Curable organosiloxane compositions

• US 4,677,161 A
• Filed: 05/12/1986
• Issued: 06/30/1987
• Est. Priority Date: 05/16/1985
• Status: Expired due to Term

• Current Assignee: Ltd. Toray Silicone Company
• Original Assignee: Ltd. Toray Silicone Company
• Inventors: Suzuki, Toshio, Muramoto, Naohiro, Shirahata, Akihiko
• Primary Examiner(s): Marquis, Melvyn I.
• Application Number:
  US06/861,881
• Time in Patent Office: 414 Days
• Field of Search: 528/15, 528/31, 528/32, 524/861, 524/862, 524/731, 525/478
• US Class Current: 524/862
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 83/04 Polysiloxanes

Abstract

This invention provides self-adhering polyorganosiloxane compositions that cure by a platinum-catalyzed hydrosilation reaction. The compositions include as the adhesion promoter a polysiloxane comprising diorganohydrogensiloxy, alkoxy and SiO_4/2 units.

Claims

1. A curable organosiloxane composition comprising

(a) a polyorganosiloxane having an average unit formula R_a SiO.sub.(4-a)/2, where R represents a monovalent hydrocarbon radical, with the proviso that at least two of the R radicals in each molecule are lower alkenyl, and the value of a is from 0.8 to 2.2, inclusive;

(b) a polyorganohydrogensiloxane containing at least 2 silicon-bonded hydrogen atoms per molecule and which is substantially free of silicon-bonded alkoxy groups and alkenyl radicals, the quantity of polyorganohydrogensiloxane being sufficient to provide a molar ratio of silicon-bonded hydrogen atoms in ingredients (b) and (d) to the moles of alkenyl radicals in ingredient (a) of from 0.5;

1 to 3.0;

1, respectively;

(c) a platinum-containing hydrosilation catalyst in an amount equivalent to from 0.1 to 100 ppm by weight of platinum, based on the combined weight of ingredients (a), (b) and (c);

(d) from about 1 to 20%, based on the weight of ingredient (a), of a polysiloxane represented by the general formula (HR'"'"'₂ SiO_1/2)_b (R"O_1/2)_c (SiO_4/2)_d where R'"'"' and R" represent monovalent hydrocarbon radicals containing from 1 to 3 carbon atoms, the value of b/c in said general formula is from 0.2 to 2, inclusive, the value of b+c)d in said general formula is from 0.4 to 4, inclusive, and d represents a number greater than 0 and less than 30.

2. A composition according to claim 1 where the alkenyl radical present in ingredient (a) is a vinyl radical, at least 75 percent of the R radicals are methyl and the value of a is from 1.95 to 2.05.

3. A composition according to claim 2 where ingredient (a) is a vinyl terminated polydimethylsiloxane exhibiting a viscosity of from 0.05 to 100 Pa.s at 25°

C. and the viscosity of ingredient (b) is from 0.001 to 50 Pa.s at 25°

C.

4. A composition according to claim 3 where ingredient (b) is a dimethylsiloxane/methylhydrogensiloxane copolymer or a copolymer corresponding to the formula [H(CH₃)₂ SiO_1/2 ]₁₄ (SiO_4/2)₉.

5. A composition according to claim 3 where ingredient (c) is present in an amount equivalent to a platinum content of from 1 to 20 parts per million, based on the combined weight of ingredients (a), (b), and (c).

6. A composition according to claim 3 where R'"'"' is methyl, R" is methyl or ethyl, the value of d is from 3 to 20 and the concentration of ingredient (d) is from 1 to 8 parts by weight per 100 parts of ingredient (a).

7. A composition according to claim 6 where ingredient (d) is selected from the group consisting of [H(CH₃)₂ SiO_1/2 ]₉ (CH₃ O_1/2)₉ (SiO_4/2)₁₂, and [H(CH₃)₂ SiO_1/2 ]₈ (CH₃ O_1/2)₁₄ (SiO_4/2)₁₄.

8. A composition according to claim 7 where said composition contains an inhibitor for the curing reaction selected from the group consisting of acetylene compounds, alkenyl group-containing compounds, hydrazines, triazoles, phosphines and mercaptans.

9. A composition according to claim 8 where said inhibitor is 3-methyl-1-butyn-3-ol.

10. A composition according to claim 3 where ingredient (a) includes a polysiloxane corresponding to the formula [CH₂ ═

CH(CH₃)₂ SiO_1/2 ]₈ (SiO_4/2)₄.

11. A composition according to claim 3 containing finely divided silica as a filler.