Crosslinking of (meth) acryloxyalkenylene functional siloxane prepolymers

• US 4,952,711 A
• Filed: 05/25/1989
• Issued: 08/28/1990
• Est. Priority Date: 05/25/1989
• Status: Expired due to Fees

• Current Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Original Assignee: Loctite Corporation (Henkel AG & Co KGaA)
• Inventors: Jacobine, Anthony F., Nakos, Steven T.
• Primary Examiner(s): Marquis, Melvyn I.
• Application Number:
  US07/357,053
• Time in Patent Office: 460 Days
• Field of Search: 522/99, 522/24, 522/30, 522/7, 522/40, 522/46, 522/44, 522/62
• US Class Current: 522/99
• 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

Abstract

A composition curable to a solid crosslinked polyorganosiloxane comprises:

(a) an acrylic functional silicone prepolymer having a plurality of acrylic groups of the formula: ##STR1## bound to silicon atoms thereof, where R is H or methyl, and R¹ is a divalent olefinically unsaturated hydrocarbon group,

(b) a silicone prepolymer having a plurality of organothiol groups thereon, and

(c) an effective amount of a thiol-ene cure catalyst.

Particularly preferred formulations are photoinitiated formulations employing alkylthiol functional silicones in which the total number of thiol groups is between 0.5 and 1.5 times the total number of ene groups counting both the acrylic and the linking group R¹ as ene groups.

Claims

1. A composition cureable to a solid crosslinked polyorganosiloxane comprising:

(a) an acrylic functional silicone prepolymer having a plurality of acrylic groups of the formula;

##STR9## bound to silicon atoms thereof, where R is H or methyl, and R¹ is a divalent olefinically unsaturated hydrocarbon group,

(b) a silicon prepolymer having a plurality of organothiol groups thereon, and

(c) an effective amount thiol-ene cure catalyst.

2. A composition as in claim 1 wherein R¹ is a C₃ -C₁₅ olefinically unsaturated hydrocarbon group.

3. A composition as in claim 1 wherein R¹ is propenylene.

4. A composition as in claim 1 wherein at least 20% on an equivalent basis of the organothiol functional silicone prepolymer comprises a compound of the formula:

##STR10## where R³ is lower alkylene, x is 3-10, and y is 25-50.

5. A composition as in claim 4 wherein the organothiol functional silicone prepolymer further comprises a compound of the formula:

##STR11## where m is between 1 and 3, and n is 3-15.

6. A composition as in claim 1 wherein the thiol-ene cure catalyst is a free radical photointiator.

7. A composition as in claim 1 wherein the acrylic functional silicone prepolymer comprises a compound of the formula:

##STR12## where b is 1 to 3, c is 0 to 2 and b+c=3, q is from 100-1500 and R² is hydrocarbyl or halohydrocarbyl.

8. A composition as in claim 7 wherein b is 1, c is 2 and R² is methyl.

9. A composition as in claim 4 wherein the acrylic functional silicone prepolymer is a compound of the formula:

##STR13## where R² is methyl, b is 1, c is 2 and q is from 100-1500.

10. A composition as in claim 9 wherein q is 250-750, x is 4-7, and y is 28-36.

11. A composition as in claim 10 wherein the number of ene groups and the number of thiol groups are approximately equal.

12. A composition as in claim 1 further comprising between 1% and 60% of a fumed silica filler.

13. A composition as in claim 12 wherein the silica is treated to render it hydrophobic.

14. A composition as in claim 3 wherein the propenylene groups are predominantly the exo isomer having the formula ##STR14##

15. A composition as in claim 14 wherein the said exo isomer comprises at least 70% of the propenylene groups.

16. A composition as in claim 1 wherein the ratio of ene groups to thiol groups is between 0.5:

1 and 5;

1.

17. A composition as in claim 16 wherein the number of ene groups and the number of thiol groups are approximately equal.

18. A cured product of the composition of claim 1.

19. A cured product of the composition of claim 9.