CH635776A5 - PROCEDURE FOR THE COUPLING OF EXPANDED THERMOPLASTIC RESIN LEAVES, AND COMPOSITE PANEL OBTAINED BY THAT PROCEDURE. - Google Patents

Description

The present invention is directed to a process for coupling several sheets of expanded thermoplastic resin to form multi-layered panels. The invention is also directed to a composite panel obtained by said process and to an apparatus for its practical realization.

In the field of the processing of expandable thermoplastic resins, the technique of obtaining slabs or panels in a single body and with predetermined thicknesses, also significant, according to the intended use of the product, is known. However, the method heretofore allows to obtain products only with relatively high densities below which it is not possible to go. In practice then, with this method it is always necessary to operate at rather high temperatures and to subject the extruded expanded panels to calibration operations and to a long cooling period. The panels thus produced also require adequate seasoning at controlled temperature which, considering the bulkiness of the material, entails the availability of large chambers with a consequent significant impact both on the operating costs of the plants and on the production costs of the desired material .

On the other hand, it is an object of the present invention to provide a process and an apparatus which allow the production of panels in expanded thermoplastic material starting from leaves or sheets of the same material extruded previously and already cured.

From this derives the advantage of being able to obtain, operating at relatively low temperatures, multi-layer panels with a density lower than that of the single leaves or starting plates and reduced compared to that achievable with the production of panels in a single body. It also eliminates the need for seasoning of the resulting panels with consequent reduction of time and reduction of production costs.

The process for the coupling of two or more sheets of thermoplastic resin foam previously extruded with a predetermined density and subjected to seasoning involves the separate conduction and controlled speed of said sheets of thermoplastic resin expanded through a heating oven at controlled temperature to determine a additional expansion of said leaves up to a predetermined density, overheating up to the melting temperature of the surfaces of said leaves opposite each other near the exit of said oven, a forced approach of said leaves until they are tightly coupled by overlapping and welding of said superheated surfaces, and the exit from said oven of said coupled and welded leaves for the conduction of the composite panel resulting in a calibration and cooling station and subsequently in a longitudinal and / or transversal cutting station of said panel .

The present invention will in any case be described in more detail in the following description

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reference to the attached indicative and non-limiting drawing in which:

fig. 1 shows a diagram of an apparatus for carrying out the method;

fig. 2 shows a part of the apparatus in section, and fig. 3 shows a sectional view of the resulting composite panel.

In said drawing 1 generally indicates an oven for the simultaneous heating of two or more leaves 2 of expanded thermoplastic material to be coupled, while 3 indicates the calibration and cooling station of the leaves once coupled and 4 the station for any cutting printing in product panels.

The heating oven comprises a chamber 5 in which there are mounted support and conduction means, with continuous movement, of each single leaf 2 to be coupled with the others, said means being able to consist of roller ways 6 as represented e.g. in fig. 2, or by endless belt, chain, grid conveyors and other suitable devices with which the leaves 2 are moved individually and separately.

Said support and driving means 6 are aligned with corresponding passages 7 for entering the oven 1 of the leaves 2 coming, in the direction of the arrows F, from rolls R - v. Fig. 1 - in which they had been wrapped during their extrusion and during the seasoning.

It should be noted that the foams of foamed material can be fed continuously so as to be oriented, in the sense of their width, horizontally or vertically without altering the treatment conditions and that therefore the conduction means 6 of said foils will be mounted accordingly.

In any case, the oven 1 has, on the opposite side to the inlet passages 7, a single forced and concurrent outlet passage 8 of all the leaves 2, at least a pair of guide rollers being mounted near said outlet passage 8 9, at an adjustable distance, suitable for making the leaves converge and put together for close superposition.

For heating, according to the process, the extruded leaves 2 while they pass through the oven

I, heat generating means 10 are provided, e.g. suitably powered electric resistance panels, arranged between the support and conduction means 6 of said leaves 2 and such as to maintain a controlled temperature in the oven chamber to determine a predetermined expansion of each individual leaf and correspondingly a reduction to the desired value of the density of the constituent material.

In addition, further heating elements are arranged adjacent the exit 8 from the oven 1, between the zones 2 'of the leaves converging towards the pair of guide rollers 9

II, able to bring the opposite surfaces of said zones 2 'to the melting temperature so as to allow then the adhesion by mutual welding of said leaves, also independently of the structure of said surfaces, which can be smooth or mechanically pre-treated.

635776

Basically, according to the process, during their translation through the oven 1 the leaves 2, due to the effect of heat and in relation to the exposure time thereto, undergo an additional expansion to the starting one thus reducing their density to the desired value ( e.g. from 22 g / l.). After the additional expansion, the surfaces destined to adhere are overheated by the heated elements 11 up to the melting temperature so that the leaves, when engaged by the guide rollers 9, are welded together forming a continuous panel 20 with a number of layers corresponding to the number of leaves coupled and welded together with a thickness equal to the sum of the thicknesses of said leaves and with a density equal to that of each leaf treated in the oven.

Depending on the thermoplastic material expanded in leaves treated from time to time, the oven temperature can vary from 100 ° C to 200 ° C, as well as varying from 4 to 15 or more meters the speed of conduction of the leaves through the oven will be possible obtain, within these temperatures, a reduction in density from 60-70 gr / lit. of the starting leaves at 22 gr / lit. of the finished product or not.

In other words, the volume of the starting leaves can be increased substantially and without technical difficulties.

The multilayer panel exiting the oven is then led through the calibration and cooling station 3 intended to fix the final characteristics of the product. Said station 3 comprises, in the schematic embodiment shown in fig. 2, two pluralities of opposed rollers 12-12 with adjustable distance constituting an obligatory conduction path of the panel 20 for its calibration while it is being cooled e.g. air operated by means of vents 13 arranged above and below said rollers.

After its cooling, the product is immediately ready for any printing operations as well as for the longitudinal and / or transversal cutting in the station 4 to form elements of predetermined dimensions according to the destination.

With the described method it is possible to couple by overlapping and welding together the leaves of any extruded thermoplastic foam material, containing or not fillers, various additives, self-extinguishing products, and dyes, said leaves, also having different orientations of the relative fibers.

During this process it will also be possible to provide for the application, on one or both of the external surfaces of the product, of plastic laminates or of plain or bituminous paper so as to obtain at the end a product with the desired structure and characteristics.

Ultimately, a multi-layered product is obtained simply and economically, both as a plant and as a process - see Fig. 3 - with density properties, insulating power, mechanical resistance, no water absorption, high resistance to the diffusion of water vapor and dimensional stability perfectly comparable to those of similar products obtained directly by extrusion in a single body and therefore lends itself to the most varied uses.

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1 sheet of drawings

Claims (11)

635776 (1) at controlled temperature to determine an additional expansion of said leaves up to a predetermined density, overheating (11) up to the melting temperature of the surfaces of said leaves opposed to each other near the exit from said oven, an approach forced (9) of said leaves until their tight coupling by superimposition and welding of said superheated surfaces, and the exit from said oven of said coupled and welded leaves for the conduction of the resulting composite panel (20) in a calibration station ( 3) and cooling and thereafter in a longitudinal and / or transversal cutting station (4) of said panel. 1. Procedure for the coupling of two or more leaves of expanded thermoplastic resin previously extruded with a predetermined density and subjected to seasoning, characterized in that it provides for the separate and controlled speed conduction of said leaves (2) of thermoplastic resin expanded through a heating oven (2), of the first heat generating means (10) to maintain a controlled temperature in the oven so that the leaves undergo an additional expansion up to the predetermined density, of the guide means (9) to make said leaves converge and bring each other close to their close overlapping of the second heating means (11) adapted to heat the opposite surfaces of said leaves up to a melting temperature before the overlapping and adhesion of the leaves themselves between said guide means to form a composite panel, of the calibration and cooling means (12-13) of the panel after its exit from the oven and of the longitudinal and / or transverse cutting means (4) of the panel itself. 2. Process according to claim 1, characterized in that it provides for coupling by overlapping and welding of leaves with parallel oriented fibers. 2 3. Process according to claim 1, characterized in that it provides for coupling by overlapping and welding of leaves with fibers oriented differently. 4. Process according to claims 2 or 3, further characterized in that it provides for the coupling of said leaves with plastic laminates, plain or bituminous paper directly during the treatment. 5. Extruded expanded thermoplastic resin panel obtained with the process according to claim 1, characterized by a body consisting of several expanded leaves (2), superimposed and welded to each other to form as many layers, each with a greater thickness and a density less than the thickness and density of the starting leaves respectively. Apparatus for carrying out the method according to claim 1, comprising a heating furnace (1) with a chamber (5) having on one side a plurality of separate inlet passages of as many leaves (2) of extruded thermoplastic foam material and on the opposite side a single product exit passage (8), the continuous support and conduction means (6) provided in said oven for the separate translation into said leaves 7. Apparatus according to claim 6, wherein said continuous support and driving means (6) consist of roller ways or endless conveyor belts or chains. 8. Apparatus according to claim 6, wherein said guide means (9) are constituted by a pair of adjustable rollers arranged in proximity of the exit passage (8) of the oven. 9. Apparatus according to claim 6, wherein said heat generating means are powered electrically or with a fuel. 10. Apparatus according to claim 6, wherein said calibration means are constituted by two plurality of superimposed rollers (12-12) delimiting in combination an obligatory passage way of the product. 11. Apparatus according to claims 6 and 10, wherein said cooling means consist of air diffusion vents arranged above and below the two pluralities of rollers (12-12).