Lens-forming silicone resin composition and silicone lens

Abstract

Silicone resin compositions comprising (A) an organopolysiloxane containing at least two aliphatic unsaturated bonds and having a viscosity of 100-1,000,000 mPa·s at 25° C., (B) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms (SiH groups) in the form of HR 6 2 SiO-, and (C) a platinum group metal base catalyst cure into colorless transparent parts which are useful lenses.

1 . A lens-forming silicone resin composition comprising 
 (A) an organopolysiloxane containing at least two aliphatic unsaturated bonds in a molecule and having a viscosity of at least 100 mPa s at 250C,    (B) an organohydrogenpolysiloxane having in a molecule at least three hydrogensiloxy structures of the following formula:                          wherein R is a monovalent hydrocarbon group, and    (C) a platinum group metal base catalyst, the composition becoming colorless and transparent when cured.    
   
   
       2 . The composition of  claim 1  wherein component (A) is an organopolysiloxane having the general formula (1):  
     
       
         
         
             
             
         
       
     
     wherein R 1  is each independently a substituted or unsubstituted monovalent hydrocarbon group, R 2  is each independently an aliphatic unsaturation-free, substituted or unsubstituted monovalent hydrocarbon group, k and m each are 0 or a positive integer, k+m is such a number that the organopolysiloxane has a viscosity of 100 to 1,000,000 mPa·s at 25° C.  
   
   
       3 . The composition of  claim 1  wherein component (A) is an organopolysiloxane of resin structure having the average compositional formula:  
       (R 3 SiO 1.5 ) x (R r   2 SiO) y (R 5   3 SiO 0.5 ) z    
     wherein R 3 , R 4  and R 5  are each independently a substituted or unsubstituted monovalent hydrocarbon group, 2 to 45 mol % of the entire monovalent hydrocarbon groups being vinyl, x, y and z representative of the molar ratio of corresponding siloxane units are such numbers that x/(x+y+z) is 0.3 to 0.95, y/(x+y+z) is 0.05 to 0.50, and z/(x+y+z) is 0 to 0.05.  
   
   
       4 . The composition of  claim 1  wherein component (B) is an organohydrogenpolysiloxane having the average compositional formula:  
       H a (R 6 ) b SiO (4-a-b)/2  (1)  
     wherein R 6  is each independently an aliphatic unsaturation-free, substituted or unsubstituted monovalent hydrocarbon group, a and b are positive numbers satisfying 0.001≦a <2, 0.7≦b≦2, and 0.8≦a+b ≦3, said organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms (SiH groups) in the form of HR 6   2 SiO- in a molecule.  
   
   
       5 . A silicone lens obtained by molding and curing the composition of  claim 1 .  
   
   
       6 . The silicone lens of  claim 5  for use in an LED device.