| 摘要 |
PURPOSE:To obtain the polyolefin series molded product, improved in a strength against shock in high temperature, having no anisotropism and prominent in molding property, by a comparatively low rolling pressure by a method wherein the temperature of rolling is increased continuously, stepwisely and gradually. CONSTITUTION:In case a crystalline polyolefin series resin is rolled biaxially near the melting point thereof, the temperature of said rolling is increased gradually. The method of increasing the temperature of rolling gradually may be continuously or stepwisely. In case the temperature of rolling is increased stepwisely, the resin is cooled once after effecting first rolling near the melting point of the resin, for example, then, the resin is reheated to a temperature higher than the temperature of first rolling to effect the second rolling. The second rolling may be effected under increasing the temperature immediately after the first rolling without cooling on the half way. In this case, a difference between the temperature of initial rolling and the temperature after the second rolling or a difference between the initial temperature of rolling the the highest temperature of rolling should be 1 deg.K or more and 15 deg.K or less generally. |
