| 摘要 |
PURPOSE:To raise the durability and stability of a heat-collecting plate for solar heaters, consisting of an inner layer and an outer layer, by forming the inner layer of a resin material having a higher fluidity at low temperatures than that of a resin material constituting the outer layer. CONSTITUTION:In a heat-collecting plate consisting of an inner layer B and an outer layer A for solar heaters, the inner layer B is formed from a resin material (e.g., low-density polyethylene) having a higher fluidity at low temperatures than that of a resin material (e.g., high-density polyethylene) constituting the outer layer A. In sort, since the inner layer has a lower viscosity than that of the outer layer at the same temperatures, the generation of pinholes, etc., in the inner layer can be lessened and also the amount of redidual stress due to compression can be reduced. Furthermore, stress or deformation resulting from the freezing of the heat-collecting plate can also be relaxed. Also, the use of high- density polyethylene in the outer layer enables the regidity at high temperatures (60-90 deg.C) to be retained. Thus, the heat stability of the heat-collecting plate when in use can be maintained and therefore, the heat-collecting plate having a high stability for a long period of time can be obtained. |
