| abstract |
(57) [Summary] [Purpose] A reinforcing agent is added to a raw material rubber in which ethylidene norbornene as a third component is selected for a copolymer of ethylene as a first component and propylene as a second component. A rubber sheet for a butterfly valve that is vulcanized and formed.For example, even when this butterfly valve is used in a pipe line that passes hot water into the pipe, the rubber in the rubber sheet of this valve deteriorates or elutes from the rubber. A rubber sheet for a butterfly valve, which does not pollute water with the above components, has a small compression set, and is excellent in wear resistance. [Structure] The weight percentage of propylene as the second component is 3 The iodine value of the raw rubber is 18, and the Mooney viscosity ML is 1%. 1 + 4 (100 ° C.) is set to 34, the reinforcing agent is an inorganic reinforcing agent, and the raw rubber is vulcanized by adding an organic peroxide and a silane coupling agent as a vulcanizing system. |