Patent ID: 6588471
Filing Date: 2003-07-08
Classification: B29D,B29K,B29L

Abstract:
A method of preparing an assembly of a partially cured rubber composition and an uncured rubber composition followed by sulfur curing said assembly which comprises:(A) partially sulfur curing a sulfur curable rubber composition to from about 10 to about 80 percent of its sulfur cured condition within a rigid mold for the partially curing thereof at a temperature in a range of about 120Â° C. to about 200Â° C.; (B) removing said partially cured rubber composition from said rigid mold for the partially curing thereof and allowing said partially cured rubber composition to cool to a temperature of less than 40Â° C.; (C) applying said partially pre-cured rubber composition to an uncured, sulfur curable, rubber composition to form an assembly thereof; (D) sulfur curing said assembly in a suitable mold for the sulfur curing thereof at a temperature in a range of about 120Â° C. to about 200Â° C., and (E) removing said sulfur cured assembly from said mold for the sulfur curing thereof in a subsequent cooling step and allowing said cured assembly to cool to a temperature of less than 40Â° C.; wherein for said partially cured rubber composition: (1) said partially curing and cooling steps for said partially cured rubber composition are conducted in a nitrogen atmosphere to the exclusion of oxygen, (2) said partially cured rubber composition contains from about 0.1 to about 3 phr of a bis-imide selected from N,Nâ€²-m-xylylene-bis-citraconimide and N,Nâ€²-m-phenylene bismaleimide blended therewith, and (3) said partially cured rubber composition is immediately, following its removal from said rigid mold for the partial curing thereof, immersed in water, said water having a temperature within about 0Â° C. to about 20Â° C. to rapidly cool the partially cured rubber composition to a temperature of less than 100Â° C.