US 5,130,075 AGranted

Method for press molding thermoplastic resin

AssigneeSumitomo Chemical Company, Limited

InventorsTakahisa Hara, Masahito Matsumoto, Nobuhiro Usui, Shigeyoshi Matsubara

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Abstract

A molded article of a thermoplastic resin having good appearance is molded with a pair of molds having a conduit for supplying a resin melt in one of the molds by closing the molds till a mold cavity clearance in a closing direction reaches a specific distance, opening the molds at a specific rate while starting supply of the resin melt into the mold cavity before the clearance reaches the thickness of the finally produced article, continuing opening of the molds while supplying the resin melt till the cavity clearance becomes larger than the thickness of the finally produced article, and closing the molds at a specific rate before or when resin supply is finished to mold and cool the supplied resin melt.

Claims3

Dependent claims

A method for press molding a thermoplastic resin using a pair of molds having a conduit for supplying a resin melt in one of the molds comprising steps of:

(a) closing the molds till a clearance of a cavity formed by said molds in a mold closing direction reaches a distance which is smaller than a thickness of a finally produced article,
(b) opening said molds at a rate of not larger than 40 mm/sec. and starting supply of said resin melt into said mold cavity through said conduit before said clearance reaches the thickness of the finally produced article,
(c) continuing opening of said molds while supplying said resin melt till said cavity clearance becomes larger than the thickness of the finally produced article, and
(d) closing said molds at a rate of 30 mm/sec. or lower before or when resin supply is finished to mold and cool said supplied resin melt.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 07/765,200Filed 25 Sep 1991
Priority: JP 2-26266928 Sep 1990
Granted: 14 Jul 1992
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B29C 43/34
Component parts, details or accessories; Auxiliary operations: feeding the material to the mould or the compression means
B29C 43/58
Component parts, details or accessories; Auxiliary operations: measuring, controlling or regulating
B29C 45/561
Using mould parts movable during or after injection, e.g. injection-compression moulding: injection-compression moulding
B29C 2045/562
Compression stroke, e.g. length thereof: velocity profiles of the compression stroke