Polyfunctional fluorosilicone crosslinkers, method for making, and use

Abstract

A fluorosilicone crosslinker and method for making is provided. Reaction is effected between a silanol terminated polyfluoroalkyl silicone fluid and a polyalkoxysilane in the presence of a Platinum Group Metal catalyst. The fluorosilicone crosslinker can be used in combination with a silanol terminated fluoroalkyl substituted polydiorganosiloxane to formulate a neutral, condensation curable, solvent resistant sealant.

What is claimed:  
     
         1 . A neutral, room temperature condensation curable, fluorosilicone sealant composition comprising: 
 (A) a silanol terminated fluoroalkyl substituted polydiorganosiloxane,    (B) an oligomeric fluorosilicone crosslinker,    (C) filler, and    (D) an effective amount of a condensation catalyst,    
     
     
         2 . The sealant composition in accordance with  claim 1 , where the polydiorganosiloxane is present at about 100 parts by weight of the sealant composition.  
     
     
         3 . The sealant composition in accordance with  claim 1 , where the polydiorganosiloxane comprises organofluorosiloxy units of the formula  
       R(R 1 )SiO—,  (1)  
       where R is a C (1-12)  organic radical, and R 1  is a C (3-8)  polyfluoroalkyl radical.  
     
     
         4 . The sealant composition in accordance with  claim 3 , where the polydiorganosiloxane comprises [trifluoropropyl(methyl)siloxy] units.  
     
     
         5 . The sealant composition in accordance with  claim 1 , wherein the crosslinker comprises the formula  
       (R 2 O) m (R) n SiO—[R(R 1 )SiO] x —Si(R) n (OR 2 ) m    
       where R is a C (1-12)  organo radical, R 1  is a C (3-8)  fluoroalkyl radical, R 2  is a C (1-12)  alkyl radical, “m” is an integer having a value of 2 or 3, “n” is an integer having a value of 0 or 1, and the sum of “m+n” is equal to 3, and “x” is an integer having a value in a range between about 3 and about 30 inclusive.  
     
     
         6 . The sealant composition in accordance with  claim 5 , where the crosslinker comprises a dimethoxymethylsilyl terminated methyltrifluoropropylsiloxane fluid.  
     
     
         7 . The sealant composition in accordance with  claim 5 , where the crosslinker is present in a range between about 1 part and about 20 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane.  
     
     
         8 . The sealant composition in accordance with  claim 1 , where the condensation catalyst comprises an organometallic compound.  
     
     
         9 . The sealant composition in accordance with  claim 8 , where the organometallic compound comprises dibutyltin diacetate, dimethyltin neodecanoate, dibutyltin dilaurate, stannous octoate, dimethyltin hydroxyoleate, or combinations thereof.  
     
     
         10 . The sealant composition in accordance with  claim 9 , where the organometallic compound comprises dibutyltin diacetate.  
     
     
         11 . The sealant composition in accordance with  claim 1 , where the condensation catalyst is present in a range between about 0.1 parts and about 5.0 parts by weight per 100 parts of the of sealant composition.  
     
     
         12 . The sealant composition in accordance with  claim 11 , where the condensation catalyst is present in a range between about 0.1 parts and about 1.0 parts by weight per 100 parts of the sealant composition.  
     
     
         13 . The sealant composition in accordance with  claim 1 , where the filler comprises fumed silica.  
     
     
         14 . The sealant in accordance with  claim 1 , where the filler is present in a range between about 0 parts and 30 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane.  
     
     
         15 . The sealant in accordance with  claim 14 , where the filler is present in a range between about 5 parts and about 15 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane.  
     
     
         16 . The sealant composition in accordance with  claim 1 , where the composition further comprises a heat stabilizer.  
     
     
         17 . The sealant composition in accordance with  claim 16 , where the heat stabilizer comprises iron oxide, ceric oxide, titanium dioxide, or combinations thereof.  
     
     
         18 . The sealant composition in accordance with  claim 17 , where the heat stabilizer comprises iron oxide.  
     
     
         19 . The sealant composition in accordance with  claim 1 , where the heat stabilizer is present in a range between about 0.1 parts and about 10 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane.  
     
     
         20 . A neutral, room temperature condensation curable, fluorosilicone sealant composition comprising by weight: 
 (A) a silanol terminated fluoroalkyl substituted polydiorganosiloxane which comprises [trifluoropropyl(methyl)siloxy] units present at about 100 parts by weight of the sealant composition,    (B) a diethoxymethylsilyl terminated methyltrifluoropropylsiloxane present in a range between about 1 part and about 20 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane,    (C) fumed silica filler in a range between about 5 parts and about 15 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane, and    (D) dibutyltin diacetate in a range between about 0.1 parts and about 1 parts by weight per 100 parts of the silanol terminated fluoroalkyl substituted polydiorganosiloxane.    
     
     
         21 . An oligomeric fluorosilicone crosslinker which comprises the formula,  
       (R 2 O) m (R) n SiO—[R(R 1 )SiO] x —Si(R) n (OR 2 ) m ,  
       where R is a C (1-12)  organo radical, R 1  is a C (3-8)  fluoroalkyl radical, R 2  is a C (1-12)  alkyl radical, “m” is an integer having a value of 2 or 3, “n” is an integer having a value of 0 or 1, and the sum of “m+n” is equal to 3, and “x” is an integer having a value in a range between about 3 and about 30 inclusive.  
     
     
         22 . A polyalkoxysilyl terminated oligomeric fluorosilicone crosslinker comprising in a range between about 3 and about 30 chemically combined [trifluoropropyl(methyl)silyloxy] units.  
     
     
         23 . A dialkoxyalkylsilyl terminated oligomeric fluorosilicone in accordance with  claim 22 .  
     
     
         24 . A polyethoxysilyl terminated oligomeric fluorosilicone in accordance with  claim 22 .  
     
     
         25 . A polymethoxysilyl terminated oligomeric fluorosilicone in accordance with  claim 22 .  
     
     
         26 . A method for making an oligomeric fluorosilicone crosslinker having terminal polyalkoxysilyl units which comprises effecting reaction between a silanol terminated fluoroalkyl substituted polydiorganosiloxane and a polyalkoxysilane in the presence of an effective amount of a Platinum Group Metal catalyst.  
     
     
         27 . The method in accordance with  claim 26 , where there is used in a range between about 2 moles and about 10 moles of polyalkoxysilane, per mole of silanol terminated fluoroalkyl substituted polydiorganosiloxane.  
     
     
         28 . The method in accordance with  claim 26 , where the reaction occurs at a temperature in a range between about −10° C. and about 150° C.  
     
     
         29 . The method in accordance with  claim 28 , where the reaction occurs at a temperature in a range between about 10° C. and about 40° C.  
     
     
         30 . The method in accordance with  claim 26 , where the Platinum Group Metal catalyst is present in a range between about 10 parts per million and about 10 3  parts per million per part of reaction mixture.  
     
     
         31 . The method in accordance with  claim 26 , where the silanol terminated fluoroalkyl substituted polydiorganosiloxane comprises the formula,  
       HO—[R(R 1 )SiO] x —OH  
       wherein R is a C (1-12)  organo radical, R 1  is a C (3-8)  fluoroalkyl radical, and “x” is an integer having a value in a range between about 3 and about 30 inclusive.  
     
     
         32 . The method in accordance with  claim 31 , where the silanol terminated fluoroalkyl substituted polydiorganosiloxane comprises chemically combined [trifluoropropyl(methyl)silyloxy] units.  
     
     
         33 . The method in accordance with  claim 26 , where the polyalkoxysilane comprises the formula,  
       HSi(R) n (OR 2 ) m ,  
       wherein R is a C (1-12)  organo radical, R 2  is a C (1-12)  alkyl radical, “m” is an integer having a value of 2 or 3, “n” is an integer having a value of 0 or 1, and the sum of “m+n” is equal to 3.  
     
     
         34 . The method in accordance with  claim 33 , where the polyalkoxysilane comprises triethoxysilane, trimethoxysilane, methyldiethoxysilane, methyldimethoxysilane, or combinations thereof.  
     
     
         35 . A method for making a triethoxysilyl terminated poly(methyltrifluoropropyl)siloxane comprising effecting reaction between a silanol terminated (methyltrifluoropropyl)siloxane and triethoxysilane in the presence of an effective amount of a Platinum Group Metal catalyst.  
     
     
         36 . A method for making a trimethoxysilyl terminated poly(methyltrifluoropropyl)siloxane comprising effecting reaction between a silanol terminated (methyltrifluoropropyl)siloxane and trimethoxysilane in the presence of an effective amount of a Platinum Group Metal catalyst.  
     
     
         37 . A method for making a methyldiethoxysilyl terminated poly(methyltrifluoropropyl)siloxane comprising effecting reaction between a silanol terminated (methyltrifluoropropyl)siloxane and methyldiethoxysilane in the presence of an effective amount of a Platinum Group Metal catalyst.  
     
     
         38 . A method for making a methyldimethoxysilyl terminated poly(methyltrifluoropropyl)siloxane comprising effecting reaction between a silanol terminated (methyltrifluoropropyl)siloxane and methyldimethoxysilane in the presence of an effective amount of a Platinum Group Metal catalyst.