The present invention concerns panels or sheets for the building industry and in particular panels or sheets for roofing provided with a seal device.

BACKGROUND TO THE INVENTION

In civil and industrial building, one of the methods of constructing roofs is to use double glass panels or transparent or opaque sheets made of thermoplastic material. In the latter case, panels made of honeycomb or compact polycarbonate, methacrylate, PVC etc. are typically used.

The use of said panels made of thermoplastic material in the building industry is particularly common for roofing greenhouses, industrial premises and large working areas where a metal supporting structure is combined with a roof made of different interconnected modular panels or sheets which combine a high resistance to atmospheric agents with the lightweight characteristics typical of these materials. To guarantee resistance to atmospheric agents, in particular rain, the method of connecting said panels or sheets during construction of the roof is very important. As it is known, the sheets used are normally closed and/or sealed on the edge sections by means of a post-extrusion process in order to avoid possible lateral infiltrations.

While building a roof with said modular sheets made of thermoplastic material, once the metal supporting structure is ready, they are put in place in such a way to obtain a continuous roofing surface.

The continuity of the roof is typically achieved by overlapping the sheets, in particular by overlapping the edge or rather the end portion of one sheet on another, as occurs in the case of roof tiles.

The sheets generally have a flat, corrugated or fretted shape and, once overlapped on the edges or ends, they are connected by means of fastening elements such as pins or nails.

To guarantee resistance to atmospheric elements, the connection between the sheets is generally made by overlapping an extended portion of their ends with subsequent fastening by means of pins. However, in this case there is a considerable waste of ? material, the need to- calculate the extension of the portion to be overlapped in order to avoid infiltrations, and lengthy positioning procedures. Furthermore this method does not offer a very effective seal system.

Another connecting method used is that of overlapping the ends of the sheets, placing in-between a foamed type coloured material which is compressed to create a seal between the overlapped faces of the sheets when the connection pins are inserted and screw-tightened. In this case, in addition to the unsightly presence of a strip of coloured foamed sealing material, said foamed material has to be applied manually entailing further costs and lengthy positioning procedures.

From the above, it is evident that one of the main drawbacks of the known modular sheet roofing system is the connection between two successive modules, in particular the methods of overlapping the sheets in order to guarantee an effective seal against external agents. With the known systems, furthermore, skilled labour are required for correct positioning and correct assembly requires time, given the precision required for application of the seal.

The object of the present invention is to solve the above drawbacks and provide a modular sheet able to guarantee optimal connection of several modular sheets or panels which is easy and quick to assemble without the need for skilled labour.

A further object of the present invention is to reduce material costs and on-site assembly times.

A further object is to provide a production method for a modular sheet as identified above.

SUMMARY OF THE INVENTION

These and other objects, which will be illustrated more clearly in the following description together with the accompanying drawings, are achieved by the present invention according to claim 1.

According to an advantageous aspect, the sheet with the seal device according to the invention reduces the assembly times and costs of the various panels. According to a further advantageous aspect, the sheet with the seal device according to the invention allows non-specialist labour and a reduced number of workers to be used for installation.

According to a further advantageous aspect, the sheet with the seal device according to the invention is already in one single piece prior to assembly with other sheets.

According to a further advantageous aspect, the seal device according to the invention does not need to be assembled during positioning of the various modular sheets.

According to a characteristic of the invention, the seal device is co-extruded with the modular sheet and is transparent like the sheet itself.

According to a further characteristic of the invention, the seal device with which the sheet is provided is flexible to adapt to the surface with which it comes into contact. According to a further characteristic of the invention, the seal device combined with the modular sheet operates by compression or flattening.

According to a further characteristic of the invention, the seal device is positioned at the end of the modular sheet parallel to the overlapping direction of the sheets.

According to a further characteristic of the invention, the seal device comprises at least one elastically yielding tab.

According to a further characteristic of the invention, said sheet is made of plastic material such as polycarbonate PC (honeycomb or compact), polymethyl methacrylate PMMA, polyvinyl chloride PVC, polyethylene terephthalate PET, polyethylene terephthalate glycol PETG and said seal device is made of plastic material such as natural rubber, silicone rubber, styrene-butadiene-styrene SBS, ethylene-propylene- diene monomer EPDM, styrene-ethylene-butylene-styrene SEBS, thermoplastic polyurethane TPU, elastomerised polyester, polypropylene PP + ethylene-propylene- diene monomer EPDM, LD polyethylene, ethylene-vinyl acetate EVA, vinyl rubber, polyvinyl chloride PVC or aromatised polyester.

BRIEF DESCRIPTION OF THE FIGURES

Further characteristics and advantages of the present invention will become more evident from the following description, provided by way of non-limiting example with reference to the accompanying drawings, in which:

- Figure 1 is a transverse cross section of a sheet according to the invention provided with a seal device;

- Figure 2 is a transverse cross section of the sheet of Figure 1 showing two corrugated sheets during overlapping and the seal device in the projecting position;

- Figure 3 is a transverse cross section of the sheet of Figure 1 showing two corrugated sheets overlapped and the seal device compressed.

DISCLOSURE OF PREFERRED EMBODIMENTS

A preferred embodiment of the sheet, object of the present invention, is shown in Figure 1 and comprises at least one sheet 1 with corrugated elements O, ΟΙ,.,.Οη and at least one seal device 2. By corrugated element O, 01,... On it is meant the concave and convex portions which alternate in the sheet. For example the corrugated element O is the portion of sheet between points A and B as shown in Figure 1.

Said seal device 2 is preferably an element in the shape of a tab, projecting with respect to the sheet 1 and arranged continuously along at least one end of the sheet in the direction of overlapping with a possible further sheet, i.e. in the direction orthogonal to the transverse section of the corrugated elements of the sheet.

Said tab projects with respect to the sheet 1 and is inclined with respect to the same so that when said sheet 3 overlaps another sheet, the tab is compressed, guaranteeing a wide adhesion surface.

Figure 2 and Figure 3 show in further detail the overlapping phase of two sheets 1 and l a. The tab 2, positioned at the end E of the sheet 1 which will overlap the end Ea of the sheet la, projects with respect to the sheet 1 and is inclined with respect to the same. The length of the tab 2, indicated by L in Figures 2 and 3, is between approximately 1/2 and 1/5 of the radius of curvature of the corrugated element O, 01 , ... On of the sheet 1 , preferably it is 1 /3.

When the sheet 1 is overlapped on the sheet la, the tab 2 positioned at the end E of the sheet 1 is pressed against the end Ea of the sheet la, adhering to it perfectly since it is made of elastically yielding material. The two sheets 1 and la are connected by fastening means (not shown) such as pins which allow, by bringing together the two ends E and Ea, flattening of the tab 2 against the end Ea of the sheet la so that it operates by compression. The tab 2 is inclined with respect to the surface of the sheet 1 and when the sheet 1 is pressed against the sheet la, said tab 2 is compressed against the surface of the sheet la providing a seal throughout its extension, as illustrated in Figure 3. Furthermore, the presence of a tab as identified above guarantees an effective seal even in the case of differential movements between the sheets since, due to the extensive seal surface area provided by said tab, small movements are possible between the sheets without compromising the adhesion of said tab to the surface of the sheet which it overlaps. The tab, elastically yielding and initially inclined with respect to the sheet to which it is connected, when it is compressed against the second sheet during tightening of the fastening means, tends to return to the initial position guaranteeing an effective improved seal independently of the reciprocal position of the sheets.

In the roofing systems of known type, a fairly large portion of the sheets is overlapped so that, when the fastening means are tightened to lock the panels in position, the fact of having large portions of sheets overlapped together with the pressure exerted by said fastening means guarantees a sufficient seal. A variation of the known system described is the use of gaskets inserted between the two overlapped ends of the panels. The use of the gasket which is made to adhere to the sheet before overlapping it with another, in addition to involving additional costs, requires accurate application in order not to compromise the seal of the system.

Therefore in the systems with sheet of the known type mentioned previously, the ends of the sheets must be connected by overlapping at least one whole corrugated element of the sheet, with or without gasket, to guarantee a certain level of seal. Advantageously in the case of the sheet according to the invention, it is sufficient to overlap only a portion of corrugated element because the presence of the tab at the end of the sheet guarantees an excellent seal when the two sheets are overlapped, even if only for a limited portion, and locked against each other by fastening means. Said portion of sheet which is overlapped is between approximately 10% and 30% of the length of the corrugated element, preferably 20%.

Furthermore, the use of a sheet provided with seal device according to the invention saves time during installation. In fact, during assembly accurate control is not necessary when overlapping the end of one sheet onto the end of another since the seal device is continuous along the whole edge of the sheet and is effective even if the sheets are not perfectly aligned.

The sheet according to the invention is made of plastic material such as polycarbonate PC (honeycomb or compact), polymethyl methacrylate PMMA, polyvinyl chloride PVC, polyethylene terephthalate PET, polyethylene terephthalate glycol PETG, and is preferably made of PC or PMMA.

The seal device or tab has a profile which can be deformed by compression and is made of non-foamed plastic material such as natural rubber, silicone rubber, styrene- butadiene-styrene SBS, ethylene-propylene-diene monomer EPDM, styrene-ethylene- butylene-styrene SEBS, thermoplastic polyurethane TPU, elastomerised polyester, PP + EPDM, LD polyethylene, ethylene-vinyl acetate EVA, vinyl rubber, polyvinyl chloride PVC, aromatised polyester, preferably TPU or polyethylene.

However, a PVC seal device is not combined with a sheet made of polycarbonate PC. The sheet and the seal device are advantageously factory produced in order to obtain one single piece which is then installed without requiring further labour and use of other insulating materials to be glued or fastened.

The sheet according to the invention is advantageously produced by means of processes known in the art such as co-extrusion or post-extrusion or overmoulding. In the case of co-extrusion, the seal device is adhered to the sheet after the sheet comes out of the extrusion head and, being both the materials in co-extrusion in the melting phase when the surfaces come into contact with each other, the adhesion will result better than with post-extrusion.