| 摘要 |
<p>School wall panel can be written on with chalk and has a transparent protective layer, of pref. polyester sheet over a soda pulp sheet, a decorative layer and an intermediate layer, both pref. of polyesteraminoplast sheet, and a base layer. All the layers are bonded together by heat and pressure, and the protective layer is roughened, pref. with carborundum grains. Pref. the decorative layer is green.</p> |
