Dual curing silicone compositions

• US 20040116547A1
• Filed: 09/30/2003
• Published: 06/17/2004
• Est. Priority Date: 08/21/1997
• Status: Abandoned Application

• Current Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Original Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Inventors: Bennington, Lester D.
• Application Number:
  US10/674,659
• Publication Number:
  US 20040116547A1
• Time in Patent Office: Days
• US Class Current: 522/29
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• 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 83/06 containing silicon bound to oxygen-containing groups C08L83/12 takes precedence
• CPC Class Codes: C09D 183/06 containing silicon bound to oxygen-containing groups C09D183/12 takes precedence
• CPC Class Codes: H05K 3/287 Photosensitive compositions

Abstract

The present invention relates to dual curing silicone compositions which are capable of crosslinking when subjected to actinic radiation and/or heat. The compositions contain a reactive organopolysiloxane having a function group selected from the group consisting of (meth)acrylate, carboxylate, maleate, cinnamate and combinations thereof; a silicon hydride crosslinker; an organo-metallic hydrosilation catalyst; and a photoinitiator. These compositions can be cured to relatively thick films using UV light due to the presence of the specific olefinic unsaturated groups, and can also be partially or fully cured at room temperature or under thermal exposure. These compositions are particularly useful as conformal coatings, and in particular as coatings in electronic applications.

Claims

1. A dual curing silicone composition comprising:

a) a reactive polyorganosiloxane having the formula;

 

wherein R¹, R², R³ and R⁵ can be the same or different and are substituted or unsubstituted hydrocarbon or hydrocarbonoxy radicals from C_1-20, provided that at least one of these R groups is an ethylenically unsaturated carboxylate, and provided that the reactive functional group is not directly bonded to a silicon atom, wherein n is from 1 to 1,200;

b) a silicon hydride crosslinker;

c) an organo-metallic hydrosilation catalyst; and

d) a photoinitiator; and

2. The composition of claim 1, wherein said reactive polyorganosiloxane has the formula:

wherein R¹, R², R³ and R⁵ can be the same or different and are substituted or unsubstituted hydrocarbon or hydrocarbonoxy radicals from C_1-20, provided that at least one of these R groups are selected from the reactive functional groups consisting of (meth)acrylate, carboxylate, maleate, cinnamate and combinations thereof, and provided that the reactive functional group is not directly bonded to a silicon atom.

3. The composition of claim 1 wherein said polyorganosiloxane has the formula:

4. The composition of claim 3, wherein the composition further includes a moisture curing catalyst.

5. The composition of claim 1, wherein the reactive polyorganosiloxane is present in the range of about 50% to about 95% by weight of said composition.

6. The composition of claim 1, wherein the silicon hydride crosslinker has the formula:

7. The composition of claim 1, wherein the silicon hydride crosslinker is present in amounts of about 1% to about 10% by weight of said composition.

8. The composition of claim 1, wherein the organo-metallic hydrosilation catalyst is selected from the group consisting of organoplatinum, organorhodium, organoplatinum complexes, organorhodium complexes, platinum alcoholates and combinations thereof.

9. The composition of claim 1, wherein the organo-metallic hydrosilation catalyst is present in amounts of about 0.025% to about 1.0% by weight of said composition.

10. The composition of claim 1, wherein the photoinitiator is selected from a group consisting of benzophenones, acetophenones, xanthones, benoin, alkylesters of benzoin and mixtures thereof.

11. The composition of claim 1, wherein the photoinitiator is present in amounts of about 1% to about 10% by weight of said composition.

12. The composition of claim 1, further including at least one hydrolyzable group.

13. The composition of claim 12, wherein the hydrolyzable group is selected from the group consisting of alkoxy, aryloxy alkaryloxy, aryalkoxy, amino, hydroxyl and combinations thereof.

14. The composition of claim 12, which further includes a moisture curing catalyst.

18. The composition of claim 1 wherein said carboxylate is selected from the group consisting of (meth)acrylate, maleate, cinnamate and combinations thereof.

15. A conformal coating composition formed by the reaction product of:

a) a reactive polyorganosiloxane having the formula;

 

wherein R¹, R², R³ and R⁵ can be the same or different and are substituted or unsubstituted hydrocarbon or hydrocarbonoxy radicals from C_1-20, provided that at least one of these R groups is a carboxylate, and provided that the reactive functional group is not directly bonded to a silicon atom;

b) a silicon hydride crosslinker;

c) an organo-metallic hydrosilation catalyst; and

d) a photoinitiator.

19. The conformal coating composition of claim 15 wherein said carboxylate is selected from the group consisting of (meth)acrylate, maleate, cinnamate and combinations thereof.

16. A method of forming a conformal coating comprising the steps of:

1) applying a dual curing silicone composition to a substrate comprising;

a) a reactive polyorganosiloxane having the formula;

 

wherein R¹, R², R³ and R⁵ can be the same or different and are substituted or unsubstituted hydrocarbon or hydrocarbonoxy radicals from C_1-20, provided that at least one of these R groups is an ethylenically unsaturated carboxylate, and provided that the reactive functional group is not directly bonded to a silicon atom;

b) a silicon hydride crosslinker;

c) an organo-metallic hydrosilation catalyst; and

d) a photoinitiator; and

2) exposing said composition to a curingly effective amount of actinic radiation and/or heat to effectuate a cured conformal coating.

20. The method of claim 16 wherein said carboxylate is selected from the group consisting of (meth)acrylate, maleate, cinnamate and combinations thereof.

17. A method of making a dual curing silicone composition comprising the steps of:

combining in admixture;

a) a reactive polyorganosiloxane having the formula;

wherein R¹, R², R³ and R⁵ can be the same or different and are substituted or unsubstituted hydrocarbon or hydrocarbonoxy radicals from C_1-20, provided that at least one of these R groups is an ethylenically unsaturated carboxylate, and provided that the reactive functional group is not directly bonded to a silicon atom;

b) a silicon hydride crosslinker;

c) an organo-metallic hydrosilation catalyst; and

d) a photoinitiator.

21. The method according to claim 17 wherein said carboxylate is selected from the group consisting of (meth)acrylate, maleate, cinnamate and combinations thereof.