| 摘要 |
PROBLEM TO BE SOLVED: To provide a rubber compound composed mainly of a styrenebutadiene rubber (SBR) continuously vulcanizable in molding, an ethylene-propylene-diene rubber (EPDM) and carbon black, provide a specific molded rubber article having high strength and provide a ring-shaped water-stopping material for the sealing of a joint of especially a large-sized plastic pipe for waterworks and drainage system. SOLUTION: This rubber compound is produced by compounding an SBR having a Mooney viscosity (ML1+4 , 100 deg.C) of 123-133 with a prescribed amount of MAF carbon black having an average particle diameter of 38.6μm and a nitrogen-adsorption specific surface area of 54.4m<2> /g together with a processing assistant, separately compounding an EPDM mixture having an iodine value of 28 and a weight-average molecular weight of 664,500 with prescribed amounts of a vulcanizing agent, a vulcanization accelerator, a defoaming agent, etc., and mixing both mixtures obtained by the above procedures. A ring-shaped water-stopping material can be produced by forming a continuous water- stopping material from the rubber compound with an extruder, continuously introducing the extrudate into a hot tunnel to effect the vulcanization of the rubber compound, cutting to a prescribed length and bonding both ends of the cut extrudate. |
