Surface glazing compsns. - of plasticized nitrocellulose plus acrylic esters to reduce coating applicn. temps. and pressure

摘要

Coating compsns. comprise nitrocellulose (I) blended with two other materials where one (II) is a polymer not reactive with (I) but added to modify the hardness of the coating, and the other (III) is a polymer which will react with (I), under crosslinking conditions promoted by an organic polyisocyanate and/or a tin (Sn) salt, to become an integral plasticiser. The compsn. is suspended in solvents contg. surfactants to minimise the viscosity of the compsn. for application to materials such as paper, cardboard, plastics, wood or metal. The compsns. are used for application of a glass providing a deep, hard, high gloss surface. Plasticisation of the nitrocellulose permits application at temps. =100 degrees C. avoiding drying and embrittlement of some substrate materials. Also allows roll nip pressures to be 1 kg/cm reducing rate of wear on calendar bearings and back-pressure rollers. Coatings may be applied at rates 15m/min. and calendered immediately after application, instead of after a 12-24h. delay necessary with conventional nitrocellulose-based glazing.