Portions of the surface of molded plastic articles are frequently coated with a paint that primarily serves a decorative purpose; for example, metallic coatings on mobile phones or casings for consumer electrical products.
In automotive applications, paints of various colors may be coated on the reverse side of clear plastic parts to match other interior colors or to give a metallic appearance. But the paint may also be functional, such as an aid to polish out machine and mold marks, a barrier coating to reduce or prevent plasticizer migration from molded articles, or an aid to reduce damage from marring, abrasion, and weathering.
Vinyl Plastics
Plasticized polyvinyl chloride products have found wide acceptance by consumers in diversified applications such as upholstery for automobiles and furniture; automotive door panels, dashboard pads, and headliners; drapery sheeting; purses and luggage; and garments.
Vinyl plastics are coated for various reasons, including:
(1) to change the color of the plastic
(2) to control surface gloss
(3) to impart a dry feel
(4) to retard or prevent plasticizer migration.
Vinyl lacquers modified with CAB and an acrylic resin are suggested starting points for developing coatings for hard-to-coat vinyl plastics.
Thermoplastic Elastomers
Coatings with exceptionally good flexibility can be prepared by blending CAB with urethane elastomers for application to thermoplastic elastomers.
The coated elastomeric plastics are used in exterior auto parts, gears, seals, gaskets, valves, tubing, footwear, toys, and sports equipment.
Thermosetting Plastics
Aliphatic polyurethane coatings have demonstrated resistance to chemical attack and weathering in application on thermosetting plastic surfaces.
By the addition of Eastman CAB-381 to these coatings, lacquer-type finishes can be formulated to provide uperior resistance to chemical and weathering attack and improved "feel" or "hand."
The use of Eastman CAB reduces the drying time of the coating and provides hydroxyl groups for subsequent crosslinking with isocyanate prepolymers. Pigment grinds are easily combined with butyrate lacquers either during or after dissolving the butyrate.
CAB based systems can be formulated to give good adhesion on ABS (acrylonistrile-butadiene-styrene copolymer), acrylic, cellulosic and polystyrene substrates. For adhesion on polyolefin substrates, use with an adhesives promoter will have to be evaluated.