| 摘要 |
PURPOSE:To obtain a magnetic disk cartridge which excels in thermal stability, shock resistance, etc. by using a hard polyvinyl chloride sheet having low temperature side peak higher than a high temperature side peak in case two heat absorption peaks of a differential thermal analysis exist in a specific temperature range where one or two said peaks exist normally. CONSTITUTION:An oblong material 4 of a heat resistant hard polyvinyl chloride sheet having a low temperature side peak higher than a high temperature side peak is used in case two heat absorption peaks of a differential thermal analysis exist within a 60- 105 deg.C range. The said hard polyvinyl chloride is obtained by processing a copolymer of No.405 post-chlorinated polyvinyl [made of SUMITOMO Bakelite Company, polyvinyle chloride, (metha)acrylic acid ester, etc. for a prescribed period of time in a range of (Tg-40) deg.C-Tg with the glass transition temperature set at Tg( deg.C)]. A cleaning sheet 3 of unwoven fabric of polypropylene, etc. is put on said polyvinyl sheet and partially unified with thermal fusing. Then this laminated sheet is folded at a point near a folding line 6 with heating, and edge parts 5 and 5'' are folded with heat fusing. A magnetic disk 2 is put into a hollow part, and an edge part 5' is folded and fixed with a paste agent. Thus it is possible to obtain a cartridge which excels in the size stability at a high temperature, the impact resistance at a low temperature, etc.
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