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Patent EP0289230A2 successfully refreshed from Google Patents.
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EP0289230A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method of injection moulding and mouldings produced thereby

Assignee: Cinpres Ltd
•
Filing: 1988-04-22
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Granted: —
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Expires: 2008-04-22
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Abstract

Abstract A resin moulding is produced by introducing molten synthetic thermoplastic resin (19) into a mould cavity (13), sufficient to fill completely the mould cavity. Subsequently, during the cooling of the resin, pressurised gas is introduced into the resin within the mould cavity. The resin moulding cools and hardens in the mould cavity whilst the gas is maintained under pressure. The mould cavity is designed to manufacture mouldings with unevenly distributed thick walled sections (3) connected to at least one gate (4;44) for the introduction of the pressurised gas, which flows only within the resin forming the thick walled sections and immediately adjacent areas of the moulding thereby taking up the shrinkage in the resin.

Inventors

  • 👤 Kunio Yamazaki
  • 👤 Tetsuzi Mitsubishi Gas Chem.Co.House-106 Watanabe

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 07:31
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/1703; B29C45/1704; B29C45/46; B29C45/57; Y; Y10; Y10S; Y10S425/00; Y10S425/812

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 133 words
A method of producing resin mouldings comprising introducing molten synthetic thermoplastic resin (19) into a mould cavity (13), introducing pressurised gas into the resin, and allowing the resin moulding to cool and harden in the mould cavity whilst maintaining the gas under pressure, the mould cavity being designed to manufacture mouldings with unevenly distributed thick walled sections connected to at least one gate (4;44) for the introduction of the pressurised gas, characterised in that the mould cavity (13) is completely filled with the resin, and subsequently the pressurised gas is introduced into the resin within the mould cavity during the cooling of the resin, the gas flowing only within the resin forming the thick walled sections (3) and immediately adjacent areas of the moulding and thereby taking up the shrinkage in the resin.
Claim 2
Independent Claim 133 words
A method of producing resin mouldings comprising introducing molten synthetic thermoplastic resin (19) into a mould cavity (13), introducing pressurised gas into the resin, and allowing the resin moulding to cool and harden in the mould cavity whilst maintaining the gas under pressure, the mould cavity being designed to manufacture mouldings with unevenly distributed thick walled sections connected to at least one gate (4;44) for the introduction of the pressurised gas, characterised in that the mould cavity (13) is completely filled with the resin, and subsequently the pressurised gas is introduced into the resin within the mould cavity during the cooling of the resin, the gas flowing only within the resin forming the thick walled sections (3) and immediately adjacent areas of the moulding and thereby taking up the shrinkage in the resin.
Claim 3
Dependent Claim 42 words
A method as claimed in Claim 1, characterised by maintaining the pressure of the gas within the gas filled sections (3) during the cooling stage of the moulding cycle until the moulding can itself sustain the form dictated by the mould surface.
Claim 4
Dependent Claim 23 words
A method as claimed in Claim 2, characterised by subsequently venting the gas filled sections (3) to the atmosphere before opening the mould.
Claim 5
Dependent Claim 15 words
A moulding produced by a method as claimed in any one of the preceding claims.

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