A differential cellulose fiber and its preparation method

Abstract

This solution provides a differential cellulose fiber and its preparation method. The cellulose pulp is mixed evenly with an organic solvent system to obtain a mixed system. After raising the temperature of the mixed system to the dissolution temperature of cellulose, it is filtered and degassed to obtain a fiber dope. The organic solvent system contains an ionic liquid and a strongly polar co-solvent, and the co-solvent is a solvent that can form an interaction with the ions of the ionic solution and will not cause the cellulose to solidify and precipitate. The fiber dope is extruded through a spinneret by a spinning process to obtain fiber filaments. The fiber filaments are immersed in a coagulation bath composed of a strongly polar anti-solvent for coagulation and drawing, and then are washed with water, oiled, dried, and wound to obtain differential fibers. The differential fibers have a differential microstructure, which realizes the synergistic optimization of the fiber structure and performance and expands its application fields by bidirectionally and dynamically regulating the recombination of cellulose hydrogen bonds through the solvent and the anti-solvent, breaking through the geometric limitation of the spinneret holes of profiled fibers.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber preparation, and in particular to a differentiated cellulose fiber and a preparation method thereof. Background Art

[0002] Cellulose is the most abundant natural polymer material on earth. The structure and composition of cellulose fibers prepared with cellulose as raw material are similar to those of cotton fibers, and its performance in all aspects is better than that of cotton fibers. It has the advantages of strong moisture absorption, excellent air permeability, and comfortable feel. It is widely used in textile and clothing, home textiles, medical care, industry and other fields.

[0003] In order to enhance the competitiveness of the textile industry and meet the needs of consumption upgrades, cellulose fiber materials are developing in the direction of high value, greenness, and intelligence. Differentiated fibers refer to fibers that are physically or chemically modified on the basis of the original fiber composition, so that the fiber morphology, structure, and physical and chemical properties are significantly different from conventional fibers, thereby increasing their added value and market competitiveness. From the perspective of morphology and structure, differentiated fibers mainly include shaped fibers, composite fibers, and fine (denier) fibers. At present, the preparation of differentiated fibers is usually carried out by modifying the fibers using spinnerets with non-circular geometric shapes or by chemical methods such as copolymerization, grafting, cross-linking, dissolution, and electroplating, thereby giving the fibers certain functionality. For example, the presence of an air cavity inside the hollow fiber improves the fluffiness and warmth of the fiber; the groove structure on the fiber surface with Y-shaped, cross-shaped, and other cross-sections can quickly guide moisture to diffuse from the skin surface to the outside, giving it good moisture conductivity and air permeability; the Na + and Ca 2+ Grafting onto cellulose fibers helps reduce the flammability of textile materials and obtain flame-retardant functional fiber materials. However, these technical processes are complicated, costly, require high equipment, have poor fiber structure stability, and have insignificant functional effects, which is not conducive to large-scale production and application of fibers.

[0004] Of course, there are also technologies for regenerating cellulose to prepare differential cellulose. At present, reports on cellulose regeneration mainly focus on the study of the influence of anti-solvent diffusion behavior on the formation of regenerated cellulose, and regulating the structure and properties of regenerated cellulose materials by changing process parameters (such as coagulation bath composition, polarity, temperature, etc.). For example, CN117904737A proposes a method of using the polarity of the coagulation bath to sequentially construct a three-stage continuous gradient coagulation bath system to achieve gradient porous regenerated cellulose, which is a conventional method of controlling the coagulation rate of cellulose solution by the polarity of the coagulation bath (anti-solvent).

[0005] However, the regeneration process of cellulose is essentially a process of double diffusion of solvent and anti-solvent molecules to achieve the recombination of intra / inter-chain hydrogen bonds of cellulose molecules. The diffusion behaviors of the solvent and the anti-solvent both play a crucial role in the reconstruction of the hydrogen bond network on the cellulose hydroxyl groups. It is obviously insufficient to study the construction of regenerated cellulose only from the anti-solvent diffusion behavior. Moreover, the dissociation and recombination of strong hydrogen bonds between the solvent and cellulose are the key to realizing cellulose regeneration. However, there is no research in the prior art on bidirectionally and dynamically coordinating the hydrogen bond recombination of cellulose by the solvent and the anti-solvent to construct cellulose materials with multi-scale microstructural differences. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing differential cellulose fibers and its application. By bidirectionally and dynamically coordinating the hydrogen bond recombination of cellulose by the solvent and the anti-solvent, the geometric limitation of the spinneret holes of profiled fibers is broken through. Under the traditional spinneret holes, cellulose fibers with microstructural differences can be constructed, realizing the coordinated optimization of the fiber structure and performance and expanding its application fields.

[0007] To achieve the above purpose, the technical solution of the present invention provides a method for preparing differential cellulose fibers, including the following steps:

[0008] (1) Preparation of fiber dope: Mix cellulose pulp with an organic solvent system evenly to obtain a mixed system. Raise the temperature of the mixed system to the dissolution temperature of cellulose, and then obtain the fiber dope through filtration and degassing. The organic solvent system contains an ionic liquid and a strongly polar co-solvent, and the co-solvent is a solvent that can form an interaction with the ions of the ionic solution and will not cause cellulose to solidify and precipitate.

[0009] (2) Preparation of differential fibers: Extrude the fiber dope through a spinneret by a spinning process to obtain fiber filaments. Immerse the fiber filaments in a coagulation bath composed of a strongly polar anti-solvent for coagulation and drawing, and obtain differential fibers through water washing, oil impregnation, drying, and winding. The differential fibers have differential microstructures.

[0010] This solution uses a strongly polar co-solvent and a strongly polar anti-solvent to coordinately regulate the hydrogen bond deconstruction process between the ions of the ionic liquid and cellulose, so as to obtain differential cellulose with different cellulose microstructures. The microstructures of the differential cellulose prepared by this solution are selected from one or more of multi-level porous, micro-cracked or ordered vertical stripe structures, and the morphologies of the microstructures in the differential cellulose are various.

[0011] In the step of "preparation of fiber dope":

[0012] In some embodiments, the cellulose pulp raw material is selected from the dissolving pulp of one or more raw materials of wheat straw, straw, eucalyptus, giant miscanthus or arundo donax, and the cellulose polymerization degree in the cellulose pulp raw material is 500 - 1500.

[0013] In this solution, the cellulose pulp is mixed evenly with an organic solvent system to obtain a mixed system. After the cellulose pulp is fully wetted, the temperature of the mixed system is raised to the dissolution temperature of cellulose so that the cellulose is completely dissolved. Subsequently, the mixed system after complete dissolution of cellulose is filtered and degassed to obtain a fiber dope.

[0014] In some embodiments, the mixing temperature of the cellulose pulp and the organic solvent system during the even mixing stage is 50 - 60 °C, the time for the cellulose pulp to be fully wetted is 0.5 - 1 h, the dissolution temperature of cellulose is 70 - 85 °C, and the cellulose concentration in the spinning dope is 8 - 15 wt%.

[0015] In some embodiments, the ionic liquid contained in the organic solvent system is at least one of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene acetate or 1,8 - diazabicyclo[5.4.0]undec - 7 - ene ethoxyacetate.

[0016] It should be noted that in this solution, 1,8 - diazabicyclo[5.4.0]undec - 7 - ene acetate or 1,8 - diazabicyclo[5.4.0]undec - 7 - ene ethoxyacetate of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene (DABCO) - type ionic liquids are selected as cellulose solvents based on their unique molecular structure, dissolution performance, and synergistic effect with co - solvents / anti - solvents.

[0017] In terms of molecular structure: DABCO is a bicyclic amidine compound. Its nitrogen atoms have lone pairs of electrons and relatively strong basicity (pKa≈12.8), which can form hydrogen bonds with the hydroxyl groups on the cellulose molecular chain, breaking the hydrogen bond network inside cellulose. Compared with traditional imidazole - type ionic liquids, the basicity of DABCO - type ionic liquids is more evenly distributed in the ring structure, and the dissolution of cellulose is more efficient. The anion in 1,8 - diazabicyclo[5.4.0]undec - 7 - ene acetate has a carboxylic acid group and has a strong ability to form hydrogen bonds with cellulose hydroxyl groups, being suitable for cellulose with low degree of polymerization; the anion of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene ethoxyacetate introduces an ethoxy group to enhance the hydrophilicity of the ionic liquid, being suitable for cellulose with high degree of polymerization. In terms of dissolution performance: the solubility of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene acetate in cellulose is as high as 15 wt%, and the solution viscosity is only 2000 - 3000 mPa·s; 1,8 - diazabicyclo[5.4.0]undec - 7 - ene ethoxyacetate can also dissolve cellulose well, and the solution has good fluidity, being suitable for subsequent spinning.

[0018] The co-solvents contained in the organic solvent system include strongly polar protic solvents and / or strongly polar aprotic solvents. Among them, the differences in polarity, molecular chain structure, dipole moment, surface groups, etc. between the same type of co-solvents will affect the strength of hydrogen bonding between components, especially the hydrogen bonding between ionic liquid and cellulose. It should be noted that the organic solvent system of this solution can contain only protic solvents, only aprotic solvents, or both protic solvents and aprotic solvents at the same time.

[0019] The co-solvents in the organic solvent system of this solution are selected from polar aprotic solvents such as dimethyl sulfoxide, sulfolane, N , N -dimethylformamide, N , N -dimethylacetamide, N -N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, 1-methylimidazole, 1-ethylimidazole or 1-propylimidazole, 1-n-butylimidazole, or polar protic solvents such as oxalic acid, acetic acid, methoxyacetic acid, ethoxyacetic acid, one or more of them.

[0020] In some embodiments, the mass ratio of the ionic liquid to the co-solvent in the organic solvent system is 10:(1 - 5). Since the role of the co-solvent in the organic solvent system of this solution is: to reduce the viscosity of the organic solvent system, to preferentially solvate the cations of the ionic liquid, and to have little influence on the hydrogen bonds between / within the cellulose molecular chains in the follow-up, therefore, the content of the co-solvent in this solution should not be too high. Once it exceeds a certain proportion, it will cause the cellulose to be insoluble. The purpose of controlling this proportion range in this solution is to enable the co-solvent to play its role when the cellulose is completely dissolved.

[0021] The strongly polar anti-solvent of this solution is selected from at least one of water, methanol, ethanol or dimethyl sulfoxide.

[0022] In some embodiments, by weight, when the organic solvent system is 100 parts, the anti-solvent is 400 - 600 parts. Preferably, the anti-solvent is 500 parts. It should be noted that the starting point of the cellulose regeneration process is the addition of the anti-solvent. The anti-solvent is the key to breaking the hydrogen bonding between cellulose and ionic liquid, and the co-solvent can cooperate with the anti-solvent to regulate the cellulose regeneration process from the solvent perspective. Generally, according to the requirements of the preparation process, the proportion of the anti-solvent is much higher than that of the solvent system. In this solution, the mass ratio of the organic solvent system to the anti-solvent is set, and the solidification process of the cellulose solution can be observed at this ratio.

[0023] Polar aprotic cosolvents can promote the solvation of cations in ionic liquids, thereby increasing the number of free anions in the system, resulting in an increase in the binding sites between the ionic liquid and cellulose; at this time, ethanol with strong polarity and large molecular volume (compared with molecules such as water and methanol) is used as an antisolvent to regenerate cellulose. On the one hand, ethanol forms hydrogen bond interactions with the polar aprotic cosolvent and the anion of the ionic liquid as a hydrogen bond donor. On the other hand, as a hydrogen bond acceptor, it competes with the polar aprotic cosolvent for the hydrogen bond sites on the cation of the ionic liquid. The hydrogen bond binding and hydrogen bond competition between ethanol and the cosolvent provide sufficient time for the hydrogen bond deconstruction between the ionic liquid and cellulose. The intermolecular / intramolecular hydrogen bond rearrangement structure of cellulose molecules is relatively regular, the fiber microstructure is relatively dense, and the defect structures formed on the surface are mostly micropores and microcracks (2 - 10 nm).

[0024] Polar protic solvents can form hydrogen bond interactions with both the anions and cations of ionic liquids, reducing the number of free anions in the system and resulting in a decrease in the binding sites between the ionic liquid and cellulose; at the same time, using water or methanol with strong polarity and small molecular volume as an antisolvent to regenerate cellulose, it competes with the cosolvent for the hydrogen bond sites on the anions and cations of the ionic liquid, increasing the diffusion rate of the ionic liquid towards the antisolvent during cellulose regeneration, promoting the intermolecular / intramolecular hydrogen bond rearrangement of cellulose molecules, and resulting in a relatively loose structure of the formed cellulose. Under the action of stretching in the spinning process, a relatively regular vertical stripe defect structure is formed.

[0025] In other words, the morphology of the microstructure of the differentiated cellulose is determined by the types of the cosolvent and the antisolvent. When a strong polar protic solvent is selected as the cosolvent and / or a solvent with a small molecular volume is selected as the antisolvent, the microstructure of the differentiated cellulose is a regular vertical stripe structure. Preferably, the combination of ethoxyacetic acid as the cosolvent and water as the antisolvent or the combination of acetic acid as the cosolvent and methanol as the antisolvent; when a strong polar aprotic solvent is selected as the cosolvent and a solvent with a large molecular volume is selected as the antisolvent, the microstructure of the differentiated cellulose is a microporous and microcracked structure. Preferably, N , N the combination of N,N - dimethylacetamide as the cosolvent and ethanol as the antisolvent.

[0026] Furthermore, the size, quantity, and distribution of the microstructure of the differentiated cellulose are determined by the proportions of the ionic liquid, the cosolvent, and the antisolvent. If it is necessary to increase the quantity of the microstructure of the microporous, microcracked, and vertical stripe structures, increase the proportion of the cosolvent in the organic solvent system to further exert the role of the cosolvent, reduce the viscosity of the organic solvent system, and improve the mass transfer performance of the ionic solution.

[0027] In addition, the present technical solution provides a differential cellulose fiber, which is prepared according to the above preparation method and has a differential microstructure, wherein the microstructure is selected from one or more of a hierarchical porous structure, a microcracked structure, or an ordered vertical stripe structure.

[0028] In some embodiments, the morphology of the microstructure is changed by changing the types of the co-solvent and the anti-solvent.

[0029] In some embodiments, the size, quantity, and distribution of the microstructure are changed by changing the ratios of the ionic liquid, the co-solvent, and the anti-solvent.

[0030] It should be noted that the differential cellulose fiber provided by the present solution can be applied to the fields of adsorption materials, humidity-sensitive, light-sensitive and other intelligent textile materials according to the morphological characteristics of the microstructure.

[0031] Compared with the prior art, the present technical solution has the following characteristics and beneficial effects:

[0032] (1) The present invention provides a simple and effective physical method, which can stably and efficiently prepare differential cellulose fibers. This technical solution breaks through the geometric limitation of the spinneret holes of profiled fibers, and fiber materials with different morphological structures can be obtained under traditional circular spinneret holes. The raw materials and reagents used in the whole preparation process are green, environmentally friendly, and widely sourced. The process flow is simple and efficient, and it is easy to realize industrial production.

[0033] (2) The differential fiber with the microstructure described in the present invention, according to the morphological characteristics of the microstructure, includes structures such as a microporous structure, a microcracked structure, or an ordered vertical stripe structure, and has a significant regulating effect on humidity and light. Specifically, the nanoscale pore structure and microcracked structure provide channels for the diffusion of water molecules, enabling the material to quickly respond to changes in environmental humidity, and increasing the surface area of the fiber, greatly enhancing its adsorption and filtration capabilities; the ordered vertical stripe structure enhances the optical anisotropy of the fiber material, and thus can regulate the characteristics of light absorption, reflection, and transmission. The differential fiber with the microstructure prepared by the present invention can be applied to the fields of adsorption materials, humidity-sensitive, light-sensitive and other intelligent textile materials, meeting the urgent needs of the national chemical fiber industry for the development of fiber materials towards green, high-end, and intelligent directions.

[0034] (3) The technology of the present invention realizes the construction of microstructurally differentiated fibers through the synergistic regulation of the diffusion behavior of ionic liquids by a strongly polar co-solvent and an anti-solvent. Specifically, the co-solvent helps to reduce the viscosity of the ionic liquid and preferentially solvates its cations, thereby promoting the diffusion of the ionic liquid solvent in the anti-solvent. In addition, due to the differences in the concentration gradients and diffusion coefficients among the components in the system, the anti-solvent molecules diffuse towards the cellulose solution and form hydrogen bond interactions of different strengths with the ionic liquid, co-solvent molecules, and cellulose molecular chains. Both the strongly polar co-solvent and the anti-solvent can form hydrogen bond bindings with the ionic liquid, realizing the two-way regulation of cellulose hydrogen bond recombination. Under the action of the stretching process in wet spinning or dry-jet wet spinning, different spatial orientations are formed, resulting in fibers with various morphological structures. Compared with the traditional technology for preparing differentiated fibers, this technical solution has a short process flow, strong operability, and a wide controllable range of fiber morphological structures, and has high practical value and good development prospects. Description of the Drawings

[0035] Figure 1 are the microscopic morphology diagrams of the differentiated cellulose fibers prepared in Examples 1, 3, 4, and 5. Specific Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0037] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following describes in detail the specific implementation methods, features, and performances of a method for preparing differentiated fibers and its applications proposed according to the present invention in conjunction with preferred embodiments. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0038] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art in the field to which the present invention belongs.

[0039] The methods in the following embodiments are all conventional methods unless otherwise specified; the materials or reagents in the following embodiments are all commercially available unless otherwise specified.

[0040] The present invention will be further described below by way of specific embodiments, but it is not intended to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0041] Example 1

[0042] Weigh 10 parts of eucalyptus pulp with a degree of polymerization of 650 by weight and add it to 90 parts of an organic solvent system. Mix and stir at 50 °C for 0.5 h. Among them, the organic solvent system is composed of 1,8-diazabicyclo[5.4.0]undec-7-ene acetate and N , N N,N-dimethylformamide with a mass ratio of 10:1. After the pulp is fully wetted, raise the temperature to 80 °C and continue stirring until the cellulose is completely dissolved. Then, obtain the spinning dope through precision filtration and vacuum degassing processes. Extrude the prepared spinning dope through a dry-jet wet spinning process through a circular spinneret into a coagulation bath composed of 500 parts of ethanol to regenerate and form primary fibers. Then, after conventional washing, oil immersion, drying, winding and other processes, obtain differential fibers with a microporous and microcracked structure on the surface as shown in Figure 1 A. The micro-nano scale structure can increase the fiber surface area and improve the adsorption of water molecules, gases, ions or organic pollutants, and has good application prospects in the fields of high-efficiency adsorption materials (such as sewage treatment, air purification) and functional textiles (such as moisture absorption, antibacterial).

[0043] Example 2

[0044] The difference between this example and Example 1 is that the organic solvent system is composed of 1,8-diazabicyclo[5.4.0]undec-7-ene acetate and N , N N,N-dimethylformamide with a mass ratio of 10:3. The remaining steps and parameters are the same as those in Example 1, and the microscopic morphology of the fiber surface obtained is similar to that in Example 1.

[0045] Example 3

[0046] The difference between this example and Example 1 is that the prepared spinning dope is extruded through a dry-jet wet spinning process through a circular spinneret into a coagulation bath composed of 500 parts of deionized water to regenerate and form primary fibers. The remaining steps and parameters are the same as those in Example 1, and differential fibers with a small number of vertical stripe structures on the surface as shown in Figure 1 B are obtained.

[0047] Example 4

[0048] The difference between this embodiment and Embodiment 3 is that the organic solvent system consists of 1,8-diazabicyclo[5.4.0]undec-7-ene acetate and acetic acid with a mass ratio of 10:1; the prepared spinning dope is extruded through a circular spinneret hole by a dry-jet wet spinning process and enters a coagulation bath composed of 500 parts of methanol for regeneration to form nascent fibers. The remaining steps and parameters are the same as those in Embodiment 3, and Figure 1 the differential fibers with more vertical stripe structures on the surface as shown in C in

[0049] Embodiment 5

[0050] The difference between this embodiment and Embodiment 4 is that the organic solvent system consists of 1,8-diazabicyclo[5.4.0]undec-7-ene acetate and ethoxyacetic acid with a mass ratio of 10:1. The remaining steps and parameters are the same as those in Embodiment 4, and Figure 1 the differential fibers with a large number of vertical stripe structures on the surface as shown in D in

[0051] Embodiment 6

[0052] The difference between this embodiment and Embodiment 5 is that the organic solvent system consists of 1,8-diazabicyclo[5.4.0]undec-7-ene ethoxyacetate and ethoxyacetic acid with a mass ratio of 10:1. The remaining steps and parameters are the same as those in Embodiment 5, and the microscopic morphology of the obtained fiber surface is similar to that in Embodiment 5.

[0053] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0054] The above embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A preparation method of a differential cellulose fiber, characterized in that, It includes the following steps: (1) Preparation of fiber dope: Mix cellulose pulp with an organic solvent system evenly to obtain a mixed system. Raise the temperature of the mixed system to the dissolution temperature of cellulose, and then obtain fiber dope through filtration and degassing. The organic solvent system contains an ionic liquid and a strongly polar co-solvent, and the co-solvent is a solvent that can form an interaction with the ions of the ionic solution and will not cause cellulose to solidify and precipitate; (2) Preparation of differential fiber: Extrude the fiber dope through a spinneret by a spinning process to obtain fiber filaments. Immerse the fiber filaments in a coagulation bath composed of a strongly polar anti-solvent for coagulation and stretching, and then obtain differential fibers through washing, oil impregnation, drying and winding. The differential fibers have a differential microstructure; When a strongly polar protic solvent is selected as the co-solvent and a solvent with a small molecular volume is selected as the anti-solvent, the microstructure of the differential cellulose is a regular vertical stripe structure; when a strongly polar aprotic solvent is selected as the co-solvent and a solvent with a large molecular volume is selected as the anti-solvent, the microstructure of the differential cellulose is a microporous and microcracked structure. If it is necessary to increase the number of microstructures of the microporous, microcracked and vertical stripe structures, increase the proportion of the co-solvent in the organic solvent system.

2. The preparation method of the differential cellulose fiber according to claim 1, characterized in that, The mixing temperature of the cellulose pulp and the organic solvent system during the even mixing stage is 50 - 60 °C, the time for the cellulose pulp to be fully wetted is 0.5 - 1 h, the dissolution temperature of cellulose is 70 - 85 °C, and the cellulose concentration in the spinning dope is 8 - 15 wt%.

3. The preparation method of the differential cellulose fiber according to claim 1, characterized in that, The ionic liquid contained in the organic solvent system is at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene acetate or 1,8-diazabicyclo[5.4.0]undec-7-ene ethoxyacetate.

4. The preparation method of the differential cellulose fiber according to claim 1, characterized in that, The co-solvent is selected from polar aprotic solvents such as dimethyl sulfoxide, sulfolane, N , N -dimethylformamide, N , N -dimethylacetamide, N -N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, 1-methylimidazole, 1-ethylimidazole or 1-propylimidazole, 1-n-butylimidazole, or polar protic solvents such as oxalic acid, acetic acid, methoxyacetic acid, ethoxyacetic acid, or one or more thereof.

5. The preparation method of the differential cellulose fiber according to claim 1, characterized in that, The mass ratio of the ionic liquid to the co-solvent in the organic solvent system is 10:(1 - 5).

6. The method for preparing the differentiated cellulose fiber according to claim 1, wherein The strongly polar anti-solvent is selected from at least one of water, methanol, ethanol or dimethyl sulfoxide.

7. The preparation method of the differential cellulose fiber according to claim 1, characterized in that By weight, when the organic solvent system is 100 parts, the anti-solvent is 400 - 600 parts.

8. The method for preparing the differential cellulose fiber according to claim 1, wherein Change the morphology of the microstructure by changing the types of the co-solvent and the anti-solvent, and change the size, number and distribution of the microstructure by changing the proportions of the ionic liquid, the co-solvent and the anti-solvent.

9. A differential cellulose fiber prepared by the preparation method of the differential cellulose fiber according to any one of claims 1 to 8 above, wherein the microstructure is selected from one or more of a hierarchical porous structure, a microcracked structure or an ordered vertical stripe structure.

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