Granted Patent B2

US 9,834,679 · App. 14/814,965 · Granted Dec 5, 2017

Abstract

Claims (31)

1. A curable composition comprising:

(a) a mercapto-functional siloxane;

(b) a siloxane comprising an unsaturated hydrocarbon group;

(c) a photoinitiator; and

(d) an antioxidant compound comprising a hindered phenol; wherein (a) and (b) are provided such that the composition has a molar equivalent ratio of mercapto groups to unsaturated groups of about 2.5:1 to about 6:1.

2. The curable composition of claim 1 , wherein the mercapto-functional siloxane is a siloxane of the formula:

M 1 a M 2 b D 1 c D 2 d T 1 e T 2 f Q g   (1)

where the M-units are of the formula R 1 R 2 R 3 SiO 1/2 ; the D-units are of the formula: R 4 R 5 SiO 2/2 ; the T-units have three Si—O bonds are of the formula: R 6 SiO 3/2 ; the Q-units are of the formula SiO 4/2 ; R 1 -R 6 are independently chosen from hydrogen, a hydroxyl, a linear or branched alkyl group, an alcohol, a linear or branched alkoxy group, an aryl group, an alkylvinyl group, an amide, an amino-group, an acryloyl group, a carbonyl group, a silyloxy group, an isocyanyl group, a mercapto group, an epoxy-containing group, where one or more of R 1 -R 6 is a mercapto group; a is from 0-1000, b is from 0-1000; c is from 0-500; d is from 0-500; e is from 0-100; f is from 0-100; and g is from 0 to 200, where at least two subscripts on any particular embodiment are positive integers.

3. The curable composition of claim 2 , wherein the mercapto group is of the formula —(CH 2 ) h SH, where h is 0-10.

4. The curable composition of claim 3 , wherein the mercapto group is chosen from mercaptomethyl, 2-mercaptoethyl, 3-mercaptopropyl, 4-mercaptobutyl, or a combination of two or more thereof.

5. The curable composition of claim 1 , wherein the siloxane (b) is of the formula:

M 3 i M 4 j D 3 k D 4 l T 3 m T 4 n Q o   (2)

where the M-units are of the formula R 7 R 8 R 9 SiO 1/2 ; the D-units are of the formula R 10 R 11 SiO 2/2 ; the T-units have three Si—O bonds are of the formula R 12 SiO 3/2 ; the Q-units are of the formula SiO 4/2 ; R 7 -R 12 are independently chosen from hydrogen, a hydroxyl, a linear or branched alkyl group, an alcohol, a linear or branched alkoxy group, an aryl group, an alkylvinyl group, an amide, an amino group, an acryloyl group, a carbonyl groups, a silyloxy group, an isocyanyl group, a mercapto group, an epoxy-containing group, where one or more of R 7 -R 12 comprises an unsaturated group; i is from 0-1000, j is from 0-1000, k is from 0-500, l is from 0-100, m is from 0-100, n is from 0-100, and o is from 0 to 200, where at least two subscripts on any particular embodiment are positive integers.

6. The curable composition of claim 5 , wherein the unsaturated group comprises an alkenyl group of the formula CH 2 ═CH—R 13 x — where R 13 is a C1-C20 alkyl, a C1-C20 branched alkyl, a C1-C10 cyclic alkyl, or a C6-C10 aryl group.

7. The curable composition of claim 5 , wherein the unsaturated group is chosen from vinyl, allyl, styryl, butenyl, pentenyl, hexenyl, or a combination of two or more thereof.

8. The curable composition of claim 1 , wherein the photoinitiator is an acylphosphine compound.

9. The curable composition of claim 8 , wherein the acylphosphine compound is chosen from a mono-acylphosphine compound, a bis-acylphosphine compound, or a combination of two or more thereof.

10. The curable composition of claim 8 , wherein the acylphosphine compound is chosen from diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and bis(2,6-di-methoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

11. The curable composition of claim 1 , wherein the hindered phenol is chosen from 2,6-di-t-butyl-p-cresol; 2-t-butyl-4-methoxyphenol; 3-t-butyl-4-methoxyphenol; 2,6-t-butyl-4-ethylphenol; 2,2′-methylene-bis(4-methyl-6-t-butylphenol); 4,4′-thiobis(3-methyl-6-t-butylphenol); 4,4′-butylidene-bis(3-methyl-6-t-butylphenol); 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane; 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene; tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane; bis[3,3′-bis(4′-hydroxy-3-t-butylphenyl)butyric acid glycol ester; tocopherol; or a combination of two or more thereof.

12. The curable composition of claim 1 comprising the photoinitiator in an amount of from about 200 ppm to about 1500 ppm.

13. The curable composition of claim 1 comprising the hindered phenol in an amount of from about 200 ppm to about 2000 ppm.

14. A cured article formed from a curable composition comprising:

(a) a mercapto-functional siloxane comprising;

(b) a siloxane comprising an unsaturated hydrocarbon group;

(c) a photoinitiator; and

(d) an antioxidant compound comprising a hindered phenol; wherein (a) and (b) are provided such that the composition has a molar equivalent ratio of mercapto groups to unsaturated groups of about 2.5:1 to about 6:1.

15. The cured article of claim 14 , wherein the cured article has a refractive index of from about 1.41 to about 1.53.

16. The cured article of claim 15 , wherein the cured article has a yellowing index of from about 0 to about 10 after ageing for 350 hours.

17. The cured article of claim 15 , wherein the article has a transparency of about 85% or greater.

18. A method of forming a cured article comprising exposing a curable composition to UV light, visible light, or a combination of two or more thereof, the composition comprising: (a) a mercapto-functional siloxane; (b) a siloxane comprising an unsaturated hydrocarbon group; (c) a photoinitiator; and (d) an antioxidant compound comprising a hindered phenol, wherein (a) and (b) are provided such that the composition has a molar equivalent ratio of mercapto groups to unsaturated groups of about 2.5:1 to about 6:1.

19. The method of claim 18 further comprising heating the curable composition by exposing the composition to a temperature of from about 70° C. to about 150° C.

Assignments (10)