METHOD FOR PRODUCING A PHOTOLUMINESCENT COMPOSITION, PRESERVED PHOTOLUMINESCENT COMPOSITION AND METHOD FOR MAINTAINING THE LUMINANCE

Description

[0001] The invention relates to a method for manufacturing a photoluminescent composition and the photoluminescent composition obtained from the implementation of said method. The invention also relates to a method for maintaining the luminance of such a composition.

[0002] Photoluminescent coatings are known, in particular those intended to be used to make products coated with them emit light after being exposed to it, naturally, without any energy source.

[0003] This phenomenon of photoluminescence is very well known and many mineral compounds have this property of absorption in one wavelength and restitution in another wavelength.

[0004] Photoluminescent particles are based on an inorganic matrix and a doping ion. Among the inorganic matrices, we have, for example: MAl 2 O 4 (M = Ca, Sr, Ba, Mg), MSiO 3 (M = Cd, Ca, Sr, Ba, Mg), MS (M = Ca, Zn), , MSnO 4 (M = Mg, Ca).

[0005] Among the rare earth ions, we have for example: Ln 3+< : Eu 3+< , Eu 2+< , Ce 3+< , Tb 3+< , Sm 3+< , Pr 3+< , Dy 3+< , Er 3+< , Tm 3+< , Nd 3+< , or the ions of a transition metal like V 3+< , Cu 2+< , Mn 2+< , Ti 4+< , Sn 2+< , Co 2+< , Bi 3+< , Pb 2+< to name just a few.

[0006] There are many applications, for example, in horizontal and vertical signage. Rather than illuminating roads with information signals and consuming energy, it would be more rational and environmentally friendly to have markings that can be seen even in the absence of lighting.

[0007] This would allow users to be guided in a completely appropriate manner. However, not only must the photoluminescence density be sufficient, but the effect must also last throughout the absence of natural or artificial light.

[0008] The aim of these compositions is to generate as high a photoluminescent power as possible and as long-lasting as possible.

[0009] The ratio of photoluminescent compounds to the matrix that receives them must then be improved.

[0010] The known compositions comprise a matrix, generally colorless, to which is added a set of inorganic fillers which aim to make said composition opacifying in order to mask the support receiving said composition.

[0011] In fact, for the photoluminescent effect to be high, it is necessary to increase the density on the one hand and mask the support on the other.

[0012] The fillers required to make the composition opacifying have the disadvantage of representing a percentage of up to 50% of the matrix.

[0013] Also the percentage of photoluminescent mineral compounds necessarily remains low.

[0014] Mechanical wear can also be a real problem because the compositions, once placed on a support, for example road paint, undergo mechanical wear by the passage of vehicles, which removes part of the material and therefore reduces the density of photoluminescent compounds which was already relatively low due to the high rate of charges.

[0015] Document WO2016027027 describes a method for manufacturing a photoluminescent material comprising the combination of two substances having well-defined particle sizes. However, the described method does not make it possible to obtain a photoluminescent composition having an improved density and therefore an improved coverage while avoiding masking the photoluminescent compounds.

[0016] The invention therefore aims to overcome the problems of the compositions of the prior art and to propose a method for producing a composition comprising high-density photoluminescent compounds, therefore generating strong photoluminescence and a composition having high coverage, with a low level of inorganic fillers, this for a long period due to the possibility of capturing high energy and restoring this energy for a long period.

[0017] The present invention also relates to a method for maintaining the luminance of this composition above a given threshold.

[0018] For this purpose, the method for producing a photoluminescent composition, in particular from granular PH photoluminescent compounds, chosen from inorganic matrices doped with at least one ion, said photoluminescent composition being intended to be introduced with at least one inorganic filler into a transparent matrix, is characterized in that it comprises a production step which consists of: Choose a first photoluminescent compound PH1 with a particle size range comprising a peak centered on a value P1 corresponding to a particle diameter D1, Choose at least a second photoluminescent compound PH2 with a particle size range comprising a peak centered on a value P2 corresponding to a particle diameter D2, Choose the diameter D2 equal to the maximum measurement M1 of the volume space V1 left free at the center of the square arrangement of four juxtaposed particles of diameter D1 calculated by the formula D 2 = 2 ∗ D 1 2 − 2 ∗ D 1 / 2 .

[0019] More particularly, the method for producing a photoluminescent composition is characterized in that at least one inorganic filler is associated, the particle size range of this at least one filler being chosen with a peak centered on a PC value corresponding to a diameter smaller than that of D2.

[0020] According to the invention, in the method, the matrices of the photoluminescent compounds are chosen from the following families: MAl2O4 (M=Ca, Sr, Ba, Mg), MSiO3 (M=Cd, Ca, Sr, Ba, Mg), MS (M=Ca, Zn), , MSnO4 (M=Mg, Ca) and the doping ions from the rare earth ions: Ln3+: Eu3+, Eu2+, Ce3+, Tb3+, Sm3+, Pr3+, Dy3+, Er3+, Tm3+, Nd3+, or from the ions of a transition metal such as V3+, Cu2+, Mn2+, Ti4+, Sn2+, Co2+, Bi3+, Pb2+.

[0021] Opacifying fillers are selected from titanium oxide, zinc oxide, barium sulfate, calcium carbonate, zirconia or a mixture thereof.

[0022] The invention also covers a photoluminescent composition obtained by the method which comprises: a first photoluminescent compound PH1 with a particle size range comprising a peak centered on a value P1 corresponding to a particle diameter D1, at least one second photoluminescent compound PH2 with a particle size range comprising a peak centered on a value P2 corresponding to a particle diameter D2, the diameter D2 being equal to the maximum measurement M1 of the volume space V1 left free at the center of the square arrangement of four juxtaposed particles of diameter D1 calculated by the formula D 2 = 2 ∗ D 1 2 − 2 ∗ D 1 / 2 . the matrices of the photoluminescent compounds being chosen from the following families: MAl2O4 (M=Ca, Sr, Ba, Mg), MSiO3 (M=Cd, Ca, Sr, Ba, Mg), MS (M=Ca, Zn), , MSnO4 (M=Mg, Ca) and the doping ions from the rare earth ions: Ln3+: Eu3+, Eu2+, Ce3+, Tb3+, Sm3+, Pr3+, Dy3+, Er3+, Tm3+, Nd3+, or from the ions of a transition metal such as V3+, Cu2+, Mn2+, Ti4+, Sn2+, Co2+, Bi3+, Pb2+, and at least one opacifying filler.

[0023] In this composition, the opacifying fillers are chosen from titanium oxides, zinc oxide, barium sulfate, calcium carbonate, zirconia or a mixture thereof.

[0024] The invention also relates to a photoluminescent coating, comprising such a composition mentioned above and embedded in a transparent resin.

[0025] This transparent resin is chosen from the following families: polyurethanes, acrylics, epoxies, alkyds.

[0026] The invention covers photoluminescent applications and in particular the use of a coating for producing a paint for road signs or for producing an ink for printing on paper, polymer film or fabric.

[0027] The invention also relates to the additive masterbatch obtained from such a composition which can be used in injection or extrusion of polymer matrices with a view to producing photoluminescent products.

[0028] The present invention is now described with the aid of examples which are solely illustrative and in no way limitative of the scope of the invention, and from the attached illustrations, in which: [ Fig. 1 ] represents a view of a theoretical particle size distribution of the process according to the present invention, considering a 3-particle structure PH1, PH2 and PH3. [ Fig. 2A ] represents a diagram illustrating the theoretical geometric distribution of photoluminescent materials according to the prior art in the case of four (4) PH1 particles, within a coating layer with said composition on a support. [ Fig. 2B ] represents a diagram illustrating the theoretical geometric distribution of an elementary module, of photoluminescent materials according to the method of the invention in the case of two particles PH1 and PH2, within a coating layer with said composition on a support. [ Fig. 3 ] represents a comparison of the luminescence at 10 minutes of a composition according to the present invention obtained by the process according to the present invention with two particles PH1 and PH2 to two commercial paints with the same pigment content and the same thickness on two different white and black backgrounds. [ Fig. 4 ] represents the comparison of the luminescence at 10 minutes of a composition according to the present invention obtained by the process according to the present invention with two types of particles PH1 and PH2 to a commercial ink with the same pigment content and the same thickness. [ Fig. 5 ] represents the evolution of the coverage parameter of a photoluminescent varnish comprising three types of particles PH1, PH2 and PH3, in the form of a ternary diagram. [ Fig. 6 ] represents the same ternary diagram with luminance values ​​10 minutes after excitation. [ Fig. 7 ] represents a theoretical luminance maintenance diagram. [ Fig. 8 ] represents an example of maintaining the luminance of an ink.

[0029] The method according to the present invention consists in establishing a particle size distribution comprising at least two different particle size ranges of photoluminescent compounds PH1 and PH2. On the figure 1 , an example distribution is shown with three ranges of photoluminescent compounds PH1, PH2 and PH3.

[0030] Each range of photoluminescent compounds has a peak of granulometry P1, P2 and P3, these peaks are complementary.

[0031] Peak P1 corresponds to particles with a diameter D1 and peak P2 corresponds to a diameter D2 and peak P3 corresponds to a diameter D3.

[0032] The diameter D2 is chosen to correspond substantially to the maximum measurement M1 of the volume space V1 released by the presence of at least four juxtaposed particles PH1 of diameter D1.

[0033] The following example has four PH1 particles of diameter D1 juxtaposed.

[0034] On the figure 2A , we see that in the case of a theoretical module of four particles, free spaces are released in which the charges are housed in the compositions of the prior art, charges not shown.

[0035] According to the method of the present invention, a combination of two photoluminescent particles PH1 and PH2 is chosen, the diameter D2 of the PH2 particles corresponding to the diameter left free in the center by the arrangement in a square and in contact of the four juxtaposed PH1 particles of diameter D1 calculated by the formula D 2 = 2 ∗ D 1 2 − 2 ∗ D 1 / 2 .

[0036] On the figure 2B , we have represented a theoretical module with four PH1 particles, 1 PH2 particle, 4 halves of PH2 particles and four quarters of PH2 particles. The notions of half and quarter are theoretical with regard to the module considered.

[0037] The volumetric filling is therefore, for a module, 4 photoluminescent particles PH1 and 4 photoluminescent particles PH2 so as to give the whole the best thermodynamically stable compactness.

[0038] This significantly increases the volume of photoluminescent material per unit volume.

[0039] By "complementary" we mean that the photoluminescent compounds PH1 and PH2 are chosen to limit the free inter-particle volumes of one by the other and are from the same family.

[0040] In practice, the process involves screening the ground photoluminescent compounds in order to benefit from precise, narrowest granulometric ranges.

[0041] Depending on the process, the photoluminescent compounds are chosen in diameter and volume percentage of the mixture to ensure optimal filling.

[0042] The at least two photoluminescent compounds are mixed and then integrated with at least one opacifying filler into at least one transparent matrix to produce a photoluminescent composition to be coated.

[0043] Depending on the nature of this matrix, the coating is considered a paint or an ink.

[0044] Paint, in solvent or aqueous phase, is understood to mean a liquid or powder product containing pigments, applied to a surface, associated with protective, decorative or technical properties. The transparent resin for a paint in which the composition obtained by the process and at least one opacifying filler are incorporated, is chosen, in a non-limiting manner, from the following families: polyurethanes, acrylics, epoxies, alkyds.

[0045] The term “ink”, polymerizing under ultraviolet light, in solvent or aqueous phase, means a liquid product for marking a paper or textile support, or a polymer film for example. The transparent resin for an ink in which the composition obtained by the process and at least one opacifying filler are incorporated is chosen, for example and in a non-limiting manner, from the following families: epoxy, acrylic, solvent naphtha, nitrocellulose, alkyds, polyurethanes, polyamides, ketones, polyesters.

[0046] The opacifying inorganic filler is chosen, for example and in a non-limiting manner, from the following families or a mixture thereof: titanium oxide, zinc oxide, barium sulfate, calcium carbonate, zirconia.

[0047] The transparent resin in which the composition obtained by the process and at least one opacifying filler are incorporated is chosen, for example and in a non-limiting manner, from the following families: polyurethanes, acrylics, epoxies, alkyds.

[0048] The geometric arrangement is obtained by mixing the particles of at least two compounds PH1 and PH2 and at least one charge associated with the particles of photoluminescent compounds. This geometry, due to the distribution retained and the percentage of each of the photoluminescent compounds chosen, is unique since only this formation is thermodynamically stable, corresponding to maximum compactness.

[0049] The fillers are also chosen from a particle size profile complementary to the particle size profiles of the photoluminescent compounds. The choice of the particle size peak is dictated so that the fillers fill the inter-particle voids generated by the at least two photoluminescent compounds used. The filler mainly comprises particles with a diameter smaller than that of the smallest of the photoluminescent particles in order not to interfere or at least to limit interference.

[0050] It is noted that the architecture of the particles responds to a thermodynamic equilibrium and in the case of particles of a single diameter, the particles are positioned in a staggered manner to limit the void volumes and offer the best compactness. On the other hand, when there are at least two types of particles, the thermodynamic equilibrium leads to a geometry as drawn, namely PH1 particles aligned perpendicularly and PH2 particles arranged in the volumes left free because this is the best possible compactness and the architecture is thus stable. In addition, in the case of the present invention, the particle size of the PH2 has been chosen to be adapted to the inter PH1 volume intended to collect said PH2 particles. This makes it possible to improve the density and therefore the coverage while avoiding masking the photoluminescent compounds. The segregation phenomena of the PH1, PH2 particles .....PHn of the same family are impossible when the particles are of the same nature and such aggregations would not be stable. On one side PH1, on the other PH2 for example is not thermodynamically possible.

[0051] This results in very significant photoluminescence gains. Thus, the figure 3 shows on the left graph the results obtained on a white background and on the right graph the results obtained on a black background, with a distribution of 3 types of particles PH1, PH2 and PH3 having diameter peaks at D1, D2 and D3 prepared according to the method of the present invention, in proportions of P1, P2 and P3.

[0052] The comparison is made using products marketed under the trade names Elite paints from the Oré Peinture company and Axion paints from the Maestria company.

[0053] These results concern the luminescence at 10 minutes (Y 600) after excitation (15 minutes under D65 X-Rite lamp, 1500 lux) at the same rate of insertion of photoluminescent pigments in the 3 tests, for a thickness of 500µm on a white background.

[0054] In fact, as there is no photoluminescent paint, the comparative tests were carried out with commercial road paints to each of which the same quantity of photoluminescent pigments was added but without choice of distribution, in this case a photoluminescent pigment marketed under the name JPA-388 from the company FOSHAN JULIANG Photoluminescent Pigments.

[0055] The luminescence values, expressed in milli candela, at 10 minutes on a white background, for the composition according to the present invention produced from the process introduced into a transparent resin matrix according to the invention and therefore of choice of particle size distributions PH1 / PH2 / PH3, are: 662 mCd / m 2< for PH1 / PH2 / PH3 26 mCd / m 2< for ELITE, and 18 mCd / m 2< for AXION.

[0056] Luminescence values, expressed in milli candela, at 10 minutes (Y 600) after excitation (15 minutes under D65 X-Rite lamp, 1500 lux) at the same rate of insertion of photoluminescent pigments in the 3 tests, for a thickness of 500µm, on a black background.

[0057] For the composition according to the present invention produced from the process according to the invention and therefore the choice of particle size distributions PH1 / PH2 / PH3, and the two commercial products compared, are: 379 mCd / m 2< for PH1 / PH2 / PH3 14 mCd / m 2< for ELITE, and 14 mCd / m 2< for AXION.

[0058] Similarly, comparative tests are conducted for inks by comparing a commercial ink, for example a white ink reference TG103 from the company VFP Inks and an ink produced with a composition of photoluminescent pigments according to the process of the present invention.

[0059] The insertion rate of photoluminescent pigments in the 2 tests is identical.

[0060] The luminescence values, expressed in milli candela, at 10 minutes on a white background, for the composition according to the present invention produced from the process according to the invention and therefore from the choice of particle size distributions PH1PH2PH3 in a transparent resin matrix, and those of the compared product are: 49 mCd / m 2< for PH1 / PH2 / PH3 7 mCd / m 2< for TG103.

[0061] The luminescence values, expressed in milli candela, at 10 minutes on a black background, for the composition according to the present invention produced from the process according to the invention and therefore from the choice of PH2PH3 particle size distributions, and those of the compared product are: 10 mCd / m 2< for PH2 / PH3 3 mCd / m 2< for TG103.

[0062] The synergistic effect of a composition according to the present invention from a ternary with photoluminescent particles PH1, PH2 and PH3 was also tested.

[0063] We see that the coverage varies and increases when we choose a proportion of 1 x PH of larger diameter, 2 x PH2 of intermediate diameter and 3 x PH3 of small diameter.

[0064] By large diameter we mean, for example, 100, which leads to an intermediate diameter to fit into the freed volumes of: D 2 = 2 xD 1 √ 2 − 2 xD 1 / 2 D 2 = 2 x 100 √ 2 − 2 x 100 / 2 D 2 = 40

[0065] The same applies to photoluminescent particles of diameter D3 which lodge in the spaces freed by photoluminescent particles of diameters D1 and D2, the diameter of which D3 is therefore less than that of D2 which itself was less than D1.

[0066] Thus, the coverage of a composition established according to the method of the present invention results in having particles of three different diameters D1, D2 and D3 with covering powers of: PH1 coverage 68.87% when used alone PH2 coverage 72.93% when used alone PH3 coverage 76% when used alone

[0067] In fact, it is found that a mixture according to the process of the present invention with a proportion of 1 x PH of larger diameter and greater coverage, 2 x PH2 of intermediate diameter and lower coverage and 3 x PH3 of small diameter and even lower coverage, a coverage of the composition according to the invention of 85.87% is obtained, higher than that of a composition of particles with a mono distribution, centered on a diameter D1 or D2 or D3.

[0068] The percentages are expressed in number of particles. We can also see on the ternary of the figure 6 that each of the chosen compounds PH1, PH2 and PH3 respectively has a luminance value at 10 minutes after excitation for 15 minutes under a D65 X-Rite lamp, 1500 lux, of 323 mCd / m 2< , 358 mCd / m 2< and 362 mCd / m 2< . It is noted that the ternary PH1PH2PH3, D1, D2 and D3 has a luminance of 379 mCd / m 2< , higher than the luminance of each of them.

[0069] The mixture of photoluminescent particles, fillers and at least one transparent resin makes it possible to obtain an additive masterbatch which can be used in injection or extrusion of polymer matrices in order to produce photoluminescent products.

[0070] According to the method of the present invention, a method is provided for maintaining the luminance above a given threshold Z. To this end, the method consists of regularly exciting the composition according to the present invention once affixed to a support, before the luminance value reaches a value lower than said threshold Z, on the figure 7 , after a duration Y. Thus, when a composition according to the present invention is excited during period X, the luminance rate is at its maximum dotted line then over time, the relaxation leads to a loss of luminance and when the luminance reaches a threshold value Z, the method provides for a re-excitation of the composition up to the maximum luminance. Thus by successive excitations, it is possible to maintain the luminance between the threshold Z and the maximum luminance. An indication of the durations is for example a re-excitation duration of 3 min and a relaxation of 60 min.

[0071] The graph of the figure 8, concerning an acrylic resin-based ink and a composition according to the present invention, real values ​​close to the theory are obtained, the luminance remaining in the luminance range fixed at approximately 8 mCd / m 2 < . Thus, it is possible to keep a product or signage illuminated for a long period with excitation of a very limited duration of 3 min in this case. The excitation and re-excitations can be obtained for concrete projects such as road markings by any means which may be public lighting, specific lighting with controlled duration and / or intensity.

[0072] The advantage of a composition according to the present invention is to remain effective with a sufficient luminance threshold for very long periods, including if there is passage and the coating on the support erodes. The composition according to the invention making it possible to confer the same luminance in the mass is also ready to receive a sufficient quantity of energy during the excitation phase, to restore it during the relaxation phase. It is understood that what is valid for the composition as a whole is valid for the coating made from said composition.

Claims

1. Method for producing a photoluminescent composition, in particular from granular PH photoluminescent compounds selected from inorganic matrices doped with at least one ion, said photoluminescent composition being intended to be introduced with at least one inorganic filler into a transparent matrix, characterized in that it comprises a step for producing said composition which consists in: - Selecting a first photoluminescent compound PH1 with a particle size range comprising a peak centered on a value P1 corresponding to a particle diameter D1, - Selecting at least one second photoluminescent compound PH2 with a particle size range comprising a peak centered on a value P2 corresponding to a particle diameter D2, - Selecting the diameter D2 equal to the maximum measurement M1 of the volumetric space V1 left free at the center of the square arrangement of four juxtaposed particles of diameter D1 calculated by the formula D2 = [2*D1√2-(2*D1) / 2].

2. Method for producing a photoluminescent composition according to claim 1, characterized in that at least one filler is associated therewith, the particle size range of this at least one inorganic filler being selected with a peak centered on a value PC corresponding to a diameter D smaller than the smallest diameter D1, D2 of the at least one photoluminescent compound PH1, PH2.

3. Method for producing a photoluminescent composition according to claim 1 or 2, characterized in that the matrices of photoluminescent compounds are selected from the following families: MAl2O4 (M=Ca, Sr, Ba, Mg), MSiO3 (M=Cd, Ca, Sr, Ba, Mg), MS (M=Ca, Zn), MSnO4 (M=Mg, Ca) and the dopant ions from among the rare earth ions: Ln3+: Eu3+, Eu2+, Ce3+, Tb3+, Sm3+, Pr3+, Dy3+, Er3+, Tm3+, Nd3+, or from the ions of a transition metal such as V3+, Cu2+, Mn2+, Ti4+, Sn2+, Co2+, Bi3+, Pb2+.

4. Method for producing a photoluminescent composition according to any one of the preceding claims, characterized in that the filler is an opacifying filler and this filler is selected from titanium oxide, zinc oxide, barium sulfate, calcium carbonate, zirconia or a mixture thereof5. Photoluminescent composition obtained by the method according to any one of the preceding claims, characterized in that it comprises: - a first photoluminescent compound PH1 with a particle size range comprising a peak centered on a value P1 corresponding to a particle diameter D1, - at least one second photoluminescent compound PH2 with a particle size range comprising a peak centered on a value P2 corresponding to a particle diameter D2, the diameter D2 equal to the maximum measurement M1 of the volumetric space V1 left free at the center of the square arrangement of four juxtaposed particles of diameter D1 calculated by the formula D2=[2*D1√2-(2*D1) / 2]. - the matrices of photoluminescent compounds being selected from the following families: MAl2O4 (M=Ca, Sr, Ba, Mg), MSiO3 (M=Cd, Ca, Sr, Ba, Mg), MS (M=Ca, Zn), MSnO4 (M=Mg, Ca) and the dopant ions from among the rare earth ions: Ln3+: Eu3+, Eu2+, Ce3+, Tb3+, Sm3+, Pr3+, Dy3+, Er3+, Tm3+, Nd3+, or from the ions of a transition metal such as V3+, Cu2+, Mn2+, Ti4+, Sn2+, Co2+, Bi3+, Pb2+, and - at least one opacifying filler.

6. Photoluminescent composition according to claim 5, characterized in that the fillers are selected from titanium oxide, zinc oxide, barium sulfate, calcium carbonate, zirconia or a mixture thereof.

7. Photoluminescent coating, characterized in that it comprises a composition according to one of claims 5 or 6, embedded in a transparent resin.

8. Photoluminescent coating according to claim 7, characterized in that the transparent resin is selected from the following families: polyurethanes, acrylics, epoxies, alkyds.

9. Use of a coating according to claim 7 or 8 for producing a paint for road signs.

10. Use of a coating according to claim 7 or 8 for producing an ink for printing on paper, polymer film or fabric.

11. Additive masterbatch obtained from a composition according to claim 5 or 6, for use in the injection or extrusion of polymeric matrices in order to produce photoluminescent products.