Light-absorbing heat-generating composite fiber and method for manufacturing the same

Abstract

The present application relates to the technical field of composite fibers, in particular to a light-absorbing and heat-generating composite fiber and a preparation method thereof, and the preparation process comprises the following steps: (1) preparing core-shell structure light-absorbing and heat-generating particles; (2) modifying the surface of ferroferric oxide@silicon dioxide particles; (3) in-situ polymerization; and (4) melt spinning. In the present application, nano-ferroferric oxide is selected as a core light-absorbing material, and its unique Fe2+ / Fe3+ mixed valence electron structure can realize wide-spectrum light absorption while hardly generating oxidative photo-generated holes, thus avoiding the photocatalytic degradation risk similar to titanium dioxide from the source and ensuring the long-term stability of the polymer matrix. In combination with in-situ polymerization, axial gradient magnetic field spinning process and the like, the water washing resistance, aging resistance and strength of the light-absorbing and heat-generating composite fiber are simultaneously improved.

Description

Technical Field

[0001] This invention relates to the field of composite fiber technology, specifically to a light-absorbing and heat-generating composite fiber and its preparation method. Background Technology

[0002] With the continuous development of functional fiber technology, light-absorbing and heat-generating fibers have gradually become a research hotspot in the field of textile materials due to their excellent warmth retention properties and broad application prospects. However, existing light-absorbing and 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 (PLA) fibers, published on December 5, 2023. This patent involves melt spinning a mixture of PLA with low-molecular-weight water-soluble polyester, high-molecular-weight water-soluble polyester, and a light-absorbing and heat-generating material to produce fibers with excellent light-absorbing and heat-generating properties, dyeability, and strength. However, in this technical solution, the light-absorbing and heat-generating material is directly mixed into the polymer matrix, which may lead to the catalytic degradation of the fiber matrix by nano-inorganic particles. This can cause functional attenuation and reduced heat generation during repeated washing, drying, or use. Furthermore, this method requires high control over the raw material ratio and zero-shear viscosity, potentially increasing process complexity and production costs. CN113215679B discloses a method for preparing light-absorbing and heat-generating polyamide-based elastic fibers, published on June 17, 2022. This patent describes a process involving the polycondensation reaction of caprolactam, aliphatic diacids, aliphatic diols, and polyethylene glycol mixed with light-absorbing and heat-generating powders, followed by melt spinning to produce elastic fibers with excellent light-absorbing and heat-generating properties. However, the method of introducing the light-absorbing and heat-generating powders in this technical solution may lead to uneven distribution within the fiber, thus affecting the consistency of heat-generating performance. Furthermore, while the addition of polyethylene glycol improves the fiber's flexibility, it may reduce the fiber's heat resistance and mechanical strength, limiting its application in high-temperature environments.

[0004] The above problems indicate that existing light-absorbing and heat-generating fibers still have certain shortcomings in terms of preparation process, functional stability, durability, and overall performance optimization. Summary of the Invention

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

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing the above-mentioned light-absorbing and heat-generating composite fiber, by weight, includes the following steps:

[0008] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0009] 0.5-3 parts of iron(III) oxide nanoparticles were dispersed in ethanol, and 0.1-0.5 parts of ammonia water were added, with the mass percentage of ammonia gas in the ammonia water being 25wt%-28wt%. Then, 1-5 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer. After washing and drying, iron(III) oxide@silica particles were obtained.

[0010] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0011] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.1-0.3 parts of silane coupling agent were added. The mixture was refluxed for 6-12 hours. Subsequently, 0.2-0.6 parts of hydroxyethyl acrylate and 0.01-0.03 parts of azobisisobutyronitrile were added, and the mixture was reacted at 70-80℃ for 4-8 hours to obtain modified iron(III) oxide@silica particles.

[0012] (3) In-situ polymerization:

[0013] 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 iron(III) oxide@silica particles and carry out transesterification reaction at 180-200℃; raise the temperature to 260-280℃ and perform vacuum polycondensation to obtain polyester melt;

[0014] (4) Melt spinning: The polyester melt is heated to 270-290℃ and extruded through a spinneret, then drawn and wound to obtain light-absorbing and heat-generating composite fibers. An axial magnetic field of 0.2-0.4T is applied during the spinning process.

[0015] This method enhances weather resistance through dual protection and chemical bonding: the silica shell physically isolates the catalytically active surface of the iron(III) oxide nanoparticles, blocking the pathways that trigger 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 debinding. This synergistic mechanism of "shell isolation + chemical bonding" ensures that the particles maintain stable dispersion and functional integrity under stresses such as washing and light exposure. Ammonia acts as a bifunctional regulator of the coating reaction in this method: the hydroxide ions it releases efficiently catalyze the hydrolysis of tetraethyl orthosilicate to generate active silanol (Si-OH), while the weakly alkaline environment (pH≈9-11) precisely inhibits the excessive polycondensation of silanol, ensuring that silica is directionally deposited on the iron(III) oxide surface at a controllable rate; in addition, ammonia molecules temporarily bind to the Fe-OH groups on the particle surface through hydrogen bonds, guiding the silanol to preferentially polycondense at the particle interface, ultimately forming a dense and uniformly thick silica isolation layer.

[0016] The fundamental reason for choosing nano-ferric oxide lies in its unique electronic structure: Fe 2+ / Fe 3+ Mixed valence states form continuous energy levels within the band gap, enabling it to possess efficient and broad-spectrum light absorption capabilities while generating almost no oxidizing photogenerated holes (unlike broad-bandgap semiconductors such as titanium dioxide), thus avoiding the risk of photocatalytic degradation of polymers at the source; its moderate magnetic responsiveness satisfies the magnetic field orientation requirements while avoiding uncontrollable aggregation caused by strong magnetism, forming a functional balance of "light absorption-magnetic control-protection" with the silicon dioxide coating layer.

[0017] Axial magnetic field refers to a magnetic field parallel to the direction of melt movement. The core value of spinning in a magnetic field lies in constraining the orientation of iron oxide nanoparticles through the axial magnetic field, causing them to arrange themselves in an orderly manner along the fiber axis, constructing a continuous photothermal 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 force much lower than the thermal motion energy of the melt molecules. The particles spontaneously disperse under the dominance of Brownian motion. The physical gaps formed by the silica coating layer block the interaction of magnetic dipoles. The fluid shear force generated by the high shear flow field of the melt has a higher disintegration strength for potential agglomerates than the magnetic force. The three factors work together to ensure dispersion stability.

[0018] The mass ratio of tetraethyl orthosilicate to iron oxide nanoparticles controls the thickness of the silica shell. The silica shell thickness is 5-10 nm. If it is too thin, the isolation will be insufficient, and if it is too thick, it will hinder light absorption.

[0019] Preferably, the silicon dioxide shell of the iron(II,III) oxide@silicon dioxide particles is a core-shell particle with a silicon dioxide shell thickness of 5-10 nm;

[0020] Preferably, the silane coupling agent in step (2) is γ-methacryloyloxypropyltrimethoxysilane.

[0021] The amount of γ-methacryloxypropyltrimethoxysilane used ensures the double bond grafting density, avoids insufficient reaction sites or surface overloading aggregation, and at the same time ensures complete double bond reaction, eliminating matrix degradation caused by residual initiator.

[0022] Preferably, in step (4), the angle θ between the direction of the axial magnetic field and the direction of melt extrusion is ≤5°.

[0023] Preferably, in step (4), the axial magnetic field of 0.2-0.4T applied during the spinning process is divided into two segments: one segment is the magnetic field B1 before the filament is ejected and the other segment is the magnetic field B2 after the filament is ejected. The magnetic fields B1 and B2 are in the same direction.

[0024] Preferably, in step (4), the magnetic field strength of magnetic field B1 is 0.3-0.4T, and is adjusted in real time according to the melt temperature.

[0025] When the melt temperature is 270-280℃, B1 is 0.3-0.35T;

[0026] When the melt temperature is >280℃, B1 is 0.35-0.4T.

[0027] Preferably, the ratio of the magnetic field strength of magnetic field B2 to that of B1 is 0.8-1.0:1.

[0028] Before the filament is ejected, it refers to the molten material being transported to the inlet of the spinneret (0-5 mm from the spinneret orifice). After the filament is ejected, it refers to the molten material leaving the outlet of the spinneret orifice.

[0029] The above scheme yielded a light-absorbing and heat-generating composite fiber, which is a polyester fiber matrix loaded with modified iron oxide@silicon dioxide particles; the modified iron oxide@silicon dioxide particles have a core-shell structure, with silicon dioxide as the shell layer.

[0030] This solution also discloses the light-absorbing and heat-generating composite fiber prepared by the above-mentioned method.

[0031] The present invention has the following advantages:

[0032] Using nano-ferric oxide as the core light-absorbing material, its unique Fe 2+ / Fe 3+ The mixed valence electronic structure achieves broad-spectrum light absorption while generating almost no oxidative photogenerated holes, thus avoiding the photocatalytic degradation risk similar to that of titanium dioxide from the source and ensuring the long-term stability of the polymer matrix.

[0033] In-situ polymerization combined with axial gradient magnetic field spinning process allows active monomers to be grafted onto the surface of the particles to form chemical bonds with the polyester, avoiding the weakening of heat resistance by adding toughening agents; the dynamic control of the magnetic field enables the particles to be precisely oriented along the fiber axis, overcoming the uneven dispersion defects caused by traditional blending, and simultaneously improving the water wash resistance, aging resistance and strength. Detailed Implementation

[0034] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0035] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0036] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0037] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0038] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0039] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron(III) oxide@silica particles.

[0040] (3) In-situ polymerization:

[0041] 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 iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0042] (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.37T.

[0043] After ejection: the magnetic field strength B2 is 0.35T. Example 2

[0044] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0045] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0046] Three parts of iron oxide nanoparticles were dispersed in ethanol, and 0.5 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 5 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 10 nm were obtained.

[0047] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0048] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.3 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 12 h. Then, 0.6 parts of hydroxyethyl acrylate and 0.03 parts of azobisisobutyronitrile were added, and the mixture was reacted at 80 °C for 8 h to obtain modified iron(III) oxide@silica particles.

[0049] (3) In-situ polymerization:

[0050] 100 parts of dimethyl terephthalate, 80 parts of ethylene glycol, and 0.05 parts of zinc acetate were mixed; then 3 parts of modified iron(III) oxide@silica particles were added, and transesterification was carried out at 200°C; the temperature was raised to 280°C, and vacuum polycondensation was performed to obtain polyester melt.

[0051] (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength in the inlet section is 0.4T.

[0052] After ejection: the magnetic field strength B2 is 0.4T. Example 3

[0053] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0054] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0055] 0.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.2 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 1 part of tetraethyl orthosilicate was added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 6 nm were obtained.

[0056] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0057] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.1 part of γ-methacryloxypropyltrimethoxysilane was added. The mixture was refluxed for 6 h. Then, 0.2 parts of hydroxyethyl acrylate and 0.01 parts of azobisisobutyronitrile were added, and the mixture was reacted at 75 °C for 4 h to obtain modified iron(III) oxide@silica particles.

[0058] (3) In-situ polymerization:

[0059] 100 parts of dimethyl terephthalate, 65 parts of ethylene glycol, and 0.02 parts of zinc acetate were mixed; then 0.5 parts of modified iron(III) oxide@silica particles were added, and transesterification was carried out at 185°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0060] (4) Melt spinning: The polyester melt is heated to 280°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.32T.

[0061] After ejection: the magnetic field strength B2 is 0.28T. Example 4

[0062] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0063] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0064] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron(III) oxide@silica particles.

[0065] (3) In-situ polymerization:

[0066] 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 iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0067] (4) Melt spinning: The polyester melt is heated to 275°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.3T.

[0068] After ejection: the magnetic field strength B2 is 0.28T.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that nano-titanium dioxide is used as the light-absorbing and heat-generating nanoparticles:

[0071] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0072] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0073] 1.5 parts of nano-titanium dioxide were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming titanium dioxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0074] (2) Surface modification of titanium dioxide@silicon dioxide particles:

[0075] One part of titanium dioxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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@silica particles.

[0076] (3) In-situ polymerization:

[0077] 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 titanium dioxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0078] (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.37T.

[0079] After ejection: the magnetic field strength B2 is 0.35T.

[0080] Comparative Example 2

[0081] The difference from Example 1 is that no core-shell structure was prepared:

[0082] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0083] (1) Surface modification of iron oxide nanoparticles:

[0084] One part of iron oxide nanoparticles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron oxide nanoparticles.

[0085] (2) In-situ polymerization:

[0086] 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 iron oxide nanoparticles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0087] (3) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.37T.

[0088] After ejection: the magnetic field strength B2 is 0.35T.

[0089] Comparative Example 3

[0090] The difference from Example 1 is that ammonia was not used:

[0091] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0092] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0093] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and then 3 parts of tetraethyl orthosilicate were added dropwise. The reaction generated a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0094] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0095] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron(III) oxide@silica particles.

[0096] (3) In-situ polymerization:

[0097] 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 iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0098] (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.37T.

[0099] After ejection: the magnetic field strength B2 is 0.35T.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that the iron(III) oxide@silicon dioxide particles were not surface modified:

[0102] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0103] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0104] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0105] (2) In-situ polymerization:

[0106] 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.03 parts of zinc acetate were mixed; then 1.5 parts of iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0107] (3) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain 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 the melt extrusion is ≤5°, and the reference value B1 of the axial magnetic field strength before extrusion is 0.37T.

[0108] After ejection: the magnetic field strength B2 is 0.35T.

[0109] Comparative Example 5

[0110] The difference from Example 1 is that spinning was not performed in a magnetic field:

[0111] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0112] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0113] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0114] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0115] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron(III) oxide@silica particles.

[0116] (3) In-situ polymerization:

[0117] 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 iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0118] Melt spinning: Polyester melt is heated to 290°C, extruded through a spinneret, spun, drawn, and wound to obtain light-absorbing and heat-generating composite fibers.

[0119] Comparative Example 6

[0120] The difference from Example 1 is that the spinning magnetic field is kept constant at 0.4T:

[0121] A method for preparing a light-absorbing and heat-generating composite fiber, comprising the following steps by weight:

[0122] (1) Preparation of core-shell structured light-absorbing and heat-generating particles:

[0123] 1.5 parts of iron oxide nanoparticles were dispersed in ethanol, and 0.3 parts of ammonia water were added, with the mass percentage of ammonia in the ammonia water being 25 wt%. Then, 3 parts of tetraethyl orthosilicate were added dropwise to react and generate a silica coating layer, forming iron oxide@silica particles. After washing and drying, core-shell particles with a silica shell thickness of 8 nm were obtained.

[0124] (2) Surface modification of iron(II,III) oxide@silicon dioxide particles:

[0125] One part of iron(III) oxide@silica particles was dispersed in toluene, and 0.2 parts of γ-methacryloxypropyltrimethoxysilane were added. The mixture was refluxed for 8 hours. Then, 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 iron(III) oxide@silica particles.

[0126] (3) In-situ polymerization:

[0127] 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 iron(III) oxide@silica particles were added, and transesterification was carried out at 190°C; the temperature was raised to 270°C, and vacuum polycondensation was performed to obtain polyester melt.

[0128] (4) Melt spinning: The polyester melt is heated to 290°C and extruded through a spinneret, spun, drawn and wound to obtain light-absorbing and heat-generating composite fiber; an axial magnetic field of 0.4T is applied during the spinning process; the angle θ between the direction of the axial magnetic field and the direction of the melt extrusion is ≤5°, and the strength of the axial magnetic field is 0.4T before and after the extrusion.

[0129] Performance testing:

[0130] Light absorption and heat generation performance test: The surface temperature rise of the fiber was measured in accordance with GB / T18319-2019 standard. The temperature rise value ΔT = (temperature after 10 minutes of light exposure) - (initial temperature).

[0131] Water washing test: Refer to AATCC135-2018, 50 cycles (40℃, 0.5% soap solution);

[0132] UV aging: Referring to ISO4892-3, using a UVB light source (0.76W / m²), irradiation for 500 hours, performance retention rate = (ΔT after aging / initial ΔT) × 100%;

[0133] Mechanical properties: Fracture strength refers to GB / T14344-2008 (tensile rate 20mm / min).

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] Comparing Examples 1-4 with 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 maintain it for a longer period of time, and has better weather resistance and water washability.

[0138] In Comparative Example 1, TiO2 was used instead of Fe3O4, compared to Example 1. The core advantage of using nano-ferric oxide in Example 1 lies in its mixed valence electronic structure. 2+ / Fe 3+ The continuous energy levels formed in the band gap enable it to have a wide spectrum of light absorption capabilities, while generating almost no highly oxidizing photogenerated holes. This fundamentally avoids the risk of polymer chain breakage caused by ultraviolet light in wide band gap semiconductors such as titanium dioxide, thus ensuring long-term photostability.

[0139] Comparative Example 2, compared to 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 iron oxide particles, blocking the Fenton reaction catalytic pathway initiated by Fe ion dissolution, effectively inhibiting the hydrolytic degradation of ethylene glycol end groups during water washing, and maintaining the integrity of the polymer matrix.

[0140] Compared to Example 1, Comparative Example 3 shows that ammonia-free water treatment of ammonia water in Example 1 plays a dual-function regulatory role: the OH groups it releases... - Ion-catalyzed controlled hydrolysis of tetraethyl orthosilicate, while NH3 molecules guide the directional deposition of silanols onto the particle surface via hydrogen bonds. This mechanism ensures the formation of a uniformly thick silica insulating layer, preventing pitting corrosion caused by localized protective failure.

[0141] Compared to Example 1, Comparative Example 4, without surface modification, resulted in the formation of polymer chains containing active hydroxyl groups on the particle surface. During polycondensation, these hydroxyl groups form covalent ester bonds with polyester carboxyl groups, anchoring the particles to the molecular chain network, significantly enhancing interfacial adhesion, and suppressing interfacial debonding under washing stress.

[0142] Comparative Example 5 is a non-magnetic spinning process compared to Example 1. In Example 1, an axial gradient magnetic field was used to construct a magnetorheological synergistic orientation mechanism. The magnetic force induced weakly magnetic particles to align oriented along the melt flow direction, resulting in a more regular molecular arrangement after fiber cooling.

[0143] Compared to Example 1, Comparative Example 6 used a constant magnetic field during the spinning process. The gradient magnetic field design of Example 1 overcame the rheological adaptation defects of a constant magnetic field. A lower field strength at the inlet section prevented excessive shearing of the high-viscosity melt, while a higher field strength in the middle section strengthened particle orientation to counteract molecular chain relaxation. A lower field strength at the outlet section prevented stress concentration in the solidification zone, achieving a balance between orientation and processing stability. Although Comparative Example 6's performance was not as good as Examples 1-4, it still exhibited better durability and weather resistance compared to the other comparative examples.

Claims

1. A method for preparing a light-absorbing and heat-generating composite fiber, characterized in that, The method comprises the following steps: The weight parts are counted, (1) Preparation of core-shell structure light-absorbing and heat-generating particles: 0.5-3 parts of ferroferric oxide nanoparticles are dispersed in ethanol, and 0.1-0.5 parts of ammonia water are added; then 1-5 parts of tetraethyl orthosilicate are added dropwise, and a silica coating layer is generated by reaction, and the ferroferric oxide@silica particles are obtained by washing and drying; (2) Surface modification of ferroferric oxide@silica particles: 1 part of ferroferric oxide@silica particles is dispersed in toluene, 0.1-0.3 parts of γ-methacryloxypropyltrimethoxysilane is added, and reflux reaction is carried out for 6-12 h; then 0.2-0.6 parts of hydroxyethyl acrylate and 0.01-0.03 parts of azobisisobutyronitrile are added, and reaction is carried out at 70-80°C for 4-8 h to obtain modified ferroferric oxide@silica particles; (3) In-situ polymerization: 100 parts of dimethyl terephthalate, 60-80 parts of ethylene glycol, and 0.01-0.05 parts of zinc acetate are mixed; then 0.5-3 parts of modified ferroferric oxide@silica particles are added, and ester exchange reaction is carried out at 180-200°C; the temperature is raised to 260-280°C, and vacuum polycondensation is carried out to obtain a polyester melt; (4) Melt spinning: The polyester melt is heated to 270-290°C, extruded, drawn, and wound through the spinneret to prepare light-absorbing and heat-generating composite fibers, and an axial magnetic field of 0.2-0.4 T is applied during the spinning process.

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

3. The method for producing light-absorbing heat-generating composite fiber according to claim 1, wherein In step (4), the direction of the axial magnetic field has an angle θ of ≤5° with the extrusion direction of the melt.

4. The method of producing light-absorbing 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 magnetic field B1 before the spinning is discharged and magnetic field B2 after the spinning is discharged.

5. The method of producing light-absorbing heat generating composite fiber according to claim 1, wherein The magnetic field strength of 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°C, B1 is 0.3-0.35 T; When the melt temperature is >280°C, B1 is 0.35-0.4 T.

6. The method for producing light-absorbing heat generating composite fiber according to claim 5, wherein The ratio of the magnetic field strength of magnetic field B2 to B1 is 0.8-1.0:

1.

7. A light-absorbing and heat-generating composite fiber prepared by the method of any one of claims 1-6.

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