WO1998019853A1

WO1998019853A1 - Apparatus and process for the production of solid surface material articles

Info

Publication number: WO1998019853A1
Application number: PCT/AU1997/000733
Authority: WO
Inventors: Trevor Edward Holloway
Original assignee: Chem Form Pty. Limited
Priority date: 1996-11-01
Filing date: 1997-10-31
Publication date: 1998-05-14
Also published as: AUPO339196A0

Abstract

A method of moulding an article comprises partially filling a horizontally positioned mould with a flowable settable material, inclining the mould and applying a partial vacuum to draw out bubbles of gas entrained in the material.

Description

APPARATUS AND PROCESS FOR THE PRODUCTION OF SOLID SURFACE

MATERIAL ARTICLES Technical Field

This invention concerns an apparatus and a process for the production of solid surface material articles. Solid surface material is a synthetic manufactured material that is impervious, and will not hold bacteria. Solid surface material is colour consistent throughout and does not need coating, it may be provided in a range of attractive textured finishes. Its main purpose is for use as industrial bench tops or work surfaces, but it can be used for a wide range of applications due to its durable smooth surface.

Solid surface material is made from a combination of polymeric resin or acrylic resin coupled with chemical resistant and fire retardant natural mineral fillers, along with colour pigments and sometimes other special elements. Background Art

Solid surface material is sometimes cast as a finished product such as a furniture item, say a vanity, or more commonly, is cast as a flat sheet and then fabricated into the required shape. The material is workable, depending on the skill of the fabricator, into any required shape by cutting, routing or sanding. As solid surface material is the same material throughout, the top surface can be cut away, and then sanded and polished to the same surface finish. The material may be glued using adhesives made to the same or similar formula as the material itself, thus giving an almost seamless joint. Many layers of solid surface material can be joined together, then cut into various shapes and finished to give an appearance of one moulded product.

Solid surface material can be used with other materials and can be inlaid using a router to create a recess that is filled with liquid colour inlay

Currently, solid surface material articles are expensive since the fabrication costs can equal the cost of the material, or even exceed it where complicated shapes are concerned, due to the high amount of wasted material. The high cost effectively limits the shapes of the articles that can be produced from the material. There are also limits to the colours and textures in which sheets of the material are manufactured.

Summary of the Invention Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

A first aspect of the invention, as currently envisaged, provides an apparatus for the production of a solid surface material article, comprising a mould and a production platform for supporting the mould during movement of the mould between spread apart locations during a moulding process, the mould comprises upper and lower parts which, when held together, define a cavity having the shape of the article, the production platform, in a first orientation provides support in the lower part of the mould to receive a flowable settable solid surface material and in a second orientation, provides support for the mould when inclined after the parts are joined and means for evacuating gases from the interior of the closed mould when in the inclined orientation. Formations can be provided on the mould, the production platform or both, to enable the mould to be moved horizontally on the platform while it is in both the first and second orientations.

The lower part of the mould will frequently be rectangular in shape with a flat bottom and low sidewalls. The upper part will frequently be flat. The interiors of both parts are shaped to form the cavity and may be coated with a suitable release agent.

The production platform may have a bed of rollers to enable the mould to be supported and moved generally horizontally. At least one of the parts of the mould may have wheels or rollers along one edge to enable it to be rolled horizontally with respect to the production platform when it is in the second orientation.

Part of the production platform may be tilted between the first and second orientation and the platform may also include a track along which the wheels, or rollers, engage, and then run when in its second orientation. The means for evacuating gases may include a vacuum port that communicates with a free edge of the cavity when containing the settable material. Windows may be incorporated into the mould to enable observation of the interior of the mould during evacuation.

In a second aspect, as currently envisaged, the invention provides a method of forming an article of solid surface material comprising pouring a fluid settable mixture of the material into a horizontally oriented mould to at least partially fill the mould, closing the mould then inclining the closed mould, applying a partial vacuum to the interior of the closed mould while in the inclined position, curing the mixture in the closed mould to a stage where the moulded article can be removed from the mould for further processing.

One embodiment of the method of the invention comprises, preparing a liquid resin mixture; placing the lower part of a mould on a production platform; pouring a measured volume of the prepared liquid resin mixture into the lower part of the mould; closing the mould by placing an upper part over the lower part to define a cavity within the mould containing the mixture, the cavity having the shape of the article with the exception of one free edge, and the total volume of the cavity being greater than the volume of mixture; tilting the closed mould to cause the mixture to flow under the influence of gravity and leave an air space above it; evacuating the air space; and curing the mixture to form the article.

The process may enable a manufacturer to mould a wide range of finished articles without the need for fabrication. The mould is advantageously tilted until the mould is almost vertical. Tilting the mould and applying a vacuum may aid settlement of the material and extract air bubbles, it may also produce articles that are free from warping and other stress problems. Mixing pigmented resins may enable the creation of coloured effects in the surface, or throughout, the material. The insertion of textured materials below the surface of the resin may enable the creation of textured effects in the material.

Brief Description of the Drawings An example of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of apparatus embodying the invention at a first stage of a process for producing a solid surface material article;

Figure 2 is an isometric view of apparatus embodying the invention at a second stage of a process for producing a solid surface material article; Figure 3 is an isometric view of part of an apparatus embodying the invention in a first configuration;

Figure 4 is an isometric view of the part of the apparatus of figure 3 in a second configuration; Figure 5 is an isometric view of the apparatus of figure 3 at a third stage of the process;

Figure 6 is an isometric view of the apparatus of figure 4 at a fourth stage of the process;

Figure 7 is an isometric view of apparatus embodying the invention at a fifth stage of the process;

Figure 8 is an isometric view of apparatus embodying the invention at a sixth stage of the process;

Figure 9 is an isometric view of apparatus embodying the invention at a seventh stage of the process; and Figure 10 is an isometric view of apparatus embodying the invention at an eighth stage of the process.

The same reference numbers have been used throughout the drawings to refer to corresponding elements.

Best Modes for Carrying out the Invention Referring to the figures the apparatus comprises a mould, indicated generally at 1, and a production platform, indicated generally at 2, on which the mould 1 is moved between the positions required during the production process.

The mould 1 comprises an upper 3 and a lower 4 part that, when joined, define a cavity 5 having the shape of the article 6 except for one free edge 7.

The production platform 2, in a first configuration shown in figures 1, 2, 3, and 5, provides support for the lower part 4 such that it is able to contain liquid 8 in its part cavity when the upper part 3 is not present. The production platform 2, in a second configuration shown in figures 4,6,7,8 and

9, provides support for the mould 1, when the parts 3 and 4 are joined, such that the free edge 7 is uppermost. The production platform 2 is configurable between the first and second configurations while supporting the mould 1. Rollers 9 on the production platform 2 enable the mould 1 to be moved horizontally on the platform 2 while it is in the first configuration. The lower part 4 of the mould 1 is rectangular in shape with a flat bottom 10 and low side walls 11. The upper part 3 is flat. The interiors of both parts are shaped to form the cavity 5 and may be coated with a suitable release agent. The lower part 4 of the mould 1 has wheels 12 along one edge to enable it to be rolled horizontally with respect to the production platform 2 when it is in the second configuration.

The upper part of the mould includes a vacuum port 20 which communicates with the free edge 7 of the cavity 5. Windows 13 are incorporated into the mould 1 to enable observation of the interior of the mould during evacuation.

The production platform includes a tilt table 14, shown in detail in figures 3 and 4. Along one edge the tilt table includes a track 15 that captures the wheels 12 of the mould when the mould is rolled along the platform to the tilt table. The entire surface of the tilt table, including the rollers 9 and the rail 15 may be pivoted about axis 16 between the horizontal configuration shown in figure 3 and the tilted configuration shown in figure 4.

The process by which a solid surface material article is produced is a 'thermal set process'. This means that all the ingredients of the end product are mixed together in a liquid form, and a catalyst is added immediately before the article is cast (Figure 1), in order to cause it to set into a rigid article 6.

Polyester resins, alumina fillers, pigments, and any other additives are measured using accurate scales. The fillers chosen not only saturate and fire retard the resin but also wet out completely within the resin. Combined with this the pigments that are made have the same resin base as the main resin to give a consistent mix throughout.

The ingredients are mixed in a standard 225 litre drum that is moved and poured using a standard drum lifter. The drums are fitted with plastic drum liners to reduce the time and cost of cleaning.

The mixer has a three-phase fire-proof motor, and is mounted on an air ram that enables it to be raised and lowered over the drum. The mixer is controlled with a fire-proof variable speed switch to ensure complete control of the mixing process as the ingredients are added. The mixer is fitted with a stainless steel impeller and shaft that is designed to force the mix down the centre of the drum and out to the sides. This makes the equipment easy to clean and ensures that the liner does not become entangled with the mixer.

The shape of the impeller is designed to completely mix the ingredients by turning over the mix while generating the minimum amount of air bubbles. Mixing the catalyst evenly throughout the mix causes it to catalyse totally throughout the mix. Even catalysis ensures the mix will gel evenly and that the end product will be stress free.

The mould's upper 3 and lower 4 parts are preheated prior to the mix being poured to stop the mould drawing any heat out of the mix and to give control over the thermal process.

The sheets are cast horizontally into the lower part 4 of an open mould 1 on a conveyer table 2, which enables the mould to be moved backwards and forwards as the mix flows into the mould. In this way it is possible to ensure that the mix is poured into the mould evenly and quickly without trapping large pockets of air. When unusual shapes are to be cast the pouring process may vary as the mould shape requires, but generally the mix is cast in one evenly flowing pour.

Since the mould is relatively flat and positioned in a horizontal position during the pour, any small amounts of air rise quickly to the surface and escape prior to the mould being closed. A horizontally positioned mould also enables artwork to be effected on the surface of the article during or immediately after pouring the casting mix.

The mould 1 is then moved along the conveyer table 2 (Figure 2) and the upper part 3 is added and the mould closed (Figure 5). The upper part 3 of the mould 1 has a portion of a drum fitted (not shown) to enable it to be handled by a drum lifter.

The mould 1, which can weigh up to 500 kg when filled, is then moved onto tilting table 14. which tilts the mould 1 to an almost vertical position (Figure 6). In this position the mould 1 is connected to a vacuum system to evacuate the air in the space above the free edge of the resin, and thereby remove any air that may be trapped in the mix, The evacuation process may be monitored through the windows 13 in the mould.

The use of a tilting table enables a predetermined weight of resin mix to be poured into the mould to make a particular size (width) of sheet. So, only one size of mould is required to make a variety of sheet widths and there is little wastage of material. By tilting the mould, the settlement problems that are normally associated with horizontal casting, that is warpage, inconsistent texture, and air bubbles on the back of the sheet, are ameliorated. As the mould is not tilted exactly to the vertical and the mix is quite heavy, any impurities that may have got into the mix or mould will rise to one side giving the sheet a good clear front or top face.

The mould, when in its tilted position, can be rolled along the rail 15 of the tilting table and onto a mould curing rack 17 (Figure 7). The tilting table is on castors so that it can be lined up with the curing racks. This enables the moulds to be stored as they are being cured and the tilting table to be used for the next mould.

Once the resin has completed the first stage of curing, the mould is returned to the tilting table. The table is returned back to horizontal and the top of the mould is removed with the assistance of the drum lifter. The mould is then returned to the tilted position (Figure 8), where the article 6 is removed and stored flat to be allowed to air cure for 24 hours (Figure 9). This also frees up both halves of the mould to be cleaned and reused. The top half of the mould has rollers (not shown) at both ends so that when it is lifted from the mould base it can be turned upside down for the mould face to be cleaned.

Once the articles 6 have completed the second stage of curing, they are stacked on racks 18 (Figure 9) placed into a post curing oven 19 (Figure 10) to ensure the end product is fully cured prior to use, and is relieved of any stresses. Although the invention has been described with reference to a preferred embodiment it should be appreciated that it could be embodied in other forms. For instance, the use of special casting heads may enable many different effects to be produced in the material. The apparatus may be expanded to have two conveyer tilting tables with a continuous conveyer line that is capable of mass production casting; limited only by the number of moulds in operation.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. An apparatus for the production of a solid surface material article, comprising a mould and a production platform for supporting the mould during movement of the mould between spaced apart locations during a moulding process, the mould comprises upper and lower parts which, when held together define a cavity having the shape of the article, the production platform, in a first orientation support in the lower part of the mould to receive a flowable settable solid surface material and in a second orientation, providing support for the mould when inclined after the parts are joined, means for evacuating gases from the interior of the closed mould when in the inclined orientation.

2. An apparatus as claimed in claim 1 wherein the mould is fitted with a plurality of wheels or rollers along an edge.

3. An apparatus as claimed in claim 1 or 2 wherein the production platform comprises a roller bed for horizontally supporting the mould and facilitating horizontal movement of the mould.

4. An apparatus as claimed in any one of the preceding claims wherein at least a part of the production platform is tiltable between horizontal and inclined positions which define the first and second orientations.

5. An apparatus as claimed in any one of the preceding claims wherein the means for evacuating gases comprises a vacuum port in the upper part of the mould.

6. An apparatus as claimed in claim 5 wherein the vacuum port is adjacent the uppermost edge of the mould when inclined.

7. A method of forming an article of solid surface material comprising pouring a fluid settable mixture of the material into a horizontally oriented mould to at least partially fill the mould, closing the mould then inclining the closed mould, applying a partial vacuum to the interior of the closed mould while in the inclined position, curing the mixture in the closed mould to a stage where the moulded article can be removed from the mould for further processing.

8. A method of forming an article of solid surface material comprising: preparing a liquid resin mixture; placing the lower part of a mould on a production platform; pouring a measured volume of the prepared liquid resin mixture into the lower part of the mould; closing the mould by placing an upper part over the lower part to define a cavity within the mould containing the mixture, the cavity having the shape of the article with the exception of one free edge, and the total volume of the cavity being greater than the volume of the mixture; tilting the closed mould to cause the mixture to flow under the influence of gravity and leave an air space above it; evacuating the air space; and curing the mixture to form the article.

9. A method as claimed in claim 7 or 8 when using the apparatus of any one of claims 1-6.