Method for preparing a functionalized polyorganosiloxane

Abstract

A method for preparing functionalized polyorganosiloxanes is disclosed. The method includes 1) combining starting materials including A) a boron—containing Lewis acid catalyst, and B) an organosilicon compound having an average, per molecule of at least 1 silicon bonded groups of the formula —OR2; wherein each R2 is an independently selected monovalent hydrocarbon group of 1 to 6 carbon atoms, thereby forming a catalyzed mixture; and thereafter 2) adding the catalyzed mixture into a starting material including C) an organohydrogensiloxane having at least 1 silicon bonded hydrogen atom per molecule, thereby preparing a product comprising the functionalized polyorganosiloxane and a by-product comprising HR2.

1 . A method for preparing a functionalized polyorganosiloxane comprising:
 1) combining starting materials comprising
 A) a boron—containing Lewis acid, and 
 B) an organosilicon compound having an average, per molecule of at least 1 silicon bonded group of the formula —OR 2 ; wherein each R 2  is an independently selected monovalent hydrocarbon group of 1 to 6 carbon atoms, thereby forming a catalyzed mixture; and thereafter 
   2) adding the catalyzed mixture into a starting material comprising
 C) an organohydrogensiloxane having at least 1 silicon bonded hydrogen atom per molecule, thereby preparing a product comprising the functionalized polyorganosiloxane and a by-product comprising HR 2 . 
   
     
     
         2 . The method of  claim 1 , further comprising: adding additional boron—containing Lewis acid, to C) the organohydrogensiloxane before adding the catalyzed mixture into the starting material comprising the organohydrogensiloxane in step 2). 
     
     
         3 . The method of  claim 1 , where step 2) is performed at a temperature of 5° C. to 40° C. 
     
     
         4 . The method of  claim 2 , where the additional boron containing Lewis acid is present in an amount of 5 ppm to 250 ppm based on weight of C) the organohydrogensiloxane. 
     
     
         5 . The method of  claim 1 , where the boron containing Lewis acid, and when present, and any additional boron containing Lewis acid, is provided in a total amount of 50 ppm to 6000 ppm, based on combined weights of B) the organosilicon compound and C) the organohydrogensiloxane. 
     
     
         6 . The method of  claim 1 , where in step 1), A) the boron containing Lewis acid is present in an amount of 5 ppm to 600 ppm based on weight of B) the organosilicon compound. 
     
     
         7 . The method of  claim 1 , where the method is performed at a temperature of 5° C. to 70° C. 
     
     
         8 . The method of  claim 1 , where the catalyzed mixture in step 1) is heated to 40° C. to 70° C. before step 2). 
     
     
         9 . The method of  claim 8 , where the catalyzed mixture is cooled to less than 40° C. in step 2). 
     
     
         10 . The method of  claim 1 , where the method is performed at a temperature of 10° C. to <25° C. 
     
     
         11 . The method  claim 1 , where A) the boron—containing Lewis acid is a trivalent boron compound with at least one perfluoroaryl group per molecule. 
     
     
         12 . The method of  claim 1 , where B) the organosilicon compound is selected from the group consisting of:
 an alkoxysilane of formula: R 1   (4-a) SiOR 2   a , where each R 1  is independently selected from the group consisting of a monovalent hydrocarbon group and a monovalent halogenated hydrocarbon group, each R 2  is a monovalent hydrocarbon group of 1 to 6 carbon atoms, and subscript a is 1 to 4;   
       an organosiloxane of formula: R 3   2 R X SiO—(R 3   2 SiO) b —SiR X R 3   2 , where each R 3  is independently selected from the group consisting of a monovalent hydrocarbon group and a monovalent halogenated hydrocarbon group, each R X  is the group of formula —OR 2 , and subscript b≥1; and
 a resin of unit formula: (R 1 SiO 3/2 ) m (R 1 R X SiO 2/2 ) n (R 1 R X   2 SiO 1/2 ) z , where subscript m is 0 to 20, subscript n is 1 to 20, subscript z is 0 to 20, each R 1  is independently selected from the group consisting of a monovalent hydrocarbon group and a monovalent halogenated hydrocarbon group, and each R X  is the group of formula —OR 2    
 
     
     
         13 . The method of  claim 1 , where C) the organohydrogensiloxane has unit formula:
   (HR 4   2 SiO 1/2 ) g (R 4   3 SiO 1/2 ) h (R 4   2 SiO 2/2 ) i (HR 4 SiO 2/2 ) j ,   
       where subscripts g, h, i, and j have values such that g≥0, h≥0, a quantity (g+h) has an average value of 2, i≥0, j≥0, and a quantity (g+j)>0, a quantity (i+j) ranges from 0 to 1000, and the quantity (g+j) has a value sufficient to provide the polyorganohydrogensiloxane with at least 1% silicon bonded hydrogen atoms; and each R 4  is an independently selected monovalent hydrocarbon group. 
     
     
         14 . The method of  claim 1 , further comprising: neutralizing residual boron—containing Lewis acid in the product. 
     
     
         15 . The method of  claim 1 , further comprising: during and/or after step 2), removing a by-product comprising HR 2 .