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US 6,146,579 AGranted
Process for producing thermoplastic resin hollow molded article
AssigneeSumitomo Chemical Company, Limited
InventorsMasahito Matsumoto, Satoru Funakoshi, Shigeyoshi Matsubara
Life of this patent
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Abstract
A hollow molded article having no sink marks on its surface and having an excellent appearance is produced by filling a mold cavity with a resin being in a molten state and then ejecting at least a part of the resin by sucking through a resin-ejection opening and introducing gas through a gas-introduction opening into the resin inside of which being in a negative pressure. According to this process, the use of a high-pressure gas is not required.
Claims10
A process for producing a hollow molded article of thermoplastic resin comprising:
- (a) providing a mold assembly comprising a mold including a first mold half and a second mold half wherein each mold half has a mold surface which can define a cavity with a mold surface of another mold half, at least one mold half has a resin-supply path which opens to the mold surface through a resin-supply opening, at least one mold half has a resin-ejection path which opens to its mold surface through a resin-ejection opening, at least one mold half has a gas path which opens to its mold surface through a gas-introduction opening and, at least one mold half has at least one suction opening that opens to its mold surface through a respective at least one suction path;
- (b) supplying a resin being in a molten state to between the mold surfaces through the resin-supply opening to fill the cavity with the resin;
- (c) cooling the resin to solidify at least a part of its surface and form a solidified surface layer;
- (d) holding on and contacting to the mold surface at least a part of the surface of the solidified layer by suction through said at least one mold half in which said at least one suction path is provided;
- (e) during the holding on and contacting, ejecting at least a part of a portion of the resin through the resin-ejection opening by sucking wherein the portion of the resin has not solidified yet;
- (f) introducing gas into the resin through the gas-introduction opening to form a hollow in the resin such that gas provided to form the hollow in the resin is not discharged with the resin being ejected through the resin-ejection path;
- and
- (g) cooling the resin in the cavity to solidify it and form the hollow molded article.
5 more elements
Dependencies are inferred from the claim text.