment; the binder is about 20-70% by weight of an acrylic polymer containing reactive hydroxyl, carboxyl, amide groups or any mixture of such groups, about 0-40% by weight of a hydroxy-terminated polyester urethane resin and about 25-40%
by weight of an alkylated melamine formaldehyde cross-linking resin; in addition the composition contains about 4-20% by weight, based on the weight of the binder, of a rheology control agent of an alcohol soluble cellu-lose acetate butyrate having a buryryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second.
Description
~2~ 4 TITLE
~ligh Solids Color Coat Containing Alcohol Soluble Cellulose Acetate Butyrate BACKGROUND OF THE INVENTION
5This invention is related to a color coat/
clear coat finish oE high solids coating compositions, in particular, to mottle and strike-in resistant high solids color coat compositions containing as a rheology control additive an alcohol soluble cellulose acetate butyrate-Conventional enamel coating composltions of ahigh molecular weight acrylic polymer and melamine cross-linking resin are well known in the art as shown by Vasta U.S, Patent 3,622,651, issued November 23, 1971;
Hick U.S. Patent 3,841,895, issued October 15, 1974;
Parter U.S. Patent 3,674,734, issued July 4, 1972; and Parker U.S. Patent 3,637,546, issued January 25l 1972.
These patents illustrate high quality coating composi-tions. However, these compositions have a relatively low solids content to provide for good application properties and good properties of the resulting dried finish. To utilize these compositions in areas which have strict air pollution regulations, pollution abate-ment equipment is required. This equipment is expensive and increases capital investment of a plant and is costly to operate. Attempts to reduce the solvent con-tent of these conventional compositions generally have been unsuccessful.
Color coat/clear coat finishes have been developed in recent years as a topcoat system for auto-mobiles and other industrial articles which give appear ance superior to conventional "unifinish" enamels. Color ~æ~ls~
coat/clear enamels are two-layer finishes consist-ing of a pigmented basecoat overcoated with a trans parent clearO The clear is usually applied to the wet basecoat after a short solvent flash period, and the color coat/clear coat coating is then baked to cure both layers simultaneously. The clear coat imparts a smooth-ness, depth and clarity to the color coat/clear coat enamel which cannot be obtained in a "unifinish" enamel contai.ning pigment throughout its thickness. The superior appearance of color coat/clear coat enamels is especially pronounced in metallic finishes containing aluminum flake, because this relatively large pigment tends to reduce the surface smoothness and gloss of con-ventional enamels whereas in color coat/clear coat enamels t.he metallic basecoat is overcoated with a smooth clear.
Formulation of acceptable color coat/clear coat coatings requires the solution of two problems peculiar to these finishes. A problem in metallic base-coats is the pronounced tendency of aluminum flakes, atthe high concentrations needed for hiding at the 0.5-1 mil dry film thickness used, to assume different orientations in the cured basecoat film depending on film thickness and application conditions, resulting in large scale mottling, a blotchy appearance~ and an un-acceptable variation of brightness and color with color coat film thickness. A problem in both metalli.c and solid color coat/clear coat finishes is the tendency of solvents from the clear coat applied over the wet basecoat to diffuse into the basecoat and remobilize the pigments in it, resulting in mottling of metallic f$~
basecoats and color change in both metallic and solid color basecoats. This phenomenon is referred to as "strike-in" of the clear.
These problems have been overcome in low solids acrylic/melamine and polyester/melamine color coats by incorporating a high molecular weight cellulose acetate butyrate, of a type conventionally used in finishes for metallic flake control, into the basecoat binder, as exemplified in an article by K. Walker titled "Wet-On-Wet Coatings" in Polymers Paint and Colour Journalr October 17, 1979. However, because of the high molecular weight of the cellulose acetate butyrate em-ployed, these basecoats must be spray-applied at very low solids contents in the range of 12-15 weight percent.
In an effort to obtain high solids color coat/-clear coat coating compositions that meet current or anticipated air pollution regulations and can be applied by conventional spraying techni~ues, the molecular weight of the acrylic polymer used in these compositions was reduced substantially, resulting in a reduction in the basecoat solvent content. These higher solids color coat/clear coat enamels had much poorer mottle resist-ance and color uniformity, which could not be corrected by addition of the aforementioned high molecular weiqht cellulose acetate butyrate resins to the basecoat with-out reducing its spray solids content to unacceptably low levels.
There is a need for high solids color coating compositions that provide a low viscosity under typical spraying conditions when the coatinq compositions are applied and provide a substantially increased viscosity after application to prevent mottling and color varia-tions. High solids color coat compositions containing /, , .. ~
~æ7~
rheology control additives of this invention have sueh properties and have an overall appearance acceptable for exterior finishes of automobilies and trucks and other industrial articles.
_ MARY OF THE INVENTION
An acrylic color coat enamel coating composition has now been developed having about 25-50%
by weight of a binder of film-forming constituents and 50-75% by weight of a volatile organie solvent carrier at spray viscosity and containing in addition about
~ligh Solids Color Coat Containing Alcohol Soluble Cellulose Acetate Butyrate BACKGROUND OF THE INVENTION
5This invention is related to a color coat/
clear coat finish oE high solids coating compositions, in particular, to mottle and strike-in resistant high solids color coat compositions containing as a rheology control additive an alcohol soluble cellulose acetate butyrate-Conventional enamel coating composltions of ahigh molecular weight acrylic polymer and melamine cross-linking resin are well known in the art as shown by Vasta U.S, Patent 3,622,651, issued November 23, 1971;
Hick U.S. Patent 3,841,895, issued October 15, 1974;
Parter U.S. Patent 3,674,734, issued July 4, 1972; and Parker U.S. Patent 3,637,546, issued January 25l 1972.
These patents illustrate high quality coating composi-tions. However, these compositions have a relatively low solids content to provide for good application properties and good properties of the resulting dried finish. To utilize these compositions in areas which have strict air pollution regulations, pollution abate-ment equipment is required. This equipment is expensive and increases capital investment of a plant and is costly to operate. Attempts to reduce the solvent con-tent of these conventional compositions generally have been unsuccessful.
Color coat/clear coat finishes have been developed in recent years as a topcoat system for auto-mobiles and other industrial articles which give appear ance superior to conventional "unifinish" enamels. Color ~æ~ls~
coat/clear enamels are two-layer finishes consist-ing of a pigmented basecoat overcoated with a trans parent clearO The clear is usually applied to the wet basecoat after a short solvent flash period, and the color coat/clear coat coating is then baked to cure both layers simultaneously. The clear coat imparts a smooth-ness, depth and clarity to the color coat/clear coat enamel which cannot be obtained in a "unifinish" enamel contai.ning pigment throughout its thickness. The superior appearance of color coat/clear coat enamels is especially pronounced in metallic finishes containing aluminum flake, because this relatively large pigment tends to reduce the surface smoothness and gloss of con-ventional enamels whereas in color coat/clear coat enamels t.he metallic basecoat is overcoated with a smooth clear.
Formulation of acceptable color coat/clear coat coatings requires the solution of two problems peculiar to these finishes. A problem in metallic base-coats is the pronounced tendency of aluminum flakes, atthe high concentrations needed for hiding at the 0.5-1 mil dry film thickness used, to assume different orientations in the cured basecoat film depending on film thickness and application conditions, resulting in large scale mottling, a blotchy appearance~ and an un-acceptable variation of brightness and color with color coat film thickness. A problem in both metalli.c and solid color coat/clear coat finishes is the tendency of solvents from the clear coat applied over the wet basecoat to diffuse into the basecoat and remobilize the pigments in it, resulting in mottling of metallic f$~
basecoats and color change in both metallic and solid color basecoats. This phenomenon is referred to as "strike-in" of the clear.
These problems have been overcome in low solids acrylic/melamine and polyester/melamine color coats by incorporating a high molecular weight cellulose acetate butyrate, of a type conventionally used in finishes for metallic flake control, into the basecoat binder, as exemplified in an article by K. Walker titled "Wet-On-Wet Coatings" in Polymers Paint and Colour Journalr October 17, 1979. However, because of the high molecular weight of the cellulose acetate butyrate em-ployed, these basecoats must be spray-applied at very low solids contents in the range of 12-15 weight percent.
In an effort to obtain high solids color coat/-clear coat coating compositions that meet current or anticipated air pollution regulations and can be applied by conventional spraying techni~ues, the molecular weight of the acrylic polymer used in these compositions was reduced substantially, resulting in a reduction in the basecoat solvent content. These higher solids color coat/clear coat enamels had much poorer mottle resist-ance and color uniformity, which could not be corrected by addition of the aforementioned high molecular weiqht cellulose acetate butyrate resins to the basecoat with-out reducing its spray solids content to unacceptably low levels.
There is a need for high solids color coating compositions that provide a low viscosity under typical spraying conditions when the coatinq compositions are applied and provide a substantially increased viscosity after application to prevent mottling and color varia-tions. High solids color coat compositions containing /, , .. ~
~æ7~
rheology control additives of this invention have sueh properties and have an overall appearance acceptable for exterior finishes of automobilies and trucks and other industrial articles.
_ MARY OF THE INVENTION
An acrylic color coat enamel coating composition has now been developed having about 25-50%
by weight of a binder of film-forming constituents and 50-75% by weight of a volatile organie solvent carrier at spray viscosity and containing in addition about
2-150% by weight, based on the weight of the binder, of pigment; the binder having about 20-70% by weight , based on the weight of the binder, of an acrylic polymer containing reactive hydroxyl groups, carboxyl groups, amide groups, or any mixture of such groups, about 0.4-%
by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resinl about 25=40% by weight~ based on the weight of the binder, of any alkylated melamine formaldehyde erosslinking agent and about 4-20% by weight, based on the weight of the binder, or a rheology eontrol agent which consists essentially of an aleohol soluble eellulose aeetate butyrate having a butyryl eontent of about 45-50% by weight, a hydroxyl eontent of about 4-5% by weight and a viscosity of about 0.2-0.4 seeond.
DESCRIPTION OF THE INVENTION
It has now been found that aleohol soluble eellulose aeetate butyrate is an effeetive rheology eon-trol agent in high solids eolor eoat/elear coat eoat-ings. When added to the base eolor eoat, the rheologycontrol agent of this inven-tion permits coatings of uniform color to be applied over a broader range of film thicknesses and application conditions (greater appli-cation latitude) and gives freedom from resolubilization of the color coat by the clear coat ~strike-in) causing ,~
. ~
7~
pigments to become mobile again and change the color of the coatins. The rheology control a~ent of this inven-tion is especially ~ffective as aluminum 1ake control agent in metallic color coats where, in addition to the above-mentioned advantages, it prevents color nonuni-formities known as mottling and gives high metallic brightness.
The high solids color coat coating composition of this invention has a binder content of film-forming constituents of about 25-50% by weight. Preferably, the composition has a binder content of about 28-45~. The composition contains about 50-75% by weight of a vola-tile organic sol~ent carrier which generally is a sol-vent Eor the binder. The binder contains 4-20% by weight of a rheology control agent. The composition contains about 2-150% by weight of pigment based on the weight of the binder.
The rheology or flake control agent is an alcohol soluble butyrate, a grade of cellulose acetate butyrate (Eastman CAB-533-0.4), hereinafter referred to - as ASB. ASB has a butyryl content of about ~15-5G% by weight, a hydroxyl content of about 4-5% by weight and viscosity vf about 0.2-0.4 second measured accordir.g to ~STM
Method D-1343 in the solution described as Formula ~, ASTM Method D-817. In order to maximize the sollds content and minimize the solvent content of the color coat enamels, it is preferred to use ASB having a vis-cosity of about a . 2-0.3 second. Because of its high hydroxyl content, ASB crosslinks with the melamine resin when the coaling is haked, forming an integral part of the binder.
The solubility properties of ASB are markedly different from those of normal finishes grades of cellu-lose acetate butyrate. ASB forms low viscosity solu-tions in low molecular weight alcohols, ketones and glycol ethers, and in blends of aromatic hydrocarbonswith minor amounts of ethanol but yields extremely high viscosity solutions in slow solvents such as methyl n-amyl ketone, a principal slow solvent in basecoat enamel. Its solubility properties differ markedly from those of normal finishes grac1es of cellulose acetate butyrate, such as Eastman's CAB-381-0.5 and CAB-531-1, as shoen by the following comparison of solution viscosities:
lO ASB Solution Viscosity of Viscosity of ~SB Viscosity 15% CAB-387-0.5 15% CAB-531-1 SolventConc'n Centipoises Solution, Cps. Solution, CpS.
Methanol 15% 52 Insoluble Insoluble Ethanol 15% 205 Insoluble Insoluble Methyl ethyl ketone 15% 138 80 170 ~thylene glycol monoethyl ether 15% 235 700 950 n-Butyl acetate 10% >100,000 272 585 Methyl n-amyl ketone 10%>100,000 267 577 Toluene -Insoluble Gel Insoluble Toluene/95%
ethanol (80/20 blend) 15%130 90 150 It is desirable to formulate color coat enamels in a blend of volatile, strong solvents for ASB
with a slower evaporating, poor solvents for ASB to obtain low viscosity and high spray so]ids and rapid set-up after application. When fast strong ASB solvents evaporate rapidly on application of the color coat, ASB
forms a viscous solution in slow poor solvents and "gels" the color coat. This allows the color coat to remain fluid and few seconds after application to obtain flow-out.
.
~L2~ 33~
but then sets up -the colol coat rapidly to prevent further differential movement of al.uminum flakes in metallic colors. If no slower evaporating, stong ASB
solvents are present in the clear coatp AS~ in the color coat prevents strike-in of solvents from the clear coat into the wet basecoat which can resul~ in remobilization of aluminum flake and other pigments. ASB is conveniently introduced as a 30% solution in 1:1 by weight ethanol/methyl n-amyl ketone or 1:1 by weight ethanol/methyl ethyl ketone.
The advantages of high solids color coat coating compositions that contain the rheology control additive are as follows: the composition can be sprayed on vertical surfaces without sagging and running on the substrate to which it was applied; the resulting finish has excellent gloss and image definition (smoothness);
when metallic flakes are used in the composition, the flakes are more properly oriented and :more uniformly dispersed in the finish with an improved brightness and ~ with less or no evidence of mottli.ng caused by differential orientation of the metallic flakes.
The principal binder of the composition is an acrylic polymer having carboxyl, hydroxyl or amide groups, a weight average molecular weight of about 2500-25,000 and a glass transition temperature of about -20C to +25C.
Typically useful acrylic polymers contain alkyl methacrylate, alkyl acrylate, hydroxyalkyl acrylate, hydroxyalkyl methacylate and can contain styrene, acrylic acid or methacrylic acid. Amide monomers such as methyacrylamide and acrylamide can be used; glycidyl monomers such as glycidyl acrylate or glycidyl methacrylate can also be used.
9~
Preferred acrylic po]ymers are of an alkyl methacrylate that has 1-18 carbon atoms in the alkyl 9L'OUp, an alkyl acrylate that has 1-18 carbon atoms in the alkyl group and a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl group. To form an acrylic polymer which has a hydroxyl content of about 2-6% by weight, a sufficient amount of the aforementioned hydroxyalkyl acrylate or methacrylate is utilized. The polymer also can contain small amounts of ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, itaconic acid, in amounts of about 0.1-5% by weight.
Typical alkyl methacrylates and acrylates that can be used to prepare the acrylic polymers are: methyl methyacrylate, ethyl methacrylatel butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, propyl methacrylate, phenyl methaerylate, isobornyl methacry-late, methyl aerylate, ethyl aerylate, propyl aerylate,isopropyl aerylate, butyl aerylate, isobutyl aerylate, hexyl aerylate, 2-ethylhexyl aerylate, nonyl aerylate, lauryl aerylate, stearyl acrylate, eyelohexyl aerylate, isodecyl aerylate, phenyl aerylate~ isobornyl aerylate, and the like.
Adhesion promoting monomers ean also be used in the aerylie polymers sueh as diethyl aminoethyl methaerylate, tertiary butyl aminoethyl methaerylate,
by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resinl about 25=40% by weight~ based on the weight of the binder, of any alkylated melamine formaldehyde erosslinking agent and about 4-20% by weight, based on the weight of the binder, or a rheology eontrol agent which consists essentially of an aleohol soluble eellulose aeetate butyrate having a butyryl eontent of about 45-50% by weight, a hydroxyl eontent of about 4-5% by weight and a viscosity of about 0.2-0.4 seeond.
DESCRIPTION OF THE INVENTION
It has now been found that aleohol soluble eellulose aeetate butyrate is an effeetive rheology eon-trol agent in high solids eolor eoat/elear coat eoat-ings. When added to the base eolor eoat, the rheologycontrol agent of this inven-tion permits coatings of uniform color to be applied over a broader range of film thicknesses and application conditions (greater appli-cation latitude) and gives freedom from resolubilization of the color coat by the clear coat ~strike-in) causing ,~
. ~
7~
pigments to become mobile again and change the color of the coatins. The rheology control a~ent of this inven-tion is especially ~ffective as aluminum 1ake control agent in metallic color coats where, in addition to the above-mentioned advantages, it prevents color nonuni-formities known as mottling and gives high metallic brightness.
The high solids color coat coating composition of this invention has a binder content of film-forming constituents of about 25-50% by weight. Preferably, the composition has a binder content of about 28-45~. The composition contains about 50-75% by weight of a vola-tile organic sol~ent carrier which generally is a sol-vent Eor the binder. The binder contains 4-20% by weight of a rheology control agent. The composition contains about 2-150% by weight of pigment based on the weight of the binder.
The rheology or flake control agent is an alcohol soluble butyrate, a grade of cellulose acetate butyrate (Eastman CAB-533-0.4), hereinafter referred to - as ASB. ASB has a butyryl content of about ~15-5G% by weight, a hydroxyl content of about 4-5% by weight and viscosity vf about 0.2-0.4 second measured accordir.g to ~STM
Method D-1343 in the solution described as Formula ~, ASTM Method D-817. In order to maximize the sollds content and minimize the solvent content of the color coat enamels, it is preferred to use ASB having a vis-cosity of about a . 2-0.3 second. Because of its high hydroxyl content, ASB crosslinks with the melamine resin when the coaling is haked, forming an integral part of the binder.
The solubility properties of ASB are markedly different from those of normal finishes grades of cellu-lose acetate butyrate. ASB forms low viscosity solu-tions in low molecular weight alcohols, ketones and glycol ethers, and in blends of aromatic hydrocarbonswith minor amounts of ethanol but yields extremely high viscosity solutions in slow solvents such as methyl n-amyl ketone, a principal slow solvent in basecoat enamel. Its solubility properties differ markedly from those of normal finishes grac1es of cellulose acetate butyrate, such as Eastman's CAB-381-0.5 and CAB-531-1, as shoen by the following comparison of solution viscosities:
lO ASB Solution Viscosity of Viscosity of ~SB Viscosity 15% CAB-387-0.5 15% CAB-531-1 SolventConc'n Centipoises Solution, Cps. Solution, CpS.
Methanol 15% 52 Insoluble Insoluble Ethanol 15% 205 Insoluble Insoluble Methyl ethyl ketone 15% 138 80 170 ~thylene glycol monoethyl ether 15% 235 700 950 n-Butyl acetate 10% >100,000 272 585 Methyl n-amyl ketone 10%>100,000 267 577 Toluene -Insoluble Gel Insoluble Toluene/95%
ethanol (80/20 blend) 15%130 90 150 It is desirable to formulate color coat enamels in a blend of volatile, strong solvents for ASB
with a slower evaporating, poor solvents for ASB to obtain low viscosity and high spray so]ids and rapid set-up after application. When fast strong ASB solvents evaporate rapidly on application of the color coat, ASB
forms a viscous solution in slow poor solvents and "gels" the color coat. This allows the color coat to remain fluid and few seconds after application to obtain flow-out.
.
~L2~ 33~
but then sets up -the colol coat rapidly to prevent further differential movement of al.uminum flakes in metallic colors. If no slower evaporating, stong ASB
solvents are present in the clear coatp AS~ in the color coat prevents strike-in of solvents from the clear coat into the wet basecoat which can resul~ in remobilization of aluminum flake and other pigments. ASB is conveniently introduced as a 30% solution in 1:1 by weight ethanol/methyl n-amyl ketone or 1:1 by weight ethanol/methyl ethyl ketone.
The advantages of high solids color coat coating compositions that contain the rheology control additive are as follows: the composition can be sprayed on vertical surfaces without sagging and running on the substrate to which it was applied; the resulting finish has excellent gloss and image definition (smoothness);
when metallic flakes are used in the composition, the flakes are more properly oriented and :more uniformly dispersed in the finish with an improved brightness and ~ with less or no evidence of mottli.ng caused by differential orientation of the metallic flakes.
The principal binder of the composition is an acrylic polymer having carboxyl, hydroxyl or amide groups, a weight average molecular weight of about 2500-25,000 and a glass transition temperature of about -20C to +25C.
Typically useful acrylic polymers contain alkyl methacrylate, alkyl acrylate, hydroxyalkyl acrylate, hydroxyalkyl methacylate and can contain styrene, acrylic acid or methacrylic acid. Amide monomers such as methyacrylamide and acrylamide can be used; glycidyl monomers such as glycidyl acrylate or glycidyl methacrylate can also be used.
9~
Preferred acrylic po]ymers are of an alkyl methacrylate that has 1-18 carbon atoms in the alkyl 9L'OUp, an alkyl acrylate that has 1-18 carbon atoms in the alkyl group and a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl group. To form an acrylic polymer which has a hydroxyl content of about 2-6% by weight, a sufficient amount of the aforementioned hydroxyalkyl acrylate or methacrylate is utilized. The polymer also can contain small amounts of ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, itaconic acid, in amounts of about 0.1-5% by weight.
Typical alkyl methacrylates and acrylates that can be used to prepare the acrylic polymers are: methyl methyacrylate, ethyl methacrylatel butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, propyl methacrylate, phenyl methaerylate, isobornyl methacry-late, methyl aerylate, ethyl aerylate, propyl aerylate,isopropyl aerylate, butyl aerylate, isobutyl aerylate, hexyl aerylate, 2-ethylhexyl aerylate, nonyl aerylate, lauryl aerylate, stearyl acrylate, eyelohexyl aerylate, isodecyl aerylate, phenyl aerylate~ isobornyl aerylate, and the like.
Adhesion promoting monomers ean also be used in the aerylie polymers sueh as diethyl aminoethyl methaerylate, tertiary butyl aminoethyl methaerylate,
3-(2-methaeryloxy ethyl)-2,2-spiro eyelohexyl oxazolidene and the like.
Typical hydroxyalkyl aerylates and methaery-lates which can be used to prepare the acrylic polymers 7~P~
are: 2-hydroxyethyl acrylate, hydroxypropyl acrylate,
Typical hydroxyalkyl aerylates and methaery-lates which can be used to prepare the acrylic polymers 7~P~
are: 2-hydroxyethyl acrylate, hydroxypropyl acrylate,
4-hydroxybutyl acrylate, 2-hydroxyethyl methacylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, and the like.
The acrylic polymers can contain about 0Ol-30%
by weight of other constituents such as acrylonitrile, methacrylonitrile, acrylamide and methacrylamide, styrene or substituted styrene such as methyl styrene.
The acrylic polymers utilized in the coating composition are prepared by solution polymerization in which the monomers are blended with solvent, polymerization initiator and, optionally, a chain transfer agent, and heated to about 75-lOSC for 1-6 hours to form a polymer that preferably has a weight average molecular weight of about 2500-25,000, a hydroxyl content of 2-6~ by weight and a glass transition temperature of about -20C to +25C.
The weight average molecular weight of the acrylic polymers is determined by gel permeation chroma-tography using polymethylmethacrylate or polystyrene as a standard.
The glass transition temperature of the poly-mers is determined by differential scanning calorimetry or is calculated.
One technique that is successfully used in preparing the acrylic polymers is a pro~rammed addition of monomers, solvents, initiator solution and optionally a chain transfer agent into a polymerization vessel at a given rate. Optionally, the polymers can be terminated with the chain transfer agent at the desired low molecular weight. Also, if required, after the poly-merization is completed, solvents can be stripped off -to increase the polymer solids content of the resulting polymer solution.
~2~279~
Typical solvents which are used to prepare the acrylic polymer are the following: toluene, n-butyl acetate, methyl ethyl ketone/ methyl n-amyl ketone, n-butyl alcohol/ ethylene glycol monoethyl ether acetate, and other aliphatic, cyloaliphatic and aromatic hydro-carbons, esters, ethers, ketones and alcohols.
About 0.1-4% by weight, based on the weiqht of the monomers, of the polymerization initiator is used to prepare the acrylic polymer. Typlcal initiators are:
azobisisobut~ronitrile, azobis(gamma-dimethyl valeronitrile), benzoyl peroxide, t-butyl peracetate, di-ti-butyl peroxide and the like.
A chain transfer agent can be used to control the molecular weight of the acrylic polymer. Typical chain transfer agents are 2--mercaptoethanol, dodecyl mercaptan, benzene thioethanol, mercaptosuccinic acid, butyl mercaptan, mercaptopropionic acid and the like.
When a transfer agent is used, the resulting acrylic polymer contains about 0.1-10% by weight of the chain transfer agent.
Useful acrylic polymers for the preferred composition contain 50-90% by weight of an alkyl methac-rylate or an alkyl acrylate each having 1-12 carbon atoms in the alkyl groups or a mixture thereof, and 10-50% by weight of a hydroxyalkyl acrylate or a hydroxy-alkyl methacrylate each having 2-4 carbon atoms in the alkyl group or a mixture thereof. These polymers can contain up to 30~ by weight of styrene which replaces a portion of the alkyl methacrylate or alkyl acrylate.
Also these polymers can contain up to 5% by weight of an ethylenically unsaturated carboxylic acid.
An alkylated melamine formaldehyde crosslink-ing agent is used in the composition. The alkylated ~a2~L27e~4 melami~e formaldehyde resin used generally has 1-4 car-bon atoms in the alkyl group. The resin is prepared by conventional techniques in which an alcohol such as methanol, ethanol, propanol, isopropanol, butanol, iso-butanol and the like is reacted with a melamine formalde-hyde resin. The resin can be fully alkylated and sub-stantially monomeric or partially alkylated and poly-meric. One preferred resin which gives a high quality finish is a fully alkylated methoxy/butoxymethyl mela-mine (Monsanto Resimene~ 755). Another useful resin isa low temperatur~ cure, high solids, partially methy-lated, polymeric melamine formaldehyde resin (~onsanto Resimene~ 717). When a fully alkylated melamine is used, the compo~itlon contains about 0.1-2.0% by weight, based on the weight of the binder, of a strong acid catalyst.
When a polymeric melamine is used, the main film-forming polymer contains about 2-5% of a carboxylic acid to catalyze the curing reaction.
The composition may contain hydroxy-terminated polyester urethanes to improve flow-out of the color coat and, consequently, smoothness of the clear applied over it. These polyurethanes can be incorporated for the additional purpose of increasing the flexibility of the color coat so that it can be applied to flexible substrates such as fascia materials under a flexible clear and will withstand bending of the coated fascia material at low temperatures without cracking. The composition may contain up to 40% by weight, based on the total binder, of polyurethane which replaces a por-tion of the acrylic resin. One polyurethane used inthese compositions is prepared by reacting 75 parts by weight of polycaprolactonediol ha~ing a number average molecular weight of 830 and 2 parts by weight of 2,2-bis(hydroxymethyl) propionic acid with 30 parts by 7~
weight of methylenebis(cyclohexylisocyanate) in xylene/
ethyl acetate solution and has a number average molecular weight of about 7,000 as determined by gel permeation chromatography using polymethyl methacrylate as standard.
Also, in addition to the above constituents, plasticlzers in the amount of 0.1-10% by weight, based on the weight of ~he binder, can be used in the composi tion. Plasticizers that can be used are, for example, butyl benzyl phthalate, dibutyl phthalate, triphenyl phosphate, 2-ethylhexyl benzyl phthalate, dicyclohexyl phthalatel diallyl phthalate, dibenzyl phthalate, fatty acid esters of pentaerythritol, poly-(propylene adipate) dibenzoate, diethylene glycol dibenzoate, tetrabutyl~
thiodisuccinate, butylphthalylbutyl glycolate, acetyl-tributyl citrate, dibenzyl sebacate, tricresyl phos-phate, toluene N-ethyl sulfonamide, and di-2-ethylhexyl phthalate.
An acid catalyst solution can be added to the composition to increase the rate of crosslinking of the composition on curing. Generally, about 0.1-2% by weight, based on the weight of the binder, of acid catalyst is used. For example, phosphoric acid or an alkyl acid phosphate in which the alkyl group has 1-12 carbon atoms can be utilized for this purpose. Typical alkyl acid phosphates are methyl acid phosphate, ethyl acid phosphate, octyl acid phosphate, phenyl acid phos-phate, and the like. An alkyl sulfonic acid or an aryl sulfonic acid can be used such a methane sulfonic acid, para-toluene sulfonic acid or dodecylbenzene sulfonic acid.
To prevent viscosity increase and gelation "in the can" of the compositions containing a strong ~Z~Z7~
acid catalyst, the acid catalyst must be fully neutralized with an amine which will volatilize or decompose at the baking temperature of the coating.
Examples of such amines are n-propylamine and alkyl oxazolidines. A preferred neutralizing amine is 4,4-dimethyloxazolidine.
The color coat composition contains pigments in a pigment-to-binder ratio of about 2/100 to 150/100.
These pigments can be introduced into the composition by first forming a mill base with the acrylic polymer utilized in the composition or with other compatible polymers or polymeric dispersants by conventional techni~ues, such as sand grinding, ball milling, attritor grinding, two roll milling to disperse the pigments. The mill base is blended with the film-forming constituents as shown in the following Examples.
Any of the conventional pigments used in the coating compositions can be utilized in this composition such as the following: metallic oxides, such as titanium dioxide, zinc oxide, iron oxide and the like, metal hydroxides, metal flakes such as aluminum flake, chromates, such as lead chromate, sulfides, sulfates, carbonates, carbon black, silica, talc, china clay, phthalocyanine blues and greens, organo reds, organo maroons and other organic dyes, organic pigments and lakes.
The volatile organic solvent carrier in which the high solids color coat enamel composition of the invention is dissolved should contain at least one fast evaporating, strong solvent for AS~ such as methanol, ethanol, acetone and methyl ethyl ketone in order to maximize the spray solids at spray viscosity. A combi-nation of methanol with one or both of ethanol and methyl ethyl ketone ranging from about 30% to about 60~
by weight o~ the total solvents present in the enamel at ~%~ ;J94 spray viscosity is generally used. The color coat enamel should also contain at least one slower evapor-ating poor solvent or solvent mixture for ASB in order to allow the ASB to set up the color coat as soon as the volatile, strong ASB solvents have evaporated. Examples of such poor solvents are methyl n-amyl ketone, n-butyl acetate, ethylene glycol monobutyl ether acetate, and an approximately equivolume blend of ethylene glycol mono-ethyl ether acetate with diisobutyl ketone. The color coat enamel may also contain minor amounts, up to 20% of total solvents, of a medium evaporating, good ASB sol-vent to promote flow-out of the color coat and smooth-ness of the color coat/clear coat finish. Examples of such solvents are ethylene glycol monomethyl ether and propylene glycol monomethyl ether. The color coat enamel should contain a minimum of and preferably no slow evaporating, good solvents for ASB which would prevent the ASB from setting up the color coat by forming a relatively low viscosity solution of it.
Examples of such undesirable solvents are diacetone alcohol, ethylene glycol monobutyl ether and diethylene glycol monoethyl ether. Minor amounts of non-solvents for ASB, such as aromatic and aliphatic hydrocarbons, may be incorporated in the color coat enamel without interfering with the desired rheological effect of the ASB.
Any suitable clear coat composition can be applied over the color coat enamel of this invention pro-vided it contains no substantial amount of slower evapo-rating, strong ASB solvents which can stri~e into thecolor coat and provided it adheres firmly to the color coat layer after cure. To obtain good outdoor durabili-ty, clear coat enamels based on acrylic/melamine binders are preferred for use over rigid substrates like steel and rigid plastics. Over flexible substrates like RIM, .;~, ~2~ 4 the clear binder may comprise a hydroxy-terminated poly-ester urethane resin in combination with a hydroxy-functional acrylic ~r polyester resin and a melamine crosslinker.
Optionally, the color coat can contain about 0.1-10% by weight, based on the weight of the binder of the color coat, of an ultraviolet light absorber.
Another option is that the color coat and the clear coat each can contain about 0.1-10% by weight, based on the weight of the binder of the coat, of an ultraviolet light absorber. Also, the color coat or the clear coat can contain about 0~1-5% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
When a hindered amine light stabilizer is used, the ratio of ultraviole~ light absorber to hindered amine light stabilizer is about 1:1 to about 5:1.
Preferred, to lorm a durable finish, the color coat contains about 1-2~ by weight of an ultraviolet light absorber and about 1% of a hindered amine light stabilizer and the clear coat contains about 2-5% of an ultraviolet light absorber and about 1% of a hindered amine light stabilizer.
The coating compositions of this invention can be applied over a variety of substrates, such as metal;
wood, glass, plastics, and the like, by any suitable spray application method, such as conventional spraying, electrostatic spraying, or spraying from electrostatic high speed rotary atomizers, e.g., turbobells, and the like. The viscosity of the composi~ions can be adjusted for any of these methods by adding solvents if necessary.
Generally, the composition is utilized at a high solids content which keeps air pollution at a minimum.
~2'79~
The clear coat is usually applied to the wet color coat after a solvent flash period of 1 5 minutes, but the color coat may be dried or cured partially or completely by baking before applying the clear. One technique that is used to insure that there will be no popping or cratering of the coating is to allow the sol~ents to flash off for about 1-5 minutes before a second coating ~s sprayed on or otherwise applied, then waiting for about 2-10 minutes before baking the coating to allow additional solvents to flash off.
The color coat/clear coat coatings are baked at relatively low temperatures of about 70-150C for about 15 minutes to 2 hours. The resulting coating is about 1-5 mils thick but for most uses a 2-3 mil thick ~5 coating is used. Generally, the color coat is about 0.4-1.6 mils thick and preferably 0.6-1.4 mils thick, and the clear coat is about 0.6-4.0 mils thick and preferably 1.5-2.0 mils thick.
The resulting coating has good gloss, appear-ance and adhesion to substrates of all types. Thesecharacteristics make the compositior. particularly use-ful as a finish for automobiles, trucks and other out-door equipment.
The following examples illustrate the inven-tion. All parts, percentages and ratios are on a weight~asis unless otherwise indicated. Molecular weights are determined by gel permeation chromatography.
EXAMP~E 1 An acrylic polymer solution was prepared as follows. A 5 liter round bottom flask equipped with a thermometer, stirrer, reflux condenser, two addition funnels, and a heating mantle was charged with 960 grams of methyl n-amyl ketone. The following premixed solu-tions were charged to the addition funnels:
2~4 Grams Monomer ~ixture Methyl methacrylate 600 Butyl acrylate 800 2-~ydroxyethyl acrylate 600 Total 2000 Initiator Solution Methyl n-amyl ketone 120 t-Butyl peracetate (75% solids in mineral spirits) 80 Total 200 The flask charge was heated to reflux. Addl-tion of the monomer mixture and initiator solution was then started simultaneously. The monomer mixture was added linearly over 240 minutes and the initiator solu-tion was added linearly over 260 minutes. The reaction mixture was maintained at reflux during the addition period and for an additional 30 minutes after addition of the initiator solution was complete. The resulting polymer solution was cooled. It had a solids content of 64.0~.
The polymer was a methyl methacrylate~butyl ac~ylate/2-hydroxyethyl acrylate copolymer in a weight ratio of 30/40/30. The polymer had a weight average molecular weight (Mw) of 5300 and nad a calculated glass transition temperature (Tg) of -9C.
The following aluminum flake mill base was prepared:
Grams Non-leafing, acid spot resistant, medium particle size aluminum flake paste (64% solids in mineral spirits) 293.0 Methyl n-amyl ketone 105~5 Acrylic polymer solution (prepared abo~-e) 351.5 :~L2~
The above ingredients we~e vi~orously stirr2d together for 2 hours to form a homog~neous dispersion of the aluminum flake~O The mill base contained 25~ o~
pigment and 30% of acrylic p~lymer.
The following light bl~le meta].lic color coat enamels were prepared:
Grams Color Coat A Color Coat B
Ingredients Containing ASB Without ASB
Portion 1 Acrylic polymer solution (prepared above) 196.3 154.7 Polyurethane solution consisting of 62.5% of hydroxy-terminated poly-ester urethane (condensation product of 75.16 parts of poly-caprolactonediol of number average molecular weight of 830, 1.94 parts of 2,2-bis(hydroxymethyl)propionic acid and 22.90 parts of methylene-bis(cyclohexylisocyanate) having a number average molecular weight of about 7,000),24.2% of xylene and 13.3% of ethyl acetate 144.0 76.8 Indanthrone blue mill base consisting of 12.0% of indanthrone blue pigment, 48.0% of a styrene/methyl methacry-late/butyl acrylate/2-hydroxyethyl acrylate (15/15/40/30 weight ratio) copolymer having a ~w of about 6,000, and 40.0% of methyl n-amyl ketone and prepared by grinding in a Schold mill 60.5 32.2 Phthalocyanine blue mill base consist-ing of 18.2% of copper phthalocyanine blue pigment, 21.5% of the copolymer present in the above mill base, 2.8%
of an A-B dispersant (methyl methacry-late/butyl methacrylate 50/50 weight ratio copolymer terminated with the mercaptoethanol and reacted with the biuret of hexamethylenediisocyanate and capped with ammonia), 55.3% of methyl n-amyl ketone and 2.2% of toluene and prepared by grinding in a steel mill with diagonal steel media 8.6 4.6 27~4 Black mill base consisting of 11.7%
of high color furnace type carbon black pigment, 11~7% of the copoly-mer present in the above mill base, 11.7% of the A-B dispersant present in the above mill base, 55O4% of methyl n-amyl ketone and 9.5% of toluene and prepared by grinding in a steel mill with diagonal steel media 2.0 1.1 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~ 328) in xylene (30%
solids) 20.0 10.7 Hindered amine light stabilizer (Tinuvin~ 079) solution in xylene (40% solids) 15.0 3.0 Portion 2 Aluminum flake mill base (prepared above) 275.8147.1 Portion 3 Methyoxy/butoxymethyl melamine (Resimene~755) 210.0112.0 ASB solution consisting of 30% of alcohol soluble cellulose acetate butyrate (Eastman CAB-533-0.4) hav-ing a viscosity of 0~25 second, 35% of toluene-denatured anhydrous ethyl alcohol, and 35% of methyl n-amyl ketone 200.0 Toluene denatured anhydrous ethyl alcohol 70.2 64.3 Portion 4 Catalyst solution consisting of 28.57%
a Cycat~ 600 dodecylbenzenesulfonic acid solution in isopropanol (70%
solids, 12.76% of Amine CS-1135 4,4 dimethyloxazolidine solution in water (78% active), and 58.67% of methanol 24.0 12.8 Methanol 44.1 23.5 Portion 5 Thinner consisting of 25% of toluene-denatured anhydrous ethyl alcohol, 25% of butyl acetate, 25% of propy-lene glycol monomethyl ether and 25% of methyl n-amyl ketone 520.099.3 ~2~271~4 Portion 1 was charged to a mixing vesse], and thoroughly blended. Portion 2 was added and stirred in for 30 minutes. Portions 3 and 4 were then added in turn and each stirred in for 30 minutes. Finally, the color coat enamels were reduced to a spray viscosity of 22 seconds in a No. 2 Fisher viscosity cut with Portion
The acrylic polymers can contain about 0Ol-30%
by weight of other constituents such as acrylonitrile, methacrylonitrile, acrylamide and methacrylamide, styrene or substituted styrene such as methyl styrene.
The acrylic polymers utilized in the coating composition are prepared by solution polymerization in which the monomers are blended with solvent, polymerization initiator and, optionally, a chain transfer agent, and heated to about 75-lOSC for 1-6 hours to form a polymer that preferably has a weight average molecular weight of about 2500-25,000, a hydroxyl content of 2-6~ by weight and a glass transition temperature of about -20C to +25C.
The weight average molecular weight of the acrylic polymers is determined by gel permeation chroma-tography using polymethylmethacrylate or polystyrene as a standard.
The glass transition temperature of the poly-mers is determined by differential scanning calorimetry or is calculated.
One technique that is successfully used in preparing the acrylic polymers is a pro~rammed addition of monomers, solvents, initiator solution and optionally a chain transfer agent into a polymerization vessel at a given rate. Optionally, the polymers can be terminated with the chain transfer agent at the desired low molecular weight. Also, if required, after the poly-merization is completed, solvents can be stripped off -to increase the polymer solids content of the resulting polymer solution.
~2~279~
Typical solvents which are used to prepare the acrylic polymer are the following: toluene, n-butyl acetate, methyl ethyl ketone/ methyl n-amyl ketone, n-butyl alcohol/ ethylene glycol monoethyl ether acetate, and other aliphatic, cyloaliphatic and aromatic hydro-carbons, esters, ethers, ketones and alcohols.
About 0.1-4% by weight, based on the weiqht of the monomers, of the polymerization initiator is used to prepare the acrylic polymer. Typlcal initiators are:
azobisisobut~ronitrile, azobis(gamma-dimethyl valeronitrile), benzoyl peroxide, t-butyl peracetate, di-ti-butyl peroxide and the like.
A chain transfer agent can be used to control the molecular weight of the acrylic polymer. Typical chain transfer agents are 2--mercaptoethanol, dodecyl mercaptan, benzene thioethanol, mercaptosuccinic acid, butyl mercaptan, mercaptopropionic acid and the like.
When a transfer agent is used, the resulting acrylic polymer contains about 0.1-10% by weight of the chain transfer agent.
Useful acrylic polymers for the preferred composition contain 50-90% by weight of an alkyl methac-rylate or an alkyl acrylate each having 1-12 carbon atoms in the alkyl groups or a mixture thereof, and 10-50% by weight of a hydroxyalkyl acrylate or a hydroxy-alkyl methacrylate each having 2-4 carbon atoms in the alkyl group or a mixture thereof. These polymers can contain up to 30~ by weight of styrene which replaces a portion of the alkyl methacrylate or alkyl acrylate.
Also these polymers can contain up to 5% by weight of an ethylenically unsaturated carboxylic acid.
An alkylated melamine formaldehyde crosslink-ing agent is used in the composition. The alkylated ~a2~L27e~4 melami~e formaldehyde resin used generally has 1-4 car-bon atoms in the alkyl group. The resin is prepared by conventional techniques in which an alcohol such as methanol, ethanol, propanol, isopropanol, butanol, iso-butanol and the like is reacted with a melamine formalde-hyde resin. The resin can be fully alkylated and sub-stantially monomeric or partially alkylated and poly-meric. One preferred resin which gives a high quality finish is a fully alkylated methoxy/butoxymethyl mela-mine (Monsanto Resimene~ 755). Another useful resin isa low temperatur~ cure, high solids, partially methy-lated, polymeric melamine formaldehyde resin (~onsanto Resimene~ 717). When a fully alkylated melamine is used, the compo~itlon contains about 0.1-2.0% by weight, based on the weight of the binder, of a strong acid catalyst.
When a polymeric melamine is used, the main film-forming polymer contains about 2-5% of a carboxylic acid to catalyze the curing reaction.
The composition may contain hydroxy-terminated polyester urethanes to improve flow-out of the color coat and, consequently, smoothness of the clear applied over it. These polyurethanes can be incorporated for the additional purpose of increasing the flexibility of the color coat so that it can be applied to flexible substrates such as fascia materials under a flexible clear and will withstand bending of the coated fascia material at low temperatures without cracking. The composition may contain up to 40% by weight, based on the total binder, of polyurethane which replaces a por-tion of the acrylic resin. One polyurethane used inthese compositions is prepared by reacting 75 parts by weight of polycaprolactonediol ha~ing a number average molecular weight of 830 and 2 parts by weight of 2,2-bis(hydroxymethyl) propionic acid with 30 parts by 7~
weight of methylenebis(cyclohexylisocyanate) in xylene/
ethyl acetate solution and has a number average molecular weight of about 7,000 as determined by gel permeation chromatography using polymethyl methacrylate as standard.
Also, in addition to the above constituents, plasticlzers in the amount of 0.1-10% by weight, based on the weight of ~he binder, can be used in the composi tion. Plasticizers that can be used are, for example, butyl benzyl phthalate, dibutyl phthalate, triphenyl phosphate, 2-ethylhexyl benzyl phthalate, dicyclohexyl phthalatel diallyl phthalate, dibenzyl phthalate, fatty acid esters of pentaerythritol, poly-(propylene adipate) dibenzoate, diethylene glycol dibenzoate, tetrabutyl~
thiodisuccinate, butylphthalylbutyl glycolate, acetyl-tributyl citrate, dibenzyl sebacate, tricresyl phos-phate, toluene N-ethyl sulfonamide, and di-2-ethylhexyl phthalate.
An acid catalyst solution can be added to the composition to increase the rate of crosslinking of the composition on curing. Generally, about 0.1-2% by weight, based on the weight of the binder, of acid catalyst is used. For example, phosphoric acid or an alkyl acid phosphate in which the alkyl group has 1-12 carbon atoms can be utilized for this purpose. Typical alkyl acid phosphates are methyl acid phosphate, ethyl acid phosphate, octyl acid phosphate, phenyl acid phos-phate, and the like. An alkyl sulfonic acid or an aryl sulfonic acid can be used such a methane sulfonic acid, para-toluene sulfonic acid or dodecylbenzene sulfonic acid.
To prevent viscosity increase and gelation "in the can" of the compositions containing a strong ~Z~Z7~
acid catalyst, the acid catalyst must be fully neutralized with an amine which will volatilize or decompose at the baking temperature of the coating.
Examples of such amines are n-propylamine and alkyl oxazolidines. A preferred neutralizing amine is 4,4-dimethyloxazolidine.
The color coat composition contains pigments in a pigment-to-binder ratio of about 2/100 to 150/100.
These pigments can be introduced into the composition by first forming a mill base with the acrylic polymer utilized in the composition or with other compatible polymers or polymeric dispersants by conventional techni~ues, such as sand grinding, ball milling, attritor grinding, two roll milling to disperse the pigments. The mill base is blended with the film-forming constituents as shown in the following Examples.
Any of the conventional pigments used in the coating compositions can be utilized in this composition such as the following: metallic oxides, such as titanium dioxide, zinc oxide, iron oxide and the like, metal hydroxides, metal flakes such as aluminum flake, chromates, such as lead chromate, sulfides, sulfates, carbonates, carbon black, silica, talc, china clay, phthalocyanine blues and greens, organo reds, organo maroons and other organic dyes, organic pigments and lakes.
The volatile organic solvent carrier in which the high solids color coat enamel composition of the invention is dissolved should contain at least one fast evaporating, strong solvent for AS~ such as methanol, ethanol, acetone and methyl ethyl ketone in order to maximize the spray solids at spray viscosity. A combi-nation of methanol with one or both of ethanol and methyl ethyl ketone ranging from about 30% to about 60~
by weight o~ the total solvents present in the enamel at ~%~ ;J94 spray viscosity is generally used. The color coat enamel should also contain at least one slower evapor-ating poor solvent or solvent mixture for ASB in order to allow the ASB to set up the color coat as soon as the volatile, strong ASB solvents have evaporated. Examples of such poor solvents are methyl n-amyl ketone, n-butyl acetate, ethylene glycol monobutyl ether acetate, and an approximately equivolume blend of ethylene glycol mono-ethyl ether acetate with diisobutyl ketone. The color coat enamel may also contain minor amounts, up to 20% of total solvents, of a medium evaporating, good ASB sol-vent to promote flow-out of the color coat and smooth-ness of the color coat/clear coat finish. Examples of such solvents are ethylene glycol monomethyl ether and propylene glycol monomethyl ether. The color coat enamel should contain a minimum of and preferably no slow evaporating, good solvents for ASB which would prevent the ASB from setting up the color coat by forming a relatively low viscosity solution of it.
Examples of such undesirable solvents are diacetone alcohol, ethylene glycol monobutyl ether and diethylene glycol monoethyl ether. Minor amounts of non-solvents for ASB, such as aromatic and aliphatic hydrocarbons, may be incorporated in the color coat enamel without interfering with the desired rheological effect of the ASB.
Any suitable clear coat composition can be applied over the color coat enamel of this invention pro-vided it contains no substantial amount of slower evapo-rating, strong ASB solvents which can stri~e into thecolor coat and provided it adheres firmly to the color coat layer after cure. To obtain good outdoor durabili-ty, clear coat enamels based on acrylic/melamine binders are preferred for use over rigid substrates like steel and rigid plastics. Over flexible substrates like RIM, .;~, ~2~ 4 the clear binder may comprise a hydroxy-terminated poly-ester urethane resin in combination with a hydroxy-functional acrylic ~r polyester resin and a melamine crosslinker.
Optionally, the color coat can contain about 0.1-10% by weight, based on the weight of the binder of the color coat, of an ultraviolet light absorber.
Another option is that the color coat and the clear coat each can contain about 0.1-10% by weight, based on the weight of the binder of the coat, of an ultraviolet light absorber. Also, the color coat or the clear coat can contain about 0~1-5% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
When a hindered amine light stabilizer is used, the ratio of ultraviole~ light absorber to hindered amine light stabilizer is about 1:1 to about 5:1.
Preferred, to lorm a durable finish, the color coat contains about 1-2~ by weight of an ultraviolet light absorber and about 1% of a hindered amine light stabilizer and the clear coat contains about 2-5% of an ultraviolet light absorber and about 1% of a hindered amine light stabilizer.
The coating compositions of this invention can be applied over a variety of substrates, such as metal;
wood, glass, plastics, and the like, by any suitable spray application method, such as conventional spraying, electrostatic spraying, or spraying from electrostatic high speed rotary atomizers, e.g., turbobells, and the like. The viscosity of the composi~ions can be adjusted for any of these methods by adding solvents if necessary.
Generally, the composition is utilized at a high solids content which keeps air pollution at a minimum.
~2'79~
The clear coat is usually applied to the wet color coat after a solvent flash period of 1 5 minutes, but the color coat may be dried or cured partially or completely by baking before applying the clear. One technique that is used to insure that there will be no popping or cratering of the coating is to allow the sol~ents to flash off for about 1-5 minutes before a second coating ~s sprayed on or otherwise applied, then waiting for about 2-10 minutes before baking the coating to allow additional solvents to flash off.
The color coat/clear coat coatings are baked at relatively low temperatures of about 70-150C for about 15 minutes to 2 hours. The resulting coating is about 1-5 mils thick but for most uses a 2-3 mil thick ~5 coating is used. Generally, the color coat is about 0.4-1.6 mils thick and preferably 0.6-1.4 mils thick, and the clear coat is about 0.6-4.0 mils thick and preferably 1.5-2.0 mils thick.
The resulting coating has good gloss, appear-ance and adhesion to substrates of all types. Thesecharacteristics make the compositior. particularly use-ful as a finish for automobiles, trucks and other out-door equipment.
The following examples illustrate the inven-tion. All parts, percentages and ratios are on a weight~asis unless otherwise indicated. Molecular weights are determined by gel permeation chromatography.
EXAMP~E 1 An acrylic polymer solution was prepared as follows. A 5 liter round bottom flask equipped with a thermometer, stirrer, reflux condenser, two addition funnels, and a heating mantle was charged with 960 grams of methyl n-amyl ketone. The following premixed solu-tions were charged to the addition funnels:
2~4 Grams Monomer ~ixture Methyl methacrylate 600 Butyl acrylate 800 2-~ydroxyethyl acrylate 600 Total 2000 Initiator Solution Methyl n-amyl ketone 120 t-Butyl peracetate (75% solids in mineral spirits) 80 Total 200 The flask charge was heated to reflux. Addl-tion of the monomer mixture and initiator solution was then started simultaneously. The monomer mixture was added linearly over 240 minutes and the initiator solu-tion was added linearly over 260 minutes. The reaction mixture was maintained at reflux during the addition period and for an additional 30 minutes after addition of the initiator solution was complete. The resulting polymer solution was cooled. It had a solids content of 64.0~.
The polymer was a methyl methacrylate~butyl ac~ylate/2-hydroxyethyl acrylate copolymer in a weight ratio of 30/40/30. The polymer had a weight average molecular weight (Mw) of 5300 and nad a calculated glass transition temperature (Tg) of -9C.
The following aluminum flake mill base was prepared:
Grams Non-leafing, acid spot resistant, medium particle size aluminum flake paste (64% solids in mineral spirits) 293.0 Methyl n-amyl ketone 105~5 Acrylic polymer solution (prepared abo~-e) 351.5 :~L2~
The above ingredients we~e vi~orously stirr2d together for 2 hours to form a homog~neous dispersion of the aluminum flake~O The mill base contained 25~ o~
pigment and 30% of acrylic p~lymer.
The following light bl~le meta].lic color coat enamels were prepared:
Grams Color Coat A Color Coat B
Ingredients Containing ASB Without ASB
Portion 1 Acrylic polymer solution (prepared above) 196.3 154.7 Polyurethane solution consisting of 62.5% of hydroxy-terminated poly-ester urethane (condensation product of 75.16 parts of poly-caprolactonediol of number average molecular weight of 830, 1.94 parts of 2,2-bis(hydroxymethyl)propionic acid and 22.90 parts of methylene-bis(cyclohexylisocyanate) having a number average molecular weight of about 7,000),24.2% of xylene and 13.3% of ethyl acetate 144.0 76.8 Indanthrone blue mill base consisting of 12.0% of indanthrone blue pigment, 48.0% of a styrene/methyl methacry-late/butyl acrylate/2-hydroxyethyl acrylate (15/15/40/30 weight ratio) copolymer having a ~w of about 6,000, and 40.0% of methyl n-amyl ketone and prepared by grinding in a Schold mill 60.5 32.2 Phthalocyanine blue mill base consist-ing of 18.2% of copper phthalocyanine blue pigment, 21.5% of the copolymer present in the above mill base, 2.8%
of an A-B dispersant (methyl methacry-late/butyl methacrylate 50/50 weight ratio copolymer terminated with the mercaptoethanol and reacted with the biuret of hexamethylenediisocyanate and capped with ammonia), 55.3% of methyl n-amyl ketone and 2.2% of toluene and prepared by grinding in a steel mill with diagonal steel media 8.6 4.6 27~4 Black mill base consisting of 11.7%
of high color furnace type carbon black pigment, 11~7% of the copoly-mer present in the above mill base, 11.7% of the A-B dispersant present in the above mill base, 55O4% of methyl n-amyl ketone and 9.5% of toluene and prepared by grinding in a steel mill with diagonal steel media 2.0 1.1 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~ 328) in xylene (30%
solids) 20.0 10.7 Hindered amine light stabilizer (Tinuvin~ 079) solution in xylene (40% solids) 15.0 3.0 Portion 2 Aluminum flake mill base (prepared above) 275.8147.1 Portion 3 Methyoxy/butoxymethyl melamine (Resimene~755) 210.0112.0 ASB solution consisting of 30% of alcohol soluble cellulose acetate butyrate (Eastman CAB-533-0.4) hav-ing a viscosity of 0~25 second, 35% of toluene-denatured anhydrous ethyl alcohol, and 35% of methyl n-amyl ketone 200.0 Toluene denatured anhydrous ethyl alcohol 70.2 64.3 Portion 4 Catalyst solution consisting of 28.57%
a Cycat~ 600 dodecylbenzenesulfonic acid solution in isopropanol (70%
solids, 12.76% of Amine CS-1135 4,4 dimethyloxazolidine solution in water (78% active), and 58.67% of methanol 24.0 12.8 Methanol 44.1 23.5 Portion 5 Thinner consisting of 25% of toluene-denatured anhydrous ethyl alcohol, 25% of butyl acetate, 25% of propy-lene glycol monomethyl ether and 25% of methyl n-amyl ketone 520.099.3 ~2~271~4 Portion 1 was charged to a mixing vesse], and thoroughly blended. Portion 2 was added and stirred in for 30 minutes. Portions 3 and 4 were then added in turn and each stirred in for 30 minutes. Finally, the color coat enamels were reduced to a spray viscosity of 22 seconds in a No. 2 Fisher viscosity cut with Portion
5 and filtered through a fine paint strainer.
Following are compositional data on the re-sulting color coat enamels:
10 Color Coat A Color ~oat B
Acrylic polymer/polyurethane/ 38~9/],4.6/ 48.6/14.6/
melamine formaldehyde resin/ 34.0/9.7/ 34.0/0/0.8/
ASB/dodecylbenzene sul~onic 0.8/1.0/1.0 I.0/1.0 acid/ultraviolet light absorber/hindered amine light stabiliæer binder ratio Pigment/binder ratio 12.6/100 12.6/100 Calculated solids content 38~8~ 49.6%
The following high solids clear coat enamel was Prepared:
Grams Portion 1 Acrylic polymer solution of a styrene/
methyl methacrylate/butyl acrylate/
2-hydroxyethyl acrylate (15/36/32/
17 weight ratio) copolymer having a ~w of 15,000 (65.1% solid in methyl n-amyl ketone) 1997.0 Methoxy/butoxymethyl melamine 588.8 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids) 200.0 Hindered amine light stabilizer (Tinuvin~
079) solution in xyler,e (40~ solids) 50.0 Silicone solution of an orqanofunctional silicone (Baysilone~ Fluid OL) in xylene (10% solids) 1.7 ~ ,, ~Z~IZ~94 Portion 2 Silica mill base consisting of 8~93%
of a hydrophobic fumed silica (Aerosil~ R-972), 49.60% of methoxy/
buto~ymethyl melamine (Resimene~ 755) and 41.47% of xylene and prepared by sancl grinding 224.0 Portion 3 -Catalyst solution (described under Portion 4 of above color coat compo-sitions) 80.0 10 Methanol 84.8 Portion 4 -Silica bridging agent solution of poly-~inyl pyrrolidone of weight average molecular weight of about 40,000 ~PVP-K-30) in methanol (10% solids) 5.0 Portion 5 Aromatic hydrocarbon solvent boiling at 150-190C (Aromatic 100)782.3 Portion 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and stirred in for 10 minutes each. Portion 4 was added and stirred in for 30 minutes. Finally, the clear coat enamel was reduced to a spray viscosity of 45 seconds in a No. 2 Fisher cup with Portion 5 and filtered through a milk filter.
The resulting clear coat enamel has an acrylic polymer/melamine formaldehyde resin/dodecylbenzene sulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 62.0/33.3/0.8/2.9/1.0, a silica/binder ratio of 1.0/100 and a calculated solids content of 52.7%.
Each of the color coat enamels in combination with the clear coat enamel was sprayed onto 20 gauge phosphatized steel panels primed first with an electro-deposition primer and then with a high solids polyester/
melamine type primer-surfacer. The color coat enamel ~L21Zl~9~
and the clear coat enamel were applied from separate De ~ilbiss Model J~,A-502*pressure feed spray guns each equipped with an FX fluid tip having an orIfice of 0,0425 inch and with a No. 797 air cap. The color coat 5 and clear coat enamels were delivered to the spray guns from separate pressure tanks at controlled flow rates.
The atomizing air pressure was 70 psi at the base of the color coat gun and 60 psi at the base of the clear coat gun.
The color coat/clear coat coating compositions were applied by means of a Spraymation~ automatic panel spray machine. The color coat and clear coat spray guns were mounted side-by-side on a reciprocation arm travel-ling horizontally at a speed of about 764 inches/minute.
The panels were mounted vertically at a distance of 13 inches from the tips of the spray guns on a panel rack which moved vertically from a low to a high position in six 4-inch increments between passes of the spray gun across the pa~els to "index" the panels during the appli-cation of each coat of paint. The color coat enamelwas applied in two coats with a 1 minute solvent flash period between coats. The panels were then dried on the rack for 2 minutes and the clear coat was applied in two coats with a 1 minute solvent flash period between coats. The panels were then dried in a horizontal posi-tion for about 8 minutes, prebaked 15 minutes at 82C
and baked 30 minutes at 131C.
The propexties of the two color coat/clear coat finishes are compared below. The "distinctness of image" was determined b~T means of a Hunter Lab Dori-Gon Meter D47-6~and is a measure of film smoothness, with higher values representing smoother films having a more mirror-like reflectance. The "head-on brightness" and *denotes trade mark ~27~1~
"metallic index" (also called "flake orier~tation index") were measured with a special goniophotometer called Object-Modulated Reflectometer~ ~OMR~ and described in Troy U.S. Patent 4,359,504 issued November 16, 1982.
The head-on brightness was the lightness calculated from the reflectance measured at an angle of 5 from the normal and was a measure of the metallic lightness of the coating when viewed head-on. The metallic index was explained in U.SO 4,359,504 and was a measure of the metallic glamour or degree of two-tone of the coating.
For a given color coat pigmentation higher values of both of these metallic appearance properties result from better Elake orientation and represent a more desirable appearance than lower values.
15 Color Coat A/ Color Coat B/
Clear Coat Clear Coat Properties Finish Finish Thickness, mils:
Color coat 0.77 0.74 Clear coat 1.8 1.8 20 Gloss measured at 20~ 93 76 Distinctness of image 82 42 Head-on brightness 110 69 Metallic index 60 32 Mottling Slight Definite 25 Tukon hardness, Knoop7.9 6.4 The color coat/clear coat finish prepared from color coat A containing ASB had greatly superior gloss, distinctness of image, head-on brightness, metal-lic index and freedom from mottling than the comparable finish prepared from color coat B con-aining no ASB.
Additional coatings were sprayed from the color coat A enamel with the clear coat enamel under the conditions described above at different col~r coat and clear coat film thicknesses and had the following properties:
~271~
2~
Thin Intermediate Thick Property Coatinq Coating _ Coating Thickness t mils:
Color coat 0.53 0.71 1.04 Clear coat 1.7 1.8 2.2 Gloss measured at 2Q93 95 94 Distinctness of image 81 84 84 Head-on brightness 111 112 113 Metallic index 60 61 61 10 Mottling None None None The above coatings prepared from color coat A
had consistent and excellent appearance properties o~er a wide range of color coat film thicknesses at least as great as that encountered in commercial application of this type of finish.
EX~MPLE 2 An acryllc polymer solution was prepared as follows. A 12 liter round bottom flas}; equipped with a thermometer, stirrer, distillation head with reflux condenser, two addition funnels, and a heating mantle was charged wlth 3093 grams of methyl n-amyl ketone.
The following premixed solutions were charged to the addition funnels:
Grams 25 Monomer Mi~ture Styrene 750 ~ethyl methacrylate 750 Butyl acrylate 2000 2-Hydroxyethyl acrylate 1500 Total 5000 Initiator Solution Methyl n-amyl ketone 333 t-Butyl peracetate (75~ solids in mineral spirits) 167 Total 500 2~
The flask charge was heated to reflux.
Addition of the monomer mixture and initiator solution was then started simultaneously. The monomer mix-ture was added linearly over 225 minutes and the initiator solution was added linearly over 240 minutes. The reaction mixture was maintained at reflux during the addition period and for an additional 30 minutes after addition of -the initiator solution was complete. About 1762 grams of volatiles, consisting principalLy of methyl n-amyl ketone, was then distilled off and the ~olution in the flask was cooled. The resul~in~ polymer solution has a solids content of about 75~, The polymer was a styrene/methyl methacrylate/-butyl acrylate/2-hydroxyethyl acrylate copolymer in a weight ratio of 15/15/40/30. The polymer had a Mw of about 6,000 and a calculated Tg of -9C.
The following aluminum flake mill base was prepared:
Grams Portion 1 Acrylic polymer solution ~prepared above) 2780 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30~ solids) 632 25 Hindered amine light stabilizer (Tinuvin~
079) solution in xylene (40% solids) 237 Portion 2 Non-leafinq, acid spot resistant, medium particle size aluminum flake paste (64% solids in mineral spirits) 1851 Portion 1 was charged to a mixing vessel and thoroughly blended. Portion 2 was added, and the mix-ture was stirred vigorously to form a homogeneous dis-persion of the aluminum flakes. The mill base contained 21.5490 of pigment, 37.9% of acrylic polymer, 3.45% of ultraviolet light absorber, and 1.72% of hindered light absorber.
,' 7'~4 The following dark blue metallic color coat enamel was prepared:
Grams Portion 1 ~lue mill base consisting of 12.0% of copper phthalocyanine blue pigment (green shade), 48.0% of the acrylic polymer prepared above and 40.0% of methyl n-amyl ketone and prepared by grinding in a Schold mill 284h.4 Black mill base (described under Por-tion 1 of Example 1 color coat compo-sitions) 373.8 White mill base consisting of 70.0% of rutile titanium dioxide pigment, 10.0%
of the acrylic polymer prepared above, and 20.0% of methyl n-amyl ketone and prepared by sand grinding 37.2 Aluminum flake mill base (~repared above) 179.7 Acrylic polymer solution (prepared above) 246.3 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30~ solids) 179.1 Hindered amine li~ht stabilizer (Tinuvin~
079) solution in xylene (40% solids) 67.5 Portion 2 -Methoxy/butoxymethyl melamine (Resimene~ 755) 1140.0 ASs solution (described under Portion 3 of Example 1 color coat compositions) 500.0 Toluene denatured anhydrous ethyl alcohol 550.2 Portion 3 Amine solution consisting of 25.64% of Amine CS-1135~ 4,4-dimethyyloxazolidine solution in water (78% active) and 74O36% of methanol 44.7 Catalyst solution consisting of 17.8% of p-toluenesulfonic acid, 12.5% of Amine CS-1135~, and 69.7% of methanol60.6 Methanol 198.0 ~ Z~ ~J~9 Portion 4 Thinner consisting of 25% of toluene-denatured anhydrous ethyl alcohol, 25%
of propylene qlycol monomethyl ether, and 50% of xylene 940.0 Portion 1 was charged to a mixing vessel and thoroughly blended. Portion 2 was added and stirred in for 15 minutes. Portion 3 was then added and stirred in for 30 minutes. The color coat enamel was reduced to a stray viscosity of 35 seconds in a No. 2 Fisher cut with Portion 5 and filtered through a fine paint strainer. The resulting color coat enamel had an acrylic polymer/melamine formaldehyde resin/~SB/p-toluenesulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 55.15/36.76/4.8~/
0.35/1.93/0.97, a pigment/binder ratio of 14.5/100 and a calculated solids content at 48.2%.
The following high solids clear coat enamel was prepared:
Grams POrtion 1 -Acrylic polymer solution (prepared above) 3200.0 Silica mill base (described in Portion 2 of Exam~le 1 clear coat composition) 896.0 Methoxy/butoxymethyl melamine (Resimene~ 755) 1155.5 Portion 2 Ultraviole~ light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids) 400.0 Hindered amine light stabilizer (Tinuvin~
079) solution in xylene (40% solids) 100.0 Silicone solution (1% solids in xylene of 100 centistroke silicone fluid) 60.0 Portion 3 Amine solution (described in Portion 4 of above color coat composition)62.8 ,~ ,, lZ~'7~L
Catalyst solution (described in Portion 4 of above color coat composltion) 80.8 Methanol 198~9 Portion 4 5 Polyvinyl pyrrolldone solution (described in Portion 4 of Example 1 clear coat composition) 20,0 Portion _ Xylene 703.8 Portlon 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and stirred in until homogeneous. Portion 4 was then added and stirred in for 30 minutes. The clear coat enamel was reduced to a spray viscosity of 45 seconds in a No~ 2 Fisher cup with Portion 5 and filtered through a milk filter.
The resulting clear coat enamel had an acrylic/
polymer/melamine formaldehyde resin/p-toluenesulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 57.49/38.33/0.35/2.87/0.96, a silica/binder ratio of 1.9/100 and a calculated solids content of 61.9~.
The above color coat enamel and the above clear coat enamel were sprayed consecutively onto a 20 gauge phosphatized steel panel primed with an alkyd resin type dip primer. The application, solvent flash-ing and baking conditions were similar to those in Example 1. The resultlng dark blue metallic color coat/
clear coat flnish was free of mottling and had an at-tractive, uniform appearance. The coating had a color coat thickness of 0.8 mil, a clear coat thickness of 1.5 mils, a gloss measured at 20 of 89 and a distinct-ness of image of 78.
7~
An acrylic polymer solution was prepared as follows-Grams5 Portion 1 Ethylene glycol monoethyl ether acetate 1180 n-Butyl alcohol 230 Aromatic hydrocarbon solvent boiling at 150-l90~C (~romatic 100) 1920 Total3330 Monomer Mixtu~e Methyl methacrylate 2150 Butyl acrylate 2050 2-Hydroxyethyl acrylate 850 15 Acrylic acid 210 Total 5260 In _ ator Di-t~rt-butyl peroxide 157 Portion 1 was charged into a 1- llter round bottom flask equipped with a thermometer, stirrer, re-flux condenser, two addition funnels, and a heating mantle. The monomer mixture was premixed and charged to one of the addition funnels and the initiator was charged to the other addition funnel. The flask charge was heated to re lux. Addition of the monomer mixture and the initiator was then started simultaneously, and both were added continuously and linearly over a period of 4 hours. The reaction mixture was maintained a-t re-flux during the addi.ion period and then ~or an addi-tional 4 hours. The resulting polymer solution wascooled. It had a solids content of about 6i%.
The polymer was a methyl methacrylate/butyl acrylate/2-hydroxyethyl acrylate/acrylic acid copolymer in a weight ratio of 41/39/16/4. The polymer had a Mw of about 18,000 and a calculated Tg of 5C.
~Z~Z~94 3~
A composite mill base was prepared by charg-a one-half gallon steel mill containing 925 cc of diagonal steel media with the followiny ingre~ients:
Grams Acrylic polymer solution (prepared above) 507.3 Nickel octoate solution in xylene (66% solids) 5.5 Xylene 235.6 n-Butvl acetate 58.9 10 Rutile titanium dloxide pigment 17.3 High color furnace type carbon black pigment 13.8 Quinacridone pigment (Monastral~ Violet RT-887-D) 56.8 Total895.2 The mill was placed on rolls to grind for 64 ho-~rs. The resulting .~ill base was fluld and contained well dispersed pigments. It was filtered off from the grinding media. The mill base had a solids content of 44.8% and contained 9.8% of pigments.
The following light blue metallic color coat enamel was prepared:
Grams Port Acrylic polymer solution (prepared above) 1268.4 25 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids)93.5 Bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate hindered amine light sta-bilizer (Tinuvin~ 292) ~8.0 30 Toluene 148.4 Silicone solution of an organofunctional silicone (Baysilone~ Fluid OL) in xylene (10% solids) 1.4 121Z7'9~
Portion 2 Blue mill base consisting of 18.0% of copper phthalocyanine blue pi~gment, 40~0% of the acrylic polymer solution prepared above, 2.0% of a solution (55%
solids in toluene) of the A-B dispersant described under Portion 1 of Example 1, 30.0% of methyl n-amyl ketone, and 10.0%
of xylene and prepared by grinding in a steel mill with diagonal steel media 335.5 Composite mill base (prepared above) 340.5 Portion 3 Polyurethane solution described under Portion 1 of Example 1 662.0 Portion 4 Bright, non-leafing, acid spot resistant, medium particle size aluminum flake paste (65.5% solids in mineral spirits) 370.0 Di_i50butyl ketone 146.8 Portion 5 ASB solution consisting of 30% of alcohol soluble cellulose acetate butyrate (Eastman CAB-553-0.4) having a viscosity of 0.25 second, 35% of toluene-denatured absolute ethyi alcohol, and 35~ of methyl ethyl ketone 1399.0 High solids, polymeric, methylated mela-mine-formaldehyde resin, 85% solids in n-butanol (Resimene~ 717) llC0.9 Methanol 249.5 25 Methyl ethyl ketone 256.1 Portion 6 Thinner consisting of 50~ vf methyl ethyl ketone, 25~ of ethylene glycol mono-ethyl ether, and 25% of ethylene glycol monobutyl ether acetate 3890 30 Portion 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and each stirred in for 10 minutes. Portion 4 was then added and stirred in vigorously for 1 hour to disperse ~21,~,7'94 the aluminum flakes. Portion 5 was added and ~tirred in ~or , hour. The color coat enamel was reduced to a spray viscosity of 22 seconds in a No. 2 Fisher cup with Porti.on 6 and fIltered through a fine paint strainer.
S The resulting color coat enamel had an acrylic polymer/
polyurethane/melami~e formaldehyde resin/ASB/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 35/15/33/15/1/lr a pigment/binder ratio of 12/100 and a calculated solids content of 30.5%.
10 The following clear coat enamel was prepared:
Grams Portion _ Substituted benzotriazole ultraviolet liqht absorber (Tinuvin~ 328) 61.3 Hindered amine light stabilizer (Tinuvin~
144) 20.6 Aromatic hydrocarbon solvent boiling at 150-1903C (Aromatic 100) 253.2 Acrylic polymer solution of a styrene~
methyl methacrylate/butyl acrylate/2-hydroxyethyl acrylate/acrylic acid (15/28/30~'25/2 weight ratio)copolymer having a Mw of about 20,000 (65~ solids in methyl n-amyl ketone) 1969.6 Portion 2 _ Polymeric, butylated melamine-formaldehyde resin, 58% solids in 32/12 n-butanol/
xylene (Luwipal~ 012/58) 721.1 Polymeric, methylated melamine-formaldehyde resin, 80~ solids in isobutanol (Cymel~ 325) 540.8 Silicone solution (1% solids in xylene of 100 centistoke silicone fluid) 8.6 30 Methanol 18.0 Portion 3 Aromatic hydrocarbon solvent boiling at 150-190C (Aromatic 100) 1750 ~L21~7~4 Portion 1 was charged to a mixing vessel and thoroughly hlended. Portion 2 was added and stirred in for 30 minutes. The clear coat ena~el was reduced to a spray vlscosity of 35 seconds in a No. 2 Fisher cup with Portion 3 and filtered thrcugh a milk filter. The re-sulting clear coat enamel had an acrylic polymer/bu~y-lated melamine ormaldehyde resin/methylated melamine formaldehyde resin/ultraviolet light absorber/hindered amine liyht stabilizer binder ratio of 58.1/18.8/19~4/
2.8/o.s and a calculated solids content of 41.7~.
The above color coat enamel and the above clear coat enamel were sprayed consecutively onto 20 ~auge phosphatized steel panels primed as in Example 1.
The application, solvent flashing ~nd baking conditions were the same as in Example 1, except that the recipro-cating arm carrying the spray guns was run at 1400 inches/
minute, the solvent flash period between the color coat and the clear coat was3 minutes, and the gun-to-panel distance and atomizing air pressure were varie~ as follows in order to determine the appearance uniformity of the finish under an extreme range of application conditions:
9" Panel - The color coat was applied at a gun-to-panel distance of 9 inches usir.g an atomizing air pressure of 55 psi in order to give a coarse spray and a wet, thick color coat film.
12" Panel - The color coat was applied at a gun-to-panel distance of 12 inches using an atomizing air pressure of 65 psi, repre-senting average application conditions.
15" Panel - The color coat was applied at a gun-to-panel distance of 15 inches using an atomizing air pressure of 75 psi in order to give a fine spray and a dry, thin color coat film.
~lZ79~
The clear coat was applied in an identical man-mer to all three panels using a gun-to-panel distance of 1~ inches and an atomizing air pressure of 65 psi, representing average application conditions.
The properties of the three color coat/clear coat panels were as follows:
Property 9" Panel 12" Panel 15" Panel Thickness r mils:
Color coat 1.0 0.80.5 Clear coat 1. 7 1. 71. 7 Gloss measured at 20 94 94 94 Distinctness of image 91 86 88 Head-on brightness 84 85 84 Metallic index 61 61 61 15 MOttllng None NoneNone This light blue metallic color coat/clear coat finish showed a uniform metallic appearance and freedom from mottling when applied under an extreme range of application conditions. It, therefore, had excellent ap~ ation latitude.
EXAMæLE 4 The following white color coat enamel was prepared:
Grams POrtion 1 Xylene 138.4 Substituted benzotriazole ultraviolet light absorber (Tinuvin~ 328~13.3 Bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate hindered amine light stabilizer (Tinuvin~ 292) 13.3 Silicone solution of an organofunctional silicone (Baysilone~ Fluid OL) in xylene (10~ solids) 1.0 Acrylic polymer solution (prepared in Example 3) 91.0 7~
Portion 2 -ASB soluti~n (described under Portion 3 of Example l color coat) 217.7 Polyurethane soluticn (described under Portion l of Example l color coat) 833.6 High solids, polymeric, methylated melamine-formaldehyde resin, 85% sollds in n-butanol (Resimene~ 717) 515.7 Methyl n-amyl ketone 423.7 Methanol 160.7 10 Denatured anhydrous ethyl alcohol 211.2 Portion 3 __ White mill base described under Portion 1 of Example 2 2054.8 Portîon 4 Catalyst solution consisting of 42% of phenyl acid phosphate and 58~ of n-butanol 17.9 Ethylene glycol monoethyl ether acetate 252.2 Methyl isobut~l ketone 54.3 Portion 5 20 Ethylene glycol monoethyl ether acetate 380 Portion l was charged to a mixing vessel and thoroughly blended. Portlons 2, 3, and 4 were added ln turn and each stirred in for 30 minutes. The color coat enamel was recuced to a spray viscosity of 32 seconds in a No. 2 Fisher cup and filtered through a fine paint strainer. The resulting color coat enamel had a low molecular weight acrylic polymer/higher molecular weight acrylic poly~er/polyurethane/melamine formaldehyde resin/ASB~phenyl acid phosphate/ ultra-violet light absorber/hindered amine light stabilizer~)inder ratio of 1~.7/40.0/32.7/5.0/0.6/l.0/l.0, a pigment/binder ratio of 109/lO0 and a calculated solids content of 51.3%.
f79~
The above color coat enamel and the clear coat enamel prepared in E~amPle 3 were sprayed consecu-tively onto a 20 gauge phosphatized steel panel primed as in Example 1. The application, solvent flashing and baking conditions w~re similar to those in Example 1.
T~e resulting wh~te color coat/clear coat finish had a color coat thickness of about 1.4 mils, a clear coat thickness of about 1.8 mils, a gloss measured at 20 of about 95, a distinctness of image of about 90 and a Tukon hardness of about 5 Knoop. It had a uniform color free of any clear coat strike-in effects.
Following are compositional data on the re-sulting color coat enamels:
10 Color Coat A Color ~oat B
Acrylic polymer/polyurethane/ 38~9/],4.6/ 48.6/14.6/
melamine formaldehyde resin/ 34.0/9.7/ 34.0/0/0.8/
ASB/dodecylbenzene sul~onic 0.8/1.0/1.0 I.0/1.0 acid/ultraviolet light absorber/hindered amine light stabiliæer binder ratio Pigment/binder ratio 12.6/100 12.6/100 Calculated solids content 38~8~ 49.6%
The following high solids clear coat enamel was Prepared:
Grams Portion 1 Acrylic polymer solution of a styrene/
methyl methacrylate/butyl acrylate/
2-hydroxyethyl acrylate (15/36/32/
17 weight ratio) copolymer having a ~w of 15,000 (65.1% solid in methyl n-amyl ketone) 1997.0 Methoxy/butoxymethyl melamine 588.8 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids) 200.0 Hindered amine light stabilizer (Tinuvin~
079) solution in xyler,e (40~ solids) 50.0 Silicone solution of an orqanofunctional silicone (Baysilone~ Fluid OL) in xylene (10% solids) 1.7 ~ ,, ~Z~IZ~94 Portion 2 Silica mill base consisting of 8~93%
of a hydrophobic fumed silica (Aerosil~ R-972), 49.60% of methoxy/
buto~ymethyl melamine (Resimene~ 755) and 41.47% of xylene and prepared by sancl grinding 224.0 Portion 3 -Catalyst solution (described under Portion 4 of above color coat compo-sitions) 80.0 10 Methanol 84.8 Portion 4 -Silica bridging agent solution of poly-~inyl pyrrolidone of weight average molecular weight of about 40,000 ~PVP-K-30) in methanol (10% solids) 5.0 Portion 5 Aromatic hydrocarbon solvent boiling at 150-190C (Aromatic 100)782.3 Portion 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and stirred in for 10 minutes each. Portion 4 was added and stirred in for 30 minutes. Finally, the clear coat enamel was reduced to a spray viscosity of 45 seconds in a No. 2 Fisher cup with Portion 5 and filtered through a milk filter.
The resulting clear coat enamel has an acrylic polymer/melamine formaldehyde resin/dodecylbenzene sulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 62.0/33.3/0.8/2.9/1.0, a silica/binder ratio of 1.0/100 and a calculated solids content of 52.7%.
Each of the color coat enamels in combination with the clear coat enamel was sprayed onto 20 gauge phosphatized steel panels primed first with an electro-deposition primer and then with a high solids polyester/
melamine type primer-surfacer. The color coat enamel ~L21Zl~9~
and the clear coat enamel were applied from separate De ~ilbiss Model J~,A-502*pressure feed spray guns each equipped with an FX fluid tip having an orIfice of 0,0425 inch and with a No. 797 air cap. The color coat 5 and clear coat enamels were delivered to the spray guns from separate pressure tanks at controlled flow rates.
The atomizing air pressure was 70 psi at the base of the color coat gun and 60 psi at the base of the clear coat gun.
The color coat/clear coat coating compositions were applied by means of a Spraymation~ automatic panel spray machine. The color coat and clear coat spray guns were mounted side-by-side on a reciprocation arm travel-ling horizontally at a speed of about 764 inches/minute.
The panels were mounted vertically at a distance of 13 inches from the tips of the spray guns on a panel rack which moved vertically from a low to a high position in six 4-inch increments between passes of the spray gun across the pa~els to "index" the panels during the appli-cation of each coat of paint. The color coat enamelwas applied in two coats with a 1 minute solvent flash period between coats. The panels were then dried on the rack for 2 minutes and the clear coat was applied in two coats with a 1 minute solvent flash period between coats. The panels were then dried in a horizontal posi-tion for about 8 minutes, prebaked 15 minutes at 82C
and baked 30 minutes at 131C.
The propexties of the two color coat/clear coat finishes are compared below. The "distinctness of image" was determined b~T means of a Hunter Lab Dori-Gon Meter D47-6~and is a measure of film smoothness, with higher values representing smoother films having a more mirror-like reflectance. The "head-on brightness" and *denotes trade mark ~27~1~
"metallic index" (also called "flake orier~tation index") were measured with a special goniophotometer called Object-Modulated Reflectometer~ ~OMR~ and described in Troy U.S. Patent 4,359,504 issued November 16, 1982.
The head-on brightness was the lightness calculated from the reflectance measured at an angle of 5 from the normal and was a measure of the metallic lightness of the coating when viewed head-on. The metallic index was explained in U.SO 4,359,504 and was a measure of the metallic glamour or degree of two-tone of the coating.
For a given color coat pigmentation higher values of both of these metallic appearance properties result from better Elake orientation and represent a more desirable appearance than lower values.
15 Color Coat A/ Color Coat B/
Clear Coat Clear Coat Properties Finish Finish Thickness, mils:
Color coat 0.77 0.74 Clear coat 1.8 1.8 20 Gloss measured at 20~ 93 76 Distinctness of image 82 42 Head-on brightness 110 69 Metallic index 60 32 Mottling Slight Definite 25 Tukon hardness, Knoop7.9 6.4 The color coat/clear coat finish prepared from color coat A containing ASB had greatly superior gloss, distinctness of image, head-on brightness, metal-lic index and freedom from mottling than the comparable finish prepared from color coat B con-aining no ASB.
Additional coatings were sprayed from the color coat A enamel with the clear coat enamel under the conditions described above at different col~r coat and clear coat film thicknesses and had the following properties:
~271~
2~
Thin Intermediate Thick Property Coatinq Coating _ Coating Thickness t mils:
Color coat 0.53 0.71 1.04 Clear coat 1.7 1.8 2.2 Gloss measured at 2Q93 95 94 Distinctness of image 81 84 84 Head-on brightness 111 112 113 Metallic index 60 61 61 10 Mottling None None None The above coatings prepared from color coat A
had consistent and excellent appearance properties o~er a wide range of color coat film thicknesses at least as great as that encountered in commercial application of this type of finish.
EX~MPLE 2 An acryllc polymer solution was prepared as follows. A 12 liter round bottom flas}; equipped with a thermometer, stirrer, distillation head with reflux condenser, two addition funnels, and a heating mantle was charged wlth 3093 grams of methyl n-amyl ketone.
The following premixed solutions were charged to the addition funnels:
Grams 25 Monomer Mi~ture Styrene 750 ~ethyl methacrylate 750 Butyl acrylate 2000 2-Hydroxyethyl acrylate 1500 Total 5000 Initiator Solution Methyl n-amyl ketone 333 t-Butyl peracetate (75~ solids in mineral spirits) 167 Total 500 2~
The flask charge was heated to reflux.
Addition of the monomer mixture and initiator solution was then started simultaneously. The monomer mix-ture was added linearly over 225 minutes and the initiator solution was added linearly over 240 minutes. The reaction mixture was maintained at reflux during the addition period and for an additional 30 minutes after addition of -the initiator solution was complete. About 1762 grams of volatiles, consisting principalLy of methyl n-amyl ketone, was then distilled off and the ~olution in the flask was cooled. The resul~in~ polymer solution has a solids content of about 75~, The polymer was a styrene/methyl methacrylate/-butyl acrylate/2-hydroxyethyl acrylate copolymer in a weight ratio of 15/15/40/30. The polymer had a Mw of about 6,000 and a calculated Tg of -9C.
The following aluminum flake mill base was prepared:
Grams Portion 1 Acrylic polymer solution ~prepared above) 2780 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30~ solids) 632 25 Hindered amine light stabilizer (Tinuvin~
079) solution in xylene (40% solids) 237 Portion 2 Non-leafinq, acid spot resistant, medium particle size aluminum flake paste (64% solids in mineral spirits) 1851 Portion 1 was charged to a mixing vessel and thoroughly blended. Portion 2 was added, and the mix-ture was stirred vigorously to form a homogeneous dis-persion of the aluminum flakes. The mill base contained 21.5490 of pigment, 37.9% of acrylic polymer, 3.45% of ultraviolet light absorber, and 1.72% of hindered light absorber.
,' 7'~4 The following dark blue metallic color coat enamel was prepared:
Grams Portion 1 ~lue mill base consisting of 12.0% of copper phthalocyanine blue pigment (green shade), 48.0% of the acrylic polymer prepared above and 40.0% of methyl n-amyl ketone and prepared by grinding in a Schold mill 284h.4 Black mill base (described under Por-tion 1 of Example 1 color coat compo-sitions) 373.8 White mill base consisting of 70.0% of rutile titanium dioxide pigment, 10.0%
of the acrylic polymer prepared above, and 20.0% of methyl n-amyl ketone and prepared by sand grinding 37.2 Aluminum flake mill base (~repared above) 179.7 Acrylic polymer solution (prepared above) 246.3 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30~ solids) 179.1 Hindered amine li~ht stabilizer (Tinuvin~
079) solution in xylene (40% solids) 67.5 Portion 2 -Methoxy/butoxymethyl melamine (Resimene~ 755) 1140.0 ASs solution (described under Portion 3 of Example 1 color coat compositions) 500.0 Toluene denatured anhydrous ethyl alcohol 550.2 Portion 3 Amine solution consisting of 25.64% of Amine CS-1135~ 4,4-dimethyyloxazolidine solution in water (78% active) and 74O36% of methanol 44.7 Catalyst solution consisting of 17.8% of p-toluenesulfonic acid, 12.5% of Amine CS-1135~, and 69.7% of methanol60.6 Methanol 198.0 ~ Z~ ~J~9 Portion 4 Thinner consisting of 25% of toluene-denatured anhydrous ethyl alcohol, 25%
of propylene qlycol monomethyl ether, and 50% of xylene 940.0 Portion 1 was charged to a mixing vessel and thoroughly blended. Portion 2 was added and stirred in for 15 minutes. Portion 3 was then added and stirred in for 30 minutes. The color coat enamel was reduced to a stray viscosity of 35 seconds in a No. 2 Fisher cut with Portion 5 and filtered through a fine paint strainer. The resulting color coat enamel had an acrylic polymer/melamine formaldehyde resin/~SB/p-toluenesulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 55.15/36.76/4.8~/
0.35/1.93/0.97, a pigment/binder ratio of 14.5/100 and a calculated solids content at 48.2%.
The following high solids clear coat enamel was prepared:
Grams POrtion 1 -Acrylic polymer solution (prepared above) 3200.0 Silica mill base (described in Portion 2 of Exam~le 1 clear coat composition) 896.0 Methoxy/butoxymethyl melamine (Resimene~ 755) 1155.5 Portion 2 Ultraviole~ light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids) 400.0 Hindered amine light stabilizer (Tinuvin~
079) solution in xylene (40% solids) 100.0 Silicone solution (1% solids in xylene of 100 centistroke silicone fluid) 60.0 Portion 3 Amine solution (described in Portion 4 of above color coat composition)62.8 ,~ ,, lZ~'7~L
Catalyst solution (described in Portion 4 of above color coat composltion) 80.8 Methanol 198~9 Portion 4 5 Polyvinyl pyrrolldone solution (described in Portion 4 of Example 1 clear coat composition) 20,0 Portion _ Xylene 703.8 Portlon 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and stirred in until homogeneous. Portion 4 was then added and stirred in for 30 minutes. The clear coat enamel was reduced to a spray viscosity of 45 seconds in a No~ 2 Fisher cup with Portion 5 and filtered through a milk filter.
The resulting clear coat enamel had an acrylic/
polymer/melamine formaldehyde resin/p-toluenesulfonic acid/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 57.49/38.33/0.35/2.87/0.96, a silica/binder ratio of 1.9/100 and a calculated solids content of 61.9~.
The above color coat enamel and the above clear coat enamel were sprayed consecutively onto a 20 gauge phosphatized steel panel primed with an alkyd resin type dip primer. The application, solvent flash-ing and baking conditions were similar to those in Example 1. The resultlng dark blue metallic color coat/
clear coat flnish was free of mottling and had an at-tractive, uniform appearance. The coating had a color coat thickness of 0.8 mil, a clear coat thickness of 1.5 mils, a gloss measured at 20 of 89 and a distinct-ness of image of 78.
7~
An acrylic polymer solution was prepared as follows-Grams5 Portion 1 Ethylene glycol monoethyl ether acetate 1180 n-Butyl alcohol 230 Aromatic hydrocarbon solvent boiling at 150-l90~C (~romatic 100) 1920 Total3330 Monomer Mixtu~e Methyl methacrylate 2150 Butyl acrylate 2050 2-Hydroxyethyl acrylate 850 15 Acrylic acid 210 Total 5260 In _ ator Di-t~rt-butyl peroxide 157 Portion 1 was charged into a 1- llter round bottom flask equipped with a thermometer, stirrer, re-flux condenser, two addition funnels, and a heating mantle. The monomer mixture was premixed and charged to one of the addition funnels and the initiator was charged to the other addition funnel. The flask charge was heated to re lux. Addition of the monomer mixture and the initiator was then started simultaneously, and both were added continuously and linearly over a period of 4 hours. The reaction mixture was maintained a-t re-flux during the addi.ion period and then ~or an addi-tional 4 hours. The resulting polymer solution wascooled. It had a solids content of about 6i%.
The polymer was a methyl methacrylate/butyl acrylate/2-hydroxyethyl acrylate/acrylic acid copolymer in a weight ratio of 41/39/16/4. The polymer had a Mw of about 18,000 and a calculated Tg of 5C.
~Z~Z~94 3~
A composite mill base was prepared by charg-a one-half gallon steel mill containing 925 cc of diagonal steel media with the followiny ingre~ients:
Grams Acrylic polymer solution (prepared above) 507.3 Nickel octoate solution in xylene (66% solids) 5.5 Xylene 235.6 n-Butvl acetate 58.9 10 Rutile titanium dloxide pigment 17.3 High color furnace type carbon black pigment 13.8 Quinacridone pigment (Monastral~ Violet RT-887-D) 56.8 Total895.2 The mill was placed on rolls to grind for 64 ho-~rs. The resulting .~ill base was fluld and contained well dispersed pigments. It was filtered off from the grinding media. The mill base had a solids content of 44.8% and contained 9.8% of pigments.
The following light blue metallic color coat enamel was prepared:
Grams Port Acrylic polymer solution (prepared above) 1268.4 25 Ultraviolet light absorber solution of a substituted benzotriazole (Tinuvin~
328) in xylene (30% solids)93.5 Bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate hindered amine light sta-bilizer (Tinuvin~ 292) ~8.0 30 Toluene 148.4 Silicone solution of an organofunctional silicone (Baysilone~ Fluid OL) in xylene (10% solids) 1.4 121Z7'9~
Portion 2 Blue mill base consisting of 18.0% of copper phthalocyanine blue pi~gment, 40~0% of the acrylic polymer solution prepared above, 2.0% of a solution (55%
solids in toluene) of the A-B dispersant described under Portion 1 of Example 1, 30.0% of methyl n-amyl ketone, and 10.0%
of xylene and prepared by grinding in a steel mill with diagonal steel media 335.5 Composite mill base (prepared above) 340.5 Portion 3 Polyurethane solution described under Portion 1 of Example 1 662.0 Portion 4 Bright, non-leafing, acid spot resistant, medium particle size aluminum flake paste (65.5% solids in mineral spirits) 370.0 Di_i50butyl ketone 146.8 Portion 5 ASB solution consisting of 30% of alcohol soluble cellulose acetate butyrate (Eastman CAB-553-0.4) having a viscosity of 0.25 second, 35% of toluene-denatured absolute ethyi alcohol, and 35~ of methyl ethyl ketone 1399.0 High solids, polymeric, methylated mela-mine-formaldehyde resin, 85% solids in n-butanol (Resimene~ 717) llC0.9 Methanol 249.5 25 Methyl ethyl ketone 256.1 Portion 6 Thinner consisting of 50~ vf methyl ethyl ketone, 25~ of ethylene glycol mono-ethyl ether, and 25% of ethylene glycol monobutyl ether acetate 3890 30 Portion 1 was charged to a mixing vessel and thoroughly blended. Portions 2 and 3 were added in turn and each stirred in for 10 minutes. Portion 4 was then added and stirred in vigorously for 1 hour to disperse ~21,~,7'94 the aluminum flakes. Portion 5 was added and ~tirred in ~or , hour. The color coat enamel was reduced to a spray viscosity of 22 seconds in a No. 2 Fisher cup with Porti.on 6 and fIltered through a fine paint strainer.
S The resulting color coat enamel had an acrylic polymer/
polyurethane/melami~e formaldehyde resin/ASB/ultraviolet light absorber/hindered amine light stabilizer binder ratio of 35/15/33/15/1/lr a pigment/binder ratio of 12/100 and a calculated solids content of 30.5%.
10 The following clear coat enamel was prepared:
Grams Portion _ Substituted benzotriazole ultraviolet liqht absorber (Tinuvin~ 328) 61.3 Hindered amine light stabilizer (Tinuvin~
144) 20.6 Aromatic hydrocarbon solvent boiling at 150-1903C (Aromatic 100) 253.2 Acrylic polymer solution of a styrene~
methyl methacrylate/butyl acrylate/2-hydroxyethyl acrylate/acrylic acid (15/28/30~'25/2 weight ratio)copolymer having a Mw of about 20,000 (65~ solids in methyl n-amyl ketone) 1969.6 Portion 2 _ Polymeric, butylated melamine-formaldehyde resin, 58% solids in 32/12 n-butanol/
xylene (Luwipal~ 012/58) 721.1 Polymeric, methylated melamine-formaldehyde resin, 80~ solids in isobutanol (Cymel~ 325) 540.8 Silicone solution (1% solids in xylene of 100 centistoke silicone fluid) 8.6 30 Methanol 18.0 Portion 3 Aromatic hydrocarbon solvent boiling at 150-190C (Aromatic 100) 1750 ~L21~7~4 Portion 1 was charged to a mixing vessel and thoroughly hlended. Portion 2 was added and stirred in for 30 minutes. The clear coat ena~el was reduced to a spray vlscosity of 35 seconds in a No. 2 Fisher cup with Portion 3 and filtered thrcugh a milk filter. The re-sulting clear coat enamel had an acrylic polymer/bu~y-lated melamine ormaldehyde resin/methylated melamine formaldehyde resin/ultraviolet light absorber/hindered amine liyht stabilizer binder ratio of 58.1/18.8/19~4/
2.8/o.s and a calculated solids content of 41.7~.
The above color coat enamel and the above clear coat enamel were sprayed consecutively onto 20 ~auge phosphatized steel panels primed as in Example 1.
The application, solvent flashing ~nd baking conditions were the same as in Example 1, except that the recipro-cating arm carrying the spray guns was run at 1400 inches/
minute, the solvent flash period between the color coat and the clear coat was3 minutes, and the gun-to-panel distance and atomizing air pressure were varie~ as follows in order to determine the appearance uniformity of the finish under an extreme range of application conditions:
9" Panel - The color coat was applied at a gun-to-panel distance of 9 inches usir.g an atomizing air pressure of 55 psi in order to give a coarse spray and a wet, thick color coat film.
12" Panel - The color coat was applied at a gun-to-panel distance of 12 inches using an atomizing air pressure of 65 psi, repre-senting average application conditions.
15" Panel - The color coat was applied at a gun-to-panel distance of 15 inches using an atomizing air pressure of 75 psi in order to give a fine spray and a dry, thin color coat film.
~lZ79~
The clear coat was applied in an identical man-mer to all three panels using a gun-to-panel distance of 1~ inches and an atomizing air pressure of 65 psi, representing average application conditions.
The properties of the three color coat/clear coat panels were as follows:
Property 9" Panel 12" Panel 15" Panel Thickness r mils:
Color coat 1.0 0.80.5 Clear coat 1. 7 1. 71. 7 Gloss measured at 20 94 94 94 Distinctness of image 91 86 88 Head-on brightness 84 85 84 Metallic index 61 61 61 15 MOttllng None NoneNone This light blue metallic color coat/clear coat finish showed a uniform metallic appearance and freedom from mottling when applied under an extreme range of application conditions. It, therefore, had excellent ap~ ation latitude.
EXAMæLE 4 The following white color coat enamel was prepared:
Grams POrtion 1 Xylene 138.4 Substituted benzotriazole ultraviolet light absorber (Tinuvin~ 328~13.3 Bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) decanedioate hindered amine light stabilizer (Tinuvin~ 292) 13.3 Silicone solution of an organofunctional silicone (Baysilone~ Fluid OL) in xylene (10~ solids) 1.0 Acrylic polymer solution (prepared in Example 3) 91.0 7~
Portion 2 -ASB soluti~n (described under Portion 3 of Example l color coat) 217.7 Polyurethane soluticn (described under Portion l of Example l color coat) 833.6 High solids, polymeric, methylated melamine-formaldehyde resin, 85% sollds in n-butanol (Resimene~ 717) 515.7 Methyl n-amyl ketone 423.7 Methanol 160.7 10 Denatured anhydrous ethyl alcohol 211.2 Portion 3 __ White mill base described under Portion 1 of Example 2 2054.8 Portîon 4 Catalyst solution consisting of 42% of phenyl acid phosphate and 58~ of n-butanol 17.9 Ethylene glycol monoethyl ether acetate 252.2 Methyl isobut~l ketone 54.3 Portion 5 20 Ethylene glycol monoethyl ether acetate 380 Portion l was charged to a mixing vessel and thoroughly blended. Portlons 2, 3, and 4 were added ln turn and each stirred in for 30 minutes. The color coat enamel was recuced to a spray viscosity of 32 seconds in a No. 2 Fisher cup and filtered through a fine paint strainer. The resulting color coat enamel had a low molecular weight acrylic polymer/higher molecular weight acrylic poly~er/polyurethane/melamine formaldehyde resin/ASB~phenyl acid phosphate/ ultra-violet light absorber/hindered amine light stabilizer~)inder ratio of 1~.7/40.0/32.7/5.0/0.6/l.0/l.0, a pigment/binder ratio of 109/lO0 and a calculated solids content of 51.3%.
f79~
The above color coat enamel and the clear coat enamel prepared in E~amPle 3 were sprayed consecu-tively onto a 20 gauge phosphatized steel panel primed as in Example 1. The application, solvent flashing and baking conditions w~re similar to those in Example 1.
T~e resulting wh~te color coat/clear coat finish had a color coat thickness of about 1.4 mils, a clear coat thickness of about 1.8 mils, a gloss measured at 20 of about 95, a distinctness of image of about 90 and a Tukon hardness of about 5 Knoop. It had a uniform color free of any clear coat strike-in effects.
Claims (19)
1. An acrylic color coat enamel coating composition comprising about 25-50% by weight of a binder of film-forming constituents and correspondingly about 50-75% by weight of a volatile organic solvent carrier at spray viscosity and containing in addition about 2-150% by weight, based on the weight of the binder, of pigment wherein the binder of film-forming constituents consists essentially of about 20-70% by weight, based on the weight of the binder, of an acrylic polymer, said acrylic polymer consisting essentially of 50-90% by weight of an alkyl methyacrylate or an alkyl acrylate each having 1-12 carbon atoms in the alkyl groups or a mixture thereof and 10-50% by weight of a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl groups or a mixture thereof and in which the acrylic polymer has a weight average molecular weight of about 2500-25,000 and a glass transition temperature of about -20°C to +25°C; about 0-40% by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resin; about 25-40% by weight, based on the weight of the binder, of an alkylated melamine formaldehyde crosslinking agent; and about 4-20% by weight, based on the weight of binder, of a rheology control agent consisting essentially of an alcohol soluble cellulose acetate butyrate having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second.
2. The coating composition of Claim 1 wherein the acrylic polymer contains in addition about 0.1-5% by weight, based on the weight of the acrylic polymer of an ethylenically unsaturated carboxylic acid.
3. The coating composition of Claim 1 wherein the crosslinking agent is fully alkylated melamine formaldehyde resin having 1-4 carbon atoms in the alkyl groups.
4. The coating composition of Claim 4 wherein the crosslinking agent is a fully alkylated methoxy/butoxymethyl melamine.
5. The coating composition of Claim 1 wherein the crosslinking agent is a partially alkylated, polymeric melamine formaldehyde resin having 1-4 carbon atoms in the alkyl groups.
6. The coating composition of Claim 1 wherein the volatile organic solvent carrier consists essential-ly of about 30-60% by weight, based on the weight of the total solvent, of methanol, ethanol, acetone, methyl ethyl ketone or a mixture thereof and about 40-70% by weight, based on the weight of the total solvent, of methyl n-amyl ketone, n-butyl acetate, ethylene glycol monobutyl ether acetate, an approximately equivolume blend of ethylene glycol monoethyl ether acetate with diisobutyl ketone or a mixture thereof.
7. The coating composition of Claim 6 wherein the volatile organic solvent carrier contains in addition 10-20% by weight, based on the weight of the total solvent, of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether or a mixture thereof.
8. The coating composition of Claim 1 con-taining 0.1-2% by weight, based on the weight of the binder, of an acid catalyst.
9. The coating composition of Claim 3 con-taining 0.1-2% by weight, based on the weight of the binder, of a alkyl sulfonic acid or an aryl sulfonic acid catalyst each fully neutralized with an amine.
10. The coating composition of Claim 9 in which the amine is n-propylamine or 4,4-dimethyloxyazolidine.
11. The coating composition of Claim 5 con-taining 0.1-2% by weight, based on the weight of the binder, of phosphoric acid, an alkyl acid phosphate or an aryl acid phosphate.
12. The coating composition of Claim 1 con-taining about 0.1-4% by weight, based on the weight of the binder, of an ultraviolet light absorber.
13. The coating composition of Claim 1 con-taining about 0.1-2% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
14. The coating composition of Claim 1 con-taining aluminum flake pigment.
15. A substrate having a cured finish com-prising the color coat coating composition of Claim 1 firmly adhered thereto and a clear coat firmly adhered to the color coat coating composition of Claim 1.
16. An acrylic color coat enamel coating composition comprising about 28-45% by weight of a binder of film-forming constituents and correspondingly about 55-72% by weight of a volatile organic solvent carrier at spray viscosity and contaning in addition about 2-150% by weight, based on the weight of the binder, of pigment wherein the binder of film-forming constituents consists essentially of about 20-65% by weight, based on the weight of the binder, of an acrylic polymer, said acrylic polymer consisting essentially of 50-90% by weight of an alkyl methacrylate or an alkyl acrylate each having 1-12 carbon atoms in the alkyl groups or a mixture thereof and 10-50% by weight of a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl groups or a mixture thereof and in which the acrylic polymer has a weight average molecular weight of about 2500-25,000 and a glass transition temperature of about -20°C to +25°C; about 0-40% by weight, based on the weight of the binder, of a hydroxy-terminate polyester urethane resin; about 30-40% by weight, based on the weight of the binder, of an alkylate melamine formaldehyde crosslinking agent; and about 4-20% by weight, based on the weight of the binder, of a rheology control agent consisting essentially of an alcohol soluble cellulose acetate butyrate having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second.
17. An acrylic color coat enamel coating composition comprising about 33-45% by weight of a binder of film-forming constituents and correspondingly about 55-67% by weight of a volatile organic solvent carrier at spray viscosity and containing in addition about 2-150% by weight, based on the weight of the binder, of pigment wherein the binder of film-forming constituents consists essentially of about A. 20-66% by weight, based on the weight of the binder, of an acrylic polymer consisting essentially of (1) about 40-80% by weight, based on the weight of the acrylic polymer, of an alkyl methacrylate or an alkyl acrylate each having 1-6 carbon atoms in the alkyl groups or a mixture thereof, (2) about 20-40% by weight, based on the weight of the acrylic polymer, of a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl groups or a mixture thereof, (3) 0-20% by weight, based on the weight of the acrylic polymer, of styrene; and wherein the acrylic polymer has a weight average molecular weight of about 3000-12,000 and a glass transition temperature of about -20°C to +25°C;
B. 0-20% by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resin having a number average molecular weight of about 4000-10,000;
C. 30-40% by weight, based on the weight of the binder, of a fully alkylated melamine formaldehyde crosslinking agent having 1-4 carbon atoms in the alkyl groups;
D. 4-20% by weight, based on the weight of the binder, of an alcohol soluble cellulose acetate butyrate rheology control agent having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second;
E. 0.3-10% by weight, based on the weight of the binder, of an alkyl sulfonic acid or an aryl sulfonic acid catalyst each fully neutralized with n-propylamine or 4,4-dimethyloxazolidine;
F. 0-3% by weight, based on the weight of the binder, of an ultraviolet light absorber; and G. 0-2% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
B. 0-20% by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resin having a number average molecular weight of about 4000-10,000;
C. 30-40% by weight, based on the weight of the binder, of a fully alkylated melamine formaldehyde crosslinking agent having 1-4 carbon atoms in the alkyl groups;
D. 4-20% by weight, based on the weight of the binder, of an alcohol soluble cellulose acetate butyrate rheology control agent having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second;
E. 0.3-10% by weight, based on the weight of the binder, of an alkyl sulfonic acid or an aryl sulfonic acid catalyst each fully neutralized with n-propylamine or 4,4-dimethyloxazolidine;
F. 0-3% by weight, based on the weight of the binder, of an ultraviolet light absorber; and G. 0-2% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
18. An acylic color coat enamel coating composition comprising about 28-40% by weight of a binder of film-forming constituents and correspondingly about 60-72% by weight of a volatile organic solvent carrier at spray viscosity and containing in addition about 2-150% by weight, based on the weight of the binder, of pigment wherein the binder of film-forming constituents consists essentially of about A. 20-58% by weight, based on the weight of the binder, of an acrylic polymer consisting essentially of (1) about 50-88%, based on the weight of the acrylic polymer, of an alkyl methacrylate or an alkyl acrylate each having 1-6 carbon atoms in the alkyl groups or a mixture thereof, (2) about 10-25% by weight, based on the weight of the acrylic polymer, of a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate each having 2-4 carbon atoms in the hydroxyalkyl groups or a mixture thereof, (3) about 2-5% by weight, based on the weight of the acrylic polymer, of acrylic acid or methacrylic acid, (4) 0-20% by weight, based on the weight of the acrylic polymer, of styrene; and wherein the acrylic polymer has a weight average molecular weight of about 10,000-25,000 and a glass transition temperature of about -20°C to +25°C;
B. 10-40% by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resin having a number average molecular weight of about 4000-10,000, C. 28-38% by weight, based on the weight of the binder, of a partially alkylated, polymeric melamine formaldehyde resin having 1-4 carbon atoms in the alkyl groups;
D. 4-20% by weight, based on the weight of the binder, of an alcohol soluble cellulose acetate butyrate rheology control agent having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second;
E. 0-2% by weight, based on the weight of the binder of a catalyst comprising phosphoric acid, an alkyl acid phosphate or an aryl acid phosphate;
F. 0-3% by weight, based on the weight of the binder, of an ultraviolet light absorber; and G. 0-2% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
B. 10-40% by weight, based on the weight of the binder, of a hydroxy-terminated polyester urethane resin having a number average molecular weight of about 4000-10,000, C. 28-38% by weight, based on the weight of the binder, of a partially alkylated, polymeric melamine formaldehyde resin having 1-4 carbon atoms in the alkyl groups;
D. 4-20% by weight, based on the weight of the binder, of an alcohol soluble cellulose acetate butyrate rheology control agent having a butyryl content of about 45-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second;
E. 0-2% by weight, based on the weight of the binder of a catalyst comprising phosphoric acid, an alkyl acid phosphate or an aryl acid phosphate;
F. 0-3% by weight, based on the weight of the binder, of an ultraviolet light absorber; and G. 0-2% by weight, based on the weight of the binder, of a hindered amine light stabilizer.
19. The coating composition of Claim 18 in which the acrylic polymer consists essentially of 25-55%
by weight of methyl methacrylate, 30-50% by weight of butyl acrylate, 12-20% by weight of 2-hydroxyethyl acrylate and 3-5% by weight of acrylic acid and in which the acrylic polymer has a weight average molecular weight of about 15,000-20,000 and a glass transition temperature of about -15°C to +25°C.
by weight of methyl methacrylate, 30-50% by weight of butyl acrylate, 12-20% by weight of 2-hydroxyethyl acrylate and 3-5% by weight of acrylic acid and in which the acrylic polymer has a weight average molecular weight of about 15,000-20,000 and a glass transition temperature of about -15°C to +25°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000446455A CA1212794A (en) | 1984-01-31 | 1984-01-31 | High solids color coat containing alcohol soluble cellulose acetate butyrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000446455A CA1212794A (en) | 1984-01-31 | 1984-01-31 | High solids color coat containing alcohol soluble cellulose acetate butyrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1212794A true CA1212794A (en) | 1986-10-14 |
Family
ID=4127070
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000446455A Expired CA1212794A (en) | 1984-01-31 | 1984-01-31 | High solids color coat containing alcohol soluble cellulose acetate butyrate |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1212794A (en) |
-
1984
- 1984-01-31 CA CA000446455A patent/CA1212794A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4451597A (en) | High solids color coat containing alcohol soluble cellulose acetate butyrate | |
| EP0217385B1 (en) | Method of forming metallic coatings | |
| CA1195035A (en) | High solids coating composition of an enamel containing a rheology control additive of silica and polyethylene glycol | |
| CA1206670A (en) | Additive for coating compositions of silica and a fluorinated ethylene oxide polymer | |
| CA1055178A (en) | Thermosetting powder coating compsition of an acrylic polymer, a hydroxy functional plasticizer and a blocked polyisocyanate cross-linking agent | |
| US4455331A (en) | Coating composition containing a rheology control additive of silica and polyvinyl pyrrolidone | |
| CA1162682A (en) | High solids coating composition of a blend of a low molecular weight acrylic polymer and a medium molecular weight acrylic polymer and an alkylated melamine cross-linking agent | |
| WO2007043633A9 (en) | Effect pigment-containing, water-borne base coating compositions | |
| JP2009505807A (en) | Method for forming glittering multilayer coating film | |
| US4404248A (en) | Clear coat/color coat finish from a high solids coating composition of a blend of a low molecular weight acrylic polymer and a medium molecular weight acrylic polymer and an alkylated melamine cross-linking agent | |
| US4358510A (en) | Metallic painting | |
| JP2006095522A (en) | Method for coating water-based coating material | |
| EP1182236B1 (en) | Vinyl resin additive comprising urethane functionality | |
| DE69810801T2 (en) | COATING COMPOSITIONS CONTAINING A NON-WATER DISPERSED POLYMER, SILANE-FUNCTIONAL ACRYLIC RESIN AND TRIAZINE | |
| EP0569761B1 (en) | Process for making wrinkle-free coating using solventborne clearcoat composition over waterborne basecoat composition | |
| US5912052A (en) | Method of pattern coating | |
| CA2620913A1 (en) | Method of forming a multi-layer coating on automobile bodies without a primer bake | |
| US4610898A (en) | Process for bake coating the surfaces of solid substances | |
| FI97391B (en) | Coating compositions, process for making and using them, especially for external coating of press-drawn cans | |
| EP0136251B2 (en) | Super jet black coatings | |
| CA1212794A (en) | High solids color coat containing alcohol soluble cellulose acetate butyrate | |
| CN110655857B (en) | Water-based colored paint suitable for wet spraying process and application thereof | |
| CN110773402B (en) | Multilayer coating and method of forming the same | |
| CN115637079A (en) | Low-VOC amino baking varnish composition, preparation method and application thereof | |
| EP0835913B1 (en) | Aqueous colored coating composition |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |