| 摘要 |
PURPOSE: To obtain a good-isotropyβ-crystalline polypropylene synthetic paper for use in high-speed offset printing by crystallizing a film comprising a crystalline propylene polymer and a tetraoxaspiro compd. blended therewith as a nucleating agent at a specific temp. and then stretching it. CONSTITUTION: (A) 100 pts.wt. crystalline propylene polymer is blended with (B) 0.0001 to 5 pts.wt. tetraoxaspiro compd. of the formula I (wherein R<1> and R<2> are each H, 1-20C alkyl, 5-20C cycloalkyl, or the like), and melt-extruded to form a film, which is then crystallized at 10 to 140 deg.C to obtain a raw nonstretched film of aβ-crystalline propylenic polymer, which is then stretched to obtain a synthetic paper. The component (A) may be either a propylene homopolymer or a propylene copolymer, the melt flow rate of which is pref. about 0.1 to 20g/10min. The component (B) is obtd. by amidation of a dicarboxylic acid of the formula II with cyclohexylamine or the like. The raw film pref. contains 40 to 70%βcrystals. The stretching temp. is at least the m.p. ofβcrystals and at most the m.p. ofαcrystals. |
