Solution coagulation molding method and long fiber spinning method using natural high molecular
By using inorganic salt solutions such as bicarbonate as coagulation baths, combined with urea and thiourea additives, the problem of recovering natural polymer solvents was solved, enabling the preparation of high-performance fibers, reducing production costs, and improving the strength and surface quality of cellulose fibers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GANNAN NORMAL UNIV
- Filing Date
- 2023-03-24
- Publication Date
- 2026-08-04
AI Technical Summary
In existing technologies, natural polymer solvents are difficult to recover and process, resulting in high production costs and poor fiber performance.
Low-cost, green, non-toxic and harmless inorganic salt solutions, including bicarbonate, carbonate, bisulfite and sulfite, are used as coagulation baths. Cellulose fibers are prepared by wet spinning in combination with urea and thiourea auxiliaries. The reaction of bicarbonate with strong alkali generates easily separable salts, thereby achieving uniform coagulation and stretching of the fibers.
The resulting high-performance fibers have a circular cross-section, smooth surface, and are soft and lustrous, which reduces the difficulty and cost of salt recycling and improves the strength and quality of the fibers.
Smart Images
Figure CN116163025B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of natural polymer solution coagulation molding technology, specifically to a solution coagulation molding method containing natural polymers and a long fiber spinning method. Background Technology
[0002] Natural polymers mainly include cellulose, chitin, and chitosan. These polymers exhibit extremely strong hydrogen bonds both between and within molecules, making them insoluble in common solvents and difficult to utilize directly. Currently, solvents used to dissolve natural polymers include NaOH / CS2, LiCl / DMAc, ionic liquids, N-methylmorpholine-N-oxide, and alkali / urea aqueous solvent systems. Alkaline solutions are currently a promising solvent system for natural polymers, such as sodium hydroxide, sodium hydroxide / urea aqueous solution, lithium hydroxide / urea, and potassium hydroxide / urea. The natural polymer solution is then solidified in an acidic coagulation bath. Coagulation is a crucial step in the precipitation of the spinning solution from a homogeneous stream. The composition of the coagulation bath directly affects and determines product performance and cost, and also needs to consider the separation and recovery of salts and the treatment of waste after the reaction with the solvent.
[0003] Patent application 200410013389.X discloses a method for preparing regenerated cellulose fibers. The method involves dissolving cellulose in a mixed aqueous solution of 5-12 wt% sodium hydroxide and 8-20 wt% urea, stirring thoroughly to obtain a concentrated cellulose solution. Natural polymers mainly include cellulose, chitin, and chitosan. These natural polymers exhibit extremely strong hydrogen bonding both between and within molecules, making them insoluble in common solvents and difficult to utilize directly. Currently, solvents used for dissolving natural polymers mainly include NaOH / CS2, LiCl / DMAc, ionic liquids, N-methylmorpholine-N-oxide, and alkali / urea aqueous solvent systems. Alkaline solutions are currently a promising natural polymer solvent system, such as sodium hydroxide, sodium hydroxide / urea solution, lithium hydroxide / urea, and potassium hydroxide / urea. The natural polymer solution is then solidified in an acidic coagulation bath. Coagulation is a crucial step in the precipitation of spinning solution from a homogeneous fine stream. The composition of the coagulation bath not only directly affects and determines product performance and cost, but also needs to consider the issues of salt separation and recovery and waste treatment after its reaction with the solvent.
[0004] Patent application 200410013389.X discloses a method for preparing regenerated cellulose fibers. Cellulose is dissolved in a mixed aqueous solution of 5-12 wt% sodium hydroxide and 8-20 wt% urea, stirred thoroughly to obtain a concentrated cellulose solution, and then spun into fibers using a wet spinning method on a spinning machine, followed by regeneration and coagulation in a coagulation bath. The coagulation bath is composed of a 3-25 wt% sulfuric acid aqueous solution, a 3-25 wt% sulfuric acid / 5-30 wt% sodium sulfate aqueous solution, or a 3-25 wt% sulfuric acid / 5-30 wt% ammonium sulfate aqueous solution, etc. Patent application 200510018799.8 discloses a two-step coagulation bath method for preparing regenerated cellulose fibers, in which the coagulation bath is composed of a mixed aqueous solution of 5-20 wt% sulfuric acid and 10-25 wt% sodium sulfate. CN103757720A discloses a coagulation bath for cellulose solution spinning using an alkali / urea / water solvent system. The first and second coagulation baths are aqueous solutions containing phosphoric acid and / or phosphates, resulting in thorough coagulation of the cellulose fibers. The prepared fibers have a circular interface, are soft, and have high strength. CN110042488A discloses a sodium hydroxide / urea / zinc oxide solvent system. Spinning and coagulation are performed in a mixed solution of citric acid, sodium citrate, ethylene glycol, and water (5–35 wt%, 2–20 wt%, 5–60 wt%, and 10–70 wt%). After preliminary stretching and orientation, washing, and drying, high-strength regenerated cellulose filaments are obtained. The coagulation baths composed of strong or weak acids react with alkali / urea streams to generate multiple salts or mixed aqueous solutions of multiple salts and urea, which are difficult to separate. This makes the recycling of solvents or salts difficult, directly increasing the difficulty and cost of salt separation and recovery, as well as waste treatment. CN107653502A uses phytic acid as a coagulation bath to prepare high-strength fiber filaments based on nanofibers. However, phytic acid is expensive, which greatly increases the production cost. CN102443869A discloses a method for coagulating and forming a cellulose solution, (1) dissolving cellulose pulp in a mixed aqueous solution of urea or thiourea, alkali metal hydroxide, and the above to obtain a cellulose solution; (2) solidifying the cellulose solution in step (1) in a non-acidic first coagulation bath at a temperature of 50-100°C, wherein the concentrations of urea / thiourea and alkali metal hydroxide are lower than the concentrations used for the corresponding components in step (1); (3) obtaining cellulose fibers after subsequent processing. However, the coagulation speed is slow, the reaction is incomplete, and high-temperature coagulation leads to phase separation and low strength in the fibers. Summary of the Invention
[0005] To address the problems of poor product performance and high costs of recycling and processing coagulated bath salts in existing technologies, this invention provides a solution coagulation molding method and spinning method containing natural polymers. Using the coagulation molding method described in this invention, low-cost, green, efficient, non-toxic, harmless, and inexpensive inorganic salt solutions are used. These solutions do not contain strong acids or organic solvents and can produce fibers with a circular cross-section and excellent mechanical properties. Furthermore, the fibers have a smooth, soft, and glossy surface.
[0006] The first aspect of the present invention provides a method for solidifying and molding a solution containing natural polymers, wherein a fiber stream obtained by wet spinning a solution containing natural polymers is formed by passing it through at least one solidification bath, wherein the solution containing natural polymers contains metal hydroxides and auxiliaries, and the auxiliaries are selected from at least one of urea, zinc oxide and thiourea.
[0007] The coagulation bath is a first coagulation bath, containing XHCO3 and / or XHSO3; wherein X is selected from at least one of Li, Na, K, Rb, Cs, Fr, and NH4; the mass concentration of XHCO3 and / or XHSO3 in the coagulation bath is 0.5-30 wt%; or
[0008] The coagulation bath is a second coagulation bath, which contains XHCO3 and Y2CO3, or XHSO3 and Y2SO3; wherein Y is selected from at least one of Li, Na, K, Rb, Cs, Fr and NH4; the mass concentration of XHCO3 or XHSO3 is 0.5-30 wt% each; and the mass concentration of Y2CO3 or Y2SO3 is 0.5-30 wt% each.
[0009] A second aspect of the present invention provides a method for spinning long fibers, the method comprising:
[0010] Nascent fibers are obtained by the coagulation molding method described in this invention, and the nascent fibers are then washed, oiled, and dried to obtain long fibers.
[0011] Compared with the prior art, the coagulation and molding method of the solution containing natural polymers described in this invention uses bicarbonate or a combination of bicarbonate and carbonate, or bisulfite or bisulfite and sulfite as components of the coagulation bath. As a mild coagulation solution, it is beneficial for the uniform coagulation and molding of the fiber filaments formed by the solution containing natural polymers described in this invention. In this process, the fiber filaments have not yet fully formed the intermolecular hydrogen bond network of cellulose, which is conducive to full solidification and stretching in the coagulation bath and subsequent stretching, thereby obtaining fibers with a circular cross-section and excellent performance (strength up to 2.4 cN / dtex). Furthermore, the fiber surface is smooth, the fiber is soft and shiny, the cross-section is dense, the structure is uniform, and there is no obvious core-sheath structure.
[0012] In the coagulation bath described in this invention, the main component of the salt solution is weakly alkaline bicarbonate. This salt reacts with a strong alkali. The accumulation of urea and / or thiourea as additives in the coagulation bath is beneficial to improving product performance. When the additive is a metal salt (e.g., zinc oxide), a corresponding precipitate is generated in the coagulation bath, which can be filtered out without affecting the regeneration of weakly acidic bicarbonate or bisulfite. It is regenerated into bicarbonate or bisulfite through carbon dioxide or sulfation. Therefore, urea and / or thiourea can be recycled. Furthermore, bicarbonate, carbonate, bisulfite, and sulfite are easily separated and recovered, making the consumption of chemical materials comparable to or even lower than that of adhesive processes. This solves the problem of recycling and processing high-concentration salts, reduces production difficulty and costs, and has broad application prospects. Attached Figure Description
[0013] Figure 1 The image shown is a scanning electron microscope (SEM) image of the long fiber prepared in Example 1.
[0014] Figure 2 The image shown is a scanning electron microscope (SEM) image of the long fiber prepared in Example 1.
[0015] Figure 3 The image is a scanning electron microscope (SEM) image of the long fiber prepared for Comparative Example 1.
[0016] Figure 4 The image shown is a scanning electron microscope (SEM) image of the long fiber prepared for Comparative Example 1. Detailed Implementation
[0017] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0018] The first aspect of the present invention provides a method for solidifying and molding a solution containing natural polymers, wherein a fiber stream obtained by wet spinning a solution containing natural polymers is formed by passing it through at least one solidification bath, wherein the solution containing natural polymers contains metal hydroxides and auxiliaries, and the auxiliaries are selected from at least one of urea, zinc oxide and thiourea.
[0019] The coagulation bath is a first coagulation bath, containing XHCO3 and / or XHSO3; wherein X is selected from at least one of Li, Na, K, Rb, Cs, Fr, and NH4; the mass concentration of XHCO3 and / or XHSO3 in the coagulation bath is 0.5-30 wt%; or
[0020] The coagulation bath is a second coagulation bath, which contains XHCO3 and Y2CO3, or XHSO3 and Y2SO3; wherein Y is selected from at least one of Li, Na, K, Rb, Cs, Fr and NH4; the mass concentration of XHCO3 or XHSO3 is 0.5-30 wt% each; and the mass concentration of Y2CO3 or Y2SO3 is 0.5-30 wt% each.
[0021] The coagulation and molding method of the solution containing natural polymers described in this invention uses bicarbonate or a combination of bicarbonate and carbonate, or bisulfite or bisulfite and sulfite as coagulation bath components. As a mild coagulation solution, it is beneficial for the uniform coagulation and molding of the fiber filaments formed by the solution containing natural polymers described in this invention. During this process, the fiber filaments have not yet fully formed the intermolecular hydrogen bond network of cellulose, which is conducive to full solidification and stretching in the coagulation bath and subsequent stretching, thereby obtaining fibers with a circular cross-section and excellent performance (strength up to 2.4 cN / dtex). Furthermore, the fiber surface is smooth, the fiber is soft and lustrous, the cross-section is dense, the structure is uniform, and there is no obvious core-sheath structure.
[0022] In this invention, the range of selectable molding conditions is relatively wide. According to a preferred embodiment of this invention, the molding conditions include a temperature of 10-80℃, preferably 20-40℃.
[0023] In this invention, the additives urea and / or thiourea accumulate in the coagulation bath to improve product performance. According to a preferred embodiment of the invention, the coagulation bath further contains urea and / or thiourea. Preferably, the mass concentration of urea and / or thiourea is 5-60 wt%, for example, the mass concentration of urea and / or thiourea is 10 wt%, 15 wt%, 18 wt%, 20 wt%, 25 wt%, 28 wt%, 30 wt%, 32 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, or 45 wt%.
[0024] In this invention, the mass concentration of the natural polymer material in the solution containing the natural polymer has a wide range of selectable values. According to a preferred embodiment of this invention, the mass concentration of the natural polymer material in the solution containing the natural polymer is 5wt%-9wt%; preferably, the degree of polymerization of the natural polymer material is 200-800.
[0025] In this invention, the mass concentration of the auxiliary agent in the solution containing natural polymers can be selected over a wide range. According to a preferred embodiment of this invention, the mass concentration of the auxiliary agent in the solution containing natural polymers is 0.01wt%-15wt%.
[0026] In this invention, the range of types of natural polymer materials that can be selected is relatively wide. According to a preferred embodiment of this invention, the natural polymer material is selected from at least one of cellulose, chitin, chitosan and sodium alginate.
[0027] According to a preferred embodiment of the present invention, the metal hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.
[0028] In this invention, the fiber stream passes through at least one coagulation bath, for example, it can be coagulated and formed through one, two, three, or four coagulation baths. According to a preferred embodiment of this invention, the fiber stream passes through two coagulation baths, which is beneficial to improving the performance of the fiber.
[0029] According to a preferred embodiment of the present invention, in the first coagulation bath, when the coagulation bath is the first coagulation bath, the mass concentration of XHCO3 or XHSO3 is 0.5-30wt%.
[0030] When the coagulation bath is a second coagulation bath, the mass concentration of XHCO3 or XHSO3 is 0.5-30 wt% each; the mass concentration of Y2CO3 or Y2SO3 is 0.5-30 wt% each.
[0031] According to a preferred embodiment of the present invention, in the second coagulation bath, when the coagulation bath is the first coagulation bath, the mass concentration of XHCO3 or XHSO3 is 5-15wt%.
[0032] When the coagulation bath is a second coagulation bath, the mass concentration of XHCO3 or XHSO3 is 5-15 wt%; the mass concentration of Y2CO3 or Y2SO3 is 1-10 wt%.
[0033] According to a preferred embodiment of the present invention, in the first coagulation bath,
[0034] When the coagulation bath is the first coagulation bath, the mass concentration of XHCO3 or XHSO3 is 8-20wt% respectively.
[0035] When the coagulation bath is a second coagulation bath, the mass concentration of XHCO3 or XHSO3 is 8-20 wt% and the mass concentration of Y2CO3 or Y2SO3 is 2-6 wt% respectively.
[0036] According to a preferred embodiment of the present invention, in the first coagulation bath, the coagulation bath is a second coagulation bath, wherein the mass concentration of XHCO3 or XHSO3 is 8-15wt% each; the mass concentration of Y2CO3 or Y2SO3 is 2-6wt% each; and the mass concentration of urea and / or thiourea is 20-40wt%.
[0037] According to a preferred embodiment of the present invention, the solidification molding method further includes stretching the molded fibers, with a stretching rate of -50% to 100%.
[0038] According to a preferred embodiment of the present invention, the draw ratio of the first coagulation bath is -50% to 100%, and the draw ratio of the second coagulation bath is 0-100%.
[0039] According to a preferred embodiment of the present invention, the molding temperature in the first coagulation bath is 20-40°C; and the molding temperature in the second coagulation bath is 40-60°C.
[0040] A second aspect of the present invention provides a method for spinning long fibers, the method comprising:
[0041] Nascent fibers are obtained by the coagulation molding method described in this invention, and the nascent fibers are then washed, oiled, and dried to obtain long fibers.
[0042] In this invention, long fibers refer to continuous filaments from fiber processing that have not undergone a cutting process.
[0043] In this invention, there are no particular limitations on the washing conditions; it is sufficient to wash away the salt.
[0044] In this invention, oiling is used to improve softness; for example, silicone oil can be applied to the nascent fibers obtained after washing.
[0045] In this invention, there are no particular limitations on the drying conditions. Preferably, the drying conditions include a temperature of 80-130°C and a time of 2-5 hours.
[0046] The present invention will be further illustrated by the following embodiments, but these embodiments in no way limit the scope of the present invention.
[0047] In the following examples, the density, elongation, and average strength of the regenerated fibers were tested according to the bamboo pulp viscose filament standard (FZ-T 54012-2007).
[0048] Example 1
[0049] (i) Dissolve cellulose with a DP of 400 in a sodium hydroxide / urea / water system (mass ratio of 7:12:81), and filter and degas to obtain a solution containing 7.5 wt% cellulose;
[0050] (ii) The solution in step (i) is wet-spun to obtain a fiber stream, which is then passed through a coagulation bath containing 14 wt% sodium bicarbonate and 2 wt% sodium carbonate (the temperature of the coagulation bath is 50°C) and subjected to 30% positive stretching to obtain nascent fibers.
[0051] (iii) The nascent fibers are sequentially washed with hot water at 65°C, oiled (with silicone oil), and dried at 110°C to obtain regenerated cellulose long fibers. The regenerated cellulose long fibers have a linear density of 133 dtex, a dry elongation of 12.1%, and an average strength of 1.7 cN / dtex.
[0052] The long-fiber scanning electron microscope (SEM) image is shown below. Figure 1 , Figure 2 As shown, the fiber has a circular cross-section, a smooth surface, a dense cross-section, a uniform structure, and no obvious skin-core structure.
[0053] Example 2
[0054] (i) Dissolve cellulose with a DP of 250 in a sodium hydroxide / urea / water system (mass ratio of 7:5:87) and degas to obtain a solution containing 8 wt% cellulose;
[0055] (ii) The solution in step (i) is wet-spun to obtain a fiber stream, which is then passed through a coagulation bath containing 15 wt% sodium bisulfite and 15 wt% sodium sulfite (the temperature of the coagulation bath is 20°C) and subjected to 30% positive stretching to obtain nascent fibers.
[0056] (iii) The nascent fibers are sequentially washed with water at 65°C, oiled (with silicone oil), and dried at 130°C to obtain regenerated cellulose long fibers. The regenerated cellulose long fibers have a linear density of 133 dtex, a dry elongation of 15.6%, and an average strength of 1.9 cN / dtex.
[0057] Example 3
[0058] The method of Preparation Example 1 is the same, except that in step (ii), the composition of the coagulation bath is: 9 wt% sodium bicarbonate, 2 wt% sodium carbonate, and 20 wt% urea (the temperature of the coagulation bath is 20°C); the other conditions are the same as in Preparation Example 1.
[0059] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 16%, and an average strength of 2.2 cN / dtex.
[0060] Example 4
[0061] (i) Chitin with a DP of 250 was dissolved in a potassium hydroxide / urea / water system (mass ratio of 12.7:5.7:81.6) and degassed to obtain a solution containing 7 wt% chitin;
[0062] (ii) The solution in step (i) is wet-spun to obtain a fiber stream. The fiber stream passes through a coagulation bath (the temperature of the coagulation bath is 10°C) containing 20 wt% potassium bicarbonate, 15 wt% potassium carbonate and 30 wt% urea, and is subjected to 20% positive stretching to obtain nascent fibers.
[0063] (iii) The nascent fibers are sequentially washed with water at 65°C, oiled (with silicone oil), and dried at 130°C to obtain regenerated chitin fibers. The regenerated chitin fibers have a dry elongation of 12.3% and an average strength of 1.7 cN / dtex.
[0064] Example 5
[0065] (i) Dissolve cellulose with a DP of 400 in a sodium hydroxide / urea / water system (mass ratio of 7:12:81) and degas to obtain a solution containing 7.5 wt% cellulose;
[0066] (ii) The solution in step (i) is wet-spun to obtain a fiber stream, which is passed through a first coagulation bath (containing 8 wt% sodium bicarbonate and 2 wt% sodium carbonate) at a temperature of 20°C and subjected to 30% positive drawing.
[0067] Then it goes through a second coagulation bath (containing 5 wt% sodium bicarbonate and 2 wt% sodium carbonate), the temperature of the coagulation bath is 50°C, and it is subjected to 50% positive stretching;
[0068] (iii) The nascent fibers are washed with hot water at 65°C, oiled (with silicone oil), and dried at 110°C to obtain regenerated cellulose long fibers.
[0069] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 16.0%, and an average strength of 2.2 cN / dtex.
[0070] Example 6
[0071] (i) Dissolve cellulose with a DP of 400 in a sodium hydroxide / urea / water system (mass ratio of 7:12:81) and degas to obtain a solution containing 7.5 wt% cellulose;
[0072] (ii) The solution in step (i) is wet-spun to obtain a fiber stream, which is passed through a first coagulation bath (8 wt% sodium bicarbonate, 2 wt% sodium carbonate, 20 wt% urea) at a temperature of 20°C and subjected to 30% positive drawing.
[0073] Then it goes through a second coagulation bath (containing 5 wt% sodium bicarbonate and 2 wt% sodium carbonate), the temperature of the coagulation bath is 50°C, and it is subjected to 50% positive stretching;
[0074] (iii) The nascent fibers are washed with hot water at 65°C, oiled (with silicone oil), and dried at 110°C to obtain regenerated cellulose long fibers.
[0075] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 16.1%, and an average strength of 2.4 cN / dtex.
[0076] Example 7
[0077] The method of Preparation Example 1 is the same, except that in step (2), the composition of the coagulation bath is: 16 wt% sodium bicarbonate (the temperature of the coagulation bath is 60 °C); the other conditions are the same as those of Preparation Example 1.
[0078] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 12.2%, and an average strength of 1.7 cN / dtex.
[0079] Example 8
[0080] (i) Dissolve cellulose with a DP of 400 in a sodium hydroxide / urea / water system (mass ratio of 7:12:81) and degas to obtain a solution containing 7.5 wt% cellulose;
[0081] (ii) The solution in step (1) is wet-spun to obtain a fiber stream, which is passed through a first coagulation bath (containing 7 wt% sodium bicarbonate and 1 wt% sodium carbonate) at a temperature of 20°C and subjected to 20% positive drawing.
[0082] Then it goes through a second coagulation bath (containing 5 wt% sodium bicarbonate and 2 wt% sodium carbonate), the temperature of the coagulation bath is 50°C, and it is subjected to 30% positive stretching;
[0083] (iii) The nascent fibers are washed with hot water at 65°C, oiled (with silicone oil), and dried at 110°C to obtain regenerated cellulose long fibers.
[0084] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 15.2%, and an average strength of 1.9 cN / dtex.
[0085] Comparative Example 1
[0086] The method is the same as in Example 1, except that the coagulation bath is a sulfuric acid coagulation bath system (specifically composed of 110 g / L sulfuric acid and 150 g / L sodium sulfate), and the other conditions are the same as in Example 1.
[0087] The regenerated fiber has a linear density of 133 dtex, a dry elongation of 8.0%, and an average strength of 1.1 cN / dtex.
[0088] The scanning electron microscope (SEM) image of the regenerated fibers is shown below. Figure 3 , Figure 4 As shown, the fiber has an irregular cross-section, numerous surface wrinkles, and a large number of irregular pores, exhibiting a distinct skin-core structure.
[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for spinning long fibers, characterized in that, The method includes: wet spinning a fiber stream obtained from a solution containing natural polymers and then passing it through two coagulation baths to form nascent fibers; the nascent fibers are then washed, oiled, and dried to obtain long fibers; the solution containing natural polymers contains metal hydroxides and auxiliaries, the auxiliaries being selected from urea and / or thiourea; The coagulation bath is a first coagulation bath, which is a solution containing XHCO3 and / or XHSO3 as solute, and urea and / or thiourea; wherein X is selected from at least one of Li, Na, K, Rb, Cs, Fr, and NH4; or The coagulation bath is a second coagulation bath, which is a solution of solutes XHCO3 and Y2CO3, or XHSO3 and Y2SO3, and urea and / or thiourea; wherein Y is selected from at least one of Li, Na, K, Rb, Cs, Fr and NH4; In the first coagulation bath, which is the second coagulation bath, the mass concentration of XHCO3 or XHSO3 is 8-15 wt% each; the mass concentration of Y2CO3 or Y2SO3 is 2-6 wt% each; and the mass concentration of urea and / or thiourea is 20-40 wt%. In the second coagulation bath, when the coagulation bath is the first coagulation bath, the mass concentration of XHCO3 or XHSO3 is 5-15 wt%. When the coagulation bath is a second coagulation bath, the mass concentration of XHCO3 or XHSO3 is 5-15 wt%; the mass concentration of Y2CO3 or Y2SO3 is 1-10 wt%. In the solution containing natural polymers, the mass concentration of the natural polymer material is 5wt%-9wt%; the mass concentration of the additives is 0.01wt%-15wt%; and the natural polymer material is selected from at least one of cellulose, chitin, chitosan and sodium alginate.
2. The long fiber spinning method according to claim 1, wherein, Molding conditions include a temperature of 10-80℃.
3. The long fiber spinning method according to claim 1 or 2, wherein, Molding conditions include: a temperature of 20-40℃; and / or The degree of polymerization of the natural polymer material is 200-800.
4. The long fiber spinning method according to claim 1 or 2, wherein, The metal hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.
5. The long fiber spinning method according to claim 1 or 2, wherein, The long fiber spinning method also includes stretching the shaped fibers, with a stretching rate of -50% to 100%.
6. The long fiber spinning method according to claim 1, wherein, The draw ratio of the first coagulation bath is -50% to 100%, and the draw ratio of the second coagulation bath is 0 to 100%.