| 摘要 |
PURPOSE:To provide a hollow extrusion molded object having a multilayered structure of two or more layers, excellent in appearance shape and especially reduced in the warpage or deformation of the end part thereof. CONSTITUTION:All of respective resin layers laminated by a co-extrusion molding method are composed of a crystalline resin of which the main chain is mainly constituted of a repeated unit represented by the same chemical formula and the resin layer forming an outer layer is formed by using a resin having an m.p. lower than that of the resin of the resin layer forming the inner layer arranged just under the outer layer by 2-18 deg.C. The characteristic of a crystalline resin increased in shrinkage factor by crystallization is utilized contrarily to suppress a degree of deformation. |
