29 августа, 2015 
Malyar Over the last four decades there have been a number of attempts to wed the unique benefits of polyurethane adhesives with the benefits of other adhesive systems. These attempts have led to the reporting of a variety of urethane hybrids. Early work focused on simple blends; for example, in 1964 Union Carbide blended organic isocyanates with ethylene-vinyl acetate copolymers [66]. These blends were used as an adhesive interlayer in glass laminations, particularly safety glass laminates. Similarly, polylurethane-epoxy blends for safety glass laminates were reported in 1970 [67].
More recent efforts have focused on developments that create true hybrids. For example, blocked isocyanate prepolymers have been mixed with epoxy resins and cured with amines [68-70]. These blocked prepolymers will react initially with the amines to form amine-terminated prepolymers that cross-link the epoxy resin. Several blocked isocyanates are commercially available. The DESMOCAP (Bayer) 11A and 12A products are isocyanates (believed to be blocked with nonylphenol) used as flexibilizing agents for epoxy resins. ANCAREZ (trademark, Pacific Anchor, Inc.) 2150 is a blocked isocyanate epoxy blend used as an adhesion promoter for vinyl plastisols. A one-package, heat — cured hybrid adhesive was reported consisting of isophorone diisocyanate, epoxy resin, and a dispersed solid curative based on the salt of ethylenediamine and bisphenol A [71]. Urethane amines are offered commercially that can be used with epoxy resins to develop hybrid adhesive systems [72].
Urethane acrylic hybrids have been reported based on several approaches. Pacific Anchor has developed a urethane acrylate that is commercially available (ANCAREZ 300A). Acrylic polyols have been synthesized in the presence of polyether polyols by Saunders for use in two-component structural adhesives with improved tensile and impact strength [73,74]. Pressure-sensitive acrylic prepolymers with hydroxyl groups have been formulated with isocyanate prepolymers to give adhesives with improved peel strength [75,76]. Aqueous-based vinyl-to-fiberboard adhesives were reported by Chao using water-dispersible MDI with a functionalized acrylic latex and an aqueous dispersion polyurethane to given improved shear and hot peel strength [77]. Acrylonitrile dispersion graft polyether polyols have also been used in two-component SMC adhesives [78].
Urethanes have also been used to toughen vinyl-terminated acrylic adhesives for improved impact resistance. Thus rubber-toughened urethane acrylates [79,80], water — dispersible urethane acrylates [81], and high-temperature-performance urethane-acrylate structural adhesives have been reported [82]. Polyurethanes terminated with acrylic functionality are also used for anaerobic or radiation-cured adhesives with improved toughness [83].
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