CN111663198A

CN111663198A - Micro-nano magnetic fiber and preparation method thereof

Info

Publication number: CN111663198A
Application number: CN202010567156.3A
Authority: CN
Inventors: 陶光明; 王蕊; 向远卓; 马庶祺; 曾少宁
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2020-09-15
Anticipated expiration: 2040-06-19
Also published as: CN113718368B; WO2021254495A1; CN113718368A; CN111663198B

Abstract

Disclosed is a method for preparing micro-nano magnetic fibers, wherein the micro-nano magnetic fibers comprise a core layer, and the method comprises the following steps: compounding: compounding the magnetic particles with a base material to obtain a magnetic composite material; processing: preparing a magnetic structured preform by using a magnetic composite material; hot drawing: and preparing the magnetic structured prefabricated rod into the micro-nano magnetic fiber by adopting a hot drawing process. The micro-nano magnetic fiber comprises a core layer, wherein the core layer comprises magnetic particles and a base material, and the magnetic particles are distributed in the base material; the magnetic particles are selected from one or more than two of the following: metal magnetic particles, metal compound magnetic particles, metal alloy magnetic particles; the base material is selected from one or more than two of the following materials: polymers, inorganic glass materials and composites thereof. The method has universality for the composite integration of a plurality of magnetic materials, magnetic composite materials and other functional materials, and has regulation and control capability on the concentration, distribution, structure and fiber diameter of magnetic particles in the prepared micro-nano magnetic fiber.

Description

Micro-nano magnetic fiber and preparation method thereof

Technical Field

The application relates to the field of functional fibers, in particular to a micro-nano magnetic fiber and a preparation method thereof.

Background

Magnetic materials are widely used in biomedical, wearable, soft actuation, flexible actuation, environmental remediation, etc. due to their high mechanical and electrical responsiveness to magnetic fields, and have become a research hotspot in recent years. The fibrous form is a material form, exists in every aspect of our daily life, and is an excellent technical carrier. How to integrate various magnetic materials (including hard magnetic materials and soft magnetic materials) into fibers in a highly controllable manner in terms of distribution, concentration and structure is the key to introducing magnetic functions into applications such as soft robots, smart materials, biomedicine and the like.

Patent document 1 discloses a magnetic self-assembled mesoporous fiber and a preparation method thereof. The method utilizes a sol-gel method to assemble magnetic substances on mesoporous fibers in situ, and mainly comprises the steps of precursor liquid containing metal salt and silicon, spinning or spinning and high-temperature sintering. The weight ratio of the magnetic substance is 5-60%.

Patent document 2 discloses a method for producing a highly efficient magnetic carbon nanocomposite for treating chromium-containing wastewater. Combining the electrostatic spinning technology and the high-temperature calcining technology, the fiber preparation steps comprise the graft modification of polystyrene, the electrostatic spinning of modified polystyrene fiber, the infiltration of ferric nitrate nonahydrate/absolute ethyl alcohol solution, drying and calcining. The diameter of the fiber is 0.5 to 2 microns. Wherein the concentration of the ferric nitrate nonahydrate/absolute ethyl alcohol solution is 4-7%.

Patent document 3 discloses Fe₃O₄A preparation method of a fungal fiber magnetic composite material. The steps comprise nano Fe₃O₄Preparation of (1), fungal fiber and Fe₃O₄The hydrothermal synthesis of (2). Nano Fe₃O₄Uniformly dispersed on the surface of the fungal fiber,the composite material has good paramagnetism. Wherein, the fungal fiber and the nano Fe₃O₄The dosage ratio of the particles is 1: 0-5: 1

Patent documents 1 to 3 are all based on the production of magnetic fibers by a chemical method. Due to the dynamic characteristics of chemical reaction, the components, the sizes and the distribution heights of the magnetic particles in the prepared magnetic fibers are not controllable, and meanwhile, the content of the magnetic particles is low, and the method is difficult to be widely applied to various magnetic materials and polymers.

Patent document 4 discloses a one-dimensional magnetic fiber material and a method for producing the same. The fiber consists of a shell layer and a core layer and is prepared by a high-voltage electrostatic spinning method. The shell layer is made of p-type semiconductor polymer poly-p-phenylene vinylene as main material, the thickness is 30-150 nm, and the core layer is made of magnetic Fe₃O₄The nano particles and a polyvinyl alcohol dispersion medium, and the particle size is 5-30 nm. The average diameter of the magnetic nano-fiber is 100-450 nm, and the length of the magnetic nano-fiber is 10 mu m-10 cm. The magnetic Fe₃O₄The mass percentage of the nano particles is 2-56%. Patent document 4 discloses a method for producing magnetic nanofibers having a core-shell structure by an electrospinning technique. Due to the dynamic characteristics and the conductivity requirements of the electrostatic spinning technology, the diameter of the fiber is limited to hundreds of microns, the length of the fiber is discontinuous, and the fiber outer cladding layer has certain conductivity, so that the application range of the magnetic nanofiber is limited to a great extent.

Patent document 5 discloses a magnetic glass fiber and a method for producing the same. The magnetic glass fiber is composed of 2-13 wt.% of nano-scale ferrite magnetic powder (CoFe)₂O₄,BaFe₁₂O₁₉,NiFe₂O₄) And quartz glass (SiO)₂) The mixed material is obtained by wire drawing and has obvious magnetic property.

Patent document 6 discloses a method for producing magnetic nanocomposite particles and magnetic fibers thereof. The preparation method comprises the steps of preparing nano-cellulose, preparing magnetic nano-composite particles, mixing the magnetic nano-composite particles with carrier resin, mixing with raw material resin, and carrying out melt spinning. The fiber shows higher paramagnetic response and has good mechanical property. The invention is magneticThe nano-composite particles are Fe₃O₄The magnetic fiber accounts for 5-30% of the magnetic fiber by mass.

Patent document 7 discloses a method for producing a magnetic field-responsive fiber. The steps include Fe₃O₄Preparation of nano-microspheres and Fe₃O₄Preparing PDMS macromolecule monomer emulsion, and curing and molding the fiber based on the glass capillary template. Due to mixed Fe₃O₄The mass ratio of the nano microspheres is very low (<1 wt.%), the fiber produced can turn red under an applied magnetic field.

Patent document 8 discloses a magnetic fiber and a method for producing the same. The fiber has a sheath-core structure, is obtained by carrying out composite spinning on a sheath material and a core material extruded by uniformly mixing double screws, and has a sheath-core weight ratio of 3: 7-7: 3. the skin layer material comprises 57-89.7% of polymer, 10-40% of magnetic powder and 0.3-3% of compatibilizer, and the core layer material comprises 80-97.5% of polymer, 2-15% of metal powder and 0.5-5% of coupling agent.

Patent document 9 discloses a method for producing a nanofiber membrane having hard magnetic properties. The fiber preparation steps comprise: demagnetizing magnetic nanoparticles, mixing and compounding the demagnetized magnetic nanoparticles with ethylene-vinyl alcohol copolymer, composite spinning and extracting. The magnetic nanoparticles (10-100 nm) are SrFe₁₂O₁₉、Fe₃O₄、Nd₂Fe₁₄B. The mass percentage of the magnetic nanoparticles is 5-20%.

Patent document 10 discloses a magnetic field-induced auxiliary spinning forming device for conductive/magnetic conductive chemical fibers and a production method thereof. The fiber mixed melt precursor is obtained by melting and blending magnetic powder, a dispersing agent, an antioxidant and a polymer, magnetic particles in the mixed melt are arranged in the direction of magnetic lines of force to form a microfiber or a bead structure under the action of a magnetic field generated by an electromagnetic coil arranged on a spinning head, a strand silk is cooled and solidified, and then the fiber is obtained by oiling, bundling, drafting and heat setting. Wherein the magnetic field intensity is controlled to be 0.01-2T, and the magnetic powder is Fe, Ni, Co metal or alloy or ferrite with the content of 1-20 wt.%.

Patent document 11 discloses a method for producing a magnetorheological elastomer having programmable magnetic deformation. And printing the magnetic short fibers with specific distribution and orientation by a 3D printer integrated with a pre-structured magnetic field. The magnetic short fibers have random distribution and orientation. The pre-structure magnetic field is 100-500 mT. The magnetic particles are carboxyl iron powder or NdFeB particles, the content of the magnetic particles is 10-49.5 wt.%,

patent documents 5 to 11 each perform the production of a magnetic fiber based on a thermal method (including melt composite spinning, a drawing technique, and a 3D printing technique). However, no technology has been available for the application of most magnetic materials, including hard magnetic materials and soft magnetic materials. Meanwhile, due to the essential characteristics of the rheological dynamics, the content of the magnetic material particles or the magnetic composite material particles in the magnetic fiber obtained by the technology is generally lower than 50 wt.%, and the diameter of the magnetic particles which can be integrated in the fiber and the regulation and control capability of the structure and the diameter of the fiber are also very limited.

Documents of the prior art

Patent document 1 CN102041584B publication document

Patent document 2 CN106732376B publication document

Patent document 3 CN107670648B publication document

Patent document 4 CN101768797A publication

Patent document 5 CN100340510C publication document

Patent document 6 CN102978728A publication

Patent document 7 CN104278352B publication text

Patent document 8 CN101649503B publication document

Patent document 9 CN106000116B publication document

Patent document 10 CN104963018B publication document

Patent document 11 CN109818523B publication document

Content of application

In order to solve the problems of single magnetic function and other functions, low magnetic conversion capacity, poor mechanical performance and the like of magnetic fibers in the prior art, the application provides the micro-nano magnetic fiber and the preparation method of the micro-nano magnetic fiber, which have universality on the composite integration of most magnetic materials, magnetic composite materials and other functional materials and have the capability of regulating and controlling the integrated concentration, distribution, structure and fiber diameter of particles in the fiber.

The specific technical scheme of the application is as follows:

1. a preparation method of micro-nano magnetic fibers is characterized in that the micro-nano magnetic fibers comprise a core layer, and the preparation method comprises the following steps:

compounding: compounding the magnetic particles with a base material to obtain a magnetic composite material;

processing: preparing a magnetic structured preform from the magnetic composite material;

hot drawing: and preparing the magnetic structured prefabricated rod into the micro-nano magnetic fiber by adopting a hot drawing process.

2. The method for preparing micro-nano magnetic fiber according to item 1, characterized in that,

in the compounding step, compounding the magnetic particles with a base material to obtain a plurality of magnetic composite materials;

in the processing step, the plurality of magnetic composite materials are utilized to prepare the magnetic structured preform.

3. The method for preparing the micro-nano magnetic fiber according to the

item

1 or 2, wherein the micro-nano magnetic fiber comprises a core layer and a cladding layer;

in the processing step, the magnetic structured preform is prepared by using the magnetic composite material and the material of the cladding.

4. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 3, wherein the micro-nano magnetic fiber further comprises a high-melting-point functional layer;

in the hot drawing step, the magnetic structural prefabricated rod wraps the material of the high-melting-point functional layer, and the micro-nano magnetic fiber is prepared by adopting a hot drawing process in mechanical synchronization with the material of the high-melting-point functional layer.

5. The method for preparing the micro-nano magnetic fiber according to any one of items 1 to 4, wherein in the processing step, the magnetic structured preform is prepared by one or more methods selected from a film winding method, a thermal pressing method, an extrusion molding method and a 3D printing method.

6. The method for preparing the micro-nano magnetic fiber according to the item 5, wherein in the processing step, the method for preparing the magnetic structured preform further comprises one or more of the following methods: machining, assembling and thermosetting.

7. The method for preparing the micro-nano magnetic fiber according to the

item

5 or 6, characterized by further comprising the following steps after the thermal drawing step:

secondary processing: preparing a second magnetic structured preform by using the micro-nano magnetic fibers;

secondary hot drawing: preparing the second magnetic structural prefabricated rod into a second micro-nano magnetic fiber by adopting a hot drawing process;

preferably, in the secondary processing step, the second magnetically structured preform is prepared by a 3D printing method.

8. The method for preparing the micro-nano magnetic fiber according to any one of items 1 to 7, wherein in the compounding step, the magnetic composite material is magnetic composite material particles, a magnetic composite material film or magnetic composite material powder.

9. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 8, wherein in the compounding step, the magnetic particles and the base material are compounded by a chemical method;

preferably, the chemical process comprises the steps of: chemical dissolution of the substrate, doping of the magnetic particles and ultrasonic dispersion;

more preferably, the chemical method further comprises vacuum drying after the ultrasonic dispersion step.

10. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 8, wherein in the compounding step, the magnetic particles and the base material are compounded by a physical method;

preferably, the physical method comprises the steps of: physical thermal melting of the substrate, doping and extrusion of the magnetic particles.

11. The method for preparing the micro-nano magnetic fiber according to any one of the items 10, wherein in the compounding step, the magnetic particles are selected from one or more than two of the following: metal magnetic particles, metal compound magnetic particles, metal alloy magnetic particles;

preferably, the metal magnetic particles are selected from one or more of the following: ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles;

preferably, the metal compound magnetic particles are metal oxide magnetic particles; more preferably, the metal compound magnetic particles are selected from one or two of: fe₃O₄Magnetic particles, gamma-Fe₂O₃Magnetic particles;

preferably, the metal alloy magnetic particles are selected from one or more of the following: neodymium iron boron alloy magnetic particles, samarium cobalt alloy magnetic particles, nickel cobalt alloy magnetic particles, and iron cobalt alloy magnetic particles.

12. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 11, wherein the diameter of the magnetic particles is 0.005 to 250 μm, preferably 0.005 to 100 μm.

13. The preparation method of the micro-nano magnetic fiber according to any one of items 1 to 12, wherein the base material is selected from one or more than two of the following materials: polymers, inorganic glass materials and composites thereof.

14. The method for preparing a micro-nano magnetic fiber according to item 13, wherein the polymer is a thermoplastic polymer;

preferably, the polymer is selected from one or two or more of: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether;

preferably, the glass is selected from one or two or more of the following: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

15. The method for preparing micro-nano magnetic fiber according to the item 9, wherein the solvent used for chemical dissolution of the base material is one or more than two of the following solvents: acetone, butanone, N-methylpyrrolidone, Dimethylacetamide (DMAC), Dimethylformamide (DMF), chloroform, cyclohexane, toluene, ethylbenzene, cumene, xylene, bromobenzene, chlorobenzene, dichloromethane, dichloroethane, tetrachloroethane, tetrachloroethylene, styrene, limonene solvent, ethyl acetate, butyl acetate.

16. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 15, wherein the base material, the magnetic composite material and the micro-nano magnetic fiber are dried in vacuum before use;

the vacuum drying temperature is 20-300 ℃, and preferably 60-150 ℃;

the vacuum drying time is 2-2000 hours, preferably 12-50 hours.

17. The method for preparing the micro-nano magnetic fiber according to any one of the items 3 to 16, wherein the cladding comprises a base material, and the base material is selected from one or more than two of the following materials: polymers, inorganic glass materials and composites thereof; the coefficient of thermal expansion of the material of the cladding matches the coefficient of thermal expansion of the magnetic composite material; or the glass transition temperature or melting point of the material of the cladding matches the glass transition temperature or melting point of the magnetic composite material;

preferably, the glass is selected from one or two or more of the following: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses;

preferably, the cladding further comprises magnetic particles, and the magnetic particles are compounded with the base material to obtain the material of the cladding.

18. The method for preparing the micro-nano magnetic fiber according to the

item

5 or 6, wherein the magnetic composite material is a magnetic composite material film, the magnetic composite material film is processed by a film winding method, and the Young modulus of the magnetic composite material film is 0.01-1 GPa.

19. The method for preparing the micro-nano magnetic fiber according to the

item

5 or 6, characterized in that the micro-nano magnetic fiber is processed by a hot pressing method, and the hot pressing temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material;

preferably, the hot pressing temperature is 25-600 ℃, and further preferably 120-250 ℃;

preferably, the hot pressing time is 5-600 min, and more preferably 10-20 min.

20. The method for preparing the micro-nano magnetic fiber according to the

item

5 or 6, characterized in that the micro-nano magnetic fiber is processed by an extrusion molding method, wherein the extrusion temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material;

preferably, the extrusion temperature is 50-700 ℃, and more preferably 200-400 ℃.

21. The method for preparing the micro-nano magnetic fiber according to the

item

5 or 6, characterized in that the micro-nano magnetic fiber is processed by a 3D printing method, and the printing temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material;

preferably, the printing temperature is 50-700 ℃, and more preferably 200-400 ℃.

22. The method for preparing the micro-nano magnetic fiber according to the item 6, which is characterized in that the micro-nano magnetic fiber is processed by a thermosetting method, wherein the curing temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material;

preferably, the curing temperature is 50-500 ℃, and further preferably 150-300 ℃;

preferably, the curing time is 1 to 500min, and more preferably 20 to 40 min.

23. The method for preparing the micro-nano magnetic fiber according to any one of items 1 to 22, wherein the temperature of the hot drawing process is 25 to 600 ℃, preferably 230 to 400 ℃.

24. The method for preparing the micro-nano magnetic fiber according to any one of the items 1 to 23, wherein the tension of the hot drawing process is 0 to 500g, preferably 10 to 50 g;

preferably, the drawing speed of the hot drawing process is 0.1m/min to 5000 m/min.

25. The method for preparing the micro-nano magnetic fiber according to any one of items 1 to 24, wherein the glass transition temperature and the melting point of the material of the high-melting-point functional layer are respectively higher than those of the magnetic composite material, and the material of the high-melting-point functional layer is a fibrous material or a material capable of being processed into a fibrous state.

26. The method for preparing the micro-nano magnetic fiber according to any one of items 1 to 23, wherein the mass percentage of the magnetic particles in the various magnetic composite materials is 0.01 wt.% to 75 wt.%.

27. The micro-nano magnetic fiber is characterized by comprising a core layer, wherein the core layer comprises magnetic particles and a base material, and the magnetic particles are distributed in the base material;

the magnetic particles are selected from one or more than two of the following: metal magnetic particles, metal compound magnetic particles, metal alloy magnetic particles;

the base material is selected from one or more than two of the following materials: polymers, inorganic glass materials and composites thereof.

28. The micro-nano magnetic fiber according to item 27, wherein the polymer is a thermoplastic polymer;

preferably, the thermoplastic polymer is selected from one or two or more of the following: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether.

29. The micro-nano magnetic fiber according to claim 27 or 28, wherein the glass is selected from one or more than two of: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

30. The micro-nano magnetic fiber according to any one of claims 27 to 29, wherein the metal magnetic particles are selected from one or more of the following: ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles;

31. The micro-nano magnetic fiber according to any one of claims 27 to 30, wherein the diameter of the magnetic particles is 0.005 to 250 μm, preferably 0.005 to 100 μm.

32. The micro-nano magnetic fiber according to any one of claims 27 to 31, wherein the micro-nano magnetic fiber is of a columnar structure.

33. The micro-nano magnetic fiber according to any one of the claims 27 to 32, wherein the cross section of the micro-nano magnetic fiber is selected from one or more than two of the following types: circular, triangular, rectangular, polygonal, irregular.

34. The micro-nano magnetic fiber according to any one of the items 27 to 33, wherein the diameter of the micro-nano magnetic fiber is 0.01 to 3000 μm, preferably 50 to 1000 μm.

35. The micro-nano magnetic fiber according to any one of claims 27 to 34, wherein the core layer is of a multilayer structure from inside to outside, and the magnetic particles are uniformly distributed in any one layer of the core layer.

36. The micro-nano magnetic fiber according to item 35, wherein the mass percentage of the magnetic particles in at least two layers is different in comparison with each layer in the multiple layers of the core layer.

37. The micro-nano magnetic fiber according to claim 35 or 36, wherein the mass percentage of the magnetic particles in each layer is gradually decreased or gradually increased or non-monotonously changed from inside to outside in comparison with each layer in the plurality of layers of the core layer.

38. The micro-nano magnetic fiber according to any one of items 35 to 37, wherein the magnetic particles are present in each of the multiple layers of the core layer in an amount of 0.01 wt.% to 75 wt.%, preferably 1 wt.% to 75 wt.%.

39. The micro-nano magnetic fiber according to any one of claims 27 to 34, wherein the cross section of the core layer is circular, rectangular, triangular or irregular, and the cross section is divided into two or more regions, so that the core layer is divided into two or more strip-shaped structures, the magnetic particles are uniformly distributed in the strip-shaped structures in any one strip-shaped structure, and the mass percentage of the magnetic particles in at least two strip-shaped structures is different.

40. The micro-nano magnetic fiber according to item 39, wherein the cross section of the core layer is circular, and the cross section is divided into two or more than three sector-shaped regions; optionally, the cross-section is divided into two equal semi-circular areas.

41. The micro-nano magnetic fiber according to item 39, wherein the cross section of the core layer is rectangular, and the cross section is divided into two equal rectangular areas.

42. The micro-nano magnetic fiber according to item 39, wherein the cross section of the core layer is triangular, and the cross section is divided into two triangular regions.

43. The micro-nano magnetic fiber according to any one of items 39 to 42, wherein the mass percentage of the magnetic particles in each strip-shaped structure is 0.01 wt.% to 75 wt.%, and more preferably 1 wt.% to 75 wt.%.

44. The micro-nano magnetic fiber according to any one of claims 27 to 43, further comprising a high-melting-point functional layer, wherein the core layer wraps the high-melting-point functional layer;

preferably, the glass transition temperature and the melting point of the material of the high-melting-point functional layer are respectively higher than those of the material of the core layer, and the material of the high-melting-point functional layer is a fibrous material or a material capable of being processed into a fibrous state.

45. The micro-nano magnetic fiber according to any one of claims 27 to 44, further comprising a cladding, wherein the cladding comprises a base material, and the base material is selected from one or more of the following materials: polymers, inorganic glass materials and composites thereof; the material of the cladding layer and the material of the core layer can be jointly thermally drawn, and the cladding layer wraps the core layer;

preferably, the coefficient of thermal expansion of the material of the cladding layer matches the coefficient of thermal expansion of the material of the core layer; or the glass transition temperature and the melting point of the material of the cladding layer are respectively lower than the glass transition temperature and the melting point of the material of the core layer;

46. The micro-nano magnetic fiber according to item 45, wherein the core layer comprises two or more than three strip-shaped structures, and the two or more than three strip-shaped structures are mutually discrete.

47. The micro-nano magnetic fiber according to item 45, wherein the two or more than three strip-shaped structures have different mass percentages of the magnetic particles.

48. The micro-nano magnetic fiber according to any one of items 45 to 47, wherein the mass percentage of the magnetic particles in each strip-shaped structure is 0.01 wt.% to 75 wt.%, preferably 1 wt.% to 75 wt.%.

49. The micro-nano magnetic fiber prepared by the preparation method of the micro-nano magnetic fiber according to any one of items 1 to 26.

Effect of application

The application provides a preparation method of micro-nano magnetic fiber (can be simply referred to as "fibre"), for current magnetic fiber preparation method, magnetic material and substrate selective range are wide, the structural design degree of freedom is high, the structure is highly controllable, can design the prefabricated stick of different cross section structures, can accurately design the distribution of different magnetic particles and other functional materials in micro-nano magnetic fiber, thereby draw the hot micro-nano magnetic fiber who makes different structures, micro-nano magnetic fiber preparation method and micro-nano magnetic fiber that this application provided, compare with prior art, following beneficial effect has:

(1) the magnetic particles and the base material have wide selection range, the structural design freedom degree is high, the structural height is controllable, and the magnetic structural prefabricated rods with different cross section structures can be designed;

(2) the diameter regulation range of the prepared micro-nano magnetic fiber is wide and is 0.01-3000 mu m, the diameter is uniform and controllable, and the error range of the diameter size is +/-1%;

(3) the doping concentration of the magnetic particles is high, and can be accurately regulated and controlled within the range of 0.01-75 wt.%;

(4) the cross section structure of the prepared micro-nano magnetic fiber can be adjusted at will, so that the heights of continuous and discrete magnetic domain distribution, magnetic structural response and the like in the cross section are controllable, and meanwhile, the prepared micro-nano magnetic fiber has good flexibility and high magnetic force conversion efficiency;

(5) the distribution of different magnetic particles and other functional materials in the micro-nano magnetic fiber can be accurately designed, so that the micro-nano magnetic fiber with different structures can be thermally drawn, and the integration of magnetic control actuation, light guide, electric signal acquisition, magnetoelectric conversion and high-strength mechanical properties can be realized;

(6) the hot drawing process adopted by the application is a process with higher industrial maturity, and is easy to realize mass and large-scale production under the condition of lower equipment modification cost.

(7) The micro-nano magnetic fiber provides a basis for magnetic functional fiber devices oriented to biomedical treatment, wearable, flexible actuation and soft actuation, and shows huge application prospect and value in the fields of medical treatment, civil use and military use.

Drawings

Fig. 1 is a schematic view of an apparatus for preparing micro-nano magnetic fibers by using a thermal drawing process according to an embodiment of the present application.

Fig. 2A is a schematic circular cross-sectional view of a micro-nano magnetic fiber doped with single-concentration magnetic particles according to an embodiment of the present application.

Fig. 2B is a schematic view of a rectangular cross section of a micro-nano magnetic fiber doped with single-concentration magnetic particles according to an embodiment of the present application.

Fig. 2C is a schematic cross-sectional view of a single-concentration magnetic particle-doped micro-nano magnetic fiber in a triangular shape according to an embodiment of the present disclosure.

Fig. 3A is a schematic view of a circular cross section of a micro-nano magnetic fiber with a multi-layer core layer according to an embodiment of the present application.

Fig. 3B is a schematic view of a rectangular cross section of a micro-nano magnetic fiber with a multi-layer core layer according to an embodiment of the present application.

Fig. 3C is a schematic cross-sectional view of a micro-nano magnetic fiber with a multi-layer core layer according to an embodiment of the present application.

Fig. 4A is a schematic view of a circular cross section of a micro-nano magnetic fiber having two core layers with a strip structure and including a cladding layer according to an embodiment of the present application.

Fig. 4B is a schematic view of a rectangular cross section of the micro-nano magnetic fiber having two core layers with a strip structure and including a cladding layer according to an embodiment of the present application.

Fig. 4C is a schematic cross-sectional view of a triangular micro-nano magnetic fiber having two core layers with a strip structure and including a cladding layer according to an embodiment of the present application.

Fig. 4D is a schematic diagram of a circular cross section of the micro-nano magnetic fiber having two core layers with a strip structure and including a cladding layer according to an embodiment of the present application.

Fig. 4E is a schematic diagram of a rectangular cross section of the micro-nano magnetic fiber having a plurality of core layers with a strip structure and including a cladding layer according to an embodiment of the present application.

Fig. 4F is a schematic cross-sectional view of a micro-nano magnetic fiber with a core layer having six strip structures according to an embodiment of the present application.

Fig. 5 is a schematic view of a circular cross section of a micro-nano magnetic fiber integrated with a quartz optical fiber (white) and a metal electrode (black) according to an embodiment of the present application.

Fig. 6 is a schematic view of a circular cross section of a micro-nano magnetic fiber having a core layer with two discrete stripe structures and including a cladding layer according to an embodiment of the present application.

Description of the symbols

1 prefabricated excellent 2 prefabricated excellent anchor clamps

3 fiber laser diameter measuring instrument for heating furnace of wire drawing tower

Traction device of 5 wire drawing tower and fiber collecting device of 6 wire drawing tower

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The meaning of the terms herein are as follows:

the magnetic particles are permanent magnetic or soft magnetic micro-nano particles.

The structural structure refers to that the cross section of the prepared micro-nano magnetic fiber can be prepared into any required structure, such as a single-concentration magnetic particle doped structure, a multi-concentration magnetic particle doped structure, a cladding-containing structure, a cladding-free structure, a high-melting-point functional material layer-containing structure and the like; and the cross-section of the fiber can be of any shape.

A "preform" is a preform of material that can be used to draw a fiber, the structure of which determines the structure of the fiber.

"hot drawing" means heating a partial region of a preform by a heat source to soften the preform and then manually or mechanically drawing the preform from one or both ends of the heated region, and is also called "hot drawing".

The 'co-drawing functional material' refers to a material which has material parameters, thermal expansion coefficient, softening temperature and the like matched with the magnetic composite material and can be hot-drawn together with the magnetic composite material into the micro-nano magnetic fiber.

The "coefficient of thermal expansion of the material" means that the material has expansion and contraction phenomena due to temperature change, and the coefficient of thermal expansion of the materials is matched, which means that different materials have the same or close to the same coefficient of thermal expansion. Matching of the thermal expansion coefficients of the materials ensures the consistency of the fiber structure with the preform structure.

The "glass transition temperature" refers to the lowest temperature at which molecular segments in an amorphous material can move, and the hot-drawing process microscopically shows the movement of the molecular chains of the material, so that the hot-drawing temperature is higher than the glass transition temperature. By glass transition temperature matched is meant that different materials have the same or close glass transition temperature, ensuring that the different materials can be hot drawn together into a fiber.

By "melt-matched" is meant that the functional material has a melting point near or above the glass transition temperature of the amorphous material used to ensure that the functional material is capable of forming a fiber with the amorphous material at the fiber hot-draw temperature.

By "mechanically synchronized" is meant that during the hot drawing process, the magnetically structured preform is drawn synchronously with the material of the high melting point functional layer at the same draw speed.

The "thermoplastic polymer" refers to a polymer which can be melted by repeated heating, molded in a softened or fluid state, and cooled to maintain the shape of a mold, and is a linear or high molecular compound containing a small amount of branched structures.

The PMMA is polymethyl methacrylate, has the advantages of high transparency, low price, easy machining and the like, and is a frequently used glass substitute material.

"SMMA" is a styrene methyl dimethacrylate copolymer, a polyacrylic copolymer.

"COC" is a cyclic olefin copolymer, a high value-added thermoplastic engineering plastic obtained by polymerizing cyclic olefins, and is widely used for manufacturing various optical, information, electric and medical materials because of its high transparency, low dielectric constant, excellent heat resistance, chemical resistance, melt flowability, barrier properties, dimensional stability, and the like.

The COP is a cycloolefin polymer, is used for medical optical parts and high-end medicine packaging materials, and has the following raw material characteristics: high transparency, low birefringence, low water absorption, high rigidity, high heat resistance, good vapor tightness and composite FDA standard.

"PC" is a polycarbonate, a high molecular polymer containing carbonate groups in its molecular chain, and is classified into various types such as aliphatic, aromatic, aliphatic-aromatic, and the like, depending on the structure of the ester groups.

"PPSU" is a polyphenylene sulfone resin, an amorphous thermoplastic, with high transparency and high hydrolytic stability.

"PES" is polyethersulfone, usually amorphous polymer, which has better melt processability and lower melt viscosity, smaller molding shrinkage (only about 0.6%), and better dimensional stability than polysulfone.

"PEI" is polyetherimide, a super engineering plastic made of amorphous polyetherimides, has the best high temperature resistance and dimensional stability, chemical resistance, flame retardance, electrical property, high strength, high rigidity and the like, and can be widely applied to high temperature resistant terminals, IC bases, lighting equipment, FPCB (flexible printed circuit board), liquid conveying equipment, airplane internal parts, medical equipment, household appliances and the like.

"PS" is polystyrene and refers to a polymer synthesized from styrene monomer by free radical addition polymerization. It is a colorless and transparent thermoplastic plastic with a glass transition temperature higher than 100 ℃, and is often used for manufacturing various disposable containers and disposable foam lunch boxes and the like which need to bear the temperature of boiled water.

The PP is polypropylene, is thermoplastic synthetic resin with excellent performance, and is colorless translucent thermoplastic light general-purpose plastic. Has chemical resistance, heat resistance, electric insulation, high-strength mechanical property, good high-wear-resistance processing property and the like.

"fluorine-containing resin" is a thermoplastic resin containing fluorine atoms in its molecular structure. Has the characteristics of excellent high and low temperature resistance, dielectric property, chemical stability, weather resistance, incombustibility, non-adhesiveness, low friction coefficient and the like.

The PVDF is polyvinylidene fluoride, mainly refers to vinylidene fluoride homopolymer or a copolymer of vinylidene fluoride and other small amount of fluorine-containing vinyl monomers, has the characteristics of both fluorine-containing resin and general resin, and has special performances such as piezoelectric property, dielectric property, hot spot property and the like besides good chemical corrosion resistance, high temperature resistance, oxidation resistance, weather resistance and ray radiation resistance.

"PA" is a polyamide resin, a polycondensation type high molecular compound having a-CONH structure in the molecule, and is usually obtained by polycondensation of a dibasic acid and a diamine. The most prominent advantage of polyamide resins is the extremely narrow range of softening points, unlike other thermoplastic resins, which have a gradual curing or softening process, which causes rapid curing at temperatures slightly below the melting point.

"PE" is polyethylene, a thermoplastic resin obtained by the polymerization of ethylene. In industry, copolymers of ethylene with small amounts of alpha-olefins are also included. The polyethylene is odorless, nontoxic, has wax-like hand feeling, has excellent low-temperature resistance (the lowest use temperature can reach-100 ℃ to-70 ℃), has good chemical stability, and can resist corrosion of most of acid and alkali (cannot resist acid with oxidation property).

PET is polyethylene terephthalate, also commonly known as polyester resin. It is the polycondensate of terephthalic acid and ethylene glycol, belongs to a crystalline saturated polyester, is a milky white or light yellow highly crystalline polymer, and has smooth and glossy surface. Creep resistance, fatigue resistance and friction resistance are good, abrasion is small, hardness is high, and the thermoplastic plastic has the highest toughness; the electric insulation performance is good, and the influence of temperature is small.

"PAN" is an acrylonitrile resin whose main monomer is acrylonitrile, which provides good gas barrier, chemical resistance and gas and odor retention properties. Such resins have moderate tensile strength, good impact resistance when modified or oriented with rubber, and can be processed by extrusion, injection molding, and thermoforming, among other means.

PVA is polyvinyl alcohol, is a water-soluble high-molecular polymer with wide application, and has the performance between that of plastic and rubber.

The PVC is polyvinyl chloride and is a high molecular material obtained by vinyl chloride through addition polymerization reaction.

The PU is polyurethane resin and is a polymer containing urethane groups (-NH-COO-) in the molecular structure.

"SEBS" is a polystyrene-polybutadiene-polystyrene triblock copolymer.

ABS is acrylonitrile-butadiene-styrene copolymer, and is a thermoplastic high polymer material with high strength, good toughness and easy processing and molding.

"PVDF" is polyvinylidene fluoride, a highly non-reactive thermoplastic fluoropolymer.

"PEG" is polyethylene glycol, also known as polyethylene oxide, and refers to a polymer of ethylene oxide.

PTT is polytrimethylene terephthalate which has the characteristics of terylene and chinlon.

"chalcogenide glass" is glass containing sulfide, selenide, antimonide as main components, and also includes chalcogenide compound glass containing oxide, and chalcogenide glass has high processing efficiency and can be precision press-molded.

DMAC is dimethyl acetamide, is an aprotic high-polarity solvent, has a slight ammonia smell and strong dissolving power, can be freely mixed and dissolved with water, aromatic compounds, esters, ketones, alcohols, ethers, benzene, trichloromethane and the like, can activate compound molecules, and is widely used as a solvent and a catalyst.

DMF is dimethylformamide, a colorless transparent liquid, can be mutually soluble with water and most organic solvents, and is a common solvent for chemical reaction.

"magnetic particle diameter", when the magnetic particle is a sphere, the magnetic particle diameter is the diameter of the sphere; when the magnetic particle is an aspherical body, the diameter of the magnetic particle is calculated when the volume of the aspherical body is equal to the volume of the spherical body.

"fiber diameter," which is the diameter of a circle when the fiber is of circular cross-section; when the fiber has a non-circular cross-section, the diameter calculated when the fiber diameter is such that the non-circular cross-sectional area equals the circular cross-sectional area.

The application provides a preparation method of micro-nano magnetic fibers, which is characterized in that the micro-nano magnetic fibers comprise a core layer, and the preparation method comprises the following steps:

In one embodiment, in the method of the present application, in the compounding step, the magnetic particles are compounded with the base material to obtain a plurality of magnetic composite materials, the base material for preparing each magnetic composite material may be different, and the doping concentration of the magnetic particles (the mass percentage of the magnetic particles in the magnetic composite material) may be different or the same between every two magnetic composite materials; in the processing step, the plurality of magnetic composite materials are used for directly preparing the magnetic structured prefabricated rod, or the plurality of magnetic composite materials are used for respectively preparing a plurality of prefabricated rods, and then the plurality of prefabricated rods are used for preparing the structured prefabricated rod.

In the above embodiments, the mass percentage of the magnetic particles in each of the magnetic composites in the method of the present application, the magnetic composites, may be different or the same in the range of 0.01 wt.% to 75 wt.%, for example, may be 0.01 wt.%, 0.1 wt.%, 1 wt.%, 5 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 51 wt.%, 52 wt.%, 53 wt.%, 54 wt.%, 55 wt.%, 56 wt.%, 57 wt.%, 58 wt.%, 59 wt.%, 60 wt.%, 61 wt.%, 62 wt.%, 63 wt.%, 64 wt.%, 65 wt.%, 66 wt.%, 67 wt.%, 68 wt.%, 69 wt.%, 70 wt.%, 71 wt.%, 72 wt.%, 73 wt.%, 74 wt.%, 75 wt.%, etc.

In one embodiment, in the method of the present application, in the compounding step, the magnetic particles and the substrate are uniformly compounded by using a chemical method or a physical method or a combination of the chemical method and the physical method to obtain the magnetic composite particles, the magnetic composite film or the magnetic composite powder.

In one embodiment, the chemical process of the present application comprises the steps of:

(1) chemically dissolving the substrate using a solvent;

(2) doping the magnetic particles into the substrate;

(3) and ultrasonically stirring and dispersing the base material doped with the magnetic particles to obtain a colloidal solution.

In a preferred embodiment of the above embodiment, after obtaining the colloidal solution, the chemical process further comprises: and (4) drying in vacuum to obtain the magnetic composite material.

In a specific embodiment, the solvent may be selected from any one or more of, but not limited to, acetone, methyl ethyl ketone, N-methyl pyrrolidone, Dimethylacetamide (DMAC), Dimethylformamide (DMF), chloroform, cyclohexane, toluene, ethylbenzene, cumene, xylene, bromobenzene, chlorobenzene, dichloromethane, dichloroethane, tetrachloroethane, tetrachloroethylene, styrene, limonene solvent, ethyl acetate, butyl acetate.

In one embodiment, the method of the present application, the physical method comprises the steps of:

(1) physically thermofusing the polymer, i.e., processing the polymer above the glass transition temperature, thereby effectively mixing the polymers at the molecular level;

(2) doping said magnetic particles into said hot molten polymer to form a mixture;

(3) the mixture is extruded at a pressure, speed and shape to form a magnetic composite.

In one embodiment, the obtained magnetic composite material can be uniformly spread to form a film, namely the magnetic composite material film, and the film-state composite material can be directly used for processing a magnetic structured preform. In a preferred embodiment, in order to ensure the doping uniformity of the magnetic particles in the magnetic structured preform, the magnetic composite material thin film can be mechanically broken into particles or powder by a crusher, so as to obtain the magnetic composite material particles or magnetic composite material powder, respectively, which is then used for processing the magnetic structured preform.

In a preferred embodiment, the magnetic composite thin film is obtained using the chemical method. The chemical method results in more uniform doping of the magnetic particles than the physical method.

In one embodiment, the magnetic particles are uniformly compounded with the substrate by a combination of chemical and physical methods, and the magnetic particles are more uniformly doped than by physical methods. The method combining the chemical method and the physical method comprises the following steps:

(1) chemically dissolving the substrate using a solvent;

(2) doping the magnetic particles into the substrate;

(4) And drying the colloidal solution in vacuum to obtain a solid material.

(5) The solid material is heated to a temperature above the glass transition temperature and extruded at a certain pressure, speed and shape to form the magnetic composite material.

In one embodiment, the polymer is selected from, and is not limited to, one or two or more of the following: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether; the glass is selected from and not limited to one or more than two of the following: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

In one embodiment, the magnetic particles are selected from one or more of the following: metal magnetic particles, metal compound magnetic particles, metal alloy magnetic particles; preferably, the metal magnetic particles may be selected from, but not limited to, ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles; the metal compound magnetic particles may be selected from, but are not limited to, metal oxide magnetic particles; the metal oxide magnetic particles may be selected from, but are not limited to, Fe₃O₄Magnetic particles, gamma-Fe₂O₃Magnetic particles; the metal alloy magnetic particles may be selected from, but are not limited to, nickel-cobalt alloy magnetic particles, iron-cobalt alloy magnetic particles, neodymium-iron-boron alloy (NdFeB) magnetic particles, samarium-cobalt alloy (SmCo) magnetic particles.

In a preferred embodiment, in the method of the present application, the magnetic particles may be selected from one or two or more of: ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles, Fe₃O₄Magnetic particles, gamma-Fe₂O₃Magnetic particles, neodymium iron boron alloy magnetic particles, samarium cobalt alloy magnetic particles, nickel cobalt alloy magnetic particles, and iron cobalt alloy magnetic particles.

In one embodiment, the magnetic particles have a diameter of 0.005 to 250. mu.m, and may be, for example, 0.005. mu.m, 0.01. mu.m, 0.05. mu.m, 0.1. mu.m, 0.5. mu.m, 1. mu.m, 5. mu.m, 10. mu.m, 15. mu.m, 20. mu.m, 25. mu.m, 30. mu.m, 35. mu.m, 40. mu.m, 45. mu.m, 50. mu.m, 55. mu.m, 60. mu.m, 65. mu.m, 70. mu.m, 75. mu.m, 80. mu.m, 85. mu.m, 90. mu.m, 95. mu.m, 100. mu.m, 110. mu.m, 120. mu.m, 130. mu.m, 140. mu.m, 150. mu.m, 160. mu.m, 170. mu.m, 180. mu.m, 190. mu.m, 200. mu.m.

In a specific embodiment, the method of the present application, the micro-nano magnetic fiber comprises a core layer, and in the processing step, the magnetic composite material is used to prepare the magnetic structured preform, wherein the magnetic composite material may be one or more, the base materials of the plurality of magnetic composite materials may be different or the same, and the mass percentage content of the contained magnetic particles may be different or the same between two of the plurality of magnetic composite materials. The magnetic composite material finally forms a core layer in the micro-nano magnetic fiber.

In a specific embodiment, the method of the present application, the micro-nano magnetic fiber comprises a core layer and a cladding layer, and in the processing step, the magnetic structured preform is prepared from the magnetic composite material and the cladding layer, wherein the magnetic composite material may be one or more, the base materials of the plurality of magnetic composite materials may be different or the same, and the mass percentage content of the contained magnetic particles may be different or the same between two of the plurality of magnetic composite materials. The magnetic composite material is used for forming a core layer in the micro-nano magnetic fiber, and the material of the cladding is used for forming the cladding in the micro-nano magnetic fiber. The coefficient of thermal expansion of the material of the cladding matches the coefficient of thermal expansion of the magnetic composite material; alternatively, the glass transition temperature or melting point of the material of the cladding is lower than the glass transition temperature or melting point, respectively, of the magnetic composite material. Specifically, the cladding comprises a base material, and the base material is selected from one or more of the following materials: polymers, inorganic glass materials and composites thereof; the polymer may be selected from, but is not limited to, one or two or more of the following: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether; the glass can be selected from but not limited to one or more than two of the following: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

In one embodiment, the cladding comprises magnetic particles and a substrate, and the magnetic particles are composited with the substrate to obtain the material of the cladding. The compounding method is the same as that for preparing the magnetic composite material.

In a specific embodiment, the coating comprises only the substrate and no magnetic particles.

In this application, when the magnetic micro-nanofiber has a cladding, the cladding is a layer on which magnetic particles are dispersed or does not contain the magnetic particles. The core layer is one or more layers which are wrapped by the cladding layer and contain magnetic particles.

In a specific implementation mode, the method of this application, micro-nano magnetic fiber includes sandwich layer and high melting point functional layer, in the hot drawing step, the cladding of magnetism structural preform the material of high melting point functional layer, and with the material machinery of high melting point functional layer adopts hot drawing technology preparation in step micro-nano magnetic fiber realizes that hot drawing makes the cladding of micro-nano magnetic fiber in-process to high melting point functional layer material. The glass transition temperature and the melting point of the material of the high-melting-point functional layer are respectively higher than those of the magnetic composite material, and the material of the high-melting-point functional layer is a fibrous material or a material capable of being processed into a fibrous state, such as a quartz optical fiber, a metal electrode, a semiconductor material, and the like. The material of the high-melting-point functional layer is used for forming the high-melting-point functional layer.

In a specific embodiment, in the method of the present application, the micro-nano magnetic fiber includes a core layer, a cladding layer and a high-melting-point functional layer, and in the processing step, the magnetic structured preform is prepared by using the magnetic composite material and the material of the cladding layer, wherein the magnetic composite material may be one or more, the base materials of the plurality of magnetic composite materials may be different or the same, and the mass percentage content of the magnetic particles contained in the plurality of magnetic composite materials may be different or the same between two magnetic composite materials; in the hot drawing step, the magnetic structural prefabricated rod wraps the material of the high-melting-point functional layer, and the micro-nano magnetic fiber is prepared by adopting a hot drawing process in mechanical synchronization with the material of the high-melting-point functional layer. The magnetic composite material is used for forming a core layer in the micro-nano magnetic fiber, and the material of the cladding is used for forming the cladding in the micro-nano magnetic fiber; the material of the high-melting-point functional layer is used for forming the high-melting-point functional layer.

In one embodiment, the method of the present application, wherein the processing step, the magnetically structured preform is prepared using one or more of a film winding method, a thermal pressing method, an extrusion molding method, and a 3D printing method; further, the method can also comprise one or more than two methods as follows: machining, assembling and thermosetting.

In a specific embodiment, in the method of the present application, the magnetic composite material is one or more than two magnetic composite material thin films, and the magnetic structured preform is processed by a thin film winding method, first, one magnetic composite material thin film is subjected to hot pressing and mechanical processing to obtain a columnar original preform, then, other magnetic composite material thin films are sequentially wound on the original preform, the other magnetic composite material thin films respectively form a preform, and then, each preform is subjected to thermosetting treatment to obtain a final magnetic structured preform. The Young's modulus of each of the magnetic composite material thin films is 0.01 to 1GPa, and may be, for example, 0.01GPa, 0.02GPa, 0.03GPa, 0.04GPa, 0.05GPa, 0.06GPa, 0.07GPa, 0.08GPa, 0.09GPa, 0.1GPa, 0.15GPa, 0.2GPa, 0.25GPa, 0.3GPa, 0.35GPa, 0.4GPa, 0.45GPa, 0.5GPa, 0.55GPa, 0.6GPa, 0.65GPa, 0.75GPa, 0.8GPa, 0.85GPa, 0.9GPa, 0.95GPa, or 1 GPa.

The hot pressing method is a method of molding and sintering a material such as a magnetic composite material into a preform under heating and simultaneously pressurizing conditions. In one embodiment, the method of the present application utilizes a hot pressing process to process a magnetically structured preform. According to the arrangement of the hot pressing mold, the magnetic composite material can be pressed into various shapes, one prefabricated rod is pressed each time, and the magnetic structural prefabricated rod can be prepared for different prefabricated rods by utilizing a mechanical processing method and an assembly method. Specifically, the mechanical processing method can cut the rectangular preform into a cylindrical or annular preform. More specifically, the cylindrical preform and the annular preform can be used for preparing the magnetic structured preform by an assembly method. Alternatively, the preform rod of different shape cut by the mechanical processing may be used in other methods such as a film winding method, an extrusion molding method, and a 3D printing method. Wherein the hot pressing temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material, the hot pressing temperature is 25-600 ℃, preferably 120-250 ℃, and can be, for example, 25 ℃, 35 ℃, 45 ℃, 55 ℃, 65 ℃, 75 ℃, 85 ℃, 95 ℃, 105 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, 145 ℃, 150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃, 195 ℃, 200 ℃, 205 ℃, 210 ℃, 215 ℃, 220 ℃, 225 ℃, 230 ℃, 235 ℃, 240 ℃, 245 ℃ and 250 ℃; the hot pressing time is 5-600 min, preferably 10-20 min, for example, 5min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min, 25min, 30min, 35min, 50min, 60min, 70min, 80min, 90min, 100min, 120min, 140min, 180min, 22min, 260min, 300min, 340min, 380min, 420min, 460min, 500 min.

"extrusion molding" is a method of preparing a preform by placing a material in a mold and then molding it through a hole mold by strong extrusion. In one embodiment, the method of the present application utilizes an extrusion process to process a magnetically structured preform. Optionally, in the present application, a plurality of magnetic composite materials may be placed in one mold, and a magnetic structured preform containing a plurality of magnetic composite materials may be directly extruded; the magnetic composite material can be put into a mould respectively to be extruded into different prefabricated rods, and then the prefabricated rods are used for preparing the final magnetic structural prefabricated rod by one or two or three of an assembling method, a thermosetting method and a mechanical processing method. Wherein the extrusion temperature is not lower than the glass transition temperature or the melting point of the magnetic composite material, the extrusion temperature is 50-700 ℃, preferably 200-400 ℃, and can be, for example, 50 ℃, 70 ℃, 90 ℃, 110 ℃, 130 ℃, 150 ℃, 170 ℃, 190 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 500 ℃, 600 ℃ and 700 ℃.

The "3D printing method" is a method of rapidly constructing an object by layer-by-layer printing using an adhesive material based on a digital model file. In one embodiment, the method of the present application, the magnetically structured preform is directly processed using a 3D printing method. In another embodiment, after the preform is processed by 3D printing, other methods such as film winding, thermal compaction, extrusion may be used to produce the final magnetically structured preform.

In a specific embodiment, the micro-nano magnetic fiber includes a core layer, the micro-nano magnetic fiber obtained in the hot drawing step can be used as a fibrous structured magnetic composite material, and a 3D printing method is used for performing secondary processing and secondary hot drawing, specifically, the method includes the following steps:

processing: preparing the magnetic structured prefabricated rod by one or more than two methods of a film winding method, a hot pressing method, an extrusion forming method and a 3D printing method;

hot drawing: preparing micro-nano magnetic fibers from the magnetic structured preform by adopting a hot drawing process;

secondary processing: preparing a second magnetic structured preform by using the micro-nano magnetic fiber through the 3D printing method;

secondary hot drawing: and preparing the second magnetic structured preform rod into the second micro-nano magnetic fiber by adopting a hot drawing process.

In an optional implementation manner of the above specific implementation manner, the micro-nano magnetic fiber two includes a cladding two, and in the secondary processing step, the magnetic structured preform two is prepared by using materials of the micro-nano magnetic fiber and the cladding two through a 3D printing method;

in an optional implementation manner of the foregoing specific embodiment, the micro-nano magnetic fiber two includes a second high-melting-point functional layer, and the second magnetic structured preform coats the material of the second high-melting-point functional layer, and the micro-nano magnetic fiber two and the material of the second high-melting-point functional layer are mechanically and synchronously prepared by a hot drawing process.

In a specific embodiment, the printing temperature of the 3D printing method for preparing the magnetic structured preform in the processing step and the printing temperature of the 3D printing method for preparing the magnetic structured preform in the secondary processing step are not lower than the glass transition temperature or the melting point of the magnetic composite material; the printing temperature is 50-700 deg.C, preferably 200-400 deg.C, such as 50 deg.C, 70 deg.C, 90 deg.C, 110 deg.C, 130 deg.C, 150 deg.C, 170 deg.C, 190 deg.C, 200 deg.C, 210 deg.C, 220 deg.C, 230 deg.C, 240 deg.C, 250 deg.C, 260 deg.C, 270 deg.C, 280 deg.C, 290 deg.C, 300 deg.C, 310 deg.C, 320 deg.C, 330 deg.C.

The "thermosetting method" is a method of curing the binder system by changing the energy of the molecules, and in this application means that the final magnetic structured preform is prepared by heating and curing between different preforms. In one embodiment, in the method of the present application, in the processing step, the curing temperature of the thermal curing method is not lower than the glass transition temperature or the melting point of the magnetic composite material; the curing temperature is 50-500 ℃, preferably 150-300 ℃, for example 50 ℃, 70 ℃, 90 ℃, 110 ℃, 130 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 450 ℃ and 500 ℃; the curing time is 1-500 min, preferably 20-40 min, and can be, for example, 1min, 5min, 10min, 15min, 20min, 22min, 24min, 26min, 28min, 30min, 32min, 34min, 36min, 38min, 40min, 100min, 130min, 160min, 190min, 220min, 250min, 280min, 310min, 340min, 370min, 400min, 430min, 460min, 490min, 500 min.

In one embodiment, the substrate, the magnetic composite material and the micro-nano magnetic fiber are dried in vacuum before use; the vacuum drying temperature is 20-300 deg.C, preferably 60-150 deg.C, such as 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C, 90 deg.C, 100 deg.C, 110 deg.C, 120 deg.C, 130 deg.C, 140 deg.C, 150 deg.C, 160 deg.C, 170 deg.C, 180 deg.C, 190 deg.C, 200 deg.C, 210 deg.C, 220 deg.C, 230; the vacuum drying time is 2-2000 h, preferably 12-50 h, and can be, for example, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h, 50h, 60h, 80h, 100h, 300h, 500h, 700h, 1000h, 1200h, 1400h, 4600h, 1800h, 2000h, and the like.

In one embodiment, the method of the present application, the temperature of the hot drawing process is 25 to 600 ℃, preferably 230 to 400 ℃, and may be, for example, 25 ℃, 50 ℃, 75 ℃, 100 ℃, 125 ℃, 150 ℃, 175 ℃, 200 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃; the tension of the hot drawing process is 0-500 g, preferably 10-50 g, for example, 0g, 2g, 4g, 6g, 8g, 10g, 12g, 14g, 16g, 18g, 20g, 22g, 24g, 26g, 28g, 30g, 32g, 34g, 36g, 38g, 40g, 42g, 44g, 46g, 48g, 50g, 100g, 150g, 200g, 250g, 300g, 350g, 400g, 450g, 500 g; the drawing speed of the thermal drawing process is 0.1m/min to 5000m/min, and may be, for example, 0.1m/min, 1m/min, 10m/min, 100m/min, 300m/min, 500m/min, 700m/min, 900m/min, 1000m/min, 2000m/min, 3000m/min, 4000m/min, or 5000 m/min.

Fig. 1 is a schematic view of an apparatus for preparing micro-nano magnetic fibers by using a thermal drawing process according to an embodiment of the present application. The prefabricated excellent anchor clamps 2 are responsible for holding fixed prefabricated stick 1 and send the stick, and fiber drawing tower heating furnace 3 is responsible for local heating prefabricated stick 1 to make it soften, treat the prefabricated stick lower end after falling, the draw gear 5 of closed fiber drawing tower realizes prefabricated stick 1 hot wire drawing preparation micro-nano magnetic fiber. The diameter of the fiber can be controlled by controlling the rod feeding speed of the clamp and the traction speed of the traction device. The fiber diameter is observed in real time by the fiber laser caliper 4. The collection of the fibres is achieved by means of a fibre collection device 6 of the drawing tower.

In a specific embodiment, in the method of the present application, the structure of the micro-nano magnetic fiber is determined by the structure of the magnetic structured preform. The structures of the magnetic structured prefabricated rod and the micro-nano magnetic fiber are not limited, and the structures of the magnetic structured prefabricated rod and the micro-nano magnetic fiber are consistent along the axial direction of the fiber. The structure can be any axial invariant structure, more specifically, according to the distribution of the magnetic particle concentration, the structure can be a single-concentration magnetic particle doping structure or a multi-concentration magnetic particle doping structure; according to the existence of the cladding, the structure can be divided into a cladding structure and a non-cladding structure; the structure may also be a structure containing a high melting point functional layer, and the like. As shown in fig. 2A to 2C, the cross-sectional views of the micro-nano magnetic fiber doped with magnetic particles of a single concentration are different in shape. As shown in fig. 3A to 3C, the cross-sectional views of the micro-nano magnetic fiber with a multi-concentration magnetic particle doping structure are different shapes, specifically, the cross-sectional views of the micro-nano magnetic fiber with a multi-layer core structure (also referred to as a "radial concentration distribution doping structure") are different shapes. As shown in fig. 4A to 4F, schematic cross-sectional views of different shapes of the micro-nano magnetic fiber with a multi-concentration magnetic particle doped structure, specifically, schematic cross-sectional views of different shapes of the micro-nano magnetic fiber with a plurality of non-discrete strip-structured core layers. As shown in fig. 5, the schematic diagram of the circular cross section of the micro-nano magnetic fiber containing the high melting point functional layer structure is shown, specifically, the schematic diagram of the circular cross section of the micro-nano magnetic fiber containing the integrated quartz optical fiber (white) and the integrated metal electrode (black). As shown in fig. 6, the schematic diagram of the circular cross section of the micro-nano magnetic fiber with a multi-concentration magnetic particle doped structure is shown, specifically, the schematic diagram of the circular cross section of the micro-nano magnetic fiber with two discrete core layers in a strip structure and including a cladding layer is shown.

In a specific embodiment, the color depth in fig. 2A to fig. 6 can be used to distinguish the cladding layer, the core layer, and the high melting point functional layer of the micro-nano magnetic fiber, or can represent the doping concentration of the magnetic particles, and the color depth is higher, lower, or the same as the color depth.

The application also provides the micro-nano magnetic fiber prepared by any one of the methods.

In addition, the application also provides a micro-nano magnetic fiber, which is characterized by comprising a core layer, wherein the core layer comprises magnetic particles and a base material, and the magnetic particles are distributed in the base material;

In one embodiment, the micro-nano magnetic fiber of the present application, the metal magnetic particles may be selected from, but not limited to, gold magnetic particles, silver magnetic particles, ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles; the metal compound magnetic particles may be selected from, but are not limited to, metal oxide magnetic particles; the metal oxide magnetic particles may be selected from, but are not limited to, Fe₃O₄Magnetic particles, gamma-Fe₂O₃Magnetic particles; the metal alloy magnetic particles may be selected from, but are not limited to, nickel-cobalt alloy magnetic particles, iron-cobalt alloy magnetic particles, neodymium-iron-boron alloy (NdFeB) magnetic particles, samarium-cobalt alloy (SmCo) magnetic particles.

In a preferred embodiment, the magnetic particles of the micro-nano magnetic fiber of the present application may be selected from one or more of the following: ferromagnetic particles, cobalt magnetic particles, nickel magnetic particles, Fe₃O₄Magnetic particles, gamma-Fe₂O₃Magnetic particles, neodymium iron boron alloy magnetic particles, samarium cobalt alloy magnetic particles, nickel cobalt alloy magnetic particles, and iron cobalt alloy magnetic particles.

In a specific embodiment, the micro-nano magnetic fiber of the present application, the polymer is selected from and not limited to one or more of the following: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether; the glass is selected from and not limited to one or more than two of the following: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

In one embodiment, the magnetic particles of the magnetic nanofiber have a diameter of 0.005-250 μm, such as 0.005 μm, 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, etc.

In one embodiment, the micro-nano magnetic fiber of the present application has a diameter of 0.01 to 3000 μm, preferably 50 to 1000 μm, for example, 0.01 μm, 1 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, 1500 μm, 1600 μm, 1700 μm, 1800 μm, 1900 μm, 2000 μm.

In a specific embodiment, the micro-nano magnetic fiber of this application, micro-nano magnetic fiber is the columnar structure, micro-nano magnetic fiber cross section shape does not have the restriction, can select from following one or more than two kinds: circular, triangular, rectangular, polygonal, irregular.

In one embodiment, the micro-nano magnetic fiber of the present application may be any axially invariant structure, such as a single-concentration magnetic particle doped structure, a multi-concentration magnetic particle doped structure, a cladding-containing structure, a cladding-free structure, a high-melting-point functional layer-containing structure, and the like. Wherein, the single concentration of the magnetic particles is doped, which means that only one concentration of the magnetic particles is uniformly distributed in the core layer. The 'multi-concentration magnetic particle doping' means that the mass percentage of the magnetic particles in various magnetic composite materials are not completely the same, so that the magnetic particles are doped in multiple concentrations in the micro-nano magnetic fiber.

In a specific embodiment, the micro-nano magnetic fiber of the present application, the core layer is a multilayer structure from inside to outside, in any one layer of the core layer, the magnetic particles are in the in-layer uniform distribution. The mass percentage of the magnetic particles in each of the layers of the core layer is 0.01 wt.% to 75 wt.%, preferably 1 wt.% to 75 wt.%, and may be, for example, 0.01 wt.%, 0.1 wt.%, 1 wt.%, 5 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 51 wt.%, 52 wt.%, 53 wt.%, 54 wt.%, 55 wt.%, 56 wt.%, 57 wt.%, 58 wt.%, 59 wt.%, 60 wt.%, 61 wt.%, 62 wt.%, 63 wt.%, 64 wt.%, 65 wt.%, 66 wt.%, 67 wt.%, 68 wt.%, 69 wt.%, 70 wt.%, 71 wt.%, 72 wt.%, 73 wt.%, 74 wt.%, 75 wt.%, etc.

In a specific embodiment, in the micro-nano magnetic fiber of the present application, compared with each layer in the multiple layers of the core layer, the mass percentage of the magnetic particles in two, three, four, five, or six layers may be different.

In a specific embodiment, the mass percentage of the magnetic particles in each of the plurality of layers of the core layer is gradually decreased from the inside to the outside as compared to each of the plurality of layers.

In a specific embodiment, the mass percentage of the magnetic particles in each of the plurality of layers of the core layer is gradually increased from the inside to the outside as compared to each of the plurality of layers.

In a specific embodiment, the micro-nano magnetic fiber of the present application, the cross section of the core layer is circular, rectangular, triangular or irregular, the cross section is divided into two, three, four, five, six, seven, eight, nine or ten or more regions, thereby the core layer is divided into two, three, four, five, six, seven, eight, nine or ten or more strip structures, in any one strip structure, the magnetic particles are in uniform distribution in the strip structure, and the mass percentage content of the magnetic particles in at least two strip structures is different.

In a specific embodiment, in the micro-nano magnetic fiber of the present application, the cross section of the core layer is circular, and the cross section is divided into two, three, four, five, six, or more than seven sector regions; preferably, the cross section is divided into two equal semicircular areas, so that the core layer is divided into two strip-shaped structures, the magnetic particles are uniformly distributed in each strip-shaped structure, and the mass percentages of the magnetic particles in the two strip-shaped structures are different.

In a specific embodiment, the micro-nano magnetic fiber of the present application, the cross section of the core layer is rectangular, and the cross section is divided into any two, three, four or five equal rectangular areas.

In a specific embodiment, the cross section of the core layer of the micro-nano magnetic fiber is triangular, and the cross section is divided into any two triangular areas. In a preferred embodiment, the triangle is an isosceles triangle, and the cross section is divided into any two equal triangular areas.

In a specific embodiment, the micro-nano magnetic fiber of the present application includes a core layer and a high-melting-point functional layer, wherein the core layer wraps the high-melting-point functional layer; the glass transition temperature and the melting point of the material of the high-melting-point functional layer are respectively higher than those of the material of the core layer, and the material of the high-melting-point functional layer is a fibrous material or a material capable of being processed into a fibrous state, for example, a quartz optical fiber or a metal semiconductor can be used.

In a specific embodiment, the micro-nano magnetic fiber of the present application includes a core layer and a cladding layer, where the material of the cladding layer and the material of the core layer can be hot-drawn together, and the cladding layer wraps the core layer; the thermal expansion coefficient of the material of the cladding layer is the same as that of the material of the core layer; alternatively, the glass transition temperature and the melting point of the material of the cladding layer are lower than the glass transition temperature and the melting point of the material of the core layer, respectively.

In a specific embodiment, the micro-nano magnetic fiber of the present application includes a core layer, a cladding layer, and a high melting point functional layer, wherein the core layer wraps the high melting point functional layer, and the cladding layer wraps the core layer; co-thermal drawable of the material of the cladding layer and the material of the core layer; the thermal expansion coefficient of the material of the cladding layer is the same as that of the material of the core layer; alternatively, the glass transition temperature and the melting point of the material of the cladding layer are lower than the glass transition temperature and the melting point of the material of the core layer, respectively.

In one embodiment, the material of the cladding of the micro-nano magnetic fiber of the present application may be selected from one or more of the following polymers: polymethyl methacrylate (PMMA), PMMA composite material doped with fluorinated polymer (F-PMMA), styrene methyl dimethacrylate copolymer (SMMA), Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), Polycarbonate (PC), polyphenylene sulfone resin (PPSU), polyether sulfone resin (PES), Polyethyleneimine (PEI), Polystyrene (PS), Polyamide (PA) and polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), Polyurethane (PU), styrene-ethylene/butylene-styrene block copolymer (SEBS), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polytrimethylene terephthalate (PTT), and polyether; the cladding material may also be selected from one or more than two of the following glasses: chalcogenide glasses, germanate glasses, tellurate glasses, metal oxide glasses, silicate glasses, germanosilicate glasses, and fluoride glasses.

In one embodiment, the micro-nano magnetic fiber of the present application includes a core layer and a cladding layer, wherein the cladding layer wraps the core layer; the core layer comprises two, three, four, five, six or more than seven discrete strip-shaped structures, and the two, three, four, five, six or more than seven strip-shaped structures are mutually discrete, namely, two strip-shaped structures are not contacted with each other.

In the above specific embodiment, the cross section of the micro-nano magnetic fiber may be circular, triangular, rectangular, or irregular.

In a specific embodiment, in the micro-nano magnetic fiber of the present application, the mass percentages of the magnetic particles in the discrete strip-shaped structures are not completely the same.

In a specific embodiment, in the micro-nano magnetic fiber of the present application, the mass percentage of the magnetic particles in any one stripe structure of the core material is 0.01 wt.% to 75 wt.%, preferably 1 wt.% to 75 wt.%, and may be, for example, 0.1 wt.%, 1 wt.%, 5 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 51 wt.%, 52 wt.%, 53 wt.%, 54 wt.%, 55 wt.%, 56 wt.%, 57 wt.%, 58 wt.%, 59 wt.%, 60 wt.%, 61 wt.%, 62 wt.%, 63 wt.%, 64 wt.%, 65 wt.%, 66 wt.%, 67 wt.%, 68 wt.%, 69 wt.%, 70 wt.%, 71 wt.%, 72 wt.%, 73 wt.%, 74 wt.%, 75 wt.%, and the like.

Examples

Example 1

The application provides a micro-nano magnetic fiber with a single-concentration magnetic particle doping structure, as shown in figures 2A-2C.

The preparation method of the micro-nano magnetic fiber of the embodiment, wherein the polymer is Cyclic Olefin Copolymer (COC), and the magnetic particles are NdFeB micron particles, specifically comprises the following steps:

(1) preparation of magnetic composite materials

Taking 14g of dried cycloolefin copolymer (COC) particles, dissolving in a chloroform solvent, adding 6g of NdFeB micron particles, stirring and ultrasonically processing to obtain a uniformly mixed colloidal solution. Drying the mixture at a high specific surface area at normal temperature, and performing vacuum drying to obtain the magnetic composite material with the NdFeB doping concentration of 30 wt.%. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

And (3) performing hot pressing and mechanical cold processing on the magnetic composite polymer with the NdFeB doping concentration of 30 wt.% obtained in the step (1) to obtain a magnetic structured preform with the NdFeB doping concentration of 30 wt.%, wherein the magnetic structured preform is circular. The hot pressing temperature is 160 ℃, and the hot pressing time is 20 min.

(3) Preparation of micro-nano magnetic fiber

A hot drawing apparatus as shown in fig. 1 was used. And (3) performing hot wire drawing on the magnetic structured preform with the NdFeB doping concentration of 30 wt.% obtained in the step (2) to obtain micro-nano magnetic fibers with the NdFeB doping concentration of 30 wt.%, wherein the cross section of each fiber is circular, as shown in fig. 2A. The hot wire drawing temperature is 240 ℃, the traction speed is 1m/min, and the diameter of the prepared micro-nano magnetic fiber is 300 mu m.

Example 2

The application provides a micro-nano magnetic fiber of a structure doped with single-concentration magnetic particles, wherein a polymer is a Cyclic Olefin Copolymer (COC), and the magnetic particles are NdFeB micron particles.

The preparation method of the micro-nano magnetic fiber of the embodiment specifically comprises the following steps:

(1) preparation of magnetic composite materials

Taking 20g of dried cycloolefin copolymer (COC) particles, dissolving in a chloroform solvent, adding 30g of NdFeB micron particles, and stirring and ultrasonically processing to obtain a uniform colloidal solution. Drying the mixture at a high specific surface area at normal temperature, and performing vacuum drying to obtain the magnetic composite material with the NdFeB doping concentration of 60 wt.%. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

And (3) performing hot pressing and mechanical cold processing on the magnetic composite polymer with the NdFeB doping concentration of 60 wt.% obtained in the step (1) to obtain a magnetic structured preform with the NdFeB doping concentration of 60 wt.%. The hot pressing temperature is 140 ℃ and the hot pressing time is 20 min.

(3) Preparation of micro-nano magnetic fiber

And (3) carrying out hot drawing on the magnetic structural preform with the NdFeB doping concentration of 60 wt.% obtained in the step (2) to obtain micro-nano magnetic fibers with the NdFeB doping concentration of 60 wt.%, wherein the cross section of each fiber is circular. The hot wire drawing temperature is 220 ℃, the traction speed is 1m/min, and the diameter of the prepared micro-nano magnetic fiber is 300 mu m. When the hot wire drawing temperature is 220 ℃ and the drawing speed is 9m/min, the diameter of the prepared micro-nano magnetic fiber is 100 mu m.

Example 3

The embodiment provides a micro-nano magnetic fiber doped with radial concentration distribution, as shown in fig. 3A to 3C.

The preparation method of the micro-nano magnetic fiber of the embodiment, wherein the polymer is F-PMMA, and the magnetic particles are NdFeB micron particles, specifically comprises the following steps:

(1) preparation of magnetic composite materials

Dried F-PMMA particles of 16g, 5g, 3g and 7.5g are respectively taken and dissolved in an acetone solvent, NdFeB micron particles of 4g, 5g, 7g and 22.5g are respectively added, and stirring and ultrasonic treatment are carried out to obtain 4 parts of uniform colloidal solution. Drying the high specific surface area at normal temperature, and drying in vacuum to obtain the magnetic composite material film with NdFeB doping concentrations of 20 wt.%, 50 wt.%, 70 wt.% and 75 wt.%. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

And (2) performing hot pressing and mechanical cold working on the magnetic composite material film with the NdFeB doping concentration of 75 wt.% obtained in the step (1) to obtain an original preform I with the NdFeB doping concentration of 75 wt.%, sequentially winding the magnetic polymer films with the NdFeB doping concentrations of 70 wt.%, 50 wt.% and 20 wt.% outside the original preform I by using a film winding method, and performing hot curing treatment on the preform after the film winding to obtain a magnetic structural preform I with a radial concentration distribution doping structure. And (2) performing hot pressing and mechanical cold working on the magnetic composite material film with the NdFeB doping concentration of 20 wt.% obtained in the step (1) to obtain an original preform II with the NdFeB doping concentration of 20 wt.%, and sequentially winding the magnetic polymer films with the NdFeB doping concentrations of 50 wt.%, 70 wt.% and 75 wt.% outside the original preform by using a film winding method and performing hot curing treatment to obtain a magnetic structural preform II with a radial concentration distribution doping structure. The cross sections of the first magnetic structural prefabricated rod and the second magnetic structural prefabricated rod can be circular, rectangular or triangular. The hot pressing temperature is 130 ℃ and the hot pressing time is 20 min. The curing temperature is 120 ℃, and the curing time is 30 min.

(3) Preparation of micro-nano magnetic fiber

And (3) carrying out hot wire drawing on the magnetic structural prefabricated rod I and the magnetic structural prefabricated rod II of the radial concentration distribution doping structure obtained in the step (2) to obtain the micro-nano magnetic fiber of the radial concentration distribution doping structure, wherein the cross section of the micro-nano magnetic fiber is circular, rectangular or triangular, as shown in figures 3A-3C. The hot wire drawing temperature is 230 ℃, the drawing speed is 1m/min, and the diameters of the prepared micro-nano magnetic fiber I and the micro-nano magnetic fiber II are both 300 mu m.

The micro-nano magnetic fibers prepared in examples 1 to 3 are compared, and the results are shown in table 1, after the magnetic field of 1T is magnetized, the micro-nano magnetic fibers prepared in example 2 with the magnetic particle doping concentration of 60 wt.% have higher magnetism than that of example 1, which indicates that the magnetic particles with high doping concentration can be introduced into the fibers by the thermal drawing method of the present application, so that high magnetic force response and high residual magnetic field strength of the fibers are achieved. In each bar structure of the core layer of the micro-nano magnetic fiber with the radial concentration distribution doping structure prepared in example 3, the highest doping concentration of the magnetic particles is 75 wt.%, and the magnetic property of the micro-nano magnetic fiber is higher than that of the micro-nano magnetic fiber with the single concentration of the magnetic particles prepared in examples 1 and 2, which indicates that the micro-nano magnetic fiber prepared by the thermal drawing method is beneficial to the improvement of the concentration of the magnetic particles, thereby enhancing the magnetic property. The micro-nano magnetic fiber with the radial concentration distribution doping structure prepared in the embodiment 3 has stronger mechanical strength than the micro-nano magnetic fiber doped with magnetic particles with single concentration while realizing high-concentration doping of the magnetic particles, which shows that the mechanical property of the micro-nano magnetic fiber prepared by the thermal drawing method can be greatly improved, so that the micro-nano magnetic fiber can be widely applied.

In embodiment 3, the first radial concentration distribution doping structure and the second radial concentration distribution doping structure have different magnetic particle doping concentration distributions, wherein the first radial concentration distribution doping structure is a concentration distribution in which the magnetic particle doping concentration decreases from inside to outside, the second radial concentration distribution doping structure is a concentration distribution in which the magnetic particle doping concentration increases from inside to outside, and the fiber surface single-point remanence field of the second radial concentration distribution doping structure is higher than that of the first radial concentration distribution doping structure. Therefore, under the condition of only considering the size of the fiber remanence field, the concentration distribution of the magnetic particles which is gradually increased from inside to outside can increase the size of the remanence field of the micro-nano magnetic fiber.

TABLE 1

Example 4

The application provides a micro-nano magnetic fiber of many concentrations magnetic particle doping structure, and is specific, and this embodiment provides a micro-nano magnetic fiber that has two strip structure's sandwich layer, and include the cladding, as shown in fig. 4A-4C.

In the preparation method of the micro-nano magnetic fiber of the embodiment, the polymer is Cyclic Olefin Copolymer (COC), and the magnetic particles are Fe₃O₄The nanoparticle specifically comprises the following steps:

(1) preparation of magnetic composite materials

30g and 9g of dried cycloolefin copolymer (COC) particles were dissolved in chloroform, and 70g and 1g of Fe were added₃O₄And (3) stirring and ultrasonically treating the micron particles to obtain a uniformly mixed colloidal solution. Drying at normal temperature and vacuum drying with high specific surface area to obtain Fe₃O₄The doping concentration of the magnetic composite material is 70 wt.% and 10 wt.%, respectively. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

And (2) performing hot pressing and mechanical cold processing on the magnetic composite material obtained in the step (1), and then assembling the magnetic composite material with a pure COC material to obtain a magnetic structured preform which contains a cladding and has an asymmetric structure (namely, the doping concentration of magnetic particles is asymmetrically distributed on the cross section of the magnetic structured preform), wherein the magnetic structured preform can be round, rectangular or triangular. The hot pressing temperature is 130 ℃ and the hot pressing time is 20 min.

(3) Preparation of micro-nano magnetic fiber

And (3) carrying out hot wire drawing on the magnetic structure prefabricated rod with the doping concentration asymmetric structure obtained in the step (2) to obtain the micro-nano magnetic fiber with the cladding asymmetric structure (namely, the doping concentration of the magnetic particles is asymmetrically distributed on the cross section of the micro-nano magnetic fiber), and the micro-nano magnetic fiber can be round, rectangular or triangular, as shown in fig. 4A-4C. The hot wire drawing temperature is 240 ℃, the drawing speed is 5m/min, and the diameter of the prepared micro-nano magnetic fiber is 100 mu m.

The micro-nano magnetic fibers prepared in example 2 and example 4 were compared, and the results are shown in table 2 below. Under the condition of the same doping concentration of the magnetic particles, the asymmetric micro-nano magnetic fiber prepared in embodiment 4 can realize non-contact actions such as rotation, twisting and bending under a magnetic field of 50 mT. The asymmetric micro-nano magnetic fiber prepared in embodiment 4 has higher mechanical strength than the micro-nano magnetic fiber with a single-concentration magnetic particle doping structure while realizing high-concentration doping of magnetic particles. Therefore, the structural fiber prepared by the hot drawing method can realize diversification of fiber functions while greatly improving the mechanical property of the structural fiber.

TABLE 2

Example 5

The application provides a micro-nano magnetic fiber of a multi-concentration magnetic particle doping structure, in particular to a micro-nano magnetic fiber with a magnetic particle doping concentration of a two-dimensional code structure or a cross structure on a cross section. As shown in fig. 4E and 4F.

In the preparation method of the micro-nano magnetic fiber of the embodiment, the polymer is Cyclic Olefin Copolymer (COC), and the magnetic particles are SrFe₁₂O₁₉The micron particle specifically comprises the following steps:

(1) preparation of magnetic composite materials

Respectively taking 1g, 3g, 5g, 7g, 8g and 9g of dried cycloolefin copolymer (COC) particles, respectively dissolving in chloroform reagent, respectively adding 9g, 7g, 5g, 3g, 2g and 1g of SrFe₁₂O₁₉And (3) stirring and ultrasonically treating the micron particles to obtain a uniformly mixed colloidal solution. Drying at high specific surface area under normal temperature and vacuum to obtain six different SrFe₁₂O₁₉Magnetic recombination of doping concentrationAnd (3) material powder. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

Six SrFe obtained in the step (1)₁₂O₁₉3D printing of magnetic composite powder doped with SrFe in doping concentration₁₂O₁₉The cross-structured magnetic structured preform. The printing temperature was 260 ℃.

(3) Preparation of micro-nano magnetic fiber

Doping SrFe obtained in the step (2)₁₂O₁₉The special-shaped structure magnetic structure prefabricated rod is subjected to hot wire drawing, and the micro-nano magnetic fiber with the structure shown in figure 4F is obtained. The hot wire drawing temperature is 240 ℃, the traction speed is 0.5m/min, and the diameter of the prepared micro-nano magnetic fiber is 500 mu m.

The micro-nano magnetic fiber obtained by the embodiment has highly customized magnetic microparticle distribution.

Example 6

The embodiment provides a micro-nano magnetic fiber integrated with multiple electrodes and optical fibers, as shown in fig. 5.

(1) preparation of magnetic composite materials

Taking 20g of dried cycloolefin copolymer (COC) particles, dissolving in chloroform reagent, adding 30g of SrFe₁₂O₁₉And (3) stirring and ultrasonically treating the micron particles to obtain a uniformly mixed colloidal solution. High specific surface area, normal temperature drying and vacuum drying to obtain SrFe₁₂O₁₉A magnetic composite material having a doping concentration of 60 wt.%. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

Carrying out hot pressing and mechanical cold processing on the magnetic composite material obtained in the step (1) to obtain SrFe with the outer diameter of 18mm, the diameter of an inner through hole of 2mm and the diameter of a peripheral through hole of 1mm₁₂O₁₉DopingA tubular magnetically structured preform with a concentration of 60 wt.%, in fig. 5 the central white circular portion represents the inner through hole and the black circular portion represents the surrounding through hole. The hot pressing temperature is 130 ℃ and the hot pressing time is 20 min.

(3) Preparing micro-nano magnetic fibers:

and respectively enabling the quartz optical fiber and the metal electrode with proper diameters to pass through the inner through hole and the peripheral through hole of the magnetic structured prefabricated rod, fixing the lower end of the magnetic structured prefabricated rod, and performing hot wire drawing on the magnetic structured prefabricated rod under mechanical synchronization to obtain the micro-nano magnetic fiber integrated with the optical fiber and the multiple electrodes. The hot wire drawing temperature is 230 ℃, the wire feeding speed and the traction speed of the quartz optical fiber and the metal electrode are kept consistent and are 0.5 m/min. The wire feeding speed refers to the speed of uniformly descending the optical fiber and the electrode material through control. The diameter of the prepared micro-nano magnetic fiber is 500 mu m.

The micro-nano magnetic fiber obtained by the embodiment has the functions of flexible magnetic control, light guide and multi-electrode electric signal reading.

Example 7

In this embodiment, a micro-nano magnetic fiber having two core layers of discrete stripe structures and including a cladding layer is provided, as shown in fig. 6. The polymer is a COC polymer and a PMMA polymer, and the magnetic micron particle material is NdFeB micron particles.

(1) Preparation of magnetic polymers

Taking 20g of dried cycloolefin copolymer (COC) particles, dissolving the particles in a chloroform reagent, adding 30g of NdFeB micron particles, and stirring and ultrasonically processing the mixture to obtain a uniformly mixed colloidal solution. And drying the mixture with high specific surface area at normal temperature and in vacuum to obtain the magnetic composite material with the NdFeB doping concentration of 60 wt.%.

And taking 5g of dried cycloolefin copolymer (COC) particles, dissolving the particles in a chloroform reagent, adding 45g of NdFeB micron particles, and stirring and ultrasonically processing to obtain a uniformly mixed colloidal solution. Drying the magnetic composite material with high specific surface area at normal temperature and drying the magnetic composite material in vacuum to obtain the magnetic composite material with the NdFeB doping concentration of 10 wt.%. The temperature of vacuum drying is 70 ℃, and the time is 24 h.

(2) Preparation of a magnetically structured preform

Dried PMMA pellets (100 g) were hot pressed at 145 ℃ for 10min, mechanically ground and drilled to obtain a cylindrical preform I (18 mm in diameter) having two through holes (6mm, 4 mm).

And (3) respectively hot-pressing the dried magnetic composite material in the step (1) at 120 and 110 ℃ for 10min, mechanically polishing to obtain cylindrical preforms II and III with diameters of 6mm and 4mm, and inserting the cylindrical preforms III into the cladding in the step (2) to obtain the magnetic structured preform.

(3) Preparation of micro-nano magnetic fiber

And (3) carrying out hot wire drawing on the magnetic structural prefabricated rod obtained in the step (2) to obtain the micro-nano magnetic fiber with the structure shown in figure 4F. The hot wire drawing temperature is 240 ℃, the traction speed is 0.5m/min, and the diameter of the prepared micro-nano magnetic fiber is 500 mu m.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

2. The method for preparing micro-nano magnetic fiber according to claim 1,

3. The method for preparing the micro-nano magnetic fiber according to claim 1 or 2, wherein the micro-nano magnetic fiber comprises a core layer and a cladding layer;

4. The method for preparing the micro-nano magnetic fiber according to any one of claims 1 to 3, wherein the micro-nano magnetic fiber further comprises a high-melting-point functional layer;

5. The method for preparing the micro-nano magnetic fiber according to any one of claims 1 to 4, wherein in the processing step, the magnetic structured preform is prepared by one or more methods selected from a film winding method, a hot pressing method, an extrusion molding method and a 3D printing method.

6. The method for preparing micro-nano magnetic fiber according to claim 5, wherein in the processing step, the method for preparing the magnetic structured preform further comprises one or more of the following methods: machining, assembling and thermosetting.

7. The method for preparing the micro-nano magnetic fiber according to claim 5 or 6, further comprising the following steps after the step of hot drawing:

8. The method for preparing the micro-nano magnetic fiber according to any one of claims 1 to 7, wherein in the compounding step, the magnetic composite material is magnetic composite material particles, a magnetic composite material film or magnetic composite material powder.

9. The method for preparing the micro-nano magnetic fiber according to any one of claims 1 to 8, wherein in the compounding step, the magnetic particles are compounded with the base material by a chemical method;

10. The method for preparing the micro-nano magnetic fiber according to any one of claims 1 to 8, wherein in the compounding step, the magnetic particles and the base material are compounded by a physical method;