Pasty heat-expandable filler composition and method of sound insulation by filling closed section of car body member

Abstract

An automatic injecting type paste form heat-blowing injection composition comprising a partially crosslinked rubber, an unvulcanized rubber, a crosslinking agent, a plasticizer, a thermoplastic resin, an epoxy resin and a latent curing agent thereof, and a blowing agent. This composition can be used in a injecting and soundproofing method comprising forming an insulation wall by heating and foaming of a injection composition in a closed section of an automobile body part having a closed section frame which is produced by press molding in a body welding step of an automobile manufacturing line, and it has a good anti-stringy property and suffers form less sagging during heating and foaming.

1 . An automatic injecting type paste form heat-blowing injection composition comprising a partially crosslinked rubber, an unvulcanized rubber, a crosslinking agent, a plasticizer, a thermoplastic resin, an epoxy resin and a latent curing agent thereof, and a blowing agent.  
     
     
         2 . The paste form heat-blowing injection composition according to  claim 1 , which comprises, based on the whole weight of the composition, 1 to 10% by weight of the partially crosslinked rubber, 1 to 10% by weight of the unvulcanized rubber, 0.01 to 5% by weight of the crosslinking agent, 30 to 50% by weight of the plasticizer, 1 to 15% by weight of the thermoplastic resin, 0.5 to 10% by weight of the epoxy resin, 0.05 to 5% by weight of the latent curing agent, and 1 to 10% by weight of the blowing agent, and which has a viscosity of 30 to 500 Pa·s (at 20° C.) and a blowing start temperature of at least 100° C.  
     
     
         3 . A method for injecting and soundproofing a closed section of an automobile body part comprising the steps of: 
 applying an automatic injecting type paste form heat-blowing injection composition to a closed section of an automobile body part having a closed section frame, which is press molded in a body welding step of an automobile manufacturing line, prior to the assembling of the body part,    carrying the automobile body part applied with the heat-blowing injection composition to a pretreatment and electrodeposition coating step, and    heating and blowing the injection composition under baking conditions in an electrodeposition oven in an electrodeposition coating step to fill the closed section with an insulation wall made of the foamed material of the injection composition, wherein an automatic injecting type paste form heat-curable damming injection composition is applied in adjacent to the paste form heat-blowing injection composition or at a distance from the injection composition, thereby the sagging of the injection composition is prevented by the gelled damming injection composition when the insulation wall formed from the injection composition insufficiently fill the closed section because of the sagging of the heat-blowing injection composition during heating and blowing.    
     
     
         4 . The method according to  claim 3 , wherein said automatic injecting type paste form heat-curable damming injection composition comprises a partially crosslinked rubber, a plasticizer, a thermoplastic resin, and optionally an epoxy resin and a latent curing agent thereof.  
     
     
         5 . The method according to  claim 3 , wherein said automobile body part having a closed section frame is an A pillar, an B pillar, a C pillar, a wheel arch (tire housing) or a side sill.  
     
     
         6 . The method according to  claim 3 , wherein said automatic injecting type paste form heat-blowing injection composition comprises a partially crosslinked rubber, an unvulcanized rubber, a crosslinking agent, a plasticizer, a thermoplastic resin, an epoxy resin and a latent curing agent thereof, and a blowing agent.  
     
     
         7 . The method according to  claim 4 , wherein said paste form heat-curable damming injection composition comprises, based on the whole weight of the composition, 1 to 15% by weight of the partially crosslinked rubber, 20 to 40% by weight of the plasticizer, 5 to 20% by weight of the thermoplastic resin, 10% by weight or less of the epoxy resin and 5% by weight or less of the latent curing agent thereof, and which has a viscosity of 30 to 500 Pa·s (at 20° C.)  
     
     
         8 . An automatic injecting type paste form heat-curable damming injection composition comprising a partially crosslinked rubber, a plasticizer, a thermoplastic resin, and optionally an epoxy resin and a latent curing agent thereof.  
     
     
         9 . The paste form heat-curable damming injection composition according to  claim 8 , which comprises, based on the whole weight of the composition, 1 to 15% by weight of the partially crosslinked rubber, 20 to 40% by weight of the plasticizer, 5 to 20% by weight of the thermoplastic resin, 10% by weight or less of the epoxy resin and 5% by weight or less of the latent curing agent thereof, and which has a viscosity of 30 to 500 Pa·s (at 20° C.), a gelation start temperature of 90° C. or less and a viscosity after gelation of at least 100,000 Pa·s.  
     
     
         10 . A filled and soundproofed structure comprising an automobile body part having a closed section frame, which is filled and soundproofed by the method according to  claim 3.