| 摘要 |
PURPOSE:To obtain a large-sized blow molded product without having surface roughening, by specifying a thickness of one layer of a straight-chainlike a polybutylene terephthalate (PBT) resin layer. CONSTITUTION:A branch PBT resin layer whose melt index measured under a condition where a temperature is 235 deg.C and load is 2,160g is 2.0 or less and a straight-chainlike PBT resin layer are laminated and a thickness of one layer of the striaght-chainlike PBT resin layer falls within a range of 2-50% of the total thickness of a molded product. In the case where a ratio of the total thickness of the straight-chainlike PBT to the total thickness is excessive, molten tension of a parison is weak, drawdown is generated and moldability is worsend remarkably. Then when the ratio is too little, prevention effect of surface roughening of the surface of a molded product becomes insufficient. The blow molded product is obtained by a method wherein the branch PBT resin and the straight-chainlike PBT resin are melted, coextruded by making them into a parison so that the straight-chainlike PBT resin layer becomes the outermost layer and/or the innermost layer and the same is molded with a blow molding method. |
