| 摘要 |
PURPOSE:To contrive an improvement in durability of a mandrel by making a coating material hard to peel off from a core material even if water pressure is applied to an end face of the mandrel at the time of pulling out of the mandrel from a hose, by providing a primerlike inner layer joining the core material and an outer layer to each other between both of them. CONSTITUTION:A flexible mandrel 21 forming a width, the diameter and the surface is constituted of a core material 23 made of a metal wire and an inner layer 24 and outer skin layer 25 of a vulcanized product of EPDM with sulphur for coating the core material. An inner layer 23 is formed by making use of 100 pts. wt. of EPDM, 5-50 pts. wt. of liquid polybutadiene, 2-20 pts. wt. of process oil and 2-5 pts. wt. of sulphur. The outer layer 25 is made to be the vulcanized product of the EPDM with the solphur which is the same as that of a conventional example. The mandrel in an unvulcanized state is obtained by either covering the inner layer 24 and outer layer 25 through two- color extrusion at a time to the core material 23 or covering the inner layer 24 and outer layer 25 in order to the core material 23. Then the mandrel in the unvalcanized state is made into a product mandrel 21 by passing the same through a vulcanizing tank. |
