Millable-type silicone rubber composition and silicone rubber cured product
A millable-type silicone rubber composition, including: (A) 100 parts by mass of an organopolysiloxane represented by following average composition formula (1), the organopolysiloxane having polymerization degree of 100 or more, wherein a content of a low molecular siloxane contained as an impurity and having a polymerization degree of 10 or less is less than 1,000 ppm; (B) 5 to 100 parts by mass of a treated silica treated with a vinyl group-containing alkoxysilane and/or a vinyl group-containing organosilazane, the treated silica having a hydrophobicity degree of 40 or more; and (C) an effective amount of a curing agent. This provides a millable-type silicone rubber composition that yields a silicone rubber cured product with: a total of low molecular siloxane components having polymerization degree of 10 or less of less than 1,000 ppm; a small change in plasticity degree of the silicone rubber compound; and a small compression set. R1 a SiO(4- a )/2 (1)
1 . A millable-type silicone rubber composition, comprising:
(A) 100 parts by mass of an organopolysiloxane represented by the following average composition formula (1), the organopolysiloxane having at least two alkenyl groups in one molecule and having a polymerization degree of 100 or more, wherein a content of a low molecular siloxane contained as an impurity and having a polymerization degree of 10 or less is less than 1,000 ppm;
R 1 a SiO (4-a)/2 (1),
wherein R 1 is identical to or different from each other, and represents an unsubstituted or substituted monovalent hydrocarbon group, and “a” represents a positive number of 1.95 to 2.05,
(B) 5 to 100 parts by mass of a treated silica treated with any one or both of a vinyl group-containing alkoxysilane and a vinyl group-containing organosilazane, the treated silica having a hydrophobicity degree of 40% or more; and
(C) an effective amount of a curing agent.
2 . The millable-type silicone rubber composition according to claim 1 , wherein the component (B) is the treated silica treated with any one or both of the vinyl group-containing alkoxysilane and the vinyl group-containing organosilazane, a content of the vinyl group being 0.0001 mol or more relative to 100 parts by mass of the silica.
3 . The millable-type silicone rubber composition according to claim 1 , wherein the component (C) is an addition-reaction curing agent being a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst.
4 . The millable-type silicone rubber composition according to claim 2 , wherein the component (C) is an addition-reaction curing agent being a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst.
5 . The millable-type silicone rubber composition according to claim 1 , wherein the component (C) is an organic peroxide curing agent.
6 . The millable-type silicone rubber composition according to claim 2 , wherein the component (C) is an organic peroxide curing agent.
7 . The millable-type silicone rubber composition according to claim 3 , wherein the component (C) is an organic peroxide curing agent.
8 . The millable-type silicone rubber composition according to claim 4 , wherein the component (C) is an organic peroxide curing agent.
9 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 1 .
10 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 2 .
11 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 3 .
12 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 4 .
13 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 5 .
14 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 6 .
15 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 7 .
16 . A silicone rubber cured product, comprising a cured product of the millable-type silicone rubber composition according to claim 8 .