| 摘要 |
PURPOSE:To secure excellent leakproof properties for a long period of time, by having a gasket composed of nylon which is well adjusted to 30-60% crystallinity as well as making up a film made of a vinylidene chloride-vinyl chloride copolymer over the whole surface of the said gasket. CONSTITUTION:Nylon's crystallinity varies somewhat with types of the nylon but it is desirable that nylon 11 and 12 are 30-60% and nylon 6, 66 and 610 are 40-60% in crystallinity, respectively. For your information, if these types of nylon are below figures of the lower limit of each crystallinity, it is hardly to say the leakproof is sufficient enough and in ontrast to this, in case figures exceed the upper limit, elasticity required for a gasket is lost. That is the reason. A vinylidene chloride-vinyl chloride copolymer covering the surface of a gasket 7 is especially desired to be composed of a copolymer of vinylidene chloride 85-90% and vinyl chloride 10-15%; this compound film 6 has no water absorbency at all and is very excellent even in abrasion resistance and alkaliproof, so that the film 6 of thin type can be easily formed up on the surface of the gasket. |
