Patent ID: 6765046
Filing Date: 2004-07-20
Classification: C08F,C08K

Abstract:
A method for producing a molding composition consisting of a polymer comprised of 80-100 weight-percent of methyl methacrylate monomer units and 0-20 weight-percent of C1-to C4-alkyl ester of acrylic acid monomer units and a reducing inorganic phosphorus compound, wherein the method comprises:adding to said polymer 0.0005 to 0.005 weight-percent, based on the weight of said polymer, of one or more reducing inorganic phosphorus compounds selected from the group consisting of phosphinic acid, phosphonic acid, alkali metal salts of phosphinic acid, alkali metal salts of phosphonic acid, alkaline earth salts of phosphinic acid, alkaline earth salts of phosphonic acid, aluminum salts of phosphinic acid, aluminum salts of phosphonic acid, ammonium salts of phosphinic acid, and ammonium salts of phosphonic acid, wherein the ammonium salts may be substituted with up to four C1-to C4-alkyl and/or C5-to C8-cycloalkyl groups, and wherein a molding of 100 mm thickness prepared from said molding composition has a transmission of 89-92%, and wherein the yellow index according to DIN 6167 (D65/10E) or according to ASTM D 1925 of a molding of 100 mm thickness prepared from said molding composition is at least 40% lower than a molding of 100 mm thickness prepared from said molding composition without said one or more reducing inorganic phosphorus compounds. 2.The method of claim 1, wherein said reducing inorganic phosphorus compounds are added in an amount of 0.001 to 0.003 wt. %, based on the weight of said molding composition.