One-pack addition curable silicone composition, method for storing same, and method for curing same

Abstract

Provided are a one-pack addition curable silicone composition compatible with both a good long-term storage property at room temperature under conditions whereby air is blocked to a constant level and the advance of an addition curing reaction at room temperature by being applied in a thin film of 1500 μm or less and exposed to air, which could not be obtained by conventional curable heat-dissipating grease, and a method for storing the same, and a method for curing this composition. A one-pack addition curable silicone composition having as essential ingredients: (A) organopolysiloxane having silicon-atom-bonded aliphatic unsaturated hydrocarbon groups and a specific kinematic viscosity; (B) one or more thermally conductive fillers selected from metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and allotropes of carbon; (C) organohydrogenpolysiloxane; and (D) a platinum group metal complex having an organic phosphorus compound represented by formula (1) R 1 x—P—(OR 1 ) 3-x   (1) (R 1 is a monovalent hydrocarbon group, x is 0-3) as a ligand.

1 . A one-pack addition curable silicone composition comprising as essential components:
 (A) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded aliphatic unsaturated hydrocarbon groups per molecule and having a kinematic viscosity of 60 to 100,000 mm 2 /s at 25° C.,   (B) 100 to 3,000 parts by weight of at least one heat conductive filler selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes,   (C) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms (i.e., SiH groups) per molecule in such an amount that the number of SiH groups divided by the total number of aliphatic unsaturated hydrocarbon groups in component (A) is 0.5 to 5, and   (D) an effective amount of a platinum group metal complex coordinated with an organophosphorus compound represented by the general formula (1):
   [Chemical Formula 1] 
   R 1   x —P—(OR 11 ) 3-x    (1)
 
   wherein R 1  which may be the same or different is an optionally substituted monovalent hydrocarbon group of 1 to 20 carbon atoms, and x is an integer of 0 to 3.   
     
     
         2 . The one-pack addition curable silicone composition of  claim 1 , further comprising (E) 1 to 200 parts by weight per 100 parts by weight of component (A) of a hydrolyzable organopolysiloxane compound having the general formula (2): 
       
         
           
           
               
               
           
         
         wherein R 1  which may be the same or different is an optionally substituted monovalent hydrocarbon group of 1 to 20 carbon atoms, and m is an integer of 5 to 100. 
       
     
     
         3 . The one-pack addition curable silicone composition of  claim 1  or  2 , further comprising (F) 0.01 to 10 parts by weight per 100 parts by weight of component (A) of a hydrolyzable organosilane compound having the general formula (3):
   [Chemical Formula 3] 
   R 2 —Si(OR 1 ) 3    (3)
 
 
       wherein R 1  which may be the same or different is an optionally substituted monovalent hydrocarbon group of 1 to 20 carbon atoms, and R 2  is an optionally substituted monovalent hydrocarbon group of 1 to 20 carbon atoms. 
     
     
         4 . The one-pack addition curable silicone composition of any  claim 1  or  2  wherein a storage stability of at least 3 months at 25° C. is developed when it is stored in a closed container made of a material having an oxygen permeability constant of up to 1×10 −12  cm 3  (STP) cm/cm 2 ·s·Pa, and addition cure reaction takes place at room temperature when it is applied as a thin film having a thickness of up to 1,500 μm and exposed to air. 
     
     
         5 . A method for storing the one-pack addition curable silicone composition of  claim 1  or  2 , comprising the step of storing the one-pack addition curable silicone composition in a closed container made of a material having an oxygen permeability constant of up to 1×10 −12  cm 3  (STP) cm/cm 2 ·s·Pa, whereby the silicone composition develops a storage stability of at least 3 months at 25° C. 
     
     
         6 . A method for curing the one-pack addition curable silicone composition of  claim 1  or  2 , comprising the steps of applying the one-pack addition curable silicone composition as a thin film having a thickness of up to 1,500 μm and exposing the film to air at room temperature for allowing addition cure reaction to take place at room temperature.