Low-energy-consumption preparation method of Juncao cellulose fibers

Abstract

The invention discloses a low-energy-consumption preparation method of Juncao cellulose fibers. The low-energy-consumption preparation method comprises the steps of preparation of Juncao pulp and preparation of Juncao fibers. The preparation of the Juncao pulp comprises the steps of pretreatment, blasting treatment, washing and squeezing, cellulose purification, washing, bleaching, secondary washing and concentration of Juncao raw materials to obtain wet pulp; in the step of preparing the Juncao fibers, wet pulp impregnation is adopted, a sodium hydroxide solution is added into the wet pulp, and the solution ratio is adjusted to be 1: (18-22) for impregnation; and then spinning and post-processing are carried out after spinning gel is prepared, so that the Juncao cellulose fiber is obtained. In the fungus grass pulp preparation stage, firstly, fungus grass raw materials are subjected to high-temperature blasting treatment, and the dual purposes of impurity removal and cellulose protection are achieved; the cellulose in the slurry is purified by adopting a two-step method of'enzymolysis and lithium bromide treatment ', and the method has high efficiency and economical efficiency, so that the energy cost of the method is greatly reduced compared with the prior art.

Description

Technical Field

[0001] This invention relates to the field of textile technology, specifically to a technique for preparing cellulose fibers using Juncao grass as a raw material. Background Technology

[0002] Cellulose fiber, as a natural polymer material, occupies an irreplaceable position in many fields such as textiles, clothing, biomedical dressings, and environmentally friendly filter materials due to its excellent moisture absorption, breathability, biocompatibility, and biodegradability. With the popularization of green consumption concepts, market demand continues to grow at a rate of 5%-8% annually. However, the current industrial production of cellulose fiber is highly dependent on wood pulp and cotton pulp, and the supply of these two raw materials is facing severe challenges. From the perspective of timber resources, the growth cycle of high-quality pulping timber is as long as 5-10 years, resulting in a slow production cycle. Furthermore, cotton pulp, made from cotton linters, has a high chemical oxygen demand (COD) concentration in its cooking black liquor, typically reaching 10,000-15,000 mg / L. Wastewater treatment is difficult and costly, with the cost per ton of cotton pulp treatment being 20%-30% higher than that of wood pulp. Under increasingly stringent environmental emission standards, many small cotton pulp production enterprises have ceased production due to their inability to bear the high treatment costs, leading to a continuous decrease in cotton pulp supply and further exacerbating the raw material shortage problem.

[0003] Against this backdrop, finding sustainable, low-cost, and widely available alternative raw materials has become a core issue for the development of the cellulose fiber industry. Juncao, a multifunctional plant that has attracted much attention in recent years, is gradually demonstrating its advantages: on the one hand, Juncao has a high cellulose content and a short growth cycle, with most varieties requiring only 3-8 months from planting to harvest, resulting in high annual yields per acre; on the other hand, Juncao is highly adaptable to its growing environment, capable of being planted in barren mountains, saline-alkali land, and other marginal lands without occupying high-quality arable land, and can also improve the ecological environment through photosynthesis by fixing carbon and releasing oxygen.

[0004] Despite the significant advantages of Juncao (a type of grass) at the raw material level, there are still bottlenecks to be solved in the technology of converting it into cellulose fibers. Most existing technologies employ high-temperature, high-pressure cooking combined with strong oxidants to treat Juncao. While this can purify cellulose, it leads to the breakage of cellulose macromolecular chains, reducing the mechanical properties of the final fiber. For example, Chinese patent CN115584565A discloses a Juncao spinning pulp and its preparation method and application. This method involves cooking Juncao in a solution prepared with alkali, catalyst, and auxiliaries, followed by a pulping process to obtain Juncao spinning pulp. The cooking temperature is as high as 160-175℃, and the cooking time is as long as 4-6 hours. Although the prepared pulp meets the requirements for spinning pulp, the high-temperature cooking not only destroys the natural beneficial components of Juncao itself, preventing the full utilization of resources, but also results in high energy consumption during production. Another method involves extracting cellulose through multiple acid and alkali soakings. This process is not only cumbersome (usually requiring 5-8 steps), but also involves large amounts of acid and alkali, such as sodium hydroxide, which can reach 15%-20% of the raw material mass. The subsequent wastewater treatment costs are high, and the wastewater discharge per ton of product can be more than 1.5 times that of the traditional process, which does not meet the requirements of green production.

[0005] Furthermore, the dissolving pulping process involved in existing cellulose fiber raw materials also has shortcomings. In the dissolving pulping preparation stage, the final step is usually to press the wet pulp into pulp sheets and then dry it. This process has two major problems: First, drying requires a large amount of steam, resulting in high energy costs; second, the individual fibers of Juncao are relatively short, and during the extrusion of the wet pulp into pulp sheets, the fibers are subjected to mechanical compression, causing the fibers to form a tighter physical bond than that of wood pulp or cotton pulp. This tight structure significantly affects the alkali absorption performance in the subsequent impregnation process, reduces impregnation uniformity, and consequently leads to greater fluctuations in the alkali content and methyl cellulose content of the pressed alkali cellulose, affecting the stability of subsequent xanthation and dissolving processes, and ultimately causing fluctuations in the quality of cellulose fibers.

[0006] In summary, these issues collectively restrict the large-scale industrial application of Juncao in the field of cellulose fiber preparation, and also make it difficult to improve the greenness and economic efficiency of existing Juncao cellulose fiber production processes. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a low-energy-consumption method for preparing Juncao cellulose fiber, which addresses the shortcomings of existing technologies. This method aims to solve the problems of resource shortage and environmental pressure caused by the reliance on wood pulp and cotton pulp in the production of existing cellulose fibers, as well as the high energy consumption, loss of beneficial components, and high wastewater treatment costs caused by traditional high-temperature cooking and multiple acid and alkali treatments in the conversion of Juncao into cellulose fibers, and the energy waste and low impregnation efficiency caused by dissolving pulp pressing into boards and drying.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0009] A low-energy-consumption method for preparing Juncao cellulose fiber includes the steps of preparing Juncao pulp and preparing Juncao fiber:

[0010] (1) Preparation of Juncao pulp: Juncao raw materials are pretreated, blasted, washed and pressed, purified by cellulose, washed, bleached, washed twice and concentrated to obtain wet pulp.

[0011] The blasting process includes: cutting the Juncao raw material and putting it into the blasting device, adding 3-5 wt% alkali relative to the dry Juncao material, adding 0.01-0.1 wt% penetrant relative to the dry material, adding 0.5-1.0 wt% cellulose protectant relative to the dry material, adjusting the liquid ratio to 1:4-6, and then releasing the pressure and blasting instantly after holding the pressure for 10-15 minutes at a temperature of 80-100℃ and a pressure of 0.2-0.4 MPa.

[0012] The cellulose purification step includes: adding 0.5-1.0 wt% of a compound biological enzyme preparation relative to the oven-dry slurry to the washed and pressed mushroom straw slurry; adjusting the solid-liquid ratio to 1:10-12 with deionized water; stirring and enzymatically hydrolyzing for 3-4 hours at a temperature of 45-55℃ and a pH of 4.5-5.5; adding a lithium bromide solution with a mass concentration of 30-40% to the system, wherein the amount of lithium bromide added is 12-15% relative to the oven-dry slurry; stirring and reacting for 1.5-2.5 hours at a temperature of 85-95℃; after the reaction is completed, separating the slurry and filtrate to obtain the purified slurry.

[0013] (2) Preparation of Juncao fiber: wet slurry impregnation is carried out by adding sodium hydroxide solution to the wet slurry and adjusting the liquid ratio to 1:18-22 for impregnation; then spinning glue is prepared and spinning and post-treatment are carried out to obtain Juncao cellulose fiber.

[0014] As an improved technical solution, the pretreatment of the raw materials involves selecting dried Juncao grass, removing the roots and impurities, and cutting it into small sections with a length of 2 to 4 centimeters.

[0015] As an improved technical solution, in the blasting treatment, the added penetrant is one of anionic surfactant, nonionic surfactant, or inorganic salt surfactant; the added cellulose protectant is one of sodium sulfite or urea; and the added alkali is one of sodium hydroxide or potassium hydroxide.

[0016] As a preferred technical solution, the penetrant is either sodium dodecylbenzenesulfonate or Tween-80.

[0017] As an improved technical solution, the water washing and pressing involves soaking the exploded mushroom straw slurry in clean water for 1 to 2 hours, and then pressing it through a belt press to control the moisture content of the slurry after pressing to be 50 to 60 wt%.

[0018] As an improved technical solution, in the cellulose purification step, the composite biological enzyme preparation is made by mixing xylanase and cellulase in a mass ratio of 3:1 to 2.

[0019] As an improved technical solution, in the cellulose purification step, the separated filtrate is subjected to vacuum distillation, cooling, centrifugation analysis, and the recovered lithium bromide is reused.

[0020] As an improved technical solution, the water washing involves placing the purified slurry into a water washing tank and repeatedly washing it 3 to 4 times with deionized water at 30 to 40°C, with each washing session lasting 20 to 30 minutes, until the pH value of the washing solution is neutral.

[0021] As an improved technical solution, the bleaching step includes: transferring the washed pulp to a bleaching tank, adding hydrogen peroxide with a mass concentration of 20-25%, the amount of hydrogen peroxide added being 1.0-2.5 wt% relative to the oven-dry pulp, and adding sodium hydroxide to adjust the pH value of the system to 10.0-11.5, bleaching at a temperature of 80-90℃ for 90-180 minutes to remove residual pigments, and bleaching to a cellulose whiteness of 80-85%.

[0022] As an improved technical solution, the secondary washing and concentration steps include: repeatedly washing the bleached pulp with deionized water at 30-40°C 2-3 times, each time for 15-20 minutes, until no hydrogen peroxide residue remains in the washing liquid; then sending the cellulose into a concentration device (such as a centrifugal dewatering machine) to concentrate it to a pulp concentration of 60-70 wt%, thereby obtaining concentrated wet pulp.

[0023] As an improved technical solution, the wet slurry impregnation step includes: adding a sodium hydroxide solution with a mass concentration of 40-45 wt% to the wet slurry, adding a reducing agent of 1.0-1.5 wt% relative to the oven-dry slurry to inhibit the oxidation of cellulose under concentrated alkali and high temperature, adding a chelating agent of 0.1-0.2 wt% relative to the oven-dry slurry to reduce the influence of metal ions on subsequent reactions, and stirring and impregnating for 5-10 minutes at a temperature of 30-48°C.

[0024] As an improved technical solution, the reducing agent is sodium sulfite; the chelating agent is either EDTA or DTPA.

[0025] As an improved technical solution, the preparation of spinning adhesive after wet slurry preparation includes: pressing, aging, xanthation, and dissolving to obtain a dissolving adhesive; the dissolving adhesive is then filtered and degassed to obtain spinning adhesive; the dissolving adhesive contains 8.0-10.0 wt% methyl cellulose, 4.0-6.0 wt% alkali, has a viscosity of 55-70 s, a maturity of 5-10 mL (15% ammonium chloride value), and a net value >100 mL; the spinning adhesive contains 8.0-10.0 wt% methyl cellulose, 4.0-6.0 wt% alkali, has a viscosity of 40-50 s, and a maturity of 8-16 mL (10% ammonium chloride value).

[0026] As an improved technical solution, the pressing involves passing the impregnated slurry through a pressure balance tank to a press to remove excess alkali. The pressure in the press slurry tank is ≤0.04MPa, the hemicellulose concentration in the impregnation reflux liquid is 10-20g / L, and the alkali content in the pressed alkali cellulose is controlled to be 13-17% and the methylcellulose content is 29-35wt%.

[0027] As an improved technical solution, the aging process involves placing alkali cellulose in an aging chamber at a temperature of 25–40°C, with an outlet copper viscosity of 4.5–6.0 mPa·s and an outlet hemicellulose content of <5%.

[0028] As an improved technical solution, the xanthation involves metering the aged cellulose and then feeding it into a xanthation machine for xanthation. The amount of CS2 added to the cellulose is 25-35 wt%, the initial xanthation temperature is 16-20℃, and the final xanthation temperature is 28-32℃.

[0029] As an improved technical solution, the spinning is achieved by spinning the spinning adhesive through a coagulation bath to obtain nascent fibers, and the nascent fibers are then post-treated to obtain the fungus cellulose fibers; the coagulation bath contains 90-110 g / L sulfuric acid, 8-12 g / L zinc sulfate, and 290-340 g / L sodium sulfate, and the temperature is 40-50℃.

[0030] The post-processing involves stretching, cutting, desulfurizing, bleaching, washing, oiling, drying, and packaging the formed filaments to create the finished product.

[0031] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] The present invention discloses a low-energy-consumption method for preparing Juncao cellulose fibers, comprising the steps of preparing Juncao pulp and preparing Juncao fibers. The preparation of the Juncao pulp includes pretreatment, explosion treatment, water washing and pressing, cellulose purification, water washing, bleaching, secondary water washing, and concentration of Juncao raw materials to obtain a wet pulp. The wet pulp is then directly impregnated without board making, followed by gluing and spinning. In the Juncao pulp preparation stage, the present invention first subjectes the Juncao raw materials to high-temperature explosion treatment, employing a composite system of "explosion + alkali + penetrant + protectant" to achieve the dual objectives of impurity removal and cellulose protection. The explosion treatment, through the physical impact force generated by instantaneous pressure release, disrupts the dense structure of the Juncao fibers, creating channels for chemical reagent penetration; the alkali can rapidly degrade the glycosidic bonds in the hemicellulose, while simultaneously loosening the connection between lignin and cellulose; the penetrant can reduce the solid-liquid interfacial tension, promoting sufficient contact between the alkali solution and impurities, and improving reaction efficiency; the protectant can capture free radicals, preventing excessive degradation of cellulose under high-temperature and high-pressure conditions. The cellulose purification stage employs a two-step method of "enzymatic hydrolysis + lithium bromide treatment," which combines high efficiency and economy. Enzymatic hydrolysis is performed under mild conditions, with low energy consumption and no pollution. Cellulose is further purified using a lithium bromide solution under mild conditions. The lithium bromide can be recycled through a recovery process, significantly reducing the cost of chemical reagents.

[0033] This invention eliminates the traditional dissolving pulp "pressing into boards - high-temperature drying" process, directly impregnating with concentrated wet pulp, shortening the production process and reducing steam consumption by 1.0-1.5 tons per ton of product, significantly lowering energy costs. The absence of boards and drying prevents fiber agglomeration at the source, ensuring efficient contact between the impregnation solution and the fibers. The loose structure fully exposes the specific surface area of ​​the fiber surface. Compared to extruded pulp boards (which require moisture absorption and swelling to open the structure), the impregnation solution can directly penetrate into the internal pores of the fiber, improving contact efficiency and shortening impregnation time.

[0034] This invention has the advantage of sustainable resource utilization. It uses Juncao grass as a raw material to produce cellulose fiber. As a perennial herb, Juncao grass has a high cellulose content. Using Juncao grass as a raw material significantly reduces the dependence on wood and cotton linters, and constructs a circular industrial chain of "marginal land planting - Juncao grass raw material production - regenerated cellulose preparation", providing a new green raw material path for the regenerated cellulose industry.

[0035] The regenerated cellulose prepared by this invention has excellent and stable antibacterial properties, with an antibacterial rate of ≥85% against Staphylococcus aureus, ≥80% against Escherichia coli, and ≥80% against Candida albicans. This property is due to the unique components of Juncao itself and the process retention technology. Compared with the traditional high-temperature concentrated alkali treatment, this process adopts a low-temperature, low-alkali mild cellulose purification process. Moreover, not drying the pulp board can avoid the volatilization of beneficial components during the drying process, so that the beneficial components of Juncao can be retained in the fiber. Detailed Implementation

[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] Example 1

[0038] Pretreatment of Juncao raw materials: Select dried Juncao, remove roots and impurities, and cut into small sections with a length of 2 to 4 cm.

[0039] Explosion treatment: After cutting the Juncao raw material, put it into the blasting device, add 3.5% sodium hydroxide relative to the dry material, add 0.03wt% sodium dodecylbenzene sulfonate relative to the dry material, add 0.6wt% sodium sulfite relative to the dry material, adjust the liquid ratio to 1:4, and after holding the pressure for 15 minutes at a temperature of 85℃ and a pressure of 0.25MPa, release the pressure and blast instantly.

[0040] Water washing and pressing: The burst mushroom straw slurry is soaked in clean water for 1 hour and then pressed through a belt press. The moisture content of the slurry after pressing is 52.4 wt%.

[0041] Cellulose purification: A compound bio-enzyme preparation (composed of xylanase and cellulase mixed at a mass ratio of 3:1) was added to the washed and pressed mushroom straw slurry at a relative dryness of 0.6 wt% of the slurry. The solid-liquid ratio was adjusted to 1:10 with deionized water. After enzymatic hydrolysis for 3.5 hours with stirring at 46℃ and pH 4.8, a 30% lithium bromide solution was added to the system. The amount of lithium bromide added was 12.5% ​​of the relative dryness of the slurry. The reaction was carried out with stirring at 88℃ for 1.8 hours. After the reaction was completed, the slurry and filtrate were separated to obtain purified slurry. The slurry showed a cellulose content of 93.8%, a hemicellulose content of 2.9%, and a viscosity of 13.2 mPa·s. The separated filtrate was subjected to vacuum distillation, cooling, centrifugation analysis, and the recovered lithium bromide was recycled.

[0042] Washing: Place the purified slurry into a washing tank and wash it repeatedly with deionized water at 32°C 4 times, each time for 30 minutes, until the pH of the washing solution is neutral.

[0043] Bleaching: Transfer the washed pulp to a bleaching tank, add hydrogen peroxide with a mass concentration of 22% at a volume of 1.5 wt% relative to the oven-dry pulp, and add sodium hydroxide to adjust the pH of the system to 10.5. Bleach for 120 minutes at a temperature of 82℃ to remove residual pigments and bleach to a cellulose whiteness of 82.4%.

[0044] Secondary washing and concentration: The bleached pulp was washed three times with deionized water at 32°C for 20 minutes each time, until no hydrogen peroxide residue remained in the washing liquid. The cellulose was then fed into a centrifugal dewatering machine and concentrated to a pulp consistency of 62.6 wt%, yielding concentrated wet pulp. The wet pulp was tested and found to contain 94.0% methyl cellulose, 1.7% hemicellulose, 11.7 mPa·s viscosity, and 0% lignin.

[0045] Wet slurry impregnation: Add a 42wt% sodium hydroxide solution to the wet slurry to adjust the liquid ratio to 1:19; add 1.1wt% sodium sulfite, a reducing agent relative to the oven-dry slurry, to inhibit the oxidation of cellulose under concentrated alkali and high temperature; add 0.2wt% EDTA, a chelating agent relative to the oven-dry slurry, to reduce the influence of metal ions on subsequent reactions; and impregnate for 10 minutes with stirring at 35°C.

[0046] Pressing: The impregnated pulp is passed through a pressure balance tank to a press to remove excess alkali. The pressure in the press pulp tank is ≤0.04MPa. The hemicellulose concentration in the impregnation reflux liquid is 12.3g / L. The alkali content in the pressed alkali cellulose is 14.4%, and the methylcellulose content is 30.5%.

[0047] Aging: Alkali cellulose is aged in an aging chamber at a temperature of 28°C. The copper viscosity at the aging outlet is 4.8 mPa·s, and the hemicellulose content at the aging outlet is 4.5%.

[0048] Xanthation: The aged cellulose is metered and then fed into a xanthation machine for xanthation. The amount of CS2 added to methyl cellulose is 28 wt%, the initial xanthation temperature is 18℃, and the final xanthation temperature is 28℃.

[0049] Dissolution: Dissolve alkali concentration 5g / L, dissolve water temperature 7℃, dissolve time 50 minutes, dissolve cellulose content in the gel 8.9wt%, alkali content 4.8wt%, viscosity 60.0s, curing degree 7.8mL (15% ammonium chloride value), network value 105mL.

[0050] Spinning: The dissolving adhesive is filtered and degassed to obtain spinning adhesive. The spinning adhesive is spun in a coagulation bath to obtain nascent fibers. The nascent fibers are then post-treated to obtain the fungal cellulose fibers. The spinning adhesive contains 8.9 wt% methyl cellulose, 4.8 wt% alkali, has a viscosity of 48.0 s, and a maturity of 8.5 mL (10% ammonium chloride value). The coagulation bath contains 98.2 g / L sulfuric acid, 10.4 g / L zinc sulfate, and 302 g / L sodium sulfate, and the temperature is 48℃.

[0051] Post-processing: The formed filament bundles are stretched, cut, desulfurized, bleached, washed, oiled, dried and packaged to become finished products.

[0052] Example 2

[0053] Pretreatment of Juncao raw materials: Select dried Juncao, remove roots and impurities, and cut into small sections with a length of 3 to 4 cm.

[0054] Explosion treatment: After cutting the Juncao raw material, put it into the blasting device, add 4.5% sodium hydroxide relative to the dry material, add 0.08wt% penetrant Tween-80 relative to the dry material, add 1.0wt% cellulose protectant urea relative to the dry material, adjust the liquid ratio to 1:6, and after holding the pressure for 10 minutes at a temperature of 95℃ and a pressure of 0.4MPa, instantly release the pressure and blast.

[0055] Water washing and pressing: Soak the burst mushroom straw slurry in clean water for 2 hours, and then press it through a belt press to control the moisture content of the slurry after pressing to 60 wt%.

[0056] Cellulose purification: A compound bio-enzyme preparation (composed of xylanase and cellulase mixed at a mass ratio of 3:2) was added to the washed and pressed mushroom straw slurry at a relative dryness of 0.9 wt% of the slurry. The solid-liquid ratio was adjusted to 1:12 with deionized water. After enzymatic hydrolysis for 3 hours at 52℃ and pH 5.2, a 40% lithium bromide solution was added to the system, with the amount of lithium bromide added being 15% of the relative dryness of the slurry. The reaction was carried out at 92℃ for 1.8 hours. After the reaction was completed, the slurry and filtrate were separated to obtain purified slurry. The slurry was found to contain 95.1% methyl cellulose, 2.4% hemicellulose, and had a viscosity of 14.2 mPa·s. The separated filtrate was subjected to vacuum distillation, cooling, centrifugation analysis, and the recovered lithium bromide was recycled.

[0057] Washing: Place the purified slurry into a washing tank and wash it repeatedly with 40℃ deionized water 3 times, each time for 20 minutes, until the pH of the washing solution is neutral.

[0058] Bleaching: Transfer the washed pulp to a bleaching tank, add hydrogen peroxide with a mass concentration of 25% at a volume of 1.5 wt% relative to the oven-dry pulp, and add sodium hydroxide to adjust the pH of the system to 11.0. Bleach for 100 minutes at a temperature of 90℃ to remove residual pigments and bleach to a cellulose whiteness of 84.0%.

[0059] Secondary washing and concentration: The bleached pulp was washed twice with deionized water at 40°C for 15 minutes each time until no hydrogen peroxide residue remained in the washing solution. The cellulose was then fed into a concentration device and concentrated to a pulp consistency of 70 wt%, yielding concentrated wet pulp. The wet pulp was tested and found to contain 95.2% methyl cellulose, 1.2% hemicellulose, 12.6 mPa·s viscosity, and 0% lignin.

[0060] Wet slurry impregnation: Add a 45wt% sodium hydroxide solution to the wet slurry to adjust the liquid ratio to 1:22; add 1.5wt% sodium sulfite, a reducing agent relative to the oven-dry slurry, to inhibit the oxidation of cellulose under concentrated alkali and high temperature; add 0.2wt% DTPA, a chelating agent relative to the oven-dry slurry, to reduce the influence of metal ions on subsequent reactions; and impregnate for 5 minutes with stirring at 45°C.

[0061] Pressing: The impregnated pulp is passed through a pressure balance tank to a press to remove excess alkali. The pressure in the press trough is 0.03 MPa, the hemicellulose concentration in the impregnation reflux is 16 g / L, and the alkali content in the pressed alkali cellulose is controlled to be 16.4% and the methylcellulose content is 32.8 wt%.

[0062] Aging: Alkali cellulose is aged in an aging chamber at 35°C. The copper viscosity at the aging outlet is 5.5 mPa·s, and the hemicellulose content at the aging outlet is 4.0%.

[0063] Xanthation: The aged cellulose is metered and then fed into a xanthation machine for xanthation. The amount of CS2 added to the cellulose is 32wt%, the initial xanthation temperature is 20℃, and the final xanthation temperature is 32℃.

[0064] Dissolution: Dissolve alkali concentration 12g / L, dissolve water temperature 8℃, dissolve time 550 minutes, dissolve gel content 9.2wt% methyl methacrylate, alkali content 5.5wt%, viscosity 58.5s, curing degree 8mL (15% ammonium chloride value), network value 120mL.

[0065] Spinning: The dissolving adhesive is filtered and degassed to obtain spinning adhesive. The spinning adhesive is spun in a coagulation bath to obtain nascent fibers. The nascent fibers are then post-treated to obtain the fungal cellulose fibers. The spinning adhesive contains 9.2 wt% methyl cellulose, 5.5 wt% alkali, has a viscosity of 50.0 s, and a maturity of 9.5 mL (10% ammonium chloride value). The coagulation bath contains 108.1 g / L sulfuric acid, 10.9 g / L zinc sulfate, and 318 g / L sodium sulfate, and the temperature is 44℃.

[0066] Post-processing: The formed filament bundles are stretched, cut, desulfurized, bleached, washed, oiled, dried and packaged to become finished products.

[0067] Example 3

[0068] Pretreatment of Juncao raw materials: Select dried Juncao, remove roots and impurities, and cut into small sections with a length of 2-3 cm.

[0069] Explosion treatment: After cutting the Juncao raw material, put it into the blasting device, add 4% sodium hydroxide relative to the dry material, add 0.05wt% sodium dodecylbenzene sulfonate relative to the dry material, add 0.7wt% sodium sulfite relative to the dry material, adjust the liquid ratio to 1:5, and after holding the pressure for 13 minutes at a temperature of 90℃ and a pressure of 0.3MPa, release the pressure and blast instantly.

[0070] Water washing and pressing: The burst mushroom straw slurry is soaked in clean water for 1.6 hours and then pressed by a belt press. The moisture content of the slurry after pressing is 55.1 wt%.

[0071] Cellulose purification: A compound bio-enzyme preparation (composed of xylanase and cellulase mixed at a mass ratio of 3:1.5) was added to the washed and pressed mushroom straw slurry at a relative dryness of 0.8 wt% of the slurry. The solid-liquid ratio was adjusted to 1:11 with deionized water. After enzymatic hydrolysis for 3.5 hours with stirring at 50℃ and pH 5.0, a 35% lithium bromide solution was added to the system. The amount of lithium bromide added was 13% of the relative dryness of the slurry. The reaction was carried out with stirring at 90℃ for 2 hours. After the reaction was completed, the slurry and filtrate were separated to obtain purified slurry. The slurry showed a cellulose content of 94.7%, a hemicellulose content of 3.0%, and a viscosity of 11.6 mPa·s. The separated filtrate was subjected to vacuum distillation, cooling, centrifugation analysis, and the recovered lithium bromide was recycled.

[0072] Washing: Place the purified slurry into a washing tank and wash it repeatedly with 35°C deionized water 3 times, each time for 25 minutes, until the pH of the washing solution is neutral.

[0073] Bleaching: Transfer the washed pulp to a bleaching tank, add hydrogen peroxide with a mass concentration of 22% at a volume of 2.0 wt% relative to the oven-dry pulp, and add sodium hydroxide to adjust the pH of the system to 10.6. Bleach for 120 minutes at a temperature of 85℃ to remove residual pigments and bleach to a cellulose whiteness of 83.4%.

[0074] Secondary washing and concentration: The bleached pulp was washed twice with deionized water at 35°C for 18 minutes each time, until no hydrogen peroxide residue remained in the washing liquid; then the cellulose was sent to a concentration device and concentrated to a pulp consistency of 65 wt%, obtaining concentrated wet pulp. The wet pulp was tested and found to contain 95.1% methyl cellulose, 1.4% hemicellulose, a viscosity of 10.1 mPa·s, and 0% lignin.

[0075] Wet slurry impregnation: Add a 42wt% sodium hydroxide solution to the wet slurry to adjust the liquid ratio to 1:20; add 1.2wt% sodium sulfite, a reducing agent relative to the oven-dry slurry, to inhibit the oxidation of cellulose under concentrated alkali and high temperature; add 0.15wt% EDTA, a chelating agent relative to the oven-dry slurry, to reduce the influence of metal ions on subsequent reactions; and impregnate for 8 minutes with stirring at 40°C.

[0076] Pressing: The impregnated pulp is passed through a pressure balance tank to a press to remove excess alkali. The press pulp tank pressure is 0.03 MPa, the hemicellulose concentration of the impregnation reflux liquid is 15 g / L, and the alkali content in the pressed alkali cellulose is 15.5% and the methylcellulose content is 32.6 wt%.

[0077] Aging: Alkali cellulose is aged in an aging chamber at a temperature of 30°C. The copper viscosity at the aging outlet is 5.2 mPa·s, and the hemicellulose content at the aging outlet is 4.2%.

[0078] Xanthation: The aged cellulose is metered and then fed into a xanthation machine for xanthation. The amount of CS2 added to methyl cellulose is 30 wt%, the initial xanthation temperature is 18℃, and the final xanthation temperature is 30℃.

[0079] Dissolution: Dissolve alkali concentration 10g / L, dissolve water temperature 6℃, dissolve time 60 minutes, dissolve cellulose content in the gel 9.0wt%, alkali content 4.5wt%, viscosity 65.4s, curing degree 8.2mL (15% ammonium chloride value), network value 112mL.

[0080] Spinning: The dissolving adhesive is filtered and degassed to obtain spinning adhesive. The spinning adhesive is spun in a coagulation bath to obtain nascent fibers. The nascent fibers are then post-treated to obtain the fungal cellulose fibers. The spinning adhesive contains 9.0 wt% methyl cellulose, 4.5 wt% alkali, has a viscosity of 46.8 s, and a maturity of 8.4 mL (10% ammonium chloride value). The coagulation bath contains 102.3 g / L sulfuric acid, 9.6 g / L zinc sulfate, and 304 g / L sodium sulfate, and the temperature is 45℃.

[0081] Post-processing: The formed filament bundles are stretched, cut, desulfurized, bleached, washed, oiled, dried and packaged to become finished products.

[0082] Comparative Example 1

[0083] The difference between Comparative Example 1 and Example 3 is that the preparation of the mushroom straw pulp did not include the explosion treatment step; otherwise, it was the same as Example 3. The content of methyl cellulose in the dissolved pulp was measured to be 82.5%, hemicellulose to be 8.5%, and lignin to be 3.3%.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 3 is that the preparation of the fungal straw pulp did not include a cellulose purification step; otherwise, it was the same as Example 3. The dissolved pulp was found to contain 78.5% methyl cellulose, 11.6% hemicellulose, and 5.4% lignin.

[0086] Comparative Example 3

[0087] The difference between Comparative Example 3 and Example 3 is that in the cellulose purification step of the preparation of the straw pulp, only the compound biological enzyme preparation was used for enzymatic hydrolysis, and lithium bromide solution was not added for purification after enzymatic hydrolysis. Otherwise, it was the same as Example 3. The content of methyl cellulose in the dissolved pulp was 79.1%, the content of hemicellulose was 6.0%, and the content of lignin was 8.6%.

[0088] Comparative Example 4

[0089] The difference between Comparative Example 4 and Example 3 is that the preparation of the mushroom straw pulp uses the traditional alkaline cooking method to obtain wet pulp, and the preparation method of cellulose fibers is the same as in Example 3.

[0090] Using Juncao (a type of grass) as raw material, with an alkali content of 25wt%, a cooking temperature of 175℃, and a holding time of 180 minutes, the following slurry parameters were tested after cooking:

[0091] The pulp contains 85.2 wt% methyl cellulose, 9.6 wt% hemicellulose, and has a viscosity of 8.8 mPa·s.

[0092] The bleaching process was the same as in Example 3. After secondary washing and concentration, the dissolved pulp was found to have a methyl cellulose content of 85.8%, a hemicellulose content of 7.0%, a viscosity of 8.2 mPa·s, and a lignin content of 0%.

[0093] The press has a high pulp tank pressure, up to 0.14 MPa, and the semi-fiber content at the mature outlet is 9.2%.

[0094] The various performance indicators, antibacterial properties, and production unit consumption of the regenerated cellulose fibers prepared in Examples 1-3 and Comparative Example 4 are shown in Table 1 below.

[0095] Table 1

[0096]

[0097]

[0098] As can be seen from the above embodiments and comparative examples, the present invention uses optimized process steps and parameters to perform high-temperature explosion treatment on Juncao raw materials, achieving the dual goals of impurity removal and cellulose protection; the two-step method of "enzymatic hydrolysis + lithium bromide treatment" is used to purify cellulose in the slurry, which is both efficient and economical; moreover, the concentrated wet slurry is used for direct impregnation, so the method of the present invention not only greatly reduces energy costs compared with the prior art, but also produces Juncao cellulose fibers with good physical and mechanical properties, and well retains the antibacterial properties of Juncao fibers.

[0099] In Comparative Examples 1 to 3, the lack of explosive treatment of the raw materials, the absence of enzymatic hydrolysis using compound bio-enzymes, or the failure to add lithium bromide for purification after enzymatic hydrolysis resulted in significantly higher levels of residual impurities in the fibers and a substantial reduction in cellulose purity. In particular, the large retention of lignin and hemicellulose failed to meet the core purity requirements of the rubber-making and spinning processes, ultimately hindering the normal operation of these processes.

[0100] In contrast, Comparative Example 4 uses the traditional alkaline cooking method for pulping with existing technology to obtain wet pulp. The pulp has a low methyl fiber content and a high hemicellulose content. After impregnation and spinning, the resulting fibers not only have low physical and mechanical properties and high consumption, but also have very poor antibacterial properties.

Claims

1. A low-energy-consumption method for preparing fungal cellulose fibers, characterized in that... The process includes the preparation of mushroom straw pulp and the preparation of mushroom straw fiber. (1) Preparation of Juncao pulp: Juncao raw materials are pretreated, blasted, washed and pressed, purified by cellulose, washed, bleached, washed twice and concentrated to obtain wet pulp. The blasting process includes: cutting the Juncao raw material and putting it into the blasting device; adding 3-5 wt% alkali relative to the dry Juncao material; adding 0.01-0.1 wt% penetrant relative to the dry Juncao material; adding 0.5-1.0 wt% cellulose protectant relative to the dry Juncao material; adjusting the liquid ratio to 1:4-6; and blasting instantaneously after holding the pressure for 10-15 minutes at a temperature of 80-100℃ and a pressure of 0.2-0.4 MPa. The cellulose purification step includes: adding 0.5-1.0 wt% of a compound biological enzyme preparation relative to the oven-dry slurry to the washed and pressed mushroom straw slurry; adjusting the solid-liquid ratio to 1:10-12 with deionized water; stirring and enzymatically hydrolyzing for 3-4 hours at a temperature of 45-55℃ and a pH of 4.5-5.5; adding lithium bromide solution at an amount of 12-15 wt% relative to the oven-dry slurry; stirring and reacting for 1.5-2.5 hours at a temperature of 85-95℃; and separating the slurry and filtrate after the reaction is complete to obtain the purified slurry. (2) Preparation of Juncao fiber: wet slurry impregnation is carried out by adding sodium hydroxide solution to the wet slurry and adjusting the liquid ratio to 1:18-22 for impregnation; after preparing spinning glue, spinning and post-treatment are carried out to obtain Juncao cellulose fiber.

2. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that: In the aforementioned blasting treatment, the added penetrant is one of anionic surfactants, nonionic surfactants, or inorganic salt surfactants; the added cellulose protectant is one of sodium sulfite or urea; and the added alkali is one of sodium hydroxide or potassium hydroxide.

3. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that: In the cellulose purification step, the composite bio-enzyme preparation is made by mixing xylanase and cellulase in a mass ratio of 3:1 to 2.

4. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that: In the cellulose purification step, the separated filtrate is subjected to vacuum distillation, cooling, centrifugation analysis, and the recovered lithium bromide is recycled.

5. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that... The bleaching step includes: transferring the washed pulp to a bleaching tank, adding hydrogen peroxide with a mass concentration of 20-25%, the amount of hydrogen peroxide added being 1.0-2.5 wt% relative to the oven-dry pulp, adjusting the pH of the system to 10.0-11.5, bleaching at a temperature of 80-90℃ for 90-180 minutes to remove residual pigments, and bleaching to a cellulose whiteness of 80-85%.

6. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that... The secondary washing and concentration steps include: washing the bleached pulp with deionized water at 30-40°C 2-3 times, each time for 15-20 minutes, until no hydrogen peroxide residue remains in the washing liquid; then sending the cellulose into a concentration device to concentrate it to a pulp concentration of 60-70 wt%, thus obtaining concentrated wet pulp.

7. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that: The wet slurry impregnation step includes: adding a sodium hydroxide solution with a mass concentration of 40-45 wt% to the wet slurry, adding a reducing agent with a relative dryness of 1.0-1.5 wt% to the dry slurry, adding a chelating agent with a relative dryness of 0.1-0.2 wt% to the dry slurry, and stirring and impregnating for 5-10 minutes at a temperature of 30-48°C.

8. The low-energy preparation method of Juncao cellulose fiber as described in claim 7, characterized in that: The reducing agent is sodium sulfite; the chelating agent is either EDTA or DTPA.

9. The low-energy preparation method of fungal cellulose fiber as described in claim 1, characterized in that: The steps for preparing spinning adhesive after wet slurry preparation include: pressing, aging, xanthation, and dissolving the impregnated slurry to obtain a dissolving adhesive; filtering and degassing the dissolving adhesive to obtain spinning adhesive; the dissolving adhesive has a cellulose content of 8.0–10.0 wt%, an alkali content of 4.0–6.0 wt%, a viscosity of 55–70 s, a maturity of 5–10 mL, and a net value >100 mL; the spinning adhesive has a cellulose content of 8.0–10.0 wt%, an alkali content of 4.0–6.0 wt%, a viscosity of 40–50 s, and a maturity of 8–16 mL.

10. The low-energy preparation method of Juncao cellulose fiber as described in claim 9, characterized in that: The spinning process involves spinning the spinning adhesive through a coagulation bath to obtain nascent fibers, which are then post-treated to obtain the fungus cellulose fibers. The coagulation bath contains 90–110 g / L sulfuric acid, 8–12 g / L zinc sulfate, and 290–340 g / L sodium sulfate, and is held at a temperature of 40–50°C.

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