| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject composition having a high crosslinking rate and productivity, capable of hot-air crosslinking in e.g. a hot-air valcanization tank by specifying the properties of the hot-air crosslinked rubber sheet obtained therefrom. SOLUTION: This composition crosslinkable by hot air or hot press is such that a crosslinked rubber sheet obtained by molding this composition into a sheet-like form followed by hot-air crosslinking of the sheet-like form has the following properties: the surface cannot be scratched at all when subjected to a pencil hardness test using a pencil with a hardness rank of HB, and a hot-press-crosslinked rubber sheet obtained from this composition has the following properties: (1) compression set after heat-treated at 150 deg.C for 22 h is <=70%, (2) the rate of volume change after immersed in an ethylene glycol solution at 120 deg.C for 70 h is -20 to +20%, (3) tensile strength retention, elongation retention and hardness change at 50-150%, >=50% and 0-+50 point after heat- deteriorated at 120 deg.C for 70 h, respectively, (4) tensile strength as a normal-state physical property is 3-20 Mpa, and (5) shot cycles till mold staining is >=30 in a mold stain test.
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