Abstract: An improved steel cord for reinforcing rubber is formed of three steel filaments, one having a smaller diameter than the other two, twisted together. The thinner filament is twisted with the two filaments at least partially in contact with them and with the same pitch. When the steel cord is cut at both ends, the thinner filament is retracted inwardly from the ends of the two filaments. This improves the penetration of rubber into the cord and prevents edge separation.

Abstract: A method for preparing 2,2-bis(4-hydroxyphenyl)propane comprises reacting acetone and phenol in the presence of an acidic ion-exchange resin as a catalyst wherein the reaction of acetone and phenol is performed while removing a part of the water generated during the reaction from a mixed solution containing acetone and phenol by a pervaporation method. According to the method, the water generated through the reaction can rapidly be removed simultaneously with or alternatively to the reaction by a pervaporation operation and, therefore, the catalytic activity of the ion-exchange resin is not impaired at all. Moreover, any complicated operations associated with the dehydration are not required. Thus, the acidic ion-exchange resin catalyst can continuously be used over a long time period without any treatment for the regeneration thereof. Further, according to the method, bisphenol A can be economically prepared from acetone and phenol in a high conversion rate and high yield.

Abstract: A high-elongation composite cord used for reinforcing a rubber composite such as a wheel tire and a conveyor belt. It is made by twisting a plurality of strands each made by twisting a plurality of brass-plated steel filaments and monofilaments of organic fiber. Before twisting the cord, monofilaments of organic fiber are put in the gaps formed between the adjacent strands so as to prevent fluidized rubber from penetrating into a center core formed in the cord after the cord has been covered with rubber. The monofilaments should have a diameter small enough not to protrude from a circle circumscribing the cord and large enough to close the gaps between the adjacent strands.

Abstract: A steel cord for reinforcing rubber is made by twisting a plurality of strands each made by twisting a plurality of element wires. The cord and the strands are twisted in the same direction. The product of the twisting ratio of the cord and that of the strands, the elongation coefficient of the cord and other factors are determined so that the rubber penetration and the rigidity and tenacity of the cord will be suitable for the carcass cord of steel radial tire.