UV curable silicone rubber compositions

• US 4,675,346 A
• Filed: 01/16/1984
• Issued: 06/23/1987
• Est. Priority Date: 06/20/1983
• Status: Expired due to Term

• Current Assignee: Locite Corporation
• Original Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Inventors: Lin, Samuel Q. S., Nakos, Steven T.
• Primary Examiner(s): Bleutge, John C.
• Assistant Examiner(s): Koeckert, A. H.
• Application Number:
  US06/571,036
• Time in Patent Office: 1,254 Days
• Field of Search: 204/159.13, 522/39, 522/34, 522/40, 522/43, 522/46, 522/78, 522/83, 522/99
• US Class Current: 522/39
• CPC Class Codes: C08F 2/50 with sensitising agents
• CPC Class Codes: C08F 299/00 Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
• CPC Class Codes: C08F 299/08 from polysiloxanes
• CPC Class Codes: C08G 77/14 containing silicon bound to oxygen-containing groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/38 Polysiloxanes modified by chemical after-treatment C08G77/045 takes precedence
• CPC Class Codes: C08J 2383/04 Polysiloxanes
• CPC Class Codes: C08J 3/243 Two or more independent types of crosslinking for one or more polymers
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08K 5/0025 Crosslinking or vulcanising agents; including accelerators
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C08L 2666/54 Inorganic substances
• CPC Class Codes: C08L 83/06 containing silicon bound to oxygen-containing groups C08L83/12 takes precedence
• CPC Class Codes: C09J 183/06 containing silicon bound to oxygen-containing groups C09J183/12 takes precedence
• CPC Class Codes: H05K 3/285 Permanent coating compositions

Abstract

Compositions of (a) a silicone resin characterized by an intermediate region free of acrylic groups, at least 150 siloxane units long, and terminal acrylic groups; (b) at least 10% of a fumed silica filler; and (c) a photoinitiator, can be cured by UV irradiation to tough elastomeric materials useful in adhesive and sealant applications.

Claims

1. A silicone composition curable by UV irradiation to an elastomer comprising:

(a) At least 56% by weight of a silicone resin or mixture of silicone resins represented by the formula;

##STR4## where R¹ is H or alkyl, the R² groups are divalent hydrocarbon or hydrocarbonoxy groups, the R³ groups are the same or different alkyl, substituted alkyl, aryl, substituted aryl, alkoxy, or aryloxy groups;

the R⁴ groups are the same or different alkyl, halo substituted alkyl, or aryl groups and n is an integer between about 150 and 700;

(b) At least about 10% of a fumed silica filler; and

(c) A photoinitiator.

2. A composition as in claim 1 wherein the R⁴ groups are all methyl.

3. A composition as in claim 1 wherein said fumed silica filler is a hydrophobic silica.

4. A composition as in claim 1 wherein said fumed silica filler is present at a level of about 20% or more by weight.

5. A composition as in claim 4 wherein said fumed silica filler is a dimethyldichlorosilane or hexamethyldisilazane treated silica.

6. A composition as in claim 1 curable to an elastomer characterized by a tensile strength of at least 200 psi and a Shore A hardness of at least 20.

7. A composition as in claim 6 further characterized by a tear resistance of the cured elastomer in excess of 125 lb./in.

8. A composition as in claim 7 wherein the cured elastomer tear resistance is 170 lb./in. or more.

9. A composition as in claim 1 wherein the photoinitiator is present in the range of 0.1%-5% by weight.

10. A composition as in claim 1 wherein the photoinitiator is selected from benzoin, substituted benzoins, benzophenone, Michler'"'"'s Ketone, and dialkoxyacetophenones.

11. A composition as in claim 1 wherein the photoinitiator is polymer bound.

12. A composition as in claim 1 wherein R¹ is H or CH₃, and R² is propylene or propenylene.

13. A composition as in claim 12 wherein R³ and R⁴ are methyl.

14. A cured composition as in claim 1.

15. A cured composition as in claim 4.

16. A cured composition as in claim 6.

17. A cured composition as in claim 7.

18. A cured composition as in claim 13.

19. A silicone composition curable to an elastomer comprising:

(a) At least 56% by weight of a silicone resin or mixture of resins represented by the formula;

##STR5## where R¹ is H or alkyl, the R² groups are divalent hydrocarbon or hydrocarbonoxy groups, the R³ groups are the same or different alkyl, substituted alkyl, aryl, substituted aryl, alkoxy, or aryloxy groups;

the R⁴ groups are the same or different alkyl, halo substituted alkyl, or aryl groups and n is an integer between about 150 and 700;

(b) At least about 10% of a fumed silica filler; and

(c) A free radical initiator.