Efficient photoluminescent material

Abstract

To provide a photoluminescent material that limits the light emission associated with compounds added.SOLUTION: A photoluminescent material contains 19.99-54.99 wt.% of a polymer matrix, 45-80 wt.% of a photoluminescent compound, 0.01-1 wt.% of porous silica, and optionally a dye system and additives with a total content of 0-15 wt.%. Also provided is an article made of or coated with the photoluminescent material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a photoluminescence material with improved luminescence performance.

Background Art

[0002] Luminescent materials made from a mixture of a translucent or semi-translucent material and a photoluminescence pigment made from a mineral oxide doped with rare earth elements are already known. By way of example, there are mixtures of 50% borosilicate and 50% strontium aluminate doped with europium or dysprosium (Eu 2+ , Dy 3+ :SrAl2O4), and mixtures of 50% acrylic resin and 50% strontium aluminate doped with europium or dysprosium. The luminescence decay of these materials is exponential initially. When placed in the dark after being saturated with light energy, for a material starting with a luminance of several tens of Cd / m 2 , the luminance after 10 minutes in the dark is less than 1 Cd / m 2 . And the luminescence decay slowly approaches the asymptotic value at several mCd / m 2 . Thanks to this, these materials can sustain visible luminescence in the dark for up to 12 hours. For the passive readability of diving equipment to be good, these luminescent materials are passively required, and thus, progress in luminescence performance is awaited.

[0003] Since the luminescent pigment is susceptible to the influence of humidity, it is desirable to create a photoluminescence decoration to encapsulate the pigment within a translucent material and manufacture the photoluminescence material. For aesthetic reasons, especially for the perception of sunlight, these photoluminescence materials can also be dyed using a pigment system that is a mixture of pigments and additives.

[0004] It has been recognized that compounds used in photoluminescence materials containing pigments have properties that suppress luminescence properties. The luminescence of the energy storage material occurs as a result of physicochemical interactions between various compounds of the photoluminescence material.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention relates to developing a new composition of a photoluminescence material that limits the suppression of luminescence associated with the compounds added to this composition.

Means for Solving the Problems

[0006] In such a situation, it is proposed to add a porous silica type dopant obtained from algae to the composition. Porous silica is obtained from the skeletons of diatoms. These are microalgae, which are single-celled organisms having a silica skeleton. In fact, according to the latest biological research, diatoms, which are single-celled algae constituting plankton, are composed of silica nanocells that can absorb sunlight with very high efficiency and perform photosynthesis efficiently even in the dark deep sea.

[0007] According to the present invention, by adding a limited proportion of porous silica of 1% by weight or less to the photoluminescence material, the luminescence characteristics can be significantly improved.

[0008] Specifically, the present invention relates to a photoluminescence material containing 19.99 to 54.99% by weight of a polymer matrix, 45 to 80% by weight of a photoluminescence compound, and 0.01 to 1% by weight of porous silica, and optionally containing pigment systems and additives with a total content of 0 to 15% by weight.

Modes for Carrying Out the Invention

[0009] The present invention relates to a photoluminescence material containing porous silica. The present invention further relates to an article coated with or made of this photoluminescence material. This article can be, for example, a component of a timepiece. In particular, the article can be a component selected from the group consisting of a case middle part, a case back part, a bezel, lugs, push buttons, bracelet links, a bracelet, a tang buckle, a clasp, a watch face, a flange, a date disk, watch face hands, and watch face indexes. Note that these do not cover all of them.

[0010] The photoluminescence material contains a polymer matrix, a photoluminescence compound, and porous silica, and optionally contains (consists of) a pigment system and additives.

[0011] Based on the total weight of the photoluminescence material, the porous silica is contained in an amount of 0.01 to 1% by weight, preferably 0.07 to 0.3% by weight, more preferably 0.09 to 0.2% by weight. This is porous silica derived from the skeleton of diatoms. Typically, the average diameter of the pores can be on the order of 500 nm. The porous silica can further be synthetic porous silica. In the case of synthetic silica, the average diameter of the pores is typically 0.1 μm to 3 μm. The polymer matrix is contained in an amount of 19.99 to 54.99% by weight, preferably 29.93 to 49.93% by weight, more preferably 29.91 to 49.91% by weight. This can include all polymers that are translucent or semi-translucent in the visible range. By way of example, the polymer can be one or more of the polymers that are resins selected from the acrylic family, the polyamide family, the polyolefin family, the epoxy family, the polyurethane family, the fluoroelastomer family, and silicone. The photoluminescence compound is contained in an amount of 45 to 80% by weight, preferably 50 to 70% by weight. The photoluminescence compound can consist of a pigment or a pigment encapsulated in a shell. The pigment is preferably a derivative of an alkaline earth aluminate doped with rare earths. In particular, the pigment has the formula Srx Al y O z :Eu 2+ 、Dy 3+ is europium- or dysprosium-doped strontium aluminate. In particular, the pigment is Sr4Al 14 O 25 :Eu 2+ 、Dy 3+ 、or SrAl2O4:Eu 2+ 、Dy 3+ and optionally both can be included in the photoluminescence compound. Advantageously, the pigment can have different particle sizes so as to be optimally distributed in the volume of the pigment and avoid free space. Also, due to the presence of different particle sizes in the volume of the pigment in this way, it becomes possible to combine small particles that form shallow surface traps causing high light intensity over a short period of time with large particles that form deeper traps causing light residue over a long period of time. By way of 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, and the particle size is measured by laser particle size analysis ISO 13320:2020, which is supplemented in some cases by SEM analysis using secondary electron imaging. It should be noted that a combination can be made after sieving out small portions of more than two numbers of particle sizes. For example, it is possible to have a first small portion of 20% by weight of 500 nm to 5 μm, a second small portion of 60% by weight of 5 μm to 20 μm, and a third small portion of 20% by weight of 20 μm to 50 μm.

[0012] The pigment can be encapsulated within a light-transmissive organic or mineral shell. The organic shell can typically be selected from the polymers mentioned with respect to the polymer matrix. In the case of a mineral shell, for example, it can be a silica shell (SiO2) obtained by the sol-gel method. Other examples of mineral shells include zirconium oxide (ZrO2) and aluminum oxide (Al2O3). The photoluminescence material optionally contains 0 to 15% by weight, preferably 0 to 5% by weight, of dye systems and additives. The dye system preferably includes an organic dye that does not absorb light in the emission wavelength range of the photoluminescence pigment. This organic dye can be a pigment or fluorescent dye whose absorption is more in the UV range and whose emission is in the visible spectrum. For example, this pigment or fluorescent dye can be an organic fluorescent pigment or dye such as the brands Radiant and Aralon®. It can also be a semi-translucent pigment or dye with a low absorption rate at the emission wavelength of the energy storage pigment. For example, it can be a semi-translucent pigment or dye of the brand Clariant. Other additives can also be added, such as metallic pigments and pigments with pearlescent effects, UV-resistant additives to protect the polymer matrix, dispersants such as silanes to promote the dispersion of the additives, and silica-type nanoscale fillers to adapt the viscosity parameters of the mixture.

[0013] This method involves mixing a polymer intended to form a polymer matrix, preferably with a dispersant. This first mixture is made with a photoluminescence pigment that may have been pre-encapsulated. Then, porous silica is added to this second mixture, along with any optional dye systems and additives. This mixture can be made from a liquid resin using a speed mixer or a paddle mixer. The resulting mixture can then be shaped by extrusion. It can also be made using a twin-screw extruder or a high-speed mixer to produce a thermoplastic mixture and convert it into reusable pellets for injection molding.

[0014] Tests were conducted by adding 0.09 to 0.2 wt% of porous silica to a two-component epoxy resin containing an amide hardener, with respect to the total weight of the photoluminescence material. A photoluminescence pigment formed by europium- and dysprosium-doped strontium aluminate was added at a filler ratio of 50% with respect to the total weight of the photoluminescence material.

[0015] The material was formed by casting this mixture. A person skilled in the art could easily convert this composition into other types of polymeric materials that can be injection-molded or extruded. Also, for application by screen printing, pad printing, spraying, etc., this composition can be easily converted into a dispersant of the polymer in a solvent.

[0016] The luminescence properties were measured according to the ISO 17514-2003 standard, and an improvement of 5 to 7% was observed compared to the same composition without the addition of porous silica.

Claims

1. Comprising 19.99 to 54.99% by weight of a polymer matrix, 45 to 80% by weight of a photoluminescence compound, and 0.01 to 1% by weight of porous silica, Optionally containing pigment systems and additives with a total content of 0 to 15% by weight A photoluminescence material characterized by this.

2. Containing 29.93 to 49.93% by weight of the polymer matrix, Containing 50 to 70% by weight of the photoluminescence compound, Containing 0.07 to 0.3% by weight of the porous silica The photoluminescence material according to Claim 1, characterized by this.

3. Containing 29.91 to 49.91% by weight of the polymer matrix, Containing 50 to 70% by weight of the photoluminescence compound, Containing 0.09 to 0.2% by weight of the porous silica The photoluminescence material according to Claim 1, characterized by this.

4. The porous silica is obtained from the skeleton of diatoms The photoluminescence material according to Claim 1, characterized by this.

5. The photoluminescence compound contains a pigment that is a derivative of an alkaline earth aluminate doped with rare earths The photoluminescence material according to Claim 1, characterized by this.

6. The pigment is of the formula Sr x Al y O z :Eu 2+ ,Dy 3+ and is a derivative of an alkaline earth aluminate doped with europium and dysprosium The photoluminescence material according to Claim 5, characterized by this.

7. The pigment is Sr 4 Al 14 O 25 : Eu 2+ , Dy 3+ , and / or SrAl 2 O 4 : Eu 2+ , Dy 3+ is The photoluminescence material according to Claim 6, characterized by this.

8. The photoluminescence compound is composed of the pigment encapsulated within a translucent organic or mineral shell The photoluminescence material according to Claim 5, characterized by this.

9. The polymer matrix contains one or more resins selected from the acrylic family, polyamide family, polyolefin family, epoxy family, polyurethane family, fluoroelastomer family, and silicone The photoluminescence material according to Claim 1, characterized by this.

10. The translucent organic shell contains one or more resins selected from the acrylic family, polyamide family, polyolefin family, epoxy family, polyurethane family, fluoroelastomer family, and silicone, The translucent inorganic shell contains silica The photoluminescence material according to Claim 8, characterized by this.

11. The photoluminescence compound contains pigments with different particle sizes The photoluminescence material according to claim 5, characterized in that...

12. 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 photoluminescence material according to claim 11, characterized in that...

13. An article made of or coated with the photoluminescence material according to claim 1. Characterized by...

14. It is a component of a timepiece. The article according to claim 13, characterized in that...