| Résumé : |
In the automobile industry, isocyanate coatings are becoming popular as they have been shown to be capable of formulating into a wide range of coatings suitable for even a wider range of high performance applications. The normal route to incorporate hydroxy functionality in acrylic resin for isocyanate curing is through the co-polymerisation with hydroxy ethyl acrylate (HEA) or with hydroxy ethyl methacrylate (HEMA). Curing of this acrylic resin with isocyanate has limited control on achieving the desired flexibility, crosslink density, drying time, etc. In view of overcoming these limitations, work has been carried out for designing suitable hydroxy functional base alkyd as an alternative to rigid hydroxy functional monomers (HEA or HEMA) so as to incorporate built in flexibility and drying improvement through the oil component.
In the present paper, the effect of oil length, type of polybasic acid, molecular weight of hydroxy functional base alkyd for acrylated alkyd for polyurethane coatings, is studied to optimize pot-life, drying and performance with reference to acrylic-isocyanate system. Isocyanate cured acrylated melanised alkyd based on medium oil or short oil promises several advantages over the isocyanate cured acrylics based on HEMA and EHA with respect to its excellent drying speed, gloss and chemical resistance, particularly ammonia resistance, besides comparable mechanical, corrosion and weathering resistance properties. |
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Hydroxy functional acrylated maleinised alkyd-an excellent base for polyurethane automotive refinishing paints in PAINTINDIA, Vol. XLV, N° 9 (09/1995)
