A method for preparing ion-conductive viscose fiber

Abstract

This invention discloses a method for preparing ion-conductive viscose fiber, including preparing a viscose spinning solution, viscose spinning, and post-treatment of the viscose fiber. The post-treatment of the viscose fiber includes the following steps: feeding the viscose staple fiber obtained in the viscose spinning step into a refining mill, and sequentially performing a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling, and drying processes to obtain ion-conductive viscose fiber. This invention optimizes the viscose fiber forming process and post-treatment steps. During the fiber forming process, the amounts of sulfuric acid, zinc sulfate, and sodium sulfate in the coagulation bath are optimized; a higher amount of sodium hypochlorite is added in the bleaching process; and a higher amount of hydrogen peroxide and an appropriate amount of waterborne polyurethane are added in the oiling process. This results in ion-conductive viscose fiber with high ion conductivity. Using this ion-conductive viscose fiber to make a battery separator helps reduce battery internal resistance and improve charge and discharge efficiency.

Description

Technical Field

[0001] This invention relates to the field of chemical fiber processing technology, and in particular to a method for preparing ion-conductive viscose fiber. Background Technology

[0002] In recent years, with the popularization of new energy vehicles and smartphones, the requirements for battery performance have become increasingly stringent, and the application of battery-specific fibers in battery materials has become more and more widespread. They can be used as battery separators, conductive materials, and electrodes. Cellulose-based materials, with their advantages of abundant raw material sources, low cost, and environmental safety, have become an important research direction.

[0003] Patent application CN2016100760032 discloses a method for preparing a viscose fiber-nano silica composite separator. In this method, viscose fiber, as the main separator material, not only avoids the problem of lithium dendrites easily piercing polymer separators and causing battery short circuits, but also endows the separator with good shape retention and dimensional stability due to its inherent advantages. Furthermore, the addition of nano silica further improves the separator's strength and porosity, enhancing its wettability and retention capacity with the electrolyte. Simultaneously, silica can react with trace amounts of hydrofluoric acid in the electrolyte, thereby improving the cycle performance, rate performance, and low-temperature performance of the lithium battery. The research paper "Study on the Regulation of Zinc Deposition Behavior of AZIBs by Viscose Fiber and Nano-Chitosan Separator" mentions that surface grooves on viscose fibers can significantly accelerate the horizontal transport rate of zinc ions on the negative electrode surface, and the ionic conductivity was measured using a viscose separator. However, neither the above patent application nor the research paper mentions how to prepare viscose fibers with high ionic conductivity.

[0004] The ionic conductivity of a battery separator is a key performance indicator measuring its ability to conduct ions within the battery, significantly impacting overall battery performance. Existing viscose fibers used in zinc-ion battery separators exhibit relatively low ionic conductivity. Therefore, providing a method for preparing ion-conducting cellulose fibers has become an urgent priority. Summary of the Invention

[0005] In view of this, this application provides a method for preparing ion-conductive viscose fiber. This method optimizes the viscose fiber forming process and post-processing steps. During the fiber forming process, the dosage of sulfuric acid, zinc sulfate, and sodium sulfate in the coagulation bath is optimized. A higher dosage of sodium hypochlorite is added in the bleaching process. A higher dosage of hydrogen peroxide and an appropriate amount of waterborne polyurethane are added in the oiling process. This results in ion-conductive viscose fiber with high ion conductivity. Using this ion-conductive viscose fiber to make a battery separator helps to reduce the battery's internal resistance and improve charge and discharge efficiency.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] A method for preparing ion-conductive viscose fiber includes the following steps: preparing viscose spinning solution, viscose spinning, and post-treatment of viscose fiber;

[0008] The preparation of viscose spinning dope includes the following steps: selecting softwood dissolving pulp and hardwood dissolving pulp with whiteness ≥89% and methyl cellulose content ≥90%; firstly, mixing the softwood dissolving pulp and hardwood dissolving pulp at a mass ratio of 4-5:100; then preparing viscose spinning dope through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps;

[0009] The viscose spinning process includes the following steps: the viscose spinning solution is fed into a spinning machine and ejected from the spinneret by a metering pump. It reacts with a coagulation bath in an acid bath, coagulating to regenerate nascent fibers. The coagulated and regenerated nascent fibers are then stretched and oriented to form fibers with a certain strength. After being cut, the fibers enter a pile tank, where steam bubbles ejected from small holes in the bottom of the pile tank disperse the fibers, resulting in a uniform fiber layer thickness. The coagulation bath contains 100–108 g / L of sulfuric acid, 8–10 g / L of zinc sulfate, and 325–350 g / L of sodium sulfate.

[0010] The post-processing of the viscose fiber includes the following steps: the viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying processes to obtain ion-conductive viscose fiber.

[0011] The bleaching process uses a bleaching solution; the bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.2-2.5 g / L.

[0012] The oiling process involves applying an oil bath to the viscose staple fiber. The oil bath is made by mixing hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath is 0.9–1.1 g / L, and the concentration of waterborne polyurethane in the oil bath is 0.1–0.2 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane.

[0013] In the preparation method of ion-conductive viscose fiber of this application, by optimizing the viscose fiber forming process and post-processing steps, the dosage of sulfuric acid, zinc sulfate and sodium sulfate in the coagulation bath is optimized during the fiber forming process, a higher dosage of sodium hypochlorite is added in the bleaching process, and a higher dosage of hydrogen peroxide and an appropriate amount of waterborne polyurethane are added in the oiling process, so that the obtained ion-conductive viscose fiber has a high ion conductivity. Using the ion-conductive viscose fiber to make a battery separator is beneficial to reducing the internal resistance of the battery and improving the charging and discharging efficiency. Specifically, optimizing the fiber forming conditions involves using a higher concentration of sulfuric acid and a lower concentration of zinc sulfate in the coagulation bath, which is beneficial for viscose fibers to form a thin-skin core structure. In the bleaching process, adding a higher concentration of sodium hypochlorite is beneficial for enhancing the oxidizing effect of the bleaching agent. In the oiling process, adding 0.1–0.2 g / L of waterborne polyurethane to the oil bath allows the waterborne polyurethane to react with the hydroxyl groups on the fiber at high temperatures, causing the polyurethane itself to undergo a cross-linking reaction. This forms a three-dimensional network structure of polymer film covering the fiber surface, promoting the spontaneous rise of liquid along the capillary pores or grooves between the fibers. This facilitates faster liquid transport in the fiber grooves and channels, thereby improving the ionic conductivity of the fiber.

[0014] Specifically, in the viscose spinning step, a polyether defoamer is added to the fluffing trough at a rate of 2.0–2.5 kg / h; the inlet steam pressure of the fluffing trough is 1.2–1.3 bar; and the spinning speed of the spinning machine is 59–69 m / min.

[0015] This application eliminates foam by adding a defoamer to the pile groove, and facilitates the escape of a large amount of sulfide gases such as hydrogen sulfide and carbon disulfide, which is beneficial to the formation of a porous structure inside the fiber.

[0016] Specifically, in the viscose fiber post-treatment step, the desulfurization process involves using a desulfurizing agent at 85-86°C to desulfurize the viscose staple fiber. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide in the desulfurizing agent being 1-2 g / L and the concentration of sodium hydroxide being 3.0-3.3 g / L.

[0017] Adding an appropriate concentration of sodium sulfide to the desulfurization process can enhance the desulfurization effect.

[0018] Specifically, in the viscose fiber post-treatment step, the temperature of the bleaching solution is 50-55℃ and the pH is 9-10, and the bleaching time of the viscose staple fiber is 3-3.5 minutes.

[0019] Specifically, in the viscose fiber post-treatment step, the temperature of the oil bath is 70-75°C, and the pH value of the oil bath is adjusted to 3-4 using sulfuric acid.

[0020] Specifically, in the viscose fiber post-treatment step, the first washing temperature is 70-75℃, and the first washing volume is 60-70 mg / L. 3 / h, the second water washing temperature is 60-68℃, and the second water washing volume is 30-40m³ / h. 3 / h, the temperature of the three-water wash is 40-55℃, and the washing volume is 35-45m³ / h. 3 / h, the final water washing temperature is 70-75℃, and the final water washing volume is 70-80m³ / h. 3 / h.

[0021] Specifically, in the viscose fiber post-treatment step, the drying temperature is 135-145℃.

[0022] The preferred drying temperature is beneficial for removing moisture and other volatiles from the viscose fiber finished product.

[0023] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.11~1.75dtex; length 38~40mm; dry breaking strength ≥2.10cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5mg / 100g; residual sulfur content ≤4mg / 100g; whiteness ≥87.5%; ionic conductivity ≥5.0mS / cm.

[0024] As can be seen from the above technical solution, this application has at least the following advantages and positive effects:

[0025] (1) In the preparation method of the ion-conductive viscose fiber of the present invention, by optimizing the viscose fiber forming process and post-processing steps, the amount of sulfuric acid, zinc sulfate and sodium sulfate in the coagulation bath is optimized during the fiber forming process, a higher amount of sodium hypochlorite is added in the bleaching process, a higher amount of hydrogen peroxide and an appropriate amount of waterborne polyurethane are added in the oiling process, so that the obtained ion-conductive viscose fiber has a higher ion conductivity. The battery separator made using the ion-conductive viscose fiber is beneficial to reduce the internal resistance of the battery and improve the charging and discharging efficiency.

[0026] (2) By optimizing the fiber forming conditions, the present invention uses a higher concentration of sulfuric acid and a lower concentration of zinc sulfate in the coagulation bath, which is conducive to the formation of a thin skin core structure of viscose fiber.

[0027] (3) This invention improves the oxidation effect of sodium hypochlorite and hydrogen peroxide by optimizing the sodium hypochlorite bleaching and oiling process, thereby increasing the carboxyl content on the fiber surface. Detailed Implementation

[0028] The exemplary embodiments of the present invention are described in more detail below. These embodiments are intended to provide a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. While exemplary embodiments of the present invention are shown, it should be understood that the invention should not be limited to the embodiments set forth herein.

[0029] The method for testing the ionic conductivity of this invention is as follows: Referring to the literature "Study on the regulation of zinc deposition behavior of AZIBs by viscose fiber and nano-chitosan membrane", 13±1mg of fiber was spread on a 16mm diameter disc, and 2mol / L zinc sulfate solution was used as the electrolyte. The battery assembled from the fiber sample was subjected to electrochemical impedance spectroscopy to obtain the sample resistance and calculate the ionic conductivity.

[0030] Example 1

[0031] Prepare ion-conductive viscose fibers according to the following steps:

[0032] (1) Preparation of viscose spinning solution

[0033] Softwood dissolving pulp with a whiteness of 90% and a fiber content of 91% and hardwood dissolving pulp with a whiteness of 89% and a fiber content of 90% are selected. First, the softwood dissolving pulp and hardwood dissolving pulp are mixed at a mass ratio of 4:100. Then, viscose spinning dope is prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0034] (2) Viscose spinning

[0035] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0036] The coagulation bath contains 100 g / L sulfuric acid, 8 g / L zinc sulfate, and 325 g / L sodium sulfate;

[0037] A polyether-based defoamer is added to the fluffing tank at a rate of 2.0 kg / h, and the inlet steam pressure of the fluffing tank is 1.2 bar.

[0038] The spinning speed of the spinning machine is 59 m / min;

[0039] (3) Post-treatment of viscose fibers

[0040] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0041] The first wash temperature is 70℃, and the first wash volume is 60m³. 3 / h, the second water wash temperature is 60℃, and the second water wash volume is 30m³. 3 / h, the three-water washing temperature is 40℃, and the three-water washing volume is 35m³ / h. 3 / h, the final water wash temperature is 70℃, and the final water wash volume is 70m³ / h. 3 / h;

[0042] The desulfurization process involves using a desulfurizing agent at 85°C to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1 g / L and the concentration of sodium hydroxide being 3.0 g / L.

[0043] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 50℃ and the pH is 9. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.2g / L; the viscose staple fiber undergoes the bleaching process for 3.5 minutes.

[0044] The oiling process involves applying an oil bath solution at 70°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 0.9 g / L, and the concentration of waterborne polyurethane in the oil bath solution is 0.1 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 3 using sulfuric acid.

[0045] The drying temperature is 135°C.

[0046] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.75 dtex; length 40 mm; dry breaking strength ≥ 2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤ 1.5 mg / 100g; residual sulfur content ≤ 4 mg / 100g; whiteness 87.5%; ionic conductivity 5.0 mS / cm.

[0047] Example 2

[0048] Prepare ion-conductive viscose fibers according to the following steps:

[0049] (1) Preparation of viscose spinning solution

[0050] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 89% and a methyl cellulose content of 90% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 5:100. Then, viscose spinning dope was prepared by impregnation, pressing, crushing, aging, xanthation, dissolving and maturation.

[0051] (2) Viscose spinning

[0052] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0053] The coagulation bath contains 108 g / L of sulfuric acid, 10 g / L of zinc sulfate, and 350 g / L of sodium sulfate;

[0054] A polyether-based defoamer is added to the fluffing tank at a rate of 2.5 kg / h, and the inlet steam pressure of the fluffing tank is 1.3 bar.

[0055] The spinning speed of the spinning machine is 69 m / min;

[0056] (3) Post-treatment of viscose fibers

[0057] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0058] The first wash temperature is 75℃, and the first wash volume is 70m³. 3 / h, the second water wash temperature is 68℃, and the second water wash volume is 40m³ / h. 3 / h, the three-water washing temperature is 55℃, and the three-water washing volume is 45m³ / h. 3 / h, the final water wash temperature is 75℃, and the final water wash volume is 80m³ / h. 3 / h;

[0059] The desulfurization process involves using a desulfurizing agent at 86°C to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 2 g / L and the concentration of sodium hydroxide being 3.3 g / L.

[0060] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 55℃ and the pH is 10. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.5g / L; the viscose staple fiber undergoes the bleaching process for 3 minutes.

[0061] The oiling process involves applying an oil bath solution at 75°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 1.1 g / L, and the concentration of waterborne polyurethane in the oil bath solution is 0.2 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 4 using sulfuric acid.

[0062] The drying temperature is 145°C.

[0063] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.32 dtex; length 38 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.5%; ionic conductivity 7.7 mS / cm.

[0064] Example 3

[0065] Prepare ion-conductive viscose fibers according to the following steps:

[0066] (1) Preparation of viscose spinning solution

[0067] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 90% and a methyl cellulose content of 91% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 4.5:100. Then, viscose spinning dope was prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0068] (2) Viscose spinning

[0069] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0070] The coagulation bath contains 105 g / L of sulfuric acid, 9 g / L of zinc sulfate, and 340 g / L of sodium sulfate;

[0071] A polyether-based defoamer is added to the fluffing tank at a rate of 2.2 kg / h, and the inlet steam pressure of the fluffing tank is 1.25 bar.

[0072] The spinning speed of the spinning machine is 65 m / min;

[0073] (3) Post-treatment of viscose fibers

[0074] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0075] The first wash temperature is 71℃, and the first wash volume is 62m³. 3 / h, the second water wash temperature is 65℃, and the second water wash volume is 35m³ / h. 3 / h, the three-water washing temperature is 45℃, and the three-water washing volume is 40m³ / h. 3 / h, the final water wash temperature is 72℃, and the final water wash volume is 75m³ / h. 3 / h;

[0076] The desulfurization process involves using a desulfurizing agent at 85.5℃ to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1.7 g / L and the concentration of sodium hydroxide being 3.1 g / L.

[0077] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 52℃ and the pH is 9.5. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.3g / L; the viscose staple fiber undergoes the bleaching process for 3.2min.

[0078] The oiling process involves applying an oil bath solution at 72°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 1.0 g / L, and the concentration of waterborne polyurethane in the oil bath solution is 0.15 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 3.5 using sulfuric acid.

[0079] The drying temperature is 138°C.

[0080] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.11 dtex; length 39 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.7%; ionic conductivity 9.3 mS / cm.

[0081] Example 4

[0082] Prepare ion-conductive viscose fibers according to the following steps:

[0083] (1) Preparation of viscose spinning solution

[0084] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 90% and a methyl cellulose content of 91% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 4.5:100. Then, viscose spinning dope was prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0085] (2) Viscose spinning

[0086] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0087] The coagulation bath contains 105 g / L of sulfuric acid, 9 g / L of zinc sulfate, and 340 g / L of sodium sulfate;

[0088] A polyether-based defoamer is added to the fluffing tank at a rate of 2.2 kg / h, and the inlet steam pressure of the fluffing tank is 1.25 bar.

[0089] The spinning speed of the spinning machine is 60 m / min;

[0090] (3) Post-treatment of viscose fibers

[0091] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0092] The first wash temperature is 71℃, and the first wash volume is 62m³. 3 / h, the second water wash temperature is 65℃, and the second water wash volume is 35m³ / h. 3 / h, the three-water washing temperature is 45℃, and the three-water washing volume is 40m³ / h. 3 / h, the final water wash temperature is 72℃, and the final water wash volume is 75m³ / h. 3 / h;

[0093] The desulfurization process involves using a desulfurizing agent at 85.5℃ to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1.7 g / L and the concentration of sodium hydroxide being 3.1 g / L.

[0094] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 52℃ and the pH is 9.5. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.3g / L; the viscose staple fiber undergoes the bleaching process for 3.2min.

[0095] The oiling process involves applying an oil bath solution at 72°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 1.1 g / L, and the concentration of waterborne polyurethane in the oil bath solution is 0.15 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 3.5 using sulfuric acid.

[0096] The drying temperature is 142°C.

[0097] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.75 dtex; length 40 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.0%; ionic conductivity 12.3 mS / cm.

[0098] Comparative Example 1

[0099] Prepare ion-conductive viscose fibers according to the following steps:

[0100] (1) Preparation of viscose spinning solution

[0101] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 90% and a methyl cellulose content of 91% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 4.5:100. Then, viscose spinning dope was prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0102] (2) Viscose spinning

[0103] The viscose spinning solution prepared above is mixed evenly with titanium dioxide dispersion and then fed into a spinning machine. It is ejected from the spinneret by a metering pump and reacted with a coagulation bath in an acid bath to coagulate and regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles ejected from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0104] The coagulation bath contains 105 g / L of sulfuric acid, 9 g / L of zinc sulfate, and 340 g / L of sodium sulfate;

[0105] The mass ratio of titanium dioxide to water in the titanium dioxide dispersion is 1:5; the mass ratio of titanium dioxide in the titanium dioxide dispersion to cellulose monoxide in the viscose spinning solution is 0.6:100.

[0106] A polyether-based defoamer is added to the fluffing tank at a rate of 2.2 kg / h, and the inlet steam pressure of the fluffing tank is 1.25 bar.

[0107] The spinning speed of the spinning machine is 60 m / min;

[0108] (3) Post-treatment of viscose fibers

[0109] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0110] The first wash temperature is 71℃, and the first wash volume is 62m³. 3 / h, the second water wash temperature is 65℃, and the second water wash volume is 35m³ / h. 3 / h, the three-water washing temperature is 45℃, and the three-water washing volume is 40m³ / h. 3 / h, the final water wash temperature is 72℃, and the final water wash volume is 75m³ / h. 3 / h;

[0111] The desulfurization process involves using a desulfurizing agent at 85.5℃ to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1.7 g / L and the concentration of sodium hydroxide being 3.1 g / L.

[0112] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 52℃ and the pH is 9.5. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.3g / L; the viscose staple fiber undergoes the bleaching process for 3.2min.

[0113] The oiling process involves applying an oil bath solution at 72°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 1.1 g / L, and the concentration of waterborne polyurethane in the oil bath solution is 0.15 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 3.5 using sulfuric acid.

[0114] The drying temperature is 142°C.

[0115] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.75 dtex; length 40 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.0%; ionic conductivity 3.9 mS / cm.

[0116] The main difference between Comparative Example 1 and Example 4 is that titanium dioxide, a matting agent, is added to the viscose spinning step in Comparative Example 1.

[0117] Comparative Example 2

[0118] Prepare ion-conductive viscose fibers according to the following steps:

[0119] (1) Preparation of viscose spinning solution

[0120] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 90% and a methyl cellulose content of 91% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 4.5:100. Then, viscose spinning dope was prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0121] (2) Viscose spinning

[0122] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0123] The coagulation bath contains 105 g / L of sulfuric acid, 9 g / L of zinc sulfate, and 340 g / L of sodium sulfate;

[0124] A polyether-based defoamer is added to the fluffing tank at a rate of 2.2 kg / h, and the inlet steam pressure of the fluffing tank is 1.25 bar.

[0125] The spinning speed of the spinning machine is 60 m / min;

[0126] (3) Post-treatment of viscose fibers

[0127] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0128] The first wash temperature is 71℃, and the first wash volume is 62m³. 3 / h, the second water wash temperature is 65℃, and the second water wash volume is 35m³ / h. 3 / h, the three-water washing temperature is 45℃, and the three-water washing volume is 40m³ / h. 3 / h, the final water wash temperature is 72℃, and the final water wash volume is 75m³ / h. 3 / h; The desulfurization process involves using a desulfurizing agent at 85.5℃ to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide in the desulfurizing agent being 1.7g / L and the concentration of sodium hydroxide being 3.1g / L.

[0129] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 52℃ and the pH is 9.5. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.3g / L; the viscose staple fiber undergoes the bleaching process for 3.2min.

[0130] The oiling process involves applying oil to viscose staple fibers using an oil bath at 72°C. The oil bath is prepared by mixing hydrogen peroxide and an oiling agent, with a hydrogen peroxide concentration of 1.1 g / L. The pH of the oil bath is adjusted to 3.5 using sulfuric acid.

[0131] The drying temperature is 142°C.

[0132] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.75 dtex; length 40 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.0%; ionic conductivity 2.9 mS / cm.

[0133] The main difference between Comparative Example 2 and Example 4 is that waterborne polyurethane was not added to the oil bath of Comparative Example 2.

[0134] Comparative Example 3

[0135] Prepare ion-conductive viscose fibers according to the following steps:

[0136] (1) Preparation of viscose spinning solution

[0137] Softwood dissolving pulp and hardwood dissolving pulp with a whiteness of 90% and a methyl cellulose content of 91% were selected. The softwood dissolving pulp and hardwood dissolving pulp were first mixed at a mass ratio of 4.5:100. Then, viscose spinning dope was prepared through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps.

[0138] (2) Viscose spinning

[0139] The viscose spinning solution prepared above is sent to a spinning machine and sprayed out from the spinneret by a metering pump. It reacts with the coagulation bath in an acid bath and coagulates to regenerate nascent fibers. The coagulated and regenerated nascent fibers are stretched and oriented to form fibers with a certain strength. After being cut, they enter the pile trough. The fibers are dispersed by steam bubbles sprayed from the small holes of the steam jet pipe at the bottom of the pile trough, so that the fiber layer thickness is uniform.

[0140] The coagulation bath contains 105 g / L of sulfuric acid, 9 g / L of zinc sulfate, and 340 g / L of sodium sulfate;

[0141] A polyether-based defoamer is added to the fluffing tank at a rate of 2.2 kg / h, and the inlet steam pressure of the fluffing tank is 1.25 bar.

[0142] The spinning speed of the spinning machine is 60 m / min;

[0143] (3) Post-treatment of viscose fibers

[0144] The viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying process to obtain ion-conductive viscose fiber.

[0145] The first wash temperature is 71℃, and the first wash volume is 62m³. 3 / h, the second water wash temperature is 65℃, and the second water wash volume is 35m³ / h. 3 / h, the three-water washing temperature is 45℃, and the three-water washing volume is 40m³ / h. 3 / h, the final water wash temperature is 72℃, and the final water wash volume is 75m³ / h. 3 / h;

[0146] The desulfurization process involves using a desulfurizing agent at 85.5℃ to desulfurize viscose staple fibers. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1.7 g / L and the concentration of sodium hydroxide being 3.1 g / L.

[0147] The bleaching process uses a bleaching solution; the temperature of the bleaching solution is 52℃ and the pH is 9.5. The bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.3g / L; the viscose staple fiber undergoes the bleaching process for 3.2min.

[0148] The oiling process involves applying an oil bath solution at 72°C to the viscose staple fiber. The oil bath solution is a mixture of hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath solution is 0.5 g / L, and 0.15 g / L of waterborne polyurethane is added to the oil bath solution. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane. The pH value of the oil bath solution is adjusted to 3.5 using sulfuric acid.

[0149] The drying temperature is 142°C.

[0150] The technical parameters of the obtained ion-conductive viscose fiber are as follows: fineness 1.75 dtex; length 40 mm; dry breaking strength ≥2.10 cN / dtex; dry breaking elongation 19.0%~22.0%; defect content ≤1.5 mg / 100g; residual sulfur content ≤4 mg / 100g; whiteness 88.0%; ionic conductivity 2.1 mS / cm.

[0151] The main difference between Comparative Example 3 and Example 4 is that the concentration of hydrogen peroxide in the oil bath of Comparative Example 3 is lower.

[0152] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing ion-conductive viscose fiber, comprising the following steps: The preparation of viscose spinning dope, viscose spinning and post-treatment of viscose fibers are characterized by: The preparation of viscose spinning dope includes the following steps: selecting softwood dissolving pulp and hardwood dissolving pulp with whiteness ≥89% and methyl cellulose content ≥90%; firstly, mixing the softwood dissolving pulp and hardwood dissolving pulp at a mass ratio of 4-5:100; then preparing viscose spinning dope through impregnation, pressing, crushing, aging, xanthation, dissolving and maturation steps; The viscose spinning process includes the following steps: the viscose spinning solution is fed into a spinning machine and ejected from the spinneret by a metering pump. It reacts with a coagulation bath in an acid bath, coagulating to regenerate nascent fibers. The coagulated and regenerated nascent fibers are then stretched and oriented to form fibers with a certain strength. After being cut, the fibers enter a pile tank, where steam bubbles ejected from small holes in the bottom of the pile tank disperse the fibers, resulting in a uniform fiber layer thickness. The coagulation bath contains 100–108 g / L of sulfuric acid, 8–10 g / L of zinc sulfate, and 325–350 g / L of sodium sulfate. The post-processing of the viscose fiber includes the following steps: the viscose staple fiber obtained from the viscose spinning step is fed into a refining machine and successively undergoes a first water washing, desulfurization, a second water washing, bleaching, a third water washing, a final water washing, oiling and drying processes to obtain ion-conductive viscose fiber. The bleaching process uses a bleaching solution; the bleaching solution contains sodium hypochlorite, and the concentration of sodium hypochlorite in the bleaching solution is 2.2-2.5 g / L. The oiling process involves applying an oil bath to the viscose staple fiber. The oil bath is made by mixing hydrogen peroxide, an oiling agent, and waterborne polyurethane. The concentration of hydrogen peroxide in the oil bath is 0.9–1.1 g / L, and the concentration of waterborne polyurethane in the oil bath is 0.1–0.2 g / L. The waterborne polyurethane is a thermally reactive nonionic waterborne polyurethane.

2. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: In the viscose spinning step, a polyether defoamer is added to the fluffing trough at a rate of 2.0–2.5 kg / h; the inlet steam pressure of the fluffing trough is 1.2–1.3 bar; and the spinning speed of the spinning machine is 59–69 m / min.

3. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: In the viscose fiber post-treatment step, the desulfurization process involves using a desulfurizing agent at 85-86°C to desulfurize the viscose staple fiber. The desulfurizing agent contains sodium sulfide and sodium hydroxide, with the concentration of sodium sulfide being 1-2 g / L and the concentration of sodium hydroxide being 3.0-3.3 g / L.

4. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: In the viscose fiber post-treatment step, the temperature of the bleaching solution is 50-55℃ and the pH is 9-10, and the bleaching time of the viscose staple fiber is 3-3.5 minutes.

5. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: In the viscose fiber post-treatment step, the temperature of the oil bath is 70-75°C, and the pH value of the oil bath is adjusted to 3-4 using sulfuric acid.

6. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: The one water washing temperature is 70-75℃, the one water washing amount is 60-70m 3 / h, the two water washing temperature is 60-68℃, the two water washing amount is 30-40m 3 / h, the three water washing temperature is 40-55℃, the three water washing amount is 35-45m 3 / h, the final water washing temperature is 70-75℃, the final water washing amount is 70-80m 3 / h.

7. The method for preparing ion-conductive viscose fiber according to claim 1, characterized in that: In the viscose fiber post-treatment step, the drying temperature is 135-145℃.