1-16 BASIC KNOWLEDGE ABOUT PAINTS AND PAINTING (6) TOP COAT PAINTS The top coat is applied last to give the color, luster, smoothness and other cosmetic qualities to the vehicle. At the same time, the top coat must protect these qualities over a long period of time from external factors (sunlight, rain, bird droppings, etc.). Top coats may be divided into several groups as shown below.
,-- NC lacquer --1 Air-drying type '-- CAB acrylic lacquer r----1 Acrylic urethane lacquer ITop coatsl Dual-component r-- ,-- Quick-drying type acrylic urethane '-- Acrylic urethane r--- ~ Standard acrylic urethane - Thermosetting amino alkyd ~ Baked type r-- - Thermosetting acrylic CD Air-drying type (lacquers) This type of top coats is commonly known as lacquers, and is divided into NC lacquers, NC acrylic lacquers and CAB acrylic lacquers by the kind of resins used. Air-drying type top coats have the following properties: · Quick-drying · Require polishing when dry · Far less resistant against weathering or chemicals than the top coat in the car production line.
® Dual-component type (urethane type) This type of top coats is called the urethane type because the drying process includes an urethane reaction, which forms a net-like structure. It is also called the dual-component type two products, namely the main agent and the hardener, that are kept separately are mixed together before application. The urethane type dual-component top coats are further divided into three groups by the type of resins used and the length of the drying time. 1. Standard acrylic urethane 2. Acrylic urethane lacquer 3. Quick-drying acrylic urethane - 18- NC acrylic lacquer