Silicone rubber composition for extrusion molding

Abstract

Provided is a silicone rubber composition for extrusion molding, including: (A) 100 parts by mass of an organopolysiloxane represented by an average composition formula (1): R 1 n SiO (4-n)/2 (in the formula, R 1 represents identical or different, unsubstituted or substituted monovalent hydrocarbon groups, and n represents a positive number within a range from 1.95 to 2.04), (B) 0 to 50 parts by mass of a vinyl group-containing silicon compound, (C) 5 to 100 parts by mass of a reinforcing silica, and (D) an effective quantity of a curing agent, in which the vinyl group content relative to the combination of the components (A) through (D) is at least 1.0×10 −4 mol/g. The composition yields a cured product for which the elastic modulus increases across a temperature range from 30 to 110° C. and which is therefore capable of reducing the temperature dependency of acrylic optical fibers. The composition is suitable for extrusion molding.

1 . A silicone rubber composition for extrusion molding, comprising:
 (A) 100 parts by mass of an organopolysiloxane represented by an average composition formula (1) shown below:
   R 1   n SiO (4-n)/2   (1) 
   
       (wherein, R 1  represents identical or different, unsubstituted or substituted monovalent hydrocarbon groups, and n represents a positive number within a range from 1.95 to 2.04),
 (B) 0 to 50 parts by mass of a vinyl group-containing silicon compound, 
 (C) 5 to 100 parts by mass of a reinforcing silica, and 
 (D) an effective quantity of a curing agent, wherein 
 a vinyl group content relative to a combination of components (A) through (D) is at least 1.0×10 −4  mol/g. 
 
     
     
         2 . The composition according to  claim 1 , wherein a rate of elastic modulus variation R for a cured product of the composition, calculated using a formula shown below:
     R =( E   100   −E   30 )/ E   30 ×100   
       (wherein, E 30  represents an elastic modulus of the cured product at 30° C., and E 100  represents an elastic modulus of the cured product at 100° C.), is at least 5%. 
     
     
         3 . The composition according to  claim 1 , wherein the component (B) is at least one selected from the group consisting of vinyl group-containing silanes and vinyl group-containing silazanes. 
     
     
         4 . The composition according to  claim 1 , wherein the specific surface area of the component (C) measured using the BET method is 50 m 2 /g or greater. 
     
     
         5 . The composition according to  claim 1 , wherein the curing agent of the component (D) is at least one curing agent selected from the group consisting of:
 (i) an organic peroxide, and   (ii) a combination of an organohydrogenpolysiloxane and a platinum group metal-based catalyst.   
     
     
         6 . The composition according to  claim 1 , further comprising
 (E) 0.5 to 50 parts by mass of an organosilane or organopolysiloxane represented by a formula (3) shown below:
   R 4 O(SiR 3   2 O) m R 4   (3) 
   
       (wherein, R 3  represents identical or different, unsubstituted or substituted monovalent hydrocarbon groups, m represents a positive number within a range from 1 to 50, and each R 4  represents, independently, an alkyl group or a hydrogen atom), per 100 parts by mass of the component (A). 
     
     
         7 . A cured product obtained by curing the composition defined in  claim 1 , wherein a rate of elastic modulus variation R for the cured product, calculated using a formula shown below:
     R =( E   100   −E   30 )/ E   30 ×100   
       (wherein, E 30  represents an elastic modulus of the cured product at 30° C., and E 100  represents an elastic modulus of the cured product at 100° C.), is at least 5%. 
     
     
         8 . An extrusion molded product comprising the cured product defined in  claim 7 . 
     
     
         9 . A method for reducing the temperature dependency of an acrylic optical fiber sensor, comprising:
 disposing a cured product of the composition defined in  claim 1  between a target material that is to be measured using the acrylic optical fiber sensor, and the acrylic optical fiber sensor.