| 摘要 |
PURPOSE:To make a copolymer colorless and transparent, to lower the birefringence and to improve the heat resistance, moldability and low moisture absorbency by incorporating methyl methacrylate units, specific methacrylate units, aromatic vinyl units, methacrylic acid units and 6-membered ring acid anhydride units. CONSTITUTION:Methyl methacrylate (A) is copolymerized with a methacrylate (B) of formula I (wherein R is a 6-20C alicyclic hydrocarbon group), an aromatic vinyl (C) and methacrylic acid (D) in the presence of a radical polymerization initiator and a chain transfer agent to produce a lowly moisture-absorptive copolymer which comprises the constituent units (A), (B), (C), (D), and 6-membered ring acid anhydride units (E) of formula II, and wherein when the contents of the constituent units are assumed to be a, b, c, d and e wt.%, respectively, 93.9>=a>=25, 49>=b>=5, 30>=c>=0, 20>=d>=0.1, 40>=e>=1, 98.9>=a+b>=50, 98.9>=a+b+c>=60, and a+b+c+d+e=100, and the volatiles content is 1.5 or below, the reduced viscosity (measured at 25 deg.C as a solution of 0.15g of the copolymer in 0.5dl of chloroform) is 0.2-1.0dl/g.
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