Patent GB-973889-A (GB)
Title: Improvements in or relating to coating compositions
IPC: D06N3/04
Filed: 1961-02-22
Abstract: A composition suitable for forming a flexible self-supporting film by extrusion whilst molten comprises a blend of (A) cellulose acetate-butyrate having a viscosity of 0.1-20 secs. as determined by ASTM method D1343-56 and (B) an acrylic ester copolymer consisting essentially of (i) recurring units of the formula:- <FORM:0973889/C3/1> and (ii) recurring units of the formula:- <FORM:0973889/C3/2> where R represents a C1-C4 alkyl group, said copolymer having a viscosity average molecular weight of 180,000 to 800,000 and an apparent second order transition temperature Ti between 27 DEG  and 47 DEG C., the cellulose acetate-butyrate in the blend being present in a minor proportion sufficient to reduce the self-blocking tendency of the film formed by extrusion of the composition whilst molten.  Small amounts e.g. up to 5% of other copolymerizable monoethylenically unsaturated comonomers may also be present e.g. acrylic acid, methacrylic acid, acrylamide, itaconic acid, vinyl acetate, acrylonitrile, vinyltoluene, vinyl chloride and/or vinylidene chloride.  The blend may also include 1-50% of pigment, 0.1-1% of dye, 2-20% of plasticizer and 0.01-2% of ultra-violet light stabilizer e.g. phenyl salicylate and a small amount of a lubricant e.g. stearic acid.  Preferred copolymers have a viscosity average molecular weight of 270,000-350,000, and may be copolymers of (i) methyl, ethyl or butyl acrylate or mixtures thereof and (ii) methyl, ethyl or butyl methacrylate or mixtures thereof, or may consist essentially or exclusively of polymerized methyl methacrylate and ethyl acrylate units e.g. 40-55% by weight methyl methacrylate and 60-45% by weight ethyl acrylate.  From 3-20% by weight of cellulose acetate-butyrate, based on the copolymer, may be present in the blend, preferably at least 10%.  Sufficient cellulose acetate-butyrate may be present to render a film made from the composition resistant to self-blocking at 140 DEG F. and 75% relative humidity at a pressure of 2 3/4 lb. per sq. inch.  Films may be made by melt-extrusion of the composition and applied while hot to various substrates to form laminates.  For details see Division B2.  U.S.A. Specifications 2,169,554, 2,211,689 and 2,764,509 are referred to.ALSO:Substrates of paper, leather, textile fabrics including woven cloth and non-woven fleece or web, wood, flexible pellicles of plastic material, tinfoil, aluminium foil, building board, e.g. gypsum board, pressed fiber board, or aluminium siding, are coated with a hot melt-extruded film of a composition comprising a blend of (A) cellulose acetate-butyrate having a viscosity of 0,1-20 secs. as determined by ASTM method D1343-56 and (B) an acrylic ester copolymer consisting essentially of (i) recurring units of the formula: <FORM:0973889/B1-B2/1> and (ii) recurring units of the formula: <FORM:0973889/B1-B2/2> where R represents a C1-C4 alkyl group, said copolymer having a viscosity average molecular weight of 180,000-800,000 and an apparent second order transition temperature T1 between 27 and 47  DEG C., the cellulose acetate-butyrate in the blend being present in a minor proportion sufficient to reduce the self-blocking tendency of the film formed p  by extrusion of the composition whilst molten.  Small amounts, e.g. up to 5% of other copolymerizable monoethylenically unsaturated comonomers may also be present, e.g. acrylic acid, methacrylic acid, acrylamide, itaconic acid, vinyl acetate, acrylonitrile, vinyltoluene, vinyl chloride and/or vinylidene chloride.  The blend may also include 1-50% of pigment, 0,1-1% of dye, 2-20% of plasticizer and 0,01-2% of ultra-violet light stabilizer, e.g. pheyl salicylate and a small amount of a lubricant, e.g. stearic acid.  Preferred copolymers have a viscosity average molecular weight of 270,000-350,000, and may be copolymers of (i) methyl, ethyl or butyl acrylate or mixtures thereof and (ii) methyl, ethyl or butyl methacrylate or mixtures thereof, or may consist essentially or exclusively of polymerized methyl methacrylate and ethyl acrylate units, e.g. 40-55% by weight methyl methacrylate and 60-45% by weight ethyl acrylate. From 3-20% by weight of cellulose acetate-butyrate, based on the copolymer, may be present in the blend, preferably at least 10%. Sufficient cellulose acetate-butyrate may be present to render a film made from the composition resistant to self-blocking at 140  DEG F. and 75% relative humidity at a pressure of 2 3/4 lbs. per sq. inch.  One or both surfaces of the substrate may be coated, to provide a greaseproof, waterproof and oil-resistant coating. U.S.A. Specifications 2,169,558, 2,211,689 and 2,764,509 are referred to.