Patent GB-1450244-A (GB)
Title: Photo-curable composition for coating
IPC: C08F299/06
Filed: 1974-01-31
Abstract: 1450244 Photo-curable polymer compositions NIPPON PAINT CO Ltd 31 Jan 1974 [1 Feb 1973] 04532/74 Headings C3G and C3P A photo-curable coating composition comprises (A) a polymer having a ratio of the molecular weight to the number of polymerizable double bonds of 200-10,000, said polymer being the product of a reaction between an isocyanate compound containing a polymerizable double bond and a polymer or prepolymer containing an active hydrogen atom; (B) a monomer or oligomer polymerizable therewith; (C) a photo-sensitizer wherein the weight ratio of (A) : (B) : (C) is 20-99 : 80-1 : 0À01-20 and (D) a colouring agent in an amount of 3-50 parts by weight per 100 parts of (A) + (B) + (C). An organic solvent diluent may be present. Polymer (A), is prepared by reacting a monomer containing a polymerizable double bond and an active hydrogen atom with a polyfunctional isocyanate, and reacting the product with a polymer containing at least one active hydrogen atom. Di- and triisocyanates are preferred, the polymers containing the active hydrogen atom being preferably polyester polyols or acrylic polyols. Monomer (B), which includes oligomers, is selected from one or more of styrene compounds (styrene, vinyltoluene, t-butylstryene, monochlorostyrene, α-methylstyrene, divinylbenzene); vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate); (meth)acrylate compounds (methyl(meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, methoxybutyl (meth) acrylate, 1,6 - hexanediol di-(meth)acrylate, trimethylolpropane tri - (meth)acrylate); allyl compounds (allylmethacrylate, triallyl isocyanate); unsaturated nitriles (acrylonitrile); α,# - unsaturated amides (acrylamide, N- butoxymethylacrylamide); and diesters of unsaturated polycarboxylic acids (diethyl itaconate, dibutyl itaconate, diethyl fumarate, dibutyl fumarate, dimethyl maleate, dibutyl maleate). The preferred photo-sensitizers (C) are benzoin, benzoin ethers, benzophenone, benzil, 2,4 - dichlorobenzaldehyde and disulphides. The compositions may be coated on to substrates and cured with ultraviolet light. In the reference examples urethane-modified polymer compositions (Z) are prepared by reaction of a polyester prepolymer derived from glycidyl methacrylate and a polyester polyol of phthalic anhydride, tetrahydrophthalic anhydride, adipic acid, ethylene glycol, "Cardura E" and "Epiclon" with an isocyanate compound derived from either (i) xylylene diisocyanate (a mixture of #,#<SP>1</SP>-diisocyanato-1,3-dimethylbenzene and #,#<SP>1</SP>-diisocyanato-1,4-dimethylbenzene) and 2-hydroxyethyl methacrylate or (ii) isophorone diisocyanate and glycidyl methacrylate, followed by the addition of methylmethacrylate; reaction of an acrylic polyol derived from styrene, methyl methacrylate, n-butyl acrylate, and 2-hydroxyethylmethacrylate with methyl methacrylate, followed by an isocyanate compound derived from xylylene diisocyanate, tetrahydrophthalic anhydride, 2- hydroxyethyl methacrylate and glycidyl methacrylate. The reactions are carried out in the presence of a conventional urethanation catalyst and, optionally, polymerization inhibitor. Examples 1-12 describe compositions of the urethane-modified polymers as (A); triallyl isocyanurate, trimethylolpropane trimethacrylate, N-butoxymethylacrylamide or tetrahydrofurfuryl methacrylate as (B); benzoin methyl ether or benzoin isopropyl ether as (C); and various pigments, which are cured with ultraviolet light to yield coatings of specified hardness and thickness. ("Cardura" and "Epiclon" are Registered Trade Marks).