| 摘要 |
<p>PURPOSE:To improve the durability of a coated film to reduce dropout and a scratch by allowing a back layer to contain carbon black, graphite, and a hardener. CONSTITUTION:Though carbon black contained in the back layer is not limited especially, carbon black having an average particle size of 10-150mmu is desirable, and especially, carbon black having an average size of 50-100mmu is most desirable. Graphite having <=3mu average particle size is desirable, and graphite having <=1mu average particle size is more desirable, and graphite having <=0.5mu average particle size is most desirable. As the hardener used in the back layer, a resin which has <=200,000mol.wt. in the state of an applied liquid and is not softened or fused till thermal decomposition is desirable. Concretely, a phenol resin, an epoxy resin, a polyurethane hardening resin, an urea resin, melamine resin, or the like is used.</p> |
