| 摘要 |
PURPOSE:To obtain an oriented film or sheet of improved impact strength by specifying the sum of the absolute value of the birefringence index involving the direction of molecular chains of a film or sheet made of a specified polyglutarimide resin and the direction rectangular thereto and the absolute value of the birefringence index involving the direction of thickness of the film or sheet. CONSTITUTION:A polyglutarimide resin comprising at least 20wt.% repeating units of the formula (wherein R1 nd R2 are each H or a 1-4C hydrocarbon group; and R3 is H, a 1-12C hydrocarbon group, a cycloalkyl, benzyl, phenyl, naphthyl or the like) and having a number-average molecular weight of about 10000 or above is extruded to form an unoriented film or sheet of a thickness of about 1mum-10mm. This film or sheet is biaxially oriented at a draw ratio of about 1.3-4.0 in a temperature range higher than the glass transition temperature of the resin by about 5-40 deg.C with a biaxial orienting machine to obtain a biaxially oriented film or sheet having markedly improved impact strength and satisfying the conditions that the sum of the absolute value of the birefringence index involving the direction of molecular chains of the film or sheet and the direction of thickness of the film or sheet and the absolute value of the birefringence index involving the direction of thickness of the film or sheet is 2X10<-3> or above. |
