Method for producing a thin film

• US 5,552,094 A
• Filed: 08/26/1994
• Issued: 09/03/1996
• Est. Priority Date: 08/27/1993
• Status: Expired due to Term

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Kubota, Atsushi
• Primary Examiner(s): HEITBRINK, JILL LYNNE
• Application Number:
  US08/296,786
• Time in Patent Office: 739 Days
• Field of Search: 264/40.1, 264/40.5, 264/328.7, 264/2.2, 425/145, 425/149, 425/150
• US Class Current: 264/40.5
• CPC Class Codes: B29C 2045/565 Closing of the mould during injection
• CPC Class Codes: B29C 2045/567 Expelling resin through the gate
• CPC Class Codes: B29C 2945/76006 Pressure
• CPC Class Codes: B29C 2945/76257 cavity
• CPC Class Codes: B29C 45/561 Injection-compression moulding

Abstract

A method of producing thin-film products consisting of injecting the molten resin into a die, the internal cavity pressure is momentarily reduced when the internal cavity pressure reaches a prescribed pressure, and closing of the cavity is performed so that the final thickness of the molded product is achieved, and a thin-film molded product produced is produced by said method.

Claims

1. A method of producing a thin film having a desired thickness, comprising the steps of:

(A) injecting molten resin at a first injection pressure into a cavity formed between a stationary die and a moveable die with the movable die positioned so that the cavity is opened wider than the desired thickness of the thin film; and

(B) closing the dies by moving the movable die toward the stationary die so that the cavity reaches the desired thickness and reducing the injection pressure to allow backflow of the molten resin from the cavity during the closing.

2. The method of claim 1, further comprising monitoring internal pressure within the cavity and wherein step (A) is discontinued when internal pressure within the cavity is between 200 kg/cm² to 300 kg/cm².

3. The process of claim 1, wherein the desired thickness of the film is less than 1 millimeter.