Reactivity of Acrylic-Melamine Resin High Solids Coatings and Physical Properties of Cured Films
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概要
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Reactivity of acrylic and melamine resins for high solids clear coatings during the cure process was measured continuously by using the reflective mode of FT-IR with a heating unit. Simultaneously the physical properties of cured films were measured. Experimental results indicate that transetherification between methoxyl groups of hexamethoxymethylmelamine and hydroxyl groups of acrylic resin predominantly takes place in the sulfonic acid catalyst system ; subsequently self-condensation reaction of melamine resins occurs in the conditions of bake temperature T?120°C and OCH<SUB>3</SUB>/OH&>1.<BR>In the case of system where OCH<SUB>3</SUB>/OH=2.8, the relationship between the physical properties (Knoop hardness number and cross-link density) and relative amount of reacted OCH<SUB>3</SUB> moles was observed in the two successive linear lines which have an refraction point at OCH<SUB>3</SUB>/OH=1. This result properly reflects the reactivity of melamine resin for the system OCH<SUB>3</SUB>/O>1. In the case of systems where OCH<SUB>3</SUB>/OH=1.0, all methoxyl groups completely reacted with hydroxyl groups at 140°C, and furthermore, physical properties of the cured films were not significantly altered by the bake time. In the condition of bake temperature T<120°C, inhibiting effect of blocking agent for acid catalyst was clearly observed in the transetherification reaction.
- Japan Society of Colour Materialの論文