| 摘要 |
PURPOSE:To form a beautiful skin on the sponge seal part of a sulfur- vulcanizable rubber extrudate stably, by previously applying a specified amount of a heated softener or plasticizer to the sponge seal part in vulcanizing the sulfur-vulcanizable rubber extrudate. CONSTITUTION:In vulcanizing a sulfur-vulcanizable rubber extrudate W fitted with a sponge seal part 1, a softener (e.g., aromatic process oil) or a plasticizer (e.g., dibutyl phthalate, heated to 80-300 deg.C) is previously applied to the surface of the sponge seal part 1 of the unvulcanized rubber extrudate W. The amount of the softener or the plasticizer applied should be such that it is diffused into the rubber and does not remain on the surface when the vulcanization is completed. The vulcanization is completed by heating at normal pressure for a definite time. In this way, it is possible to obtain the sponge seal part 1 of a fine skin because the heated softener or plasticizer is applied to the surface and the vulcanization of the surface occurs earlier by this heat to form a skin layer not affected by foaming.
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