Curable siloxane composition with modified surface properties
View Patent ↗The present invention relates to new curable siloxane compositions, and their use for the manufacture of cured products thereof having modified release properties. The modified release forces are achieved by incorporating a selected pressure sensitive adhesive additive.
1. A curable siloxane composition comprising:
(a) 100 parts by weight of component A), where component A) is at least one reactive alkenyl-containing polyorganosiloxane polymer, wherein the content of the T- and Q-units if present does not exceed 10 mol-% of all siloxy units,
(b) 0 to 20 parts by weight of component B), wherein component B) is at least one siloxane cross-linking agent,
(c) 1 to 10,000 ppmw of component C), based on the total weight of components A), B), C), D), E) and F), wherein component C) is a catalyst,
(d) 0.01 to 10 parts by weight of component D), where component D) is at least one organosilicone pressure sensitive adhesive, wherein the content of the total of T- and Q-units is more than 10 mol-% of all siloxy units, the content of D-units is more than 10 mol-% of all siloxy units, and at least 90 mol-% of the organo groups in the organosilicone compound are alkyl groups, wherein D) is selected from non-reactive polyorganosiloxanes with respect to components A) and B),
(e) optionally auxiliary additives E), and
(f) optionally solvents F).
2. The curable siloxane composition according to claim 1 , wherein component A) is selected from alkenyl-containing polyorganosiloxanes, component B) is selected from SiH-containing polyorganosiloxanes and SiH-containing organosilanes, and component C) is selected from organometallic hydrosilylation catalysts.
3. The curable siloxane composition according to claim 2 , wherein the component D) is selected from a polyorganosiloxane which is a reaction product between a resinous prepolymer comprising at least M- and at least Q-units and a gumlike prepolymer comprising at least D-units.
4. The curable siloxane composition according to claim 2 , wherein in component D) the molar ratio of D:Q is greater than one.
5. The curable siloxane composition according to claim 1 , wherein the component D) is selected from a polyorganosiloxane which is a reaction product between a resinous prepolymer comprising at least M- and at least Q-units and a gumlike prepolymer comprising at least D-units.
6. The curable siloxane composition according to claim 5 , wherein in component D) the molar ratio of D:Q is greater than one.
7. The curable siloxane composition according to claim 1 , wherein in component D) the molar ratio of D:Q is greater than one.
8. The curable siloxane composition according to claim 1 , wherein component D) is selected from polyorganosiloxanes comprising at least one M unit at least one Q unit, and at least one D unit, wherein the ratio of the siloxane units D to Q is greater than 1.
9. Curable siloxane composition according to claim 1 , wherein component D) is selected from polyorganosiloxane block copolymers.
10. A multi-layered product comprising:
(a) a release sheet comprising
(i) a carrier and a release film and
(ii) an adhesive sheet comprising
a. a carrier and
b. an adhesive film, wherein
said release film is formed of the composition of claim 9 , and wherein said release film is in contact with the adhesive film.
11. A cured siloxane composition, obtained by curing the composition according to claim 1 .
12. A substrate, comprising the composition according to claim 11 on the surface thereof.
13. A process for coating a substrate, comprising
(a) applying the composition according to claim 1 onto the surface of the substrate, and
(b) curing said composition on the surface of the substrate.
14. A process of coating a substrate, comprising applying to the substrate the composition of claim 1 .
15. A process of preparing release films, comprising applying to a substrate to be released, the composition of claim 1 .