The present invention relates to a bitumen-polymer membrane.

The present invention relates also to a base for providing said bitumen-polymer membrane.

Bitumen-polymer sheaths, adapted to protect structures from rainwater and other water, are currently known and widely used in the building sector.

These bitumen-polymer sheaths are generally constituted by a reinforcement impregnated with a compound which comprises bitumen, polymeric resins and so-called "fillers"; the bitumen, the polymeric resins and the fillers are conveniently mixed in the appropriate proportions at a temperature of approximately 200°C so as to form a viscous compound, which is fundamental for the production of bitumen-polymer sheaths or membranes owing to its excellent impermeableness.

The reinforcement is designed for several functions and first of all is indispensable for the production process of the bitumen-polymer sheath and is adapted to offer the impermeable compound its own mechanical and physical characteristics, which the compound does not have.

The reinforcement is usually constituted by a glass fiber sheet or by a nonwoven polyester fabric, wherein the latter covers substantially the entire market of the bitumen-polymer sheets.

Bitumen-polymer sheets of the known type, despite being widespread and appreciated, have limitations that the known technology has not been able to solve.

A first aspect is constituted by the limits of impregnability of the nonwoven polyester fabric: when a design for use of such a sheath of the known type entails higher mechanical strengths than ordinary applications, it is actually impossible to use sheaths with sheets of polyester of over 300 grams per square meter, since this polyester sheet is so dense that it renders impregnation on the part of the compound difficult if not impossible. Sheaths with a polyester sheet of 120 grams per square meter are usually used and cannot provide mechanical properties that are sufficient for a use that provides for mechanical strengths that exceed those of ordinary applications.

Another drawback of bitumen-polymer sheaths with polyester sheet reinforcement is constituted by the fact that at the experimental level it has been shown that in a sheath of the known type that is subjected to traction the polyester sheet inside it and the entire sheath elongates exceptionally and equally exceptionally is deformed transversely, tapering increasingly toward the central region.

A further drawback of bitumen-polymer sheets of the known type is constituted by the fact that the polyester sheet is dimensionally unstable with respect to temperature variations.

This dimensional instability entails variations that affect and stress severely the entire perimeter of the the bitumen-polymer membrane, and to be certain of tightness it is necessary to oversize the overlaps, generating excessive waste during installation.

The dimensional variations of the finished bitumen-polymer sheath are therefore due to the dimensional instabilities of the reinforcement made of nonwoven polyester fabric and the risk of deformations due to dimensional instability in fact forces as a precaution, during installation, overlaps of joining flaps which are up to 10 centimeters wide laterally and up to 30 centimeters wide at the ends in a longitudinal direction, whereas a technical overlap of two or three centimeters both laterally and at the ends might be sufficient for a stable sheath.

Furthermore, bitumen-polymer sheaths of the known type also have other limitations which relate to mechanical behaviors, such as poor resistance to tearing and aggression of rodents, as well as a limited aptness for mechanical fixing by means of nails, rivets, screws and the like.

Currently, composite reinforcements are known which comprise polyester sheets coupled with glass fibers, which are capable of reducing the problem caused by dimensional instability but not of solving it.

The aim of the present invention is to provide a bitumen-polymer membrane that is capable of obviating the cited limitations of sheaths and membranes of the known type.

Within this aim, an object of the invention is to provide a bitumen- polymer membrane that has better mechanical properties than sheaths of the known type.

Another object of the invention is therefore to provide a bitumen- polymer sheath that has higher dimensional stability than sheaths of the known type.

A further object of the invention is to provide a bitumen-polymer membrane the sheets of which, during installation, can be superimposed with great saving of material with respect to currently known sheaths.

Another object of the invention is to provide a bitumen-polymer membrane the integrity of which, once installed, lasts longer than sheaths of the known type.

Another object of the invention is to provide a bitumen-polymer membrane that is simple to use like sheaths of the known type and is indeed better suited for mechanical fixing.

Another object of the invention is to provide a base that is adapted to be integrated in a bitumen-polymer membrane according to the same invention.

A still further object of the present invention is to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

This aim and these and other objects which will become better apparent hereinafter, are achieved by a bitumen-polymer membrane according to claim 1 , optionally provided with one or more of the characteristics of the dependent claims. Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the bitumen-polymer membrane according to the invention, illustrated by way of nonlimiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view of a bitumen-polymer membrane according to the invention;

Figure 2 is an exploded perspective view of a base comprised in the bitumen-polymer membrane according to the invention;

Figure 3 is a schematic view of a portion of a lateral cross-section of a base comprised in the bitumen-polymer membrane according to the invention;

Figure 4 is a perspective view of a bitumen-polymer membrane according to the invention in a constructive variation thereof;

Figure 5 is an exploded perspective view of a base comprised in the bitumen-polymer membrane according to the invention in the variation of Figure 4.

With reference to the cited figures, a bitumen-polymer membrane according to the invention is designated generally by the reference numeral 10.

Such bitumen-polymer membrane 10 comprises a base 1 1 that is immersed in a compound of bitumen, polymeric resins and fillers 12 and is surrounded by said compound 12.

The base 11 comprises a structural mesh 13, which is coupled to a flexible element made of impregnable material 14 arranged so as to affect the structural mesh 13.

The flexible element made of impregnable material 14 is interposed between a first series 15 of first filaments 16 of said structural mesh 13, which are parallel and extended in a first direction X, and a second series 17 of second metallic filaments 18 of the same structural mesh 13, which are parallel and are extended in a second direction Y which is transverse to said first direction X.

The first filaments 16 of the first series 15 are fixed to the second filaments 18 of the second series 17 in multiple points 20.

In the present constructive example, which does not limit the invention, the flexible element 14 has an array of through holes 19, at each of which a first filament 16 of the first series 15 is fixed to a second filament 18 of the second series 17.

In the present constructive example, the first filaments 16 and the second filaments 18 are made of metallic material.

The first filaments 16 are fixed to the second filaments 18 by welding, for example by electric welding.

The welding between the first filaments 16 and the second filaments 18 is to be understood as being of a per se known type.

The structural mesh 13 is therefore constituted by an electro welded metallic mesh.

The structural mesh 13 provides the necessary mechanical and physical characteristics, while the element made of impregnable material 14 gives shape and substance to the finished product by retaining the compound.

The flexible element made of impregnable material is constituted by a sheet made of fabric or nonwoven fabric or by a sheet made of another impregnable material, exampled by a sheet made of polyester, or glass fiber or paper material or other similar and equivalent materials.

In a constructive variation of the invention, not shown for the sake of simplicity, the base 11 comprises multiple superimposed flexible elements, at least one of which is impregnable.

The filaments 16 and 18, made of metallic material, are constituted for example by wires made of iron or low-alloy carbon steel or stainless steel or another metallic material configured to allow the joining of the wires mechanically or chemically.

In the present constructive example, the directions X and Y of the first filaments 16 and of the second filaments 18 are mutually perpendicular.

It is to be understood that the present invention also relates to embodiments in which the directions X and Y are transverse to each other at angles that are greater than or smaller than 90°.

In a constructive variation of the membrane 110 shown schematically in Figures 4 and 5, the impregnable flexible element 114 is continuous and is configured to allow the passage of electric current by electric permeability or conductivity; by virtue of this particularity, the flexible element 114 allows the electric welding of the first filaments 16 with the second filaments 18 even in the absence of an array of through holes.

In a further constructive variation, the structural mesh 13 is constituted by first filaments 16 and second filaments 18 made of plastic material.

The first filaments 16 and the second filaments 18 made of plastic material can be likewise welded to each other.

The present invention also relates to a base 11 for providing a bitumen-polymer membrane as described above.

The base 11 comprises an electrically welded mesh 13, coupled to at least one flexible element made of impregnable material 14 that is arranged so as to affect the metallic mesh 13, and is characterized in that said at least one flexible element made of impregnable material 14 is interposed between a first series 15 of first metallic filaments 16, which are parallel and extended in a first direction X, and a second series 17 of second metallic filaments 18, which are parallel and extended in a second direction Y that is transverse to said first direction X, said flexible element 14 having an array of through holes 19 at each of which a first metallic filament 16 of the first series 15 is welded to a second metallic filament 18 of the second series 17.

In practice it has been found that the invention achieves the intended aim and objects.

In particular, the invention provides a bitumen-polymer membrane the base of which has compound retention properties that are not inferior, if not better than known bitumen-polymer sheaths, by virtue of the presence of the sheets of impregnable material, and at the same time has better mechanical properties than sheaths of the known type, by virtue of the presence of the electrically welded metallic mesh.

Therefore, the invention has provided a membrane that has a greater dimensional stability than sheaths of the known type, in particular is dimensionally stable with respect to variations of the temperatures caused by the alternation of each season; specific laboratory tests have demonstrated dimensional variations of 0.1÷0.2% in glass fiber, 0.2÷0.4% in polyester and no variation in all the various samples of the invention as described above in its various embodiments.

Accordingly, the invention has provided a bitumen-polymer membrane the sheets of which, during installation, can be superimposed with a great saving of material with respect to currently known sheaths.

Moreover, the invention has provided a bitumen-polymer membrane the integrity of which, once installed, lasts longer than sheaths of the known type.

Furthermore, the invention has provided a bitumen-polymer membrane that is simple to use, like sheaths of the known type, and is more suitable for mechanical fixing with nails, rivets, screws and other similar means.

Not least, the invention provides a base for a bitumen-polymer membrane that is far more stable dimensionally than known reinforcements and is capable of maintaining the shape of the membrane dimensionally unchanged with respect to temperature variations.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.

In practice, the components and materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. 102016000129200 (UA2016A009283) from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.