Silicone rubber sponge and rubber-covered roller

摘要

Provided are a silicone rubber sponge that forms an elastic layer of a pressure roller of an image-forming apparatus, and that has a high mechanical strength so as to be used in a high-speed image-forming apparatus or a color image-forming apparatus, and a rubber-covered roller including the silicone rubber sponge. The silicone rubber sponge is produced by mixing expanded resin microballoons with a low-molecular-weight silicone rubber to prepare a compound A, mixing a high-molecular-weight silicone rubber with the compound A to prepare a silicone rubber compound, and heating the silicone rubber compound at a temperature lower than a softening point of the resin microballoons to cure the silicone rubbers.

主权项

1. A silicone rubber sponge produced by mixing expanded resin microballoons with a low-molecular-weight liquid silicone rubber to prepare a compound A, mixing a high-molecular-weight liquid silicone rubber with the compound A to prepare a silicone rubber compound, and
heating the silicone rubber compound at a temperature lower than a softening point of the resin microballoons to cure the silicone rubbers, wherein the relationship M2×0.5<(M1×W1+M2×W2)/(W1+W2) is satisfied, M1 is 8,000 or more and is 15,000 or less, and M2 is 17,000 or more, is 20,000 or less and is equal to or more than 1.2×M1 where M1 represents a mass-average molecular weight of the low-molecular-weight liquid silicone rubber, W1 represents the amount (mass) of the low-molecular-weight liquid silicone rubber in the amount of 60-90 parts by weight, M2 represents a mass-average molecular weight of the high-molecular-weight liquid silicone rubber, and W2 represents the amount (mass) of the high-molecular-weight liquid silicone rubber in the amount of 10-40 parts by weight, so that the sum of W1 and W2 totals 100 parts by weight.