Silicone pressure sensitive adhesive compositions and protective films containing the same
View Patent ↗There is provided herein a silicone pressure sensitive adhesive composition comprising (A) a linear olefinically-functional polyorganosiloxane copolymer gum possessing a degree of polymerization in excess of 3,000; (B) a silicone resin including at least one M H unit and at least one Q unit; and, (C) a hydrosilylation catalyst, wherein the composition is in the substantial absence of low molecular weight siloxane having a degree of polymerization of less than 3,000 and wherein the composition has low peel adhesion to and clean removal from a substrate. There is also provided a protective film including the same as well as a method of making the protective film.
1. A silicone pressure sensitive adhesive composition comprising:
(A) a linear olefinically-functional polyorganosiloxane copolymer gum possessing a degree of polymerization in excess of 3,000;
(B) a silicone resin comprising at least one M H unit of the formula M H =R 1 2 HSiO 1/2 and at least one Q unit of the formula Q=SiO 4/2 , where R 1 is a monovalent hydrocarbon radical of from 1 to 6 carbon atoms and contains from about 50 to about 300 ppm hydride by weight; and
(C) a hydrosilylation catalyst,
wherein the composition comprises less than about 5 weight percent of low molecular weight siloxane having a degree of polymerization of less than about 3,000 and wherein the composition has a peel adhesion to a substrate of from about 1 gf/inch to about 300 gf/inch and leaves less than 5% of silicone residue on the substrate.
2. The silicone pressure sensitive adhesive composition of claim 1 wherein the linear olefinically-functional polyorganosiloxane copolymer gum (A) has a degree of polymerization of from about 4,000 to about 10,000.
3. The silicone pressure sensitive adhesive composition of claim 1 wherein the linear olefinically-functional polyorganosiloxane copolymer gum (A) has a degree of polymerization of from about 5,000 to about 8,000.
4. The silicone pressure sensitive adhesive composition of claim 1 wherein the linear olefinically-functional polyorganosiloxane copolymer gum (A) comprises at least one vinyldimethylsiloxane unit, at least one vinylmethylsiloxane unit, and combinations thereof.
5. The silicone pressure sensitive adhesive composition of claim 1 wherein the linear olefinically-functional polyorganosiloxane copolymer gum (A) is such that from about 0.1 to about 13.0 mole percent of all monomer units in (A) contains an olefinic group.
6. The silicone pressure sensitive adhesive composition of claim 1 wherein the silicone resin (B) further comprises at least one M unit of the formula M H′ =R 1 3 SiO 1/2 , wherein R 1 is as defined.
7. The silicone pressure sensitive adhesive composition of claim 1 wherein the silicone resin (B) further comprises at least one other silicone unit selected from the group consisting of T units of the formula R 1 SiO 3/2 , T H units of the formula HSiO 3/2 , D units of the formula R 1 2 SiO 2/2 , and D H units of the formula R 1 HSiO 2/2 .
8. The silicone pressure sensitive adhesive composition of claim 1 wherein the silicone resin (B) has a viscosity of greater than about 5,000 cps.
9. The silicone pressure sensitive adhesive composition of claim 1 wherein the molar ratio of silyl-hydride in silicone resin (B) to silicon-olefin functionality in linear olefinically-functional polyorganosiloxane copolymer gum (A) is in a range of from about 0.25 to about 20.
10. The silicone pressure sensitive adhesive composition of claim 1 wherein the ratio of the mass of silicone resin (B) to the mass of linear olefinically-functional polyorganosiloxane copolymer gum (A) is in a range of from about 0.1 to about 1.5.
11. The silicone pressure sensitive adhesive composition of claim 1 wherein the hydrosilylation catalyst is a platinum catalyst.
12. The silicone pressure sensitive adhesive composition of claim 1 wherein the hydrosilylation catalyst is a UV activated platinum catalyst.
13. The silicone pressure sensitive adhesive composition of claim 1 wherein the composition is in the absence of low molecular weight siloxane having a degree of polymerization of less than about 3,000.
14. The silicone pressure sensitive adhesive composition of claim 1 wherein the substrate is a glass substrate.
15. The silicone pressure sensitive adhesive composition of claim 1 wherein the removal of the composition from a glass substrate does not leave a silicone residue that is detectable by the naked eye.
16. A protective film comprising a film face stock and a silicone pressure sensitive adhesive composition comprising:
(A) a linear olefinically-functional polyorganosiloxane copolymer gum possessing a degree of polymerization in excess of about 3,000;
(B) a silicone resin comprising at least one M H unit of the formula M H =R 1 2 HSiO 1/2 and at least one Q unit of the formula Q=SiO 4/2 , where R 1 is a monovalent hydrocarbon radical of from 1 to 6 carbon atoms and contains from about 50 to about 300 ppm hydride by weight; and
(C) a hydrosilylation catalyst,
wherein the composition comprises less than about 5 weight percent of low molecular weight siloxane having a degree of polymerization of less than about 3,000.
17. The protective film of claim 16 wherein the film face stock comprises a plastic selected from the group consisting of polyester, poly(meth)acrylate, polycarbonate, polyethylene, polypropylene, polystyrene, polyamide, polyimide, polyphenylene sulfide, polytetrafluoroethylene, polyvinylchloride, polyurethane, tri acetyl cellulose, polyacetal, polynorbornene cycloolefinic resin, epoxy resin, phenolic resin, and combinations thereof.
18. An article comprising the protective film of claim 16 .
19. An article comprising a glass or polymer substrate and the protective film of claim 16 .
20. An electronic display comprising a glass or polymer substrate and the protective film of claim 16 .
21. The electronic display of claim 20 wherein the display is selected from the group consisting of a display in a portable computer, a display in a cell phone, and a display in an electronic device.
22. An electronic component comprising a glass or polymer substrate and the protective film of claim 16 .
23. The article of claim 19 wherein protective film has a peel adhesion to the glass or polymer substrate of from about 1 gf/inch to about 300 gf/inch.
24. A method of making a protective film comprising:
coating at least one surface of a film face stock with a silicone pressure sensitive adhesive composition comprising:
(A) a linear olefinically-functional polyorganosiloxane copolymer gum possessing a degree of polymerization in excess of about 3,000;
(B) a silicone resin comprising at least one M H unit of the formula M H =R 1 2 HSiO 1/2 and at least one Q unit of the formula Q=SiO 4/2 , where R 1 is a monovalent hydrocarbon radical of from 1 to 6 carbon atoms and contains from about 50 to about 300 ppm hydride by weight; and
(C) a hydrosilylation catalyst,
wherein the composition comprises less than about 5 weight percent of low molecular weight siloxane having a degree of polymerization of less than 3,000; and
curing the coated film face stock.
25. A protective film made by the process of claim 24 .
26. A silicone pressure sensitive adhesive composition consisting essentially of:
(A) a linear olefinically-functional polyorganosiloxane copolymer gum possessing a degree of polymerization in excess of 3,000;
(B) a silicone resin comprising at least one M H unit of the formula M H =R 1 2 HSiO 1/2 and at least one Q unit of the formula Q=SiO 4/2 , where R 1 is a monovalent hydrocarbon radical of from 1 to 6 carbon atoms and contains from about 50 to about 300 ppm hydride by weight; and
(C) a hydrosilylation catalyst,
wherein the composition comprises less than about 5 weight percent of low molecular weight siloxane having a degree of polymerization of less than about 3,000 and wherein the composition has a peel adhesion to a substrate of from about 1 gf/inch to about 300 gf/inch and leaves less than 5% of silicone residue on the substrate.