DESCRIPTION

Technical field

The present invention relates to a material for coating waterproofing surfaces and to a method of coating waterproofing surfaces.

Prior art

In building industry, surface waterproofing of coverings, such as building roofs or the like, is at present obtained by means of bituminous membranes, PVC, PP, possibly associated with metal sheets (smooth or corrugated or otherwise worked, for instance with right-angle corrugation) or with sheets of plastic or vitreous material, glass (for instance rooflights, portholes, glazing units), just to mention some examples.

Such coatings, and in particular the bituminous coating material, generally have an aesthetically unpleasant exposed face of a single-colour.

Those characteristics limit therefore the use of such materials in situations where the aesthetic appearance, and especially the colour, cannot be neglected, since for instance a particular architectonic rule is to be met.

Therefore, bituminous membranes having an external surface that can be coloured/and or printed during manufacture, in order to give the exposed surface a pleasant aesthetic appearance, or in any case an appearance suitable for insertion in specific architectural contexts, have been developed in the past.

Document IT- 1301739 discloses for instance a layered sheet material for waterproofing, comprising a layer of coating material, a layer consisting of a bituminous sheath and an intermediate layer of a material capable of promoting the coupling between said layer of coating material and said bituminous sheath. The layer of coating material may consist of a plastic material or a textile material, with the possible addition of coloured pigments in order to give the desired colour to the product.

Yet, there is the need in the field to give suitable aesthetic and/or reflectance properties to already existing waterproofing surfaces, i.e. surfaces already laid and in use but lacking such properties or having lost them due to wear and time. Such a need is at present met by replacing the waterproofing material with another material having the suitable aesthetic appearance.

Such a replacement is however laborious and, above all, expensive and often not justified, especially when the material to be removed still has good waterproofing properties.

There is also the need to give the same adequate aesthetic properties, even before laying, to materials, e.g. bituminous sheaths, that are at present commercially available and lack such properties. The problem of how to give suitable aesthetic and/or reflectance properties to the already existing waterproofing surfaces, while possibly causing at the same time also an improvement in the waterproofing properties of the material, is at present empirically solved, for instance by using varnishes or the like, which are spread over the exposed face of the surfaces the appearance of which is to be improved.

Thus, it is the main object of the invention to solve the above mentioned problem by providing a material for coating waterproofing surfaces, which allows imparting adequate reflectance properties and possibly a pleasant appearance to the exposed face of such surfaces and which has high resistance to atmospheric agents, once it has been applied.

It is another object of the invention to provide a material of the above kind, which is cheap to be obtained so that it can be industrially produced at advantageous costs.

It is a further object of the invention to provide a method of coating waterproofing surfaces, which allows imparting the desired properties, for instance reflectance properties, anti-smog properties and so on, and the desired aesthetic appearance to the material for coating waterproofing surfaces.

Description of the invention

The invention achieves these objects by means of a bituminous membrane and a method as claimed in the appended claims.

Further advantageous features of the invention are the subject matter of the dependent claims.

Thanks to the coating material according to the invention, it is advantageously possible to obtain waterproof surfaces which high aesthetic properties, without negatively affecting the waterproofing properties of the underlying membrane.

Brief Description of the Drawings

Some preferred embodiments of the invention will be given by way of non limiting examples with reference to the accompanying drawings, in which:

- Fig. 1 shows a first embodiment of the material;

- Fig. 2 shows a second embodiment of the material;

- Fig. 3 shows a third embodiment of the material;

- Fig. 4 shows a schematic representation of a plant for producing the material. Description of some preferred embodiments

Referring to Fig. 1, the coating material according to a first embodiment of the invention consists of layered sheet material, comprising a support layer 11 of synthetic and/or textile material, and a layer 12, including a modified acrylic resin with high reflectance, preferably white and having a weight up to 1000 g/m ² .

Advantageously, according to the invention, the acrylic resin employed includes an aqueous dispersion of inorganic charges, titanium dioxide, calcium carbonate, talc, hollow glass microspheres, in an acrylic styrene resin. Such a composition for the resin of layer 12 has proved particularly effective in order to obtain the desired results of reflectance and duration.

Moreover, an acrylic resin that is also possibly suitable for the purpose is commercially available in Italy under the trade name Biank.

In both cases, the resins are white paste resins, with the addition of polymers, and they can be spread over layer 11 and dried. Always according to the invention, substances of various kinds, for instance pigments for imparting a particular colour, quartz, vitreous material, anti-flame substances, anti-smog substances with photocatalytic properties, can further be added to said acrylic resin forming layer 12, depending on whether it is desired to improve the reflectance properties or the structural strength properties or other properties.

Still according to the invention, layer 12 of acrylic resin may undergo a UV treatment, preventing degradation of the underlying product forming support 11.

In a particular embodiment of the invention, the acrylic resin forming layer 12 and including an aqueous dispersion of inorganic charges, titanium dioxide, calcium carbonate, talc, hollow glass microspheres in an acrylic styrene resin further includes a dispersion of acrylic copolymer to which wetting and levelling waxes are added. Advantageously, the addition of a dispersion of acrylic copolymer to which wetting and levelling waxes have been added gives a glossy finishing to layer 12. Said glossy finishing has exhibited considerable dirt-repelling properties and further contributes to improving the duration of the original properties of the product.

According to the invention, the material forming support layer 11 is chosen out of non-woven polyester material (PET) with continuous filament or neutral staple or staple possibly woven with a net of glass textile or longitudinal and non-longitudinal glass filaments, neutral polypropylene (PP), or polypropylene possibly woven with a net of glass textile or longitudinal and non-longitudinal glass filaments, neutral polyamide (PA) or polyamide possibly woven with a net of glass textile or longitudinal and non- longitudinal glass filaments, neutral cotton or cotton possibly woven with a net of glass textile or longitudinal and non-longitudinal glass filaments, neutral plastic film or plastic film possibly woven with a net of glass textile or longitudinal and non- longitudinal glass filaments, neutral fabric or fabric possibly woven with a net of glass textile or longitudinal and non-longitudinal glass filaments, neutral glass web or glass web possibly woven with a net of glass textile or longitudinal and non-longitudinal glass filaments, neutral glass textile or glass textile possibly woven with a net of glass textile or longitudinal and non- longitudinal glass filaments.

Referring to Fig. 2, according to another embodiment of the coating material according to the invention, a layer 13 with dimensional stabilisation properties, comprising a net of glass textile, of polyester (PET), of polypropylene (PP) or of other textile and/or plastic materials is interposed between layers 11 and 12. Advantageously, said layer 13 may be embodied into layer 12 of acrylic resin, like in the example schematically shown.

Preferably, the application of layer 12 takes place by direct spreading over the material forming layer 11 or 13 and subsequent drying in a controlled environment.

Referring to Fig. 3, there is shown a particular embodiment of the material according to the invention, further comprising a layer 14 consisting of an adhesive, preferably of the type used for recovering or repairing waterproofing surfaces, for instance a hot-melt adhesive. Layer 14 is superimposed on the face of layer 11 opposite to the face coated with layer 12 and/or 13.

The application of adhesive layer 14, if any, may take place simultaneously with or separately from the steps in which layers 12 and 13 are applied.

A layer 15 of a silicone-based film is provided in order to protect layer 14 before applying the coating material to the waterproofing surface.

The material obtained in this manner is a layered composite material, flexible and in the form of a sheet, a ribbon or square plates, and it can be applied to different surfaces such as, for instance, bituminous membranes, polyethylene, metal sheet. Always in accordance with the invention, the material can be produced in any shape and size, for instance even in the shape of strips of reduced width, for instance about 100 mm, for repairs or for use as joining elements.

Referring now to Fig. 4, a plant 31 for manufacturing the layered composite material according to the third embodiment of the invention is schematically shown. In plant 31 , support material 11 is unwound from a roll 32 and arranged preferably horizontal. Net material 13, which is in turn unwound from a corresponding roll 33, is arranged onto horizontal support layer 31. A spreading station 34 for the layer of acrylic resin 12 is provided downstream the region where layers 11 and 13 converge, so as to impregnate net 13 and coat a first face of layer 11. The other face of layer 11, i.e., the face not coated wit resin layer 12, is coated with an adhesive layer 14 in a station 35, again by spreading. A drying station 37 is provided downstream spreading station 35 in order to dry the resin and the adhesive and, for this reason, it is passed through by the layered composite material in order the drying can occur on both faces of the layered material. Dried layer 14 is subsequently coated with a layer 15 of silicone-based protective film unwound from a roll 36. A collecting station 38, in which the coating material is wound into a roll, is provided downstream the region where film 15 is joined.

Even though plant 31 has been disclosed with reference to the third embodiment of the material according to the invention, also the materials according to the first and second embodiments can however be obtained by means of the same plant with simple modifications.

The layered composite material obtained in this manner can be advantageously applied onto a waterproofing material, in particular a bituminous sheath. Preferably, the waterproofing sheath is previously cleaned and/or washed, then film 15 is removed from the layered material in order to expose adhesive layer 14. At this point, the material can be advantageously applied onto and made to adhere to the surface to be coated, in particular a bituminous sheath, so as to impart the desired appearance to said sheath.

In a variant embodiment of the invention, a film of plastic material or polyethylene or polypropylene can be optionally provided between layer 11 and adhesive layer 14 in order to prevent migration of the bituminous mixture towards layer 11, once the coating material has been applied. Such a film is denoted by reference numeral 17 in Fig. 4, but it could be provided also in the other embodiments described herein. Such a film can be made to adhere to layer 12 by means of an adhesive dried in station 37 during working.