Process for producing films of low gloss by exposure to ultraviolet light

Claim 1

In the method wherein a coating of an oxygen inhibitable ultraviolet light curable coating composition containing a photoinitiator selected from the group consisting of benzoin, methyl benzoin ether, ethyl benzoin ether, isopropyl benzoin ether, butyl benzoin ether, isobutyl benzoin ether, benzoin acetate, benzoin phenyl carbamate, α,α-diethoxyacetophenone, α,α-diethoxy-α-phenylacetophenone, α,α-dimethoxy-α-phenylacetophenone, 4,4'-dicarboethoxybenzoin ethyl ether, α-chloroacetophenone, α-bromoacetophenone, benzoin phenyl ether, α-methylbenzoin ethyl ether, benzoin acrylate, α-methylolbenzoin methyl ether, α,α,α-trichloroacetophenone, o-bromoacetophenone, 4-(benzoylphenylmethoxycarbonylimino)-2-(acrylyloxyethoxycarbonylimino)-1-methylbenzene, cumene hydroperoxide, benzoyl peroxide, dicumyl peroxide, tert-butyl perbenzoate, α,α'-azobisisibotyronitrile, phenyl disulfide, chloromethylbenzanthrone, chloromethylanthraquinone, chloromethylnaphthalene, bromomethylbenzanthrone, bromomethylanthraquinone and bromomethylnaphthalene, an oxygen inhibitable resin having acrylic unsaturation and a flatting pigment which is generally transparent to ultraviolet light is exposed to ultraviolet light in an atmosphere containing a low gloss imparting amount of oxygen to gel the surface of said coating and to cure the interior of said coating to a greater degree of cure than said surface and thereafter said exposed coating is exposed to ultraviolet light in an atmosphere wherein any oxygen present is insufficient to significantly inhibit free radical curing of said gelled surface, whereby said coating is cured into a hard, mar and abrasion resistant film having a surface of low gloss, the improvement wherein said coating composition contains an air cure promoter selected from the group consisting of anthraquinone, thioxanthone, 4-chlorobenzophenone, 4-methoxybenzophenone, benzophenone, 2-chloroanthraquinone, dibenzosuberone, o-benzoylbenzophenone, chlorinated terphenyls, mercaptoacetic acid and mercaptoethanol in an amount which will impart to said cured film a lower gloss than if said air cure promoter were absent.