Patent Description:
As known, there are glass slabs that are usable in construction industry for coating exteriors in general or even for coating indoor environments.

In this regard, are known decorative multi-layer slabs which in addition to the support glass layers, typically an upper one facing the surrounding environment and the other one lower facing instead the surface or structure to which the coating slab is fixed, have a decorative film positioned between the two support layers.

A natural technological evolution of these coating slabs, considering that they are surfaces, even very large, exposed to the sun for several hours a day, was represented by providing these multi-layer coating slabs with photovoltaic cells either fixed to the outer surface exposed to the sun or inside the multi-layer structure, so as to convert the solar radiation incident on the coating slab into electricity.

However, the problem of dispersion of solar radiation is still apparent, making these coating panels or slabs unsatisfactory based on the increasingly demanding market needs, which, in addition to efficiency from a technological point of view, also require high quality even from an esthetic point of view.

Therefore, there is an increasingly felt need to have a multi-layer coating slab, which is reliably and efficiently capable of converting solar radiation into electricity, reducing the dispersion of solar radiation as much as possible, while simultaneously maintaining a remarkable esthetic effect.

<CIT> Al relates to a photovoltaic device capable of converting incident radiation, especially solar radiation, into electricity by means of solar (or photovoltaic) cells.

It is the object of the present invention to devise and provide a multi-layer coating slab, which allows to solve at least partially the drawbacks claimed above with reference to the art, and which is capable of reliably and efficiently ensuring a conversion of solar radiation into electricity with high performance, while simultaneously maintaining a significant transparent, semi-transparent, and non-transparent esthetic effect.

Such an object is achieved by a multi-layer coating slab according to claim <NUM>.

Preferred embodiments of such a coating slab are defined in the dependent claims.

Further features and advantages of the multi-layer coating slab according to the invention will become apparent from the following description of preferred embodiments, given by way of indicative, non-limiting examples, with reference to the accompanying drawings, in which:.

It should be noted that, in the aforesaid figures, equivalent or similar elements are indicated by the same numeric and/or alphanumeric reference.

With reference to the aforesaid <FIG> and 2a-2d, a multi-layer coating slab (or sheet), hereafter even only multi-layer slab or simply slab, according to the invention as a whole and in further embodiments, is indicated by numerical reference <NUM>.

In general, the slab <NUM> can be defined as a decorative transparent, semi-transparent, and non-transparent multi-layer coating slab.

Furthermore, the slab <NUM>, as it will be also described below, in addition to ensuring a decorative (transparent, semi-transparent, and non-transparent) effect, is capable of performing technological functions.

The slab <NUM> has a main extension plane P.

In an embodiment of the present invention, said main extension plane P has a planar geometry.

In a further embodiment of the present invention, as an alternative to the previous one, said main extension plane P has a curved geometry.

Said curved geometry is characterized by the specific curvature, defined in each point thereof as a function of the radius of curvature.

The presence of optical distortions due to the curved geometry of the main extension plane P is a function of the thickness of the slab <NUM>, defined along the direction perpendicular to said main extension plane P, and of the radius of curvature.

Optimizing the thickness and radius of curvature parameters, it is possible to obtain different optical distortion values for the slab <NUM>.

In an embodiment, the main extension plane P has a curved geometry characterized by a constant radius of curvature.

According to the previous embodiment, the curved geometry of said main extension plane P is a function of the radius of curvature and angle of curvature parameters.

Preferably, the minimum radius of curvature is <NUM>.

Even more preferably, the minimum radius of curvature is <NUM>.

Preferably, the angle of curvature is between <NUM> and <NUM> degrees, even more preferably between <NUM> and <NUM> degrees.

Each layer of the slab <NUM> extends parallel to the main extension plane P.

For this reason, any one of the layers of the slab <NUM> is indicated in <FIG>, <FIG>, <FIG>, and <FIG> as the main extension plane P of the slab <NUM>.

The main extension plane P is symbolically indicated by a dotted line in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and 8b.

The slab <NUM> along a direction D (indicated in the figures by an arrow), substantially perpendicular to the main extension plane P, comprises a first transparent material layer <NUM> having a first surface S1 and an opposing second surface S2.

The first surface S1, when the slab <NUM> is in use, faces the surrounding environment A to be exposed to solar radiation RS (also symbolically represented by an arrow in the figures).

The first transparent material layer <NUM> has a thickness, for example, in the range from <NUM> to <NUM>.

The first transparent material layer <NUM> is, for example, glass or any other transparent polymer material, such as polymethylmethacrylate, polycarbonate, and so on.

Preferably, said first transparent material layer <NUM> is a solar glass, known per se.

The first transparent material layer <NUM> is suitable for performing a protective function since it is resistant to weathering, chemical products, and so on.

In an embodiment, the first transparent material layer <NUM> comprises a micro-prismatic surface.

Such a micro-prismatic surface comprises geometric micro-imperfections of variable shape, depth and direction on the surface of the first transparent material layer <NUM>.

Such a micro-prismatic surface has the function of reducing the reflections and optimizing the transfer of the sun's rays inside the slab <NUM>.

In a further embodiment, the first transparent material layer <NUM> comprises a nanometric anti-reflective coating.

Such a nanometric anti-reflective coating has the function of decreasing the natural surface reflection component of the glass.

Preferably, said micro-prismatic surface and said anti-reflective coating are made on the first surface S1 of the first transparent material layer <NUM>.

The slab <NUM>, along the direction D substantially perpendicular to the main extension plane P, further comprises a second transparent material layer <NUM> having a respective first surface S3 and an opposing second surface S4.

When the slab <NUM> is in use, the second surface S4 faces a support structure or surface (not shown in the figure) onto which the slab <NUM> is installable.

The second transparent material layer <NUM> has a thickness, for example, in the range from <NUM> to <NUM>.

The second transparent material layer <NUM> is, for example, glass or any other transparent polymer material, such as polymethylmethacrylate, polycarbonate, and so on.

The second transparent material layer <NUM> is suitable for performing a protective function since it is resistant to weathering, chemical products, and so on.

The slab <NUM>, again along the direction D, substantially perpendicular to the main extension plane P, further comprises at least a first intermediate solar radiation concentrating layer <NUM>, interposed between the first transparent material layer <NUM> and the second transparent layer <NUM> and delimited by a peripheral edge B3.

The at least a first intermediate layer <NUM> comprises a distribution of nanoparticles therein so as to deviate a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>. Specifically, the at least a first intermediate layer <NUM> comprises a distribution of nanoparticles therein such as to absorb a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> and re-emit it isotropically at greater wave lengths.

Part of the solar radiation RS re-emitted by the nanoparticles is conveyed in a beam orthogonal to the source towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>.

The at least a first intermediate layer <NUM> has, for example, a thickness in the range from <NUM> to <NUM>.

The at least a first intermediate layer <NUM> is made of any polymer material, in which it is possible to distribute nanoparticles therein.

Examples of such a polymer material include polymethylmethacrylate, polycarbonate, pteg, and so on.

Nanoparticles mean nanocrystals or nanostructures adapted to deviate a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> towards the peripheral edge B3 of the at least a first intermediate layer <NUM>.

Nanoparticles means nanocrystals or nanostructures adapted to absorb a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> and re-emit said solar radiation RS at greater wavelengths towards the peripheral edge B3 of the at least a first intermediate layer <NUM>.

Preferably, said distribution of particles re-emits the solar radiation isotropically at greater wavelengths in the range between <NUM> and <NUM>.

Said nanoparticles can have an organic or inorganic origin.

Examples of nanocrystals or nanostructures adapted to absorb a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> and re-emit it isotropically at greater wavelengths towards the peripheral edge B3 of the at least a first intermediate layer <NUM>, are, for example, nanocrystals of perovskite doped with Mn<NUM>+ or nanocrystals of perovskite CsPbCl<NUM> with a convenient level of doping.

Returning to the slab <NUM> according to the present invention, again with reference to the figures, the slab <NUM>, again along the direction D, substantially perpendicular to the main extension plane P, further comprises at least a second decorative intermediate layer <NUM> (transparent, semi-transparent and non-transparent) interposed between the at least a first intermediate layer <NUM> and the second transparent material layer <NUM>.

The at least a second decorative intermediate layer <NUM> has a thickness, for example, in the range from <NUM> to <NUM>.

According to the present invention, said at least a second decorative intermediate layer <NUM> comprises a distribution of a decorative component adapted to determine, along a direction parallel to said main extension plane P, a gradient of opacity.

The degree of transparency of the slab <NUM> is inversely proportionate to the amount of decorative component placed in the at least a second decorative intermediate layer <NUM>.

Advantageously, the distribution of said decorative component inside said at least one decorative intermediate layer is not uniform, so that there are portions with a greater density of decorative component, portions with a smaller density of decorative component and/or portions in which the decorative component is not present, corresponding to opaque portions, semi-transparent portions and completely transparent portions, respectively.

According to a preferred embodiment, said distribution of said decorative component determines, along a direction parallel to said main extension plane P, a gradient of opacity with increasing opacity going from the center of the slab <NUM> to the peripheral edge.

According to a preferred embodiment, said at least a second decorative intermediate layer <NUM> is completely opaque for a portion close to the peripheral edge of the slab <NUM>.

The term "portion close to the peripheral edge of the slab" means a completely opaque portion of said at least a second decorative intermediate layer <NUM>, which extends from said peripheral edge of the slab <NUM> towards the center of the slab <NUM> over a set distance, such as to preserve the transparent and decorative features in the central portion of the slab <NUM>.

Preferably, the set distance from said peripheral edge of the slab <NUM> is equal to at least <NUM> so as not to affect the transparency and decoration.

Completely opaque means a zone in which the transmittance of the light is about0.

The transmittance of the light is defined as the capacity of a material to be crossed by part of the incident light.

According to this embodiment, the at least a second decorative intermediate layer <NUM> is completely opaque close to the peripheral edge of the slab <NUM> by virtue of the greater amount of decorative component present close to the peripheral edge of the decorative intermediate layer.

The at least a second decorative intermediate <NUM> layer is, for example, any transparent polymer material, such as polymethylmethacrylate, polycarbonate, pteg, and so on.

The decorative component present in the at least a second decorative intermediate layer <NUM> is, for example, a printed polymer decoration, a decorative metal or non-metal fabric (e.g., nets), and so on.

The decorative metal fabric comprises a metal component, preferably in the form of interwoven fibers, optionally coated.

Preferably, the decorative component present in the at least a second decorative intermediate layer <NUM> comprises pigments of different colors therein.

Returning to the slab <NUM> according to the present invention, with particular reference to <FIG>, the slab <NUM> further comprises at least one photovoltaic element <NUM> fixed to the slab <NUM> so that at least one portion of the photovoltaic element <NUM> overlaps a portion of the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM> to convert the solar radiation RS re-emitted by the nanoparticles and conveyed in a beam orthogonal to the source towards the peripheral edge B3 into electricity E-E, e.g., an electric current or electric voltage.

The at least one photovoltaic element <NUM> is fixed to the slab <NUM> by gluing or in adherence through mechanical fixing.

According to a further embodiment, in combination with the previous one and shown in <FIG>, the at least one photovoltaic element <NUM> comprises a strip of photovoltaic elements fixed to the slab so that the strip of photovoltaic elements overlaps the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM> to convert the solar radiation RS re-emitted by the nanoparticles and conveyed in a beam orthogonal to the source towards the peripheral edge B3 into electricity E-E.

Preferably, said at least one photovoltaic element <NUM> overlaps parallel and orthogonal to the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>.

In this embodiment, in which the photovoltaic element <NUM> completely overlaps the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>, a greater efficiency of the slab <NUM> is ensured since a greater amount of solar radiation RS is converted into electricity E-E.

According to an embodiment, in combination with the previous one and shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and 8b, the slab <NUM> further comprises an auxiliary solar radiation reflecting layer <NUM>, interposed below said at least a first intermediate layer <NUM>.

The auxiliary solar radiation reflecting layer <NUM> has an inner composition such as to reflect the set spectral component of the solar radiation RS, dispersed beyond the at least a first intermediate solar radiation concentrating layer <NUM>, towards said at least a first intermediate solar radiation concentrating layer <NUM>.

In other words, the auxiliary solar radiation reflecting layer <NUM> performs the function of an interfering mirror and advantageously allows reflecting again, towards the at least a first intermediate solar radiation concentrating layer <NUM>, thus recovering, the solar radiation that, not having been conveyed in a beam orthogonal to the source by the at least a first intermediate solar radiation concentrating layer <NUM> towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>, was dispersed below the at least a first intermediate solar radiation concentrating layer <NUM>, increasing the efficiency and reliability of the slab <NUM> in terms of reduction of the solar radiation dispersion and performance in terms of generation of electricity from solar radiation.

Preferably, the auxiliary solar radiation reflecting layer <NUM> has an inner composition such as to reflect the spectral component of the solar radiation RS related to the near field infrared.

The auxiliary solar radiation reflecting layer <NUM> has, for example, a thickness in the range from <NUM> to <NUM>. The auxiliary solar radiation reflecting layer <NUM> is a transparent material, such as glass or other transparent polymer material, such as polymethylmethacrylate, polycarbonate, pteg, and so on.

It should be noted that the mirror interfering effect at the set spectral component adapted to cause the operation of the nanoparticles distributed inside the at least a first intermediate solar radiation concentrating layer <NUM> can also be obtained by a coating of a layer made of a polymer or glass material.

According to an embodiment, in combination with the previous one and shown in <FIG>, <FIG>, <FIG>, the auxiliary solar radiation reflecting layer <NUM> is interposed between the at least a first intermediate solar radiation concentrating layer <NUM> and the at least a second decorative intermediate layer <NUM>.

Advantageously, the solar radiation possibly dispersed below the at least a first intermediate solar radiation concentrating layer <NUM> and reflected by the auxiliary solar radiation reflecting layer is thus prevented from damaging the decoration made on the at least a second auxiliary decorative layer <NUM>, keeping the overall esthetic appearance of the slab <NUM> unaltered for longer in time.

According to an embodiment, as an alternative to the previous one and shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and 8b, the auxiliary solar radiation reflecting layer <NUM> is arranged below the at least a second decorative intermediate layer <NUM>.

According to an embodiment, in combination with the previous one and shown in <FIG>, <FIG> and <FIG>, the auxiliary solar radiation reflecting layer <NUM> is interposed between the at least a second decorative intermediate layer <NUM> and the second transparent material layer <NUM>.

According to an embodiment, as an alternative to the previous one and shown in <FIG>, <FIG> and 8b, the auxiliary solar radiation reflecting layer <NUM> is arranged below the second transparent material layer <NUM>.

According to a further embodiment, as an alternative to the previous ones and not shown in the figures, the auxiliary solar radiation reflecting layer <NUM> coincides with the second transparent material layer <NUM>.

According to an embodiment, in combination with any one of those described above and shown in any one of <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, 8b, the slab <NUM> further comprises a plurality of adhesive material layers AV.

Each layer of the multi-layer slab <NUM> is fixed to a layer adjacent thereto by means of an adhesive material layer of said plurality of adhesive material layers AV, interposed between the layer and the layer adjacent thereto.

Each adhesive material layer has a thickness, for example, in the range from <NUM> to <NUM>.

Examples of adhesive material include ethyl vinyl acetate, polyvinyl butyral, polyolefins, adhesives, and transparent resins, such as acrylics, epoxies, ms polymers, silicones and so on.

Referring now to <FIG>, a process for manufacturing a multi-layer coating slab according to the present invention is now described.

The manufacturing process comprises positioning the layers forming the multi-layer slab, i.e., the first transparent material layer <NUM>, the second transparent material layer <NUM>, the at least a first intermediate solar radiation concentrating layer <NUM>, the at least a second decorative intermediate layer <NUM>, and possibly, if present, the auxiliary solar radiation reflecting layer <NUM> (in one of the positions provided according to the different embodiments previously described).

During the positioning, an adhesive material layer of the plurality of adhesive material layers, which can be provided inside the slab <NUM>, is interposed between adjacent layers.

The slab <NUM> thus assembled undergoes cooking in a furnace with depression/pressure control according to a time trend of the operating temperature of the furnace, which comprises a first heating step, a second heating step, a third heating step, and a fourth cooling step, specifically studied to favor the polymerization of the material, preventing it from further de-laminating.

Once cooled, the at least one photovoltaic element <NUM> is fixed to the slab <NUM>.

With reference to <FIG>, an example of technological operation of the slab <NUM> is now described according to an embodiment of the present invention.

The slab <NUM> is applied to an outer wall of a building (not shown in the figure) and the at least one photovoltaic element is electrically connected with an apparatus for distributing electricity of the building, symbolically shown in the figure by a lightbulb.

The solar radiation RS incises the slab <NUM>, and after reaching the at least a first intermediate solar radiation concentrating layer <NUM>, a set spectral component is deviated towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>, thus towards the at least one photovoltaic element <NUM>.

The at least one photovoltaic element <NUM> converts the solar radiation received into electricity supplied to the electricity distribution apparatus.

It should be noted that the multi-layer coating slab according to the present invention can be applied to facades of buildings, parapets, balconies, verandas, and external coatings in general, skylights, coverings in general such as projecting roofs, partitions, and generally to all possible applications of glass, both outside and inside.

As can be seen, the object of the invention is fully achieved.

First, the decorative (transparent, semi-transparent and non-transparent) multi-layer coating slab, according to the present invention, maintains the decorative appearance, while ensuring an improved conversion of the solar radiation as compared to known technologies.

In fact, in one embodiment, the presence of the first layer of anti-reflecting solar glass increases the optical transmission and reduces the phenomena of the diffusion of incident radiation.

Furthermore, the presence of the at least a first intermediate solar radiation concentrating layer <NUM> inside the multi-layer slab and interposed between the first transparent material layer <NUM> and the second transparent layer <NUM>, where the at least a first intermediate layer <NUM> comprises a distribution of nanoparticles therein, so as to absorb a set spectral component of the solar radiation RS from the surrounding environment A and incident on the first transparent material layer <NUM> and re-emit it at greater wavelengths towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>, advantageously allows reliably collecting the solar radiation towards the peripheral edge, which is converted into electricity by the at least one photovoltaic element <NUM> fixed to the slab <NUM> at the peripheral edge of the at least one intermediate solar radiation concentrating layer <NUM>.

Advantageously, the provision of at least a second decorative intermediate layer <NUM>, comprising a distribution of a decorative component adapted to determine a gradient of opacity along a direction parallel to said main extension plane P, allows the light radiation absorbed by the nanoparticles embedded in said at least a first intermediate solar radiation concentrating layer <NUM> and re-emitted towards the peripheral edge of the solar radiation concentrating layer to be forced to remain inside the peripheral edge of said solar concentrating layer, so as to increase the efficiency of said at least one photovoltaic element <NUM> fixed to the peripheral edge B3 of the at least a first intermediate concentrating layer <NUM>.

Advantageously, said at least a second decorative intermediate layer <NUM> according to the invention comprising a non-uniform distribution of said decorative component forms a slab with different degrees of transparency and increased esthetic appearance as compared to traditional slabs.

Advantageously, the distribution of the decoration is completely opaque close to the edges of the at least a second decorative intermediate layer <NUM>, for a better solar concentration efficiency on the surface of the photovoltaic devices, thus reducing the effect of diffusion through the surfaces of the layer.

Advantageously, no further glass processing, such as etching or glazing, is required in order to obtain the opaque effect.

Furthermore, in a further embodiment, the additional presence of the auxiliary solar radiation reflecting layer <NUM> (interfering mirror) advantageously allows reflecting, again towards the at least a first intermediate solar radiation concentrating layer <NUM>, then recovering, any solar radiation that, not having been deviated by the at least a first intermediate solar radiation concentrating layer <NUM> towards the peripheral edge B3 of the at least a first intermediate solar radiation concentrating layer <NUM>, was dispersed below the at least a first intermediate solar radiation concentrating layer <NUM>.

The efficiency and reliability of the slab <NUM> are certainly increased in terms of reducing the dispersion of solar radiation and performance in terms of generating electricity from solar radiation.

Claim 1:
A multi-layer coating slab (<NUM>) having a main extension plane (P), said slab (<NUM>), along a direction (D) substantially perpendicular to the main extension plane (P), comprising:
- a first transparent material layer (<NUM>) having a first surface (S1) and an opposing second surface (S2), the first surface (S1), when the slab (<NUM>) is in use, facing the surrounding environment (A) in order to be exposed to solar radiation (RS);
- a second transparent material layer (<NUM>) having a respective first surface (S3) and an opposing second surface (S4), when the slab (<NUM>) is in use, the second surface (S4) facing a support surface or structure onto which the slab (<NUM>) is installable;
- at least a first intermediate solar radiation concentrating layer (<NUM>), interposed between the first transparent material layer (<NUM>) and the second transparent material layer (<NUM>) and delimited by a peripheral edge (B3), said at least a first intermediate layer (<NUM>) comprising a distribution of nanoparticles therein so as to absorb a set spectral component of the solar radiation (RS) from the surrounding environment (A) and incident on the first transparent material layer (<NUM>) and re-emit it at greater wavelengths towards the peripheral edge (B3) of the at least a first intermediate solar radiation concentrating layer (<NUM>);
- at least a second intermediate layer (<NUM>) interposed between the at least a first intermediate layer (<NUM>) and the second transparent material layer (<NUM>),
- at least one photovoltaic element (<NUM>), said at least one photovoltaic element (<NUM>) comprising a strip of photovoltaic elements fixed to the slab (<NUM>) so that the strip of photovoltaic elements overlaps one portion of the peripheral edge (B3) of the at least a first intermediate solar radiation concentrating layer (<NUM>) to convert the solar radiation (RS) re-emitted towards the peripheral edge (B3) into electricity (E-E),
characterized in that
said at least a second intermediate layer (<NUM>) is a decorative layer and comprises a distribution of a decorative component adapted to determine, along a direction parallel to said main extension plane (P), a gradient of opacity.