Curable silicone rubber composition for LED packaging
A curable silicone rubber composition is described for an LED enclosure or packaging. A process for preparing the same and the use thereof are also described. Particularly, the compositions can include at least one tackifier component D, which includes: a) a alkenyl or hydrosilyl group including an isocyanurate compound E, and b) an adhesion-imparting ingredient having at least two functional groups selected from the group consisting of alkenyl, epoxy, alkoxy and hydrosilyl groups, which includes of polysiloxane F and optional coupling agents G.
1. A curable silicone rubber composition comprising:
(A) at least one organopolysiloxane A having at least two alkenyl groups bonded to the Si-atom per molecule, or a combination of the at least one organopolysiloxane A with at least one organopolysiloxane resin A′,
(B) at least one organosiloxane B or organosiloxane resin B′ having at least two hydrogen atoms bonded to the same or different Si-atom per molecule, or a mixture of organosiloxane B and organosiloxane resin B′ having at least one hydrogen atom bonded to the same or different Si-atom per molecule,
(C) at least one platinum group metal based catalyst C, and
(D) at least one tackifier component D, which comprises
a) an isocyanurate compound E comprising an alkenyl or a hydrosilyl group, and
b) an adhesion-imparting ingredient which comprises:
a polysiloxane F having at least two distinct functional groups selected from the group consisting of alkenyl, epoxy, alkoxy and hydrosilyl groups, and
optionally a coupling agent G, and
wherein the isocyanurate compound E comprising an alkenyl or a hydrosilyl group in component D) is of the following formula III:
in which R 1 represents, identically or differently, C 1-12 -alkyl, C 2-12 -alkenyl, C 6-20 -aryl, -aralkyl or -alkaryl, wherein said alkyl, alkenyl, aryl, aralkyl or alkaryl groups are optionally substituted with oxiranyl, and linear or cyclic polysiloxane groups, provided that at least one group R 1 comprises an alkenyl or hydrosilyl group.
2. The composition according to claim 1 , wherein R 1 independently from each other represents methyl, ethyl, propyl, butyl, vinyl, allyl, glycidyl, or tetramethyl cyclotetrasiloxane groups.
3. The composition according to claim 1 , wherein the isocyanurate compound E is the isocyanurate of formula III wherein one or two of groups R 1 represent allyl and the other comprises an epoxy moiety, or the isocyanurate compound E is triallyl isocyanurate.
4. The composition according to claim 1 , wherein the organopolysiloxane resin A′ comprises:
a) at least two different siloxane units selected from the group consisting of siloxane unit M of formula R 3 SiO 1/2 , siloxane unit D of formula R 2 SiO 2/2 , siloxane unit T of formula RSiO 3/2 and siloxane unit Q of formula SiO 4/2 , in which R denotes a monovalent hydrocarbyl group having 1 to 20 C atoms,
b) provided that at least one of these siloxane units is siloxane unit T or Q and at least one of siloxane units M, D and T comprises an alkenyl group.
5. The composition according to claim 1 , wherein the organopolysiloxane resin B′ comprises:
a) at least two different siloxane units selected from the group consisting of siloxane unit M of formula R 3 SiO 1/2 , siloxane unit D of formula R 2 SiO 2/2 , siloxane unit T of formula RSiO 3/2 and siloxane unit Q of formula SiO 4/2 , in which R denotes a monovalent hydrocarbyl group having 1 to 20 C atoms,
b) provided that at least one of these siloxane units is siloxane unit T or Q and at least one of siloxane units M, D and T comprises a Si—H group.
6. The composition according to claim 1 , wherein the molar ratio of Si—H group to alkenyl group in the composition is in a range of from 0.7 to 4.
7. The composition according to claim 1 , wherein component D is present in an amount ranging from 0.005% to 30%, relative to the total weight of individual components of the composition.
8. The composition according to claim 7 , wherein the component D is present in an amount ranging from 0.005 to 15% relative to the total weight of individual components of the composition.
9. The composition according to claim 1 , wherein the composition comprises no metallic condensation catalysts.
10. The composition according to claim 9 , wherein the metallic condensation catalysts include aluminium chelating compound catalysts.
11. The composition according to claim 1 , wherein polysiloxane F of the tackifier component D comprises a siloxy unit of formula (I.1) and siloxy unit selected from at least one of formulae (I.2), (I.3), (I.4) and (I.5):
Z
c
′
2
SiO
4
-
c
′
2
(
I
.1
)
Y
a
′
Z
b
′
1
SiO
4
-
(
a
′
+
b
′
)
2
(
I
.2
)
Y
f
′
′
Z
g
′
1
SiO
4
-
(
f
′
+
g
′
)
2
(
I
.3
)
Y
h
′
″
Z
i
′
1
SiO
4
-
(
h
′
+
i
′
)
2
(
I
.4
)
H
d
′
Z
e
′
3
SiO
4
-
(
d
′
+
e
′
)
2
(
I
.5
)
in which
a′=1 or 2, b′=0, 1 or 2, and a′+b′=1, 2 or 3,
c′=1, 2 or 3,
d′=1 or 2, e′=0, 1 or 2 and d′+e′=1, 2 or 3,
f′=1 or 2, g′=0, 1 or 2 and f′+g′=1, 2 or 3,
h′=1 or 2, i′=0, 1 or 2 and h′+i′=1, 2 or 3,
Y independently of each other represents a hydrocarbyl group with an epoxy functionality which optionally comprises one or more heteroatoms,
Y′ independently of each other represents an alkoxy group,
Y″ independently of each other represents a C 2-12 alkenyl,
Z 1 , Z 2 , Z 3 , identically or differently, represent a monovalent hydrocarbyl group having 1 to 30, which optionally comprises one or more heteroatoms.
12. The composition according to claim 11 , wherein when Y comprises a heteroatom, the heteroatom is oxygen.
13. The composition according to claim 11 , wherein Y has 2 to 20 carbon atoms.
14. The composition according to claim 11 , wherein Y is selected from the group consisting of alkyl glycidyl ether, linear, branched and/or cyclic epoxy alkyl, linear, branched and/or cyclic epoxy alkenyl and glycidyl esters of carboxylic acids.
15. The composition according to claim 11 , wherein Y′ is an alkoxy having 1 to 12 carbon atoms.
16. The composition according to claim 11 , wherein Y′ has 1 to 6 carbon atoms.
17. The composition according to claim 11 , wherein Y′ is a methoxy or ethoxy group.
18. The composition according to claim 11 , wherein Y″ is a C 2-6 alkenyl.
19. The composition according to claim 11 , wherein Y″ is a vinyl or allyl.
20. The composition according to claim 11 , wherein Z 1 , Z 2 , and Z 3 have 1 to 12 carbon atoms.
21. The composition according to claim 11 , wherein Z 1 , Z 2 , and Z 3 represent a C 1-8 alkyl group.
22. The composition according to claim 11 , wherein Z 1 , Z 2 , and Z 3 represent an alkyl optionally substituted by at least one halogen atom.
23. The composition according to claim 11 , wherein Z 1 , Z 2 , and Z 3 are an aryl group.
24. The composition according to claim 23 , wherein the aryl group is a C 6-20 aryl group.
25. The composition according to claim 1 , wherein the tackifier component D comprises the isocyanurate compound E and the adhesion-imparting ingredient.
26. The composition according to claim 1 , wherein when the composition comprises the coupling agent G, the amount of the coupling agent does not exceed 80% by weight, in the adhesion-imparting ingredient.
27. The composition according to claim 26 , wherein the amount of the coupling agent does not exceed 60% by weight in the adhesion-imparting ingredient.
28. The composition according to claim 27 , wherein the amount of the coupling agent does not exceed 30% by weight in the adhesion-imparting ingredient.
29. A process of preparing the composition according to claim 1 , that the process comprising mixing together the individual components A to D and optional other additives.
30. A silicone rubber, obtained by curing the composition according to claim 1 .
31. An LED enclosure material, the enclosure material comprising the composition according to claim 1 .
32. A method of improving adhesion of a curable silicone rubber composition, the method comprising preparing the silicone rubber composition with the tackifier component D according to claim 1 , wherein the silicone rubber composition is prepared for effective use in an LED enclosure without using a metallic condensation catalyst.