NZ272749A

NZ272749A - Process for producing panels from discrete polymeric material

Info

Publication number: NZ272749A
Application number: NZ272749A
Authority: NZ
Inventors: Brian Clifford Sullivan
Original assignee: Flight Group Ltd
Priority date: 1995-08-09
Filing date: 1995-08-09
Publication date: 1997-06-24
Also published as: AU6199196A; AU692714B2

Description

272749 PATENTS FORM NO. 5 Fee No. 4: $260.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional r No: 272749 c„, Dated: 9 August 1995 I o/ Vo Moulding Methods and Apparatus I/WE Flight Group Limited, a New Zealand company of Corner of Lady Ruby Drive and Sir William Avenue, East Tamaki, Auckland, New Zealand hereby declare the invention for which I/We pray that a patent may be granted to me/us, and the method by which it is to be performed to be particularly described in and by the following statement: 1 Moulding Methods and Apparatus Technical Field 2 / The present invention relates to the production of panels, sheets, and such like from recycled materials, such as mixed/non-mixed post consumer/industrial plastics.

BACKGROUND ART Post consumer plastics is commonly broken down by recycling companies and sold in a crushed or flaked form for various reuses. Subject to compatibility most recycled plastics can be remoulded, however the processes used to date to remould recycled plastics have limitations notably in terms of the mechanical properties of the product produced.

It is an object of the present invention to provide an improved moulding process and apparatus for reusing recycled plastics.

Further objects and advantages of the present invention will become apparent from the ensuing description which is given by way of exar pie only. disclosure of According to the present invention there is provided a process for producing a panel from discrete polymer material comprising placing a layer of discrete polymer materials of substantially even depth on a surface, compressing and heating the discrete polymer materials to form a panel and subsequently allowing the panel to cool whilst it ie clamped between opposed plates. 2 272749 The steps of heating the discrete polymer material and allowing"the panel* to cool whilst it is clamped are separate process steps.

The process can include providing a source of discrete polymer materials, feeding said discrete polyer materials onto a thermoplastics polymer film whilst subsequently or simultaneously overlaying a farther layer of thermoplastics polymer film over the discrete polymer materials to form a "sandwich" (as defined herein), compressing and heating the sandwich, and subsequently cooling or allowing cooling of the sandwich.

The discrete polymer material is in the form of flakes prepared by recycling processes.

The compressing and heating steps can be achieved using opposed heated plates.

The surface temperature of the opposed heated plates is between 190° C and 230° C.

The clamping pressure of the heating plates is at least 4.5 kg/cm2- The panel can be clamped between opposed plates and allowed to cool the surface temperature of the opposed plates being ambient temperature or less than ambient temperature.

The source of discrete polymer material is a hopper having a positive displacement valuing means which feeds the discrete polymer material onto a plastics sheet below at an even depth. 3 The present invention also provides apparatus for producing a panel by the process as aforesaid comprising a source of discrete polymer materials, heating and compression means and clamping and cooling means.

The source of discrete polymer materials, can include positive displacement means for feeding the discrete polymer material onto a film at an even depth.

The discrete materials can be heated between two opposed compressing and heating plates and subsequently conveyed to the said clamping and cooling means.

The compressing and heating plates and the clamping and cooling means can be in-line.

The compressing and heating apparatus and clamping and cooling means can be radially spaced and the panel is transported from the compressing and heating plates to the clamping and cooling means by a carousel.

The discrete polymer material to which the present invention relates is commonly known by the term "polyflak", and is available in New Zealand from Plastics Recyclers of Auckland New Zealand. The polymer material is made from waste containers and other plastics objects which would otherwise go to land fills. The process of making the polyflak involves breaking down into flakes plastics containers and other plastics objects in a crushing apparatus which are then screened, washed in a solution of water and caustic soda (or similar). The washing process removes, labels, oils, adhesives and the like and the washed flakes are then dried and bagged usually using a centrifuge apparatus. 272749 Brief Description of Drawings Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1&2 are diagrammatic sketches showing distinct process steps of the present invention, and; Figure 3 is a side view of one possible arrangement of for compressing and heating the sandwich, and Figure 4 is a diagrammatic sectional view of one possible form of hopper for storing and dispersing discrete polymer materials, and Figure 5 is a schematic layout drawing of another possible form of apparatus in accordance with the present invention, and Figure 6 is a diagrammatic side view of another possible form of apparatus in accordance with the present invention, and Figure 7 is a diagrammatic side view of another possible form of apparatus of the present invention, and Figures 8 & 8a are diagrammatic sectional views of a moulding method in accordance with yet another aspect of the present invention. best modes for carrying out the invention With respect to figures 1 to 3 of the drawings in one aspect of the present invention there are three process steps being; o7 L- <- l A forming a "sandwich," B compressing and heating, and C Cooling The formation of a sandwich involves feeding discrete polymer material from a hopper 1, onto a lower layer of plastics film 2 whilst simultaneously thereafter overlaying a top layer of plastics film 3 over the discrete polymer material to form a sandwich.

The sandwich is then advanced directly (or indirectly via a transfer device) to a compression and heating device generally indicated by arrow 4.

Advancement of the sandwich may be achieved by nipping the edges of the plastics film using reciprocating grippers 5.

A hot wire can be used to cut of a portion of the sandwich prior to transfer from situation A.

Compressing and heating means 4 can comprise two opposed plates 6, means for advancing and opening the plates (not shown).

Mechanical means (not shown) may be provided for interposing heat resistant sheet material 7 between each plate 6 so that the plastic film materials do not stick to the plates and a suitable material for this is silicone coated fibreglass.

Alternatively a suitable sheet material 7 or coating may be permanently or semi-permanently fixed to the surfaces of the plates 6. 272749 The next step is to transfer the moulded sandwich to a cooling device which may comprise two opposed closable plates as indicated.

It is important that the discrete polymer material is laid evenly on the lower layer of plastics film 2 and one device for achieving this is illustrated by figure 4. At the mouth of hopper 1 a fluted anger 8 is provided, this arrangement providing positive disbursement of materials from the hopper 1. Increasing or decreasing the layer thickness is merely a matter of controlling the speed of a drive motor and transmission means 9.

The manufacturing process described produces a panel from the discrete material sandwich which is rigid yet bendable, which produces a substantially non-slip surface, and depending on the raw materials used, and be made in many and varied colours. Trials to date have indicated that at the compression and heating stage the surface temperature of the opposed heating plates should be in the range of 190°C to 230°C. We have successfully provided panels of 1000 mm x 1200 mm by 2.5 mm to 8 mm deep at these temperatures.

During the cooling phase the surface temperature of the opposed cooling plates of the cooling device can be ambient temperature or below.

The heating temperatures described fully melt the discrete polymer materials and integrate the plastic film with the discrete materials to the extent that the panel is homogenous and the film layers remain a barrier to moisture.

The panels may vary in thickness and area and the clamping pressure of the heating plates can be adjusted accordingly. 27 2 7 In some instances, depending on end-user requirements, a panel may be formed without one or both of the plastic film layers. In any event the step of clamping the formed panel whilst cooling to or allowing it to cool is essential to the process. If the panel was allowed to cool whilst being unrestrained it would, because of the random nature of the recycled material, twist and bend to the point where it was useless.

Figure 5 of the drawings illustrates how the process of the present invention can be performed within a restricted area using a carousel apparatus which provides support for the discrete material for loading, compression and heating to form a panel clamping and cooling the panel and finally unloading as the carousel rotates through ninety degree intervals.

Some thought has been given to other means of automating the process in accordance with the present invention and one possibility is illustrated by figure 6. Upper and lower continuous conveyers 10, 11 convey the sandwich to separate compression and heating stations and then on to a cooling station. The conveyor belts may be formed from a continuous stainless steel sheet material which may be surface treated or layered to provide a non-stick surface.

Figure 7 of the drawings illustrates another possible form of apparatus for performing the process of the present innovation. A continuous conveyor 12 is provided with a series of open moulds 13 which are loaded with discrete material and conveyed to a heating and compression position at 14 and subsequently to a clamping and cooling position at 15. Cooled product 16 can be released, from the end of the conveyor. 8 272749 Figures 8 and 8a of the drawings illustrate how the process of the present invention may be used to form mouldings such as V-section mouldings. A predetermined quantity of discrete material is loaded into a V-mould 17 (figure 8), a complementary mould plate 18 is advanced on the material, the material compressed and heated (figure 8a) and then in a subsequent step (not shown) the moulded product can be clamped and cooled between complementary V-shaped plates. Plate ends 19 capture and restrain the discrete material during the compression and heating step.

The process of the present invention produces a product from recycled materials which exhibits greatly improved mechanical qualities, and the plastics film provides a barrier to the core of the finished product which is an important factor in food contact situations and this characteristic largely expands potential uses for such a product.

The materials used are sub-standard for other uses, all grades of plastic can be used and not just selected grades. Other fillers such as non-ferrous products and metals may be used in combination with the discrete polymer materials.

Projected uses of the panels produced in accordance with the present invention are as boards, mats, panels for placing over pallets, and as leak proof panels for the packaging and transportation industries in general and protective corner pieces.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof, as defined in the appended claims. 9 27 ? 7/f 9

Claims

WHAT WE CLAIM IS:

A process for producing a panel from discrete polymer material comprising placing a layer of discrete polymer materials of substantially even depth on a surface of a compressing and heating apparatus, compressing and heating the discrete polymer materials to form a panel removing the panel from the compressing and heating apparatus and then clamping the panel whilst allowing it to cool.
A process as claimed in claim 1 comprising providing a source of discrete polymer materials, feeding said discrete polymer materials onto a thermoplastics polymer film whilst subsequently or simultaneously overlaying a further layer of thermoplastics polymer film over the discrete polymer materials to form a "sandwich" (as defined herein), compressing and heating the sandwich, and subsequently cooling or allowing cooling of the sandwich.
A process as claimed in claim 1 or claim 2 wherein the discrete polymer material is in the form of flakes prepared by recycling processes.
A process as claimed in any one of claims 1 to 3 wherein compressing and heating step is achieved using opposed heated plates.
The process of claim 4 wherein the surface temperature of the opposed heated plates is between 190° C and 230° C. 272749
6. The process of claim 5 wherein the clamping pressure of the heating plates is at least 4.5 kg/cm2-
7. A process as claimed in any one of claims 1 to 6 wherein when the panel is clamped between opposed plates and allowed to cool the surface temperature of the opposed plates being ambient temperature or less than ambient temperature.
8. A process as claimed in any one of claims 2 to 7 wherein the source of discrete polymer material is a hopper having a positive displacement valving means which feeds the discrete polymer material onto a plastics sheet below at an even depth.
9. Apparatus for producing a panel by the process of any one of claims 1 to 8 comprising a source of discrete polymer materials, heating and compression means and clamping and cooling means.
10. Apparatus as claimed in claim 9 wherein the source of discrete polymer materials includes positive displacement means for feeding the discrete polymer material onto a film at an even depth.
11. Apparatus for producing panels by the process of any one claims 1 to 8 wherein the discrete materials are heated between two opposed compressing and heating plates and subsequently conveyed to the said clamping and cooling means.
12. Apparatus as claimed in claim 11 wherein the compressing and heating plates and the clamping and cooling means are in line. /' , ~ 5 MAY 1997 :j Vi /J 11 * 272 749
13. Apparatus as claimed in claim 11 wherein the compressing and heating apparatus are radially spaced and the panel is transported from the compressing and heating plates to the clamping and cooling means by a carousel.
14. A process for producing a panel form discrete polymer materials substantially as herein described with reference to the accompanying drawings.
15. A process for producing a panel from discrete polymer materials substantially as herein described with reference to the accompanying drawings. Flight Group Limited by its Attorneys END OF CLAIMS 12