Abstract:
Pigmented non-aqueous dispersed polymer compositions containing melamine-formaldehyde resin are disclosed. The dispersed polymer and the soluble stabilizer polymer are both cross-linkable with the malamine resin to give improved thermosetting paints, especially for metal surfaces such as automobile bodies.

Description:
This is a continuation of application Ser. No. 446,610 filed Feb. 28, 1974 and now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to thermosetting coating composition containing acrylic copolymers dispersed in a non-aqueous medium and to metal substrates coated therewith. The use of non-aqueous dispersions of acrylic polymers in coating compositions have received considerable attention in recent years as a means of applying film forming materials because such dispersions require the use of smaller amounts of volatile solvents, which results in less air pollution from the coating process, and also because it permits the application of fewer coats of the paint or finish to obtain adequate film thicknesses. The present invention relates primarily to non-aqueous acrylic polymer paints, or finishes, which are thermosetting. Such compositions as described in the prior art comprise pigmented non-aqueous dispersions wherein the dispersed acrylic polymer contains hydroxyl groups which are cross-linkably reactive with aminoplast resins, especially melamine formaldehyde resin. The dispersed polymer may also contain a small amount of free carboxyl groups along the polymer chain. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved coating compositions, or paints, especially for metal substrates such as automobile bodies, by providing pigmented non-aqueous dispersions, containing aminoplast resin cross-linking agent, and a cross-linkable dispersed acrylic polymer, wherein the dispersed acrylic polymer is made in the presence of a solution of a preformed cross-linkable acrylic polymer. The preformed cross-linkable soluble polymer is comprised of preferably 40 to 70%, by weight of copolymerized solubilizing monomer such as lauryl methacrylate. Paints made in accordance with the invention have good storage stability in that they usually remain in suspension indefinitely even at spray viscosity and stay smooth and free of seed. In the infrequent instances when settling occurs, the sediment is soft and the paint is easily stirred to its original condition. When films of the paint are applied to metal substrates and the films are cured at a relatively low bake of 250° F. for 30 minutes, the thermoset coatings have good gloss, good adhesion, good acid spotting resistance, humidity resistance, excellent outdoor durability and hardness. The compositions have excellent application properties in that they have good build and antisag qualities even when blended with solution vehicles. The unexpectedly good resistance properties of the low-baked film makes the novel paints more useful as low-baked automotive repair finishes, i.e., finishes baked at 180° to 210° F. for 20 minutes using an acid catalyst. Such low-baked repair films prepared from paints of the present invention show unexpectedly good hardness, adhesion and resistance to humidity. 
     DESCRIPTION OF THE INVENTION 
     In accordance with the invention, a non-aqueous dispersion of a cross-linkable acrylic polymer is prepared by copolymerizing a mixture of suitable monoethylenically unsaturated monomers, including at least one hydroxyalkyl acrylic or methacrylic ester, or a glycidyl ester of acrylic or methacrylic acid. The copolymerization is carried out in the presence of a preformed solution of a cross-linkable stabilizer polymer comprised of at least 30% by weight of copolymerized solubilizing monomer such as lauryl methacrylate and a minor amount, especially 10 to 30%, of at least one monoethylenically unsaturated monomer containing a group which is cross-linkable with aminoplast resins. Suitable monomers containing cross-linkable groups include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycidyl acrylate and glycidyl methacrylate. Polymers containing such monomers are commonly referred to in the art as thermosetting acrylic polymers, or TSA polymers, The stabilizer polymer will usually contain minor amounts of other monoethylenically unsaturated monomers as hereinafter described. 
     The stabilizer polymers useful in the invention consist of 30 to 90% by weight, preferably 40 to 70% by weight of copolymerized solubilizing monomers, i.e., alkyl and cycloalkyl esters of acrylic and methacrylic acids wherein the alkyl or cycloalkyl group contains four or more carbon atoms; preferably at least about half of the solubilizing monomers is lauryl methacrylate. The stabilizer polymer also contains 10 to 30% by weight, preferably about 15 to 20% by weight of a monomer which contains a cross-linkable group and is of the group consisting of hydroxy propyl acrylate, hydroxy ethyl methacrylate, hydroxy propyl methacrylate, hydroxy ethyl acrylate and glycidyl methacrylate or acrylate, 0 to 40% by weight, preferably 15 to 20% by weight of styrene, or a derivative of styrene, especially an alkyl substituted styrene, such as vinyl toluene, and 0 to 3% by weight, preferably 0.5 to 1.5% by weight of acrylic acid, or similar α,β-unsaturated acid, such as methacrylic acid. This amount of acidic monomer is in addition to that in the hydroxyalkyl ester monomer, which usually is about 4% by weight of the hydroxyalkyl monomer. In compositions using glycidyl esters instead of hydroxyalkyl monomers, the preferred acid content would be zero or close to zero. Preferred solubilizing monomers include lauryl methacrylate, butyl and isobutyl acrylate, butyl and isobutyl methacrylate, 2-ethyl hexyl acrylate, 2-ethyl hexyl methacrylate, and isobornyl methacrylate. 
     The stabilizer is prepared in a solvent which is a solvent for the copolymer at 40 to 60% solids and the solvent is preferably aliphatic hydrocarbon or a mixture of aliphatic hydrocarbons with minor amounts of the glycol ethers, or the acetate esters of the glycol ethers (especially of the monoethyl ether), or aromatic hydrocarbons, or n-butanol, or several of these. The aliphatic hydrocarbon preferably should have a boiling point in the range of 130° to 140° C. 
     Copolymerization of the monomers to form the stabilizer polymer is carried out in conventional manner using free radical catalysts at temperatures on the order of 120° to 140° C., preferably close to 130° C., until substantially all of the monomer charge has been polymerized and the solids content is close to theoretical. Tertiary butyl perbenzoate is an especially preferred catalyst because it is a liquid and is readily miscible with the solvents used. Although it is unnecessary to heat the polymerization longer than is needed for complete conversion of monomer, it has been found that heating at reflux for extended periods of time, up to 4 hours, after the last catalyst addition is desirable in that it makes the stabilizer more effective even though the solids and viscosity of the product do not change appreciably. 
     The acid value of the stabilizer copolymer is generally in the range of 4 to 28, preferably 8 to 16, based on solids when hydroxyalkyl monomers are used. When glycidyl monomers are used, the acid value should be zero or close to zero. 
     The dispersion polymer composition is prepared by copolymerizing 50 to 90% by weight, preferably 65 to 75% by weight of the desired monomers in solution in the presence of 10 to 50% by weight, preferably 25 to 35% by weight of a dissolved stabilizer polymer as described above. The finished dispersion polymer composition contains 40 to 70% solids, by weight, and preferably 50 to 55% for best stability and working properties. 
     The dispersed polymer component consists of 30 to 80% by weight of a lower alkyl acrylate or methacrylate, preferably 45 to 55% by weight; 0 to 50% by weight, preferably 20 to 35% by weight, of styrene or vinyl toluene or similar monomers; 10 to 30% by weight, preferably 15 to 25% by weight, of a hydroxy lower alkyl acrylate or methacrylate, especially hydroxypropyl acrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate and hydroxy ethyl methacrylate or a glycidyl ester, especially glycicyl acrylate and glycidyl methacrylate; 0 to 3% by weight, preferably 0.5 to 2% by weight, of acrylic or methacrylic acid. The amount of acid monomer refers to the amount in addition to that which is present in the hydroxyalkyl monomer, which usually is about 4% by weight of the hydroxyalkyl monomer. In compositions using glycidyl ester instead of hydroxyalkyl monomer the preferred acid content would be zero or close to zero. Lower alkyl as used herein means alkyl groups containing one to four carbon atoms. Ordinarily the use of more than a few percent of the higher acrylates cannot be tolerated because they tend to make the polymer too soluble. 
     Copolymerization of the desired dispersed polymer monomers in solution with the desired amount of stabilizer copolymer is carried out with conventional addition polymerization catalysts in the usual manner, e.g., at reflux temperature and with constant stirring. The acid value of the resulting dispersion polymer composition is usually on the order of 5 to 30 on a solids basis, preferably 10 to 20, when hydroxyalkyl esters are used; when glycidyl esters are used, the acid value should be zero or close to zero. The dispersion polymer composition consists of, on a solids basis 50 to 90% by weight dispersed polymer and 10 to 50% by weight of stabilizer polymer, but preferably about 65 to 75% by weight of dispersed polymer and 25 to 35% by weight of stabilizer polymer. 
     The dispersion polymer composition is formulated into a paint by dispersing the desired pigment in the composition and adding a solution of melamine formaldehyde as cross-linking agent for the stabilizer polymer and the dispersed polymer. Pigment content may range from about 1.5% to 25% by weight, on solids. Advantageously, the pigment is added as a dispersion in a solution of an acrylic resin which is preferably a solution of a thermosetting, i.e., cross-linkable, acrylic polymer in a high boiling solvent. The thermosetting acrylic polymer may be similar to the stabilizer copolymer or it may be any other suitable acrylic polymer, preferably a thermosetting acrylic polymer, that can serve as a pigment dispersion vehicle for the pigment. 
     In general, the finished paint contains melamine resin, dispersed TSA polymer, and soluble TSA polymer as binder components. The soluble TSA polymer comprises the cross-linkable acrylic polymer used as stabilizer and any other soluble cross-linkable acrylic such as that included as part of the pigment dispersion. The ratios of these three components, on a weight basis, will usually be 25 to 35% melamine resin, 10 to 50% dispersed polymer and 20 to 55% soluble acrylic polymer. The total solids of the paint at spray viscosity normally will be about 40 to 50%, including pigment. The binder resin to pigment ratio in the finished paint will be from about 50 to 1 to about 3 to 1, on a weight basis. 
     In the present application the term &#34;dispersion polymer composition&#34; is used to mean the composition which is prepared by copolymerizing acrylic monomers, to obtain insoluble polymers, in the presence of a dissolved acrylic polymer which acts as a stabilizer to keep the insoluble dispersed polymer in dispersed form. Such a dispersion polymer composition is sometimes referred in the art as &#34;non-aqueous dispersion,&#34; or is abbreviated as N A D. Such dispersions are also sometimes referred to as &#34;organosols.&#34; 
     Paints formulated in accordance with the invention, using the non-aqeuous dispersion polymer compositions described above and in the examples, will contain volatile organic solvents consisting predominantly of aliphatic hydrocarbons, pigment, and thermosetting film-forming binder consisting of a mixture of 25 to 35% by weight of dissolved butylated melamineformaldehyde resin and 65 to 75% by weight of thermosetting, cross-linkable acrylic polymers. One-fourth to three-fourths of the thermosetting acrylic polymer is insoluble in the vehicle and is stably dispersed in the vehicle. 
    
    
     The following examples in which the parts are by weight will further illustrate the invention. 
     EXAMPLE 1 
     A mixture of 
     
         ______________________________________Lauryl methacrylate       625 partsStyrene                   150 partsHydroxypropyl methacrylate                     200 partsAcrylic acid               15 partsAliphatic hydrocarbon, B. P. about 130° C.(e.g. Espesol 260 F.)     100 partsTert. Butyl perbenzoate    15 parts______________________________________ 
    
     was added to a refluxing and constantly stirred mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    500 partsCellosolve               100 partsButyl cellosolve         100 parts______________________________________ 
    
     at a constant rate over a period of 31/2 hours. Refluxing was continued for 1/2 hour and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTert. Butyl perbenzoate   5 parts______________________________________ 
    
     was added over a 15 minute period and then refluxing was continued for another 2 hours. The reaction mixture was reduced with 120 parts of aliphatic hydrocarbon (as above) to give a stabilizer polymer solution having a Gardner-Holt viscosity of P - Q, a non-volatile content of 49% and an acid value of 16.1 based on non-volatile. The polymer solution is used as a stabilizer for preparing dispersion polymer compositions. 
     A dispersion polymer composition was made by adding a mixture of 
     
         ______________________________________Methyl methacrylate      274 partsStyrene                  172 partsHydroxypropyl methacrylate                    115 partsAcrylic acid              13 partsAliphatic hydrocarbon (as above)                    116 partsTert. Butyl perbenzoate   16 parts______________________________________ 
    
     to a refluxing and constantly stirred mixture of 
     
         ______________________________________Stabilizer polymer solution (as above)                     500 partsAliphatic hydrocarbon (as above)                     164 parts______________________________________ 
    
     over a period of 31/2 hours at a constant rate of addition. Refluxing was continued for 30 minutes and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTert. Butyl perbenzoate  10 parts______________________________________ 
    
     was added at a uniform rate over 30 minutes. Refluxing and strong agitation were continued another 2 hours and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsn-Butanol                85 partsButyl Cellosolve         55 parts______________________________________ 
    
     was added at a uniform rate over 15 minutes and then the batch was cooled to room temperature to give a finished dispersion composition having a viscosity of 66 seconds (No. 4 Ford Cup) at 74° F., a non-volatile content of 51.1% and an acid value of 20.3 based on non-volatiles. The dispersion polymer composition consists of 30% dissolved polymer (stabilizer) and 70% dispersed polymer on a non-volatile basis. The overall composition of the non-volatile is 
     
         ______________________________________Methyl methacrylate      33.5%Lauryl methacrylate      18.8%Styrene                  25.5%Hydroxy propyl methacrylate                    20.2%Acrylic acid              2.0%______________________________________ 
    
     A paint was prepared by mixing 
     
         ______________________________________Dispersion polymer composition,at 51% non-volatiles   22 partsPigment dispersion (10.0% aluminumpowder and 5.5% quinacridone magentapigment dispersed in 22.8% solublethermosetting acrylic polymer,21.1% butyl cellosolve acetate,15.4% aromatic naphtha, 9.2% xylene,5.4% mineral spirits, 1.4% isopropanol,and 9.2% n-Butanol)    45 partsMelamine Resin Solution(61% butylated melamine formaldehyderesin in a mixture of n-Butanol andaliphatic hydrocarbon) 87 partsEspesol 260 F. (aliphatichydrocarbon, B.P. about 130° C.)                  85 partsButyl ether of ethylene glycol                  10 parts2 - Ethyl hexyl alcohol                  10 parts______________________________________ 
    
     The paint had a viscosity of 17 seconds 77° F. (Ford No. 4 Cup) and was suitable for application by spraying. It had a solids content of 39.9% (calculated) and a pigment to binder ratio of 4/100. The paint showed no settling and was free of seeds, i.e., it was smooth and stable and did not become seedy on further reduction with solvents. A panel sprayed with the paint was baked 30 minutes at 250° F. and had a 20° gloss at 75 at 1.7 mils film thickness. 
     The soluble thermosetting acrylic polymer used in the pigment dispersion was a copolymer of 24% lauryl methacrylate, 24% 2-ethyl hexyl methacrylate, 20% hydroxyethyl methacrylate, 30.5% styrene and 1.5% methacrylic acid. 
     EXAMPLE 2 
     Using a procedure similar to that of Example 1, a 50% stabilizer polymer solution in a mixture of 4 parts Espesol 260° F, 0.5 part cellosolve and 0.5 part butyl cellosolve was prepared from a mixture of 
     
         ______________________________________Lauryl methacrylate     32  partsIsobornyl methacrylate  31.5 partsStyrene                 15.0 partsHydroxypropyl methacrylate                   20.0 partsAcrylic acid             1.5 parts______________________________________ 
    
     This stabilizer solution was substituted for that used in Example 1 to obtain non-aqueous dispersion polymer composition having a viscostiy of 40 seconds (No. 4 Ford Cup) at 77° F., a non-volatile content of 51% and an acid value of 19 based on non-volatiles. The paint prepared from the non-aqueous polymer composition had desirable properties similar to those of the paint of Example 1. 
     EXAMPLE 3 
     A mixture of 
     
         ______________________________________Lauryl methacrylate       678 partsStyrene                   150 partsHydroxypropyl methacrylate                     150 partsAcrylic acid               12 partsAliphatic hydrocarbon (as in Example 1)                     100 partsTertiary butyl perbenzoate                      15 parts______________________________________ 
    
     was added at a constant rate over a period of 31/2 hours to a refluxing and agitated mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    500 partsCellosolve               100 partsButyl cellosolve         100 parts______________________________________ 
    
     Refluxing was continued for 1/2 hour after the addition was completed and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTertiary butyl perbenzoate                     5 parts______________________________________ 
    
     was added over a 15 minute period and then reflux and agitation were continued for two hours. The finished resin solution had a viscosity of K (Gardner Holt) at 52.7% solids and an acid value of 12.6 based on non-volatiles. The polymer solution was used as stabilizer for preparing dispersion polymer compositions. 
     A dispersion polymer composition was made by adding a monomer mixture of 
     
         ______________________________________Methyl methacrylate      342 partsStyrene                  190 partsHydroxypropyl methacrylate                     95 partsAcrylic acid              5 partsAliphatic hydrocarbon (as above)                     50 partsTertiary butyl perbenzoate                     18 parts______________________________________ 
    
     to a refluxing and strongly agitated mixture of 
     
         ______________________________________Stabilizer polymer solution (as above)                     400 partsAliphatic hydrocarbon (as above)                     300 parts______________________________________ 
    
     over a period of 31/2 hours. Refluxing and agitation were continued for 30 minutes and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    49 partsTertiary butyl perbenzoate                    11 parts______________________________________ 
    
     was added over a period of 15 minutes. Two hours after this addition was complete the reaction mixture was reduced with 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    100 partsn-Butanol                 85 partsMonobutyl ether of ethylene glycol                     55 parts______________________________________ 
    
     over a period of 15 minutes. The batch was then cooled to 50° C. and poured through a fine strainer. Strong agitation was maintained from the start of the addition of the monomer mixture until the time of pouring. Reflux was maintained continuously until the reduction with solvent. The resulting dispersion polymer composition was smooth and non-settling. The dispersion polymer composition is useful as a non-aqueous dispersion in the formulation of a paint similar to that in Example 1. 
     EXAMPLE 4 
     A dispersion polymer composition was made by the procedure of Example 3, except that 3 hours instead of 31/2 hours were used to add a monomer mixture consisting of 
     
         ______________________________________Methyl methacrylate       320 partsStyrene                   180 partsHydroxyethyl acrylate      95 partsMethacrylic acid           5 partsAliphatic hydrocarbon (as in Example 1)                      83 partsTertiary butyl perbenzoate                      17 parts______________________________________ 
    
     to a stabilizer polymer solution consisting of 
     
         ______________________________________Stabilizer polymer solution of Example 3)                     380 partsAliphatic hydrocarbon (as above)                     270 parts______________________________________ 
    
     and adding further catalyst mixture consisting of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTertiary butyl perbenzoate                    10 parts______________________________________ 
    
     and reducing with 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    70 partsn-Butanol                60 partsMonobutyl ether of ethylene glycol                    60 parts______________________________________ 
    
     The resulting dispersion polymer composition was smooth and non-settling, had a viscosity of 42 seconds (#4 Ford Cup) at 74° F. and 51.4% solids. The resin had an acid number of 10.3 based on solids. The stabilizer polymer component was 25% by weight of the total solids. The dispersion was used to formulate a paint as in Example 1 consisting of 
     
         ______________________________________Dispersion polymer composition                   43 partsThermosetting acrylic resin solution                   47 parts(50% solids solution of a copolymerof 48% butyl methacrylate, 35% styrene,15% hydroxyethyl methacrylate and 2%methacrylic acid in a mixture of 60parts n-butyl acetate and 40 partscellosolve acetate)Melamine resin solution 37 parts(60% solids butylated melamine-formaldehyde in a mixture of 87 partsn-butanol and 13 parts aliphaticnaphtha)Titanium dioide paste   34 parts(59.9% pigment, 14.6% soluble thermo-setting acrylic resin and 25.5% solventconsisting of 67.8 parts xylene, 19.7parts high flash aromatic naphtha,7.6 parts n-butanol, and 4.9 partscellosolve acetate)Phthalocyanine blue paste                    4 parts(7.6% pigment, 33.9% soluble thermo-setting acrylic resin and 58.5% solventconsisting of a mixture of 73.4 partsxylene, 18.8 parts cellosolve acetateand 7.8 parts aromatic naphtha)Ethyl acetate (88%)     42 partsCellosolve acetate      26 partsToluene                 11 partsAromatic naphtha         6 partsTotal                   250 parts______________________________________ 
    
     The paint solids consist of 22% pigment and 78% binder and at spray viscosity of 15.5 seconds at 74° F. (#4 Ford Cup) the paint has a solids content of 37.9%. The binder component of the paint consists of 22.5% dispersed polymer, 30% melamine resin and 47.5% soluble thermosetting acrylic resin. When sprayed out and baked 30 minutes at 250° F., the baked film had a 20° gloss of 81 at 2.3 mils thickness. 
     The thermosetting acrylic resin used in the titanium dioxide paste was a copolymer of 48% butyl methacrylate, 30.5% styrene, 20% hydroxy ethyl methacrylate and 1.5% methacrylic acid. 
     The thermosetting acrylic resin used in the phthalocyanine blue paste was a copolymer of 31.5% styrene, 31% hydroxypropyl methacrylate, 21% butyl acrylate, and 16.5% methyl methacrylate. 
     EXAMPLE 5 
     A dispersion polymer composition was made by the procedure of Example 4 by adding a monomer mixture containing 
     
         ______________________________________Methyl methacrylate      300     partsStyrene                  160     partsHydroxyethyl methacrylate                    95      partsAcrylic acid             5       partsAliphatic hydrocarbon (as in Example 1)                    94      partsTertiary butyl perbenzoate                    16      parts______________________________________ 
    
     to a stabilizer polymer solution consisting of 
     
         ______________________________________Stabilizer polymer solution ofExample 3                455 partsAliphatic hydrocarbon (as above)                    245 parts______________________________________ 
    
     and adding further catalyst mixture consisting of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTertiary butyl perbenzoate                    10 parts______________________________________ 
    
     and reducing with 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsn-Butanol                60 partsMonobutyl ether of ethylene glycol                    60 parts______________________________________ 
    
     The resulting dispersion polymer composition was smooth and non-settling and had other properties similar to the dispersion polymer compositions of Examples 3 and 4. It contains 30% stabilizer polymer, based on total solids, while the dispersion polymer compositions of Examples 3 and 4 both contain 25% stabilizer polymer, on a solids basis. 
     EXAMPLE 6 
     A stabilizer polymer solution was prepared by the procedure of Example 3 by adding a mixture of 
     
         ______________________________________Lauryl methacrylate      395 parts2 - Ethyl hexyl methacrylate                    390 partsHydroxypropyl methacrylate                    200 partsAcrylic acid              15 partsAliphatic hydrocarbon (as in Example 1)                    100 partsTertiary butyl perbenzoate                     15 parts______________________________________ 
    
     to a refluxing and agitated mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    500 partsMonoethyl ether of ethylene glycol                    100 partsMonobutyl ether of ethylene glycol                    100 parts______________________________________ 
    
     The addition was made at a constant rate over a period of 31/2 hours. Refluxing and agitation were continued for 30 minutes after the monomer addition was completed and then a mixture of 
     
         ______________________________________Aliphatic hydrocarbon (as above)                    50 partsTertiary butyl perbenzoate                     5 parts______________________________________ 
    
     was added over a 15 minute period and then refluxing and agitation were continued for 2 hours. Finally the batch was reduced to viscosity F at 47.5% solids with 130 parts of Espesol 260° F. (aliphatic hydrocarbon B.P. about 130° C.). The stabilizer polymer solution had an acid value of 16.4 based on solids. 
     A dispersion polymer composition was prepared by adding a monomer solution containing 
     
         ______________________________________Methyl methacrylate      274 partsStyrene                  172 partsHydroxypropyl methacrylate                    115 partsAcrylic Acid              13 partsEspesol 260F             100 partsTertiary butyl perbenzoate                     16 parts______________________________________ 
    
     to a refluxing and strongly agitated mixture of 
     
         ______________________________________Stabilizer polymer solution                    500 parts47.5% solidsEspesol 260F             200 parts______________________________________ 
    
     The addition was made at a constant rate over a period of 31/2 hours and gentle refluxing was continued for 30 minutes after the addition was completed and then additional catalyst solution consisting of 
     
         ______________________________________Tertiary butyl perbenzoate              10 partsEspesol 260 F      50 parts______________________________________ 
    
     was added over a period of 30 minutes and refluxing and agitation were continued for 2 hours. Finally the batch was reduced with 
     
         ______________________________________Espesol 260 F     50 partsn-Butanol         85 partsButyl cellosolve  55 parts______________________________________ 
    
     to a solids content of 52% and viscosity of 65 seconds (#4 Ford Cup) at 73° F. The dispersion had an acid number of 18.6 based on solids and showed no settling after 3 days storage. The dispersion was used to prepare a paint consisting of 
     
         ______________________________________Dispersion polymer composition                    200 parts52% solidsPigment dispersion       40 partsMelamine resin           78 partsSolvents                 92 parts______________________________________ 
    
     The paint had a spray viscosity of 18 seconds (#4 Ford Cup) at 73° F., a non-volatile content of 39.5% (38% resin + 1.5% pigment), a pigment/binder ratio of 3.9/100 and baked films of the paint, baked 30 minutes at 250° F., had a 20° gloss of 67 at 2.0 mils thickness. 
     The binder resin component in the above paint consists of 46% dispersed resin (from the dispersion polymer composition), 29.4% melamine resin and 24.6% soluble thermosetting acrylic resin (including the stabilizer polymer and the pigment dispersion resin). The pigment consists of 65% aluminum pigment and 35% Quinacridone Magenta Toner. The solvents consist of 61.6% aliphatic naphthas (Espesol 260° F and Soltrol 50), 21.5% alcohols (n-butanol, 2-ethyl hexanol, isopropanol), 9.3% monobutyl and monoethyl ethers of ethylene glycol, 4.1% Xylene and aromatic naphtha and 3.5% monobutyl ether of ethylene glycol acetate. The pigment dispersion resin is the same as that described in Example 1 - pigment dispersion. 
     EXAMPLE 7 
     In a manner similar to Example 3, a stabilizer polymer solution at 48.7% solids was made from 
     
         ______________________________________Lauryl methacrylate      440 parts2 - Ethyl-hexyl methacrylate                    200 partsStyrene                  150 partsHydroxypropyl methacrylate                    200 partsAcrylic acid              10 partsEspesol 260F             185 partsCellosolve               100 partsButyl cellosolve         100 parts______________________________________ 
    
     The 48.7% solids solution had viscosity of 0 at 25° C. and an acid number of 12.3 based on solids. 
     A dispersed polymer was formed in a solution of the stabilizer in a manner similar to Example 3 from a solution of a mixture of monomers and catalyst consisting of 
     
         ______________________________________Methyl methacrylate      316     partsStyrene                  176     partsHydroxypropyl methacrylate                    88      partsAcrylic acid             5       partsEspesol 260F             98      partsTertiary butyl perbenzoate                    17      parts______________________________________ 
    
     a stabilizer polymer solution consisting of 
     
         ______________________________________Stabilizer polymer solutionfrom above (48.7% solids)                    500 partsEspesol 260F             200 parts______________________________________ 
    
     an additional catalyst solution consisting of 
     
         ______________________________________Espersol 260F      50 partsTertiary butyl perbenzoate              10 parts______________________________________ 
    
     and a reducing solvent mixture of 
     
         ______________________________________Espersol 260F            70 partsn-Butanol                85 partsMonobutyl ether of ethylene glycol                    55 parts______________________________________ 
    
     This dispersion polymer composition had a viscosity of 61 seconds at 71° F. (#4 Ford Cup), 50.5% solids, and an acid number of 12.1 based on solids. The dispersion was smooth, non-settling and useful for preparing paints in accordance with the invention. 
     EXAMPLE 8 
     Using the stabilizer polymer solution of Example 7, a dispersion polymer composition was formed in a manner similar to Example 4 from a solution of a mixture of monomers and catalyst consisting of 
     
         ______________________________________Methyl methacrylate      317 partsVinyl toluene            146 partsHydroxypropyl methacrylate                    117 partsAcrylic acid              5 partsEspesol 260F              59 partsTertiary butyl perbenzoate                     16 parts______________________________________ 
    
     a stabilizer polymer solution consisting of 
     
         ______________________________________Stabilizer polymer solutionof Example 7             500 partsEspesol 260F             250 parts______________________________________ 
    
     an additional catalyst solution consisting of 
     
         ______________________________________Espesol 260F       50 partsTertiary butyl perbenzoate              10 parts______________________________________ 
    
     and a reducing solvent mixture of 
     
         ______________________________________Espesol 260F             60 partsn-Butanol                60 partsMonobutyl ether of ethylene glycol                    60 parts______________________________________ 
    
     This dispersion polymer composition was smooth and non-settling, had a non-volatile content of 51.6%, and acid number of 11.2 based on solids, and a #4 Ford Cup viscosity of 55 seconds at 72° F. It was used to prepare a sprayable paint of the following composition. 
     
         ______________________________________Dispersion polymer composition(at 51.6% N.V.)          84 partsThermosetting acrylic resin solution(at 50% N.V.) as in Example 4                    43 partsMelamine resin solution(at 60% N.V.)            70 partsBlack pigment paste(3.7% pigment, 30.6% binder resin)                    67 partsReducing solvents        130  parts______________________________________ 
    
     The binder in the black pigment paste is a soluble thermosetting acrylic resin similar to that used in the blue paste of Example 4, and the pigment to total binder ratio in the paint is 1/51. The binder consists of about 24% dispersed polymer, 43% soluble thermosetting acrylic polymer (including stabilizer polymer and binder in the pigment paste), and 33% melamine resin. The overall solvent composition is about 51% esters (ethyl acetate, cellosolve acetate, butyl cellosolve acetate and butyl acetate), 22% aromatic hydrocarbon (xylene, toluene and aromatic naphtha), 14% aliphatic naphthas, 11% butanol, and 2% cellosolve and butyl cellosolve. The paint at 33% solids (0.64% pigment, 32.36% binder resin) had a spray viscosity of 151/2 seconds at 74° F. (#4 Ford Cup). A spray out of the paint on a primed steel panel and baked 30 minutes at 250° F. had a 20° gloss of 80 at 1.9 mils thickness. The baked film had good mar resistance, humidity resistance and acid spotting resistance. 
     EXAMPLE 9 
     A stabilizer polymer solution was prepared by adding a solution of monomers and catalyst consisting of 
     
         ______________________________________Lauryl methacrylate      460 partsButyl methacrylate       230 partsStyrene                  150 partsHydroxypropyl methacrylate                    150 partsAcrylic acid              10 partsEspesol 260F              40 partsTertiary butyl perbenzoate                     8 parts______________________________________ 
    
     to 600 parts of refluxing and agitated Espesol 260 over a period of two hours. Immediately upon completion of the addition of the monomer and catalyst solution an additional catalyst solution, consisting of 7 parts tertiary butyl perbenzoate and 145 parts of Espesol 260F, was added to the reaction mixture over a period of 2 hours and heating and refluxing were continued for 3 hours. The mixture was then reduced with 200 parts Espesol 260F and cooled. The resin solution had a solids content of 49.3%, an acid number of 9.8 based on solids, and a Gardner Holt viscosity of z3 - z4 at 25° C. 
     Three different dispersion polymer compositions were prepared using the above stabilizer polymer as follows: 
     
         ______________________________________              Dispersions              (Parts)Part A               #1      #2      #3______________________________________Stabilizer polymer solution,at 49.3% solids      500     500     400Espesol 260F         200     200     300Part BMethyl methacrylate  137     137     219n-Butyl methacrylate 137     --      --n-Butyl acrylate     --      137     --Styrene              172     172     137Hydroxypropyl methacrylate                115     115      92Acrylic acid          10      10      8Espesol 260F         113     113     221t-Butyl perbenzoate   16      16      13Part CEspesol 260F          50      50      50t-Butyl perbenzoate   10      10      10Part DEspesol 260F         340     220     190n-Butanol             50      60     --Butyl cellosolve      50      60     --______________________________________ 
    
     The same cooking procedure was used for each of the three dispersions and consisted of adding Part B to the strongly agitated and refluxing Part A over a period of three hours, refluxing for an additional 1/2 hour, adding Part C over a period of 15 minutes, refluxing and agitating for 2 hours, adding Part D over a period of 15 minutes, and cooling. 
     Dispersion 1 had a No. 4 Ford Cup viscosity of 58 seconds at 77° F., a solids content of 46.3%, and an acid number of 13.5 based on solids. The dispersion was used to formulate two light blue paints similar to that of Example 4 at 15% and 25.5% pigment. The paints gave good results similar to those of Example 4 with baked films having a gloss of over 80. The paints have good stability in that they showed substantially no settling at spray viscosity. 
     Dispersion 2 had a viscosity of 315 seconds (No. 4 Ford Cup) at 80° F., a solids content of 47.7% and an acid number of 14.1 based on solids. A light blue paint similar to that of Example 4 was made from the dispersion wherein the solids content of the paint consisted of 19% pigment and 81% binder resin, the binder in this case consisting of 28% dispersed thermosetting acrylic resin, 30% melamine resin and 42% soluble thermosetting acrylic resins. At 37.2% solids, the paint had a viscosity of 151/2 seconds (No. 4 Ford Cup) at 74° F., and a spray out baked 30 minutes at 250° F. had a 20° gloss of 72 at 2.2 mils film thickness. The baked film had satisfactory hardness and gloss for use as a topcoat automobile finish. 
     Dispersion 3, at 40.7% solids, was too thixotropic for viscosity determination by Ford Cup but it was fairly fluid when stirred and had satisfactory working properties. The acid number was 14.1 based on solids. A paint was fomulated consisting of: 
     
         ______________________________________Dispersion 3, at 40.7 N.V.                    54 partsSoluble thermosetting acrylic resinsolution (50% N.V.) same as inExample 4                47 partsMelamine resin solution(Same as in Example 4)   67 partsTitanium dioxide paste(Same as in Example 4)   34 partsEthyl acetate            37 partsCellosolve acetate       23 partsToluene                  10 partsAromatic naphtha          5 parts______________________________________ 
    
     This paint at 37.8% solids (22% pigment, 78% binder) had a viscosity of 151/2 seconds (No. 4 Ford Cup) at 74° F. A sprayed film on primed steel was baked 30 minutes at 250° F. and had a 20° gloss of 72 at 1.9 mils film thickness. The solvents in the paint consist of 32.6% alkyl esters (ethyl acetate and butyl acetate), 21.3% of the acetate esters of cellosolve and butyl cellosolve, 21.7% aliphatic naphthas (Espesol 260F and Soltrol 50), 15.7% aromatic hydrocarbons and 8.7% n-butanol. 
     EXAMPLE 10 
     A stabilizer polymer solution was prepared by adding Mixture B over a period of 3.5 hours to agitated and refluxing (132° C.) Mixture A and refluxing was continued for 0.5 hour. Then Mixture C was rapidly added and refluxing continued for two hours. Finally 120 parts of Espesol 260F was added and the batch was cooled. 
     
         ______________________________________Mixture AEspesol 260F         300 partsButyl cellosolve     250 partsCellosolve           125 partsMixture BLauryl methacrylate  389 partsStyrene              389 partsHydroxypropyl methacrylate                198 partsAcrylic acid          14 partsEspesol 260F         100 partst-Butyl perbenzoate   25 partsCellosolve            25 partsMixture CEspesol 260F          50 partst-Butyl perbenzoate   5 parts______________________________________ 
    
     The resulting resin solution had a viscosity of T+ (Gardner-Holt) at 25° C., a solids content of 52% and an acid number of 14.5 based on solids. 
     The stabilizer polymer solution prepared above was used to prepare a dispersion polymer composition by adding Mixture B (below) over a 3.5 hour period to refluxing (128° C.) Mixture A (below), refluxing an additional 30 minutes before adding Mixture C over a period of 30 minutes and then refluxing another 2 hours. Finally, the batch was reduced with Mixture D and the reaction mixture was cooled. Strong agitation was used throughout the cook. 
     
         ______________________________________Mixture AStabilizer polymer solution, 52% solids                    500 partsEspesol 260F             200 partsMixture BMethyl methacrylate      250 partsButyl methacrylate        50 partsStyrene                  146 partsHydroxypropyl methacrylate                    115 partsAcrylic acid              13 partsEspesol 260F             110 partst-Butyl perbenzoate       16 partsMixtue CEspesol 260F              50 partst-Butyl perbenzoate       10 partsMixture DEspesol 260F             290 partsButyl cellosolve         100 partsButanol                   50 parts______________________________________ 
    
     The resulting polymer dispersion had a solids content of 45.3%, an acid number of 19.9 based on solids, and a No. 4 Ford Cup viscosity of 20 seconds at 90° F. 
     A paint was prepared from the above dispersed polymer composition consisting of: 
     
         ______________________________________Dispersed polymer composition(45.3% Solids)          250 partsPigment Dispersion (15.5% pigment,22.8% binder as in Example 1)                   45 partsMelamine Resin (60% solids)                   88 partsEspesol 260F            55 parts2-Ethyl hexyl alcohol   13 parts______________________________________ 
    
     The paint had a No. 4 Ford Cup viscosity of 17 seconds at 25° C., and a calculated solids of 40.7% (1.56% pigment, 39.14% binder resin). The binder consists of 44% dispersed polymer, 30% melamine resin and 26% soluble thermosetting acrylic resin (stabilizer polymer plug pigment dispersion resin). The pigment consists of 65% aluminum pigment and 35% Quinacridone Magenta Toner. The overall solvent composition was about 62% aliphatic naphthas (Espesol 260F and Soltrol 50), 16% n-Butanol, 5% 2-ethyl hexanol, 10% monobutyl and monoethyl ethers of ethylene glycol, 3% acetate ester of monobutyl ether of ethylene glycol, and 4% aromatic hydrocarbon. A spray-out on a primed steel panel, baked 30 minutes at 250° F. had a 20° gloss of 70 at 1.7 mils thickness. 
     EXAMPLE 11 
     An automotive paint prepared in accordance with the invention consists of: 
     
         ______________________________________Resin solution A (see below)                   226 partsButylated melamine-formaldehyde resin,as a 65% solution in a mixture of 65parts butyl acetate and 35 parts butylalcohol                 148 partsEthyl acetate           81 partsCellosolve acetate      63 partsToluene                 23 partsSolvesso 100 (aromatic hydrocarbon,B.P. 160-177° C.)                   12 partsAluminum pigment, 60% metal in40% hydrocarbon solvent(Silberline L-582)      10 partsAluminum pigment, 65% metal in35% hydrocarbon solvent(Alcan MD 637)           2 partsPhthalocyanine Blue PigmentDispersion (see below)  42 partsQuinacridone Magenta PigmentDispersion (see below)   6 partsDispersed polymer composition(see below)             187 parts______________________________________ 
    
     and has a non-volatile content of 41.18% (1.38% pigment, 39.80% binder resins) and a viscosity of 22 seconds (Ford #4 Cup) at 25° C. The paint is reduced to a spray viscosity of 15 seconds (Ford #4 Cup) with a mixture of VM&amp;P Naphtha 66%, butyl cellosolve acetate 20% and toluene 14% and applied at 2 mils dry film thickness on sheet steel primed with a commercial electrodeposited primer. The paint film, cured 30 minutes at 250° F., had a gloss of 72° minimum using a 20° glossmeter, a hardness of 10 Knoop units, better overbake intercoat adhesion than competitive commercial NAD type topcoats. In other properties such as cold crack resistance, humidity resistance, reflow, color drift, film build, oven stability and acid spotting resistance, the paint was equal or better than competitive commercial NAD type topcoats. 
     Resin Solution A is a thermosetting acrylic (TSA) copolymer of 23.57 parts butyl methacrylate, 17.51 parts styrene, 7.5 parts hydroxyethyl methacrylate (94% grade), and 1 part glacial methacrylic acid, prepared in 20.01 parts cellosolve acetate and 30.02 parts n-butyl acetate using 0.39 parts di-tertiary butyl peroxide as catalyst. Total non-volatile content is 49.58% assuming 100 percent conversion of monomers. 
     Dispersed Polymer Composition (NAD) is a dispersion of a thermosetting acrylic copolymer of 167 parts methyl methacrylate, 103 parts styrene, 69.7 parts hydroxypropyl methacrylate and 3 parts glacial acrylic acid prepared in 303 parts of a 50% solution of a stabilizer polymer prepared from lauryl methacrylate, butyl methacrylate, styrene, hydroxypropyl methacrylate and acrylic acid in the ratios 32/32/15/20/1, respectively, and enough solvent to equal 1000 parts. Total non-volatile of the dispersion was 51% (approximately 16% stabilizer and 35% dispersed polymer). The solvents in the 303 parts of stabilizer polymer solution is a mixture consisting of 55% High Flash VM&amp;P Naphtha, 30% VM&amp;P Naphtha, and 15% butyl cellosolve. Additional solvents added in the preparation of the dispersed polymer consisted of a mixture whose composition was approximately 36% VM&amp;P Naphtha, 46% High Flash VM&amp;P Naphtha and 18% n-butanol. 
     Phthalocyanine Blue Pigment Dispersion is a dispersion of 7.61% phthalocyanine blue pigment in 33.93% vehicle (approximately 50% solution of a thermosetting copolymer of 48.0% butyl methacrylate, 30.5% styrene, 20% hydroxyethyl methacrylate, 94% grade, and 1.5% glacial methacrylic acid, in a mixture of 90 parts xylol and 10% butyl alcohol) and 58.46% of a hydrocarbon solvent consisting of 30--70 mixture of VM&amp;P Naphtha-Xylol. 
     Quinacridone Magenta Pigment Dispersion is a dispersion of 8.31% pigment in 30.36% vehicle (same as in the phthalocyanine blue dispersion) and 61.33% of hydrocarbon solvent (same as in the phthalocyanine blue dispersion). 
     EXAMPLE 12 
     A low-bake repair paint is prepared by adding 4% by volume of acid catalyst solution (41.65% maleic anhydride, 58.35% butyl alcohol) to the paint of Example 11. The repair paint cures at 180° F. in 20 minutes. 
     The properties of the baked repair finish are equal or better, in all properties tested, than competitive commercial TSA and NAD type topcoats. 
     EXAMPLE 13 
     A stabilizer polymer solution was prepared by adding a solution of monomers and catalyst consisting of 
     
         ______________________________________2-Ethyl hexyl methacrylate                320 partsButyl methacrylate   320 partsStyrene              150 partsHydroxypropyl methacrylate                200 partsAcrylic acid          10 partsHigh Flash VM&amp;P Naphtha                 50 partsTert. butyl perbenzoate                 14 parts______________________________________ 
    
     to a refluxing (130° - 132° C.) mixture of 
     
         ______________________________________VM&amp;P Naphtha         300 partsHigh Flash VM&amp;P Naphtha                250 partsButyl cellosolve      75 partsCellosolve acetate    75 parts______________________________________ 
    
     over a period of 3 hours and refluxing was continued for 1 hour. Then a mixture of 
     
         ______________________________________High Flash VM&amp;P Naphtha                  50 partsTert. butyl perbenzoate                   7 parts______________________________________ 
    
     was added over a period of 1/4 hour and refluxing was continued for 3 hours. Finally, the resulting resin solution was reduced to 50% non-volatiles with High Flash VM&amp;P Naphtha. The stabilizer resin solution had a Gardner Holt viscosity of X+ at 49.9% non-volatiles and an acid number of 11.0 based on non-volatiles. 
     A dispersion resin composition was prepared by adding a solution of monomers and catalyst consisting of 
     
         ______________________________________Methyl methacrylate    286 partsStyrene                176 parts2-Hydroxyethyl acrylate                   97 partsMethacrylic Acid        6 partsHigh Flash VM&amp;P Naphtha                  100 partsTert. butyl perbenzoate                   16 parts______________________________________ 
    
     to a refluxing solution consisting of 
     
         ______________________________________Stabilizer polymer solution (above)                   500 partsHigh Flash VM&amp;P Naphtha 160 partsVM&amp;P Naphtha             40 parts______________________________________ 
    
     over a period of three hours and refluxing was continued for 1/2 hour. Then catalyst solution consisting of 
     
         ______________________________________VM&amp;P Naphtha           50 partsTert. butyl perbenzoate                   8 parts______________________________________ 
    
     was added over a period of 1/4 hour and refluxing was continued for 2 hours. The resulting dispersion polymer composition, after reduction with 
     
         ______________________________________VM&amp;P Naphtha         111 partsn-Butanol            100 parts______________________________________ 
    
     had viscosity of 100 seconds (No. 4 Ford Cup) at 72° F. and 51.1% solids. It had an acid number of 10.9 based on solids. The dispersion was smooth and non-settling overnight, but developed some soft settling in 4 days. Paints made with the dispersion in accordance with the invention were similar to those of the above examples. 
     EXAMPLE 14 
     A stabilizer polymer solution was prepared by adding a solution of monomers and catalyst consisting of 
     
         ______________________________________2-Ethyl hexyl acrylate 500 partsStyrene                120 partsHydroxy propyl methacrylate                  160 partsAcrylic acid            10 partsTert. butyl perbenzoate                   10 parts______________________________________ 
    
     to a refluxing (129° C.) mixture of 
     
         ______________________________________High Flash VM&amp;P Naphtha                400 partsVM&amp;P Naphtha          50 partsHeptane              100 parts______________________________________ 
    
     over a period of 2 hours and then the mixture was refluxed for another hour. A solution of catalyst consisting of 
     
         ______________________________________High Flash VM&amp;P Naphtha  50 partsTert. butyl perbenzoate   5 parts______________________________________ 
    
     was then added over 1/4 hour and then the mixture was refluxed for 3 hours while additional solvent was added consisting of 
     
         ______________________________________Butyl cellosolve      50 partsToluene               50 partsHigh Flash VM&amp;P Naphtha                 50 partsCellosolve acetate    50 parts______________________________________ 
    
     to obtain a stabilizer polymer solution having a Gardner Holt viscosity of H at 49.5% solids and 25° C., and an acid number of 12.5 based on solids. 
     A dispersion polymer composition was made in a manner similar to the above examples by copolymerizing a solution of monomers consisting of 
     
         ______________________________________Methyl methacrylate 274 partsStyrene             172 partsHydroxy propyl methacrylate               115 partsAcrylic acid         10 partsHigh Flash VM&amp;P Naphtha               150 partsVM&amp;P Naphtha         50 parts______________________________________ 
    
     in the presence of a solution of the above stabilizer polymer consisting of 
     
         ______________________________________Stabilizer polymer solution (above)                     500 partsHigh Flash VM&amp;P Naphtha   150 parts______________________________________ 
    
     using 30 parts of tert. butyl perbenzoate catalyst. After further reduction with 
     
         ______________________________________VM&amp;P Naphtha          80 partsn-Butanol             60 partsButyl cellosolve      60 parts______________________________________ 
    
     the dispersion polymer composition had a solids content of 51.2%, a viscosity of 54 seconds (No. 4 Ford Cup) at 66° F. and an acid number of 15.3 based on solids. The dispersion was smooth and showed only slight, medium soft settling in three days. Paints made with the dispersion were similar to those of the above examples.