Silicone resin composition, encapsulating layer, reflector, and optical semiconductor device

Abstract

A silicone resin composition includes a cage octasilsesquioxane; a polysiloxane containing alkenyl groups at both ends containing an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane; a hydrosilylation catalyst; a hydroxyl group-containing polysiloxane, organohydrogenpolysiloxane, or a polysiloxane containing alkenyl groups at side chain.

What is claimed is: 
     
         1 . A silicone resin composition comprising:
 a cage octasilsesquioxane having a group represented by formula (1) below,   a straight chain polysiloxane containing alkenyl groups at both ends which contains, at both of its molecular ends, an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane,   a hydrosilylation catalyst, and   a polysiloxane containing alkenyl groups at side chain which contains two or more alkenyl groups at its side chain,   
       
         
           
           
               
               
           
         
         (where R 1  represents a monovalent hydrocarbon group; R 2  represents hydrogen or a monovalent hydrocarbon group; the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  in the cage octasilsesquioxane as a whole is, as an average value, in a range of 6.5:1.5 to 5.5:2.5). 
       
     
     
         2 . The silicone resin composition according to  claim 1 , wherein the cage octasilsesquioxane is represented by formula (2) below, 
       
         
           
           
               
               
           
         
         (where R 1  and R 2  are as defined above; and the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  is the same as above). 
       
     
     
         3 . The silicone resin composition according to  claim 1 , wherein the polysiloxane containing alkenyl groups at both ends is represented by formula (3) below: 
       
         
           
           
               
               
           
         
         (where R 3  represents a monovalent hydrocarbon group; R 4  represents an alkenyl group; and “a” represents an integer of 1 or more). 
       
     
     
         4 . The silicone resin composition according to  claim 1 , wherein the polysiloxane containing alkenyl groups at side chain is represented by formula (8) below, 
       
         
           
           
               
               
           
         
         (where A to D represent constituent units; A and D represent terminal units; B and C represent repeating units; R 5  represents a monovalent hydrocarbon group; R 6  represents an alkenyl group; “b” represents 0 or an integer of 1 or more; and “c” represents an integer of 2 or more). 
       
     
     
         5 . The silicone resin composition according to  claim 1 , wherein the polysiloxane containing alkenyl groups at side chain is represented by formula (9) below, 
       
         
           
           
               
               
           
         
         (where E to H represent constituent units, E to G represent repeating units; H represents a terminal unit; R 7  represents a monovalent hydrocarbon group; “e” represents an integer of 1 or more; “f” and “g” represent 0 or an integer of 1 or more; “h” represents an integer of 4 or more; and at least two R 7  groups are alkenyl groups per 1 molecule). 
       
     
     
         6 . The silicone resin composition according to  claim 1 , comprising a silicone resin precursor and the polysiloxane containing alkenyl groups at side chain,
 wherein the silicone resin precursor is obtained by allowing the cage octasilsesquioxane to react with the polysiloxane containing alkenyl groups at both ends in the presence of the hydrosilylation catalyst.   
     
     
         7 . An encapsulating layer used for encapsulating an optical semiconductor element,
 wherein the encapsulating layer is formed from a silicone resin composition, and the silicone resin composition comprises   a cage octasilsesquioxane having a group represented by formula (1) below,   a straight chain polysiloxane containing alkenyl groups at both ends which contains, at both of its molecular ends, an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane,   a hydrosilylation catalyst, and   a polysiloxane containing alkenyl groups at side chain which contains two or more alkenyl groups at its side chain,   
       
         
           
           
               
               
           
         
       
       (where R 1  represents a monovalent hydrocarbon group; R 2  represents hydrogen or a monovalent hydrocarbon group; and the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  in the cage octasilsesquioxane as a whole is, as an average value, in a range of 6.5:1.5 to 5.5:2.5). 
     
     
         8 . An optical semiconductor device comprising an optical semiconductor element and an encapsulating layer that encapsulates the optical semiconductor element,
 wherein the encapsulating layer is formed from a silicone resin composition, and the silicone resin composition comprises   a cage octasilsesquioxane having a group represented by formula (1) below,   a straight chain polysiloxane containing alkenyl groups at both ends which contains, at both of its molecular ends, an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane,   a hydrosilylation catalyst, and   a polysiloxane containing alkenyl groups at side chain which contains two or more alkenyl groups at its side chain,   
       
         
           
           
               
               
           
         
       
       (where R 1  represents a monovalent hydrocarbon group; R 2  represents hydrogen or a monovalent hydrocarbon group; and the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  in the cage octasilsesquioxane as a whole is, as an average value, in a range of 6.5:1.5 to 5.5:2.5). 
     
     
         9 . A reflector used for reflecting light emitted from an optical semiconductor element,
 wherein the reflector is formed from a light reflective composition containing a silicone resin composition and a light reflective component, and   the silicone resin composition comprises   a cage octasilsesquioxane having a group represented by formula (1) below,   a straight chain polysiloxane containing alkenyl groups at both ends which contains, at both of its molecular ends, an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane,   a hydrosilylation catalyst, and   a polysiloxane containing alkenyl groups at side chain which contains two or more alkenyl groups at its side chain,   
       
         
           
           
               
               
           
         
       
       (where R 1  represents a monovalent hydrocarbon group; R 2  represents hydrogen or a monovalent hydrocarbon group; and the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  in the cage octasilsesquioxane as a whole is, as an average value, in a range of 6.5:1.5 to 5.5:2.5). 
     
     
         10 . An optical semiconductor device comprising an optical semiconductor element and a reflector that reflects light emitted from the optical semiconductor element,
 wherein the reflector is formed from a light reflective composition containing a silicone resin composition and a light reflective component, and   the silicone resin composition comprises   a cage octasilsesquioxane having a group represented by formula (1) below,   a straight chain polysiloxane containing alkenyl groups at both ends which contains, at both of its molecular ends, an alkenyl group having the number of moles smaller than the number of moles of the hydrosilyl group of the cage octasilsesquioxane,   a hydrosilylation catalyst, and   a polysiloxane containing alkenyl groups at side chain which contains two or more alkenyl groups at its side chain,   
       
         
           
           
               
               
           
         
       
       (where R 1  represents a monovalent hydrocarbon group; R 2  represents hydrogen or a monovalent hydrocarbon group; and the molar ratio of monovalent hydrocarbon group:hydrogen in R 2  in the cage octasilsesquioxane as a whole is, as an average value, in a range of 6.5:1.5 to 5.5:2.5).