| 摘要 |
The present invention relates to a process for producing a polypropylene sheet or film which comprises passing a molten sheet or film of a polypropylene composition, the composition comprising polypropylene and at least one additive selected from the group consisting of a nucleating agent, a finely powdered high melting point polymer, a petroleum resin, a terpene resin, an organic peroxide and a crystalline propylene-based copolymer, between two cooling rolls opposite to each other, the rolls being maintained at a temperature of 10 to 50 DEG C , and being subjected to specular finishing treatment , and adapted so as to convey therebetween a metallic endless belt having a surface roughness of not more than 1.5 mu m under tension , while carrying the sheet or film on the endless belt . In accordance with the present invention, there can be obtained a polypropylene sheet or film excellent in transparency and surface gloss although not stretched. The sheet or film obtained is good in transparency and surface gloss even though it is thick-walled. Moreover the present invention permits to produce the sheet or film as described above at a high speed, and it has an advantage of being excellent in productivity because the process can be carried out at relatively high temperatures compared with water cooling, for example. <IMAGE> |
