| 摘要 |
Provided are scratch-resistant blow moldings of crystalline resin having good surface gloss and high surface hardness, and an efficient method for producing them. A crystalline resin melt parison is blown in a blow mold into a blow-molded article. In the method, the temperature of the inner wall of the mold is so controlled that it falls between a temperature lower by 20 DEG C than the crystallization temperature of the crystalline resin and a temperature below the temperature lower by 5 DEG C than the melting point of the crystalline resin, while the parison is prepared in the mold; then, after the mold has been clamped to pinch the parison therein, a pressure fluid is introduced into the thus-pinched parison; then the mold with the parison therein is so heated that the temperature of its inner wall falls between a temperature lower by 10 DEG C than the melting point of the crystalline resin and a temperature below the melting point of the crystalline resin; the parison is kept in the mold at the controlled temperature for a satisfactory period of time enough for the thus blow-molded article of the parison to have a surface hardness of not lower than the level of HB in terms of the pencil hardness measured in a pencil scratch test; and finally the mold is cooled and the blow-molded article is released from the mold. The blow moldings of crystalline resin produced in the method have a surface gloss of at least 80 %, and their surface scratch resistance in terms of the pencil hardness measured in a pencil scratch test is at least on the level of HB. |
