AU2008202560A1

AU2008202560A1 - Apparatus and Method for Expanding Foams and Formation of Expanded Foam Articles

Info

Publication number: AU2008202560A1
Application number: AU2008202560A
Authority: AU
Inventors: David Allan Roud
Original assignee: OBIE PRODUCTS Ltd
Current assignee: OBIE PRODUCTS Ltd
Priority date: 2007-06-14
Filing date: 2008-06-11
Publication date: 2009-01-08
Also published as: WO2008153417A1

Description

11/06/2008 11:37 6444965949 EVT LAW PAGE 05/20 PAJO/011 Regulation 3,2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application No.: Application Date: Priority Dates: Applicants Address for Service: 11 June 2008 14 June 2007- NZ555880 Obie Products Limited PO Box 13192 Christchurch New Zealand ELLIS j VER5OEKET I TERRY PO Box 202 Hurstville BC New South Wales 1481

AUSTRALIA

Complete Specification for the invention entitled: "Apparatus and Method for Expanding Foams and Formation of Expanded Foam Articles" The following statement is a full description of this invention, including the best method of performing it known to me: COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/09/2008 11:37 6444965949 EVT LAW PAGE 06/20 SAPPARATUS AND METHOD FOR EXPANDING FOAMS AND FORMATION OF EXPANDED FOAM ARTICLES FIELD OF THE INVENTION O The invention relates to expansion of foams and to formation of expanded foam articles.

o BACKGROUND TO THE INVENTION 00 0 10 Polyolefin foam is generally expanded from flat preformed sheets in a one or two stage 01 process. The flat sheets are heated in a mould, activating a decomposable, gasreleasing blowing agent. This causes the preformed sheets to expand to approximately times their original volume.

In a two-stage process, preformed sheets are partially expanded in a first mould, before being fully expanded in a second mould. The two-stage process limits the stresses caused In the foam structure during the expansion process. Unrestrained flat sheets would distort during the expansion process, so expansion must be carded out in restraining moulds.

Previous moulds are generally planar in form. However, this requires the use of strong materials and powerful hydraulic systems in the moulds. This makes the machinery costly and inefficient.

Expanded foam is usually cut or further processed following the expansion process. To form non-planar objects, sheets of foam may be glued together and shaped, resulting in significant wastage, It is an object of the invention to provide an improved foam expansion apparatus and/or method, or at least to provide the public with a useful choice.

2 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 07/20 00 SSUMMARY OF THE INVENTION In a first aspect the invention provides a method of forming an article by expanding foam, including the steps of: introducing unexpanded foam into an elongate, tubular chamber with an uninterrupted 0 bore; partially expanding the foam in the elongate chamber; O introducing the partially expanded foam into a second chamber having a shape 0C corresponding to the desired shape of an article to be formed; 0 10 expanding the partially expanded foam in the second chamber.

In a second aspect the invention provides a method of expanding foam, including the steps of: partially expanding foam in a first expansion chamber; introducing the partially expanded foam into a second expansion chamber of non-planar form; further expanding the partially expanded foam in the second expansion chamber.

In a third aspect the invention provides an apparatus for expansion of foam, including: an elongate, tubular chamber having an uninterrupted bore, a first end and a second end; a first closure configured to move into and out of the first end of the tubular chamber, to block the first end during expansion and to allow removal of expanded foam; and a second closure configured to block the second end of the tubular chamber during expansion and to move through the chamber from the second end towards the first end to push expanded foam out of the chamber at the first end.

In a fourth aspect the invention provides a method of forming expanded foam sheet, including: expanding foam in a cylindrical mould to form a cylinder of expanded foam; turning the expanded foam cylinder about its axis; using a blade to cut the expanded foam cylinder into expanded foam sheet as it turns.

3 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 08/20 00 BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only, with reference to the accompanying drawings, in which: O Figure 1 shows a foam expansion apparatus in a closed position; iN Figure 2 shows the foam expansion apparatus of Figure 1, in an open position; 0 10 Figure 3 shows a cross-section of one embodiment of expansion chamber; 0 Figure 4 shows a cross-section of another embodiment of expansion chamber; Figure 5 shows a cross-section of a further embodiment of expansion chamber; Figure 6 shows an expanded foam article; and Figure 7 shows a method of forming expanded foam sheet from an expanded foam cylinder.

DETAILED DESCRIPTION Figures 1 and 2 show a foam expansion apparatus 1. The apparatus includes an elongate, tubular chamber 2, formed by an inner wall 3. An outer wall 4 is also provided, and the space between the inner and outer walls contains a number of heating elements for heating the chamber to a desired temperature.

The apparatus 1 also includes a first closure 6 which is configured to move into and out of a first end 7 of the chamber 2. This closure closes the first end 7 during expansion of foam in the chamber 2 (as shown in Figure 1) and opens the first end 7 when expansion is complete (as shown in Figure 2) to allow expanded foam to be removed. The first closure 6 may be mounted on a first ram 8, such as a hydraulic ram or similar.

4 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 09/20 00 0 0 ci The apparatus I includes a second closure 10, which closes the second end 11 of the Schamber 2 during expansion of foam, as shown in Figure 1. When expansion is complete, the second closure 10 moves through the chamber 2 from the second end 11 towards the first end 7, in order to push expanded foam out of the chamber 2 through the first end 7. The second closure 10 may be mounted on a second ram 12, such as a Ohydraulic ram or similar.

o During expansion of foam, the first closure 6 may be moved from a position within the 00 chamber (Figure 1) towards the first end 7 without actually passing out of the chamber 2.

o 10 This increases the effective volume of the chamber 2 during expansion, thereby Ci controlling the expansion process. This movement may be achieved by driving the first ram 8 in an appropriate manner, or simply by making the ram 8 movable in response to the increasing pressure generated in the chamber 2. This increase in volume could also be achieved by moving the second closure, or both closures.

The elongate tubular chamber may have a circular cross-section (Figure forming a cylindrical chamber. This shape is preferred as it has a natural strength, making it more suitable for withstanding the high pressures created during expansion.

However, other tubular configurations may be used, such as chambers with elliptical (Figure square (Figure 5) or rectangular cross-sections. In general, any crosssectional shape may be used, but preferably the cross-section is uninterrupted by internal elements.

The elongate, tubular chamber may be used for partial expansion of foam or final expansion of foam, where a two stage expansion process is used.

For partial expansion of foam, the chamber 2 may be heated using the heating elements to a temperature between about 150 to 1650 Celsius, preferably about 1600 Celsius.

This temperature may be maintained for a time period of about 30 to 60 seconds per mm of diameter of the chamber. Preferably the temperature is maintained for a time period of about 45 to 55 seconds per mm of diameter of the chamber, more preferably about seconds.

COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 10/20 00 O0 0 Z Where this chamber is used for partial expansion of foam, the resulting partially _expanded foam may be introduced into a second chamber for further expansion. The second chamber may be of non-planar form and may have an internal shape which corresponds to the desired shape of an article to be formed. Thus, a substantially O finished article is produced by expanding foam in a mould, This is in contrast to previous tfa methods, in which expanded mould was generally cut or otherwise worked after Sexpansion. The Applicant's method allows the use of recycled foam materials, since the Noutside surface of the article is formed during the expansion process. This means that 00 10 any recycled materials are generally contained within the article and any lack of Ouniformity is generally concealed within the article. Prior methods did not allow this, since cutting of the expanded material would reveal any lack of uniformity caused by recycled material in the expanded foam, The second chamber may be heated to a temperature about 100 Celsius higher than the temperature used for partial expansion.

The second chamber may be shaped to produce an article such as that shown in Figure 6, This is a buoy 60, formed from foam expanded in a second chamber having a corresponding shape. The buoy is roughly rugby-ball shaped in a cross-section along its length, pointed at its two ends 61, 62, such that it has a low resistance to fluid flow along its length.

The second chamber may be shaped for moulding of any suitable article, including: boat fenders, exercise devices, flotation aides, buoys, impact buffers etc.

Figure 7 shows a cylinder 70 of expanded foam being formed into layers of foam. The cylinder may be formed using either of the chambers described above. The cylinder is turned around its axis as indicated by arrow 71. A blade 72 is mounted so as to cut a strip of the foam from the cylinder 70. The blade is preferably movable as indicated by arrow 73, such that a continuous layer or a series of layers of foam can be formed from the cylinder. This method enables a very long continuous stock of thin foam to be produced which is particularly suited to packaging applications etc. Where this method COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444955949 EVT LAW PAGE 11/20 00 0 0 is used, it may be preferable to use all new materials, since any lack of uniformity will be ;Z revealed by the cutting operation.

The foam material may included recycled or new material, and may include polyolefin material, particularly cross-linkable polyolefin material, low density polyethylene material 0 and/or ethylene vinyl acetate material. Other materials may also be suitable. In general l^ these materials are mixed with an expanding blowing agent before expansion.

0 K 0The methods and apparatus described above allow production of substantially finished o 10 articles, with very little waste. Recycled plastics may be used. The expansion chamber Sis also a simple and strong structure.

While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described.

Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicants general inventive concept.

7 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11

Claims

2. A method as claimed in claim 1 wherein the elongate, tubular chamber is a cylindrical chamber.
3. A method as claimed in claim 1 wherein the elongate, tubular chamber has an oval cross-section.
4. A method as claimed in any preceding claim, including: v. closing the elongate, tubular chamber before partially expanding the foam, using a first closure at a first end of the elongate, tubular chamber and a second closure at a second end of the elongate, tubular chamber; vi. opening the elongate, tubular chamber at its first end after partially expanding the foam, by removing the first closure; and vii. forcing the partially expanded foam from the elongate, tubular chamber by moving the second closure through the elongate, tubular chamber from its second end towards its first end. A method as claimed in claim 4 including operating the second closure using a ram.
6. A method as claimed in claim 4 or 5 including operating the first closure using a ram.
7. A method as claimed in any one of claims 4 to 6 including moving at least one of the closures during the partial expansion so as to increase the operating volume of the elongate, tubular chamber. 8 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 13/20 00 0 0
8. A method as claimed in any preceding claim including heating the elongate, tubular Schamber to a temperature between about 150 to 1650 Celsius during partial expansion of the foam. O 9. A method as claimed in any claim 8 including heating the elongate, tubular chamber l^ to a temperature of about 160° Celsius during partial expansion of the foam. Cl 10. A method as claimed in any preceding claim including partially expanding the foam 0 10 over a time period of about 30 to 60 seconds per mm of diameter of the elongate, tubular o chamber.
11. A method as claimed in any claim 10 including partially expanding the foam over a time period of about 45 to 55 seconds per mm of diameter of the elongate, tubular chamber.
12. A method as claimed in any claim 11 including partially expanding the foam over a time period of about 50 seconds per mm of diameter of the elongate, tubular chamber.
13. A method as claimed in any preceding claim wherein the unexpanded foam includes recycled material.
14. A method as claimed in any preceding claim wherein the unexpanded foam includes crosslinkable polyolefin material. A method as claimed in any preceding claim wherein the unexpanded foam includes low density polyethylene material.
16. A method as claimed in any preceding claim wherein the unexpanded foam includes ethylene vinyl acetate material.
17. A method as claimed in any preceding claim wherein the second chamber is shaped to produce a finished article shaped for low resistance to fluid flow. 9 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 14/20 00 0 0 1 18. A method of expanding foam, including the steps of: i. partially expanding foam in a first expansion chamber; ii. introducing the partially expanded foam into a second expansion chamber of non-planar form; and iii. further expanding the partially expanded foam in the second expansion chamber. O Vn 19. A method as claimed in claim 18 wherein the second expansion chamber has a Sshape corresponding to the desired shape of an article to be formed. 00 S 10 20. A method as claimed in claim 18 or 19 wherein the second chamber is shaped to Sproduce a finished article shaped for low resistance to fluid flow.
21. A method as claimed in any one of claims 18 to 20 wherein the first expansion chamber is an elongate, tubular chamber with an uninterrupted bore.
22. A method as claimed in any one of claims 18 to 21 wherein the unexpanded foam includes recycled material,
23. A method as claimed in any one of claims 18 to 22 wherein the unexpanded foam includes crosslinkable polyolefin material.
24. A method as claimed in any one of claims 18 to 23 wherein the unexpanded foam includes low density polyethylene material.
25. A method as claimed in any one of claims 18 to 24 wherein the unexpanded foam includes ethylene vinyl acetate material.
26. An apparatus for expansion of foam, including: i. an elongate, tubular chamber having an uninterrupted bore, a first end and a second end; ii. a first closure configured to move into and out of the first end of the tubular chamber, to block the first end during expansion and to allow removal of expanded foam; and COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 15/20 00 0 0 S iii. a second closure configured to block the second end of the tubular chamber Z during expansion and to move through the chamber from the second end Stowards the first end to push expanded foam out of the chamber at the first end.
27. An apparatus as claimed in claim 26 wherein the elongate, tubular chamber is a 0 cylindrical chamber. NO S28. An apparatus as claimed in claim 26 wherein the elongate, tubular chamber has an Cl oval cross-section. 00 o o 29. An apparatus as claimed in any one of claims 26 to 28 including a first ram configured to move the first closure into and out of the first end of the elongate, tubular chamber.
30. An apparatus as claimed in any one of claims 26 to 29 including a second ram configured to move the second closure through the chamber from the second end towards the first end.
31. An apparatus as claimed in any one of claims 26 to 30 wherein at least one of the closures is configured to move during the expansion so as to increase the operating volume of the elongate, tubular chamber.
32. An apparatus as claimed in any one of claims 26 to 31 including a heater for heating the chamber, thereby causing expansion of foam within the chamber.
33. A system for forming an article by expanding foam, including an apparatus as claimed in any one of claims 26 to 32 and a second chamber for receiving foam partially expanded in the elongate, tubular chamber and having a shape corresponding to the desired shape of an article to be formed.
34. A method of forming expanded foam sheet, including: expanding foam in a cylindrical mould to form a cylinder of expanded foam; turning the expanded foam cylinder about its axis; using a blade to cut the expanded foam cylinder into expanded foam sheet as it turns. 11 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11 11/06/2008 11:37 6444965949 EVT LAW PAGE 16/20 A method as claimed in claim 1 or 18 substantially as herein described.
36. An apparatus as claimed in claim 26 substantially as herein described.
37. An apparatus for expansion of foam substantially as herein described with reference to any embodiment shown in Figures 1 to 5 of the accompanying drawings. 12 COMS ID No: ARCS-193915 Received by IP Australia: Time 09:57 Date 2008-06-11