High-performance luminescent fiber driven by safe voltage and preparation method of high-performance luminescent fiber

Abstract

The invention belongs to the technical field of functional textile fibers, and particularly relates to a high-performance luminescent fiber driven by safe voltage and a preparation method of the high-performance luminescent fiber. The light-emitting fiber sequentially comprises a cylinder-like conductive fiber electrode, a dielectric layer, a light-emitting layer, an outer fiber electrode and a shell-imitated pearl packaging layer from inside to outside, the preparation process comprises the following steps: loading conductive slurry to the surface of textile fiber through coating to obtain conductive fiber with a conductive layer; a load dielectric layer and a light emitting layer; winding a fiber external electrode on the surface of the luminous layer; simulating a shell nacreous layer structure, and forming a packaging layer on the surface of the luminous fiber; the packaging layer has excellent performances of mechanical friction resistance, thermal aging resistance and the like. According to the invention, the electric field uniformity of a high-curvature interface is improved, more light-emitting particles are excited by an effective electric field to emit light, so that the light-emitting brightness is improved, the brightness can reach 127cd / m < 2 > under the driving of 36V / 2kHz alternating current, the characteristic of human body safety voltage driving is realized, the wearable safety is improved, and meanwhile, the power consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional textile fibers, and in particular relates to a high-performance luminescent fiber driven by a safe voltage and a preparation method thereof. Background Art

[0002] Due to its excellent flexibility, electroluminescent fibers can be used to construct soft and breathable luminous fabrics through various weaving methods, showing unique advantages in wearable devices. DC electroluminescent fibers such as OLED luminous fibers, PLED luminous fibers, and QLED luminous fibers, because the device contains hole and electron transport layers, holes and electrons can be directly injected into the luminescent layer to combine and produce luminescence. Its luminescence principle determines its high luminescence efficiency. However, the luminescence principle of AC electroluminescent devices is that under the action of an AC electric field, positive and negative charge carriers are repeatedly accelerated and collide with the luminescent center under the reversed electric field to emit light. This involves issues such as the frequency of the AC electric field and the AC coupling energy loss, and has the characteristics of high driving voltage and low brightness.

[0003] However, the preparation conditions of DC electroluminescent fibers are relatively stringent, requiring a clean environment without water or oxygen, with high requirements for film flatness. At the same time, strict water and oxygen isolation packaging is required to ensure a certain luminous life. AC electroluminescent fibers, on the other hand, have slightly lower requirements for film flatness, good water and oxygen resistance, and do not require strict packaging, which reduces the difficulty of flexible fiber packaging. Therefore, compared with DC electroluminescent fibers, AC electroluminescent fibers are easier to achieve large-scale continuous preparation. Currently, the mainstream and more mature fiber-light-emitting devices still use AC electroluminescent materials. However, achieving a performance breakthrough in luminous brightness is a key requirement for such devices to move towards practical application, especially to meet the normal display function under high illumination conditions. At present, zinc sulfide luminescent powder based on the principle of field luminescence is the core active material of alternating current electroluminescent fiber. Its advantage is that it can be prepared on a large scale through a continuous process, and the resulting luminescent fiber has the characteristics of thin diameter, good flexibility, and easy weaving, as described in patents CN202210444431.1, CN202210568318.4, and CN202111312835.7. However, the current luminescent fibers face the problems of low luminous brightness, high driving voltage, and difficulty in application outdoors or in high-illuminance environments, which is a technical bottleneck that urgently needs to be broken through in this field. In addition, the current patent reports and electroluminescent fibers available on the market mainly focus on luminous performance and color changes. The surface protective coating materials have not been designed with emphasis, and are faced with defects such as mechanical friction resistance, solvent resistance, and weather resistance, making it difficult to adapt to actual application needs. Summary of the Invention

[0004] The object of the present invention is to provide a high-performance luminescent fiber that can be driven at a safe voltage within 36V and a preparation method thereof.

[0005] The high-performance luminescent fiber provided by the present invention has the following structural components: from the inside to the outside: a cylindrical conductive fiber electrode, a dielectric layer, a luminescent layer, an outer fiber electrode, and a shell pearl-like encapsulation layer; Figure 1 The preparation process is as follows: first, a resin is dissolved in a solvent to obtain an organic carrier. Then, a conductive material and a conductive additive are added to the organic carrier and thoroughly ball-milled to obtain a high-performance conductive slurry. The conductive slurry is applied between textile fiber bundles and on the fiber surface by coating to form a conductive layer, resulting in a highly flat, highly conductive fiber bottom electrode. Then, an inorganic ceramic powder and an electroluminescent active material are added to the polymer solution, and after centrifugal degassing and stirring, a dielectric slurry and a luminescent slurry are obtained, respectively. The dielectric slurry and the electroluminescent active slurry are sequentially applied to the surface of the conductive fiber by coating, and then the conductive fiber is wound around as an external electrode to prepare the luminescent fiber. Finally, a "soft-hard" alternating interface layer is designed on the surface of the luminescent fiber, mimicking the structure of the nacre layer. The layer is then thermally cross-linked using a corresponding cross-linking agent to form a uniform, dense, and durable encapsulation protective coating. The coating exhibits excellent resistance to mechanical friction, solvents, acids and alkalis, heat aging, light aging, and weaving. At the same time, the uniform and smooth conductive coating of the fiber bottom electrode effectively reduces the contact resistance and improves the electric field uniformity of the high-curvature interface, so that more luminescent particles can be effectively excited by the electric field and emit light, thereby improving the luminous brightness. Therefore, the brightness of the luminescent fiber can reach 127cd / m2 when driven by 36V / 2kHz AC. 2 , the brightness is 46cd / m at 24V / 2kHz 2 , with the characteristics of human body safe voltage drive, which improves wearable safety while reducing power consumption.

[0006] The preparation method of the high-performance luminescent fiber provided by the present invention comprises the following specific steps:

[0007] Step (1): Prepare conductive paste. Heat and dissolve the resin in a solvent to obtain an organic carrier, then add a conductive substance and an auxiliary agent, and fully ball mill to obtain a conductive paste.

[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 10-50wt%, preferably 12.5-35wt%.

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

[0011] Furthermore, the auxiliary agent is a mixture of one or more of silane coupling agent, titanate coupling agent, polyvinyl pyrrolidone, polyamine crosslinking agent, fluorocarbon compound, sodium dodecylbenzene sulfonate, 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; and the ball milling speed is 50-400 rpm, preferably 100-300 rpm.

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

[0014] Furthermore, the textile fiber comprises 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° C., preferably 4-8 m / min and 100-200° C., respectively.

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

[0017] Step (3): Loading the dielectric layer and the luminescent layer. Dissolve the polymer in a solvent to obtain a polymer solution, add inorganic ceramic powder and electroluminescent powder respectively, to prepare dielectric slurry and luminescent slurry; apply the two slurries sequentially to the conductive layer surface of the conductive fiber, and load the dielectric layer and luminescent layer in sequence.

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

[0019] Furthermore, the solvent is N,N-dimethylformamide, methyl isobutyl ketone, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran or propylene glycol diacetate, and the solid content of the polymer 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 50 nm-5 μm, preferably 100 nm-3 μm; 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 element comprises one or more of Cu, Al, Ag, Cl, and Mn. The average particle size of the electroluminescent active material is 0.5 μm to 10 μm, preferably 1 to 5 μm. The mass ratio of the electroluminescent powder to the polymer is (2-8):1, preferably 3:1-5:1.

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

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

[0024] Furthermore, the dielectric layer has a loading thickness of 10-50 μm, preferably 15-40 μm; the light-emitting layer has a loading thickness of 10-80 μm, preferably 20-60 μm.

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

[0026] Step (4): Simulating the structure of the nacre layer of shells, a "soft-hard" alternating interface layer is designed on the surface of the luminescent fiber for encapsulation. The materials used are high-adhesion water-based polyurethane (soft) - modified smooth polyurethane (hard) - fluorocarbon polyurethane (soft) - and polyethylene (hard).

[0027] The preparation process is as follows: First, the surface of the luminescent fiber is coated with an anionic high-adhesion water-based polyurethane emulsion and a crosslinker corresponding to the anionic polyurethane is added, with a coating thickness of 10-15μm; then, a modified smooth polyurethane emulsion is applied and a crosslinker corresponding to the smooth polyurethane is added, with a coating thickness of 15-20μm; then, a water-based fluorocarbon polyurethane emulsion is applied and a crosslinker corresponding to the fluorocarbon polyurethane is added, with a coating thickness of 10-15μm; finally, a polyethylene solid resin is melt-coated and a polyethylene crosslinker is added, with a coating thickness of 20-30μm. The solid content of each of the above functional emulsions ranges from 20% to 60%, the crosslinker dosage is 1% to 5% of the functional emulsion, the crosslinking temperature is 120-200°C, and the coating speed is 5-20m / min. Through the rational design of each functional coating, high protection and durability can be synergistically exerted.

[0028] According to the optical performance test, the luminous fiber prepared by the present invention can reach a brightness of 127cd / m at 36V / 2kHz. 2 , the brightness is 46cd / m at 24V / 2kHz 2 , that is, it can meet the indoor display function under the human body safety voltage, improving the wear safety. If the driving voltage is increased, the luminous brightness can reach 1863cd / m2 under 110V / 2kHz AC driving. 2 , which can meet the requirements of use in outdoor high illumination environments.

[0029] After durability testing, the luminescent fiber prepared by the present invention maintained a luminous brightness of more than 90% after 20,000 180° bend tests, and the luminescence was uniform. After the luminescent fiber was washed 100 times according to the industrial water washing standard AATCC61:2013-2A, the luminous brightness remained above 80%. After the luminescent fiber was repeatedly rubbed 100,000 times under 9N pressure, the color fastness grade was 4-5, and the brightness was more than 85% of the initial brightness. The luminescent fiber was immersed in deionized water, industrial ethanol, acetone solvent, artificial sweat, pH=12 NaOH solution, and pH=1 hydrochloric acid solution for 7 days. The surface coating of the luminescent fiber did not fall off, the luminescence was normal, and the brightness was maintained at more than 90%. After the luminescent fiber was frozen in ice for 24 hours and placed in 100°C boiling water for 2 hours, the luminescence was normal, and the brightness was more than 90% of the initial brightness. The luminescent fiber was subjected to a light aging test in a xenon lamp aging box. The color fastness grade of the luminescent fiber was level 4, and the brightness was 80% of the initial brightness. By weaving, embroidering and knitting luminous fibers, a yield rate of over 95% can be achieved, and the resulting luminous fabric emits light evenly without brightness loss.

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

[0031] (1) The fiber bottom electrode obtained by coating the conductive layer with the textile fiber as the substrate has a high flatness, which avoids the electric field concentration effect on the high curvature fiber surface and has a high flatness of up to 4.2×10 4 S / cm, which greatly improves the luminous brightness of the luminous fiber and significantly reduces the driving voltage. The brightness within the safety voltage of 36V can meet the display application under indoor illumination, improves the wear safety, and reduces the power consumption of the luminous fiber.

[0032] (2) A shell nacre-like structure was designed on the surface of the luminescent fiber, and combined with thermal curing and cross-linking technology, a uniform, dense, and durable encapsulation protective coating was prepared. The resulting luminescent fiber has excellent resistance to mechanical friction, solvents, acids and alkalis, heat aging, light aging, and weaving, effectively improving its stability in use and meeting the needs of outdoor and various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the luminescent fiber of the present invention.

[0034] Figure 2 It is a flow chart of the preparation method of the present invention.

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

[0036] Figure 4 (a) shows the process of embroidering the luminescent fiber into fabric according to the present invention; (b) shows a real picture of a bracelet woven with luminescent fibers lighting up at a safe voltage of 36V / 2kHz.

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

[0038] Figure 6 The friction resistance test of the luminous ribbon woven with the luminous fiber of the present invention is carried out according to the test standard: GB / T 3920-2008 "Textiles - Tests for colour fastness - Colour fastness to friction", and the test conditions are: friction pressure 9N, number of times 100,000 times.

[0039] Figure 7 This is a test of the color fastness of the luminescent fiber of the present invention to light. Test standard: GB / T 8427-2008 "Textiles - Tests for color fastness - Color fastness to artificial light: Xenon arc fading lamp", test conditions: blackboard temperature 65°C, light intensity 1.15W / m2 , lighting time 14 days, total energy 450kJ.

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

[0041] Figure 9 The friction resistance test of the luminous ribbon woven with the luminous fiber prepared in the comparative example was conducted according to the test standard: GB / T3920-2008 “Textiles—Tests for colour fastness—Colour fastness to friction”, and the test conditions were: friction pressure 9N, 500 times. DETAILED DESCRIPTION

[0042] The present invention is further described below through embodiments in conjunction with the accompanying drawings.

[0043] The reagents used in the following examples are all those of the present invention. The reagents and raw materials used are all commercially available, and the various equipment are all commercially available equipment.

[0044] Example 1, preparation and functional testing of high-performance blue light-emitting fiber driven by safe voltage;

[0045] The specific steps of preparation are:

[0046] (1) A conductive paste was prepared by dissolving thermoplastic polyurethane at a solid content of 20 wt% in N-methylpyrrolidone, heating in a 60°C water bath, stirring, and cooling to obtain a polyurethane solution. Silver particles with an average particle size of 600 nm were added to the polyurethane solution at a solid content of 70 wt%, and then 2 wt% of the total weight of a silane coupling agent, KH550, was added. The conductive paste was obtained by ball milling at a ball-to-material ratio of 2:1 and a ball milling speed of 200 rpm.

[0047] (2) The conductive slurry was coated on the aramid fiber multifilament as the fiber bottom electrode; the coating speed was set to 5 m / min, the drying temperature was set to 150 °C, and the thickness of the conductive layer was set to 30 μm. The fiber conductivity was 8.7 × 10 3 S / cm.

[0048] (3) Dissolve polyvinylidene fluoride-vinylidene chloride fluoride resin in N,N-dimethylformamide at a solid content of 15 wt%, heat in a 60° C. water bath, stir, and cool to obtain a polymer solution.

[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, and the solution was centrifuged and degassed at a stirring speed of 1200 rpm. The dielectric slurry was obtained after stirring for 5 minutes.

[0050] The 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, and the solution was centrifuged and degassed at a stirring speed of 1600 rpm. After stirring for 5 minutes, a luminescent slurry was obtained.

[0051] (4) Turn on the coating device and load the dielectric slurry and luminescent slurry on 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 external electrode to initially obtain the luminescent fiber.

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

[0053] Functional testing:

[0054] A hyperspectral camera is used to test the luminous brightness of the fiber device. The curve of brightness changing with voltage is as follows: Figure 3 As shown, the brightness is 82cd / m at 36V / 2kHz 2 , the brightness is 31cd / m at 24V / 2kHz 2 , the brightness is more than 1500 cd / m at 110V / 2kHz 2 . The luminous color is blue.

[0055] The fiber device is then embroidered and woven. The weaving process is smooth, and the resulting Fudan LOGO pattern can achieve uniform and stable luminescence ( Figure 4 a), further weaving the luminous fiber into a bracelet, the wearing effect under 36V / 2kHz safe voltage is as follows Figure 4 As shown in b, it emits bright and uniform light under indoor lighting. The luminous fiber was subjected to a bending resistance test, and the results are as follows Figure 5As shown in a, the luminous fiber maintains more than 90% luminous brightness after 20,000 times of 180° bending test, and the light is uniform. After the luminous fiber is washed 100 times according to the industrial water washing standard AATCC61:2013-2A, the luminous brightness remains above 80% ( Figure 5 b).

[0056] Example 2: Preparation and functional testing of high-performance green light-emitting fibers driven by safe voltage

[0057] The specific steps of preparation are:

[0058] (1) A conductive paste was prepared by dissolving ethylene-vinyl acetate copolymer at a solid content of 30 wt% in terpineol, heating in a 60°C water bath with stirring, and cooling to obtain an ethylene-vinyl acetate copolymer solution. Silver nanowires and MXene were added to the ethylene-vinyl acetate copolymer solution at solid contents of 20 wt% and 45 wt%, respectively. A polyether silicone oil leveling agent (3 wt% total weight) and hexamethylenediamine (1 wt% total weight) were then added. The conductive paste was obtained by ball milling at a ball-to-particle ratio of 1.5:1 and a ball milling speed of 250 rpm.

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

[0060] (3) Dissolve polyvinylidene fluoride propylene-hexafluoropropylene copolymer in methyl isobutyl ketone at a solid content of 17.5 wt %, heat in a 60° C. water bath, stir, and cool to obtain a polymer solution.

[0061] Silicon dioxide powder with an average particle size of 1 μm was added to the polymer solution at a mass ratio of 3:1, and the mixture was stirred evenly to obtain a dielectric slurry. The dielectric slurry was obtained after centrifugal degassing at a stirring speed of 1600 rpm and stirring for 5 minutes.

[0062] The electroluminescent active material doped with Cu and Al elements with an average particle size of 5 μm was added to the polymer solution at a mass ratio of 3:1, and the solution was centrifuged and degassed at a stirring speed of 1800 rpm. After stirring for 5 minutes, a luminescent slurry was obtained.

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

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

[0065] Functional testing:

[0066] The luminous brightness was tested using a hyperspectral camera. The brightness of the prepared luminous fiber device was 127cd / m at 36V / 2kHz. 2 , the brightness is 46cd / m at 24V / 2kHz 2 , the brightness is 1863cd / m at 110V / 2kHz 2 . The luminous color is green.

[0067] After the luminous fiber was 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 fiber was tested for color fastness to xenon lamp aging according to the national standard GB / T 8427-2008. The results are as follows: Figure 7 As shown, the color fastness grade is 4 and the luminescence is normal.

[0068] Example 3: Preparation and functional testing of high-performance orange light-emitting fibers driven by safe voltage

[0069] Specific steps of preparation:

[0070] (1) A conductive paste was prepared by dissolving silicone resin at a solid content of 20 wt% in diethylene glycol butyl ether, heating in an 80°C water bath with stirring, and cooling to obtain a silicone resin solution. Graphene was added to the silicone resin solution at a solid content of 75 wt%, and then 2.5 wt% of KH560 and 1 wt% of carboxymethyl cellulose were added. The conductive paste was obtained by ball milling at a ball-to-material ratio of 3:1 and a ball milling speed of 150 rpm.

[0071] (2) The conductive slurry was loaded onto the aramid fiber as the fiber bottom electrode. The coating speed was set to 4 m / min, the drying temperature was set to 200 °C, and the thickness of the conductive layer was set to 60 μm. The fiber conductivity was 2.6 × 104 S / cm.

[0072] (3) Dissolve cyanoethyl cellulose in propylene glycol diacetate at a solid content of 20 wt%, heat in a water bath at 60° C., stir, and cool 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 minutes to obtain a dielectric slurry.

[0073] The electroluminescent active material doped with Cu and Mn elements with an average particle size of 10 μm was added to the polymer solution at a mass ratio of 5:1, and the solution was centrifuged and degassed at a stirring speed of 2200 rpm. After stirring for 5 minutes, a luminescent slurry was obtained.

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

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

[0076] Functional testing:

[0077] The luminous brightness was tested using a hyperspectral camera. The brightness of the prepared luminous fiber device was 105 cd / m at 36 V / 2 kHz. 2 , the brightness is 36cd / m at 24V / 2kHz 2 , the brightness is 1579cd / m at 110V / 2kHz 2 . The luminous color is orange.

[0078] The luminous fiber or woven luminous fabric is tested for resistance to extreme temperatures, solvents, acids and alkalis. Figure 8As shown in a, the luminescent fiber was placed in water and boiled for 2 hours at 36V / 2kHz. The luminescence was uniform and stable, with no short circuit or open circuit. Figure 8 b: The luminous fabric was frozen in ice for 24 hours and then lit at 36V / 2kHz, and it still emitted light evenly and stably. Figure 8 c is to soak the luminescent fiber 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 light it up at 36V / 2kHz, and it can still continue to emit light evenly.

[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 metal copper wires, and then the luminescent fibers were prepared according to the processes of steps (3) and (4), without the shell nacre structure design of step (5). Instead, the luminescent fibers were simply coated with a 30 μm thick PTFE protective layer.

[0081] A hyperspectral camera was used to test the luminous brightness of the fiber device. The test showed that the brightness of the luminous fiber was only 5cd / m at 36V / 2kHz. 2 The luminous fiber was woven into a ribbon and subjected to a friction test. After 500 frictions, the surface encapsulation layer fell off and the outer fiber electrodes were exposed. 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 illuminating. The luminescent fiber was placed in industrial ethanol solution. After 20 minutes, the surface coating dissolved in the ethanol, causing a short circuit between the electrodes within the fiber and a failure to illuminate.

[0082] In summary, the luminescent fibers prepared by this invention can be driven to emit light at both 36V and 24V, both safe voltages for human use. Furthermore, the luminescent fibers possess excellent flexibility and durability, allowing them to be further woven into multifunctional electronic fabrics for a variety of wearable applications.

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 to the outside, a cylindrical conductive fiber bottom electrode, a dielectric layer, a luminescent layer, an outer fiber electrode, and a shell pearl-like encapsulation layer. The specific preparation steps are as follows: Step (1): preparing a conductive paste; heating and dissolving a resin in a solvent to obtain an organic carrier, then adding a conductive substance and an additive, and fully ball milling to obtain a conductive paste; Step (2): preparing conductive fibers; The conductive slurry prepared in step (1) is loaded onto the surface of the textile fiber by coating to obtain a conductive fiber having a conductive layer as a fiber bottom electrode; The fiber conductivity is as high as 4.2×10 4 S / cm; Step (3): loading a dielectric layer and a luminescent layer; dissolving a polymer in a solvent to obtain a polymer solution, adding an inorganic ceramic powder and an electroluminescent powder respectively to prepare a dielectric slurry and a luminescent slurry; coating the two slurries sequentially on the surface of the conductive layer of the conductive fiber to form a dielectric layer and a luminescent layer in sequence; then winding an external electrode of the fiber on the surface of the luminescent layer to obtain a luminescent fiber; Step (4): Simulating the structure of the shell nacre layer, the surface of the luminescent fiber is encapsulated in a "soft-hard" alternating interface layer to form an imitation shell pearl encapsulation layer; the materials used are high-adhesion water-based polyurethane (soft) - modified smooth polyurethane (hard) - fluorocarbon polyurethane (soft) - and polyethylene (hard).

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, polyethylenedioxythiophene, and graphite; In the conductive paste, the solid content of the resin accounts for 10-50wt%; the conductive material accounts for 40-90wt%.

3. The preparation method according to claim 2, characterized in that: In step (1): The auxiliary agent is selected from silane coupling agent, titanate coupling agent, polyvinyl pyrrolidone, polyamine crosslinking agent, fluorocarbon compound, sodium dodecylbenzene sulfonate, carboxymethyl cellulose, polyether silicone oil; During the ball milling process, the ball-to-material ratio is 1:1-5:1; and the ball milling speed is 50-400 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 or polyvinyl chloride fiber; the fiber has a diameter of 50-200 μm and a structure of monofilament or multifilament; The coating speed of the conductive paste is 2-10 m / min, and the drying temperature is 80-220°C; The conductive layer has a thickness of 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-chlorovinylidene fluoride copolymer, cyano resin, and cyanoethyl cellulose; The solvent is selected from N,N-dimethylformamide, methyl isobutyl ketone, N-methyl pyrrolidone, 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 the ceramic powder to the polymer is (1-4):1; The electroluminescent active material is a zinc sulfide-based electroluminescent material, and the doping element is selected from Cu, Al, Ag, Cl, and Mn; the average particle size of the electroluminescent active material is 0.5 μm-10 μm; and 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 slurry and the luminescent slurry is set to 500-3000 rpm; The coating speed of the dielectric slurry and the luminescent slurry is 5-20 m / min; the drying temperature is 120-250°C; The thickness of the dielectric layer is 10-50 μm; the thickness of the light-emitting layer is 10-80 μm; Then, a fiber outer electrode is wound on the surface of the light-emitting layer to obtain a light-emitting fiber.

7. The preparation method according to claim 1, characterized in that: The preparation process of the imitation shell pearl encapsulation layer in step (4) is as follows: first, an anionic high-adhesion water-based polyurethane emulsion is coated on the surface of the luminescent fiber, and a corresponding crosslinking agent for the anionic polyurethane is added to control 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 to control the coating thickness to 15-20 μm; then, an aqueous fluorocarbon polyurethane emulsion is coated, and a corresponding crosslinking agent for 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 the above-mentioned functional emulsions is 20%-60%, the amount of the crosslinking agent is 1%-5% of the functional emulsion, the crosslinking temperature is 120-200°C, 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 to 8.

Images