Preparation method of low-fibrillation Lyocell fiber

Abstract

The invention discloses a preparation method of low-fibrillation Lyocell fibers, and belongs to the technical field of fiber preparation. The method comprises the following steps: obtaining Lyocell fiber filaments; the Lyocell fiber filaments are cut off, and Lyocell short fibers are prepared; lyocell short fibers are subjected to lapping forming and fiber web crosslinking treatment, and a Lyocell fiber web is obtained; after the Lyocell fiber web is subjected to post-treatment, the low-fibrillation Lyocell fiber is obtained, and the value range of the fineness of the low-fibrillation Lyocell fiber is 1.2 dtex-1. 6 dtex; the low-fibrillating Lyocell fiber is initially worn for more than or equal to 200 times, and the variable coefficient is less than or equal to 40%; the low-fibrillated Lyocell fiber has a rising trend along with the increase of the placement time, and the maximum value of the number of wet wear times is 800-1200; the initial pH value range of the low-fibrillating Lyocell fiber is 8-11, and the pH value of the low-fibrillating Lyocell fiber is greater than or equal to 6 in the shelf life. The Lyocell fiber prepared by the method has the advantages that the wet wear value of the cross-linked fiber is increased along with the increase of the placement time, the production energy consumption is low, the shelf life is long, the application performance is excellent, and the like.

Description

Technical Field

[0001] The invention relates to the technical field of fiber preparation, and in particular to a method for preparing low-fibrillation Lyocell fibers. Background Art

[0002] Lyocell fiber is a cellulose fiber produced by dry-jet wet spinning with N-methylmorpholine-N-oxide (NMMO) as solvent. Lyocell fiber uses wood pulp, bamboo pulp and cotton pulp as raw materials. During the preparation process, the recovery rate of N-methylmorpholine-N-oxide (NMMO) reaches more than 99.5%, which is economical and applicable. The production process is green and environmentally friendly and pollution-free.

[0003] Lyocell fibers have high crystallinity and orientation. They easily absorb water and swell in a wet environment, which destroys the hydrogen bonds between the fibrils and weakens the lateral bonding force. Therefore, under the action of external mechanical forces, the fibrils will separate from each other, peeling off the fiber surface and causing fibrillation. The fibrillation tendency of Lyocell fibers causes pilling in textiles during washing, which seriously limits the application of Lyocell fibers. Summary of the invention

[0004] In view of this, the present invention provides a method for preparing low-fibrillation Lyocell fibers. The Lyocell fibers prepared by this method have the advantages of increased wet wear value of cross-linked fibers with increasing storage time, low production energy consumption, long shelf life, excellent application performance, etc., and are therefore more suitable for practical use.

[0005] In order to achieve the above object, the technical scheme of the preparation method of low fibrillation Lyocell fiber provided by the present invention is as follows:

[0006] The method for preparing low fibrillation Lyocell fiber provided by the present invention comprises the following steps:

[0007] Obtain Lyocell fiber filament;

[0008] Cutting the Lyocell fiber filaments to obtain Lyocell short fibers;

[0009] The Lyocell short fibers are laid and formed into a web and subjected to a fiber web cross-linking treatment to obtain a Lyocell fiber web, wherein the cross-linking treatment includes an alkali auxiliary agent treatment and a cross-linking agent treatment; during the cross-linking agent treatment, the effective component of the cross-linking agent is 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt, and the content of the effective component of the cross-linking agent on the Lyocell short fibers is in the range of 10kg / t fiber to 50kg / t fiber;

[0010] After the Lyocell fiber web is post-treated, the low-fibrillation Lyocell fiber is obtained, wherein:

[0011] The fineness of the low fibrillated Lyocell fiber ranges from 1.2 dtex to 1.6 dtex;

[0012] The low fibrillation Lyocell fiber is initially worn ≥200 times and has a coefficient of variation ≤40%;

[0013] The low fibrillation Lyocell fiber shows an increasing trend with the increase of placement time, and the maximum number of wet wear times is 800-1200 times;

[0014] The initial pH value range of the low fibrillation Lyocell fiber is 8-11, and the pH of the low fibrillation Lyocell fiber is ≥6 during the shelf life.

[0015] The method for preparing low-fibrillation Lyocell fibers provided by the present invention can be further implemented by adopting the following technical measures.

[0016] Preferably, the Lyocell short fibers are laid out and cross-linked to obtain a Lyocell fiber web, wherein the cross-linking treatment includes the steps of alkali auxiliary agent treatment and cross-linking agent treatment.

[0017] The alkali auxiliary agent treatment is processed via a first circulation system;

[0018] The cross-linking agent treatment is processed via a second circulation system;

[0019] The first circulation process and the second circulation process are two independent circulation systems.

[0020] Preferably, the circulation system comprises a circulation unit and a circulation tank.

[0021] The circulation unit comprises a first pressing roller and a second pressing roller, and the Lyocell fiber to be treated is pressed out from between the first pressing roller and the second pressing roller to obtain the pressed Lyocell fiber and the pressed solution.

[0022] The pressed solution is returned to the circulation tank.

[0023] As a preference,

[0024] The circulation unit includes at least one circulation unit monomer, and the circulation tank includes a circulation tank monomer.

[0025] The liquid outlet of the circulation unit cell is communicated with the liquid inlet of the circulation tank cell, and the liquid outlet of the circulation tank cell is communicated with the liquid inlet of the circulation unit cell.

[0026] As a preference,

[0027] The circulation unit comprises n circulation unit monomers and n circulation tank monomers, wherein n is a natural number.

[0028] The liquid outlet of the first circulation unit monomer is communicated with the liquid inlet of the first circulation tank monomer, and the liquid outlet of the first circulation tank monomer is communicated with the liquid inlet of the second circulation unit monomer;

[0029] The liquid outlet of the second circulation unit monomer is communicated with the liquid inlet of the second circulation tank monomer, and the liquid outlet of the second circulation tank monomer is communicated with the liquid inlet of the third circulation unit monomer;

[0030] And so on.

[0031] The liquid outlet of the last circulation unit monomer is communicated with the liquid inlet of the last circulation tank monomer, and the liquid outlet of the last circulation tank monomer is communicated with the liquid inlet of the first circulation unit monomer.

[0032] As a preference,

[0033] The applied temperature of the first circulation treatment system ranges from 0°C to 80°C;

[0034] The applied temperature of the second circulation treatment system ranges from 30°C to 100°C;

[0035] The fiber web cross-linking treatment is performed without heating equipment but only heat preservation, or the fiber web is subjected to heating equipment at a heating temperature of 60°C-100°C.

[0036] Preferably, the step of obtaining the low-fibrillation Lyocell fiber after the Lyocell fiber web is post-treated comprises the following steps:

[0037] The Lyocell fiber web is treated with an auxiliary agent to obtain an intermediate product;

[0038] After the intermediate product is dried, the low-fibrillation Lyocell fiber is obtained, wherein the pH of the low-fibrillation Lyocell fiber is ≥9.

[0039] Preferably, in the step of obtaining the intermediate product after the Lyocell fiber web is treated with an auxiliary agent, the auxiliary agent treatment is applying the auxiliary agent in an oil agent, the pH value range of the oil agent is 4-8, and the pH value range after applying the auxiliary agent in the oil agent is 5-12.

[0040] Preferably, in the step of obtaining the low-fibrillation Lyocell fiber after the intermediate product is dried, an auxiliary agent is applied during the drying process, and the content of the active ingredient of the auxiliary agent is at least 30 mmol / kg of fiber.

[0041] Preferably, the auxiliary agent is selected from sodium bicarbonate, sodium carbonate, ammonia water, ammonium chloride, borate, boric acid, hexamethylenetetramine, potassium hydrogen phthalate, aminoacetic acid, phosphate, hydrogen phosphate or dihydrogen phosphate, or a mixture of the above-mentioned solutions.

[0042] Preferably, between the step of forming a web of Lyocell short fibers and subjecting the web to cross-linking treatment to obtain a Lyocell fiber web and the step of post-treating the Lyocell fiber web to obtain the low-fibrillation Lyocell fibers, there is also a step of cleaning the Lyocell fiber web with a cleaning agent.

[0043] Preferably, the cleaning agent is selected from water or an acidic solution, and the mass percentage of the solute in the acidic solution ranges from 0.005% to 2.5%.

[0044] Preferably, the acid in the acidic solution is selected from one or more of acetic acid, hydrochloric acid, sulfuric acid and oxalic acid.

[0045] As a preference,

[0046] The fiber pH test method includes the following steps: weigh 1.0±0.05g of fiber and place it in a beaker, then weigh 10.0±0.5g of desalted water and pour it into the beaker containing the fiber to allow the fiber to fully contact the water, seal the beaker with a lid or sealing film, place it at room temperature for 12 hours, take out the fiber, drain the excess water, and test the pH value of the solution with a pH meter. It is worth noting that the pH meter needs to be calibrated in advance.

[0047] As a preference,

[0048] The fiber aging test method includes the following steps: weighing 10g of low fibrillation fiber, placing the low fibrillation fiber in a constant temperature and humidity chamber for aging, the aging temperature is 40°C, the aging humidity is 80%, sampling is performed every 7 days, and the wet wear times and fiber pH value are tested. The final wet wear times of the fiber <200 times is taken as the failure index, and the final value of the aging time is obtained.

[0049] The crosslinking agent in the low fibrillation Lyocell fiber prepared by the preparation method of the low fibrillation Lyocell fiber provided by the present invention does not react completely with the cellulose. During the placement process or in the subsequent wet treatment process (dyeing treatment), the crosslinking agent will gradually react with the fiber. The added auxiliary agent will promote the crosslinking reaction and protect the fiber to prevent the acidic substances produced by the reaction from damaging the fiber, so that the crosslinking effect is in a state of increasing. Therefore, the low fibrillation Lyocell fiber can be prepared, wherein the fineness of the low fibrillation Lyocell fiber ranges from 1.2dtex to 1.6dtex; the initial wear times of the low fibrillation Lyocell fiber are ≥200 times, and the coefficient of variation is ≤40%; the low fibrillation Lyocell fiber shows an upward trend with the increase of the placement time, and the maximum number of wet wear times is 800-1200 times; the initial pH value range of the low fibrillation Lyocell fiber is 8-11, and the pH of the low fibrillation Lyocell fiber is ≥6 during the shelf life. DETAILED DESCRIPTION

[0050] In view of this, the present invention provides a method for preparing low-fibrillation Lyocell fibers. The Lyocell fibers prepared by this method have the advantages of increased wet wear value of cross-linked fibers with increasing storage time, low production energy consumption, long shelf life, excellent application performance, etc., and are therefore more suitable for practical use.

[0051] After arduous efforts, the inventor discovered that

[0052] Many researchers have done a lot of research in this area, trying to find ways to reduce its fibrillation tendency. Among them, the products that have been successfully marketed are Lenzing's Lyocell LF and Tencel A100 cross-linked fibers. The cross-linking agent used in Lyocell LF cross-linked fiber is 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt (NHDT), and the cross-linking agent used in Tencel A100 cross-linked fiber is 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAHT).

[0053] Some technologies use NHDT as a crosslinking agent, and the fiber contacts the crosslinking agent in the form of filament bundles and reacts, and the process is called "tow crosslinking". However, the "tow crosslinking" process has the disadvantages of high equipment cost and large floor space.

[0054] Some technologies use NHDT as a crosslinking agent and apply a buffer to the fiber to make its crosslinking performance have a certain stability, but in general, the fiber wet wear value is constantly decreasing. In later applications, the crosslinking performance is seriously reduced, thus affecting the use.

[0055] The fibers are in contact with the crosslinking agent in the form of short fibers after being cut and react, and the process is called "short fiber crosslinking". The present invention is to lay the cut short fibers into a fiber mesh, and then perform a crosslinking treatment and an oiling treatment. In some technologies for fiber mesh forming, it is mentioned that a crosslinking process is used for the NHDT crosslinking agent so that the fiber contains a large amount of crosslinking agent that has not completely reacted, and an auxiliary agent is applied before or during drying. In this way, during the placement process or in the subsequent wet treatment process (dyeing treatment), the crosslinking agent will gradually react with the fiber. The added auxiliary agent will promote the crosslinking reaction and protect the fiber, avoiding the acidic substances produced by the reaction from damaging the fiber, so that the crosslinking effect is in a state of increasing. As a result, the wet wear value of the low fibrillation fiber is in a state of long-term and stable growth, which can greatly improve the application performance of the low fibrillation fiber and extend the shelf life of the fiber.

[0056] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the preparation method of a low fibrillation Lyocell fiber proposed by the present invention, its specific implementation method, structure, characteristics and effects in combination with the preferred embodiment. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0057] The term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B. Specifically, it is understood that: A and B may be included at the same time, A may exist alone, or B may exist alone, and any of the above three situations may be met.

[0058] The method for preparing low-fibrillation Lyocell fibers provided in an embodiment of the present invention comprises the following steps:

[0059] Step S1: obtaining Lyocell fiber filaments;

[0060] Step S2: cutting the Lyocell fiber filaments to obtain Lyocell short fibers;

[0061] Step S3: Lyocell staple fibers are laid out and cross-linked to obtain a Lyocell fiber web, wherein the cross-linking treatment includes an alkali auxiliary agent treatment and a cross-linking agent treatment; during the cross-linking agent treatment, the effective component of the cross-linking agent is 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt, and the content of the effective component of the cross-linking agent on the Lyocell staple fibers is in the range of 10kg / t fiber to 50kg / t fiber;

[0062] Step S4: After post-treatment of the Lyocell fiber web, low fibrillation Lyocell fibers are obtained, wherein:

[0063] The fineness of low fibrillated Lyocell fibers ranges from 1.2dtex to 1.6dtex;

[0064] The initial wear times of low fibrillation Lyocell fiber are ≥200 times and the coefficient of variation is ≤40%;

[0065] The low fibrillation Lyocell fiber showed an increasing trend with the increase of placement time, and the maximum number of wet abrasion times was between 800 and 1200 times;

[0066] The initial pH value range of the low fibrillation Lyocell fiber is 8-11, and the pH of the low fibrillation Lyocell fiber is ≥6 during the shelf life.

[0067] The crosslinking agent in the low fibrillation Lyocell fiber prepared by the preparation method of the low fibrillation Lyocell fiber provided by the present invention does not react completely with the cellulose. During the placement process or in the subsequent wet treatment process (dyeing treatment), the crosslinking agent will gradually react with the fiber. The added auxiliary agent will promote the crosslinking reaction and protect the fiber to prevent the acidic substances produced by the reaction from damaging the fiber, so that the crosslinking effect is in a state of increasing. Therefore, the low fibrillation Lyocell fiber can be prepared, wherein the fineness of the low fibrillation Lyocell fiber ranges from 1.2dtex to 1.6dtex; the initial wear times of the low fibrillation Lyocell fiber are ≥200 times, and the coefficient of variation is ≤40%; the low fibrillation Lyocell fiber shows an upward trend with the increase of the placement time, and the maximum number of wet wear times is 800-1200 times; the initial pH value range of the low fibrillation Lyocell fiber is 8-11, and the pH of the low fibrillation Lyocell fiber is ≥6 during the shelf life.

[0068] Among them, Lyocell short fibers are laid into a web and subjected to a fiber web cross-linking treatment to obtain a Lyocell fiber web, wherein the cross-linking treatment includes the steps of alkali agent treatment and cross-linking agent treatment, the alkali agent treatment is processed via a first circulation system; the cross-linking agent treatment is processed via a second circulation system; wherein the first circulation treatment and the second circulation treatment are two independent circulation systems.

[0069] The circulation system includes a circulation unit and a circulation tank. The circulation unit includes a first pressing roller and a second pressing roller, and the Lyocell fiber to be processed is pressed out from between the first pressing roller and the second pressing roller to obtain the pressed Lyocell fiber and the pressed solution, and the pressed solution flows back to the circulation tank.

[0070] The circulation unit includes at least one circulation unit monomer, the circulation tank includes a circulation tank monomer, the liquid outlet of the circulation unit monomer is connected to the liquid inlet of the circulation tank monomer, and the liquid outlet of the circulation tank monomer is connected to the liquid inlet of the circulation unit monomer.

[0071] Among them, the circulation unit includes n circulation unit monomers and n circulation tank monomers, wherein n is a natural number, the liquid outlet of the first circulation unit monomer is connected to the liquid inlet of the first circulation tank monomer, and the liquid outlet of the first circulation tank monomer is connected to the liquid inlet of the second circulation unit monomer; the liquid outlet of the second circulation unit monomer is connected to the liquid inlet of the second circulation tank monomer, and the liquid outlet of the second circulation tank monomer is connected to the liquid inlet of the third circulation unit monomer; and so on, the liquid outlet of the last circulation unit monomer is connected to the liquid inlet of the last circulation tank monomer, and the liquid outlet of the last circulation tank monomer is connected to the liquid inlet of the first circulation unit monomer.

[0072] Among them, the applied temperature range of the first circulation treatment system is 0℃-80℃; the applied temperature range of the second circulation treatment system is 30℃-100℃; among them, the fiber web cross-linking treatment does not pass through the heating equipment but only keeps warm, or, passes through the heating equipment, the heating temperature is 60℃-100℃.

[0073] The process of obtaining low-fibrillation Lyocell fibers after post-treatment of the Lyocell fiber web includes the following steps: the Lyocell fiber web is treated with an auxiliary agent to obtain an intermediate product; the intermediate product is dried to obtain low-fibrillation Lyocell fibers, wherein the pH of the low-fibrillation Lyocell fibers is ≥9.

[0074] Among them, in the step of obtaining the intermediate product after the Lyocell fiber web is treated with an additive, the additive treatment is to apply the additive in an oil agent, the pH value range of the oil agent is 4-8, and the pH value range after applying the additive in the oil agent is 5-12.

[0075] Among them, in the step of obtaining low-fibrillation Lyocell fibers after the intermediate product is dried, an auxiliary agent is applied during the drying process, and the content of the effective ingredient of the auxiliary agent is at least 30 mmol / kg of fiber.

[0076] The auxiliary agent is selected from one or a mixture of sodium bicarbonate, sodium carbonate, ammonia water, ammonium chloride, borate, boric acid, hexamethylenetetramine, potassium hydrogen phthalate, aminoacetic acid, phosphate, hydrogen phosphate or dihydrogen phosphate.

[0077] Among them, between the step of forming a Lyocell short fiber web and undergoing a fiber web cross-linking treatment to obtain a Lyocell fiber web and the step of obtaining low-fibrillation Lyocell fibers after post-treatment of the Lyocell fiber web, there is also a step of using a cleaning agent to clean the Lyocell fiber web.

[0078] The cleaning agent is selected from water or an acidic solution, and the mass percentage of the solute in the acidic solution ranges from 0.005% to 2.5%.

[0079] The acid in the acidic solution is selected from one or more of acetic acid, hydrochloric acid, sulfuric acid and oxalic acid.

[0080] The fiber pH value test method includes the following steps: weigh 1.0±0.05g of fiber and place it in a beaker, then weigh 10.0±0.5g of desalted water and pour it into the beaker containing the fiber to allow the fiber to fully contact with water, seal the beaker with a lid or sealing film, place it at room temperature for 12 hours, take out the fiber, drain the excess water, and test the pH value of the solution with a pH meter. It is worth noting that the pH meter needs to be calibrated in advance.

[0081] The fiber aging test method includes the following steps: weighing 10g of low fibrillation fiber, placing the low fibrillation fiber in a constant temperature and humidity chamber for aging, the aging temperature is 40°C, the aging humidity is 80%, sampling is performed every 7 days, and the wet wear times and fiber pH value are tested. The final wet wear times of the fiber <200 times is taken as the failure index, and the final value of the aging time is obtained.

[0082] Example 1

[0083] The low fibrillation fiber was prepared by the existing "fiber web cross-linking" process, and then the low fibrillation fiber was cleaned with acetic acid, and then leached and dried and packaged, and the sodium carbonate was controlled to be 60mmol / kg fiber. The results are shown in Table 1.

[0084] Example 2

[0085] The low fibrillation fiber was prepared by the existing "fiber web cross-linking" process, and then the low fibrillation fiber was cleaned with sulfuric acid, and then leached, dried and packaged, and the concentration of dipotassium hydrogen phosphate was controlled to be 100mmol / kg fiber. The results are shown in Table 1.

[0086] Example 3

[0087] The low fibrillation fiber was prepared by the existing "fiber web cross-linking" process, and then the low fibrillation fiber was cleaned with sulfuric acid, and then added with an oil agent of sodium carbonate, sodium bicarbonate and dipotassium hydrogen phosphate, and finally unwrapped, dried and packaged, and the additive was controlled to be 80mmol / kg fiber. The results are shown in Table 1.

[0088] Example 4

[0089] The low fibrillation fiber was prepared by the existing "fiber web cross-linking" process, and then the low fibrillation fiber was cleaned with sulfuric acid, and then leached, dried and packaged after adding sodium carbonate and sodium bicarbonate. The additive was controlled to be 75mmol / kg fiber. The results are shown in Table 1.

[0090] Comparative Example 1

[0091] The low fibrillation fiber was prepared by the existing cross-linking process, and then the low fibrillation fiber was cleaned with sulfuric acid, and then treated with an additive-free oil agent, and finally unwrapped, dried and packaged. The sample was sampled and tested every day, and the results are shown in Table 1.

[0092] Table 1

[0093] Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Denier(dtex) 1.33 1.34 1.32 1.35 1.34 Initial wet wear times 400 210 300 240 220 Initial CV wet wear (%) 40 30 35 33 36 Maximum wet wear times 400 1200 930 880 1120 Initial fiber pH 7.8 10.5 9.8 9.0 10.3 Final fiber pH 5.3 7.5 6.8 6.2 7.3 Aging time (wet wear times < 200) 1 week 30 weeks 25 weeks 35 weeks 33 weeks

[0094] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0095] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing low fibrillation Lyocell fiber, characterized in that: The following steps are involved: Obtain Lyocell fiber filament; Cutting the Lyocell fiber filaments to obtain Lyocell short fibers; The Lyocell short fibers are laid and formed into a web and subjected to a fiber web cross-linking treatment to obtain a Lyocell fiber web, wherein the cross-linking treatment includes an alkali auxiliary agent treatment and a cross-linking agent treatment; during the cross-linking agent treatment, the effective component of the cross-linking agent is 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt, and the content of the effective component of the cross-linking agent on the Lyocell short fibers is in the range of 10kg / t fiber to 50kg / t fiber; After the Lyocell fiber web is post-treated, the low-fibrillation Lyocell fiber is obtained, wherein: The fineness of the low fibrillated Lyocell fiber ranges from 1.2 dtex to 1.6 dtex; The low fibrillation Lyocell fiber is initially worn ≥200 times and has a coefficient of variation ≤40%; The low fibrillation Lyocell fiber shows an increasing trend with the increase of placement time, and the maximum number of wet wear times is 800-1200 times; The initial pH value range of the low fibrillation Lyocell fiber is 8-11, and the pH of the low fibrillation Lyocell fiber is ≥6 during the shelf life.

2. The method for preparing low fibrillation Lyocell fiber according to claim 1, characterized in that: The Lyocell short fibers are laid out and cross-linked to obtain a Lyocell fiber web, wherein the cross-linking treatment includes the steps of alkali auxiliary agent treatment and cross-linking agent treatment. The alkali auxiliary agent treatment is processed via a first circulation system; The cross-linking agent treatment is processed via a second circulation system; The first circulation process and the second circulation process are two independent circulation systems.

3. The method for preparing low fibrillation Lyocell fiber according to claim 2, characterized in that: The circulation system comprises a circulation unit and a circulation tank. The circulation unit comprises a first pressing roller and a second pressing roller, and the Lyocell fiber to be treated is pressed out from between the first pressing roller and the second pressing roller to obtain the pressed Lyocell fiber and the pressed solution. The pressed solution is returned to the circulation tank.

4. The method for preparing low fibrillation Lyocell fiber according to claim 3, characterized in that: The circulation unit includes at least one circulation unit monomer, and the circulation tank includes a circulation tank monomer. The liquid outlet of the circulation unit cell is communicated with the liquid inlet of the circulation tank cell, and the liquid outlet of the circulation tank cell is communicated with the liquid inlet of the circulation unit cell.

5. The method for preparing low fibrillation Lyocell fiber according to claim 3, characterized in that: The circulation unit comprises n circulation unit monomers and n circulation tank monomers, wherein n is a natural number. The liquid outlet of the first circulation unit monomer is communicated with the liquid inlet of the first circulation tank monomer, and the liquid outlet of the first circulation tank monomer is communicated with the liquid inlet of the second circulation unit monomer; The liquid outlet of the second circulation unit monomer is communicated with the liquid inlet of the second circulation tank monomer, and the liquid outlet of the second circulation tank monomer is communicated with the liquid inlet of the third circulation unit monomer; And so on. The liquid outlet of the last circulation unit monomer is communicated with the liquid inlet of the last circulation tank monomer, and the liquid outlet of the last circulation tank monomer is communicated with the liquid inlet of the first circulation unit monomer.

6. The method for preparing low fibrillation Lyocell fiber according to claim 2, characterized in that: The applied temperature of the first circulation treatment system ranges from 0°C to 80°C; The applied temperature of the second circulation treatment system ranges from 30°C to 100°C; The fiber web cross-linking treatment is performed without heating equipment but only heat preservation, or the fiber web is subjected to heating equipment at a heating temperature of 60°C-100°C.

7. The method for preparing low fibrillation Lyocell fiber according to claim 1, characterized in that: After the Lyocell fiber web is post-treated, the process of obtaining the low-fibrillation Lyocell fiber includes the following steps: The Lyocell fiber web is treated with an auxiliary agent to obtain an intermediate product; After the intermediate product is dried, the low-fibrillation Lyocell fiber is obtained, wherein the pH of the low-fibrillation Lyocell fiber is ≥9.

8. The method for preparing low fibrillation Lyocell fiber according to claim 7, characterized in that: In the step of obtaining the intermediate product after the Lyocell fiber web is treated with an auxiliary agent, the auxiliary agent treatment is to apply the auxiliary agent in an oil agent, the pH value range of the oil agent is 4-8, and the pH value range after applying the auxiliary agent in the oil agent is 5-12.

9. The method for preparing low fibrillation Lyocell fiber according to claim 7, characterized in that: In the step of obtaining the low-fibrillation Lyocell fiber after the intermediate product is dried, an auxiliary agent is applied during the drying process, and the content of the active ingredient of the auxiliary agent is at least 30 mmol / kg of fiber.

10. The method for preparing low fibrillation Lyocell fiber according to claim 7, characterized in that: The auxiliary agent is selected from a solution prepared by mixing one or more of sodium bicarbonate, sodium carbonate, ammonia water, ammonium chloride, borate, boric acid, hexamethylenetetramine, potassium hydrogen phthalate, aminoacetic acid, phosphate, hydrogen phosphate or dihydrogen phosphate; Preferably, between the step of forming the Lyocell short fiber web by laying and cross-linking the Lyocell fiber web to obtain the Lyocell fiber web and the step of obtaining the low-fibrillation Lyocell fiber by post-treating the Lyocell fiber web, there is also a step of using a cleaning agent to clean the Lyocell fiber web; Preferably, the cleaning agent is selected from water or an acidic solution, and the mass percentage of the solute in the acidic solution ranges from 0.005% to 2.5%; Preferably, the acid in the acidic solution is selected from one or more of acetic acid, hydrochloric acid, sulfuric acid and oxalic acid; Preferably, the fiber pH value test method includes the following steps: weigh 1.0±0.05g of fiber and place it in a beaker, then weigh 10.0±0.5g of desalted water and pour it into the beaker containing the fiber to allow the fiber to fully contact with the water, seal the beaker with a lid or sealing film, place it at room temperature for 12 hours, take out the fiber, and drain the excess water, and use a pH meter to test the pH value of the solution. It is worth noting that the pH meter needs to be calibrated in advance; Preferably, the fiber aging test method comprises the following steps: weighing 10g of low fibrillation fiber, placing the low fibrillation fiber in a constant temperature and humidity chamber for aging, the aging temperature is 40°C, the aging humidity is 80%, sampling is performed every 7 days, and the wet abrasion times and fiber pH value are tested. The final wet abrasion times of the fiber <200 times is taken as the failure index, and the final value of the aging time is obtained.