Silicone rubber compositions

• US 5,548,006 A
• Filed: 11/17/1994
• Issued: 08/20/1996
• Est. Priority Date: 11/18/1993
• Status: Expired due to Fees

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Nakamura, Tsutomu, Hirabayashi, Satao
• Primary Examiner(s): Sweet, Mark D.
• Application Number:
  US08/341,085
• Time in Patent Office: 642 Days
• Field of Search: 524/82, 524/100, 524/101, 524/392, 524/588, 525/478, 528/15, 528/21, 528/23, 528/31
• US Class Current: 524/82
• CPC Class Codes: C08K 5/0025 Crosslinking or vulcanising agents; including accelerators
• CPC Class Codes: C08K 5/3492 Triazines
• CPC Class Codes: C08K 5/37 Thiols
• CPC Class Codes: C08L 83/04 Polysiloxanes

Abstract

An addition curing type silicone rubber composition comprising an aliphatic unsaturated group-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum series catalyst is further blended with a triazine or sulfide control agent to provide a composition which is stable and resistant against premature gelation at room temperature and thus has long-term storage stability. Heating causes the composition to be quickly vulcanized at an acceptable rate into a silicone rubber having satisfactory physical properties.

Claims

1. A silicone rubber composition comprising

(A) an organopolysiloxane of the following avenge compositional formula (1):

space="preserve" listing-type="equation">R.sup.1.sub.a SiO.sub.(4-n)/2 (

     1)

wherein R¹ is a substituted or unsubstituted monovalent hydrocarbon group, the R¹ groups may be identical or different, and letter n is a positive number of 1.98 to 2.02, containing at least two aliphatic unsaturated groups in a molecule,

(B) an organohydrogenpolysiloxane of the following average compositional formula (2);

space="preserve" listing-type="equation">R.sup.2.sub.a H.sub.b SiO.sub.(4-a-b)/2 (

     2)

wherein R² is a substituted or unsubstituted monovalent hydrocarbon group, the R² groups may be identical or different, letters a and b are in the range;

0≦

a<

3 and 0.005≦

b≦

2, and 0.8≦

a+b≦

3.0, having at least two hydrogen atoms attached to silicon atoms in a molecule,

(C) a platinum series catalyst, and

(D) 0.005 to 1 part by weight of a control agent per 100 parts by weight of the organopolysiloxane (component A), wherein said control agent is selected from the group consisting of a triazine of the following general formula (3);

##STR6## wherein R³, R⁴, and R⁵ are independently selected from the group consisting of a peroxy group, monovalent hydrocarbon group, hydroxyl group and hydrogen atom, at least one of R³, R⁴ and R⁵ being a peroxy group, and a sulfide of the following general formula (4);

space="preserve" listing-type="equation">R.sup.6 --(S).sub.m --R.sup.7 (

     4)

wherein each of R⁶ and R⁷ is a monovalent hydrocarbon having at least 3 carbon atoms or a monovalent hydrocarbon group having an ester bond or R⁶ and R⁷ taken together may form a ring structure, and letter m is a positive number of 1 to 3.

2. The silicone rubber composition of claim 1 wherein said sulfide is a monosulfide.

3. The silicone rubber composition of claim 1 which further includes at least one component selected from the group consisting of a vinyl siloxane having a low degree of polymerization, a hydroperoxide, an ethylenically unsaturated isocyanurate, an acetylene alcohol, and a peroxide having a carbon-to-carbon unsaturated bond.

4. The silicone rubber composition of claim 1 which further includes a blowing agent.

5. The silicone rubber composition of claim 1 wherein said sulfide is a monosulfide.

6. The silicone rubber composition of claim 1 which further includes at least one component selected from the group consisting of a vinyl siloxane having a low degree of polymerization, a hydroperoxide, an ethylenically unsaturated isocyanurate, an acetylene alcohol, and a peroxide having a carbon-to-carbon unsaturated bond.

7. The silicone rubber composition of claim 1 which further includes a blowing agent.

8. A silicone rubber composition as in claim 1 wherein R¹ is selected from allyl groups, cycloallyl groups, alkenyl groups and aryl groups, halo-substituted derivatives thereof and cyano-substituted derivatives thereof.

9. A silicone rubber composition as in claim 8 wherein the alkenyl groups within the organopolysiloxanes comprise 0.001 to 20 mol % of the entire R¹ groups.

10. A silicone rubber composition as in claim 1 wherein the organohydrogenpolysiloxane is selected from the group consisting of diorganopolysiloxane end-blocked with a dimethylhydrogensilyl group;

a co-polymer of a dimethyl siloxane unit, a methylhydrogensiloxane unit and a terminal trimethylsiloxy unit;

a low viscosity fluid consisting of dimethylhydrogensiloxane units (H(CH₃)₂ SiO.sub. 1/2 unit) and a SiO₂ unit, 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclosiloxane;

1-hydropropyl-3,5,7-trihydrogen-1,3,5,7-tetramethylcyclotetrasiloxane and 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane.

11. A silicone rubber composition as in claim 1 which comprises a control agent selected from triazine where R³, R⁴, and R⁵ are all peroxy groups.

12. A silicone rubber composition as in claim 11 wherein the peroxy group is selected from those of the formula:

##STR7##

13. A silicone rubber composition as in claim 1 wherein the sulfide is selected from the group consisting of ##STR8##

14. A silicone rubber composition as in claim 1 which contains at least two control agents.

15. A silicone rubber composition as in claim 14 wherein one of the control agents is selected from acetylene alcohols, vinylsiloxanes hydroperoxides and ethylenically unsaturated isocyanurates and peroxides containing a carbon to carbon unsaturated bond.

16. A silicone rubber composition as in claim 15 wherein the amount of one of the control agents falls within the range of about 0.001 to 1 part by weight per 100 parts by weight of the organopolysiloxane (component (A)).