Dark-colored photoluminescent materials

Abstract

To provide a photoluminescent material having beautiful dark colors under light, while having good luminescent properties.SOLUTION: A photoluminescent material comprises 19.8-54.8% of a polymer matrix, 45-80 wt.% of a photoluminescent compound, 0.2-5 wt.% of a first dye system, and optionally 0-1 wt.% of porous silica, and a second dye system or additives, where the total content of the second dye system and additives is 0-15 wt.%. The first dye system comprises one or more kinds of dyes selected from synthetic black pigments and three-color pigments formed by green, blue and red pigments. The invention further relates to an article coated with the photoluminescent material or made as a whole of the photoluminescent material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a dark-colored photoluminescent material with optimized luminescence performance. [Background technology]

[0002] In the prior art, phosphorescent materials have been disclosed that are made from a mixture of a translucent or semi-translucent material and a photoluminescent pigment made from a mineral oxide doped with rare earth elements. For example, a mixture of 50% borosilicate and 50% europium and dysprosium-doped strontium aluminate (Eu 2+ Dy 3+ There are mixtures of 50% acrylic resin and 50% europium and dysprosium-doped strontium aluminate (SrAl2O4). The luminescence decay of these materials is initially exponential. For materials that have been saturated with light energy and then placed in the dark, the decay rate is several tens of Cd / m². 2 Starting from a brightness of 1, the brightness after 10 minutes in darkness is 1 Cd / m². 2 It becomes less than that. And the luminescence attenuation is several mCd / m 2 The value slowly approaches an asymptotic value. This allows these materials to maintain visible luminescence for up to 12 hours in the dark. These luminescent materials are necessary for good passive readability in diving equipment, and therefore, advancements in luminescence performance are eagerly awaited.

[0003] For aesthetic reasons, these photoluminescent materials can be stained using dye systems, which are mixtures of pigments and additives.

[0004] It is recognized that compounds used in photoluminescent materials containing pigments have properties that suppress luminescence. The luminescence of phosphorescent materials occurs as a result of physicochemical interactions between the various compounds in the photoluminescent material.

[0005] Therefore, optimizing both coloring and luminescence performance simultaneously is difficult. Tests were conducted using various carbon blacks for black, and generally for dark colors. It was observed that these carbon blacks excessively absorbed light within the absorption and emission range of the phosphorescent pigments, affecting the material's luminescence performance. Therefore, finding the optimal balance between color and photoluminescence is always necessary. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention relates to a novel composition that has good luminescence properties while enabling the acquisition of a beautiful black color under light, and generally a beautiful dark color under light. [Means for solving the problem]

[0007] In this context, the present invention proposes adding a mixture of pigments consisting of the three primary colors red, green, and blue, or a synthetic black pigment of the type C.1 Solvent Black 27, Brilliant Black BN, or Perylene Black, or a combination of the three primary colors and the synthetic black pigment to the formulation. This composition may contain the three primary colors to obtain a dark color, in which case the color is adjusted by adding the synthetic black pigment. Alternatively, the color can be adjusted by adding a small amount of carbon black. In another embodiment, to obtain a black with good phosphorescence, the composition contains only the synthetic black pigment, and optionally also contains a small amount of carbon black.

[0008] Optionally, the photoluminescent material may further contain porous silica obtained from algae to enhance its luminescence properties. This porous silica is obtained from the skeletons of diatoms. These diatom skeletons are microalgae, single-celled organisms with silica skeletons. In fact, recent biological research has shown that diatoms, single-celled algae that make up plankton, are composed of silica nanocells that can absorb sunlight with very high efficiency and perform photosynthesis efficiently even in the dark depths of the ocean. By adding a limited proportion of porous silica (less than 1% by weight) to the photoluminescent material, its luminescence properties can be improved.

[0009] Specifically, the present invention relates to a photoluminescent material comprising 19.8 to 54.8% by weight of a polymer matrix, 45 to 80% by weight of a photoluminescent compound, and 0.2 to 5% by weight of a first dye system, optionally comprising 0 to 1% by weight of porous silica, a second dye system, or an additive, wherein the total proportion of the second dye system and the additive is 0 to 15% by weight, and the first dye system comprises one or more dyes selected from a tricolor pigment formed by a green pigment, a blue pigment, and a red pigment, and a synthetic black pigment.

[0010] The present invention further relates to an article made entirely of the photoluminescent material, or coated with the photoluminescent material. [Modes for carrying out the invention]

[0011] The present invention relates to a dark-colored photoluminescent material that can be used to manufacture an article as a whole, and to coat an article. The article may be, for example, a component of a timepiece. In particular, the article may be an outer component selected from the group consisting of a middle section, a case back, a bezel, a crown, push buttons, bracelet links, a bracelet, a tang buckle, a clasp, a dial, a flange, a date disc, hands, and dial indices. However, this is not an exhaustive list.

[0012] The photoluminescence material includes a polymer matrix, a photoluminescence compound, and a first dye system, and optionally includes (consists of) porous silica, an additive, and a second dye system.

[0013] The first dye system that constitutes a more specific subject of the present invention includes one or more dyes selected from primary color pigments of the three primary colors formed by red, green, and blue, and a synthetic black pigment, preferably Solvent Black 27, perylene black, and / or Brilliant Black BN. The first dye system is contained at 0.2 to 5% by weight, preferably 0.3 to 4% by weight, more preferably 0.4 to 2% by weight.

[0014] For example, the main red pigment can be of the carmine (lacquer pigment derived from cochineal), azo, quinacridone, or perylene type. The main green pigment may be of the phthalocyanine or naphthol type, and the main blue pigment may be of the anthraquinone, phthalocyanine, or perylene type. Solvent Black 27 has the formula C 17 H 13 N3O4Cr 1 / 2 For example, it is sold under the brand name, Polysynthren® Black H. Brilliant Black BN, also called Black PN, is an azo dye and has the formula C 28 H 17 N5Na4O 14 S4. For example, it can be obtained from Sensient Cosmetic Technologies under the brand name, NOIR BRILLLANT BN 80% E151. Those skilled in the art can also use perylene black.

[0015] According to the first alternative embodiment, the first dye system comprises only three pigments. In this alternative embodiment, the proportion of the three pigments to the total weight of the photoluminescent material is 0.5 to 4% by weight, preferably 0.7 to 2% by weight. Preferably, the three pigments are present in equal proportions. For example, when adding up to 1.5% by weight of the three pigments, each pigment is added to 0.5% by weight of the total weight. This equal proportion can also be ignored by making the proportion of each pigment 20 to 40%. In the second alternative embodiment, the first dye system comprises 0.2 to 3% by weight, preferably 0.4 to 1.5% by weight, more preferably 0.4 to 1% by weight of the three pigments relative to the total weight of the photoluminescent material, and 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight, more preferably 0.02 to 0.2% by weight of a synthetic black pigment relative to the total weight of the photoluminescent material. In a third alternative embodiment, the first dye system comprises only 0.2 to 2% by weight, preferably 0.3 to 1.5% by weight, and more preferably 0.3 to 1% by weight, of the total weight of the photoluminescent material, a synthetic black pigment.

[0016] The polymer matrix is ​​present in an amount of 19.8 to 54.8% by weight, preferably 29.7 to 49.7% by weight, and more preferably 34.6 to 44.6% by weight. The upper limit of the polymer matrix is ​​calculated for a photoluminescent material that does not contain porous silica, a second dye system, or additives. In the presence of any one of these compounds, this upper limit is reduced so that none of the compounds in the photoluminescent material exceed 100%. In the case of a polymer matrix, the polymer matrix may contain all polymers that are translucent or semi-translucent in the visible region. For example, the polymer matrix may be a polymer that is one or more types of resins selected from the acrylic family, polyamide family, polyolefin family, epoxy family, polyurethane family, fluoroelastomer family, and silicone.

[0017] The photoluminescent compound is present in an amount of 45-80% by weight, preferably 50-70% by weight, and more preferably 55-65% by weight. The photoluminescent compound may consist of a pigment or a pigment encapsulated in a translucent shell. The pigment is preferably a rare earth-doped alkaline earth aluminate derivative. In particular, the pigment is of formula Sr x Al y O z :EU 2+ Dy 3+ The pigment is europium and dysprosium-doped strontium aluminate. In particular, the pigment is Sr4Al 14 O 25 :EU 2+ Dy 3+ , or SrAl2O4:Eu 2+ Dy 3+ This is possible, and optionally, both can be present in the photoluminescent compound. Advantageously, the pigment can have different particle sizes to optimally distribute the pigment in volume and avoid free space. Furthermore, the presence of different particle sizes in volume allows for a combination of small particles that form shallow surface traps, resulting in high light intensity over short periods, and larger particles that form deeper traps, resulting in longer-term light persistence. For example, the pigment can have a first particle size range centered on a diameter D1 of 500 nm to 10 μm, ideally 500 nm to 5 μm, and a second particle size range centered on a diameter D2 of 10 μm to 500 μm, ideally 10 μm to 20 μm, where the particle size is measured by laser particle size analysis ISO 13320:2020, which is optionally supplemented by SEM analysis using secondary electron imaging. Note that small portions of more than two particle sizes can be sieved and then combined. For example, it is possible to have a first sub-portion of 500 nm to 5 μm at 20% by weight, a second sub-portion of 5 μm to 20 μm at 60% by weight, and a third sub-portion of 20 μm to 50 μm at 20% by weight.

[0018] Optionally, the pigment can be encapsulated within a light-transmissive organic or mineral shell. The organic shell can typically be selected from the polymers mentioned for the polymer matrix. The mineral shell can be, for example, a silica (SiO2) shell obtained by the sol-gel method. Other examples of mineral shells include zirconium oxide (ZrO2) and aluminum oxide (Al2O3).

[0019] The photoluminescence material can optionally further contain, in total, 0 to 15% by weight, preferably 0 to 5% by weight, of a second dye system and additives. Advantageously, the photoluminescence material contains 0.5 to 5% by weight of a dye system and additives. The second dye system preferably includes an organic dye that does not absorb in the emission wavelength range of the photoluminescence pigment. This organic dye can be a fluorescent pigment or dye whose absorption is more in the UV range and emission is in the visible spectrum. For example, organic fluorescent pigments or dyes such as those with the trade names Radiant and Aralon®. It can also be a semi-transparent pigment or dye with a low absorption rate at the emission wavelength of the energy storage pigment. For example, it can be a semi-transparent pigment or dye by Clariant. The second dye system can also include carbon black to adjust the dark color. The proportion of carbon black is 0 to 1% by weight, preferably at most 0.5% by weight, more preferably at most 0.3% by weight. The lower limit when carbon black is present is 0.01% by weight. Therefore, the proportion of carbon black is 0.01 to 1% by weight, preferably 0.01 to 0.5% by weight, more preferably 0.01 to 0.3% by weight.

[0020] Metallic pigments and pigments with a pearlescent effect, UV-resistant additives for protecting the polymer matrix, dispersants such as silanes for promoting the dispersion of additives, and other additives such as silica-type nanoscale fillers for adapting the viscosity parameters of the mixture can also be added.

[0021] Optionally, the photoluminescent material may include porous silica obtained from diatom skeletons. Typically, the average pore diameter can be on the order of 500 nm. Optionally, the porous silica may be synthetic porous silica. In the case of synthetic silica, the average pore diameter is typically 0.1 μm to 3 μm. The porous silica is included in an amount of 0 to 1% by weight, preferably 0.01 to 1% by weight, more preferably 0.07 to 0.3% by weight, and even more preferably 0.09 to 0.2% by weight.

[0022] A method for producing articles made from photoluminescent materials generally involves mixing one or more polymers, preferably with a dispersant, intended to form a polymer matrix. This initial mixing is performed with photoluminescent pigments, which may optionally be pre-encapsulated. The first dye system is then added to this second mixture along with an optional second dye system, additives, and porous silica. This mixture can be produced from a liquid resin using a speed mixer or paddle mixer. The resulting mixture can then be molded by extrusion. Alternatively, the mixture can be produced using a twin-screw extruder or high-speed mixer to create a thermoplastic mixture and convert it into granules that can be reused for injection molding.

[0023] Methods for manufacturing articles coated with photoluminescent materials involve depositing the coating onto a substrate using techniques such as screen printing, pad printing, and spray coating.

[0024] Overall, the test to prepare samples using the aforementioned photoluminescent material involved a dye system containing the three primary colors and Solvent Black 27, and SrAl2O3:Eu 2+ Dy 3+The photoluminescent pigment was added to an epoxy resin containing 60% by weight of filler. The three primary colors were present at 0.6% by weight, with the same distribution for each color, and the proportion of Solvent Black 27 was 0.05% by weight. The same base material was also used, and a test was conducted using Solvent Black 27 at a proportion of 0.4% by weight relative to the total weight as the dye system. Furthermore, the same base material was used, and a test was conducted using the three primary colors at a proportion of 1.5% by weight relative to the total weight, with each color at a proportion of 0.5% by weight, as the dye system.

[0025] Furthermore, tests were conducted using an additional 0.2 wt% porous silica.

[0026] The samples were observed under a D65 light booth. In parallel, comparative tests were conducted using various black pigments, including carbon black with different particle sizes and structures, or minerals such as iron(III) oxide (Fe3O4) using the same base material.

[0027] This material was molded by vacuum casting.

[0028] When mineral oxides are used, the luminescent material fades very quickly. When carbon black is used, the color becomes very dark, but when used alone, the reduction in brightness is too great. Tests using the three primary colors alone, Solvent Black 27 alone, and combinations of these two resulted in satisfactory color under light and a 15% improvement in luminescence performance. In tests using porous silica, the luminescence properties increased by 20% after 10 minutes. These luminescence properties were measured according to ISO 17514-2003.

Claims

1. A photoluminescent material comprising 19.8 to 54.8% by weight of a polymer matrix, 45 to 80% by weight of a photoluminescent compound, and 0.2 to 5% by weight of a first dye system, and optionally comprising 0 to 1% by weight of porous silica, a second dye system, and additives, The total proportion of the second pigment system and the additive is 0 to 15% by weight, and the first pigment system includes one or more pigments selected from a tricolor pigment formed by a green pigment, a blue pigment and a red pigment, and a synthetic black pigment. The aforementioned synthetic black pigment is one of Solvent Black 27, Brilliant Black BN, Perylene Black, or a combination of at least two of these three. The photoluminescent compound is Sr4Al14O25:Eu2+,Dy3+, and / or contains a pigment of SrAl2O4:Eu2+,Dy3+. The polymer matrix comprises one or more resins selected from the acrylic family, polyamide family, polyolefin family, epoxy family, polyurethane family, fluoroelastomer family, and silicone. A photoluminescent material characterized by the following features.

2. The polymer matrix is ​​contained in 29.7 to 49.7% by weight, the photoluminescent compound in 50 to 70% by weight, and the first dye system in 0.3 to 4% by weight. The photoluminescent material according to feature 1.

3. The polymer matrix is ​​contained in 34.6 to 44.6% by weight, the photoluminescent compound in 55 to 65% by weight, and the first dye system in 0.4 to 2% by weight. The photoluminescent material according to feature 1.

4. The first pigment system contains 0.5 to 4% by weight of three pigments. The photoluminescent material according to feature 1.

5. The first dye system comprises three pigments in an amount of 0.2 to 3% by weight relative to the total weight of the photoluminescent material, and a synthetic black pigment in an amount of 0.01 to 1% by weight relative to the total weight of the photoluminescent material. The photoluminescent material according to feature 1.

6. The proportions of green, blue, and red pigments are each 20-40% by weight of the total weight of the three pigments. The photoluminescent material according to feature 1.

7. The green, blue, and red pigments are present in equal proportions in the three pigments. The photoluminescent material according to feature 6.

8. The first dye system consists of a synthetic black pigment in a proportion of 0.2 to 2% by weight. The photoluminescent material according to feature 1.

9. The second dye system contains carbon black in a proportion of 0.01 to 1% by weight relative to the total weight of the photoluminescent material. The photoluminescent material according to feature 1.

10. The porous silica is contained in a proportion of 0.01 to 1% by weight. The photoluminescent material according to feature 1.

11. The porous silica mentioned above was obtained from the skeleton of a diatom. The photoluminescent material according to feature 1.

12. The photoluminescent compound consists of the pigment encapsulated within an organic or mineral translucent shell. The photoluminescent material according to feature 1.

13. The organic translucent shell comprises one or more resins selected from the acrylic family, polyamide family, polyolefin family, epoxy family, polyurethane family, fluoroelastomer family, and silicone. The aforementioned translucent mineral shell contains silica. The photoluminescent material according to feature 12.

14. The photoluminescent compound includes pigments having various particle sizes. The photoluminescent material according to feature 1.

15. The pigment has at least a first particle size range centered on a diameter D1 of 500 nm to 10 μm, and a second particle size range centered on a diameter D2 of 10 μm to 500 μm. The photoluminescent material according to feature 14.

16. Made of or coated with the photoluminescent material described in claim 1 An article characterized by the following:

17. A component of a timekeeping device The article according to feature 16.