Method of making a molded article of methacrylic resin

Claim 1

A method for the production of a molded article of methacrylic resin formed of a cross-linked polymer having at least part of the surface thereof coated with an abrasion resistant layer, which method comprises placing (A) an abrasion resistant layer-forming material selected from the group consisting of (a) cross-linked polymerizing compounds having a molecular weight of not less than 150 and containing at least two (meth)acryloyloxy groups per molecule, (b) mixtures of at least 30% by weight of said cross-linked polymerizing compounds with other copolymerizable monomers, and (c) partial polymerization products thereof, and possessed of a composition such that the number, x, of said (meth)acryloyloxy groups of said cross-linked polymerizing compound and the ratio of polymerization, y (%), of said scratch proofing layer-forming material satisfy the following formula I or II: y≦70 (2≦x≦3.5) (I) y≦-7.5x.sup.2 +52x-18 (3.5<x≦6) (II) in contact with (B) a basic molding material made of an acrylic partially cross-linked gelled polymer obtained by partially polymerizing a mixture of (i) a resin material selected from the group consisting of alkyl methacrylate monomers, mixtures of alkyl methacrylates as main components with α, β-ethylenically unsaturated monomers, and syrups weight, based on 100 parts by weight of said resin material, of a cross-linking agent and stopping said partial polymerization when the gel content of the basic molding material reaches a level in the range of 15 to 95% thereby allowing said material consequently produced to possess the property of retaining the polymerization in a stopped state, and simultaneously polymerizing said two materials held in mutual contact under a condition capable of imparting a desired shape to the combined materials.

Claim 2

A method for the production of a molded article of methacrylic resin formed of a cross-linked polymer having at least part of the surface thereof coated with an abrasion resistant layer, which method comprises placing (A) an abrasion resistant layer-forming material selected from the group consisting of (a) cross-linked polymerizing compounds having a molecular weight of not less than 150 and containing at least two (meth)acryloyloxy groups per molecule, (b) mixtures of at least 30% by weight of said cross-linked polymerizing compounds with other copolymerizable monomers, and (c) partial polymerization products thereof, and possessed of a composition such that the number, x, of said (meth)acryloyloxy groups of said cross-linked polymerizing compound and the ratio of polymerization, y (%), of said scratch proofing layer-forming material satisfy the following formula I or II: y≦70 (2≦x≦3.5) (I) y≦-7.5x.sup.2 +52x-18 (3.5<x≦6) (II) in contact with (B) a basic molding material made of an acrylic partially cross-linked gelled polymer obtained by partially polymerizing a mixture of (i) a resin material selected from the group consisting of alkyl methacrylate monomers, mixtures of alkyl methacrylates as main components with α, β-ethylenically unsaturated monomers, and syrups weight, based on 100 parts by weight of said resin material, of a cross-linking agent and stopping said partial polymerization when the gel content of the basic molding material reaches a level in the range of 15 to 95% thereby allowing said material consequently produced to possess the property of retaining the polymerization in a stopped state, and simultaneously polymerizing said two materials held in mutual contact under a condition capable of imparting a desired shape to the combined materials.