| abstract |
There is disclosed a method for preparing a rubbery cured product of an organopolysiloxane. This product is free from the problems caused by the limited crosslinking velocity or by the necessity of admixing a foreign material such as a crosslinking catalyzing curing agent or a photosensitizer. In this method, a substantially linear diorganopolysiloxane terminated at both chain ends with triorganosilyl groups, each of the triorganosilyl groups having, preferably, 2 or 3 vinyl groups bonded to the silicon atom, is irradiated with ultraviolet light having an energy distribution predominantly rich in the wavelength region from 100 to 300 nm or, preferably, from 180 to 250 nm whereby the energy of the ultraviolet light is most effectively utilized for effecting the crosslinking of the organopolysiloxane. When rapid decrease of the surface tackiness and rapid curing in the depth of a relatively thick layer are desired in the photocuring of the organopolysiloxane by the ultraviolet irradiation, the organopolysiloxane is admixed with small amounts of an organic peroxide. |