Energy storage self-luminous material for outdoor identification and preparation method thereof

Abstract

This invention discloses an outdoor signage energy-storage self-luminous material and its preparation method in the field of energy-storage self-luminous material technology. The energy-storage self-luminous material is a three-layer board, including a top layer, a middle layer, and a bottom layer. The raw materials, by mass percentage, include: 5%-45% dual-mechanism heat-sensitive luminescent powder; 50%-90% thermoplastic matrix; 0.1%-0.5% intelligent photothermal response additive; 4.0%-4.5% reinforcing filler; and 1.2%-2.5% weather-resistant protective component. The dual-mechanism heat-sensitive luminescent powder is composed of SrAl2O4:Eu... 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ After mixing with SiO2 upconversion powder, the mixture undergoes sequential chelation with 3-hydroxy-2-naphthoic acid-boronate, inorganic silicon-oxygen copolymerization, and fluorosilane crosslinking, followed by drying and curing. This invention, through the synergistic effect of multiple structures and components, comprehensively optimizes the luminescent properties, weather resistance, mechanical stability, and intelligent adaptability of outdoor signage materials, providing reliable technical support for the upgrading of outdoor signs such as road safety signs, highway signs, and tunnel emergency signs.

Description

Technical Field

[0001] This invention relates to the field of energy storage self-luminous materials, and more particularly to an energy storage self-luminous material for outdoor signage and its preparation method. Background Technology

[0002] Long-afterglow luminescent materials, with their unique advantages such as energy storage through absorption of natural / ambient light, autonomous and continuous luminescence in dark environments, passive and radiation-free operation, and green energy saving, have become ideal functional materials to replace traditional electroluminescent signs. Among them, alkaline earth aluminate systems (such as SrAl2O4:Eu) 2+ Dy 3+ It possesses characteristics such as high luminous brightness, long afterglow life, and relatively stable chemical properties, and has been initially applied in fields such as road markings and emergency signs (China Journal of Highway and Transport, 2026, 39(02):12-26.DOI:10.19721 / j.cnki.1001-7372.2026.02.002.). However, the intrinsic structure of aluminate long afterglow materials has significant shortcomings. Its crystal lattice contains a large number of easily hydrolyzed Al−O bonds and active alkaline earth metal sites, which are prone to hydrolysis under outdoor high temperature and humidity, rainwater leaching, and acid and alkali corrosion environments, generating hydroxide coating layers and destroying the crystal luminescent centers, leading to rapid loss of light and failure of the material. At the same time, single long afterglow materials rely on daytime ultraviolet-visible light energy storage, which is insufficient in cloudy days, tree shade, and semi-enclosed tunnel environments. The luminous intensity at night decays exponentially over time, and the brightness in the second half of the night is difficult to meet the road visibility distance requirements, making it impossible to achieve stable all-weather indication.

[0003] Existing technologies commonly employ methods such as silane coupling agent coating, in-situ polymerization coating of acrylate, and inorganic coating of silica / titanium dioxide to modify the surface of long afterglow particles (Xing Wennan. Preparation of Strontium aluminate luminescent coating based on silicone-acrylic emulsion [D]. Shenyang University of Technology, 2015.). While these methods can improve water resistance and interfacial compatibility to some extent, organic coatings have poor heat resistance and UV resistance, making them prone to thermal-oxidative aging, embrittlement, and cracking during long-term outdoor use, thus losing their protective function. Secondly, inorganic coatings are prone to pores and cracks, lacking density, allowing water molecules to still penetrate and erode the core. Conventional coatings only achieve physical protection and do not possess functions such as photosensitivity enhancement, energy transfer, or spectral modulation, thus failing to improve the material's efficiency in capturing and utilizing weak light.

[0004] In recent years, upconversion luminescent materials have been able to convert low-energy near-infrared light / weak ambient light into high-energy visible light, providing a new approach to solving the problems of insufficient energy storage and poor response in weak light with single long-afterglow materials. However, most existing upconversion long-afterglow composite systems are concentrated in biomedical fields such as bioimaging, fluorescent probes, and medical diagnosis, such as CN105802627A and CN110846037A. Their targets are near-infrared laser excitation, deep tissue penetration, and low biotoxicity. However, biomedical composite luminescent materials generally use fluoride matrices, nano-core-shell structures, and water-soluble surface modifications, which do not have road-grade weather resistance. Moreover, the preparation process is complex and costly, making them unsuitable for direct application in large outdoor signage products. Summary of the Invention

[0005] The purpose of this invention is to provide an energy-storing self-luminous material for outdoor signage and its preparation method, thereby solving the problems existing in the background art.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] This invention provides an energy-storing self-luminous material for outdoor signage. The energy-storing self-luminous material is a three-layer sheet, comprising a top layer, a middle layer, and a bottom layer. The raw materials for preparing each layer of the energy-storing self-luminous material, by weight percentage, include:

[0008] Dual-mechanism heat-sensitive luminescent powder 5%-45%;

[0009] Thermoplastic matrix 50%-90%;

[0010] Intelligent photothermal response additive: 0.1%-0.5%;

[0011] Reinforcing filler 4.0%-4.5%;

[0012] Weather-resistant protective components: 1.2%-2.5%;

[0013] The dual-mechanism heat-resistant sensitized luminescent powder is composed of SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3 + Er 3+ After mixing SiO2 upconversion powder, it is successively subjected to chelation of 3-hydroxy-2-naphthoic acid-boronic acid ester, inorganic silicon-oxygen copolymerization and fluorosilane crosslinking, and then dried and cured to obtain the final product.

[0014] As a further improvement to the present invention, the surface layer contains 35%-45% dual-mechanism heat-sensitive luminescent powder and 50%-60% thermoplastic matrix; the middle layer contains 15%-25% dual-mechanism heat-sensitive luminescent powder and 70%-80% thermoplastic matrix; and the bottom layer contains 5%-10% dual-mechanism heat-sensitive luminescent powder and 80%-90% thermoplastic matrix.

[0015] As a further improvement to the present invention, the thermoplastic matrix is ​​at least one of PP, PVC, PE, PP / PE blend, or POE toughening system.

[0016] As a further improvement to the present invention, the intelligent photothermal response additive includes an alkylated PNIPAM derivative and an azobenzene derivative, wherein the mass ratio of the alkylated PNIPAM derivative to the azobenzene derivative is (0.6-1.5):(0.4-1.0).

[0017] As a further improvement to the present invention, the reinforcing filler includes nano-silica and hollow glass microspheres.

[0018] As a further improvement to the present invention, the weather-resistant protective component includes fluorocarbon resin, nano-silicon nitride, and ultraviolet absorber, wherein the mass ratio of fluorocarbon resin, nano-silicon nitride, and ultraviolet absorber is (0.5-1.0):(0.3-0.8):(0.2-0.5).

[0019] As a further improvement to the present invention, the raw materials for preparing the energy storage self-luminous material further include: 0.3%-1.0% energy storage conductive agent.

[0020] As a further improvement to the present invention, the energy storage conductive agent is one of carbon nanotubes and conductive potassium titanate whiskers.

[0021] As a further improvement to the present invention, the preparation of the dual-mechanism heat-resistant sensitizing luminescent powder includes the following steps:

[0022] (1) SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 is added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; wherein the mass ratio of long afterglow powder to upconversion powder is (4-6):(2-4);

[0023] (2) Heat the mixed powder suspension to 50-60℃; add 3-hydroxy-2-naphthoic acid, the amount of which is 0.1wt%-1.0wt% of the mass of the mixed powder, adjust the pH to 8.0-9.0, add 0.1wt%-0.3wt% of tributyl borate, and keep warm;

[0024] (3) Add ethylene glycol to the system, heat to 70-80℃, add 0.1-0.5mol / L sodium silicate solution dropwise, and add methyltrimethoxysilane dropwise at the same time. Keep warm, lower the system temperature to 50-60℃, add epoxy fluorosilane, the amount of which is 0.5wt%-1.5wt% of the mass of the mixed powder; keep warm.

[0025] (4) Wash the mixed system product with ethanol multiple times, vacuum dry, and pre-crosslink and cure at 180-200℃.

[0026] This invention provides a method for preparing the above-mentioned energy-storing self-luminous material for outdoor signage, comprising the following steps:

[0027] (1) Dry the thermoplastic matrix at 70-90℃ for 2-4 hours; ball mill the dual-mechanism heat-sensitive luminescent powder at ≤40℃ to 5-20μm.

[0028] (2) Prepare surface, middle and bottom layer premixes separately, and premix them for 10-20 min at 800-1500 r / min and 60-90℃.

[0029] (3) The surface, middle and bottom premixes are formed by three-layer co-extrusion molding process at a temperature of 190-235℃. The melt diffusion inside the die forms a gradient. The substrate is annealed at 70-95℃ for 0.5-1h and then naturally cooled to obtain an energy storage self-luminous substrate.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) Through the long afterglow component (SrAl2O4:Eu) 2+ ,Dy 3+ ) and upconversion component (NaYF4:Yb 3+ Er 3+ The composite of SiO2 (@SiO2) forms a dual mechanism of energy storage and light emission, as well as energy replenishment in low light conditions, effectively solving the problems of insufficient energy storage and poor nighttime indication continuity in traditional single-light emission systems. Through multiple treatments, the technical problems of easy shedding and hydrolysis of luminescent powder during high-temperature extrusion have been solved, effectively adapting to complex outdoor environments such as rainy weather and strong ultraviolet radiation, and reducing the cost of sign maintenance and replacement.

[0032] (2) By introducing an oil-soluble alkylated PNIPAM and azobenzene composite smart additive, the material can achieve adaptive dimming in response to ambient temperature. At room temperature (25℃), the material maintains high brightness to ensure clear recognition at long distances; at high temperature (60℃), the brightness automatically decreases by 28.6%-32.5%, effectively avoiding glare interference caused by high temperature on outdoor sign surfaces in summer, and solving the problem of visual fatigue caused by fixed brightness of traditional high-brightness materials.

[0033] (3) The gradient structure with high luminescent powder content in the surface layer, transition in the middle layer, and high matrix content in the bottom layer is adopted. The high luminescent powder content in the surface layer ensures the high brightness effect, while the high proportion of polypropylene matrix in the bottom layer strengthens the mechanical support. This avoids the contradiction of embrittlement caused by high luminescent powder content in traditional homogeneous materials. It can withstand mechanical stresses such as transportation, installation and outdoor wind and vibration, and ensure the long-term stability of the sign structure.

[0034] (4) Using conventional three-layer co-extrusion equipment, gradient structure preparation is achieved through low-shear premixing and in-mold thermal diffusion molding process. No special precision equipment is required, resulting in high production efficiency and controllable cost. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the gradient concentration of the energy storage self-luminous material for outdoor signage in this invention;

[0036] Figure 2 This is a flowchart of the preparation method of the energy storage self-luminous material for outdoor signage in this invention;

[0037] Figure 3 This is a schematic diagram of the light emission of the energy storage self-luminous material prepared in Example 1 of the present invention. Detailed Implementation

[0038] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0039] At least one embodiment of this invention discloses an energy-storing self-luminous material for outdoor signage. The energy-storing self-luminous material is a three-layer sheet, including a top layer, a middle layer, and a bottom layer. The raw materials for preparing each layer of the energy-storing self-luminous material, by mass percentage, include:

[0040] Dual-mechanism heat-sensitive luminescent powder 5%-45%;

[0041] Thermoplastic matrix 50%-90%;

[0042] Intelligent photothermal response additive: 0.1%-0.5%;

[0043] Reinforcing filler 4.0%-4.5%;

[0044] Weather-resistant protective components: 1.2%-2.5%;

[0045] Among them, the dual-mechanism heat-resistant sensitized luminescent powder is SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er3 + The SiO2 upconversion powder is mixed and then sequentially subjected to chelation with 3-hydroxy-2-naphthoic acid-boronic acid ester, inorganic silicon-oxygen copolymerization, and fluorosilane crosslinking, followed by drying and curing to obtain the dual-mechanism heat-sensitive luminescent powder. The preparation includes the following steps:

[0046] (1) SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 is added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; wherein the mass ratio of long afterglow powder to upconversion powder is (4-6):(2-4);

[0047] (2) Heat the mixed powder suspension to 50-60℃; add 3-hydroxy-2-naphthoic acid, the amount of which is 0.1wt%-1.0wt% of the mass of the mixed powder, adjust the pH to 8.0-9.0, add 0.1wt%-0.3wt% of tributyl borate, and keep warm;

[0048] (3) Add ethylene glycol to the system, heat to 70-80℃, add 0.1-0.5mol / L sodium silicate solution dropwise, and add methyltrimethoxysilane dropwise at the same time. Keep warm, lower the system temperature to 50-60℃, add epoxy fluorosilane, the amount of which is 0.5wt%-1.5wt% of the mass of the mixed powder; keep warm.

[0049] (4) Wash the mixed system product with ethanol multiple times, vacuum dry, and pre-crosslink and cure at 180-200℃.

[0050] The thermoplastic matrix is ​​at least one of PP, PVC, PE, PP / PE blend, or POE toughening system.

[0051] Among them, the intelligent photothermal response additives include alkylated PNIPAM derivatives (oil-soluble alkylated PNIPAM derivatives are poly(N-isopropylacrylamide-co-acrylic acid long-chain alkyl ester), with an alkyl carbon chain length of C12-C18) and azobenzene derivatives (dimethyl azobenzene-4,4'-dicarboxylate), with a mass ratio of alkylated PNIPAM derivatives to azobenzene derivatives of (0.6-1.5):(0.4-1.0).

[0052] The reinforcing filler includes nano-silica (particle size 15-30nm, specific surface area 200-350m²). 2 / g) and hollow glass microspheres (15-60μm, D50=30μm), with a mass ratio of (1-2):(3-4) of nano-silica and hollow glass microspheres.

[0053] The weather-resistant protective components include fluorocarbon resin (polytetrafluoroethylene, perfluoroalkoxy resin, polyvinylidene fluoride, fluorinated ethylene propylene), nano-silicon nitride, and ultraviolet absorber UV-327. The mass ratio of fluorocarbon resin, nano-silicon nitride, and ultraviolet absorber is (0.5-1.0):(0.3-0.8):(0.2-0.5).

[0054] The raw materials for preparing the energy storage self-luminous material also include: 0.3%-1.0% of an energy storage conductive agent. The energy storage conductive agent is one of carbon nanotubes or conductive potassium titanate whiskers.

[0055] Among them, such as Figure 1 As shown, the surface layer contains 35%-45% dual-mechanism heat-sensitive luminescent powder, 50%-60% thermoplastic matrix, 0.1%-0.5% intelligent photothermal response additive, 4.0%-4.5% reinforcing filler, and 1.2%-2.5% weather-resistant protective component. The middle layer contains 15%-25% dual-mechanism heat-sensitive luminescent powder, 70%-80% thermoplastic matrix, 0.1%-0.5% intelligent photothermal response additive, 4.0%-4.5% reinforcing filler, and 1.2%-2.5% weather-resistant protective component. The bottom layer contains 5%-10% dual-mechanism heat-sensitive luminescent powder, 80%-90% thermoplastic matrix, 0.1%-0.5% intelligent photothermal response additive, 4.0%-4.5% reinforcing filler, and 1.2%-2.5% weather-resistant protective component.

[0056] At least one embodiment of this invention discloses a method for preparing the above-mentioned energy-storing self-luminous material for outdoor signage, such as... Figure 2 As shown, it includes the following steps:

[0057] (1) Dry the thermoplastic matrix at 70-90℃ for 2-4 hours; ball mill the dual-mechanism heat-sensitive luminescent powder at ≤40℃ to 5-20μm.

[0058] (2) Prepare surface, middle and bottom layer premixes separately, and premix them for 10-20 min at 800-1500 r / min and 60-90℃.

[0059] (3) The surface, middle and bottom premixes are formed by three-layer co-extrusion molding process at a temperature of 190-235℃. The melt diffusion inside the die forms a gradient. The substrate is annealed at 70-95℃ for 0.5-1h and then naturally cooled to obtain an energy storage self-luminous substrate.

[0060] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products, and all instruments used are conventional instruments known to those skilled in the art.

[0061] In the method used in this invention, the mass ratio of alkylated PNIPAM derivative to azobenzene derivative in the intelligent photothermal responsive additive is 0.6:0.4.

[0062] The mass ratio of nano-silica to hollow glass microspheres in the reinforcing filler is 1:3.

[0063] The mass ratio of polytetrafluoroethylene, nano-silicon nitride, and UV absorber UV-327 in the weather-resistant protective component is 1:0.3:0.2.

[0064] I. Methods

[0065] Example 1

[0066] The energy storage self-luminous material in this embodiment is prepared as follows:

[0067] (1) Preparation of dual-mechanism heat-resistant luminescent powder

[0068] SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 is added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; wherein the mass ratio of long afterglow powder to upconversion powder is 5:2;

[0069] Heat the mixed powder suspension to 50℃; add 3-hydroxy-2-naphthoic acid at a rate of 0.3 wt% of the mixed powder mass, adjust the pH to 8.0, add 0.1 wt% tributyl borate, and keep warm;

[0070] Add ethylene glycol to the system, heat to 80℃, add 0.2mol / L sodium silicate solution dropwise, and simultaneously add 2.0wt% methyltrimethoxysilane. Keep the temperature constant, then lower the system temperature to 50℃, add epoxy fluorosilane at a rate of 0.5wt% of the mixed powder mass, and keep the temperature constant.

[0071] The mixture was washed multiple times with ethanol, vacuum dried for 3 hours, and then pre-crosslinked and cured at 180°C.

[0072] (2) Raw material pretreatment

[0073] Polypropylene (PP) was dried in an oven at 70°C for 2 hours; the dual-mechanism heat-sensitive luminescent powder was ball-milled to 5-20 μm in a ball mill at 25°C.

[0074] (3) Ingredient premixing

[0075] The energy storage self-luminous material is a three-layer board, including a top layer, a middle layer and a bottom layer. The raw materials for preparation are shown in the table below (by mass percentage).

[0076]

[0077] The above-mentioned surface, middle and bottom layer premixes were all premixed for 20 minutes at 800 r / min and 60℃.

[0078] (4) Three-layer extrusion molding

[0079] ① The surface, middle, and bottom premixes were added to the hoppers of three extruders respectively. The three single-screw extruders were heated in stages, with the vacuum setting range being (-0.06) - (-0.08) MPa and the temperature setting as follows:

[0080] Surface extruder: Zone 1: 190℃, Zone 2: 205℃, Zone 3: 220℃, Zone 4: 225℃, screw speed 80 r / min;

[0081] Intermediate extruder: Zone 1: 185℃, Zone 2: 200℃, Zone 3: 215℃, Zone 4: 220℃, screw speed 120 r / min;

[0082] Bottom extruder: Zone 1: 180℃, Zone 2: 195℃, Zone 3: 210℃, Zone 4: 215℃, screw speed 140 r / min.

[0083] ② The three layers of melt enter the die head of the three-layer co-extrusion sheet respectively. The die head temperature is 215℃-230℃. The die head adopts a multi-channel composite structure so that the surface, middle and bottom layers of melt can be smoothly combined in the die head.

[0084] ③ The merged gradient melt flows out from the die head and enters the three-roll calender. The total thickness of the sheet is controlled to be 2.0-5.0 mm by controlling the gap between the three rolls. The process parameters of the three-roll calender are set as follows:

[0085] Front roller temperature: 65℃, middle roller temperature: 85℃, rear roller temperature: 100℃, linear speed: 1.2m / min.

[0086] ④ After calendering, the sheet material enters the tracked traction machine, and the speed is synchronized with the three rollers to ensure that the sheet material is not stretched or deformed; then it is cooled to room temperature through the air-cooled conveyor to fully set the shape of the sheet material.

[0087] ⑤ The board is placed in a constant temperature annealing furnace and annealed at 75°C for 1 hour. It is then slowly cooled to room temperature in the furnace to obtain an energy storage self-luminous substrate. Graphics are then printed on the substrate.

[0088] The prepared group 1 substrate and group 2 substrate are as follows Figure 3 As shown, it can be seen that the brightness is more obvious in the dark in the group 2 substrate with a higher content of luminescent powder.

[0089] Example 2

[0090] The energy storage self-luminous material in this embodiment is prepared using the same process as in Example 1, wherein the raw materials used in its preparation are as follows:

[0091]

[0092] Comparative Example 1

[0093] The energy storage self-luminescent material in this comparative example was prepared using the same process as in Example 1, and the raw material formulation was the same as in Example 1, except that the dual-mechanism heat-resistant sensitizing luminescent powder was replaced with SrAl2O4:Eu. 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 upconversion powder mixed powder.

[0094] Comparative Example 2

[0095] The energy storage self-luminescent material in this comparative example was prepared using the same process as in Example 1, and the raw material formulation was the same as in Example 1, Group 2. The only difference was that the dual-mechanism heat-resistant sensitizing luminescent powder was replaced with luminescent powder one. The preparation process of luminescent powder one is as follows:

[0096] SrAl2O4:Eu 2+ ,Dy 3+ Long-afterglow powder was added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension. The mixed powder suspension was heated to 50°C. 3-hydroxy-2-naphthoic acid was added at a rate of 0.3 wt% of the mixed powder mass, and the pH was adjusted to 8.0. 0.1 wt% tributyl borate was added, and the mixture was kept at this temperature. Ethylene glycol was added to the system, and the temperature was raised to 80°C. 0.2 mol / L sodium silicate solution was added dropwise, along with 2.0 wt% methyltrimethoxysilane. The mixture was kept at this temperature, and the temperature was lowered to 50°C. Epoxy fluorosilane was added at a rate of 0.5 wt% of the mixed powder mass. The mixture was kept at this temperature. The product was washed multiple times with ethanol, vacuum dried for 3 hours, and pre-crosslinked and cured at 180°C.

[0097] Comparative Example 3

[0098] The energy storage self-luminescent material in this comparative example was prepared using the same process as in Example 1, and the raw material formulation was the same as in Example 1, except that the dual-mechanism heat-resistant sensitizing luminescent powder was replaced with luminescent powder two. The preparation process of luminescent powder two is as follows:

[0099] SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+@SiO2 was added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; the mass ratio of long afterglow powder to upconversion powder was 5:2; ethylene glycol was added to the system, the temperature was raised to 80℃, 0.2mol / L sodium silicate solution was added dropwise, and 2.0wt% methyltrimethoxysilane was added dropwise at the same time. The temperature was kept at this temperature, and the system temperature was lowered to 50℃. Epoxy fluorosilane was added at a rate of 0.5wt% of the mixed powder mass; the temperature was kept at this temperature; the mixed system product was washed multiple times with ethanol, vacuum dried for 3 hours, and pre-crosslinked and cured at 180℃.

[0100] Comparative Example 4

[0101] The energy storage self-luminescent material in this comparative example was prepared using the same process as in Example 1, and the raw material formulation was the same as in Example 1, except that the dual-mechanism heat-resistant sensitizing luminescent powder was replaced with luminescent powder three. The preparation process of luminescent powder three is as follows:

[0102] SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 was added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; the mass ratio of long afterglow powder to upconversion powder was 5:2; the mixed powder suspension was heated to 50℃; 3-hydroxy-2-naphthoic acid was added at 0.3wt% of the mass of the mixed powder, the pH was adjusted to 8.0, 0.1wt% tributyl borate was added, and the mixture was kept at the same temperature; the product of the mixed system was washed multiple times with ethanol, vacuum dried for 3 hours, and pre-crosslinked and cured at 180℃.

[0103] Comparative Example 5

[0104] The energy storage self-luminous material of this comparative example was prepared in the same way as in Example 1, except that the raw material formulation did not contain the intelligent photothermal response additive (polypropylene PP was used instead), and the rest was the same as in Example 1, Group 2.

[0105] II. Tests and Conclusions

[0106] (1) Luminous properties

[0107] After exciting the sample with a 365nm UV lamp (30W) in a dark room for 10 min, the initial luminance, 10-minute luminance, 60-minute luminance, and 12-hour afterglow luminance were measured using a PR-650 luminance meter. The results are shown in the table below:

[0108]

[0109] As can be seen from the table above:

[0110] Example 1, Group 2: Initial luminance 9.5 cd / m² 2 12-hour afterglow brightness is 0.55 cd / m²2 All of them are superior to Group 1, proving that the gradient design with high luminescent powder content on the surface can directly improve the luminous intensity and the afterglow decays more slowly. The high matrix content in the bottom layer ensures the uniform dispersion of luminescent powder, avoiding the efficiency loss caused by luminescent powder agglomeration in the homogeneous structure, and achieving the unity of high brightness and long afterglow.

[0111] Example 2: Initial brightness 9.7 cd / m² 2 12-hour afterglow 0.57 cd / m 2 The result was slightly higher than that of Example 1 Group 2, indicating that the addition of the energy storage conductive agent did not affect the luminescence performance. On the contrary, it slightly improved the luminescence efficiency by optimizing the interfacial charge transfer, without sacrificing the afterglow durability, thus verifying the rationality of the formulation optimization.

[0112] The decay rate of Comparative Example 1 was much faster than that of the Example, possibly because the uncoated luminescent powder had more surface defects, making it easier for excited-state energy to be lost through lattice vibrations. Furthermore, the poor compatibility between the powder and the PP matrix and uneven dispersion led to localized luminescence quenching. This demonstrates that the dual-mechanism heat-sensitive luminescent powder of this invention possesses a certain degree of luminescence stability. The initial brightness of Comparative Example 2 was 8.3 cd / m². 2 However, the brightness is 5.1 cd / m² after 10 minutes. 2 60-minute brightness 1.3 cd / m² 2 12-hour afterglow 0.32 cd / m 2 The afterglow decays extremely quickly, presumably due to the lack of energy replenishment from the upconversion component. The long-afterglow powder relies solely on its own energy storage to emit light, and there is no secondary excitation after the energy is exhausted. This proves that the synergy of the two mechanisms is the key to achieving long-lasting afterglow, and a single long-afterglow system cannot meet the long-lasting needs of outdoor signage.

[0113] Comparative Examples 3-4 were all lower than the Example, possibly because the absence of the chelating layer resulted in poor bonding between the luminescent powder and the coating layer, hindering energy transfer; the absence of the SiO2 copolymer layer and the fluorosilicone layer led to oxidation of the luminescent powder surface, resulting in a decrease in excitation efficiency.

[0114] The luminescence performance of Comparative Example 5 is close to that of Example 1 Group 2, indicating that the intelligent photothermal response additive only acts on temperature regulation and does not affect luminescence efficiency and afterglow persistence. This verifies the independence and compatibility of each functional component and avoids the problem of performance mutual exclusion caused by the superposition of multiple functions.

[0115] (2) Mechanical properties and weather resistance

[0116] Tensile strength: GB / T1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics";

[0117] Impact strength: GB / T1843-2008 "Determination of impact strength of plastic cantilever beams";

[0118] Bending strength: GB / T9341-2008 "Determination of bending properties of plastics".

[0119] Water resistance: The sample was immersed in distilled water (pH=7) at 25℃ for 30 days, and after drying, the luminous brightness was tested and the brightness retention rate was calculated (brightness after immersion / brightness before immersion × 100%).

[0120] UV aging resistance: The luminous intensity decay rate was tested after 1000 hours of irradiation using a UVB-313 fluorescent UV lamp with an irradiance of 0.68 W / m² and a temperature of 60℃. The results are shown in the table below.

[0121]

[0122] As can be seen from the table above:

[0123] ①Mechanical properties

[0124] The tensile strength, impact strength, and flexural strength of Examples 1 and 2 are all superior to those of all comparative examples, and the mechanical properties of Group 2 are only slightly lower than those of Group 1. This demonstrates that the gradient structure achieves a balance between high luminescence and high strength through surface functionalization and bottom layer structural reinforcement. The high PP content in the bottom layer provides sufficient mechanical support, and the middle transition layer avoids stress concentration between layers. In Example 2, the addition of conductive potassium titanate whiskers improved the impact strength and tensile strength, indicating that the conductive agent forms tiny reinforcing points in the matrix, optimizing the stress transmission path and further improving the mechanical properties without affecting the flexural strength. Furthermore, it also has antistatic properties, preventing dust accumulation on the substrate.

[0125] Comparative Example 1 showed significantly lower performance than the Example, possibly because the uncoated luminescent powder had poor interfacial compatibility with the PP matrix, resulting in numerous microscopic voids. Under stress, these voids easily caused stress concentration, leading to material brittleness. Comparative Examples 2-5 were similar to the Example, indicating that the absence of dual mechanisms, intelligent additives, and a single coating layer had minimal impact on mechanical properties, demonstrating that the design of other functional components did not sacrifice structural stability.

[0126] ② Water resistance test

[0127] The brightness retention rate of Examples 1-2 after 30 days of immersion in water was ≥95.2%, with Example 2 reaching 96.8%. This is presumably due to the formation of a triple-coating structure on the surface of the luminescent powder, resulting in a dense hydrophobic protective film. The inner chelating layer covalently bonds with metal ions on the luminescent powder surface, the middle SiO2 copolymer layer forms an inorganic rigid barrier, and the outer fluorosilane provides a hydrophobic surface. This triple barrier completely prevents water molecule penetration, avoiding hydrolytic failure of the luminescent powder (such as the hydrolysis of SrAl2O4 to form aluminum hydroxide, which destroys the crystal structure). Comparative Example 1 is presumably due to water molecules directly penetrating into the interior of the luminescent powder, causing lattice breakage and affecting the luminescent center Eu. 2+ Dy 3+Oxidation completely destroys the luminescent properties. Comparative Example 2 is speculated to be due to the higher hydrolysis sensitivity of long afterglow powder compared to dual-mechanism composite powder, and the lack of energy compensation through dual-mechanism synergy, resulting in more significant brightness decay after hydrolysis. Comparative Example 3 is speculated to be due to the lack of anchoring effect of the chelating layer, resulting in weak bonding between the coating layer and the luminescent powder, allowing water molecules to easily penetrate through the interface gaps. Comparative Example 4 is speculated to be due to the inability of the chelating layer alone to form complete protection, and the lack of hydrophobic function of the fluorosilicone layer, which leads to water molecules easily adsorbing onto the surface and penetrating.

[0128] ③ Resistance to UV aging

[0129] In Example 1, the brightness decay rate after 1000 hours of UV aging was ≤7.5%, while in Example 2 it was only 6.5%. It is speculated that this may be due to the formation of a triple coating structure on the surface of the luminescent powder. The triple coating layer works synergistically with the weather-resistant components. The outer fluorosilane layer has excellent UV shielding performance, the middle SiO2 copolymer layer blocks UV penetration, the UV-327 in the weather-resistant components absorbs UV light, and the nano-silicon nitride disperses UV light. This multiple protection prevents the luminescent powder from lattice defects and oxidation of the luminescent center caused by UV irradiation.

[0130] (3) Brightening response in low light

[0131] Irradiate the sample with a 980nm near-infrared laser (50mW power, simulating the weak light of a car headlight), test the luminous brightness before and after irradiation, and calculate the brightening factor (brightness after irradiation / brightness before irradiation × 100% - 100%).

[0132]

[0133] As shown in the table above, the outdoor signage of this invention possesses passive brightening capabilities in low-light environments such as cloudy days, tunnels, and nighttime. The low-light brightening factor of Examples 1-2 is ≥52.1%, with Example 2 reaching 65.8%, demonstrating a significant synergistic effect of the dual mechanisms. The upconversion powder NaYF4:Yb... 3+ Er 3+ It can efficiently absorb 980nm near-infrared weak light and convert it into visible light (520nm, 540nm, 660nm). It not only emits its own light but also excites the luminescent centers of the long-afterglow powder, achieving a brightening effect greater than the sum of its parts (1+1>2), thus solving the problem of insufficient energy storage in low-light environments. In Example 1, the brightening factor of Group 2 was higher than that of Group 1, indicating that the higher the content of surface luminescent powder, the greater the probability of contact between the upconversion component and the long-afterglow powder, resulting in higher energy transfer efficiency and a more significant brightening effect. This verifies the compatibility of the gradient structure design and the dual-mechanism approach.

[0134] Comparative Example 1, due to numerous surface defects in the uncoated upconversion powder, exhibited low near-infrared light absorption efficiency and uneven dispersion with the long-afterglow powder, hindering energy transfer. This demonstrates that the triple coating layer can protect the lattice integrity of the upconversion powder and improve light absorption and energy conversion efficiency. Comparative Example 2, because the long-afterglow powder cannot absorb near-infrared light and can only emit light through ultraviolet / visible light storage, lacks an excitation source in low-light environments. This proves that the upconversion component is key to achieving low-light brightening, and a single long-afterglow system lacks low-light response capability. Comparative Examples 3-4 showed lower results than the examples, with incomplete coating layers leading to decreased light absorption efficiency and hindered energy transfer. This demonstrates that the triple coating layer can optimize the optical performance of the upconversion powder and ensure the synergistic brightening effect of the dual mechanisms. Comparative Example 5, with a brightening factor of 62.8%, is close to that of Example 1 Group 2, indicating that the intelligent additive does not affect the low-light response performance of the dual mechanisms and only focuses on temperature control.

[0135] (4) Intelligent light-temperature response test

[0136] In a dark room, the luminance of the sample after excitation was tested at 25℃ (normal temperature) and 60℃ (high temperature), and the luminance change rate at high temperature was calculated as ((60℃ luminance - 25℃ luminance) / 25℃ luminance × 100%).

[0137]

[0138] Outdoor signage, if too bright in high-temperature summer environments (e.g., 60℃), can easily cause glare and interfere with vision; therefore, it needs to maintain high brightness at room temperature. As can be seen from the table above, the energy storage self-emissive substrate prepared by this invention has a temperature-adaptive dimming function.

[0139] The brightness change rate at 60℃ in Examples 1-2 was (-28.6%) to (-32.5%), demonstrating that the oil-soluble intelligent additive has good compatibility with the PP matrix and can achieve precise temperature control. At room temperature (25℃), the additive molecules are in a relaxed state, which does not affect light transmission and excitation of luminescent powder. At high temperature (60℃), the molecules shrink and form tiny light-blocking points, reducing light transmittance and inhibiting the energy release of luminescent powder, thus achieving the intelligent functions of high-temperature anti-glare and high brightness at room temperature, solving the problem of fixed brightness and easy glare in traditional signs.

[0140] The rate of change in Example 2 was slightly higher than that in Example 1, indicating that conductive potassium titanate whiskers do not affect the temperature response performance of the smart additive, and may make the additive molecules more sensitive to temperature by optimizing heat transfer.

[0141] Comparative Example 1 showed a 0% change rate. Due to the poor compatibility between the uncoated luminescent powder and the matrix, microscopic voids led to uneven heat transfer, preventing the intelligent additive from sensing uniform temperature. Furthermore, the powder's luminescence efficiency was low, showing no significant brightness difference even with temperature changes. This demonstrates that the triple coating layer ensures structural uniformity, providing a foundation for intelligent control. Comparative Example 2 showed no substantial control effect. The low luminescence intensity of the single long-afterglow system, coupled with the lack of dual-mechanism synergistic energy regulation, resulted in an insignificant light-blocking effect from the intelligent additive. This proves that high brightness from dual-mechanism luminescence is a prerequisite for intelligent control, and low-brightness systems cannot demonstrate temperature response. Comparative Examples 3-4 showed lower change rates than the examples. Incomplete coating layers resulted in insufficient structural density, uneven heat transfer, and inconsistent molecular shrinkage of the intelligent additive, weakening the control effect. This demonstrates that the structural uniformity of the triple coating layer is crucial for the accuracy of intelligent control. Comparative Example 5 showed almost no control effect, proving that intelligent photothermal response additives are key to achieving temperature-adaptive dimming.

[0142] The energy storage self-luminous material prepared by this invention can effectively solve the problems of poor recognition in weak light, easy glare at high temperature, insufficient weather resistance, and poor mechanical properties of traditional outdoor signage materials. Its luminous performance, weather resistance, mechanical properties, and intelligent control function are all precisely matched to the usage requirements of outdoor signs such as road safety signs, highway signs, and tunnel emergency signs. Moreover, the preparation process is mature and the cost is controllable, which has broad application prospects and promotion value.

[0143] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An energy-storing self-luminous material for outdoor signage, wherein the energy-storing self-luminous material is a three-layer sheet comprising a surface layer, a middle layer, and a bottom layer, characterized in that, By mass percentage, the raw materials for preparing each layer of the energy storage self-luminous material include: Dual-mechanism heat-sensitive luminescent powder 5%-45%; Thermoplastic matrix 50%-90%; Intelligent photothermal response additive: 0.1%-0.5%; Reinforcing filler 4.0%-4.5%; Weather-resistant protective components: 1.2%-2.5%; The dual-mechanism heat-resistant sensitized luminescent powder is composed of SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3 + After mixing SiO2 upconversion powder, it is successively subjected to chelation with 3-hydroxy-2-naphthoic acid-boronic acid ester, inorganic silicon-oxygen copolymerization and fluorosilane treatment, and then dried and cured to obtain the final product.

2. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The surface layer contains 35%-45% dual-mechanism heat-sensitive luminescent powder and 50%-60% thermoplastic matrix; the middle layer contains 15%-25% dual-mechanism heat-sensitive luminescent powder and 70%-80% thermoplastic matrix; and the bottom layer contains 5%-10% dual-mechanism heat-sensitive luminescent powder and 80%-90% thermoplastic matrix.

3. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The thermoplastic matrix is ​​at least one of PP, PVC, PE, PP / PE blend, or POE toughening system.

4. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The intelligent photothermal response additive includes alkylated PNIPAM derivatives and azobenzene derivatives, wherein the mass ratio of the alkylated PNIPAM derivatives to the azobenzene derivatives is (0.6-1.5):(0.4-1.0).

5. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The reinforcing filler includes nano-silica and hollow glass microspheres.

6. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The weather-resistant protective component includes fluorocarbon resin, nano-silicon nitride, and ultraviolet absorber, wherein the mass ratio of fluorocarbon resin, nano-silicon nitride, and ultraviolet absorber is (0.5-1.0):(0.3-0.8):(0.2-0.5).

7. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The raw materials for preparing the energy storage self-luminous material also include: 0.3%-1.0% energy storage conductive agent.

8. The energy-storing self-luminous material for outdoor signage according to claim 7, characterized in that, The energy storage conductive agent is one of carbon nanotubes or conductive potassium titanate whiskers.

9. The energy-storing self-luminous material for outdoor signage according to claim 1, characterized in that, The preparation of the dual-mechanism heat-resistant sensitizing luminescent powder includes the following steps: (1) SrAl2O4:Eu 2+ ,Dy 3+ Long afterglow powder and NaYF4:Yb 3+ Er 3+ @SiO2 is added to anhydrous ethanol and ultrasonically dispersed to form a uniform suspension; wherein the mass ratio of long afterglow powder to upconversion powder is (4-6):(2-4); (2) Heat the mixed powder suspension to 50-60℃; add 3-hydroxy-2-naphthoic acid, the amount of which is 0.1wt%-1.0wt% of the mass of the mixed powder, adjust the pH to 8.0-9.0, add 0.1wt%-0.3wt% of tributyl borate, and keep warm; (3) Add ethylene glycol to the system, heat to 70-80℃, add 0.1-0.5mol / L sodium silicate solution dropwise, and add methyltrimethoxysilane dropwise at the same time. Keep warm, lower the system temperature to 50-60℃, add epoxy fluorosilane, the amount of which is 0.5wt%-1.5wt% of the mass of the mixed powder; keep warm. (4) Wash the mixed system product with ethanol multiple times, vacuum dry, and pre-crosslink and cure at 180-200℃.

10. A method for preparing an energy-storing self-luminous material for outdoor signage as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Dry the thermoplastic matrix at 70-90℃ for 2-4 hours; ball mill the dual-mechanism heat-sensitive luminescent powder at ≤40℃ to 5-20μm. (2) Prepare surface, middle and bottom layer premixes separately, and premix them for 10-20 min at 800-1500 r / min and 60-90℃. (3) The surface, middle and bottom premixes are formed by three-layer co-extrusion molding process at a temperature of 190-235℃. The melt diffusion inside the die forms a gradient. The substrate is annealed at 70-95℃ for 0.5-1h and then naturally cooled to obtain an energy storage self-luminous substrate.

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