Dual curing silicone, method of preparing same and dielectric soft-gel compositions thereof

• US 4,528,081 A
• Filed: 10/03/1983
• Issued: 07/09/1985
• Est. Priority Date: 10/03/1983
• Status: Expired due to Term

• Current Assignee: Samuel Q.S. Lin
• Original Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Inventors: Nakos, Steven T., Lien, Qcheng S.
• Primary Examiner(s): Marquis, Melvyn I.
• Application Number:
  US06/538,624
• Time in Patent Office: 645 Days
• Field of Search: 204/159.13, 528/34, 528/12
• US Class Current: 522/39
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08L 83/06 containing silicon bound to oxygen-containing groups C08L83/12 takes precedence
• CPC Class Codes: H05K 3/285 Permanent coating compositions

Abstract

Novel dual curing silicones are terminated with acrylic functional dialkoxy or diaryloxy silyl groups. They are prepared by condensation of a silanol terminated silicone with a silane represented by the formula ##STR1## where R³ is alkyl or aryl, R⁴ is H or C_1-5 alkyl and R⁵ is alkylene, the ratio of silane to silanol silicone being between about 2.1 and 6.1.

Compositions of the novel silicones with moisture cure catalysts, photoinitiators and optionally up to 70% trimethyl silyl terminated silicone oils, are both moisture and UV curable and produce soft gel or rubbery cured materials suitable for electronic potting applications.

Claims

1. A composition capable of curing by both moisture cure and UV cure mechanisms, the composition comprising:

(a) 30-100 parts by weight of a reactive polyorganosiloxane terminated with acrylic functional dialkoxy- or diaryloxy-silyl groups and containing about 0.1-5% of a silicone moisture curing catalyst;

(b) 0-70 parts by weight of a trimethylsilyl terminated silicone oil; and

(c) an effective amount of a photosensitizer, said photosensitizer present either as photosensitive groups bound to said reactive polyorganosiloxane or as a separate ingredient in admixture with components (a) and (b) above,

wherein the reactive polyorganosiloxane comprises the reaction product of a silanol terminated silicone represented by the formula;

##STR5## wherein R¹ and R² are organo groups, no more than 2% of which are crosslinkable under UV or moisture cure conditions, and n is an integer, said silanol having a viscosity of between about 600 and 20,000 cst, with an acrylic functional trialkoxy- or triaryloxysilane of the formula;

##STR6## wherein R³ are the same or different alkyl or aryl groups;

R⁴ is H or C_1-5 alkyl and R⁵ is alkylene, in the presence of a condensation catalyst, the mole ratio of said silane to said silanol being between 2;

1 and 6;

1, and the reaction including removing substantially all of the theoretical amount of R³ OH produced by the reaction.

2. A composition as in claim 1 wherein said photosensitizer is selected from substituted or unsubstituted benzoin, benzophenone, dialkoxybenzophenones, Michlers'"'"' ketone and diethoxyacetophenone.

3. A composition as in claim 1 containing a said trimethylsilyl terminated silicone oil, the silicone oil having a viscosity of between 100 and 5,000 cps.

4. A composition as in claim 1 having between 30 and 70% of said silicone oil.

5. A composition as in claim 1 wherein said moisture cure catalyst in an orthotitanate catalyst.

6. A composition as in claim 1 wherein said reactive polyorganosiloxane has a molecular weight of between about 12,000 and 50,000.

7. A composition as in claim 1 further comprising an adhesion promoter.

8. A composition as in claim 1 further comprising an ion trapping compound.

9. A composition as in claim 1 wherein said R¹ or R² organo groups on said silanol terminated silicone include photosensitizing groups, said groups comprising said photosensitizer ingredient c.

10. A composition as in claim 9 wherein said R¹ or R² photosensitizing groups comprise benzoin or benzoin ether groups.

11. A composition as in claim 1 wherein said silanol terminated silicone has a viscosity of between about 600 cst and 4000 cst.