Coating composition comprising a methyl methacrylate polymer and a cellulose ester and process for preparing same

Claim 1

A PIGMENTED COATING COMPOSITION, WHICH PRODUCES A DRY COATING CHARACTERIZED BY UNIFORM PIGMENT DISPERSION AND BY THE ABSENCE OF PIGMENT FLOODING AND MOTTLING, COMPRISING A POLYMER OF METHYL METHACRLLATE AS THE PREPONDERANT FILM-FORMING MATERIAL, VOLATILE SOLVENT THEREFOR, PLASTICIZER THEREFOR, PIGMENT AND ABOUT 0.1-10%, BY WEIGHT, BASED ON THE TOTAQL WEIGHT OF NON-VOLATILE CONSTITUENTS IN SAID COATING COMPOSITION, OF A CELLULOSE ESTER SELECTED FROM THE GROUP CONSISTING OF CELLULOSE NITRATE, CELLULOSE PROPIONATE, CELLULOSE BUTYRATE, CELLULOSE ACERTATE BUTYRATE, CELLULOSE ACETATE PROIONATE, AND MIXTURES THEREOF, SAID POLYMER OF METHYL METHACRYLATE BEING AT LEAST ONE MATERIAL OF THE GROUP CONSISTING OF MOMOPOLYMERS OF METHYL METHACRYLATE AND COPOLYMERS OF METHYL METHACRYLATE WITH FROM 2 TO 2K% BY WEIGHT OF A MEMBER OF THE GROUP CONSISTING OF ACRYLIC ACID, METHACRYLIC ACID, A 1 TO 4 CARBON ALKYL ESTER OF ACRYLIC ACID, A 2 TO 4 CARBON ALKYL ESTER OF METHACRYLIC ACID, VINLY ACETATE, ACRYLONITRILE AND STYRENE; AND SAID POLYMER OF METHYL METHACRYLATE BEING FURTHER CHARACTERIZED BY HAVING A RELATIVE VISCOSITY OF ABOUT 1.117 TO 1.196, SAID RELATIVE VISCOSITY BEING THE QUOTIENT OBTAINED BY DIVIDING THE EFFLUX TIME OF A SOLUTION OF 0.25 GRAM OF SAID METHYL METHACRYLATE COMPONENT IN 50 CC. OF ETHYLENE DICHLORIDE BY THE EFFLUX TIME OF ETHYLENE DICHLORIDE, SAID EFFLUX TIME BEING MEASURED IN ACCORDANCE WITH THE PROCEDURE OF ASTM D-445-46T, METHOD B, AT 25*C. USING A MODIFIED OSTOWALD VISCOSIMETER, SERIES 50.