Curable composition

Abstract

A curable composition used to produce a polyurethane foam comprises an isocyanate group-containing urethane pre-polymer (I) having an oxyalkylene ether skeleton and no siloxane skeleton, and an isocyanate group-containing urethane pre-polymer (II) having a siloxane skeleton and an oxyalkylene ether skeleton.

1 . A curable composition to be used to produce a polyurethane foam, the curable composition comprising:
 an isocyanate group-containing urethane pre-polymer (I) that has an oxyalkylene ether skeleton and no siloxane skeleton; and   an isocyanate group-containing urethane pre-polymer (II) that has a siloxane skeleton and an oxyalkylene ether skeleton, wherein   the siloxane skeleton is represented by the following formula (1);   
       
         
           
           
               
               
           
         
       
       and wherein
 R a  and R b  each independently represent a monovalent substituent group and r represents an integer equal to or larger than 1. 
 
     
     
         2 . The curable composition according to  claim 1 , wherein
 the urethane pre-polymer (II) has the oxyalkylene ether skeleton having the isocyanate group bonded thereto, and   the siloxane skeleton having the oxyalkylene ether skeletons bonded to both sides thereof.   
     
     
         3 . The curable composition according to  claim 1 , wherein
 the urethane pre-polymer (II) has the siloxane skeleton and the oxyalkylene ether skeleton bonded to each other through an alkylene skeleton, and/or a urethane bond or a urea bond.   
     
     
         4 . The curable composition according to  claim 1 , wherein
 the content of the siloxane skeleton in the urethane pre-polymer (II) is 0.001 to 5% by mass relative to 100% by mass of the total amount of an overall NCO group-containing compound contained in the curable composition.   
     
     
         5 . The curable composition according to  claim 1 , wherein
 R a  and R b  in the formula (1) are each independently a methyl group or an ethyl group.   
     
     
         6 . The curable composition according to  claim 1 , wherein
 the content of the siloxane skeleton in the curable composition is 0.001 to 5% by mass relative to 100% by mass of the curable composition, and wherein   R a  and R b  in the formula (1) are each a methyl group.   
     
     
         7 . The curable composition according to  claim 1 , wherein
 the number of the repeating units of siloxane constituting the siloxane skeleton in the urethane pre-polymer (II) is 1 to 100.   
     
     
         8 . The curable composition according to  claim 1 , wherein
 at least a portion of the urethane pre-polymer (I) and/or the urethane pre-polymer (II) is chain-elongated.   
     
     
         9 . The curable composition according to  claim 1 , further comprising a latent curing agent. 
     
     
         10 . The curable composition according to  claim 9 , wherein
 the latent curing agent is a fine particles-coated amine whose surface of a solid amine is coated with fine particles.   
     
     
         11 . The curable composition according to  claim 10 , wherein
 the fine particles-coated amine has the surface of the solid amine that has a melting point equal to or higher than 50° C. and a central particle diameter equal to or smaller than 20 μm, coated with the fine particles having a central particle diameter equal to or smaller than 2 μm, and has a heat amount equal to or smaller than 220 J/g at a second absorption peak measured using a differential scanning calorimeter.   
     
     
         12 . The curable composition according to  claim 1 , further comprising a plasticizer and a filler. 
     
     
         13 . The curable composition according to  claim 12 , wherein
 the plasticizer is an alkyl sulfonic acid phenyl-based ester (Mesamoll).   
     
     
         14 . A polyurethane foam produced using the curable composition according to  claim 1 . 
     
     
         15 . A method for producing the polyurethane foam according to  claim 14 , the method comprising the steps of:
 (i) mixing a gas into a curable composition comprising:
 an isocyanate group-containing urethane pre-polymer (I) that has an oxyalkylene ether skeleton and no siloxane skeleton; and 
 an isocyanate group-containing urethane pre-polymer (II) that has a siloxane skeleton and an oxyalkylene ether skeleton, wherein 
 the siloxane skeleton is represented by the following formula (1); 
   
       
         
           
           
               
               
           
         
       
       and wherein
   R a  and R b  each independently represent a monovalent substituent group and r represents an integer equal to or larger than 1;   
 (ii) discharging the curable composition having the gas mixed therein obtained at step (i), from a nozzle; and 
 (iii) curing the discharged curable composition, wherein 
 steps (i) and (ii) are conducted using a mechanical foaming apparatus. 
 
     
     
         16 . The method according to  claim 15 , wherein
 at step (i), a discharging exit is closed that is disposed in the mechanical foaming apparatus such that a pipe path through which the curable composition can flow and a cylinder communicate with each other,   a piston disposed inside the cylinder is moved to leave the discharging exit to thereby form a cylinder space having a predetermined volume in the cylinder,   the cylinder space is filled with a gas at a predetermined pressure,   the piston is moved toward the discharging exit to thereby compress the gas, and   the discharging exit is opened to thereby mix the compressed gas into the curable composition flowing through the pipe path.