Patent GB-853885-A (GB)
Title: Improvements relating to finishing systems for coated articles
Inventor: BLAKE JULES
IPC: C09D133/12
Filed: 1958-09-18
Abstract: Coating compositions comprise at least one polymer of methyl methacrylate containing in the polymer chain units of formula: <FORM:0853885/IV(a)/1> where one R is a hydroxyl group or a negatively charged oxygen atom and the other R is an amino group bonded through amino nitrogen, the said units, exclusive of the amino groups, constituting 0,2 to 20% of the total weight of methyl methacrylate polymer in the composition.  The polymers may be prepared by copolymerizing methyl methacrylate and glycidyl methacrylate, optionally together with minor amounts of copolymerizable monomers, e.g. acrylic acid; methacrylic acid; methyl, ethyl, propyl and butyl acrylates; ethyl, propyl, butyl and lauryl methacrylates; vinyl acetate; acrylonitrile and styrene, in solution in isopropyl alcohol and toluene in the presence of benzoyl peroxide, and reacting the copolymer with ammonia or monoamines, e.g. t-butyl-amine, ethanolamine, ethylamine, t-octylamine, dimethylamine, diethanolamine, methylethylamine, dimethylbenzylamine, N-methyl-morpholine, dimethyl-palmitylamine and triethanolamine, preferably in the presence of volatile solvents, e.g. toluene, xylene, methyl isobutyl ketone, butyl alcohol, amyl alcohol and isopropyl alcohol.  The compositions may also contain plasticisers, e.g. butyl benzyl phthalate, dibutyl phthalate, triphenyl phosphate, 2-ethylhexyl benzyl phthalate and dicyclohexyl phthalate, pigments, e.g. titanium dioxide, aluminium flake and phthalocyanine blue, modifiers, e.g. dimethyl dioctadecyl ammonium bentonite, other film-formers, e.g. compatible alkyd resins, cellulose acetate butyrate, nitrocelullose, polyethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyvinyl chloride and polyacrylonitrile, and solvents.  The compatibility of the alkyd resin may be improved by modifying with an unsaturated acid, e.g. maleic, itaconic, acrylic or methacrylic acid, and heating with methyl methacrylate, optionally together with the aforementioned copolymerizable monomers, in the presence of a free radical catalyst. The compositions may be coated on to primed steel panels, e.g. for car bodies.  Specification 853,886 is referred to.ALSO:Coated articles comprise a substrate having an adherent multilayer coating comprising a pigmented prime coat in adherent contact with the substrate and one or more superposed topcoats in adherent contact with the prime coat, each topcoat layer having as essential film-forming material at least one polymer of methyl methacrylate, and at least the topcoat adjacent to the prime coat having at least one polymer of methyl methacrylate containing in the polymer chain the radical <FORM:0853885/III/1> wherein one R is a hydroxyl group or a negatively charged oxygen atom and the other R is an amino group bonded through amino nitrogen, said radical constituting 0.2 to 20% of the total weight of methyl methacrylate polymer in said topcoat layer.  The topcoats may be coated from compositions comprising other film-formers, e.g. compatible alkyl resins, cellulose acetate butyrate, nitrocellulose, polyethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyvinyl chloride and polyacrylonitrile; plasticizers, e.g. butyl benzyl phthalate, dibutyl phthalate, triphenyl phosphate, 2-ethylhexyl benzyl phthalate and dicyclohexyl phthalate; pigments, e.g. titanium dioxide, aluminium flake and phthalocyanine blue; modifiers, e.g. dimethyl dioctadecyl ammonium bentonite; and solvents, e.g. toluene, xylene, acetone, methyl isobutyl ketone, glycol monoacetate, butyl alcohol, amyl alcohol and isopropyl alcohol. The primers may comprise oil modified alkyd resins, e.g. soya oil-, linseed oil- or dehydrated castor oil-modified glycerol or pentaerythritol phthalates, alkyd resins modified with urea and melamine formaldehyde resins, poly epoxide resins or oil-modified ester gum varnishes.  Examples describe the coating of steel panels with primers comprising soya oil-modified glycerol phthalate resin, calcium carbonate, carbon black and zinc chromate; or dehydrated castor oil-modified alkyd resin, butylated urea formaldehyde resin, the dehydrated castor oil-modified reaction product of epichlorohydrin and bis-(4-hydroxyphenyl)-2,2-propane, ferric oxide, aluminium silicate, silica, aromatic hydrocarbons and methanol; topcoats comprising (I and II) ammoniated glycidyl methacrylate-methyl methacrylate copolymer, glycidyl methacrylate-methyl methacrylate copolymer aminated with (III) dimethylamine and (IV) N, N-dimethylbenzylamine, these being followed by topcoats comprising methyl methacrylate homopolymer and methyl methacrylate-methacrylic acid; and single topcoats comprising methyl methacrylate homopolymer and ammoniated glycidyl methacrylate-methyl methacrylate copolymer (V) together with nitrocellulose (VI), cellulose acetate butyrate (VIII) and methacrylic modified glycol phthalate-adipate alkyd resin copolymerized with methyl methacrylate; and (VII) methyl methacrylate homopolymer, ammoniated glycidyl methacrylate-lauryl methacrylate-methyl methacrylate terpolymer and coconut oilmodified glycerol phthalate alkyd resin.  Specification 853,886 is referred to.