Patent Description:
In particular the present invention relates to a polymeric composition comprising a polymeric elastomeric phase and a fluorescent dye and use.

The present invention concerns also objects or articles comprising a polymeric composition comprising a polymeric elastomeric phase and a fluorescent dye.

The present invention concerns as well a photovoltaic module comprising a polymeric composition comprising a polymeric elastomeric phase and a fluorescent dye.

It is of great interest to have polymeric compositions for photovoltaic application and photovoltaic modules and use them in photovoltaic application and photovoltaic modules, as polymers have a density that is less important than glass, for producing more light weight structures.

One type of photovoltaic module is based on luminescent solar concentrators (LSCs).

Furthermore it is of great interest to have long lasting photovoltaic modules that are efficient, resist highly to impacts, stay transparent independently of the temperature and possess an increased flexibility.

Another important point is that the photovoltaic modules should work for several years and not lose their performance.

The objective of the present invention is to provide a polymeric composition that resist highly to impacts, stay transparent independently of the temperature and possess an increased flexibility and that can absorb light and reemit it.

A further objective of the present invention is to provide a polymeric composition with that can absorb light and reemit it and does not lose this property with aging.

Still another object of the present invention is to use a polymeric composition that resist highly to impacts, stay transparent independently of the temperature and possess an increased flexibility and that can absorb light and reemit it and does not lose this last property with aging, in a photovoltaic application.

Another objective of the present invention is to provide an object that comprises a polymeric composition that resist highly to impacts, stay transparent independently of the temperature and possess an increased flexibility and that can absorb light and reemit it and does not lose this last property with aging.

Again still another objective of the present invention is a photovoltaic module that resist highly to impacts, stay transparent independently of the temperature and possess an increased flexibility and that can absorb light and reemit it and does not lose this last property with aging.

The american patent application <CIT> discloses fluorescent solar conversion cells based on fluorescent terylene dyes. The dyes are used to dope polymer panels or are comprised in polymer coatings for glass panels, said polymers are transparent colourless thermoplastic polymers. Suitable polymers include acrylic resins, styrene polymers, polycarbonates, polyamides, polyesters, thermoplastic polyurethanes, polyethersulfones, polysulfones, vinyl polymers, or mixtures thereof. Impact modification is mentioned as well.

The american patent application <CIT> describes polymethyl (meth)-acrylate mouldings for fluorescence conversion, production of these and sheets by casting process and use in solar collectors. The castings can also be preferred impact modified castings, containing between <NUM> wt% and <NUM> wt% of an impact modifier. The impact modifiers used, are crosslinked polymer particles.

The international patent application <CIT> discloses a stack of layers comprising luminescent material, a lamp, a luminaire and a method of manufacturing the stack of layers. The luminescent layer is sandwiched between the first outer layer and the second outer layer and comprises a light transmitting matrix polymer and a luminescent material. The light transmitting polymeric material comprises at least one of: poly ethylene terephthalate (PET), poly ethylene naphtalate (PEN), poly vinylidene chloride (PVDC), poly vinylidene fluoride (PVDF), ethylene vinyl alcohol (EVOH), polybutylene terephthalate (PBT), poly acrylo nitrile (PAN) and nylon6 (PA6) and optionally, the polymeric material comprises at least one of: poly ethylene terephthalate (PET), polymethyl methacrylate (PMMA), poly carbonate (PC).

The international patent application <CIT> describes a process for the impregnation of polymer substrates. The impregnation process includes at least one organic compound. The impregnated polymer obtained from such a process can be used in luminescent solar concentrators. Preferred polymers are selected from polyacrylates, polycarbonates, polystyrenes, styrene-acrylonitrile copolymers, or mixtures thereof. An elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM> is not mentioned.

In the prior art no compositions are described having a combination of a polymeric phase, an elastomeric phase and a fluorescent dye according to the present invention.

Furthermore no loss of power during aging is mentioned in any of the cited prior art documents.

Surprisingly, it has been discovered that a composition comprising a polymeric phase having a glass transition temperature of at least <NUM>, an elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, and a fluorescent dye, is performing efficient in a luminescent solar concentrators while having good mechanical properties aging performance.

It has also been found that a composition comprising a polymeric phase having a glass transition temperature of at least <NUM>, an elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, and a fluorescent dye, can be used in a photovoltaic module.

According to a first aspect, the present invention relates to a composition comprising:.

According to a second aspect, the present invention relates to an article comprising a composition comprising:.

According to another aspect, the present invention relates to the use of a composition comprising:.

An additional aspect of the present invention is a photovoltaic module comprising a composition comprising:.

By the term "polymeric elastomeric phase" as used herein, is denoted the thermodynamic state of the polymer above its glass transition temperature.

By the term "alkyl(meth)acrylate" as used herein, is denoted the to both alkyl acrylate and alkyl methacrylate.

By the term "copolymer" as used herein, is denoted that the polymers consists of at least two different monomers.

By the term "parts" as used herein, is denoted "parts by weight".

By the term "thermoplastic polymer" as used herein, is denoted a polymer that turns to a liquid or becomes more liquid or less viscous when heated and that can take on new shapes by the application of heat and pressure.

By the term "PMMA" as used herein, are denoted homo- and copolymers of methyl methacrylate (MMA), for the copolymer of MMA the weight ratio of MMA inside the PMMA is at least <NUM> wt%.

By the term "fluorescent dye" as used herein, is denoted an organic molecule which has the characteristic of absorbing light and of reemitting it.

By the term "transparent or light transmitting" as used herein, is denoted a material that has a total light transmittance of at least <NUM>% according to ASTM D1003-<NUM> for a sheet made out of this material having a thickness of <NUM>.

The composition according to the present invention comprises a) a polymeric phase having a glass transition temperature of at least <NUM>, b) an elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, and c) a fluorescent dye.

With regard to elastomeric phase of macromolecular sequences having a flexible nature, said macromolecular sequences have a glass transition temperature of less than <NUM>, preferably of less than <NUM>, more preferably of less than <NUM>, advantageously of less than -<NUM>, and more advantageously of less than -<NUM>.

The elastomeric phase in the composition according to the present invention can be a continuous phase, a semi-continuous phase, or a discontinuous phase.

According to the present invention, the macromolecular sequence with the flexible nature forming the elastomeric phase is part of a block copolymer with at least one block having a glass transition temperature of less than <NUM>, preferably of less than <NUM>, more preferably of less than <NUM>, advantageously of less than -<NUM>, and more advantageously of less than -<NUM>.

The block copolymer is selected from a thermoplastic block copolymer. The thermoplastic block copolymer comprises at least one block which is an acrylic block. By this, is meant that at least <NUM> wt% of the monomers inside this block are alkyl(meth)acrylate monomers, that have been polymerized.

Advantageously, the block copolymer is amorphous. More advantageously, the block copolymer does not comprise any semicrystalline or crystalline blocks.

Most preferably, the thermoplastic block copolymer is a thermoplastic acrylic block copolymer. By this, is meant that at least <NUM> wt% of the monomers inside thermoplastic acrylic block copolymer are alkyl(meth)acrylate monomers, that have been polymerized.

The thermoplastic acrylic block copolymer has a general formula (A)nB in which:.

Advantageously, the block copolymer is amorphous.

Preferably, in the block A the monomer is selected from methyl methacrylate (MMA), phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, styrene (Sty), or alphamethylstyrene, or mixtures thereof. More preferably, the block A is PMMA, or PMMA copolymerized with acrylic or methacrylic comonomers, or polystyrene (PS), or polystyrene (PS) modified with styrenic comonomers.

Preferably the block B comprises monomers selected from methyl acrylate, ethyl acrylate, butyl acrylate (BuA), ethylhexyl acrylate, or butyl methacrylate, or mixtures thereof, more preferably butyl acrylate said monomers make up at least <NUM> wt%, preferably <NUM> wt% of block B.

Furthermore, the blocks A and/or B, can comprise other acrylic or methacrylic comonomers carrying various chemical function groups known to a person skilled in the art, for example acid, amide, amine, hydroxyl, epoxy, or alkoxy, functional groups. The block A can incorporate groups, such as acrylic acid, or methacrylic acid, in order to increase the temperature stability of thereof.

Comonomers like styrene can also be incorporated in the block B in order to mismatch the refractive index of the block A.

Preferably, said thermoplastic acrylic block copolymer has a structure selected from: ABA, AB, A<NUM>B and A<NUM>B.

The thermoplastic acrylic block copolymer for example can be one of the following triblock copolymers: pMMA-pBuA-pMMA, p(MMAcoMAA)-pBuA-p(MMAcoMAA), p(MMAcoMAA)-p(BuAcoSty)-p(MMAcoMAA) and p(MMAcoAA)-pBuA-p(MMAcoAA). In a preferred embodiment, the block copolymer is of MAM type (PMMA-pBuA-PMMA).

It is known to a person skilled in the art that the polymers of PMMA type can comprise small amounts of acrylate comonomer in order to improve the temperature stability thereof. By small is meant less than <NUM> wt%, preferably less than <NUM> wt%, and more preferably less than <NUM> wt%, of the polymer.

The block B represents from <NUM>% to <NUM>%, preferably from <NUM>% to <NUM>%, of the total weight of the block copolymer.

The block B has a weight-average molar mass of between <NUM><NUM>/mol and <NUM><NUM>/mol, preferably of between <NUM><NUM>/mol and <NUM><NUM>/mol. The weight average molar mass can be measured by size exclusion chromatography (SEC).

The block copolymers participating in the composition of the matrix can be obtained by controlled radical polymerization (CRP) or by anionic polymerization; the most suitable process according to the type of copolymer to be manufactured will be selected.

Preferably, this will be CRP, in particular in the presence of nitroxides, for the block copolymers of (A)nB type and anionic or nitroxide radical polymerization, for the structures of ABA type, such as the triblock copolymer MAM. Controlled radical polymerization is described in the document for obtaining block copolymers, i.e. international patent application <CIT>.

According to the invention, the polymeric phase having a glass transition temperature of at least <NUM> is either the block A of the thermoplastic acrylic block copolymer as describe before or another thermoplastic polymer P1 or a mixture of both.

The thermoplastic polymer P1 is selected from polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinylidenefluoride (PVDF), poly (ethylene-vinyl acetate) (PEVA), or polyamide-grafted polyolefin.

Preferably, thermoplastic polymer P1 is selected from a homo- or copolymer of methyl methacrylate.

The thermoplastic polymer P1 can be crosslinked or not.

In a preferred embodiment the macromolecular sequence with the flexible nature forming the elastomeric phase is part of a polymer network. The network is crosslinked, preferably in the part of the network that is not the macromolecular sequence with the flexible nature forming the elastomeric phase.

Preferably, the macromolecular sequence with the flexible nature forming the elastomeric phase that is part of a polymer network represents between <NUM> wt% and <NUM> wt% of the polymer network comprising the macromolecular sequence with the flexible nature forming the elastomeric phase and the other polymer chains and crosslinkers making up the network.

Preferably, the macromolecular sequence with the flexible nature forming the elastomeric phase, which is part of a polymer network, is a thermoplastic acrylic sequence. By this is meant that at least <NUM> wt% of the monomers inside thermoplastic acrylic sequence are alkyl(meth)acrylate monomers.

The alkyl(meth)acrylate monomers of the macromolecular sequence with the flexible nature forming the elastomeric phase having a Tg of less than <NUM>, which is part of a polymer network, comprise monomers selected from methyl acrylate, ethyl acrylate, butyl acrylate (BuA), <NUM>-ethylhexyl acrylate, styrene or butyl methacrylate, or mixtures thereof. More preferably butyl acrylate make up at least <NUM> wt%, preferably <NUM> wt% of said monomers of the macromolecular sequence with the flexible nature forming the elastomeric phase having a Tg of less than <NUM>, which is part of a polymer network.

In this preferred embodiment, the polymeric phase having a glass transition temperature of at least <NUM> is also part of the network.

If crosslinked, the ratio of the crosslinking is sufficient low, so that the composition according to the present invention can be still thermoformed.

With regard to the fluorescent dye or optical active compound of the composition according to the present invention is an organic molecule.

Preferably, the fluorescent dye of the composition according to the present invention comprises at least one heterocyclic cycle. More preferably the hetero atom of the heterocyclic cycle is selected from N and/or S. The heterocyclic cycle can be aromatic or not.

According to a preferred embodiment of the present invention, the fluorescent dye or optical active compound is selected from photo luminescent dyes.

The photo luminescent dyes that can be used for the purpose of the present invention can be selected from photo luminescent dyes that absorb within the UV-visible range and emit within both the UV-visible and infrared range, and which are soluble and stable in the organic solvents immiscible with water indicated hereunder.

Advantageously, the photo luminescent dyes have a maximum of the absorption at a wavelength λabs between <NUM> and <NUM>, more advantageously between <NUM> and <NUM>.

Advantageously, the photo luminescent dyes have a maximum of the emitting at a wavelength λem between <NUM> and <NUM>, more advantageously between <NUM> and <NUM>.

Advantageously, the emitting wavelength λem of the photo luminescent dye is more important than its absorption wavelength λabs. More advantageously, the difference between the maximum of emitting wavelength λem and the maximum of absorption wavelength λabs of one photo luminescent dye is between <NUM> and <NUM>, more advantageously between <NUM> and <NUM>.

According to a more preferred embodiment of the present invention, said photo luminescent dyes can be selected, for example, from: perylene compounds known with the trade-name Lumogen® from BASF; acene compounds described, for example, in international patent application <CIT>; benzothiadiazole compounds, in particular <NUM>,<NUM>-di-(thien-<NUM>'-yl)-<NUM>,<NUM>,<NUM>-benzothiadiazole (DTB), described, for example, in international patent application <CIT>; compounds comprising a benzoetherodiazole group and at least one benzodithiophene group described, for example, in international patent application <CIT>; disubstituted naphthothiadiazole compounds described, for example, in european patent application <CIT>; benzoheterodiazole compounds disubstituted with benzodithiophene groups described, for example, in european patent application <CIT>; disubstituted benzoheterodiazole compounds described, for example, in international patent application <CIT>; disubstituted diaryloxybenzoheterodiazole compounds described, for example, in international patent application <CIT>.

Preferably, said photoluminescent dyes can be selected, for example, from: N,N'-bis(<NUM>',<NUM>'-di-iso- propylphenyl)(<NUM>,<NUM>,<NUM>,<NUM>-tetraphenoxy)(<NUM>,<NUM>,<NUM>,<NUM>-perylene-diimide (Lumogen® F Red <NUM> - Basf), <NUM>,<NUM>-di(thien-<NUM>'yl)-<NUM>,<NUM>,<NUM>-benzothiadiazole (DTB), <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis(<NUM>-thienyl)-<NUM>,<NUM>,<NUM>-benzothiadiazole (DTBOP), <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (MPDTBOP), <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (PPDTBOP), <NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (MPDTB), <NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-di-iso-propylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (IPPDTB), <NUM>,<NUM>-bis[<NUM>,<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (2MPDTB) <NUM>,<NUM>-bis(<NUM>',<NUM>'-dibutylbenzo[<NUM>',<NUM>'-b':<NUM>',<NUM>'-b"]dithien-<NUM>'-yl)-benzo[c] [<NUM>,<NUM>,<NUM>]thiadiazole (F500), <NUM>,<NUM>-bis(<NUM>',<NUM>'-dibutylbenzo[<NUM>',<NUM>'-b':<NUM>',<NUM>'-b"]dith-ien-<NUM>'-yl)-naphto[<NUM>,<NUM>-c] [<NUM>,<NUM>,<NUM>]thiadiazole (F521), <NUM>,<NUM>-bis(<NUM>-(thiophen-<NUM>-yl)thiophen-<NUM>-yl)benzo[c] [<NUM>,<NUM>,<NUM>]thiadiazole (QTB), <NUM>,<NUM>-bis(thien-<NUM>'-yl)-naphto [<NUM>, <NUM>-c] [<NUM>,<NUM>,<NUM>] thiadiazole (DTN), <NUM>,<NUM>- diphenylanthracene (DPA), or mixtures thereof. N,N'-bis(<NUM>',<NUM>'-di-isopropylphenyl)(<NUM>,<NUM>,<NUM>,<NUM>-tetraphenoxy)(<NUM>,<NUM>,<NUM>,<NUM>-perylene-diimide (Lumogen® F Red <NUM> - Basf) is particularly preferred. The composition according to the present invention comprises from <NUM> ppm to <NUM><NUM> ppm of the fluorescent dye, preferably from <NUM> ppm to <NUM><NUM> ppm, more preferably from <NUM> ppm to <NUM><NUM> ppm, still more preferably from <NUM> ppm to <NUM><NUM> ppm, based on the three compounds a), b) and c).

The elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, makes up at least <NUM> wt% of the composition, preferably at least <NUM> wt%, and more preferably at least <NUM> wt%, based on the three compounds a), b) and c).

The composition according to the present invention can optionally also comprise UV absorbers, UV stabilizers, radical inhibitors.

According to the present invention, the composition according to the present invention comprising the polymeric phase having a glass transition temperature of at least <NUM>, the elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, and the fluorescent dye as detailed before, is in form of as sheet.

The sheet comprising the composition of the present invention has a thickness of between <NUM> and <NUM>.

The concentration of the fluorescent dye in the composition is at least <NUM>*<NUM>-<NUM> ppm/mm<NUM> of the composition comprising the three components a), b) and c); preferably is at least <NUM>*<NUM>-<NUM> ppm/mm<NUM>.

The sheet can be flat, slightly bent or curved.

The composition according to the invention can be produced by a first method where the macromolecular sequence with the flexible nature forming the elastomeric phase is part of a block copolymer, comprises a blending step of the respective compounds.

This first method of preparation of the composition according to the present invention is blending the component comprising the elastomeric phase of macromolecular sequences having a flexible nature with the fluorescent dye, the polymeric phase having a glass transition temperature of at least <NUM> is already part of the blockcopolymer.

Optionally another thermoplastic polymer P1, selected from those reported above, could also be blended with.

The two or three components could be heated if necessary during blending.

Mixing could also be obtained by dry blending a solid resin comprising the elastomeric phase of macromolecular sequences having a flexible nature and composition comprising fluorescent dye.

The composition according to the present invention can be transformed by injection molding, extrusion or coextrusion for the preparation of sheets or films.

A second method of preparation of a composition according to the preferred embodiment of the present invention, where the macromolecular sequence with the flexible nature forming the elastomeric phase is part of a polymer network, comprises the steps of mixing the fluorescent dye with at least one monomer and macromolecular sequences having a flexible nature followed by a polymerisation step.

An example for this method for preparation of a composition according to the present invention would be a cast sheet polymerization wherein the fluorescent dye is mixed with the monomer or monomers and the other ingredients before the polymerization. Such a method, excluding the fluorescent dye, is describe in international patent application <CIT>.

As reported above, said polymeric composition can be advantageously used in photovoltaic module. Said photovoltaic module can be advantageously integrated in buildings and houses (for example, in photovoltaic windows, in photovoltaic skylights, in greenhouses, for both indoor and outdoor). Furthermore, said photovoltaic module can also be advantageously used as a functional element in urban and transport contexts (for example, in photovoltaic noise barriers, in photovoltaic windbreak, in photovoltaic cantilever roof).

Preferably, the composition according to the present invention is transparent. More preferably, the composition according to the present invention is transparent with a total light transmittance of <NUM>% or more, preferably <NUM>% or more, the total light transmittance being measured in accordance with ASTM D1003-<NUM> for a sample with <NUM> thickness.

The composition of the present invention can be used in articles.

The articles of the present invention can for example be in form of a sheet, block, film, tube, or profiled element.

The present invention concerns as well a photovoltaic module or device comprising the composition according to the present invention.

The present invention concerns as well a photovoltaic module comprising a layer comprising the composition according to the present invention.

The present invention concerns as well a photovoltaic module comprising a layer made of the composition according to the present invention.

The present invention concerns as well a photovoltaic module comprising a sheet comprising the composition according to the present invention.

The present invention concerns as well a photovoltaic module comprising at least one sheet made of the composition according to the present invention.

The photovoltaic module or device comprises also at least one photovoltaic cell, and at least one luminescent solar concentrator (LSC).

The weight average molecular weight of polymeric compound can be measure by size exclusion chromatography (SEC).

The glass transition temperature (Tg) of the polymers is measured with differential scanning calorimetry (DSC) according standard ISO <NUM>-<NUM>/<NUM>.

The thermomecahnical analysis are carried out by means of RDAII "RHEOMETRICS DYNAMIC ANALYSER" proposed by the Rheometrics Company. The thermo mechanical analysis measures precisely the visco-elastics changes of a sample in function of the temperature, the strain or the deformation applied. The apparatus records continuously, the sample deformation, keeping the stain fixed, during a controlled program of temperature variation.

The results are obtained by drawing, in function of the temperature, the elastic modulus (G'), the loss modulus and the tan delta. The Tg is higher temperature value read in the tan delta curve, when the derived of tan delta is equal to zero.

The ageing test is made according the standard procedure DIN EN ISO <NUM>-<NUM>-A1 <NUM>-<NUM> using an ATLAS XenoTest Beta+, equipped with a Xenon lamp air cooled and filtered by a Xenochrome <NUM> filter.

The maximum of the absorption at a wavelength λabs and the maximum of the emitting at a wavelength λem of photo luminescent dyes can obtained from a spectrum measured with a spectrofluorimeter.

The optical properties of the polymers are measured according to following method: light transmittance and haze are measured according to the standard ASTM D1003-<NUM>, sheets of <NUM> thickness.

The series of examples concern the preparation of PMMA sheets comprising and a fluorescent dye.

One sheet according to the invention comprises an elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, the comparative sheet does not comprise this elastomeric phase.

The PMMA sheets are prepared by cast polymerization of methyl methacrylate (MMA).

As fluorescent dye Lumogen® F Red <NUM> from BASF was used at <NUM> ppm in Example <NUM> and in Comparative Example <NUM>.

The sheet according to the present invention was prepared according to example test <NUM> of international patent application <CIT>.

The dimension of the sheets is <NUM> x <NUM> x <NUM>.

Two sheet samples of <NUM> x <NUM> x <NUM> were tested by measuring the average power generated by a photovoltaic cell, i.e. an IXYS-KXOB22-<NUM> photovoltaic cell having a surface area of <NUM><NUM> which was optically coupled at the center of the <NUM> edge. The samples were irradiated with the light generated by a Solar Simulator (<NUM> W/m<NUM> AM <NUM>). The light spot is <NUM> x <NUM> large and the sheet was irradiated perpendicularly to the <NUM> x <NUM> face. Several measurements were done moving the sheet in different position. The maximum power determined by a multimeter from J-V plots by plotting the power as a function of the distance d from the cell of the spot edge near the cell. An average power value <P> is calculated from the power values measured at different d values.

Then both samples are aged. The average power values <P> were evaluated for different ageing times of both samples.

The sample has an initial average power value <P> of <NUM> mW.

After <NUM> hours of ageing the sample has an average power value <P> of <NUM> mW.

After <NUM> hours of ageing the sample has an average power value <P> of <NUM> mW.

After <NUM> hours of ageing the sample has an average power value <P> of <NUM> mW.

The tests shows that the composition according to the invention performs good in such an application, and even better after ageing.

In the following examples, a sheet according to the present invention is prepared as in Example <NUM>, while using other dyes and other quantities of such dyes in the composition.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-di-(thien-<NUM>'-yl)-<NUM>,<NUM>,<NUM>-benzothiadiazole (DTB)] was used at <NUM> ppm.

The average power value <P> was <NUM> mW.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis(<NUM>-thienyl)-<NUM>,<NUM>,<NUM>-benzothiadiazole (DTBOP) was used at <NUM> ppm.

The average power value <P> was was <NUM> mW.

The average power value <P> was measured as above reported.

As fluorescent dye the <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (MPDTBOP) was used at 200ppm.

As fluorescent dye the <NUM>,<NUM>-diphenoxy-<NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (PPDTBOP) was used at <NUM> ppm.

As fluorescent dye the <NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-dimethylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (MPDTB) was used at <NUM> ppm.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-bis[<NUM>-(<NUM>,<NUM>-di-isopropylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (IPPDTB) was used at <NUM> ppm.

The average power value <P> was <NUM> mW.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-bis[<NUM>,<NUM>-(<NUM>,<NUM>-dimrthylphenyl)-<NUM>-thienyl]benzo[c]<NUM>,<NUM>,<NUM>-thiadiazole (2MPDTB) was used at <NUM> ppm.

As fluorescent dye the <NUM>,<NUM>-bis(<NUM>',<NUM>'-dibutylbenzo[<NUM>',<NUM>'-b':<NUM>',<NUM>'-b"]dithien-<NUM>'-yl)-benzo[c][<NUM>,<NUM>,<NUM>]thiadiazole (F500) was used at <NUM> ppm.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-bis(<NUM>',<NUM>'-dibutylbenzo[<NUM>',<NUM>'-b':<NUM>',<NUM>'-b"]dith-ien-<NUM>'-yl)-naphto[<NUM>,<NUM>-c][<NUM>,<NUM>,<NUM>]thiadiazole (F521) was used at <NUM> ppm.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-bis(<NUM>-(thiophen-<NUM>-yl)thiophen-<NUM>-yl)benzo[c] [<NUM>,<NUM>,<NUM>]thiadiazole (QTB) was used at <NUM> ppm.

The average power value <P> was measured as above reported. As fluorescent dye the <NUM>,<NUM>-bis(thien-<NUM>'-yl)-naphto[<NUM>,<NUM>-c][<NUM>,<NUM>,<NUM>]thiadiazole (DTN) was used at <NUM> ppm.

Claim 1:
A composition comprising
a) a polymeric phase having a glass transition temperature of at least <NUM>,
b) an elastomeric phase of macromolecular sequences having a flexible nature with a glass transition temperature of less than <NUM>, and
c) a fluorescent dye;
wherein said elastomeric phase of macromolecular sequences with the flexible nature forming the elastomeric phase is part of a block copolymer with at least one block having a glass transition temperature of less than <NUM>;
said elastomeric phase of macromolecular sequences with the flexible nature being selected from a thermoplastic block copolymer, said thermoplastic block copolymer comprising at least one block which is an acrylic block;
and wherein said acrylic block copolymer has a general formula (A)nB in which:
• n is an integer of greater than or equal to <NUM>,
• A is: an acrylic or methacrylic homo- or copolymer having a Tg of greater than <NUM>, or polystyrene, or an acrylic/styrene or methacrylic/styrene copolymer;
• B is an acrylic or methacrylic homo- or copolymer having a Tg of less than <NUM>;
and wherein the polymeric phase having a glass transition temperature of at least <NUM> is either the block A of said thermoplastic acrylic block copolymer or another thermoplastic polymer P1; or a mixture of both.