Dark color photoluminescent materials

Abstract

The present invention relates to a photoluminescent material comprising, by weight, 19.8% to 54.8% of a polymer matrix, 45% to 80% of a photoluminescent compound, 0.2% to 5% of a first dye system and optionally 0% to 1% of porous silica, and a second dye system and an additive wherein the total percentage of the second dye system and the additive is 0% to 15%, the first dye system comprises one or more dyes selected from a three-color pigment formed from a green pigment, a blue pigment, and a red pigment, and a synthetic black pigment. The invention also relates to an article coated with the photoluminescent material or an article prepared as a whole from the photoluminescent material.

Description

Technical Field

[0001] The present invention relates to dark photoluminescent materials having optimized luminescent properties. Background Art

[0002] The prior art discloses phosphorescent materials made from mixtures of transparent or translucent materials and photoluminescent pigments, which are prepared from inorganic oxides doped with rare earth elements. Examples include mixtures of borosilicate and 50% strontium aluminate doped with europium and dysprosium (Eu 2+ , Dy 3+ :SrAl2O4), or mixtures of acrylic resins and 50% strontium aluminate doped with europium and dysprosium. The light decay of these materials is exponential at the beginning. If we start with a brightness of several tens of Cd / m 2 and place the material in the dark after saturating it with light energy, the brightness after 10 minutes in the dark will be less than 1 Cd / m 2 . Then, the light decay slowly approaches an asymptote at a few mCd / m 2 , which explains the reason why these materials can maintain visible luminescence persistence in the dark for up to 12 hours. For good passive readability of diving devices, these luminescent materials are necessary, so progress in luminescent properties is still being sought.

[0003] For aesthetic reasons, these photoluminescent materials can be colored using a dye system, which is a mixture of pigments and additives.

[0004] It has been noted that compounds used in photoluminescent materials, including coloring pigments, have a quenching effect on luminescent properties, and the brightness of phosphorescent materials is the result of physicochemical interactions between various compounds in the photoluminescent materials.

[0005] Therefore, it is difficult to optimize coloring and luminescent properties simultaneously. For black and generally dark colors, various carbon blacks were tested. It was found that these carbon blacks absorb too much in the absorption and emission ranges of phosphorescent pigments, which affects the luminescent properties of the materials. Therefore, optimization between color and photoluminescence must always be sought. Summary of the Invention

[0006] The present invention includes novel formulations that enable the attainment of a beautiful black color in daylight and generally beautiful dark colors in daylight, while simultaneously having excellent luminescent properties.

[0007] For this purpose, the present invention proposes adding to the formulation a three-color pigment mixture consisting of red, green and blue, or a synthetic black pigment of the C.I. Solvent Black 27, Brilliant Black BN or perylene black type, or a combination of said three-color pigment and said synthetic black pigment. The formulation may contain the three colors to obtain a dark color, which is then adjusted by adding a synthetic black pigment. Optionally, the color may be adjusted by adding a small amount of carbon black. In another embodiment, the formulation contains only the synthetic black pigment and optionally a small amount of carbon black to obtain a black color with excellent phosphorescence intensity.

[0008] Optionally, the photoluminescent material further contains porous silica derived from algae to improve the luminescence performance. The porous silica is from diatom skeletons. They are microalgae, which are single-celled organisms with silica skeletons. More specifically, according to the latest biological research, diatoms, as a type of single-celled algae that make up plankton, are composed of silica nanocells that are very effective in absorbing sunlight, even in the dark depths of the ocean, so they can effectively carry out photosynthesis. Adding a limited percentage of porous silica to the photoluminescent material can improve the luminescence performance, and the content is less than or equal to 1% by mass.

[0009] More specifically, the present invention relates to a photoluminescent material which, by weight, comprises 19.8% to 54.8% of a polymer matrix, 45% to 80% of a photoluminescent compound, 0.2% to 5% of a first dye system and optionally 0% to 1% of porous silica, as well as a second dye system and additives, wherein the total percentage of the second dye system and additives is 0% to 15%, and the first dye system comprises one or more dyes selected from the three-color pigments formed by green pigment, blue pigment and red pigment, and synthetic black pigments.

[0010] The present invention also relates to an article integrally prepared from the photoluminescent material, or an article coated with the photoluminescent material. Detailed Description

[0011] The present invention relates to a dark photoluminescent material which can be used to integrally prepare articles or to coat articles. The articles can be, for example, watch parts. More specifically, the articles can be external parts selected from the non-limiting list including watch middle parts, back covers, bezels, crowns, push-pieces, bracelet links, bracelets, tongue buckles, clasps, dials, flanges, date discs, hands and dial graduations.

[0012] The photoluminescent material comprises (consists of) a polymer matrix, a photoluminescent compound, a first dye system and optionally porous silica, additives and a second dye system.

[0013] The first dye system, which constitutes a more specific subject of the present invention, comprises one or more dyes selected from the group consisting of trichromatic pigments formed from red, green and blue primary pigments and synthetic black pigments, the synthetic black pigments preferably being Solvent Black 27, perylene black and / or Brilliant Black BN. The first dye system is present in a weight percentage of from 0.2% to 5%, preferably from 0.3% to 4%, more preferably from 0.4% to 2%.

[0014] For example, the red primary pigment can be magenta (a varnish pigment derived from carmine), azo, quinacridone or perylene type. The green primary pigment can be phthalocyanine or naphthol type, and the blue primary pigment can be anthraquinone, phthalocyanine or perylene type. Solvent Black 27 has the formula C 17 H 13 N3O4Cr 1 / 2 . For example, it is commercially available under the trade name Black H. Brilliant Black BN, also known as Black PN, is a dye of the azo family and has the formula C 28 H 17 N5Na4O 14 S4. It can be obtained, for example, from Sensient Cosmetic Technologies under the trade name NOIR BRILLANT BN 80% E151. Those skilled in the art can also use perylene black.

[0015] According to a first alternative embodiment, the first dye system consists of only three-color pigments. For this alternative embodiment, the percentage of the three-color pigments, based on the total weight of the photoluminescent material, is from 0.5% to 4%, preferably from 0.7% to 2%. Preferably, the three pigments are present in the same percentage. For example, if 1.5% of the three-color pigments are added, the addition ratio of each pigment is 0.5% of the total weight. This equal ratio can be ignored when the usage ratio of each pigment is from 20% to 40%. According to a second alternative embodiment, the first dye system consists of three-color pigments on the one hand and synthetic black pigments on the other hand, wherein the content of the three-color pigments is from 0.2% to 3%, preferably from 0.4% to 1.5%, more preferably from 0.4% to 1% based on the total weight of the photoluminescent material, and the content of the synthetic black pigments is from 0.01% to 1%, preferably from 0.02% to 0.5%, more preferably from 0.02% to 0.2% based on the total weight of the photoluminescent material. According to a third alternative embodiment, the first dye system consists of only synthetic black pigments, and the content of the synthetic black pigments is from 0.2% to 2%, preferably from 0.3% to 1.5%, more preferably from 0.3% to 1% based on the total weight of the photoluminescent material.

[0016] The polymer matrix is present in a weight percentage of from 19.8% to 54.8%, preferably from 29.7% to 49.7%, more preferably from 34.6% to 44.6%. It should be noted that the upper limit of the polymer matrix is calculated for the photoluminescent material without porous silica, without the second dye system, and without additives. In the presence of any of these compounds, the upper limit will be reduced accordingly so that the total amount of the compounds in the photoluminescent material does not exceed 100%. As for the polymer matrix, it can be any polymer that is transparent or translucent in the visible range. For example, it can be one or more of the following polymers: resins from the acrylic family, the polyamide family, the polyolefin family, the epoxy family, the polyurethane family, the fluorinated elastomer family, and silicone.

[0017] The photoluminescent compound is present in a weight percentage of from 45% to 80%, preferably from 50% to 70%, more preferably from 55% to 65%. The photoluminescent compound can consist of pigments or pigments encapsulated in a transparent shell. The pigment is preferably a rare earth element-doped alkaline earth metal aluminate derivative. More specifically, the pigment can be strontium aluminate doped with europium and dysprosium, which has the formula Sr(x)Al(y)O(z):Eu 2+ ,Dy 3+ . In particular, it can be Sr4Al 14 O 25 :Eu 2+ ,Dy 3+ or SrAl2O4:Eu 2+ ,Dy3 + , optionally both of which are present in the photoluminescent compound. Advantageously, the pigments can have different particle sizes to allow for an optimal distribution of the pigments within the volume and to avoid free space. The presence of different particle sizes within the volume also enables the incorporation of small and large particles, where the small particles form shallow traps responsible for high light intensity in the short term and the large particles form deeper traps responsible for the remaining light intensity in the long term. For example, the pigments can have a first particle size range with a diameter D1 of about 500 nm to 10 μm, desirably 500 nm to 5 μm, and a second particle size range with a diameter D2 of about 10 μm to 500 μm, desirably 10 μm to 20 μm, the particle sizes being measured by laser particle size analysis according to ISO 13320:2020, optionally equipped with SEM analysis using secondary electron imaging. It should be noted that more than two particle size fractions can be screened and then combined. For example, there can be a first fraction of 500 nm to 5 μm at 20 wt%, a second fraction of 5 μm to 20 μm at 60 wt%, and a third fraction of 20 μm to 50 μm at 20 wt%.

[0018] The pigments can optionally be encapsulated in a transparent organic or inorganic shell. The organic shell can generally be selected from those polymers mentioned with respect to the polymer matrix. The inorganic shell can be, for example, a silica (SiO2) shell, which can be obtained, for example, by the sol-gel method. Other examples of inorganic shells include zirconia (ZrO2) and alumina (Al2O3), etc.

[0019] The photoluminescent material optionally further contains a total of 0 wt% to 15 wt%, preferably 0 wt% to 5 wt%, of a second dye system and additives. Advantageously, the material contains 0.5 wt% to 5 wt% of the second dye system and additives. The second dye system preferably contains organic dyes that do not absorb within the emission wavelength range of the photoluminescent pigment. These organic dyes can be fluorescent pigments or dyes that absorb more in the UV range and emit in the visible spectrum. Examples include organic fluorescent pigments or dyes, such as those from or . They can also be translucent pigments or dyes that have low absorption in the emission wavelength of the phosphorescent pigment. Examples include translucent pigments or dyes from Clariant. The second dye system can also include carbon black to adjust the dark color. The percentage of carbon black is 0% to 1%, preferably not more than 0.5%, or even not more than 0.3%. If carbon black is present, its lower limit is 0.01%. Thus, the percentage of carbon black is 0.01% to 1%, preferably 0.01% to 0.5%, more preferably 0.01% to 0.3%.

[0020] Other additives can be added, such as metallic and pearlescent effect pigments, UV-resistant additives for protecting the polymer matrix, dispersants such as silanes for promoting the dispersion of additives, and silica-based nanofillers for adapting the viscosity parameters of the mixture, etc.

[0021] Optionally, the photoluminescent material can contain porous silica derived from diatom skeletons. Generally, the average pore diameter can be about 500 nm. Optionally, it can be synthetic porous silica. Regarding synthetic silica, the pores generally have an average diameter of 0.1 μm to 3 μm. The porous silica is present in a weight percentage of 0% to 1%, preferably 0.01% to 1%, more preferably 0.07% to 0.3%, and even more preferably 0.09% to 0.2%.

[0022] The method for manufacturing an article integrally from a photoluminescent material includes mixing one or more polymers for forming a polymer matrix with a preferred dispersant. This initial mixture is mixed with a photoluminescent pigment, which can optionally have been pre-encapsulated. Then a first dye system and any second dye system, additives, and porous silica are added to this second mixture. These mixtures can be prepared from a liquid resin using an accelerating mixer or a paddle mixer. The resulting mixture can then be extrusion molded. These mixtures can also be prepared in a twin-screw extruder or a high-speed mixer for producing thermoplastic mixtures and transformed into pellets, which can be reused for injection molding.

[0023] The method for manufacturing an article coated with a photoluminescent material includes depositing a coating on a substrate, which is carried out using techniques such as screen printing, pad printing, or spraying.

[0024] The test for preparing a sample integrally with a photoluminescent material is carried out as follows: A dye system containing a trichromatic pigment and Solvent Black 27 is added to an epoxy resin, where the filling content of the photoluminescent pigment Eu 2+ , Dy 3+ :SrAl2O3 is 60% by weight. The weight percentage of the trichromatic pigment is 0.6%, with the same distribution ratio for each color; the weight percentage of Solvent Black 27 is 0.05%. Tests are also carried out using the same base material and Solvent Black 27 as the dye system, where the percentage of Solvent Black 27 is 0.4% of the total weight. Tests are also carried out using the same base material and the trichromatic pigment as the dye system, where the total weight percentage of the trichromatic pigment is 1.5% based on the total weight, and the percentage of each color is 0.5%.

[0025] Tests are also carried out using an additional 0.2% porous silica.

[0026] These samples were observed under a D65 light source lamp box. At the same time, comparative tests were carried out with various black pigments, including carbon blacks with different particle sizes and structures, or inorganic substances such as iron oxide III (Fe3O4), where the same base materials were used.

[0027] These materials were shaped by vacuum casting.

[0028] When inorganic oxides were used, the luminescent materials quenched quickly. When carbon blacks were used, the color was very dark, but when carbon blacks were used alone, the loss of brightness was too large. When tests were carried out with a single three-color pigment, a single solvent black 27, and a combination of the two, satisfactory colors were obtained under sunlight, and the luminescence performance was improved by 15%. Tests using porous silica showed a 20% improvement in luminescence performance after 10 minutes, where the luminescence performance was detected according to ISO 17514-2003.

Claims

1. A photoluminescent material comprising by weight 19.8% to 54.8% of a polymer matrix, 45% to 80% of a photoluminescent compound, 0.2% to 5% of a first dye system and optionally 0% to 1% of porous silica, and a second dye system and additives, wherein the total percentage of the second dye system and the additives is 0% to 15%, the first dye system comprising one or more dyes selected from trichromatic pigments formed by a green pigment, a blue pigment and a red pigment and a synthetic black pigment.

2. The photoluminescent material according to claim 1, characterized in that The synthetic black pigment is solvent black 27, brilliant black BN, perylene black or a combination of these three pigments.

3. The photoluminescent material according to claim 1 or 2, characterized in that The polymer matrix is ​​present at a percentage of 29.7% to 49.7%, the photoluminescent compound is present at a percentage of 50% to 70%, and the first dye system is present at a percentage of 0.3% to 4%.

4. The photoluminescent material according to any one of the preceding claims, characterized in that The polymer matrix is ​​present at a percentage of 34.6% to 44.6%, the photoluminescent compound is present at a percentage of 55% to 65%, and the first dye system is present at a percentage of 0.4% to 2%.

5. The photoluminescent material according to any one of the preceding claims, characterized in that The first dye system consists of 0.5 to 4% by weight, preferably 0.7 to 2% by weight, of trichromatic pigments.

6. The photoluminescent material according to any one of claims 1 to 4, characterized in that The first dye system consists of a trichromatic pigment and a synthetic black pigment, wherein the content of the trichromatic pigment is 0.2% to 3%, preferably 0.4% to 1.5%, and more preferably 0.4% to 1%, and the content of the synthetic black pigment is 0.01% to 1%, preferably 0.02% to 0.5%, and more preferably 0.02% to 0.2%, based on the total weight of the photoluminescent material.

7. The photoluminescent material according to any one of the preceding claims, characterized in that The respective proportions of the green pigment, the blue pigment and the red pigment are 20% to 40% by weight of the total weight of the three-color pigment.

8. Photoluminescent material according to the preceding claim, characterized in that The green pigment, the blue pigment and the red pigment are present in the trichromatic pigment in the same proportion.

9. The photoluminescent material according to any one of claims 1 to 4, characterized in that The first dye system consists of 0.2% to 2%, preferably 0.3% to 1.5% and more preferably 0.3% to 1% of synthetic black pigment.

10. The photoluminescent material according to any one of the preceding claims, characterized in that The second dye system comprises 0.01% to 1%, preferably 0.01% to 0.5% and more preferably 0.01% to 0.3% carbon black, based on the total weight of the photoluminescent material.

11. The photoluminescent material according to any one of the preceding claims, characterized in that The porous silica is present in a percentage of 0.01% to 1%, preferably 0.07% to 0.3% and more preferably 0.09% to 0.2%.

12. The photoluminescent material according to any one of the preceding claims, characterized in that The porous silica is derived from a diatom skeleton.

13. A photoluminescent material according to any one of the preceding claims, characterised in that The photoluminescent compound comprises a pigment which is an alkaline earth metal aluminate derivative doped with a rare earth element.

14. Photoluminescent material according to the preceding claim, characterized in that The pigment has the formula Sr(x)Al(y)O(z):Eu 2+ ,Dy 3+ Alkaline earth metal aluminate derivatives doped with europium and dysprosium.

15. Photoluminescent material according to the preceding claim, characterized in that The pigment is Sr4Al 14 O 25 :Eu 2+ ,Dy 3+ and / or SrAl2O4:Eu 2+ ,Dy 3 .

16. The photoluminescent material according to any one of claims 13 to 15, characterized in that The photoluminescent compound consists of the pigment encapsulated in an organic transparent shell or an inorganic transparent shell.

17. A photoluminescent material according to any one of the preceding claims, characterised in that The polymer matrix comprises one or more resins from the acrylic family, the polyamide family, the polyolefin family, the epoxy family, the polyurethane family, the fluoroelastomer family and silicones.

18. The photoluminescent material according to claim 16, characterized in that The organic transparent shell comprises one or more resins from the acrylic family, the polyamide family, the polyolefin family, the epoxy family, the polyurethane family, the fluoroelastomer family and silicone, and the inorganic transparent shell comprises silicon dioxide.

19. The photoluminescent material according to any one of claims 13 to 18, characterized in that The photoluminescent compound includes pigments having different particle sizes.

20. Photoluminescent material according to the preceding claim, characterised in that The pigment has at least a first particle size range of 500 nm to 10 μm in diameter D1 and a second particle size range of 10 μm to 500 μm in diameter D2.

21. An article prepared from or coated with a photoluminescent material according to any one of the preceding claims.

22. Article according to the preceding claim, characterised in that This item is a watch part.