Coating hybrid resins

The first demonstration of the industrial importance of heme peroxidases in grafting applications has been the development of hybrid resins from renewable sources to replace phenol-formaldehyde based resins. Phenolic resins are widely used in surface coatings, adhesives, laminates, molding, friction materials, abrasives, flame retardants, carbon membranes, glass fiber laminates, fiberboards, and protein-based wood adhesives, [5]. Table 7.1 and Fig. 7.2 summarize some of the... 

Polysiloxane-Silica Hybrid Resins as Abrasion-Resistant Coatings for Plastic Substrates... 

Uses Esteritication/transesteritication/polycondensation catalyst for prep, of polyesters, unsat. polyesters, alkyds suitable for food and pharmaceutical contact applies., such as coatings, epoxies, hybrid resins food pkg. adhesives, closures with sealing gaskets for food containers food-contact oaDer/oaDerboard... 

Acryflc coating powders have achieved some success in Japan utilizing resins having gflcydyl methylacrylate functionality cured with C q—0 2 dicarboxyflc acids (49). Hybrid polyester—acryflc coating powders have also been reported in which an acid functional polyester resin coreacts with a glycidyl-containing acryflc polymer (50). Hydroxyl functional acryflc resins cured with blocked isocyanates have also been available for many years in the United States and achieved some commercial success as appliance finishes. 

The distribution of powder coating sales by resin type for various geographical areas is given in Table 5. The polyester—epoxy hybrids account for 50% of the European market, yet have only market share <25% in the rest of the world. Similarly, the polyester urethanes, which account for only a small market share in Europe, find significant usage in the United States andjapan. AcryUcs hold a significant share only in the Japanese market. 

On the whole, the miniemulsion polymerization process proved to be effective for incorporating an alkyd resin into acrylic coated copolymers. The reaction produced stable, small particle size latexes that contain graft copolymer of the acrylic and alkyd components. Attempts at macroemulsion hybrid polymerization were unsuccessful. 

Binders for thermosetting powder coatings are often called a hardener. The hardeners are a mixture of a primary resin and a cross-linker. The major types of binders can be limited to polyester, epoxy, hybrid epoxypolyester, acrylic, and UV cure types. Polyester binders are used for good exterior durability, retention of gloss, and resistance to chalking. 

The growing commercial use of polymer colloids whose preparation involves step polymerisations, hybrid systems and/or new routes to dispersion of polymers has not yet spawned an equivalent level of activity in academic studies. The success of the Avecia ex Zeneca Resins) technology for preparation of polyurethane dispersions is a good example of the importance of such developments. There also is the attraction of using conventional solvent-borne coating vehicles e.g., alkyd resins) in aqueous media and hybrid systems... 

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