A high performance light emitting fiber driven by a safe voltage and a preparation method thereof

Abstract

The present application belongs to the technical field of functional textile fibers, and particularly relates to a high-performance light-emitting fiber driven by a safe voltage and a preparation method thereof. The light-emitting fiber of the present application comprises, from inside to outside, a cylindrical conductive fiber electrode, a dielectric layer, a light-emitting layer, an outer fiber electrode, and a shell-imitating pearl encapsulation layer. The preparation process comprises: loading conductive paste onto the surface of a textile fiber by coating to obtain a conductive fiber with a conductive layer; loading a dielectric layer and a light-emitting layer; winding an outer fiber electrode on the surface of the light-emitting layer; simulating the structure of a shell pearl layer to form an encapsulation layer on the surface of the light-emitting fiber; and the encapsulation layer has excellent properties such as mechanical rubbing resistance and heat aging resistance. The present application improves the uniformity of the electric field at the high-curvature interface, so that more light-emitting particles are effectively excited by the electric field to emit light, thereby improving the light-emitting brightness. The brightness can reach 127 cd / m 2 under the driving of 36 V / 2 kHz alternating current, and the light-emitting fiber has the characteristics of being driven by a safe voltage for the human body, improving the wearable safety, and reducing the power consumption.

Description

Technical Field

[0001] This invention belongs to the field of functional textile fiber technology, specifically relating to a high-performance luminescent fiber driven by a safe voltage and its preparation method. Background Technology

[0002] Electroluminescent fibers, due to their excellent flexibility, can be woven into soft and breathable luminescent fabrics using various weaving methods, exhibiting unique advantages in wearable devices. DC electroluminescent fibers, such as OLED, PLED, and QLED fibers, produce light by directly injecting holes and electrons into the light-emitting layer, resulting in high luminous efficiency. However, AC electroluminescent devices emit light by repeatedly accelerating and colliding with the luminescent center under an alternating electric field. This involves issues such as the frequency of the AC electric field and AC coupling energy loss, resulting in higher driving voltage and lower brightness.

[0003] However, the fabrication conditions for DC electroluminescent fibers are quite demanding, requiring an anhydrous, oxygen-free, and clean environment, high requirements for film flatness, and strict water and oxygen isolation encapsulation to ensure a certain luminescence lifetime. AC electroluminescent fibers, on the other hand, have slightly lower requirements for film flatness, better water and oxygen resistance, and do not require stringent encapsulation, reducing the difficulty of flexible fiber encapsulation. Therefore, compared to DC electroluminescent fibers, AC electroluminescent fibers are easier to fabricate on a large scale continuously, and currently, mainstream and well-developed fiber optic devices still use AC electroluminescent materials. However, achieving a breakthrough in luminous brightness is a key requirement for these devices to achieve practical applications, especially ensuring normal display functionality under high illumination conditions. Currently, zinc sulfide luminescent powder based on the electroluminescence principle is the core active material for AC-electric electroluminescent fibers. Its advantage lies in its ability to be mass-produced through continuous processes, resulting in luminescent fibers with fine diameters, good flexibility, and ease of weaving, as described in patents CN202210444431.1, CN202210568318.4, and CN202111312835.7. However, current luminescent fibers face problems such as low luminous brightness, high driving voltage, and difficulty in outdoor or high-illuminance environments, representing a critical technological bottleneck that urgently needs to be overcome. Furthermore, current patent reports and commercially available electroluminescent fibers primarily focus on luminescence performance and color changes, neglecting the design of their surface protective coating materials. This results in defects such as poor resistance to mechanical friction, solvents, and weathering, making them unsuitable for practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance luminescent fiber that can be driven at a safe voltage of up to 36V and a method for preparing the same.

[0005] The high-performance luminescent fiber provided by this invention has the following structural composition from the inside out: a quasi-cylindrical conductive fiber electrode, a dielectric layer, a luminescent layer, an outer fiber electrode, and a shell-like pearl encapsulation layer; see also Figure 1 As shown, the preparation process is as follows: First, the resin is dissolved in a solvent to obtain an organic carrier; then, conductive materials and conductive additives are added to the organic carrier, and after thorough ball milling, a high-performance conductive slurry is obtained; the conductive slurry is loaded onto the textile fiber bundles and fiber surface using a coating method to form a conductive layer, resulting in a highly conductive fiber bottom electrode with high flatness; subsequently, inorganic ceramic powder and electroluminescent active materials are added to a polymer solution, and after centrifugation, degassing, and stirring, dielectric slurry and luminescent slurry are obtained respectively; the dielectric slurry and electroluminescent active slurry are sequentially loaded onto the surface of conductive fibers using a coating method, and then the conductive fibers are wound as external electrodes to prepare luminescent fibers. Finally, mimicking the nacreous structure of seashells, alternating "soft-hard" interface layers are sequentially designed on the surface of the luminescent fibers, and thermal curing crosslinking is performed using a corresponding crosslinking agent to form a uniform, dense, and durable encapsulation protective coating. This coating has excellent resistance to mechanical friction, solvents, acids and alkalis, heat aging, light aging, and weaving. Meanwhile, the uniform and smooth conductive coating on the fiber bottom electrode effectively reduces contact resistance and improves the electric field uniformity of the high-curvature interface, allowing more luminescent particles to be effectively excited by the electric field and emit light, thereby enhancing the luminous brightness. Therefore, the luminous fiber can achieve a brightness of 127 cd / m² under 36V / 2kHz AC drive. 2 The brightness is 46 cd / m² at 24V / 2kHz. 2 It features a human-safe voltage drive, which improves wearable safety while reducing power consumption.

[0006] The method for preparing high-performance luminescent fibers provided by this invention comprises the following specific steps:

[0007] Step (1): Preparation of conductive slurry. The resin is heated and dissolved in a solvent to obtain an organic carrier. Then, conductive substances and additives are added, and the slurry is obtained after thorough ball milling.

[0008] Furthermore, the resin is one or more of polyurethane, ethylene-vinyl acetate copolymer, acrylic resin, silicone resin, polyvinylidene fluoride resin, and epoxy resin;

[0009] The solvents that can be used include one or more of water, N-methylpyrrolidone, N,N-dimethylformamide, terpineol, diethylene glycol butyl ether, and diethylene glycol butyl ether acetate. The solid content of the resin is 10-50 wt%, preferably 12.5-35 wt%.

[0010] Further, the conductive material is one of carbon nanotubes, MXene, silver nanowires, polyaniline, silver nanoparticles, polyethylene dioxythiophene, and graphite. The conductive material accounts for 40-90 wt% of the conductive paste, preferably 50-80 wt%.

[0011] Furthermore, the additive is one or more of the following: silane coupling agent, titanate coupling agent, polyvinylpyrrolidone, polyamine crosslinking agent, fluorocarbon compound, sodium dodecylbenzenesulfonate, carboxymethyl cellulose, and polyether silicone oil.

[0012] Furthermore, the ball-to-material ratio in the ball milling process is 1:1-5:1, preferably 2:1-4:1; the ball milling speed is 50-400 rpm, preferably 100-300 rpm.

[0013] Step (2): Preparation of conductive fibers. The conductive slurry from step (1) is coated onto the surface of textile fibers to obtain conductive fibers with a conductive layer, which can be used as the fiber bottom electrode. The fiber conductivity can reach up to 4.2 × 10⁻⁶. 4 S / cm.

[0014] Furthermore, the textile fiber includes one of polyamide fiber, aramid fiber, spandex fiber, polyester fiber, acrylic fiber, polyethylene fiber, or polyvinyl chloride fiber. The polymer fiber has a diameter of 50-200 μm, preferably 80-170 μm, and has a multifilament structure.

[0015] Furthermore, the coating speed of the conductive paste is 2-10 m / min, and the drying temperature is 80-220℃, preferably 4-8 m / min and 100-200℃, respectively.

[0016] Furthermore, the conductive layer has a load thickness of 10-80 μm, preferably 25-65 μm.

[0017] Step (3): Loading dielectric and light-emitting layers. Dissolve the polymer in a solvent to obtain a polymer solution, and add inorganic ceramic powder and electroluminescent powder respectively to prepare dielectric paste and light-emitting paste; coat the two pastes sequentially on the surface of the conductive layer of the conductive fiber, and load the dielectric layer and light-emitting layer sequentially.

[0018] Furthermore, the polymer is one of polyvinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-vinylidene chloride copolymer, cyano resin, and cyanoethyl cellulose;

[0019] Further, the solvent is N,N-dimethylformamide, methyl isobutyl ketone, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, or propylene glycol diacetate, and the polymer solid content is 10-50 wt%, preferably 15-35 wt%.

[0020] Furthermore, the inorganic ceramic powder comprises one of titanium dioxide, zirconium dioxide, silicon dioxide, barium titanate, aluminum oxide, and silicon nitride; the average particle size of the ceramic material is 50nm-5μm, preferably 100nm-3μm; the mass ratio of ceramic powder to polymer is 1:1-4:1 ((1-4):1), preferably 2:1-3.5:1 ((2-3.5):1).

[0021] Furthermore, the electroluminescent active material is a zinc sulfide (ZnS)-based electroluminescent material, and the doping elements include one or more of Cu, Al, Ag, Cl, and Mn. The average particle size of the electroluminescent active material is 0.5 μm-10 μm, preferably 1-5 μm; the mass ratio of electroluminescent powder to polymer is (2-8):1, preferably 3:1-5:1.

[0022] Furthermore, the centrifugal degassing stirring speed of the dielectric paste and the luminescent paste is set to 500-3000 rpm, preferably 1000-2200 rpm.

[0023] Furthermore, the coating speed of the dielectric paste and the luminescent paste is 5-20 m / min, preferably 8-16 m / min; the drying temperature is 120-250℃, preferably 150-230℃.

[0024] Furthermore, the dielectric layer load thickness is 10-50 μm, preferably 15-40 μm; the light-emitting layer load thickness is 10-80 μm, preferably 20-60 μm.

[0025] Then, a fiber external electrode is wound around the surface of the light-emitting layer to obtain a light-emitting fiber.

[0026] Step (4): Simulate the nacreous structure of a seashell and encapsulate it by sequentially designing alternating "soft-hard" interface layers on the surface of the luminescent fiber. The materials used are high-adhesion waterborne polyurethane (soft), modified smooth polyurethane (hard), fluorocarbon polyurethane (soft), and polyethylene (hard).

[0027] The preparation process is as follows: First, an anionic, highly adhesive waterborne polyurethane emulsion is coated onto the surface of the luminescent fiber, and a corresponding crosslinking agent for the anionic polyurethane is added, controlling the coating thickness to 10-15 μm; then, a modified smooth polyurethane emulsion is coated, and a corresponding crosslinking agent for the smooth polyurethane is added, controlling the coating thickness to 15-20 μm; next, a waterborne fluorocarbon polyurethane emulsion is coated, and a corresponding crosslinking agent for the fluorocarbon polyurethane is added, controlling the coating thickness to 10-15 μm; finally, polyethylene solid resin is melt-coated, and a polyethylene crosslinking agent is added, controlling the coating thickness to 20-30 μm. The solid content of each of the above functional emulsions is 20%-60%, the amount of crosslinking agent is 1%-5% of the functional emulsion, the crosslinking temperature is 120-200℃, and the coating speed is 5-20 m / min. Through the rational design of each functional coating, high protective properties and service durability can be achieved synergistically.

[0028] Optical performance testing showed that the luminescent fiber prepared by this invention achieved a brightness of 127 cd / m² at 36V / 2kHz. 2 The brightness is 46 cd / m² at 24V / 2kHz. 2 This means that the indoor display function is maintained under a safe voltage for the human body, improving wearable safety. If the driving voltage is increased, the luminous intensity can reach 1863 cd / m² under a 110V / 2kHz AC drive. 2 It can meet the requirements for use in high-light outdoor environments.

[0029] Durability tests showed that the luminescent fiber prepared by this invention maintained over 90% of its luminescence brightness after 20,000 180° bends, with uniform luminescence. After washing the fiber 100 times according to industrial washing standard AATCC61:2013-2A, the luminescence brightness remained above 80%. After repeated rubbing under 9N pressure for 100,000 cycles, the colorfastness grade was 4-5, and the brightness was over 85% of the initial brightness. Immersing the fiber in deionized water, industrial ethanol, acetone solvent, artificial sweat, NaOH solution (pH=12), and hydrochloric acid solution (pH=1) for 7 days showed no peeling of the surface coating, normal luminescence, and a brightness maintained above 90%. After freezing the fiber in ice for 24 hours and placing it in boiling water at 100℃ for 2 hours, the luminescence remained normal, with a brightness above 90% of the initial brightness. A photoaging test in a xenon lamp aging chamber showed that the fiber's colorfastness grade was four, and the brightness was 80% of the initial brightness. By weaving, embroidering, and knitting luminescent fibers, a yield rate of over 95% can be achieved, resulting in luminescent fabrics with uniform luminescence and no brightness loss.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) In this invention, textile fibers are used as the substrate, and the fiber bottom electrode obtained by coating a conductive layer has high flatness, avoiding the electric field concentration effect on the surface of high-curvature fibers, and has a flatness of up to 4.2 × 10⁻⁶. 4 The conductivity of S / cm significantly improves the luminous brightness of the light-emitting fiber and reduces the driving voltage. The brightness within a safe voltage of 36V can meet the display application requirements under indoor illuminance, improves wearable safety, and reduces the power consumption of the light-emitting fiber.

[0032] (2) A shell-like nacreous layer structure was designed on the surface of the luminescent fiber, and a uniform, dense, and durable encapsulation and protective coating was prepared by combining it with thermosetting crosslinking technology. The resulting luminescent fiber has excellent resistance to mechanical friction, solvents, acids and alkalis, heat aging, light aging, and weaving, which effectively improves the stability of use and can better meet the needs of outdoor and various application scenarios. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the luminescent fiber of the present invention.

[0034] Figure 2 This is a flowchart illustrating the preparation method of the present invention.

[0035] Figure 3 This is a brightness-voltage curve of the luminescent fiber of the present invention.

[0036] Figure 4 (a) shows the process of embroidering the luminescent fibers of the present invention into fabric; (b) shows a real object of the luminescent fiber woven bracelet lit up under a safe voltage of 36V / 2kHz.

[0037] Figure 5 (a) The bending resistance test of the luminescent fiber of the present invention is 180° and the number of bends is 20,000; (b) The industrial washing resistance test of the luminescent fabric is 100 times. The washing standard is AATCC61:2013-2A. The washing conditions are: soap concentration 0.15wt%, 50 6mm steel balls, washing temperature 49℃, washing time 49min / time, and a total of 100 times.

[0038] Figure 6 The abrasion resistance test of the luminescent webbing woven from the luminescent fibers of this invention was conducted according to the standard GB / T 3920-2008 "Textiles - Tests for color fastness to rubbing", with the test conditions being a friction pressure of 9N and 100,000 cycles.

[0039] Figure 7 This invention relates to a test of the lightfastness of the luminescent fiber. Test standard: GB / T 8427-2008 "Textiles - Tests for colorfastness to artificial light: Xenon arc", test conditions: blackboard temperature 65℃, light intensity 1.15 W / m².2 The light exposure lasted for 14 days, and the total energy was 450 kJ.

[0040] Figure 8 The luminescent fibers or luminescent fabrics of this invention are tested for resistance to extreme temperatures, solvents, and acids and alkalis. (a) The luminescent fibers are boiled in water for 2 hours; (b) The luminescent fabrics are frozen in ice for 24 hours; (c) The luminescent fibers are soaked in various solvents and solutions (including ethanol, acetone, artificial sweat, sodium hydroxide solution with pH=12, and hydrochloric acid solution with pH=1) for 7 days.

[0041] Figure 9 For the abrasion resistance test of the luminescent webbing woven from the luminescent fibers prepared in the comparative example, the test standard was GB / T3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing", and the test conditions were: friction pressure 9N, 500 cycles. Detailed Implementation

[0042] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0043] All reagents used in the following examples are commercially available, and all equipment is commercially available.

[0044] Example 1: Fabrication and functional testing of high-performance blue light-emitting fibers driven by a safe voltage;

[0045] The specific preparation steps are as follows:

[0046] (1) Prepare conductive slurry: Dissolve thermoplastic polyurethane in N-methylpyrrolidone at a solid content of 20 wt%. Heat and stir in a water bath at 60°C until cooled to obtain a polyurethane solution. Add silver particles with an average particle size of 600 nm at a solid content of 70 wt% to the polyurethane solution, and then add 2 wt% of silane coupling agent KH550. After ball milling, the conductive slurry is obtained with a ball-to-material ratio of 2:1 and a ball milling speed of 200 rpm.

[0047] (2) A conductive paste was coated and loaded onto aramid fiber multifilaments to serve as the fiber bottom electrode; the coating speed was set to 5 m / min, the drying temperature to 150℃, and the conductive layer thickness to 30 μm. The fiber conductivity was 8.7 × 10⁻⁶. 3 S / cm.

[0048] (3) Polyvinylidene fluoride-vinylidene chloride resin was dissolved in N,N-dimethylformamide with a solid content of 15wt%, and the polymer solution was obtained by heating, stirring and cooling in a water bath at 60°C.

[0049] Titanium dioxide powder with an average particle size of 500 nm was added to the polymer solution at a mass ratio of 2:1. The mixture was centrifuged and degassed at a stirring speed of 1200 rpm for 5 minutes to obtain a dielectric paste.

[0050] Cu-doped ZnS electroluminescent material with an average particle size of 0.5 μm was added to the polymer solution at a mass ratio of 3:1. The mixture was centrifuged and degassed at a stirring speed of 1600 rpm for 5 minutes to obtain the luminescent slurry.

[0051] (4) Turn on the coating device and load the dielectric paste and luminescent paste onto the fiber bottom electrode in sequence. Set the coating rate to 7m / min, the drying temperature to 170℃, the dielectric layer thickness to 35μm, and the luminescent layer thickness to 30μm. After winding, wrap the conductive fiber as the outer electrode to obtain the luminescent fiber.

[0052] (5) The surface of the luminescent fiber prepared in step (4) is coated with an anionic high-adhesion waterborne polyurethane emulsion with a solid content of 20%, and 1% of the corresponding anionic polyurethane crosslinking agent is added. The crosslinking temperature is 120℃, the coating speed is 5m / min, and the coating thickness is 10μm. Then, a modified smooth polyurethane emulsion with a solid content of 40% is coated, and 3% of the corresponding smooth polyurethane crosslinking agent is added, controlling the coating thickness to 12μm. Next, a waterborne fluorocarbon polyurethane emulsion with a solid content of 35% is coated, and 4% of the corresponding fluorocarbon polyurethane crosslinking agent is added, controlling the coating thickness to 10μm. Finally, polyethylene solid resin is melt-coated, and 4% of polyethylene crosslinking agent is added. The melting and crosslinking temperature is 150℃, the stretching speed is 10m / min, and the coating thickness is controlled to 25μm. Thus, a high-performance luminescent fiber is obtained.

[0053] Functional testing:

[0054] The luminescence of the fiber device was tested using a hyperspectral camera, and the luminescence-voltage variation curve is shown below. Figure 3 As shown, the brightness is 82 cd / m² at 36V / 2kHz. 2 The brightness is 31 cd / m² at 24V / 2kHz. 2 At 110V / 2kHz, the brightness is over 1500 cd / m². 2 The emitted light is blue.

[0055] Then, the fiber device is embroidered and woven. The weaving process is smooth, and the resulting Fudan logo pattern can achieve uniform and stable light emission. Figure 4 a) Further weaving the luminescent fibers into a bracelet, the wearing effect under a safe voltage of 36V / 2kHz is as follows Figure 4 As shown in b, it emits bright and uniform light under indoor illumination. A bending resistance test was conducted on the luminescent fiber, and the results are as follows: Figure 5As shown in Figure a, the luminescent fiber retains over 90% of its luminescence brightness after 20,000 180° bending tests, and the luminescence is uniform. After washing the luminescent fiber 100 times according to industrial washing standard AATCC61:2013-2A, the luminescence brightness remains above 80%. Figure 5 b).

[0056] Example 2: Fabrication and Functional Testing of High-Performance Green Light-Emitting Fiber Driven by Safe Voltage

[0057] The specific preparation steps are as follows:

[0058] (1) To prepare the conductive paste, ethylene-vinyl acetate copolymer was dissolved in terpineol at a solid content of 30 wt%. After heating and stirring in a water bath at 60°C and cooling, an ethylene-vinyl acetate copolymer solution was obtained. Silver nanowires and Mxene were added to the ethylene-vinyl acetate copolymer solution at solid contents of 20 wt% and 45 wt%, respectively. Then, 3 wt% of polyether silicone oil leveling agent and 1 wt% of hexamethylenediamine were added. After ball milling, the conductive paste was obtained with a ball-to-material ratio of 1.5:1 and a ball milling speed of 250 rpm.

[0059] (2) A conductive paste was coated onto polyamide fibers to serve as the fiber bottom electrode. The coating speed was set to 8 m / min, the drying temperature to 120 °C, and the conductive layer thickness to 45 μm. The fiber conductivity was 4.2 × 10⁻⁶. 4 S / cm.

[0060] (3) The polyvinylidene fluoride propylene-hexafluoropropylene copolymer was dissolved in methyl isobutyl ketone with a solid content of 17.5 wt%, and the polymer solution was obtained by heating, stirring and cooling in a water bath at 60°C.

[0061] Silica powder with an average particle size of 1 μm was added to the polymer solution at a mass ratio of 3:1 and stirred until homogeneous to obtain a dielectric paste. The paste was then centrifuged and degassed at a speed of 1600 rpm for 5 minutes to obtain the dielectric paste.

[0062] Electroluminescent active materials doped with Cu and Al elements with an average particle size of 5 μm were added to the polymer solution at a mass ratio of 3:1. The mixture was centrifuged and degassed at a stirring speed of 1800 rpm for 5 min to obtain the luminescent paste.

[0063] (4) Turn on the coating device and load the dielectric paste and luminescent paste onto the fiber bottom electrode in sequence. Set the coating rate to 10m / min, the drying temperature to 200℃, the dielectric layer thickness to 25μm, and the luminescent layer thickness to 40μm. After winding, wrap the conductive fiber as the outer electrode to obtain the ultra-high brightness luminescent fiber.

[0064] (5) The surface of the luminescent fiber prepared in step (4) is coated with an anionic high-adhesion waterborne polyurethane emulsion with a solid content of 40%, and 3% of the corresponding anionic polyurethane crosslinking agent is added. The crosslinking temperature is 150℃, the coating speed is 10m / min, and the coating thickness is 12μm. Then, a modified smooth polyurethane emulsion with a solid content of 20% is coated, and 1% of the corresponding smooth polyurethane crosslinking agent is added, controlling the coating thickness to 10μm. Next, a waterborne fluorocarbon polyurethane emulsion with a solid content of 60% is coated, and 5% of the corresponding fluorocarbon polyurethane crosslinking agent is added, controlling the coating thickness to 12μm. Finally, polyethylene solid resin is melt-coated, and 5% of polyethylene crosslinking agent is added. The melting and crosslinking temperature is 200℃, the stretching speed is 15m / min, and the coating thickness is controlled to 30μm. Thus, a high-performance luminescent fiber is obtained.

[0065] Functional testing:

[0066] The luminescence intensity was measured using a hyperspectral camera, and the luminescence intensity of the fabricated fiber optic device was 127 cd / m² at 36V / 2kHz. 2 The brightness is 46 cd / m² at 24V / 2kHz. 2 The brightness is 1863 cd / m² at 110V / 2kHz. 2 The emitted light is green.

[0067] After the luminescent fibers were repeatedly rubbed 100,000 times under 9N pressure according to the national standard GB / T 3920-2008, the color fastness grade was 4-5, and the brightness was 90% of the initial brightness. Figure 6 The luminescent fibers were subjected to xenon lamp aging color fastness testing according to the national standard GB / T 8427-2008, and the results are as follows. Figure 7 As shown, the color fastness grade is 4, and the luminescence is normal.

[0068] Example 3: Fabrication and Functional Testing of High-Performance Orange-Light-Emitting Fiber Driven by Safe Voltage

[0069] Specific preparation steps:

[0070] (1) To prepare the conductive slurry, silicone resin was dissolved in diethylene glycol butyl ether at a solid content of 20 wt%. The solution was heated and stirred in an 80°C water bath until cooled to obtain a silicone resin solution. Graphene was added to the silicone resin solution at a solid content of 75 wt%, followed by 2.5 wt% KH560 and 1 wt% carboxymethyl cellulose. The conductive slurry was obtained after ball milling at a ball-to-material ratio of 3:1 and a ball milling speed of 150 rpm.

[0071] (2) A conductive paste was loaded onto aramid fibers to serve as the fiber bottom electrode. The coating speed was set to 4 m / min, the drying temperature to 200℃, and the conductive layer thickness to 60 μm. The fiber conductivity was 2.6 × 10⁻⁶.4 S / cm.

[0072] (3) Dissolve cyanoethyl cellulose in propylene glycol diacetate with a solid content of 20 wt%, heat and stir in a water bath at 60°C to obtain a polymer solution, add barium titanate powder with an average particle size of 100 nm to the polymer solution at a mass ratio of 2.5:1, centrifuge and degas at a stirring speed of 2000 rpm, and stir for 5 min to obtain dielectric paste.

[0073] Electroluminescent active materials doped with Cu and Mn elements with an average particle size of 10 μm were added to the polymer solution at a mass ratio of 5:1. The mixture was centrifuged and degassed at a stirring speed of 2200 rpm for 5 min to obtain the luminescent slurry.

[0074] (4) Turn on the coating device and load the dielectric paste and luminescent paste onto the fiber bottom electrode in sequence. Set the coating rate to 8m / min, the drying temperature to 190℃, the dielectric layer thickness to 20μm, and the luminescent layer thickness to 25μm. After winding, wrap the conductive fiber as the outer electrode to obtain the luminescent fiber.

[0075] (5) The surface of the luminescent fiber prepared in step (4) is coated with an anionic high-adhesion waterborne polyurethane emulsion with a solid content of 60%, and 5% of the corresponding anionic polyurethane crosslinking agent is added. The crosslinking temperature is 200℃, the coating speed is 20m / min, and the coating thickness is 15μm. Then, a modified smooth polyurethane emulsion with a solid content of 60% is coated, and 5% of the corresponding smooth polyurethane crosslinking agent is added, controlling the coating thickness to 15μm. Next, a waterborne fluorocarbon polyurethane emulsion with a solid content of 20% is coated, and 1% of the corresponding fluorocarbon polyurethane crosslinking agent is added, controlling the coating thickness to 15μm. Finally, polyethylene solid resin is melt-coated, and 1% of polyethylene crosslinking agent is added. The melting and crosslinking temperature is 120℃, the stretching speed is 20m / min, and the coating thickness is controlled to 20μm. Thus, a high-performance luminescent fiber is obtained.

[0076] Functional testing:

[0077] The luminescence intensity was measured using a hyperspectral camera, and the luminescence intensity of the fabricated fiber optic device was 10⁵ cd / m² at 36V / 2kHz. 2 The brightness is 36 cd / m² at 24V / 2kHz. 2 The brightness is 1579 cd / m² at 110V / 2kHz. 2 The emitted light is orange.

[0078] The luminescent fibers or woven luminescent fabrics are subjected to tests for resistance to extreme temperatures, solvents, and acids and alkalis. For example... Figure 8As shown in a, when the luminescent fiber is placed in water and boiled for 2 hours under the illumination state of 36V / 2kHz, its luminescence is uniform and stable, with no short circuit or open circuit. Figure 8 b) The luminescent fabric was frozen in ice for 24 hours and then lit at 36V / 2kHz, and it still emitted light uniformly and stably. Figure 8 c) The luminescent fiber was soaked in various solvents and solutions (including ethanol, acetone, artificial sweat, sodium hydroxide solution with pH=12, and hydrochloric acid solution with pH=1) for 7 days, and then lit up at 36V / 2kHz, and it could still emit light continuously and uniformly.

[0079] Comparative Example 1

[0080] The conductive fibers in steps (1) and (2) of Example 3 were replaced with commercially available 0.2 mm diameter copper wires. Then, the luminescent fibers were prepared according to the process in steps (3) and (4). The nacreous structure design of the shell in step (5) was not used. Instead, a 30 μm thick PTFE protective layer was coated to prepare the luminescent fibers.

[0081] The luminescence of the fiber device was tested using a hyperspectral camera. The results showed that the luminescence of the fiber was only 5 cd / m² at 36V / 2kHz. 2 The luminescence is only visible in complete darkness. When the luminescent fibers were woven into a tape and subjected to abrasion resistance testing, the surface encapsulation layer peeled off after 500 cycles, exposing the outer fiber electrodes. Figure 9 Further friction caused the outer electrode to break. The luminescent fiber was then placed in room temperature water for a lighting test; after 0.5 hours, a short circuit occurred, and the fiber stopped lighting up. When the luminescent fiber was placed in an industrial ethanol solution, the surface coating dissolved in the ethanol after 20 minutes, and a short circuit occurred between the internal electrodes, causing the fiber to stop lighting up.

[0082] In summary, the luminescent fibers prepared by this invention can be driven to emit light under human-safe voltages of 36V and 24V. Furthermore, the luminescent fibers possess both good flexibility and durability, and can be further woven into multifunctional electronic fabrics to meet the needs of various application scenarios requiring wearable safety.

Claims

1. A method for preparing a high-performance luminescent fiber driven by a safe voltage, characterized in that, The luminescent fiber structure consists of, from the inside out, a cylindrical conductive fiber bottom electrode, a dielectric layer, a luminescent layer, an outer fiber electrode, and a shell-like pearl encapsulation layer. The specific fabrication steps are as follows: Step (1): Prepare conductive slurry; Dissolve the resin in a solvent by heating to obtain an organic carrier, then add conductive substances and additives, and obtain conductive slurry after thorough ball milling; Step (2): Prepare conductive fibers; The conductive paste prepared in step (1) is coated onto the surface of textile fibers to obtain conductive fibers with a conductive layer, which serve as the fiber bottom electrode; the fiber conductivity reaches a maximum of 4.2 × 10⁻⁶. 4 S / cm; Step (3): Loading dielectric layer and light-emitting layer; dissolve polymer in solvent to obtain polymer solution, add inorganic ceramic powder and electroluminescent powder respectively to prepare dielectric paste and light-emitting paste; coat the two pastes sequentially on the conductive layer surface of conductive fiber to form dielectric layer and light-emitting layer in sequence; then wind fiber external electrode around the surface of light-emitting layer to obtain light-emitting fiber; Step (4): Simulate the nacreous structure of a seashell, and encapsulate the surface of the luminescent fiber with alternating "soft-hard" interface layers to form a simulated seashell pearl encapsulation layer; the materials used are soft high-adhesion waterborne polyurethane, hard modified smooth polyurethane, soft fluorocarbon polyurethane, and hard polyethylene.

2. The preparation method according to claim 1, characterized in that, In step (1): The resin is selected from polyurethane, ethylene-vinyl acetate copolymer, acrylic resin, silicone resin, polyvinylidene fluoride resin, and epoxy resin; The solvent is selected from water, N-methylpyrrolidone, N,N-dimethylformamide, terpineol, diethylene glycol butyl ether, and diethylene glycol butyl ether acetate; The conductive material is selected from one of carbon nanotubes, MXene, silver nanowires, polyaniline, silver nanoparticles, polyethylene dioxythiophene, and graphite. In conductive pastes, the solid content of resin is 10-50 wt%, and the content of conductive material is 40-90 wt%.

3. The preparation method according to claim 2, characterized in that, In step (1): The additives are selected from silane coupling agents, titanate coupling agents, polyvinylpyrrolidone, polyamine crosslinking agents, fluorocarbon compounds, sodium dodecylbenzene sulfonate, carboxymethyl cellulose, and polyether silicone oil; During the ball milling process, the ball-to-material ratio is 1:1 to 5:1; the ball milling speed is 50 to 400 rpm.

4. The preparation method according to claim 1, characterized in that, In step (2): The textile fiber is selected from one of polyamide fiber, aramid fiber, spandex fiber, polyester fiber, acrylic fiber, polyethylene fiber and polyvinyl chloride fiber; the fiber diameter is 50-200 μm and the structure is monofilament or multifilament; The coating speed of the conductive paste is 2-10 m / min, and the drying temperature is 80-220 ℃; The thickness of the conductive layer is 10-80 μm.

5. The preparation method according to claim 1, characterized in that, In step (3): The polymer is selected from one of polyvinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-vinylidene chloride copolymer, cyano resin, and cyanoethyl cellulose; The solvent is selected from N,N-dimethylformamide, methyl isobutyl ketone, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, or propylene glycol diacetate, and the concentration of the polymer solution is 10-50 wt%. The inorganic ceramic powder is selected from one of titanium dioxide, zirconium dioxide, silicon dioxide, barium titanate, aluminum oxide, and silicon nitride; the average particle size of the ceramic material is 50 nm-5 μm; the mass ratio of ceramic powder to polymer is (1-4):1; The electroluminescent powder is a zinc sulfide-based electroluminescent material, and the doping elements are selected from Cu, Al, Ag, Cl, and Mn; the average particle size of the electroluminescent powder is 0.5 μm-10 μm; the mass ratio of the electroluminescent powder to the polymer is (2-8):

1.

6. The preparation method according to claim 5, characterized in that, In step (3): The centrifugal degassing stirring speed of the dielectric paste and the luminescent paste is set to 500-3000 rpm; The coating speed of the dielectric paste and the luminescent paste is 5-20 m / min; the drying temperature is 120-250 ℃; The dielectric layer has a thickness of 10-50 μm; the light-emitting layer has a thickness of 10-80 μm.

7. The preparation method according to claim 1, characterized in that, The preparation process of the imitation seashell pearl encapsulation layer in step (4) is as follows: First, an anionic high-adhesion waterborne polyurethane emulsion is coated on the surface of the luminescent fiber, and the corresponding crosslinking agent of the anionic polyurethane is added to control the coating thickness to 10-15 μm; then, a modified smooth polyurethane emulsion is coated, and the corresponding crosslinking agent of the smooth polyurethane is added to control the coating thickness to 15-20 μm; then, a waterborne fluorocarbon polyurethane emulsion is coated, and the corresponding crosslinking agent of the fluorocarbon polyurethane is added to control the coating thickness to 10-15 μm; finally, a polyethylene solid resin is melt-coated, and a polyethylene crosslinking agent is added to control the coating thickness to 20-30 μm; the solid content of each of the above functional emulsions is 20%-60%, the amount of crosslinking agent is 1%-5% of the functional emulsion, the crosslinking temperature is 120-200 ℃, and the coating speed is 5-20 m / min.

8. A high-performance luminescent fiber driven by a safe voltage, obtained by the preparation method according to any one of claims 1-7.

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