| 摘要 |
PROBLEM TO BE SOLVED: To obtain a composition which suffers little thermal coloration even molded at a high temperature and exhibits excellent balanced properties by admixing a phenolic compound and a phosphor-containing compound each in a specific amount with a copolymer comprising methyl methacrylate units, cyclohexyl methacrylate units and benzyl methacrylate units each in a specific ratio. SOLUTION: To 100 pts.wt. of a copolymer comprising 50-75 wt.% of methyl methacrylate units, 20-45 wt.%, of cyclohexyl methacrylate units, 5-20 wt.% of benzyl methacrylate units, and optionally not more than 10 wt.% of units of other copolymerizable monomers (e.g. methyl acrylate) are added 0.01-0.15 pt.wt. of a phenolic antioxidant represented by formula I and 0.01-0.15 pt.wt. of a phosphor-containing antioxidant represented by formula II. The composition suffers little thermal coloration at a temperature of 200 deg.C or higher when molded and is excellent in balance among low hygroscopicity, low birefringence and heat resistance. In the formula X is t-butyl; and R is a 12-15C alkyl. |
