| 摘要 |
PURPOSE:To realize highly reliable selective absorption on a high-density polyethylene base material, the bonding onto which is normally difficult, by a structure wherein metallic powder in a first coating layer suppresses the infrared radiation from high-density polyethylene used as the base material and yet a second coating layer having a selective absorptivity of the sunlight is formed onto the first coating layer. CONSTITUTION:The first coating layer II mainly consists of thermoplastic acrylic resin, alkyd resin, chlorinated polyethylene, or epoxy resin 2 and metallic powder 3. The second coating layer III has excellent absorptivity in the visible light range of the sun and sufficient transparency in its infrared range. Consequently, the sunlight A is absorbed by the second coating layer III and at the same time converted to heat in order to heat-transfer to a heat transfer medium side (b). On the other hand, the radiation loss from the surface is small by being governed by the metallic powder 3 in the first coating layer II, because the second layer III is sufficiently transparent with respect to infrared rays, resulting in realizing sufficient selective absorption. In addition, because of the base material being of chlorinated polyethylene, no difficulty is aroused in bonding work. |
