DK150978B - PROCEDURE FOR CONTINUOUS PREPARATION OF A PLATE OF AT LEAST TWO LAYERS OF THERMOPLASTIC EXPANDED SUBSTANCES - Google Patents

Description

150978 i

The invention relates to a method for continuously producing a sheet of at least two layers of thermoplastic expanded plastic material as further specified in the preamble of the claim.

In the processing of expandable thermoplastic moldings, it is known by extrusion to obtain directly single-piece sheets of a predetermined and sometimes considerable thickness, depending on the purpose of the product. However, the known methods have only allowed the production of products with a relatively high density that cannot be underestimated. In practice, in these methods, it is always necessary to work at high temperatures and to subject the extruded, expanded plates some calibration operations 15 as well as cooling for long periods. In addition, the sheets made in this way must be appropriately stored at controlled temperature, which, given the relatively large volume of material, requires relatively large spaces and this entails high costs.

In the specification for German usage pattern No. 7100165, the manufacture of a composite film consisting of a reinforcing layer, e.g. a paper web, and some on both sides thereof adhered to foamed plastic layers, e.g. the polystyrene, which is brought to an expansion temperature below the melting temperature prior to the adhesive and thereby foamed.

This is about producing hard and strong sheets with relatively little cost. These plates are complex, inhomogeneous products of several different layers.

30 From the description to German publication no.

1504917 also discloses a bonding of foils by welding, although in a different context and for the manufacture of elastic floor or wall coverings.

In relation to this, the present invention relates to the manufacture of sheets of at least two layers of thermoplastic expanded plastics, the manufacture having to be simplified in such a way that when storing sheets of only a single thickness value, sheets of arbitrary thickness can be produced, all according to the practical requirements.

For this purpose, according to the invention, it is disclosed that it proceeds as indicated in the characterizing part of the claim.

Thereby, the advantage is obtained that, when working at relatively low temperatures, multi-layer sheets having a density less than the density of the individual foils used as starting material and less than the density obtained in the production of sheets of a single sheet can be produced. piece.

Robust, compact products are obtained, the manufacturing method is simplified, and the manufacturing costs are reduced. First and foremost, however, advantages are obtained with regard to the storage, which is simplified because only plates of a certain thickness must be stored, since the existing sheets can be joined to thicker sheets at any time as needed.

The invention will be explained in more detail in connection with the drawing, in which fig. 1 is a side view of an apparatus for carrying out the method according to the invention; FIG. 2 is a part of the embodiment of FIG. 1 is a side view of the apparatus shown in FIG. 25 and partly in section and on a larger scale; and FIG. 3 is a perspective view of a plate made by the method according to the invention.

In the drawing, an oven is shown to be used to simultaneously heat two or more sheets 2 of expanded thermoplastic material to be joined, a calibration and cooling station 3 for the sheets in unified state, and a station 4 used for the subsequent printing and cutting of the product into sheets.

The furnace 1 comprises a chamber 5 in which support and transport means are provided for each sheet, the transport means permitting each sheet 2 to move continuously through the furnace. These means of transport can e.g. be in the form of rollers 6 which determine a path for the sheets. Alternatively, the means of transport may be endless belts or chains or any other suitable means capable of individually and separately transporting the sheets 2, the supporting and means of transport 6 being aligned with corresponding inlet passage 7 in one wall of the furnace 1, the sheets 2 is extruded and matured and then wound around rollers R, sheets are pulled from rollers R and enter furnace 1 through passages 7, as shown, these passages 7 are formed in one of the end walls of furnace 1,

However, it should be noted that the sheets of expanded material can be applied either horizontally or vertically without any detrimental effect on the processing thereof, therefore the earring members 6 for the sheets are mounted accordingly.

In all cases, in the wall of the furnace opposite the wall with the inlet passages 7, a single outlet passage 8 is provided for all the sheets 2. In the furnace 1 near the outlet passage 8, at least one pair of adjustable guide rollers 9, 20 are arranged which cause the sheets 2 to converge towards each other. so that they are completely overlaid.

For heating the sheets of extruded expanded material 2 as they pass through the furnace 1, heating means 10 such as electrical resistance sweep heating panels are arranged between the support and the transport means 6 for the sheets 2, which heating panels maintain a furnace chamber at a predetermined temperature to producing a predetermined expansion of each sheet. It will be readily appreciated that the expansion of each sheet causes a reduction in its density.

Further, in the region near the outlet 8 of the furnace 1, where the sheets 2 'converge against the pair of guide rollers 9, additional heating elements 11 are provided for heating opposite surface areas of neighboring sheets to their melting temperature. Such melting allows the neighboring sheets to adhere or fuse as they pass between the rollers 9.

4 150978

This applies whether the surfaces of the sheets are slippery or have been subjected to prior mechanical pretreatment.

Thus, during their passage through the furnace 1, the sheets 2 can be treated at any suitable desired temperature for a predetermined period of time. In such a treatment, they undergo an expansion beyond that at the beginning, which makes it possible to reduce the density of the sheet to a desired value. Following the further expansion, the surfaces adhere as they are subjected to the action of the heating elements 11 so that at least their surface area is heated to their melting point. Thus, as they pass between the guide rollers 9, the sheets are welded together to form a single plate 20 with a large number of layers corresponding to the number of sheets 15 used, the thickness of the sheet being equal to the sum of the thicknesses of the sheets used, and a density. which depends on the weight range of the sheets used.

Depending on the nature of the thermoplastic material from which the sheets are formed, the temperature of the furnace 20 can vary from 100 to 200 ° C, and the rate at which the sheets are transported through the furnace can be from 4 to 15 m. Using these parameters is it is possible to achieve a reduction in density from 60 to 70 g / liter in the starting sheets to 22 g / liter in the final product.

In other words, the method according to the invention allows the volume of the starting sheet to be significantly increased without causing any significant technical difficulties.

The multilayer product thus produced can then be passed to and through a calibration and cooling station 5, 30 where the physical properties of the final product are fixed. This station 3 comprises, as shown in Fig. 2, two sets of adjustable rollers 12 facing each other so that a guide path is determined between them along which the plate 20 is to pass. During its passage between the rollers, the sheet is cooled, e.g.

35 of air flowing out through orifices 13 disposed above and below the rollers 12, and of water.

5 150978

After cooling, the product is prepared to undergo subsequent printing and to be cut to the desired size. This is done in the treatment station 4.

Using the above-described method, it is possible to form sheets from any extruded expanded thermoplastic material, the sheets constituting the plate optionally containing such additives as flame retardant and coloring agents. If the sheets are of fibrous material, the fibers may have an orientation or be randomly distributed.

During the process, it is also possible to apply one or both surfaces of the finished product to plastic laminates or plain or bituminous paper to obtain a final product with a desired structure and with desired properties.

Finally, in a simple and economical manner, a multilayer product having a density, heat insulation, mechanical strength, low moisture absorption, high water vapor permeability and dimensional stability similar to similar products is obtained directly by extrusion as a single layer structure.

Claims (1)

A method of continuously producing a sheet of at least two layers of thermoplastic expanded plastic, wherein foil of expanded plastic in a heating zone is heated to an expansion temperature less than the melting temperature but high enough to expand the plastic to a predetermined final value for the material weight filling and connected to each other, characterized in that the films in a first heating zone are separately heated separately to the expansion temperature, the 10 surfaces of the films to be connected to each other are heated to melt temperature in a second heating zone, and that the surfaces heated by melting are then welded together by pressing against each other.