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Abstract
Environmental protection and legislative pressure to eliminate the use of solvents in the adhesive industry have inspired the search for safer alternatives. In the area of contact adhesives, the waterborne route has proved to be of particular interest. Based on the synergistic effect of polychloroprene latex and styreneacrylate emulsion, a waterborne contact adhesive consisting of polychloroprene latex (PCL) and styreneacrylate emulsion (SAE) blend has been developed. In order to blend PCL with SAE easily and to accelerate the drying rate of the adhesive, boric acid was chosen for use in the PCL/SAE blend system. Effects of boric acid and SAE content on the properties of PCL/SAE blends, such as pH value, storage stability and set time, were investigated. At the same time, the effect of SAE content on the mechanical properties of PCL/SAE blend films was studied. The morphology of blend films was characterized by Atomic Force Microscopy. The adhesive performance of the waterborne contact adhesive was evaluated by peel and shear tests. The results showed that when the waterborne contact adhesive formulation contained 40 wt% styrene-acrylate emulsion (dry weight) and 1.25 wt% boric acid, it had a good shelf-stability, its set time was 5 min, and the blend film with this formulation was ductile and flexible with reasonably good tensile strength and very high elongation at break. And the blend films showed structure with a sea–island morphology. The waterborne contact adhesives derived from PCL/SAE blends were found to be comparable to the commercially available solvent-based contact adhesives. The synergistic effect of polychloroprene latex and styrene-acrylate copolymer emulsion was also discussed.