| 摘要 |
PCT No. PCT/JP88/00110 Sec. 371 Date Sep. 15, 1988 Sec. 102(e) Date Sep. 15, 1988 PCT Filed Feb. 5, 1988 PCT Pub. No. WO88/05797 PCT Pub. Date Aug. 11, 1988.The polyester film according to the present invention is produced by molding a composition comprising an aromatic polyester, 3 to 40 wt %, based on the amount of said polyester, of a crystalline polypropylene having a melt flow index of 0.2 to 120, and 0.001 to 3 wt %, based of the total amount of said polyester and said polypropylene, of a surface-active agent into a sheet; and stretching the thus obtained sheet at least one direction. The polyester film according to the present invention, which is obtained by the above process is low in the apparent specific gravity because of a large number of minute closed cells contained therein. Further, the polyester film according to the present invention shows a high opacifying power by adding a small amount of titanium oxide or without adding the titanium oxide, which have been added in a large amount. The polyester film can be used as the materials for printing plates and substrates in data devices.
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