Silicone elastomer composition
First Claim
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1. A curable high tear strength, low hardness silicone elastomer-forming composition comprising:
- (A) at least two organopolysiloxanes each independently containing at least two silicon-bonded alkenyl groups per molecule, provided said at least two organopolysiloxanes (A) contain at least one substantially straight chain organopolysiloxane and at least one substantially resinous organopolysiloxane;
(B) at least two organohydrogenpolysiloxanes each independently containing at least two silicon-bonded hydrogen atoms per molecule, provided said at least two organohydrogenpolysiloxanes (B) contain at least one substantially straight chain organohydrogenpolysiloxane and at least one substantially resinous organohydrogenpolysiloxane said at least two organohydrogenpolysiloxanes (B) being used in an amount such that the mole ratio of total amount of silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to silicon-bonded alkenyl groups contained in at least two organopolysiloxanes (A) is of from about 1.3 to about 2.2;
(C) filler in an amount of from about 15 to about 45 parts per hundred of polyorganosiloxane (A);
(D) catalyst; and
,(E) inhibitor, and where combined (A)-(E) comprises a curable high tear strength, low hardness silicone elastomer-forming composition, wherein when said composition is cured it has a Shore A hardness of less than about 35.
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Abstract
High tear strength, low hardness silicone elastomer-forming composition is provided using a unique combination(s) of polyorganosiloxanes and organohydrogenpolysiloxanes, where the polyorganosiloxanes and the organohydrogenpolysiloxanes contain both straight-chain and resinous polyorganosiloxanes.
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Citations
31 Claims
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1. A curable high tear strength, low hardness silicone elastomer-forming composition comprising:
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(A) at least two organopolysiloxanes each independently containing at least two silicon-bonded alkenyl groups per molecule, provided said at least two organopolysiloxanes (A) contain at least one substantially straight chain organopolysiloxane and at least one substantially resinous organopolysiloxane; (B) at least two organohydrogenpolysiloxanes each independently containing at least two silicon-bonded hydrogen atoms per molecule, provided said at least two organohydrogenpolysiloxanes (B) contain at least one substantially straight chain organohydrogenpolysiloxane and at least one substantially resinous organohydrogenpolysiloxane said at least two organohydrogenpolysiloxanes (B) being used in an amount such that the mole ratio of total amount of silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to silicon-bonded alkenyl groups contained in at least two organopolysiloxanes (A) is of from about 1.3 to about 2.2; (C) filler in an amount of from about 15 to about 45 parts per hundred of polyorganosiloxane (A); (D) catalyst; and
,(E) inhibitor, and where combined (A)-(E) comprises a curable high tear strength, low hardness silicone elastomer-forming composition, wherein when said composition is cured it has a Shore A hardness of less than about 35. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A curable high tear strength, low hardness silicone elastomer-forming composition comprising:
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(A) at least two organopolysiloxanes each independently containing at least two silicon-bonded alkenyl groups per molecule, wherein at least two organopolysiloxanes (A) is a combination of (A-i) substantially straight chain vinyl organopolysiloxane having a viscosity of from about 50,000 to about 80,000 centipoise at 25 degrees celsius, and being present in an amount of from about 45 to about 50 weight percent;
(A-ii) substantially straight chain vinyl organopolysiloxane having a viscosity of from about 20,000 to about 45,000 centipoise at 25 degrees celsius, and being present in an amount of from about 20 to about 25 weight percent;
(A-iii) substantially resinous vinyl organopolysiloxane having a viscosity of from about 15 to about 250 centipoise at 25 degrees celsius, and being present in an amount of from about 1.5 to about 2.5 weight percent;(B) at least two organohydrogenpolysiloxanes each independently containing at least two silicon-bonded hydrogen atoms per molecule, wherein at least two organohydrogenpolysiloxanes (B) is a combination of(B-i) substantially straight chain organohydrogenpolysiloxane where (B-i) has terminal group silicon-bonded hydrogen atom and additional silicon-bonded hydrogen atom beyond terminal group silicon-bonded hydrogen atom per molecule and having a viscosity of from about 15 to about 100 centipoise at 25 degrees celsius, being present in an amount of from about 0.5 to about 1 weight percent; and
(B-ii) is substantially straight chain organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms that are only terminal group silicon-bonded hydrogen atoms per molecule and having a viscosity of from 1 to about 10 centipoise at 25 degrees celsius, being present in an amount of from about 0.5 to about 1 weight percent; and
(B-iii) substantially resinous organohydrogenpolysiloxane having a viscosity of from about 15 to about 60 centipoise at 25 degrees celsius, and being present in an amount of from about 1.5 to about 2.5 weight percent;said at least two organohydrogenpolysiloxanes (B) being used in an amount such that the mole ratio of total amount of silicon-bonded hydrogen atoms contained in at least two organohydrogenpolysiloxanes (B) to silicon-bonded alkenyl groups contained in at least two organopolysiloxanes (A) is of from about 1.3 to about 2.2; (C) filler in an amount of from about 15 to about 45 parts per hundred of polyorganosiloxane (A), wherein said filler (C) is finned silica with a surface area of from about 200 to about 350 m2/g, said fumed silica having been treated with silane, and where filler (C) is present in an amount of from about 20 to about 25 weight percent; (D) a platinum catalyst which is present in an amount of from about 5 ppm to about 30 ppm; and
,(E) 1-ethynyl- 1-cyclohexanol where said 1-ethynyl- 1-cyclohexanol is present in an amount of from about 0.02 to about 0.06 weight percent, with all weight percents being based upon the total weight of the curable high tear strength, low hardness silicone elastomer-forming composition, and where combined (A)-(E) comprises a curable high tear strength, low hardness silicone elastomer-forming composition.
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Specification