A method for preparing recycled polyester chip-based electroluminescent fibers

Abstract

This invention belongs to the field of textile and chemical fiber technology, and specifically relates to a method for preparing electroluminescent fibers based on recycled polyester chips. The steps are as follows: carbon black and clean polyester fragments are mixed and granulated to obtain conductive recycled polyester chips; the conductive recycled polyester chips are melted and processed into conductive polyester fibers using a spinning device; zinc sulfide powder is condensed on the fiber surface using a vapor deposition chamber to form a zinc sulfide film; the fibers are immersed in a polyaniline solution reaction tank for in-situ polymerization to form a robust polyaniline coating. Finally, PET-ZnS-PANI electroluminescent fibers are obtained. This method integrates melt spinning, vapor deposition, and in-situ polymerization, and is suitable for industrial mass production. The luminescent fibers have high brightness and can illuminate the filaments.

Description

Technical Field

[0001] This invention belongs to the field of textile and chemical fiber technology, and in particular relates to a method for preparing electroluminescent fibers based on recycled polyester chips. Background Technology

[0002] In recent years, emerging electroluminescent devices with flexibility and stretchability have attracted widespread attention and are considered one of the fundamental technologies for next-generation lighting and displays. Compared with rigid electroluminescent devices, stretchable electroluminescent fibers, due to their excellent mechanical flexibility, can function normally under extreme mechanical deformation, making them widely used in biomedical fields and interactive display systems. ZnS is an inexpensive, non-toxic, and environmentally friendly material with good mechanical strength, high charge carrier mobility, and an exciton binding energy of approximately 40 meV.

[0003] Patent CN111952412A discloses a method for fabricating a ZnS nanowire / graphene heterojunction photodetector. It involves depositing a ZnS nanoparticle film and Au on a graphene / SiO2 / Si substrate using an electron beam evaporation deposition system, followed by PVD growth of ZnS nanowires on the Au / ZnS nanoparticle film / graphene / SiO2 / Si to create a ZnS nanowire film / ZnS nanoparticle film / graphene / SiO2 / Si photodetector. Patent CN115666150A discloses a QWLED based on a ZnS / Cu2Se / ZnS quantum well light-emitting layer and its fabrication method. It synthesizes a ZnS / Cu2Se / ZnS cubic quantum well structure based on cubic ZnS seeds, using this as the light-emitting layer to fabricate an LED device comprising an organic hole transport layer, an inorganic electron transport layer, and a quantum well light-emitting layer. Patent CN114874582B discloses an electroluminescent material containing ZnS / Cu / BaTiO3 and its preparation method. It uses a sol-gel method to prepare high-temperature sintered BaTiO3, which is then introduced into a ZnS / Cu / epoxy resin composite material to produce an electroluminescent composite material. However, these methods use expensive materials or involve complex processes, making large-scale continuous production impossible.

[0004] Patent CN116125718A discloses an inorganic all-solid-state electrochromic device and its preparation method. It uses vacuum high-temperature evaporation to prepare an inorganic all-solid-state electrochromic film on a substrate material. However, the high-temperature evaporation requires high energy consumption and the preparation process is not suitable for continuous production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a method for preparing electroluminescent fibers based on recycled polyester chips. First, carbon black is mixed with recycled polyester chips, which are then spun into conductive polyester fibers using a melt spinning system. In the melt spinning system, the melting furnace and screw extruder are heated by a copper tube, the other end of which is connected to a vapor deposition chamber. The waste heat from the melting furnace and screw extruder powers the vapor deposition chamber, effectively avoiding energy waste. Zinc sulfide powder is placed in the vapor deposition chamber. As the conductive fibers pass through the chamber, the zinc sulfide condenses on their surface, forming a thin zinc sulfide film, which becomes the luminescent layer. Finally, the fibers are immersed in a polyaniline reaction tank for in-situ polymerization, forming a robust polyaniline conductive coating on the outer layer, resulting in PET-ZnS-PANI electroluminescent fibers. This method fully utilizes the waste heat in the melting equipment, is energy-saving and environmentally friendly, and allows for continuous industrial production.

[0006] To address the aforementioned technical problems, this application provides the following technical solution:

[0007] This invention provides a method for preparing recycled polyester chip-based electroluminescent fibers, comprising the following steps:

[0008] S1: Carbon black and recycled polyester chips (the preparation method of recycled polyester chips is referenced in [1] Chen Min. A brief discussion on the process technology of recycled bottle-grade polyester chips [J]. Zhejiang Chemical Industry, 2010, 41(10):3.DOI:10.3969 / j.issn.1006-4184.2010.10.008.) are mixed and then melted, extruded and granulated to obtain conductive recycled polyester chips;

[0009] S2: The conductive recycled polyester chips are melt-spun to obtain conductive polyester fibers;

[0010] S3: In the vapor deposition chamber, a zinc sulfide film is vapor deposited on the surface of the conductive polyester fiber and then coated with a polyaniline film to obtain the recycled polyester chip-based electroluminescent fiber (PET-ZnS-PANI).

[0011] Preferably, the carbon black content in the conductive recycled polyester chips is 10-20 wt%.

[0012] Preferably, the viscosity of the conductive recycled polyester chips is 0.68-0.88 dL / g.

[0013] Preferably, the melting temperature is 275-295℃ and the granulation temperature is 285-305℃.

[0014] Preferably, the melting is carried out in a melting furnace, and the granulation is carried out in a screw extruder. The melting furnace and the screw extruder are respectively connected to copper pipes; both the melting furnace and the screw extruder are heated through copper pipes.

[0015] Furthermore, the copper tube is also connected to the vapor deposition chamber, and the vapor deposition is heated to 265-300°C through the copper tube.

[0016] Furthermore, the copper tube is provided with a heat-insulating outer shell.

[0017] Furthermore, the cross-sectional area of ​​the copper tube is 1-2 cm². 2 It has a length of 4-5m and a thermal conductivity of 380-420W / (m·K).

[0018] Preferably, in step S1, the extrusion speed is 13-18 m / min.

[0019] Preferably, in step S2, the spinneret diameter is 150 μm during melt spinning.

[0020] Preferably, in step S2, a cooling device is provided after melt spinning, and the cooling airflow velocity of the cooling device is 600-800 m / min, and the cooling temperature is 2-30℃.

[0021] Preferably, in step S3, a vacuum treatment is performed in the vapor deposition chamber, with a pressure of 0.1 MPa.

[0022] Preferably, in step S3, the distance for vapor deposition is 4-6 cm.

[0023] Preferably, in step S3, the method of coating the polyaniline film is to immerse the vapor-deposited conductive polyester fiber successively into the front tank reaction solution and the back tank reaction solution; the front tank reaction solution is composed of hydrogen chloride, water and polyaniline, and the back tank reaction solution is an aqueous solution of ammonium persulfate.

[0024] Preferably, in the pre-tank reaction solution, the concentration of the solute is 1.5-2.5 mol / L, the bath ratio is 8-12:1, and the molar ratio of hydrochloric acid to polyaniline is 1:1-2.

[0025] Preferably, the concentration of ammonium persulfate in the reaction solution in the post-tank is 0.8–1.4 mol / L, and the bath ratio is 5–7:1.

[0026] Preferably, in step S3, after coating with a polyaniline film, the material is dried at 70-90°C for 1-3 hours to obtain the recycled polyester chip-based electroluminescent fiber.

[0027] The technical principles of the present invention are as follows:

[0028] The vapor deposition chamber of this invention utilizes the waste heat from the melting furnace and screw extruder to provide the required temperature. This waste heat is transferred through copper tubes, which are equipped with heat insulation devices. According to Fourier's law of heat conduction, the temperature transferred to the vapor deposition chamber is approximately between 265°C and 300°C. Conductive polyester fibers enter the vapor deposition chamber after passing through a cooling device. The high temperature inside the chamber causes the zinc sulfide powder to evaporate. The vapor condenses on the surface of the cooler conductive polyester fibers, forming a luminescent layer.

[0029] The technical solution of the present invention has the following advantages compared with the prior art:

[0030] (1) This invention cleverly combines melt spinning technology with vapor deposition and in-situ polymerization, integrating multiple steps. Compared with traditional independent operations, it reduces intermediate conversion and processing steps, saves time and resources in the preparation process, reduces costs, simplifies the preparation process, and realizes industrial continuous mass production.

[0031] (2) This invention ingeniously collects the heat energy generated during melt spinning and applies it to the vapor deposition process to achieve efficient reuse of heat energy. This design reduces energy consumption and improves energy efficiency, playing a positive role in promoting environmental protection and sustainable development.

[0032] (3) The base material of this material is made of recycled polyester chips, which helps to reduce the demand for primary petroleum resources and reduce the pressure on natural resources. At the same time, the production of recycled polyester chips helps to reduce environmental pollution caused by landfill and incineration, and reduce the negative impact on the natural environment. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the production of recycled polyester chip-based electroluminescent fibers in this invention.

[0034] Figure 2 This is a cross-sectional view of the electroluminescent fiber prepared in this invention.

[0035] Explanation of reference numerals in the attached drawings: 1-Drying tower, 2-Melting furnace, 3-Screw extruder, 4-Filter, 5-Metering pump, 6-Circular spinneret, 7-Cooling device, 8-First copper tube, 9-Second copper tube, 10-Evaporation chamber, 11-Front tank of reaction pool, 12-Rear tank of reaction pool, 13-PET-ZnS-PANI electroluminescent fiber, 14-Collection roller, 15-Conductive recycled polyester fiber, 16-ZnS luminescent layer, 17-Polyaniline conductive coating. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0037] Clean polyester flakes were obtained from post-consumer recycled bottles through wet crushing, repeated washing, and multi-stage separation. Conductive carbon black was purchased from Tianjin Yiborui Chemical Co., Ltd.; polyaniline, hydrochloric acid, and ammonium persulfate were purchased from Sinopharm Chemical Reagent Co., Ltd. Zinc sulfide powder, with a particle size of 20-30 μm, was purchased from Shanghai Keyan Optoelectronic Technology Co., Ltd.

[0038] Example 1

[0039] First, recycled bottles are collected. Using a combination of mechanical and chemical processes, various impurities are removed through wet crushing, washing and flotation, rinsing, dehydration and drying, and dry crushing, along with separation techniques such as density separation and magnetic separation. This process ultimately produces clean polyester fragments with a diameter of approximately 1 cm. These fragments are then dried using a dewatering and drying machine to reduce the moisture content to below 0.5%. The clean polyester fragments are then mixed with 10 wt% conductive carbon black and subjected to melting, extrusion, melt filtration, granulation, and online crystallization to prepare conductive recycled polyester chips. The melting temperature and time are controlled to achieve a viscosity of 0.68 dL / g for the resulting conductive recycled polyester chips.

[0040] Conductive recycled polyester chips are dried in drying tower 1 and then added to melting furnace 2. Melting furnace 2 is heated by a first copper tube 8, which has a cross-sectional area of ​​1 cm². 2 The first copper tube 8, with a length of 4m and a thermal conductivity of 400W / (m·K), has a heat-insulating outer shell at a temperature of 285℃, which melts and mixes the polyester chips and carbon black. The mixture then enters the screw extruder 3, which is heated to 300℃ by the second copper tube 9, which is 5m long. The mixture is then filtered through a filter and passed through a metering pump 5, which controls the fiber extrusion speed to 15m / min. The fiber then passes through a circular spinneret 6 with a 150μm aperture and a cooling airflow speed of 750m / min at a cooling temperature of 25℃ to obtain PET-ZnS-PANI conductive polyester fiber 13.

[0041] PET-ZnS-PANI conductive polyester fiber 13 enters the vapor deposition chamber 10. The heating copper pipes of the melting furnace 2 and the screw extruder 3 extend into the vapor deposition chamber 10. The vapor deposition chamber 10 is heated by the residual heat of the first copper pipe 8 and the second copper pipe 9 at a temperature of 275°C. The vapor deposition chamber 10 is evacuated to a pressure of about 0.1 MPa. Zinc sulfide powder is placed inside the vapor deposition chamber 10. The PET-ZnS-PANI conductive polyester fiber is positioned 4 cm above the zinc sulfide powder and is coiled around it, allowing the zinc sulfide to fully evaporate onto the surface of the conductive polyester fiber, forming a ZnS luminescent layer 16.

[0042] Finally, the fibers are immersed in a polyaniline reaction tank, which is divided into a front tank 11 and a rear tank 12. The front tank 11 contains a polyaniline / hydrochloric acid mixed solution with a molar ratio of hydrochloric acid to polyaniline of 1:1, a concentration of 1.5 mol / h, and a bath ratio of 10:1. The rear tank 12 contains an ammonium persulfate solution with a concentration of 0.8 mol / L and a bath ratio of 6:1. The fibers first adsorb the polyaniline-doped acid solution through the front tank 11, and then pass through the ammonium persulfate solution, forming a polyaniline conductive coating 17 on the fiber surface through oxidative polymerization. Finally, the fibers wound onto the collecting roller are placed in an oven at 80°C and dried for 2 hours.

[0043] Example 2

[0044] The preparation and testing methods in this embodiment are similar to those in Example 1, except that:

[0045] The carbon black concentration is 15 wt%, and the viscosity of the conductive recycled polyester chips is 0.78 dL / g.

[0046] The copper tube has a diameter of 2 cm, the melting furnace heating temperature is 275℃, and the screw extruder heating temperature is 295℃. The fiber extrusion speed is controlled by a metering pump at 14 m / min, and the cooling device has a cooling temperature of 20℃.

[0047] The heating temperature of the vapor deposition chamber is 270℃.

[0048] The concentration of the polyaniline / hydrochloric acid mixed solution is 2 mol / L, and the concentration of the ammonium persulfate solution is 1 mol / L.

[0049] Example 3

[0050] The preparation and testing methods in this embodiment are similar to those in Example 1, except that:

[0051] The carbon black concentration is 20 wt%, and the viscosity of the conductive recycled polyester chips is 0.82 dL / g.

[0052] The copper tube has a diameter of 2 cm, the melting furnace heating temperature is 290℃, and the screw extruder heating temperature is 300℃. The fiber extrusion speed is controlled by a metering pump at 16 m / min, the cooling airflow speed of the cooling device is 600 m / min, and the cooling temperature is 30℃.

[0053] The heating temperature of the vapor deposition chamber is 290℃, and the vapor deposition distance is 5cm.

[0054] The concentration of the polyaniline / hydrochloric acid mixed solution is 2 mol / L, and the concentration of the ammonium persulfate solution is 1.2 mol / L.

[0055] Example 4

[0056] The preparation and testing methods in this embodiment are similar to those in Example 1, except that:

[0057] The carbon black concentration is 20 wt%, and the viscosity of the conductive recycled polyester chips is 0.88 dL / g.

[0058] The copper tube has a diameter of 2 cm, the melting furnace heating temperature is 295℃, and the screw extruder heating temperature is 305℃. The fiber extrusion speed is controlled by a metering pump at 16 m / min, the cooling airflow speed of the cooling device is 700 m / min, and the cooling temperature is 25℃.

[0059] The heating temperature of the vapor deposition chamber is 300℃, and the vapor deposition distance is 5cm.

[0060] The concentration of the polyaniline / hydrochloric acid mixed solution is 2.5 mol / L, and the concentration of the ammonium persulfate solution is 1.2 mol / L.

[0061] Example 5

[0062] The preparation and testing methods in this embodiment are similar to those in Example 1, except that:

[0063] The carbon black concentration is 20 wt%, and the viscosity of the conductive recycled polyester chips is 0.88 dL / g.

[0064] The copper tube has a diameter of 2 cm, the melting furnace heating temperature is 295℃, and the screw extruder heating temperature is 305℃. The fiber extrusion speed is controlled by a metering pump at 18 m / min, the cooling airflow speed of the cooling device is 800 m / min, and the cooling temperature is 30℃.

[0065] The heating temperature of the vapor deposition chamber is 300℃, and the vapor deposition distance is 6cm.

[0066] The concentration of the polyaniline / hydrochloric acid mixed solution was 2.5 mol / L, and the concentration of the ammonium persulfate solution was 1.4 mol / L.

[0067] Comparative Example 1

[0068] The preparation and testing methods of this comparative example are similar to those of Example 4, except that:

[0069] The carbon black concentration is 5 wt%.

[0070] The concentration of the polyaniline / hydrochloric acid mixed solution is 0.5 mol / L, and the concentration of the ammonium persulfate solution is 0.6 mol / L.

[0071] The carbon black concentration is low, resulting in excessively high resistivity, reaching 1865.2 × 10⁻⁶. 3 Ω / cm.

[0072] Comparative Example 2

[0073] The preparation and testing methods of this comparative example are similar to those of Example 4, except that:

[0074] The carbon black concentration is 25 wt%.

[0075] If the carbon black concentration is too high, the intrinsic viscosity of the CB / PET conductive masterbatch will be high, resulting in poor melt flow properties, lack of spinnability, and inability to be used for composite spinning.

[0076] Comparative Example 3

[0077] The preparation and testing methods of this comparative example are similar to those of Example 4, except that:

[0078] The concentration of the polyaniline / hydrochloric acid mixed solution is 3.5 mol / L, and the concentration of the ammonium persulfate solution is 1.6 mol / L.

[0079] A higher concentration of ammonium persulfate results in a greater thickness of polyaniline on the fiber surface, leading to a larger coverage area and larger agglomerated particle size. This, in turn, reduces electrical conductivity, resulting in a resistivity of 16.92 × 10⁻⁶. 3 Ω / cm.

[0080] Performance Evaluation and Testing

[0081] According to GB / T 14344-2008 "Test Method for Tensile Properties of Chemical Fiber Filaments", the tensile properties of the examples were tested using a universal testing machine (model: Instron3365, purchased from Instron Corporation, USA). 60cm specimens were prepared according to GB / T 6502, and the tensile rate was 50mm / min.

[0082] The brightness of the electroluminescent fiber was tested using an absolute luminance meter (model: BM7A, purchased from Topcon) with 110V, 11kHz AC power.

[0083] The samples used to test the resistance of polyester / carbon black fibers were directly produced from conductive polyester chips through melt spinning, without undergoing vapor deposition or in-situ polymerization.

[0084] The sample used to test the resistance of polyester / polyaniline fiber was prepared from polyester fiber with the same process specifications as in this embodiment. The polyester fiber was then subjected to in-situ polymerization to form a polyaniline film on its surface. No carbon black was added and no vapor deposition process was performed.

[0085] The resistance of conductive fibers was tested using a high insulation resistance meter (model: ZC-90G, purchased from Shanghai Taiou Electric Co., Ltd.). The test conditions were: temperature 20℃, humidity 35%, sample equilibration for 24 hours, 10 locations for each sample, and average value.

[0086] The obtained data is shown in Table 1.

[0087] Table 1 Performance Tests of Each Embodiment

[0088]

[0089]

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing recycled polyester chip-based electroluminescent fibers, characterized in that, Includes the following steps: S1: Carbon black and recycled polyester chips are mixed, melted, extruded, and granulated to obtain conductive recycled polyester chips; the mass fraction of carbon black in the conductive recycled polyester chips is 10-20 wt%. S2: The conductive recycled polyester chips are melt-spun to obtain conductive polyester fibers; S3: In the vapor deposition chamber, a zinc sulfide film is vapor-deposited onto the surface of the conductive polyester fiber, followed by coating with a polyaniline film to obtain the recycled polyester chip-based electroluminescent fiber; in step S3, the method of coating with the polyaniline film is to immerse the vapor-deposited conductive polyester fiber successively into the front tank reaction solution and the back tank reaction solution; the front tank reaction solution is composed of hydrogen chloride, water and polyaniline, and the back tank reaction solution is an aqueous solution of ammonium persulfate; in the front tank reaction solution, the concentration of the solute is 1.5-2.5 mol / L, the bath ratio is 8-12:1, and the molar ratio of hydrochloric acid to polyaniline is 1:1-2; in the back tank reaction solution, the concentration of ammonium persulfate is 0.8-1.4 mol / L, and the bath ratio is 5-7:

1.

2. The preparation method according to claim 1, characterized in that, The melting temperature is 275-295℃, and the granulation temperature is 285-305℃.

3. The preparation method according to claim 1, characterized in that, The melting process is carried out using a melting furnace, and the granulation process is carried out using a screw extruder. The melting furnace and the screw extruder are respectively connected to copper pipes; both the melting furnace and the screw extruder are heated through copper pipes.

4. The preparation method according to claim 3, characterized in that, The copper tube is also connected to the vapor deposition chamber, and the vapor deposition is carried out by heating the copper tube to 265-300℃.

5. The preparation method according to claim 3, characterized in that, The cross-sectional area of ​​the copper tube is 1-2 cm². 2 It has a length of 4-5 m and a thermal conductivity of 380-420 W / (m·K).

6. The preparation method according to claim 1, characterized in that, In step S3, after coating with a polyaniline film, the material is dried at 70-90°C for 1-3 hours to obtain the recycled polyester chip-based electroluminescent fiber.

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