Colored silicone rubber adhesive film and methods of use

Abstract

A colored silicone rubber adhesive film and methods of adhesion by means of the silicone rubber adhesive film are disclosed. The silicone rubber adhesive film comprises (A) an organopolysiloxane; (B) a wet method hydrophobized reinforcing silica; (C) an organohydridopolysiloxane; (D) an azo or anthroquinone pigment, and (E) a curing accelerator. The colored silicone rubber adhesive film is easily handled, possesses excellent workability, and most important, makes it possible to verify the degree and the point of completion of the curing due to the presence of the pigment.

That which is claimed:  
     
         1 . A method of adhering a metal substrate to a glass substrate comprising: 
 a) coating the surface of a metal substrate with a primer composition comprising a organosilicon compound selected from the group of silanes and organosiloxane oligimers having at least one alkoxy group to form a primer layer;    b) laminating said primer layer with a colored silicone-rubber adhesive film composition comprising: 
 (A) 100 parts by weight of an organopolysiloxane with an average unit formula R a SiO (4-a)/2 , where R is a substituted or unsubstituted hydrocarbon group with the provisio that at least two R groups are alkenyl groups, and a is a number between 1.9 and 2.1;  
 (B) 30 to 150 parts by weight of a wet method hydrophobized reinforcing silica having a specific surface area exceeding 200 m 2 /g, consisting essentially of SiO 4/2  units and organopolysiloxane units selected from the group consisting of R 3 SiO 1/2  units, R 2 SiO 2/2  units, RSiO 3/2  units, and mixtures thereof, where R is the same as defined above, and  
 wherein the mole ratio of the organopolysiloxane units to the SiO 4/2  units is within a range of 0.08 to 2.0;  
 (C) 0.1 to 10 parts by weight of an organohydridopolysiloxane comprising at least one silicon-bonded hydrogen atom;  
 (D) a pigment selected from the group of azo pigments and anthroquinone pigments present in an amount sufficient for coloring the silicone rubber adhesive film composition; and  
 (E) a curing accelerator in an amount sufficient to cure the silicone rubber adhesive film composition;  
 wherein said colored silicone rubber adhesive film composition has a tensile strength of 1.5 kg/cm 2  to 5.0 kg/cm 2  at 25° C.;  
   c) bringing the surface of said colored silicone rubber adhesive film into contact with a glass substrate;    d) curing said colored silicone rubber adhesive film composition at a temperature above 80° C. until the said colored silicone rubber adhesive film composition becomes colorless.    
     
     
         2 . The method of    claim 1    wherein the contact between said silicone rubber adhesive film and glass substrate is applied with a pressure between 0.1 to 20 kg/cm 2 .  
     
     
         3 . A method of adhering a metal substrate to a glass substrate comprising: 
 a) coating the surface of a metal substrate with a primer composition comprising, 
 i) an organosilicon compound having at least one alkoxy group selected from the group of silanes and organosiloxane oligimers, and  
 ii) a pigment selected from the group of azo pigments and anthroquinone pigments,  
 to form a colored primer layer on the surface of said metal substrate;  
   b) laminating said colored primer layer with a silicone rubber adhesive film composition comprising, 
 (A) 100 parts by weight of an organopolysiloxane with an average unit formula R a SiO (4-a)/2 , where R is a substituted or unsubstituted hydrocarbon group with the provisio that at least two R groups are alkenyl groups, and a is a number between 1.9 and 2.1;  
 (B) 30 to 150 parts by weight of a wet method hydrophobized reinforcing silica having a specific surface area exceeding 200 m 2 /g, consisting essentially of SiO 4/2  units and organopolysiloxane units selected from the group consisting of R 3 SiO 1/2  units, R 2 SiO 2/2  units, RSiO 3/2  units, and mixtures thereof, where R is the same as defined above,  
 wherein the mole ratio of the organopolysiloxane units to the SiO 4/2  units is within a range of 0.08 to 2.0;  
 (C) 0.1 to 10 parts by weight of an organohydridopolysiloxane comprising at least one silicon-bonded hydrogen atom;  
 (E) a curing accelerator in an amount sufficient to cure the silicone rubber adhesive film composition;  
 wherein said silicone rubber adhesive film composition has a tensile strength of 1.5 kg/cm 2  to 5.0 kg/cm 2  at 25° C.;  
   c) maintaining contact between the silicone rubber adhesive film and the colored primer layer for at least one hour to form a colored silicone rubber adhesive layer;    d) bringing the surface of said colored silicone rubber adhesive film into contact with a glass substrate, and    e) curing said colored silicone rubber adhesive film by heating at a temperature above 80° C. until the film becomes colorless.    
     
     
         4 . The method of    claim 3    wherein the organopolysiloxane has a degree of polymerization greater than 3000 and a viscosity greater than 1×10 6  mm 2 /s.  
     
     
         5 . The method of    claim 3    wherein the mole ratio of the organopolysiloxane units to the SiO 4/2  units is within a range of 0.08 to 1.5.  
     
     
         6 . The method of    claim 3    wherein the pigment is an azo pigment selected from the group consisting of monoazo pigments, diazo pigments, polyazo pigments, pyrazolone pigments, stilbene azo pigments, and thiazole.  
     
     
         7 . The method of    claim 3    wherein the pigment is xylyl-azoxylydene-2-napthole.  
     
     
         8 . The method of    claim 3    wherein the curing accelerator is selected from the group consisting of, organic peroxides, platinum catalysts, and combinations thereof.  
     
     
         9 . The method of    claim 3    wherein the adhesion accelerator comprises an organoalkoxysilane having organic functional groups selected from the group consisting of mercapto groups, amino groups, vinyl groups, allyl groups, hexenyl groups, methacryloxy groups, acryloxy groups, glycidoxy groups, and the partial hydrolyzation and condensation products of the said organoalkoxysilanes.  
     
     
         10 . The method according to    claim 1    wherein said metal substrate is selected from the group consisting of stainless steel, iron, aluminum, and zinc.  
     
     
         11 . The method according to    claim 3    wherein said metal substrate is selected from the group consisting of stainless steel, iron, aluminum, and zinc.