Patent ID: 8721948

Claim:
A method for producing a crosslinked fluororubber product, comprising: pressurizing, heating, and vulcanizing a fluororubber composition to mold a vulcanized product; the fluororubber composition comprising a polyol-crosslinkable fluororubber, a crosslinking accelerator including a quarternary phosphonium salt, and a polyol crosslinking agent, the weight ratio X of the crosslinking accelerator to the polyol crosslinking agent (crosslinking accelerator/polyol crosslinking agent) being from 0.90 to 3.00; applying a treatment solution containing the polyol crosslinking agent and the crosslinking accelerator dissolved in a solvent to a surface of the vulcanized product; and heat-treating the resulting vulcanized product at a temperature ranging from 200 to 300° C. until a magnet tackiness increase rate according to an evaluation method II is 10% or lower, wherein in the evaluation method II, a sample rubber sheet with a thickness of 0.4 mm, a length of 3 mm, and a width of 3 mm is placed on a permanent magnet shaped as a square column with a thickness of 3.6 mm, a length of 3 mm, and a width of 3 mm, whose bottom is fixed; a metal rod, made of SPCC, a cold rolled steel plate, with a weight of 30 g, where the shape of the portion contacting the rubber is a 3 mm times 1 mm square rod, is placed on the sample rubber sheet, and an initial tackiness F between the rubber and the metal rod is measured at 23° C. and a humidity of 50%; the metal rod is then placed on the sample rubber again, and a test unit including the magnet, the sample rubber, and metal rod is allowed to stand at 80° C. for 2 hours, and subsequently at 0° C. for 2 hours; the test unit is repeatedly subjected to 20 cycles of being allowed to stand under such a temperature change, and removed from the atmosphere at 0° C. after the final cycle; the tackiness F″ is then measured, and using the measured values F, F″, the tackiness increase rate (%) is determined in accordance with the following equation: (Tackiness Increase Rate) =100 times (F″−F)/F.