Ultraviolet cure adhesive formulations

Photosensitive adhesive formulations based on acrylates, epoxy acrylates, and polyurethane acrylics may be cured by exposure to ultraviolet or visible light. The key... 

Binders and Resins. The choice of binder is the most important ingredient choice in the formulation process because the binder affects the performance properties of a paint more than any other single ingredient (3). The physical properties of binders required for paints include the abiHty to dry or cure under various ambient conditions, good adhesion to various substrates, abrasion resistance, washabiHty, flexibiHty, water resistance, and ultraviolet light resistance. The balance of these required properties is mosdy dependent on whether the paint is being developed for interior or exterior appHcations. 

Dimethacrylates form highly cross-linked and, therefore, brittle polymers. To overcome brittleness, manufacturers often blend dimethacrylates with polyurethanes or other polymers such as low-molecular-weight vinyl-terminated butadiene-acrylonitrile copolymers and chlorosulfonated polyethylene. The modified dimethacrylate systems provide tough adhesives with excellent properties. These can be formulated as two-component adhesives, the catalyst component being added just prior to use or applied separately to the surface to be bonded. One-component systems also have been formulated which can be conveniently cured by ultraviolet radiation. 

The papers presented in the following chapters represent advances in pressure sensitive adhesives (ultraviolet light activated acrylate monomer - low Tg polyether formulations) photoinitiated cationic polymerization (light activated aryliodonium and arylsulfonium salts of lewis acids in epoxy resin formulations) polymer and formulation design criteria for radiation curable adhesives radiation curable composites (dynamic thermal analysis characterization of electron beam cured... 

Instead of directly curing an adhesive, ultraviolet light can replace chemical primers for anaerobic formulations under certain conditions. This technique involves applying the formulation to a substrate and irradiating the coated substrate for a prescribed length of time. Although the adhesive remains liquid, it has become susceptible to anaerobic polymerization and assembly leads to bond formation. 

While the overall rate of increase of adhesive consumption since 1950 has been high, the growth of certain types of products has been especially dramatic. Pressure sensitive and hot melt formulations have been very rapid gainers and anaerobic adhesives too have been strong performers in recent years. Specialty adhesives, including cyanoacrylates (the so-called instant glues) and ultraviolet radiation cured products have also been favorably received. 

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