Twin-sheet thermoforming process with shell reinforcement

• US 5,635,129 A
• Filed: 06/06/1995
• Issued: 06/03/1997
• Est. Priority Date: 05/02/1990
• Status: Expired due to Fees

• Current Assignee: Alltrista Corporation (Newell Brands Inc.)
• Original Assignee: TriEnda Corporation (Newell Brands Inc.)
• Inventors: Price, William F., Breezer, Harlon W.
• Primary Examiner(s): WATKINS III, WILLIAM P
• Application Number:
  US08/466,325
• Time in Patent Office: 728 Days
• Field of Search: 264/511, 264/544, 264/545, 264/263, 264/320, 264/324, 264/553, 264/554, 264/154, 264/261
• US Class Current: 264/553
• CPC Class Codes: B29C 2045/14532 injecting between two sheets
• CPC Class Codes: B29C 2049/2017 outside the article
• CPC Class Codes: B29C 2791/006 Using vacuum
• CPC Class Codes: B29C 43/183 the preformed layer being a lining, e.g. shaped in the mould before compression moulding, or a preformed shell adapted to the shape of the mould
• CPC Class Codes: B29C 43/206 by pressing the material between two preformed layers, e.g. deformable layers
• CPC Class Codes: B29C 43/34 Feeding the material to the mould or the compression means B29C43/085 takes precedence
• CPC Class Codes: B29C 45/00 Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor injection blow-moulding B29C49/06
• CPC Class Codes: B29C 45/14467 Joining articles or parts of a single article B29C45/14377, B29C45/14385, B29C45/14581, B29C45/14614 and B29C45/006 take precedence
• CPC Class Codes: B29C 49/20 of articles having inserts or reinforcements ; Handling of inserts or reinforcements
• CPC Class Codes: B29C 51/00 Shaping by thermoforming , i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor blow moulding of tubular preforms B29C49/00, deforming of tubular or hollow preforms B29C67/0014
• CPC Class Codes: B29C 51/10 Forming by pressure difference, e.g. vacuum
• CPC Class Codes: B29C 51/267 Two sheets being thermoformed in separate mould parts and joined together while still in the mould B29C49/0691 takes precedence
• CPC Class Codes: B29C 69/02 of moulding techniques only
• CPC Class Codes: B29K 2995/0097 Thickness
• CPC Class Codes: Y10S 108/901 Synthetic plastic industrial platform, e.g. pallet
• CPC Class Codes: Y10S 108/902 Made with deformable integral fastening elements
• CPC Class Codes: Y10S 264/50 Use of fluid pressure in molding
• CPC Class Codes: Y10T 428/23 Sheet including cover or casing
• CPC Class Codes: Y10T 428/239 Complete cover or casing
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/24504 : Component comprises a polymer [e.g., rubber, etc.]
• CPC Class Codes: Y10T 428/24521 : with component conforming to contour of nonplanar surface
• CPC Class Codes: Y10T 428/24529 : and conforming component on an opposite nonplanar surface
• CPC Class Codes: Y10T 428/24562 : Interlaminar spaces
• CPC Class Codes: Y10T 428/24612 : Composite web or sheet
• CPC Class Codes: Y10T 428/24628 : Nonplanar uniform thickness material
• CPC Class Codes: Y10T 428/24661 : Forming, or cooperating to form cells
• CPC Class Codes: Y10T 428/24752 : Laterally noncoextensive components
• CPC Class Codes: Y10T 428/2495 : Thickness [relative or absolute]

Abstract

A process is disclosed for producing reinforced twin-sheet thermoformed articles comprising the steps of heating first and second sheets of thermoplastic material; forming the sheets in molds; heating a reinforcing insert of thermoplastic material; placing the heated insert on the first sheet in its mold at the location to be reinforced; pressing the second sheet into contact with the heated first sheet and the heated insert to form the insert between the sheets so that a fusion of the thermoplastic sheets and the insert takes place to produce a reinforced section of the article having a desired shape and thickness. Alternative processes are disclosed wherein a heated quantity of thermoplastic liquid material is extruded or injected between the first and second sheets within the first and second molds either by inserting the liquid material before the molds are closed or by injecting it through one of the molds. Also disclosed are twin-sheet thermoformed articles with reinforced sections which are thicker than the combined thicknesses of the two thermoformed sheets at a particular location. The articles may advantageously be reinforced with plastic identical to the plastic of the two sheets. The articles are also easily recycled as they are entirely plastic with no non-plastic matter included.

Claims

1. A process for producing a reinforced twin-sheet thermoformed thermoplastic article having a reinforced portion, the process comprising the steps of:

(a) heating first and second sheets of thermoplastic material;

(b) forming the first sheet in a first mold;

(c) forming the second sheet in a second mold;

(d) pressing the heated second sheet in the second mold into contact with the heated first sheet in the first mold such that the two sheets are fused together at selected areas of contact and mate to form a hollow cavity at a selected reinforced location; and

(e) injecting under pressure a quantity of liquid thermoplastic material through at least one of the molds and one of the sheets into the cavity to substantially fill the cavity with thermoplastic material so that the quantity of liquid thermoplastic material fuses with the two sheets defining the cavity to form an article having a continuous integral reinforced portion of a desired shape and thickness at the selected reinforced location.

2. The process of producing a reinforced thermoplastic article having a reinforced portion of claim 4, wherein the first sheet, the second sheet, and the quantity of liquid thermoplastic material are all formed of the same thermoplastic material.