Abstract: A heat-resistant plastic tube is mainly made of a polyester-based elastomer and exhibits a change amount in angle of ±10° or less in a shape retainability performance test, a change rate in inner diameter of ±2% or less in a dimensional stability performance test, a change rate in yield strength of ±30% or less in a flexibility retainability performance test. The heat-resistant plastic tube can be subjected to a thermal bending at a temperature in a use environment or higher and exhibits excellent retention of the bent shape through the thermal bending after being left in the use environment.

Abstract: A tube having high fuel permeation resistance and high flexibility is provided. The tube includes a barrier layer including metaxylylene group-containing polyamide resin and flexible resin which exhibits compatibility with metaxylylene group-containing polyamide resin and is softer than metaxylylene group-containing polyamide resin, and a polyamide resin layer.

Abstract: A resin tube for automotive piping is made of a resin composition containing 6,6-nylon, an impact improver, 6/6,6-copolymer nylon and a plasticizer with a proportion in a mass ratio of the 6,6-nylon:the impact improver:the 6/6,6-copolymer nylon:the plasticizer to be in a range of 100:5-40:5-50:3-20. The resin tube for automotive piping is manufactured by preparing the above resin composition and molding the composition into a tube by extraction. The 6,6-nylon and the impact improver are mixed together in advance and/or the 6/6,6-copolymer nylon and the plasticizer are mixed together in advance.

Abstract: A pure-water pipe for fuel cell has an innermost layer made of fluoro resin or polyolefin resin wherein an entire body of the pipe is made of resin and the pipe has a value of (a total thickness of the pipe)/(a thickness of the innermost layer) in a range of 1.1 to 40. The pure-water pipe further has a layer in the outside of the innermost layer which contains one of polyamide, polyester elastomer and polyolefin elastomer or a layer in the outside of the innermost layer which contains non-plastic polyamide. The pure-water pipe further has a low hydrogen-permeable layer in the outside of the innermost layer. The low hydrogen-permeable layer contains ethylene-vinyl alcohol copolymer, polymethaxyleneadipamide, or polybutylene naphthalate.

Abstract: A resin tube has a multilayer resin structure. A first resin layer contains polybutylene naphthalate. Second and third resin layers are layers containing copolymer of polybutylene naphthalate and polytetramethylene glycol. The second resin layer is on an outer side of the first resin layer, and the third resin layer is on an inner side of the first resin layer. A fourth resin layer contains polybutyene terephthalate.

Abstract: A heat-resistant plastic tube is mainly made of a polyester-based elastomer and exhibits a change amount in angle of ±10° or less in a shape retainability performance test, a change rate in inner diameter of ±2% or less in a dimensional stability performance test, a change rate in yield strength of ±30% or less in a flexibility retainability performance test. The heat-resistant plastic tube can be subjected to a thermal bending at a temperature in a use environment or higher and exhibits excellent retention of the bent shape through the thermal bending after being left in the use environment.