Bonding Dissimilar Materials with Adhesive Paste

Abstract

A rivetable adhesive for use in a joint between dissimilar materials, comprising a Nquid epoxy resin, an expoxidized polysulfide, a flexibilizer, a solid epoxy CTBN adduct based upon bisphenol A, a prienoxy resin, an impact modifier including methacrylate-butadiene-styrene, a curing agent; and a blowing agent. The adhesive finds particular suitability for use in riveting aluminum panels to steel structures, such as for forming automotive vehicle roof structures.

1 . An automotive vehicle assembly comprising:
 a support structure;   an aluminum panel adjacent the support structure;   at least one rivet joining the support structure to the aluminum panel;   a rivetable adhesive located in between the support structure and the aluminum panel, the adhesive comprising: a. a liquid epoxy resin; b. an epoxidized polysulfide; c. a flexibilizer; d. a solid epoxy CTBN adduct based upon bisphenol A; e. a phenoxy resin; f. an impact modifier including methacrylate-butadiene-styrene; g. a curing agent; and h. a blowing agent; wherein the adhesive exhibits a capillary viscosity of below 1000 PaS for a shear rate of 100 sec-1 or higher at a temperature of 70 or 90° C. such that the viscosity facilitates robotic application such that the adhesive is heated to be applied above room temperature, but below a temperature at which it would be activated for curing, expanding or both curing and expanding.   
     
     
         2 . The assembly of  claim 1 , wherein the liquid epoxy resin has an epoxide equivalent weight (g/eq) per ASTM D-1652-11e1 of about 182-192. 
     
     
         3 . The assembly of  claim 1 , wherein the impact modifier is a core shell impact modifier. 
     
     
         4 . The assembly of  claim 1 , including an aromatic substituted urea curing accelerator. 
     
     
         5 . The assembly of  claim 2 , wherein the blowing agent has a decomposition temperature of about 190 to 220° C. 
     
     
         6 . The assembly of  claim 3 , wherein the liquid epoxy resin is a resin reaction product of epichlorohydrin and bisphenol A having an epoxide equivalent weight per ASTM D-1652-11e1 of about 182 to about 192. 
     
     
         7 . The assembly of  claim 1 , wherein the liquid epoxy resin is present in an amount of about 15 to about 25 parts by weight of the adhesive. 
     
     
         8 . The assembly of  claim 7 , wherein the adhesive includes a liquid epoxy resin reaction product of an epichlorohydrin and a polypropylene glycol. 
     
     
         9 . The assembly of  claim 8 , wherein liquid epoxy resin reaction product of an epichlorohydrin and a polypropylene glycol is present in amount of about 3 to about 20 parts by weight of the adhesive. 
     
     
         10 . The assembly of  claim 1 , wherein the flexibilizer is present in an amount of about 1 to about 5 parts by weight of the adhesive. 
     
     
         11 . The assembly of  claim 1 , wherein the impact modifier is present in an amount of about 15 to about 25 parts by weight of the adhesive. 
     
     
         12 . The assembly of  claim 11 , wherein the solid epoxy CTBN adduct based upon bisphenol A is present in an amount of about 3 to about 15 parts by weight of the adhesive. 
     
     
         13 . The assembly of  claim 1 , wherein the phenoxy resin is present in an amount of about 15 to about 30 parts by weight of the adhesive. 
     
     
         14 . (canceled) 
     
     
         15 . The assembly of  claim 1 , wherein the adhesive includes about 0.5 to about 5 parts by weight of calcined kaolin. 
     
     
         16 - 20 . (canceled) 
     
     
         21 . The assembly of  claim 1 , wherein the adhesive is applied to one or more of the support structure and aluminum panel via a robotic arm and applicator. 
     
     
         22 . The assembly of  claim 1 , wherein the support structure comprises a steel material. 
     
     
         23 . The assembly of  claim 22 , wherein the adhesive is heated to a first temperature during application and heated to a second temperature during an automotive assembly process to cure. 
     
     
         24 . The assembly of  claim 23 , wherein the first temperature is lower than the second temperature. 
     
     
         25 . The assembly of  claim 23 , wherein the adhesive foams upon exposure to the second temperature. 
     
     
         26 . The assembly of  claim 1 , wherein the adhesive substantially prevents galvanic corrosion where the support and aluminum panel are connected.