| 摘要 |
Blow molded multi-layered articles for automotive use, for example ducts, hoses, tubes, sealing devices and covers commonly include two layers of compatible material, both layers being formed of expensive, highly resistant materials. It has been found that the outer layer of a two-layered article or the middle (and possibly outer) layer of a three-layered article can be produced using a relatively inexpensive, non-resistant material without sacrificing flexiblity or other desirable physical properties of the finished product. For example, the inner and outer layers of a three-layered article can be formed of a thermoplastic rubber, which exhibits the elastomeric performance of vulcanized rubbers and the processing simplicity of thermoplastic polymers, and the middle layer can be formed of a polypropylene based thermoplastic elastomer.
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