Method to activate silicone rubber surfaces

Abstract

A method for activating silicone rubber surfaces comprising steps of: i) swelling at least the surface of the silicone rubber matrix with a silicone rubber swelling solvent; ii) treating the silicone rubber matrix during or after the swelling with a solution comprising at least a reactive silane, the reactive silane comprising: a) at least one Si—C bond and; b) at least one hydrolytically labile bond linked to at least one of the Si atoms present in the reactive silane and; c) at least one functional group F1 connected via a Si—C bond to the same or an other Si atom present in the reactive silane, the functional group comprising electrophilic and/or nucleophilic moieties, and/or at least one functional group F2 connected via a Si—C bond to the same or an other Si atom present in the reactive silane comprising moieties which become electrophilic or nucleophilic moieties by a mechanism selected from the group consisting of ring opening of a cyclic structure, hydrolysis, displacement or by a migration reaction; iii) drying and/or heat treating of the treated silicone rubber matrix.

1 . A method for activating silicone rubber surfaces comprising steps of:
 i) swelling at least a surface of a silicone rubber matrix with a silicone rubber swelling solvent;   ii) treating the silicone rubber matrix during or after the swelling with a solution comprising at least a reactive silane, wherein the reactive silane comprises at least one hydrolytically labile bond linked to at least one of the Si atoms present in the reactive silane, the reactive silane comprising a reactive silane according to Formula (I) or (II), thereby forming a treated silicone rubber matrix; and   iii) drying and/or heat treating the treated silicone rubber matrix,   wherein   Formula (I) is:   
       
         
           
           
               
               
           
         
         wherein R1, R2, and R3 are independently selected from the group consisting of branched and linear, substituted and unsubstituted alkyl, alkenyl and alkoxy groups, halogens and hydrogen; and wherein R4 is selected from the group consisting of primary, secondary or tertiary amines, thiols, hydroxyls, carboxyl groups, mono- or poly-unsaturated ethylenic functionality, an allylic, acrylic, vinylic, epoxide functionalities and combinations thereof, and 
         Formula (II) is: 
       
       
         
           
           
               
               
           
         
         wherein R5 is selected from hydrogen, and substituted and unsubstituted, branched and straight chain, alkyl, alkenyl, alkynyl, aryl, alkylene ether, alkenyl ether, alkynyl ether or aryl ether groups, and wherein, in R5, oxygen atoms are not bonded together so as to form peroxy functionality; 
         R6 is selected from substituted and unsubstituted, branched and straight chain alkyl groups, alkylene ether groups, amines, ethers, esters and other connecting functional moieties; 
         R7 is selected from substituted and unsubstituted, branched and straight chain alkylene groups, wherein each R7 group in Formula (II) may be the same or different; 
         R8 is selected from substituted and unsubstituted, branched and straight chain alkylene, alkylene ether and alkenyl ether groups, and an ether linkage; 
         X is a hydrolyzable group capable of bonding to a siliceous substrate and of being displaced by a silicon-oxygen bond or a non-hydrolyzable organic functional group, wherein at least one of the X groups on each Si atom is hydrolyzable; 
         n is 0 or an integer which is no greater than 3; 
         y is 0 or an integer which is no greater than 3; and 
         wherein 2<n+y<3; and n and y are never both zero. 
       
     
     
         2 . The method according to  claim 1  wherein the hydrolytically labile bond is present in the form of a —Si—O—Si— bond, or as a hydrolysable group linked to a Si atom selected from the group consisting of halogens, methoxy groups, ethoxy groups, other alkoxy groups, amines, thiols and combinations thereof. 
     
     
         3 . The method according to  claim 1 , wherein the reactive silane comprises a functional group selected from the group consisting of primary, secondary or tertiary amines, thiols, hydroxyls, carboxyl groups and combinations thereof. 
     
     
         4 . The method according to  claim 1 , wherein the reactive silane comprises a functional group selected from the group consisting of mono- or poly-unsaturated ethylenic functionalities, allyl, acrylic, vinylic and epoxide functionalities and combinations thereof. 
     
     
         5 . The method according to  claim 1 , wherein the reactive silane comprises an amine functional group. 
     
     
         6 . The method according to  claim 1 , wherein the amount of reactive silane in the solution is from 0.5 to 20 wt %. 
     
     
         7 . The method according to  claim 1 , wherein the reactive silane is dispersed or dissolved in the silicone rubber swelling solvent. 
     
     
         8 . The method according to  claim 1 , wherein the reactive silane comprises a reactive silane according to Formula (I). 
     
     
         9 . The method according to  claim 1 , wherein the reactive silane comprises a reactive silane according to Formula (II). 
     
     
         10 . The method according to  claim 1 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.05. 
     
     
         11 . The method according to  claim 1 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.10. 
     
     
         12 . The method according to  claim 1 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.20. 
     
     
         13 . The method according to  claim 1 , wherein the silicone rubber swelling solvent is selected from the group consisting of pentane, hexane, cyclohexane, heptane, ethyl acetate and diethyl ether, and mixtures thereof. 
     
     
         14 . The method of  claim 1 , further comprising the step of applying a hydrophilic coating to the surface of the silicone rubber matrix. 
     
     
         15 . A silicone rubber surface that has been activated by the method according to  claim 1 . 
     
     
         16 . The method according to  claim 9 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.10. 
     
     
         17 . The method according to  claim 9 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.20. 
     
     
         18 . The method according to  claim 9 , wherein the silicone rubber swelling solvent is selected from the group consisting of pentane, hexane, cyclohexane, heptane, ethyl acetate and diethyl ether, and mixtures thereof. 
     
     
         19 . The method according to  claim 1 , wherein the compounds of Formula (I) are selected from 4-aminobutyltriethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethyoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-aminopropyldimethylfluorosilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, mercaptomethylmethyldiethoxysilane, (3-trimethoxysilylpropyl)diethylenetriamine, (3-glycidoxypropyl)triethoxysilane, 3-glycidoxypropyl)trimethoxysilane, (methacryloxymethyl)methyldimethoxysilane, (methacryloxymethyl)trimethoxysilane, methacryloxypropylmethyldichlorosilane, and methyacryloxypropyltrimethoxysilane. 
     
     
         20 . The method according to  claim 19 , wherein the silicone rubber swelling solvent is capable of causing a swelling ratio of the silicone rubber matrix of higher than 1.20.