Molding method for blow molded product
AssigneeIdemitsu Petrochemical Co., Ltd.
InventorTadahiro Kannari
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Abstract
The invention relates to a method for producing blow moldings, especially to a blow-molding method capable of efficiently producing blow moldings of crystalline thermoplastic resin having good surface gloss and good mold transferability of, for example, embossed patterns and, not warped, having a good appearance with no sinkmarks. The method comprises blowing and shaping a parison of a crystalline thermoplastic resin at a mold temperature falling between (the crystallization point of the resin −10° C.) and (the melting point of the resin), then keeping the thus-blown parison at a temperature falling between (the crystallization point of the resin −15° C.) and (the crystallization point thereof −45° C.) for a dwell time of from 30 to 300 seconds, and thereafter cooling it in an ordinary manner.
Claims3
A method for producing blow moldings of crystalline thermoplastic resin, which comprises setting a melt parison of a crystalline thermoplastic resin in a mold and then blowing the parison, the method comprising the steps of
- (1) blowing and shaping the parison at a mold temperature falling between the crystallization point of the resin minus 10° C. and the melting point of the resin;
- (2) cooling the blown parison at a temperature falling between the crystallization point of the resin minus 15° C. and the crystallization point thereof minus 45° C.,
- (3) keeping the blown parison for a dwell time falling between 30 and 300 seconds;
- and
- (4) cooling the blown parison in an ordinary manner.
Dependencies are inferred from the claim text.