Light-absorbing and heating composite fiber and preparation method thereof

Abstract

The invention relates to the technical field of composite fibers, in particular to a light-absorbing and heat-generating composite fiber and a preparation method thereof.The preparation process comprises the following steps that 1, core-shell structure light-absorbing and heat-generating particles are prepared; (2) carrying out surface modification on ferroferric oxide coated silicon dioxide particles; (3) in-situ polymerization; and (4) melt spinning. According to the scheme, nano ferroferric oxide is selected as a core light absorption material, and due to a unique Fe < 2 + > / Fe < 3 + > mixed valence electronic structure, while wide-spectrum light absorption is realized, oxidative photo-generated holes are hardly generated, so that the photocatalytic degradation risk similar to titanium dioxide is avoided from the source, and the long-term stability of a polymer matrix is guaranteed; in combination with in-situ polymerization, axial gradient magnetic field spinning processes and the like, the washing resistance, aging resistance and strength of the light-absorbing and heating composite fiber are synchronously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fibers, and in particular to a light-absorbing and heat-generating composite fiber and a preparation method thereof. Background Art

[0002] With the continuous development of functional fiber technology, light-absorbing, heat-generating fibers have gradually become a research hotspot in the textile materials field due to their excellent thermal insulation properties and broad application prospects. However, existing light-absorbing, heat-generating fibers still have some shortcomings in terms of preparation process, functional stability, and overall performance optimization, which affect their long-term performance and market competitiveness.

[0003] CN116988185B discloses a method for preparing light-absorbing and heat-generating polylactic acid fibers, with a publication date of December 5, 2023. This patent prepares fibers with excellent comprehensive properties such as light-absorbing and heat-generating, dyeing, and strength by mixing polylactic acid with low-molecular-weight water-soluble polyester, high-molecular-weight water-soluble polyester, and light-absorbing and heat-generating materials and then melt-spinning them. However, in this technical solution, the light-absorbing and heat-generating materials are directly mixed into the polymer matrix, which may lead to catalytic degradation of the fiber matrix by nano-inorganic particles, causing the fibers to exhibit functional attenuation and weakened heating effects during multiple washing, drying, or use. In addition, this method has high requirements for the control of raw material ratio and zero-cut viscosity, which may increase process complexity and production costs. CN113215679B discloses a method for preparing light-absorbing and heat-generating polyamide-based elastic fibers, with a publication date of June 17, 2022. This patent prepares elastic fibers with excellent light-absorbing and heat-generating properties by melt-spinning the polycondensation reaction of caprolactam, aliphatic dibasic acid, aliphatic diol, and polyethylene glycol mixed with light-absorbing and heat-generating powder. However, in this technical solution, the way the light-absorbing and heat-generating powder is introduced may lead to its uneven distribution in the fiber, thereby affecting the consistency of the heat-generating properties. In addition, although the addition of polyethylene glycol improves the flexibility of the fiber, it may reduce the heat resistance and mechanical strength of the fiber, limiting its application in high-temperature environments.

[0004] The above problems indicate that the existing light-absorbing and heating fibers still have certain deficiencies in preparation process, functional stability, durability and comprehensive performance optimization. Summary of the Invention

[0005] To this end, the present invention provides a light-absorbing and heat-generating composite fiber and a preparation method thereof to solve the above-mentioned problems in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing the above-mentioned light-absorbing and heat-generating composite fiber comprises the following steps, in parts by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: Disperse 0.5-3 parts of ferroferric oxide nanoparticles in ethanol, add 0.1-0.5 parts of aqueous ammonia, where the mass percentage of ammonia in the aqueous ammonia is 25wt%-28wt%; then dropwise add 1-5 parts of ethyl orthosilicate to react and form a silica coating, which is then washed and dried to obtain ferroferric oxide@silica particles; (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.1-0.3 parts of silane coupling agent, and reflux for 6-12 hours; then add 0.2-0.6 parts of hydroxyethyl acrylate and 0.01-0.03 parts of azobisisobutyronitrile, and react at 70-80°C for 4-8 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: Mix 100 parts of dimethyl terephthalate, 60-80 parts of ethylene glycol, and 0.01-0.05 parts of zinc acetate; then add 0.5-3 parts of modified ferrosoferric oxide@silica particles and carry out transesterification at 180-200°C; then heat to 260-280°C and perform vacuum polycondensation to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 270-290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber. An axial magnetic field of 0.2-0.4T is applied during the spinning process.

[0007] This approach achieves enhanced weatherability through dual protection and chemical bonding: the silica shell physically isolates the catalytically active surface of the FeO nanoparticles, blocking their pathway for initiating polymer photodegradation / hydrolysis. Simultaneously, the grafted hydroxyethyl acrylate forms covalent ester bonds with the polyester matrix during polycondensation, anchoring the particles to the molecular chain network and inhibiting interfacial debonding. This synergistic "shell isolation + chemical bonding" mechanism ensures stable dispersion and functional integrity of the particles despite stresses such as washing and light exposure. Ammonia serves as a dual-functional modulator of the coating reaction in this method: the released hydroxide ions efficiently catalyze the hydrolysis of ethyl orthosilicate to form active silanols (Si-OH). Meanwhile, the weakly alkaline environment (pH ≈ 9-11) precisely inhibits excessive polycondensation of the silanols, ensuring directional deposition of silica on the FeO surface at a controlled rate. Furthermore, ammonia molecules temporarily bind to Fe-OH groups on the particle surface through hydrogen bonds, directing the polycondensation of the silanols preferentially at the particle interface, ultimately forming a dense and uniform silica isolation layer.

[0008] The fundamental reason for choosing nano-ferroferric oxide is its unique electronic structure: Fe 2+ / Fe 3+The mixed valence state forms a continuous energy level in the bandgap, which enables it to have efficient and wide-spectrum light absorption capabilities while almost no oxidizing photogenerated holes are produced (different from wide-bandgap semiconductors such as titanium dioxide), avoiding the risk of photocatalytic degradation of polymers from the source; its moderate magnetic responsiveness not only meets the magnetic field orientation requirements, but also avoids the uncontrollable agglomeration caused by strong magnetism, forming a "light absorption-magnetic control-protection" functional balance with the silica coating.

[0009] The axial magnetic field refers to the magnetic field parallel to the direction of melt movement. The core value of spinning in a magnetic field lies in constraining the orientation of ferroferric oxide nanoparticles through the axial magnetic field, so that they are arranged in an orderly manner along the fiber axis, constructing a continuous light-heat conversion path, thereby improving energy transfer efficiency and extending functional durability; at the same time, the weak magnetism of the nanoparticles makes their magnetic attraction far lower than the thermal motion energy of the melt molecules. The particles spontaneously disperse under the dominance of Brownian motion, and the physical spacing formed by the silica coating blocks the magnetic dipole interaction. The fluid shear force generated by the high shear flow field of the melt has a higher disassembly intensity for potential agglomerates than the magnetic field force. The three work together to ensure dispersion stability.

[0010] The mass ratio of ethyl orthosilicate to ferrosilicate nanoparticles controls the thickness of the silica shell, which is 5-10 nm. If it is too thin, the isolation is insufficient, and if it is too thick, light absorption is hindered.

[0011] Preferably, the ferrosoferric oxide@silicon dioxide particles are core-shell particles with a silicon dioxide shell thickness of 5-10 nm; Preferably, the silane coupling agent in step (2) is γ-methacryloxypropyltrimethoxysilane.

[0012] The amount of γ-methacryloxypropyltrimethoxysilane used ensures the double bond grafting density, avoids insufficient reaction sites or surface overload agglomeration, and ensures complete reaction of double bonds, eliminating matrix degradation caused by residual initiator.

[0013] Preferably, in step (4), the deviation angle θ between the direction of the axial magnetic field and the melt extrusion direction is ≤5°.

[0014] Preferably, in step (4), the axial magnetic field of 0.2-0.4 T applied during the spinning process is divided into two sections, one section being the magnetic field B1 before the spinning and the other section being the magnetic field B2 after the spinning. The directions of the magnetic fields B1 and B2 are the same.

[0015] Preferably, in step (4), the magnetic field strength of the magnetic field B1 is 0.3-0.4 T, and is adjusted in real time according to the melt temperature: When the melt temperature is 270-280℃, B1 is 0.3-0.35T; When the melt temperature is greater than 280°C, B1 is 0.35-0.4T.

[0016] Preferably, the ratio of the magnetic field strength of the magnetic field B2 to that of B1 is 0.8-1.0:1.

[0017] Before spinning, the melt is transported to the inlet of the spinneret (0-5 mm away from the spinneret hole), and after spinning, the melt leaves the outlet of the spinneret hole.

[0018] The above scheme produces a light-absorbing and heat-generating composite fiber, which has a polyester fiber matrix loaded with modified ferroferric oxide@silica particles; the modified ferroferric oxide@silica particles are a core-shell structure, with silica as the shell layer.

[0019] This solution also discloses the light-absorbing and heat-generating composite fiber obtained by the above solution.

[0020] The present invention has the following advantages: Nano-ferroferric oxide is selected as the core light-absorbing material, and its unique Fe 2+ / Fe 3+ The mixed valence electronic structure achieves wide-spectrum light absorption while generating almost no oxidative photogenerated holes, thus avoiding the risk of photocatalytic degradation similar to titanium dioxide from the source and ensuring the long-term stability of the polymer matrix.

[0021] In-situ polymerization is combined with axial gradient magnetic field spinning technology to graft active monomers on the surface of the particles and form chemical bonds with polyester, avoiding the weakening of heat resistance by adding external toughening agents; dynamic control of the magnetic field enables the particles to be precisely oriented along the fiber axis, breaking through the uneven dispersion defects caused by traditional blending, and simultaneously improving water resistance, aging resistance and strength. DETAILED DESCRIPTION

[0022] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention. Example 1

[0023] A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.3 parts of aqueous ammonia was added, with the mass percentage of ammonia in the aqueous ammonia being 25 wt%. Subsequently, 3 parts of ethyl orthosilicate was added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.37T; After ejection: magnetic field strength B2 is 0.35T. Example 2

[0024] A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 3 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.5 parts of ammonia water was added, where the mass percentage of ammonia in the ammonia water was 25 wt%. 5 parts of ethyl orthosilicate was then added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were then washed and dried to obtain core-shell particles with a silica shell thickness of 10 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.3 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 12 hours; then add 0.6 parts of hydroxyethyl acrylate and 0.03 parts of azobisisobutyronitrile, and react at 80°C for 8 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 80 parts of ethylene glycol, and 0.05 parts of zinc acetate were mixed; then 3 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 200°C; the temperature was raised to 280°C and vacuum polycondensed to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4 T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field intensity at the inlet section is 0.4 T; After ejection: magnetic field strength B2 is 0.4T. Example 3

[0025] A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 0.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.2 parts of ammonia water was added, where the mass percentage of ammonia in the ammonia water was 25 wt%. 1 part of ethyl orthosilicate was then added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were then washed and dried to obtain core-shell particles with a silica shell thickness of 6 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.1 part of γ-methacryloxypropyltrimethoxysilane, and reflux for 6 hours; then add 0.2 parts of hydroxyethyl acrylate and 0.01 parts of azobisisobutyronitrile, and react at 75°C for 4 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 65 parts of ethylene glycol, and 0.02 parts of zinc acetate were mixed; 0.5 parts of modified ferrosoferric oxide@silica particles were then added and transesterification was carried out at 185°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 280°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.32T; After ejection: magnetic field strength B2 is 0.28T. Example 4

[0026] 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.3 parts of aqueous ammonia was added, with the mass percentage of ammonia in the aqueous ammonia being 25 wt%. Subsequently, 3 parts of ethyl orthosilicate was added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 275°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.3T; After ejection: magnetic field strength B2 is 0.28T.

[0027] Comparative Example 1 The difference from Example 1 is that nano-titanium dioxide is used as the light-absorbing and heat-generating nanoparticles: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of nano-titanium dioxide were dispersed in ethanol, and 0.3 parts of ammonia water was added, wherein the mass percentage of ammonia in the ammonia water was 25 wt%. Subsequently, 3 parts of ethyl orthosilicate were added dropwise to react to form a silica coating layer, forming titanium dioxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) Surface modification of titanium dioxide and silicon dioxide particles: 1 part of titanium dioxide @ silicon dioxide particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane was added, and the mixture was refluxed for 8 hours. Subsequently, 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile were added, and the mixture was reacted at 75°C for 6 hours to obtain modified titanium dioxide @ silicon dioxide particles. (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; 1.5 parts of modified titanium dioxide and silicon dioxide particles were then added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensed to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.37T; After ejection: magnetic field strength B2 is 0.35T.

[0028] Comparative Example 2 The difference from Example 1 is that no core-shell structure was prepared: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Surface modification of ferroferric oxide nanoparticles: Disperse 1 part of ferrosoferric oxide nanoparticles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferrosoferric oxide nanoparticles; (2) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; 1.5 parts of modified ferrosoferric oxide nanoparticles were then added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was performed to obtain a polyester melt; (3) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.37T; After ejection: magnetic field strength B2 is 0.35T.

[0029] Comparative Example 3 The difference from Example 1 is that no ammonia is used: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and then 3 parts of ethyl orthosilicate were added dropwise to react to form a silica coating layer, forming ferroferric oxide@silica particles; the particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm; (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.37T; After ejection: magnetic field strength B2 is 0.35T.

[0030] Comparative Example 4 The difference from Example 1 is that the ferroferric oxide@silicon dioxide particles are not surface modified: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.3 parts of aqueous ammonia was added, with the mass percentage of ammonia in the aqueous ammonia being 25 wt%. Subsequently, 3 parts of ethyl orthosilicate was added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (3) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.2-0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the baseline value B1 of the axial magnetic field intensity before ejection is 0.37T; After ejection: magnetic field strength B2 is 0.35T.

[0031] Comparative Example 5 The difference from Example 1 is that spinning is not carried out in a magnetic field: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.3 parts of aqueous ammonia was added, with the mass percentage of ammonia in the aqueous ammonia being 25 wt%. Subsequently, 3 parts of ethyl orthosilicate was added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber.

[0032] Comparative Example 6 The difference from Example 1 is that the spinning magnetic field is constant at 0.4 T: A method for preparing a light-absorbing and heat-generating composite fiber comprises the following steps, calculated by weight: (1) Preparation of core-shell structured light-absorbing and heat-generating particles: 1.5 parts of ferroferric oxide nanoparticles were dispersed in ethanol, and 0.3 parts of aqueous ammonia was added, with the mass percentage of ammonia in the aqueous ammonia being 25 wt%. Subsequently, 3 parts of ethyl orthosilicate was added dropwise to react and form a silica coating, forming ferroferric oxide@silica particles. The particles were washed and dried to obtain core-shell particles with a silica shell thickness of 8 nm. (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.2 parts of γ-methacryloxypropyltrimethoxysilane, and reflux for 8 hours; then add 0.4 parts of hydroxyethyl acrylate and 0.02 parts of azobisisobutyronitrile, and react at 75°C for 6 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of modified ferrosoferric oxide@silica particles were added and transesterification was carried out at 190°C; the temperature was raised to 270°C and vacuum polycondensation was carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.4 T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°, and the axial magnetic field intensity is 0.4 T before and after ejection.

[0033] Performance testing: Light absorption and heating performance test: The fiber surface temperature rise was measured according to GB / T18319-2019 standard. The temperature rise value ΔT = (temperature after 10 minutes of illumination) - (initial temperature); Washing test: refer to AATCC135-2018, 50 cycles (40°C, 0.5% soap solution); UV aging: Refer to ISO4892-3, UVB light source (0.76W / m²), irradiation for 500h, performance retention rate = (after aging ΔT / initial ΔT) × 100%; Mechanical properties: Breaking strength refers to GB / T14344-2008 (tensile rate 20mm / min).

[0034] The test results are shown in Table 1.

[0035] Table 1

[0036] By comparing Examples 1-4 and Comparative Examples 1-6, it can be seen that although the initial heating efficiency of Examples 1-4 is not as good as that of Comparative Example 1, it can be maintained longer and has better weather resistance and water washability.

[0037] Comparative Example 1 uses TiO2 instead of Fe3O4. The core advantage of using nano-ferroferric oxide in Example 1 lies in its mixed valence electronic structure. 2+ / Fe 3+ The continuous energy levels formed in the bandgap enable it to have a wide-spectrum light absorption capability while almost no highly oxidizing photogenerated holes are generated. This fundamentally avoids the risk of wide-bandgap semiconductors such as titanium dioxide inducing polymer chain breakage under ultraviolet light, and ensures long-term photostability.

[0038] Comparative Example 2, unlike Example 1, lacks a SiO2 shell. Example 1 achieves physical isolation through a silica shell. A dense SiO2 layer, 5-10 nm thick, completely encapsulates the ferrosoferric oxide particles, blocking the Fenton reaction catalytic pathway initiated by Fe ion dissolution. This effectively inhibits the hydrolytic degradation of ethylene glycol end groups during the water washing process, maintaining the integrity of the polymer matrix.

[0039] Comparative Example 3 Compared with Example 1, the ammonia-free treatment of ammonia plays a dual-functional regulatory role in Example 1: the OH released - Ions catalyze the controlled hydrolysis of ethyl orthosilicate, while NH3 molecules guide the directional deposition of silanols on the particle surface through hydrogen bonds. This mechanism ensures the formation of a uniformly thick silicon dioxide isolation layer, avoiding pitting corrosion caused by localized protection failure.

[0040] Comparative Example 4: Compared to Example 1, the modification of Example 1 resulted in the formation of polymer chains containing active hydroxyl groups on the particle surface. During the polycondensation process, these hydroxyl groups formed covalent ester bonds with the polyester carboxyl groups, anchoring the particles to the molecular chain network, significantly enhancing interfacial bonding and suppressing interfacial debonding under washing stress.

[0041] Comparative Example 5 is a spinning without magnetic field compared to Example 1. The axial gradient magnetic field in Example 1 established a magnetorheological cooperative orientation mechanism, where the magnetic field force induced the weak magnetic particles to align along the melt flow direction, resulting in a more regular molecular arrangement after the fiber cooled.

[0042] Compared to Example 1, Comparative Example 6 uses a constant magnetic field during the spinning process. The gradient magnetic field design of Example 1 overcomes the rheological adaptation drawbacks of a constant magnetic field. The lower field strength at the inlet prevents excessive shearing of high-viscosity melts, the increased field strength in the middle section strengthens particle orientation to counteract molecular chain relaxation, and the reduced field strength at the outlet section prevents stress concentration in the solidification zone, achieving a balance between orientation and processing stability. Although the performance of Comparative Example 6 is inferior to that of Examples 1-4, it still has better durability and weather resistance than the other comparative examples.

Claims

1. A method for preparing a light-absorbing and heat-generating composite fiber, characterized in that: The following steps are involved: By weight, (1) Preparation of core-shell structured light-absorbing and heat-generating particles: Disperse 0.5-3 parts of ferroferric oxide nanoparticles in ethanol, add 0.1-0.5 parts of ammonia water; then add 1-5 parts of ethyl orthosilicate dropwise to react to form a silicon dioxide coating, wash and dry to obtain ferroferric oxide@silicon dioxide particles; (2) Surface modification of ferroferric oxide@silica particles: Disperse 1 part of ferroferric oxide@silica particles in toluene, add 0.1-0.3 parts of silane coupling agent, and reflux for 6-12 hours; then add 0.2-0.6 parts of hydroxyethyl acrylate and 0.01-0.03 parts of azobisisobutyronitrile, and react at 70-80°C for 4-8 hours to obtain modified ferroferric oxide@silica particles; (3) In situ polymerization: Mix 100 parts of dimethyl terephthalate, 60-80 parts of ethylene glycol, and 0.01-0.05 parts of zinc acetate; then add 0.5-3 parts of modified ferrosoferric oxide@silica particles and carry out transesterification at 180-200°C; then heat to 260-280°C and perform vacuum polycondensation to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 270-290°C and extruded through a spinneret, pulled, and wound to produce a light-absorbing and heat-generating composite fiber. An axial magnetic field of 0.2-0.4T is applied during the spinning process.

2. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 1, wherein: The silane coupling agent in step (2) is γ-methacryloxypropyltrimethoxysilane.

3. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 1, wherein: The mass percentage of ammonia in the ammonia water in step (1) is 25wt%-28wt%.

4. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 1, wherein: In step (4), the deviation angle θ between the direction of the axial magnetic field and the melt extrusion direction is ≤5°.

5. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 1, wherein: In step (4), the axial magnetic field of 0.2-0.4 T applied during the spinning process is divided into two sections, one section being the magnetic field B1 before the spinning is ejected and the other section being the magnetic field B2 after the spinning is ejected.

6. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 1, wherein: The magnetic field strength of magnetic field B1 is 0.3-0.4T and is adjusted in real time according to the melt temperature: When the melt temperature is 270-280℃, B1 is 0.3-0.35T; When the melt temperature is greater than 280°C, B1 is 0.35-0.4T.

7. The method for preparing the light-absorbing and heat-generating composite fiber according to claim 6, wherein: The ratio of the magnetic field strength of the magnetic field B2 to that of B1 is 0.8-1.0:

1.

8. A light-absorbing and heat-generating composite fiber prepared by the method for preparing a light-absorbing and heat-generating composite fiber as described in any one of claims 1 to 7.

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