Process for producing a selectively reinforced thermoformed article

• US 5,283,028 A
• Filed: 06/30/1992
• Issued: 02/01/1994
• Est. Priority Date: 05/02/1990
• Status: Expired due to Fees

• Current Assignee: Alltrista Corporation (Newell Brands Inc.)
• Original Assignee: Penda Corporation (Kruger Family Industries, LLC)
• Inventors: Price, William F., Breezer, Harlon W.
• Primary Examiner(s): Timm, Catherine
• Application Number:
  US07/907,705
• Time in Patent Office: 581 Days
• Field of Search: 264/510, 264/511, 264/512, 264/516, 264/545, 264/247, 264/248, 264/251, 264/259, 264/261, 264/265, 264/268, 264/279.1, 156/286, 156/156, 156/228, 156/245, 156/309.9, 156/285
• US Class Current: 264/511
• 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

Reinforced twin-sheet thermoformed articles are produced by 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. Alternatively, a heated quantity of thermoplastic liquid material may be 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. The articles formed 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 twin-sheet thermoformed articles having a reinforced portion comprising the steps of:

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

(b) forming the heated first and second sheets in first and second molds respectively;

(c) heating a reinforcing insert of thermoplastic to a forming temperature at which the insert is semi-solid;

(d) placing the heated reinforcing insert of thermoplastic material on the first sheet after it has been formed in the first mold at a selected location to be reinforced; and

(e) then pressing the heated second sheet within the second mold into contact with the heated first sheet and the heated reinforcing insert within the first mold to form the reinforcing insert between the sheet so that a fusion of the thermoplastic sheets and the reinforcing insert takes place to produce a continuous integral reinforced section of the article having a desired molded shape.