Response of Elastomers to High Temperature Cure

Abstract It is well known to production people and to process engineers engaged in manufacturing rubber products that the output of curing operations can be greatly increased by elevating the temperature of vulcanization. For example, work done in the 1920's led to the curing of rubber-covered wire at 400° F using a continuous vulcanization (CV) process. Highly accelerated compounds capable of complete vulcanization in 15 seconds at 400° F are used in the wire industry. More recently the application of high temperature vulcanization methods has been vigorously pressed in the tire industry. While exact curing cycles are closely guarded secrets, it can be stated that passenger tires are vulcanized at temperatures up to 388° F (200 psi steam pressure) using press cycles of the order of 15 to 25 minutes' duration. New automatic presses which shape and then cure the tires at high temperatures—for example, Bagomatic tire curing press, McNeil Machinery & Engineering Co., Akron, Ohio—permit large economies in labor and productivity. Further reductions in curing cycles are anticipated, since the process engineers and rubber technologists continue to develop improved methods of high temperature curing. At this time it appears that the trend to higher temperature vulcanization will not only continue but tend to expand into other lines of rubber products. Considering the economic advantages which a given company may gain by a major advance in high temperature curing of tires or other rubber goods, it is not surprising that there have been only a few disclosures on high temperature curing technology.