Selectively reinforced thermoformed article and process

• US 5,885,691 A
• Filed: 08/23/1996
• Issued: 03/23/1999
• Est. Priority Date: 05/02/1990
• Status: Expired due to Term

• Current Assignee: Trienda Holdings, L.L.C. (Kruger Family Industries, LLC)
• Original Assignee: TriEnda Corporation (Newell Brands Inc.)
• Inventors: Price, William F., Breezer, Harlon W.
• Primary Examiner(s): Watkins, III, William P.
• Application Number:
  US08/702,360
• Time in Patent Office: 942 Days
• Field of Search: 428/156, 428/159, 428/161, 428/162, 428/172, 428/78, 428/189, 428/77, 428/68, 428/76, 428/174, 428/213, 428/166, 428/178, 108/51.1, 108/901, 108/902, 425/588, 425/504, 425/327, 264/328.1, 264/DIG. 50, 264/255, 264/261, 264/268
• US Class Current: 428/156
• 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 reinforced twin-sheet thermoformed thermoplastic article comprising:

(a) a first thermoformed thermoplastic sheet;

(b) a second thermoplastic sheet; and

(c) a quantity of solid thermoplastic material located between and fused to the first and second thermoplastic sheets at a reinforced section of the article such that the reinforced section is of greater thickness than the combined thickness of the first and second sheets at the section location, and wherein the first thermoplastic sheet is fused to the second thermoplastic sheet without an intermediate sheet at locations other than at the reinforced section of the article.

2. The article of claim 1 wherein the first sheet, the second sheet, and the quantity of thermoplastic material are all formed of the same thermoplastic material.

3. A reinforced twin-sheet thermoformed thermoplastic article comprising:

(a) a first thermoplastic sheet having at least a portion thereof thermoformed;

(b) a second thermoplastic sheet having at least a portion thereof thermoformed, wherein the thermoformed portions of the first and second sheets define a cavity; and

(c) a solid thermoplastic reinforcing insert molded to substantially the same shape as the cavity and fused to the thermoformed portions of the first and second sheets.

4. The article of claim 3 wherein the first sheet, the second sheet and the insert are all made of the same thermoplastic material.

5. The article of claim 3 wherein the first and second thermoplastic sheets are fused directly to one another in at least one location.

6. A reinforced twin-sheet thermoformed thermoplastic article comprising:

(a) a first thermoformed thermoplastic sheet formed to have an upwardly opening cavity;

(b) a second thermoformed thermoplastic sheet having downwardly extending portions which open upwardly, said downwardly extending portions overlying the upwardly opening cavity of the first sheet, wherein portions of the first sheet are fused directly to portions of the second sheet spaced from the cavity; and

(c) a quantity of solid thermoplastic material disposed within the first thermoplastic sheet cavity and fused to both the first thermoplastic sheet and the second thermoplastic sheet and molded into the shape of the cavity by the first sheet and the second sheet.

7. A reinforced twin-sheet thermoformed thermoplastic article comprising:

(a) a first thermoformed thermoplastic sheet formed to have an upwardly opening cavity;

(b) a second thermoformed thermoplastic sheet having portions which open downwardly toward said cavity, said downwardly opening portions overlying the upwardly opening cavity of the first sheet, wherein portions of the first sheet are fused directly to portions of the second sheet spaced from the cavity; and

(c) a quantity of solid thermoplastic material disposed within the cavity and fused to both the first thermoplastic sheet and the second thermoplastic sheet and molded into the shape of the cavity by the first sheet and the second sheet.