Method for preparing cured rubbery products of organopoly-siloxanes

• US 4,364,809 A
• Filed: 03/05/1980
• Issued: 12/21/1982
• Est. Priority Date: 03/19/1979
• Status: Expired due to Term

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Inomata, Hiroshi, Sato, Yasuhiko, Okinoshima, Hiroshige
• Primary Examiner(s): Bleutge, John C.
• Assistant Examiner(s): KOECKERT JR, ARTHUR
• Application Number:
  US06/127,523
• Time in Patent Office: 1,021 Days
• Field of Search: 204/159.13
• US Class Current: 522/60
• CPC Class Codes: C08F 292/00 Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• CPC Class Codes: C08F 299/08 from polysiloxanes
• CPC Class Codes: C08F 30/08 containing silicon
• CPC Class Codes: C08G 77/06 Preparatory processes C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/70 Siloxanes defined by use of the MDTQ nomenclature
• CPC Class Codes: C08K 5/14 Peroxides
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: G03F 7/0757 Macromolecular compounds containing Si-O, Si-C or Si-N bonds G03F7/0752 takes precedence
• CPC Class Codes: Y10S 525/925 Polymer from at least one nonethylenic monomer having terminal ethylenic unsaturation other than polyurethanes, polyesters, polyepoxides, aminoplasts, and phenoplasts

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.

Claims

1. A method for the preparation of a rubbery cured product of an organopolysiloxane which comprises irradiating an organopolysiloxane containing aliphatically unsaturated groups and having a substantially linear molecular structure as represented by the general formula ##STR3## wherein R¹ is a methyl or a phenyl group

R² is a substituted or unsubstituted monovalent hydrocarbon group, m is zero, a is 2 or 3, and n is zero or a positive integer, with ultraviolet light in the wavelength region from 100 to 300 nm in the absence of a photosensitizer and the molar ratio of the aliphatically unsaturated groups to all of the hydrocarbon groups represented by the symbol R² in a molecule of the organopolysiloxane is 10% or less.

2. The method of claim 1 wherein the molar ratio of aromatic hydrocarbon groups represented by the symbols R¹ and R² to the silicon atoms in a molecule is up to 0.03.

3. The method of claim 1 wherein the number n is at least 10.

4. The method of claim 1 wherein the organopolysiloxane is admixed with an organic peroxide.

5. The method of claim 4 wherein the amount of the organic peroxide is from 0.1 to 10% by weight based on the organopolysiloxane.