Carbon nanotube modified thermal conductive composite fiber and manufacturing method thereof

Abstract

The invention relates to the technical field of composite fibers, and particularly discloses a carbon nanotube modified thermal conductive composite fiber and a manufacturing method thereof. Comprising the following operation steps: step 1, adding carboxylated single-walled carbon nanotubes into toluene, performing ultrasonic dispersion, adding p-toluenesulfonic acid and a biphenyl polymer, heating to 60-75 DEG C under the protection of nitrogen, reacting for 1-2 hours, continuously heating to 120-130 DEG C, reacting for 6-8 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; 2, (1) compounding the biphenyl polymer modified carbon nanotube with aminated graphene to obtain a composite material; (2) uniformly mixing the composite material, polytrimethylene terephthalate and a compatibilizer, and performing melt extrusion to obtain master batches; step 3, (1) melting the master batch, and performing centrifugal spinning treatment to obtain a nascent composite fiber; and (2) sequentially carrying out hot stretching and heat setting on the nascent composite fiber to obtain the heat-conducting composite fiber.

Description

Technical Field

[0001] The invention relates to the technical field of composite fibers, in particular to a carbon nanotube-modified thermally conductive composite fiber and a method for manufacturing the same. Background Art

[0002] With the advancement and development of science and technology, many electronic devices have been miniaturized and automated, which has led to problems such as heat dissipation and safety of these electronic devices. Electronic devices will generate a lot of heat during operation, which may damage the efficiency of the system. Therefore, people's requirements for the thermal conductivity and heat resistance of materials are also increasing.

[0003] The current thermal conductive material is to modify the thermal conductive filler and then fill it into the polymer to improve the thermal conductivity of the polymer, but the existing thermal conductive materials have not kept up with the development of the electronics industry. Polymer-based fibers have the characteristics of easy production, excellent mechanical properties, and light weight, which not only improves the performance of the material, but also promotes the development and innovation of related industries. However, the intrinsic thermal conductivity of some polymer fibers is low, which limits their development in the field of electronics. In the prior art, inorganic materials such as carbon nanotubes are usually used to improve the thermal conductivity of fibers. However, the introduction of inorganic fillers has compatibility and dispersibility problems, resulting in the failure to maximize the utilization of thermal performance and reducing the mechanical properties of the fibers.

[0004] In summary, it is of great significance to solve the above problems and prepare a carbon nanotube-modified thermally conductive composite fiber. Summary of the invention

[0005] The object of the present invention is to provide a carbon nanotube-modified thermally conductive composite fiber and a method for manufacturing the same, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for manufacturing a carbon nanotube-modified thermally conductive composite fiber comprises the following steps: Step 1: adding carboxylated single-walled carbon nanotubes to toluene, ultrasonically dispersing, adding p-toluenesulfonic acid and biphenyl polymer, heating to 60°C-75°C under nitrogen protection for 1-2 hours, and then heating to 120-130°C for 6-8 hours, purifying, and obtaining biphenyl polymer modified carbon nanotubes; Step 2: (1) Compounding biphenyl polymer-modified carbon nanotubes with amino-modified graphene to obtain a composite material; (2) uniformly mixing the composite material, poly(trimethylene terephthalate) and a compatibilizer, and melt-extruding to obtain a masterbatch; Step 3: (1) subjecting the masterbatch to melt centrifugal spinning to obtain nascent composite fibers; (2) subjecting the nascent composite fibers to thermal stretching and thermal shaping in sequence to obtain thermally conductive composite fibers.

[0007] The more optimized preparation method of the biphenyl polymer is as follows: (1) adding amino-terminated polyethylene glycol to N,N-dimethylacetamide, mixing evenly, obtaining solution A for standby use; (2) adding 4,4''-diaminoterphenyl to N,N-dimethylacetamide, mixing evenly, adding 3,3',4,4'-biphenyltetracarboxylic dianhydride, reacting for 15-20 minutes, adding solution A dropwise, continuing to react for 20-30 minutes, heating to 150°C-170°C for reaction for 1-2 hours, and then heating at 180°C-185°C for 4-5 hours to obtain a biphenyl polymer.

[0008] More optimally, the raw materials of the biphenyl polymer include the following components: by mass, 2.6-2.7 parts of 4,4''-diaminoterphenyl, 2.9-3.2 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 60-70 parts of N,N-dimethylacetamide, and 0.65-0.7 parts of amino-terminated polyethylene glycol.

[0009] The specific preparation method of the composite material is more optimized as follows: (1) ultrasonically dispersing biphenyl polymer modified carbon nanotubes in N,N-dimethylacetamide to obtain solution B for standby use; (2) adding amino graphene to N,N-dimethylacetamide, ultrasonically dispersing, adding 3,3',4,4'-biphenyltetracarboxylic dianhydride, reacting for 15-20 minutes, adding solution B, continuing to react for 40-50 minutes, heating to 150°C-170°C for reaction for 2-4 hours, and then heating at 180°C-185°C for 4-6 hours to obtain a composite material.

[0010] More optimally, the raw materials of the composite material include the following components: by mass, 1-1.2 parts of amino graphene, 50-65 parts of N,N-dimethylacetamide, 3-3.5 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 0.4-0.6 parts of biphenyl polymer modified carbon nanotubes.

[0011] More optimally, the raw materials of the biphenyl polymer modified carbon nanotubes include the following components: by mass, 0.3-0.4 parts of biphenyl polymer, 1-2 parts of carboxylated single-walled carbon nanotubes, 0.04-0.06 parts of p-toluenesulfonic acid, and 30-60 parts of toluene.

[0012] More optimally, the raw materials of the masterbatch include the following components: by weight, 60-70 parts of polytrimethylene terephthalate, 8-12 parts of composite material, and 2-3 parts of compatibilizer.

[0013] More optimally, the temperature of the melt extrusion is 160°C~200°C; the conditions for the melt centrifugal spinning treatment are: assisted by a high-pressure cyclone of 80Pa~100Pa, the rotation speed of the melt centrifugal spinning is 10000rpm~20000rpm, and the temperature of the melt centrifugal spinning is 245°C~260°C; the temperature of the hot stretching is 140°C~160°C, and the multiple of the hot stretching is 2~3 times; the temperature of the heat setting is 95°C~110°C.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: Carbon nanotubes and graphene are compounded and mixed with polytrimethylene terephthalate to make composite fibers; however, carbon nanotubes and graphene have poor dispersion in polytrimethylene terephthalate, which reduces the thermal conductivity and mechanical properties of the composite fibers. In order to improve the performance of the composite fibers, the surfaces of carbon nanotubes and graphene are chemically modified to increase the dispersion of the two in the polytrimethylene terephthalate matrix, thereby improving the thermal conductivity and mechanical properties of the composite fibers.

[0015] In order to improve the thermal conductivity of the composite fiber, the present invention introduces carboxyl groups on single-walled carbon nanotubes, reacts with hydroxyl groups on biphenyl polymers to obtain biphenyl polymer-modified carbon nanotubes, and finally composites with amino graphene to form a thermal conductive network, so that a synergistic thermal conductive effect is generated between the carbon nanotubes, graphene, and biphenyl polymers, and is beneficial to further improve the interfacial heat transfer with polytrimethylene terephthalate.

[0016] In the scheme, the biphenyl polymer is prepared by amminating polyethylene glycol at one end, and then connecting the aminated polyethylene glycol at one end to 4,4''-diaminoterphenyl through the anhydride bond on 3,3',4,4'-biphenyltetracarboxylic dianhydride; wherein the terminal hydroxyl groups of polyethylene glycol can strengthen the intermolecular interaction, thereby being beneficial to improving thermal conductivity, but the interaction between the terminal hydroxyl groups weakens with increasing chain length, resulting in reduced thermal conductivity; the present invention introduces a biphenyl structure into polyethylene glycol to obtain a biphenyl polymer, which can effectively improve the rigidity of polyethylene glycol and inhibit the internal rotation of chain segments, reduce the influence of chain conformational changes on phonon scattering, and at the same time improve the heat resistance and thermal conductivity of the polymer.

[0017] In order to further improve the thermal conductivity of the composite fiber, in the scheme, the composite material, polytrimethylene terephthalate, and the compatibilizer are melt-extruded and melt-centrifugal-spun to obtain primary composite fibers; the primary composite fibers are then heat-stretched and heat-set in sequence to obtain thermally conductive composite fibers.

[0018] Among them, melt extrusion can improve the overall density and structural consistency between the components, which is beneficial to improving the thermal conductivity and mechanical properties of the composite fiber; the fibers thrown out during the melt centrifugal spinning process can be stretched and cooled in a short time by a high-pressure cyclone, which can effectively improve the production efficiency; in order to prevent the molecular chain entanglement during melt centrifugal spinning, the present invention will obtain the primary fiber by thermal stretching, which can improve the orientation and arrangement of the composite material in the matrix, not only improve the mechanical properties of the thermally conductive composite fiber, but also reduce the entanglement of the molecular chains in the composite material, reduce the phonon scattering phenomenon, and improve its phonon transfer efficiency, thereby improving the thermal conductivity of the composite fiber. DETAILED DESCRIPTION

[0019] The following is a preferred implementation of the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. For ordinary technicians in this technical field, all other embodiments obtained by ordinary technicians in this field without creative work without departing from the principle of the embodiment of the present invention are within the scope of protection of the present invention.

[0020] In the following specific embodiments, parts are by mass. In this embodiment, it should be noted that the purchase manufacturers of all raw materials involved in the present invention are not subject to any special restrictions, and exemplary examples include: the CAS number of toluenesulfonyl chloride is 26763-71-3, the CAS number of potassium iodide is 7681-11-0, the CAS number of silver chloride is 7783-90-6, and the model of single-walled carbon nanotubes is SWCNT-005, purchased from Zhejiang Yamei Nano Technology Co., Ltd.; the item number of graphene is M39032, purchased from Shanghai Mairui Biochemical Technology Co., Ltd.; the item number of polytrimethylene terephthalate is 26590-75-0, purchased from Chongqing Ruiya Biotechnology Co., Ltd.; ABS-g-MAH (compatibilizer) with a product number of 5541254 was purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd.; ethylenediamine with a CAS number of 107-15-3, 3-aminopropyltriethoxysilane with a CAS number of 919-30-2, 4,4''-diaminoterphenyl with a CAS number of 3365-85-3, 3,3',4,4'-biphenyltetracarboxylic dianhydride with a CAS number of 2420-87-3, p-toluenesulfonic acid (catalyst) with a CAS number of 104-15-4, and polyethylene glycol (PEG, molecular weight of 200~600, 6000) was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0021] The preparation method of carboxylated single-walled carbon nanotubes is as follows: adding single-walled carbon nanotubes to a mixed solution of sulfuric acid and nitric acid (the mass ratio of sulfuric acid to nitric acid is (3:1)), ultrasonically dispersing for 40 minutes, reflux reacting at 100°C for 4.5 hours, cooling to room temperature, centrifuging to remove the supernatant, washing the precipitate with deionized water until neutral, washing 4 times with ethanol, and drying at 75°C to obtain carboxylated carbon nanotubes.

[0022] The preparation method of amino graphene is as follows: 1 g of graphene is added to 400 mL of N, N-dimethylformamide, ultrasonically treated at a temperature of 35° C. and a power of 100 W for 45 minutes, 350 mL of ethylenediamine is added, ultrasonicated for 1.2 hours, 0.02 g of tetramethyluronium hexafluorophosphate is added, the temperature is raised to 65° C., condensed and refluxed for 6 hours, cooled to room temperature, diluted with ethanol, washed, filtered, and dried to obtain amino graphene.

[0023] Embodiment 1: A method for manufacturing a carbon nanotube-modified thermally conductive composite fiber, comprising the following steps: Step 1: (1) Add 1 g of polyethylene glycol (molecular weight 200) to 30 mL of dichloromethane, add 0.25 g of silver chloride, 0.125 g of p-toluenesulfonyl chloride, and 0.175 g of potassium iodide, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product; add 50 mL (25 wt%) of ammonia water and 0.36 g of ammonium chloride to the obtained intermediate product, react at 40°C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) ultrasonically disperse 0.45 parts of biphenyl polymer modified carbon nanotubes in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1 part of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution B dropwise, add completely over 20 minutes, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) melt-extrude 10 parts of the composite material, 70 parts of polytrimethylene terephthalate, and 2 parts of ABS-g-MAH compatibilizer at 255°C to obtain a masterbatch; (2) melt-centrifugal spinning the masterbatch at a rotation speed of 10,000 rpm and a temperature of 260°C under a high-pressure cyclone of 80 Pa to obtain a nascent composite fiber; (3) heat-stretching the nascent composite fiber at 150°C with a stretching ratio of 2.5, and heat-setting at 100°C to obtain a thermally conductive composite fiber.

[0024] Embodiment 2: A method for manufacturing a carbon nanotube-modified thermally conductive composite fiber, comprising the following steps: Step 1: (1) Add 3 g of polyethylene glycol (molecular weight 600) to 50 mL of dichloromethane, add 0.5 g of potassium iodide, 0.32 g of p-toluenesulfonyl chloride, and 0.7 g of silver chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 1.02 g of ammonium chloride and 60 mL (25 wt%) of ammonia water, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) ultrasonically disperse 0.45 parts of biphenyl polymer modified carbon nanotubes in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1.2 parts of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, dropwise add solution B, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) melt-extrude 15 parts of a composite material, 70 parts of polytrimethylene terephthalate, and 2 parts of an ABS-g-MAH compatibilizer at 255°C to obtain a masterbatch; (2) melt-centrifugal spinning the masterbatch at a rotation speed of 15,000 rpm and a temperature of 260°C under a high-pressure cyclone of 90 Pa, and collect the resultant to obtain a nascent composite fiber; (3) heat-stretch the nascent composite fiber at 150°C with a stretching ratio of 2.5, and heat-set at 100°C to obtain a thermally conductive composite fiber.

[0025] Embodiment 3: A method for manufacturing a carbon nanotube-modified thermally conductive composite fiber, comprising the following steps: Step 1: (1) Add 2 g of polyethylene glycol (molecular weight 400) to 30 mL of dichloromethane, add 0.21 g of potassium iodide, 0.18 g of p-toluenesulfonyl chloride, and 0.26 g of silver chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 0.45 g of ammonium chloride and 60 mL (25 wt%) of ammonia water, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) ultrasonically disperse 0.45 parts of biphenyl polymer modified carbon nanotubes in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1.2 parts of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, dropwise add solution B, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) melt-extrude 13 parts of a composite material, 70 parts of polylactic acid, and 2 parts of an acrylic compatibilizer at 255°C to obtain a masterbatch; (2) melt-centrifugal spinning the masterbatch at a rotation speed of 15,000 rpm and a temperature of 260°C under a high-pressure cyclone of 90 Pa, and collect the melt-spun masterbatch to obtain a nascent composite fiber; (3) heat-stretching the nascent composite fiber at 150°C with a stretching ratio of 2.5, and heat-setting at 100°C to obtain a thermally conductive composite fiber.

[0026] Comparative Example 1 is based on Example 2, but no biphenyl group is introduced into PEG; Step 1: (1) Add 3 g of polyethylene glycol (molecular weight 600) to 50 mL of dichloromethane, add 0.5 g of potassium iodide, 0.32 g of p-toluenesulfonyl chloride, and 0.7 g of silver chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 1.02 g of ammonium chloride and 60 mL (25 wt%) of ammonia water, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of amino-terminated polyethylene glycol, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain polyethylene glycol-grafted carbon nanotube material; Step 2: (1) ultrasonically disperse 0.45 parts of polyethylene glycol grafted carbon nanotube material in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1.2 parts of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, dropwise add solution B, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) melt-extrude 15 parts of a composite material, 70 parts of polytrimethylene terephthalate, and 2 parts of an ABS-g-MAH compatibilizer at 255°C to obtain a masterbatch; (2) melt-spin the masterbatch at a high-pressure cyclone of 90 Pa, a rotation speed of 15,000 rpm, and a temperature of 260°C, and collect the melt-spun masterbatch to obtain a nascent composite fiber; (3) heat-stretch the nascent composite fiber at 150°C with a stretching ratio of 2.5, and heat-set it at 100°C to obtain a thermally conductive composite fiber.

[0027] Comparative Example 2 is based on Example 2, but the molecular weight of PEG is increased; Step 1: (1) Add 3 g of polyethylene glycol (molecular weight 6000) to 50 mL of dichloromethane, add 0.65 g of potassium iodide, 0.32 g of p-toluenesulfonyl chloride, and 0.7 g of silver chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 60 mL (25 wt%) of ammonia water and 1.03 g of ammonium chloride, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) ultrasonically disperse 0.45 parts of biphenyl polymer modified carbon nanotubes in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1.2 parts of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, dropwise add solution B, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) melt-extrude 15 parts of a composite material, 70 parts of polytrimethylene terephthalate, and 2 parts of an ABS-g-MAH compatibilizer at 255°C to obtain a masterbatch; (2) melt-spin the masterbatch at a high-pressure cyclone of 90 Pa, a rotation speed of 15,000 rpm, and a temperature of 260°C, and collect the melt-spun masterbatch to obtain a nascent composite fiber; (3) heat-stretch the nascent composite fiber at 150°C with a stretching ratio of 2.5, and heat-set it at 100°C to obtain a thermally conductive composite fiber.

[0028] Comparative Example 3 is based on Example 2 and directly performs melt centrifugal spinning treatment; Step 1: (1) Add 3 g of polyethylene glycol (molecular weight 600) to 50 mL of dichloromethane, add 0.7 g of silver chloride, 0.5 g of potassium iodide, and 0.32 g of p-toluenesulfonyl chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 60 mL (25 wt%) of ammonia water and 1.02 g of ammonium chloride, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) ultrasonically disperse 0.45 parts of biphenyl polymer modified carbon nanotubes in 30 parts of N,N-dimethylacetamide to obtain solution B for standby use; (2) add 1.2 parts of amino graphene to 25 parts of N,N-dimethylacetamide, ultrasonically disperse, add 3 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, dropwise add solution B, heat to 170°C for reaction for 3 hours, and then heat at 180°C for 5 hours to obtain a composite material; Step 3: (1) 15 parts of the composite material, 70 parts of poly(trimethylene terephthalate), and 2 parts of ABS-g-MAH compatibilizer are melt-spun by centrifugal spinning at a speed of 15,000 rpm and a temperature of 260° C. under a high-pressure cyclone of 90 Pa to obtain a thermally conductive composite fiber.

[0029] Comparative Example 4 is based on Example 2, but graphene is not introduced; Step 1: (1) Add 3 g of polyethylene glycol (molecular weight 600) to 50 mL of dichloromethane, add 0.7 g of silver chloride, 0.5 g of potassium iodide, and 0.32 g of p-toluenesulfonyl chloride, react at room temperature for 3 hours, filter, wash, and rotary evaporate to obtain an intermediate product, add 60 mL (25 wt%) of ammonia water and 1.02 g of ammonium chloride, react at 40 ° C for 60 hours, and purify to obtain amino-terminated polyethylene glycol (NH2-PEG-OH); (2) Add 0.65 parts of amino-terminated polyethylene glycol to 30 parts of N,N-dimethylacetamide, mix evenly, and obtain solution A for standby use; (3) Add 2.6 parts of 4,4''-diaminoterphenyl to 35 parts of N,N-dimethylacetamide, mix evenly, add 2.9 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, react for 15 minutes, add solution A dropwise, heat to 165°C for reaction for 2 hours, and then heat at 180°C for 4 hours to obtain a biphenyl polymer; (4) adding 1.2 parts of carboxylated single-walled carbon nanotubes to 40 parts of toluene, ultrasonically dispersing, adding 0.04 parts of p-toluenesulfonic acid and 0.3 parts of biphenyl polymer, heating to 70°C for reaction for 1 hour under nitrogen protection, and then heating to 120°C for reaction for 6 hours, and purifying to obtain biphenyl polymer modified carbon nanotubes; Step 2: (1) melt-extrude 15 parts of a composite material, 70 parts of polytrimethylene terephthalate, and 2 parts of an ABS-g-MAH compatibilizer at 255°C to obtain a masterbatch; (2) melt-centrifugal spinning the masterbatch at a rotation speed of 15,000 rpm and a temperature of 260°C under a high-pressure cyclone of 90 Pa, and collect the resulting nascent composite fibers; (3) heat-stretching the nascent composite fibers at 150°C with a stretching ratio of 2.5, and heat-setting at 100°C to obtain thermally conductive composite fibers.

[0030] Test experiment 1: (1) The mechanical properties of Examples 1 to 3 and Comparative Examples 1 to 4 were tested according to GB / T14337-2008, as shown in Table 1; (2) The thermal conductivity indexes of Examples 1 to 3 and Comparative Examples 1 to 4 were tested according to ASTM E1461, as shown in Table 1.

[0031] Table 1

[0032] Conclusion: Comparative Example 1 is based on Example 2, and no biphenyl group is introduced on PEG, which reduces the thermal conductivity and strength of the thermally conductive composite fiber; because the biphenyl group can inhibit the internal rotation of the polyethylene glycol chain segment, and at the same time provides a certain rigidity, reducing the effect of chain conformation changes on phonon scattering. Comparative Example 2 is based on Example 2, and the molecular weight of PEG is increased, so that the thermal conductivity and strength of the thermally conductive composite fiber are reduced; although the terminal hydroxyl groups of polyethylene glycol can strengthen the intermolecular effect, the effect between the terminal hydroxyl groups is weakened as the chain length increases, thereby affecting the thermal conductivity of the thermally conductive composite fiber. Comparative Example 3 is based on Example 2, and melt centrifugal treatment is directly performed, so that the thermal conductivity and strength of the thermally conductive composite fiber are reduced; because melt extrusion can improve the overall density and structural consistency of the thermally conductive composite fiber, which is beneficial to improve the mechanical properties and thermal conductivity of the thermally conductive composite fiber; and hot stretching makes it easier to orient the molecules and molecular chains along the stretching direction during melt centrifugal spinning, which can not only make full use of the biphenyl polymer main chain for heat transport, but also improve the thermal conductivity of the thermally conductive composite fiber. Comparative Example 4 is based on Example 2, but graphene is not introduced, resulting in decreased thermal conductivity and strength.

[0033] Finally, it should be noted that the above is only a preferred embodiment of the present invention, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the spirit and principle of the present invention and within the technical scope disclosed in this application should be included in the protection scope of this application; in the absence of conflict, the embodiments of this application and the features in the embodiments can be combined with each other. Therefore, the protection scope of this application shall be based on the protection scope of the claims.

Claims

1. A method for producing a thermally conductive composite fiber modified with carbon nanotubes, characterized in that: The steps include: Step 1: adding carboxylated single-walled carbon nanotubes to toluene, ultrasonically dispersing, adding p-toluenesulfonic acid and biphenyl polymer, heating to 60-75°C for reaction for 1-2 hours under nitrogen protection, and then heating to 120-130°C for reaction for 6-8 hours, purifying, and obtaining biphenyl polymer modified carbon nanotubes; Step 2: (1) Compounding biphenyl polymer-modified carbon nanotubes with amino-modified graphene to obtain a composite material; (2) uniformly mixing the composite material, poly(trimethylene terephthalate) and a compatibilizer, and melt-extruding to obtain a masterbatch; Step 3: (1) subjecting the masterbatch to melt centrifugal spinning to obtain nascent composite fibers; (2) subjecting the nascent composite fibers to thermal stretching and thermal shaping in sequence to obtain thermally conductive composite fibers.

2. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 1, characterized in that: The preparation method of the biphenyl polymer is as follows: (1) adding amino-terminated polyethylene glycol to N,N-dimethylacetamide, mixing uniformly, obtaining solution A for standby use; (2) adding 4,4''-diaminoterphenyl to N,N-dimethylacetamide, mixing uniformly, adding 3,3',4,4'-biphenyltetracarboxylic dianhydride, reacting for 15-20 minutes, adding solution A dropwise, continuing to react for 20-30 minutes, heating to 150-170°C for reaction for 1-2 hours, and then heating at 180-185°C for 4-5 hours to obtain the biphenyl polymer.

3. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 2, characterized in that: The raw materials of the biphenyl polymer include the following components: by mass, 2.6-2.7 parts of 4,4''-diaminoterphenyl, 2.9-3.2 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 60-70 parts of N,N-dimethylacetamide, and 0.65-0.7 parts of amino-terminated polyethylene glycol.

4. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 1, characterized in that: The specific preparation method of the composite material is as follows: (1) ultrasonically dispersing biphenyl polymer modified carbon nanotubes in N,N-dimethylacetamide to obtain solution B for standby use; (2) adding amino graphene to N,N-dimethylacetamide, ultrasonically dispersing, adding 3,3',4,4'-biphenyltetracarboxylic dianhydride, reacting for 15-20 minutes, adding solution B, continuing to react for 40-50 minutes, heating to 150°C-170°C for reaction for 2-4 hours, and then heating at 180°C-185°C for 4-6 hours to obtain the composite material.

5. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 4, characterized in that: The raw materials of the composite material include the following components: by weight, 1-1.2 parts of amino graphene, 50-65 parts of N,N-dimethylacetamide, 3-3.5 parts of 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 0.4-0.6 parts of biphenyl polymer modified carbon nanotubes.

6. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 1, characterized in that: The raw materials of the biphenyl polymer modified carbon nanotubes include the following components: by mass, 0.3-0.4 parts of biphenyl polymer, 1-2 parts of carboxylated single-walled carbon nanotubes, 0.04-0.06 parts of p-toluenesulfonic acid, and 30-60 parts of toluene.

7. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 1, characterized in that: The raw materials of the masterbatch include the following components: by weight, 60-70 parts of polytrimethylene terephthalate, 8-15 parts of composite material, and 2-3 parts of compatibilizer.

8. The method for producing a carbon nanotube-modified thermally conductive composite fiber according to claim 1, characterized in that: The temperature of the melt extrusion is 250°C~260°C; the conditions of the melt centrifugal spinning treatment are: assisted by a high-pressure cyclone of 80Pa~100Pa, the rotation speed of the melt centrifugal spinning is 10000rpm~20000rpm, and the temperature of the melt centrifugal spinning is 245°C~270°C; the temperature of the hot stretching is 140°C~160°C, and the multiple of the hot stretching is 2~3 times; the temperature of the heat setting is 95°C~110°C. 9 . A thermally conductive composite fiber prepared according to the method for preparing a thermally conductive composite fiber modified by carbon nanotubes according to any one of claims 1 to 8 .

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