| 摘要 |
PURPOSE:To prevent the generation of scale in a coffee liquid extractor. CONSTITUTION:One end of an aluminum water pipe 12 is connected to a lower opening of a tube 14 made of a polycarbonate resin. When the extracting operation is carried out 10-odd times, a scale component separated from water heated by a heater 4 adheres to the internal surface of the tube 14. Under such a condition, when the internal surface of the tube 14 is immersed with the hot water by a new extracting operation, a part of a polymer chain of the surface of the resin is cut under a chemical reaction of the water so that a week interface layer is formed near an interface by a lowering in cohesive force or with a decomposition product. In this case, the water acts as plasticizer to lower the cohesive force which is adhesion force near the interface thereby causing peeling-off of a scale. |
