SE506046C2 - Process for making relief patterned disc-shaped articles - Google Patents

Abstract

Sheet-like products comprising a fibrous material, such as sawdust, wood chippings or wood powder, and a thermoplastic glue can be provided with a relief pattern by compression moulding the products in a pressure-cell press.

Description

15 20 25 30 506 046 areas of the surface made of different materials. In addition, the technique is not suitable for the production of disc-shaped articles with patterns in the form of depressions in the surface.

EP 0 574 953 deals with a method for ställning setting up relay ön patterned wood composite boards where the boards can be formed simultaneously with olika your different patterns. The stated pressing time (about 5 minutes) is quite long, which leads to relatively high manufacturing costs. Furthermore, the patterned boards have a fairly small area (20 x 20 inches).

There is thus a need for alternative methods for producing embossed disc-shaped discs which solve the above-mentioned problems, and with the aid of which it is possible to press discs with an area of at least 1.5 - 2 m2.

SUMMARY OF THE INVENTION It has now been found that by compression molding a pre-made disc containing a mixture of material breast material and thermoplastic adhesive a pressure cell type press, one can quickly and easily produce relief patterned disc-shaped articles of good quality.

The invention will now be described with the aid of the following figures, of which Figure 1 shows an example of a disc pattern which can be produced with this invention; Figure 2 shows a cross section through the patterned board in Figure 2.

Detailed description of the process By using a pressure cell type press, it is possible to obtain properties which cannot be obtained with a conventional piston type press. In a pressure cell press, the pressure is transmitted by an elastic membrane. The press blank is then pressed in many directions simultaneously, which makes it possible for the blank to be quickly and easily formed according to the shape of an underlying tool. As a result, the articles that are molded can be provided with very complicated patterns. For suitable pressing blanks, the pressing can also be carried out with a very high pressure, above 800 bar, preferably above 50 bar, which makes the pressing time very short, less 2 minutes, preferably less than 1 min.

SE-C-452 436 discloses a pressure cell type press plant which is well suited for use in connection with the process for producing embossed disc-shaped disc-shaped articles according to this invention. This press is designed to manufacture hard-to-form sheet metal details. A hard forming tool is placed in the bottom of a trough, after which the pressure sieve is placed over said tool. The trough is pushed into the press as the blank is pressed against the forming tool with an elastic diaphragm that can be hydraulically actuated.

If a disc of a fi chest material, such as a chipboard, which does not contain any thermoplastic adhesive, is compression molded at high pressure using a pressure cell type press and a hard forming tool, the disc will crack. Because thermoplastic adhesives are cold surfaces, these problems do not arise as easily when a sheet of breast material containing such adhesive is compression molded. The pressing properties of such a board can also be improved by heating. A person skilled in the art can easily test suitable pressing temperatures for different types of glue.

In addition, according to the invention, the formability of the brittle disc can be further increased if the disc is heated to a temperature of 40 - 70 ° C, preferably 45 - 60 ° C before pressing.

This heating can advantageously take place in a microwave oven.

Preferably, the brittle material is a wood-based material such as sawdust, wood ice or wood powder etc. Suitable thermoplastic adhesives consist of polymers, for example EVA (ethylene-vinyl acetate copolymer), ethylene-acrylate copolymer and PVAC (polyvinyl acetate) as well as other olefin adhesives, etc. manufacture of particle board, board, etc.

The invention will now be described with the aid of the following exemplary embodiments. The examples are attached for illustrative purposes and are not intended to limit the scope of the invention. 506 046 Example A chipboard whose adhesive component consists of the thermoplastic polymer EVA was first lightly heated to 60 ° C in a microwave oven, and then pressed in a pressure cell press obtained from ABB, Västerås. When pressing, the chipboard was placed on a forming tool with the desired pattern. The forming tool was heated to 80 ° C and then the chipboard was pressed for 1 minute at a pressure of 1000 bar. A chipboard with an excellent relief pattern was obtained.

Claims (8)

10 15 20 25 506 04-6 Patent claims Process for the production of embossed articles, characterized in that an article made from a mixture of fi breast material and tinplastic glue is die-pressed in a pressure cell type press. Method according to claim 1, characterized in that the article is disc-shaped. Method according to one of Claims 1 or 2, characterized in that the brittle material is a wood-based material, such as sawdust, wood powder and wood ice. Process according to one of the preceding claims, characterized in that the thermoplastic adhesive is EVA, ethylene-acrylate copolymer, PVAC or olefin adhesive. Method according to one of the preceding claims, characterized in that the disc-shaped article is heated to 40-70 ° C, preferably 45-60 ° C, before the actual pressing. Method according to one of the preceding claims, characterized in that the forming tool has an elevated temperature during pressing. Process according to Claim 6, characterized in that the temperature is kept in the range from 30 to 160 ° C, preferably from 50 to 10 ° C. Method according to one of the preceding claims, characterized in that the press pressure is kept above 800 bar, preferably above 1000 bar.