Vinasse pulp raw material for lyocell fiber production, lyocell fiber and industrial production method of lyocell fiber

Abstract

The invention discloses a vinasse pulp raw material for lyocell fiber production, lyocell fibers and an industrial production method of the lyocell fibers, and belongs to the technical field of lyocell fiber preparation. Gradient alkali treatment is adopted to replace a traditional pulping cooking process, lignin, hemicellulose, protein, starch and the like in the vinasse can be effectively removed, milder process conditions are achieved, compared with traditional process equipment, the energy consumption is lower, safety is higher, the index of the prepared vinasse pulp raw material can meet the lyocell production requirement, and the method is suitable for industrial production. The performance indexes of the Lyocell fibers obtained through final spinning are excellent, industrial continuous feeding and discharging can be achieved, the production technological process is clear, material loss is smaller, overall energy consumption is lower, and the Lyocell fibers have a certain cost advantage.

Description

Technical Field

[0001] The present invention relates to a distiller's grains pulp raw material for lyocell fiber production, lyocell fiber and an industrial production method thereof, and specifically relates to a distiller's grains pulp raw material suitable for lyocell fiber production prepared from distiller's grains as raw material, lyocell fiber prepared from the distiller's grains pulp raw material, and related industrial production methods for preparing the distiller's grains pulp raw material and lyocell fiber, belonging to the technical field of lyocell fiber preparation. Background Art

[0002] Lyocell fiber, hailed as the "green fiber of the 21st century," is a new type of regenerated cellulose fiber produced by dry-jet wet spinning, using a physical dissolution method. The pulp raw material is dissolved in an aqueous solution of N-methylmorpholine-N-oxide (NMMO) to form a spinning solution. The resulting solution is then dissolved by wet-jet spinning. The entire Lyocell fiber production process is environmentally friendly and pollution-free, with a solvent recovery rate exceeding 99.5%. It boasts superior performance compared to viscose fiber and is widely used in the textile industry. However, Lyocell fiber production requires higher raw material quality than viscose fiber production. Currently, my country's Lyocell fiber production relies primarily on imported raw materials, which has become a bottleneck restricting the development of the country's Lyocell fiber industry. Therefore, finding alternatives to imported raw materials for Lyocell fiber production has become a research hotspot in the Lyocell fiber industry.

[0003] Distillers' grains, a byproduct of the fermentation and distillation of grain crops, primarily come from the brewing and alcohol industries. my country is a major distilled liquor producer, with a massive annual output of baijiu (white liquor), resulting in a significant amount of this byproduct. Currently, most distilleries use traditional methods of landfilling or incineration to dispose of these grains. These disposal methods not only severely harm the soil and environment but also waste resources.

[0004] Wine lees are rich in substances such as cellulose, protein, fat, starch, and mineral elements. The cellulose component can be separated and used in pulp production and cellulose regenerated fiber production. For example, Chinese patent CN115368474A discloses a method for producing green cellulose fiber using wine lees as raw material. This method involves impregnating the wine lees with a dilute alkali solution, filtering, washing, drying, and separating the lees. The resulting wine lees lignin cellulose is then pulverized, alkalized with alkali, and subjected to a delignification process. Finally, the wine lees cellulose is dissolved in an aqueous solution of NMMO and spun to produce regenerated cellulose fiber. However, the delignification process in this method uses the same cooking method used in pulping and papermaking, which requires high temperature and pressure, and the addition of sodium sulfite, a sulfur-containing substance. Manual operation poses safety risks. Furthermore, the cellulose concentration of the spinning solution in this patent is low, only 1.5-3%. This indicates that the wine lees cellulose raw material treated by this patented method is not well soluble in the NMMO aqueous solution, making it impossible to produce a spinning solution with a high cellulose concentration, which is unsatisfactory for current lyocell production needs.

[0005] For example, Chinese patent CN115368474A discloses a method for preparing distiller's grains-based lyocell fiber pulp. This method involves drying, grinding, and screening distiller's grains to obtain distiller's grains powder. Dilute sulfuric acid is used to remove starch. Caustic soda / sodium sulfite is used to remove impurities such as protein, pectin, fatty acids (esters), some lignin, and ash. An aqueous solution of p-toluenesulfonic acid is used to dissolve hemicellulose and lignin. Finally, the pulp is dried and pulverized to obtain distiller's grains-based lyocell fiber pulp, which can be used to produce lyocell fiber. However, this method also uses sodium sulfite, a sulfur-containing substance, and the raw materials are not bleached during the process. The examples also fail to demonstrate the key performance indicators of the final distiller's grains-based pulp, particularly indicators such as degree of polymerization (DP), methyl cellulose (α-cellulose) content, metal ion content, and whiteness. This fails to effectively demonstrate that the distiller's grains-based pulp produced by this method can be used for lyocell fiber production.

[0006] For another example, Chinese patent CN116837654A discloses an environmentally friendly method for preparing distiller's grains-based lyocell fiber pulp. This method involves drying, grinding, and sieving distiller's grains raw materials to obtain distiller's grains powder, which is then subjected to high-temperature and high-pressure cooking, caustic soda / sodium sulfite treatment, amylase treatment, and protease treatment to obtain distiller's grains-based lyocell fiber pulp. However, this method uses the traditional pulping and papermaking cooking process and also adds the sulfur-containing substance sodium sulfite. Manual operation poses risks, and the process is not environmentally friendly. Furthermore, the patent also fails to demonstrate the main performance indicators of the final distiller's grains-based pulp in the examples, failing to effectively demonstrate that the distiller's grains-based pulp obtained by this method can be used for lyocell fiber production.

[0007] Therefore, the current method of preparing lyocell fiber using distiller's grains as raw material still faces industrial bottlenecks. Therefore, the development of efficient industrial production technology for distiller's grains-based lyocell fiber is crucial to achieve large-scale production of this environmentally friendly fiber. Summary of the Invention

[0008] The purpose of the present invention is to provide a distiller's grains pulp raw material for lyocell fiber production, lyocell fiber and an industrial production method thereof. Gradient alkali treatment is adopted to replace the traditional pulping cooking process, which can not only effectively remove lignin, hemicellulose, protein, starch and the like in the distiller's grains, but also has milder process conditions, lower energy consumption and higher safety than traditional process equipment. The distiller's grains pulp raw material prepared by the invention can meet the production requirements of lyocell in terms of indicators. The lyocell fiber finally spun has excellent performance indicators, can realize industrial continuous feeding and discharging, has a clear production process flow, and has less material loss, lower overall energy consumption, and has certain cost advantages.

[0009] The present invention is achieved through the following technical solution: an industrialized production method of distiller's grains pulp raw material for lyocell fiber production, which uses distiller's grains as raw material, sequentially performs gradient alkali treatment, bleaching, acid washing and drying to obtain distiller's grains pulp raw material, Gradient alkali treatment includes the following three alkali treatment steps: The first alkali treatment process: adding the lees to the alkali solution, and then adding the H2O2 solution, controlling the mass ratio of the lees, alkali and H2O2 to be 5-20:10-15:0.1-0.5, and then stirring in a closed manner at 60-90°C for 60-120 minutes, and then washing and dehydrating to obtain the lees raw material after the first alkali treatment; The second alkali treatment process comprises adding the first alkali-treated distiller's grains into an alkali solution, and then adding an H2O2 solution, controlling the mass ratio of the first alkali-treated distiller's grains, alkali, and H2O2 to be 10-20:5-9:0.05-0.1, and then stirring in a closed manner at 60-90°C for 30-90 minutes, and then washing and dehydrating the mixture to obtain the second alkali-treated distiller's grains. The third alkali treatment process: adding the vinasse raw material after the second alkali treatment to the alkali solution, and then adding H2O2 solution, controlling the mass ratio of the vinasse raw material after the second alkali treatment, alkali and H2O2 to be 5-20:0.05-0.5:0.05-0.1, and then stirring in a closed manner at 60-90°C for 30-90 minutes, and then washing and dehydrating with water to obtain the vinasse raw material after the third alkali treatment.

[0010] The alkali solution used in the three alkali treatment steps is NaOH or KOH.

[0011] The bleaching steps include: S1. mixing the third alkali-treated distiller's grains with ClO2 and HCl, controlling the mass ratio of the third alkali-treated distiller's grains to ClO2 and HCl to be 5-20:0.1-0.2:0.01-0.1, bleaching the mixture at 60-80°C for 60-120 min, and then washing and dehydrating the mixture to obtain a bleached distiller's grains; S2. adding the first bleached distiller's grains to an alkaline solution, and then adding a H2O2 solution, controlling the mass ratio of the first bleached distiller's grains to the alkali solution to be 5-20:0.01-0.5:0.01-0.1, and then stirring in a closed container at 70-80°C for 60-120 minutes, and then washing and dehydrating the mixture to obtain the alkaline-extracted distiller's grains; S3. The vinasse raw material after alkali extraction is mixed with ClO2 and NaOH solution, and the mass ratio of the vinasse raw material after alkali extraction, ClO2 and NaOH is controlled to be 5-20:0.01-0.1:0.01-0.1, and then bleached at 60-80 ° C for 60-120 min, and then washed and dehydrated to obtain the second-stage bleached vinasse raw material; S4. Mix the distillers grains after the second-stage bleaching with a NaOH solution and a H2O2 solution, controlling the mass ratio of the distillers grains after the second-stage bleaching to NaOH and H2O2 to be 5-20:0.01-0.1:0.01-0.2, and then bleach the mixture at 70-80°C for 60-120 min, followed by washing and dehydration to obtain the bleached distillers grains.

[0012] In step S2, the alkali in the alkali solution is NaOH or KOH.

[0013] The bleaching treatments in steps S1, S3 and S4 are carried out in an upflow bleaching tower and a downflow bleaching tower.

[0014] Acid washing is to add the bleached vinasse raw material into an acid solution, then add a complexing agent, control the mass ratio of the bleached vinasse raw material, acid and complexing agent to be 5-20:0.01-0.1:0.001-0.05, then stir in a closed manner at 60-80°C for 30-90 minutes, and then wash and dehydrate to obtain the vinasse slurry raw material.

[0015] The acid in the acid solution is formic acid or acetic acid.

[0016] The complexing agent is sodium hexametaphosphate or EDTA.

[0017] A distiller's grains slurry raw material for lyocell fiber production prepared by the above-mentioned industrial production method is characterized in that: the index system of the distiller's grains slurry raw material meets the following requirements: degree of polymerization: DP512-718, methyl fiber content: ≥92.6%, whiteness: ≥84%, ash content: ≤0.07%, iron content: ≤6 ppm, copper content: ≤0.87 ppm, calcium content: ≤76 ppm, and magnesium content: ≤83 ppm.

[0018] The invention discloses an industrialized production method of lyocell fiber. The method comprises the following steps: adding the aforementioned vinasse pulp raw material into an NMMO aqueous solution for swelling and then dissolving the raw material to obtain a spinning solution, and spinning the spinning solution to obtain lyocell fiber.

[0019] The swelling process is to add the vinasse pulp raw material into an NMMO aqueous solution with a concentration of 74-79 wt%, and stir it in a closed state at 78-85°C to fully swell the pulp and obtain a cellulose suspension with a cellulose concentration of 10.5-12 wt%.

[0020] Dissolution is to send the swelled cellulose suspension to a thin film evaporator to dissolve and obtain a spinning solution with a cellulose concentration of 12 to 13.8 wt%. Spinning is a process in which the spinning solution is filtered, wet-spun by dry jet, and then formed in a coagulation bath, and then washed, cut, oiled, and dried to obtain lyocell fiber.

[0021] The lyocell fiber produced by the above industrial production method meets the following index system: linear density: ≤1.34 dtex, dry breaking strength: ≥4.07 cN / dtex, wet breaking strength: ≥3.03 cN / dtex, and whiteness: ≥74%.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention relates to a process for preparing distiller's grains pulp raw material suitable for lyocell fiber production by treating distiller's grains with gradient alkali, bleaching, acid washing and drying. The gradient alkali treatment method can effectively remove lignin, hemicellulose, protein, starch and the like in the distiller's grains, effectively replacing the traditional pulping cooking process. The process conditions are milder, the equipment energy consumption is lower, the manual operation is simpler, the safety is higher, and the obtained distiller's grains pulp has better indicators and can meet the production requirements of lyocell.

[0023] (2) The gradient alkali treatment process of the present invention comprises at least three alkali treatment steps, wherein each alkali treatment process adopts a combination of alkali and H2O2 for treatment. By controlling the different mass ratios of lees, alkali and H2O2 in the three steps, the polymerization degree, methyl cellulose ( ) content, whiteness, etc., to meet the production requirements of lyocell fiber. At the same time, since the treatment temperatures of the three alkali treatment steps are all below 90°C and no high-pressure conditions are required, the process is gentler and safer to operate. Therefore, it can more effectively replace the traditional pulping cooking and oxygen delignification processes.

[0024] (3) The present invention rationally controls the specific performance indicators of the wine slurry raw material, such as degree of polymerization and methyl cellulose ( ) content, lyocell fiber with higher fiber strength can be produced, with dry breaking strength reaching above 4.07 cN / dtex and wet breaking strength reaching above 3.07 cN / dtex.

[0025] (4) The present invention provides the entire process from distiller's grains raw materials to the production of lyocell staple fibers, which can realize industrial continuous feeding and discharging. The production process is clear and the material loss is smaller, the overall energy consumption is lower, and it has certain cost advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the process flow for preparing lyocell fiber using wine lees as raw material in the present invention.

[0027] Figure 2 The invention discloses a device for industrially preparing lyocell fiber using wine lees as raw material.

[0028] Among them, 1 is a high-concentration pulping device, 2 is a pulp pump, 3 is a double-roll pulp washer, 4 is a mixing tube, 5 is a screw pump, 6 is an upflow bleaching tower, 7 is a downflow bleaching tower, 8 is an alkali extraction mixing tank, 9 is an acid washing mixing tank, 10 is a radio frequency dryer, 11 is a thin film evaporator, 12 is a filter, 13 is a spinning machine, 14 is a washing machine, 15 is a cutting machine, 16 is an oiling device, and 17 is a drying device. DETAILED DESCRIPTION

[0029] The objectives, technical solutions and beneficial effects of the present invention are further described in detail below.

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the claimed invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs.

[0031] The present invention is an industrialized production process for preparing lyocell fiber using distiller's grains as raw materials. The production process comprises: subjecting the distiller's grains to a gradient alkali treatment to remove lignin and hemicellulose, followed by bleaching, pickling, and drying to obtain distiller's grains pulp raw material for lyocell fiber production; and swelling and dissolving the distiller's grains pulp raw material to obtain a spinning solution, followed by dry-jet wet spinning to obtain lyocell staple fibers with excellent performance (see Figure 1 In the production process of the present invention, firstly, gradient alkali treatment is adopted to replace the traditional pulping cooking process, which can effectively remove lignin, hemicellulose, protein, starch, etc. in the lees under milder process conditions, thereby achieving specific index control of the lees pulp raw material that meets the production requirements of lyocell; secondly, the lees pulp raw material under the control of specific indicators can obtain lyocell fiber with excellent strength performance, and the entire production process has the process characteristics of lower equipment energy consumption, simpler manual operation, and higher safety. Moreover, the present invention can realize industrial continuous feeding and discharging from the lees raw material to the production of lyocell fiber, has a clear production process flow, less material loss, lower overall energy consumption, and has certain cost advantages.

[0032] The production process of the present invention can be further summarized as follows: (1) Production process of preparing distiller's grains slurry raw materials Using vinasse as raw material, the vinasse slurry raw material is obtained by sequentially performing gradient alkali treatment, bleaching, pickling and drying, as follows: (1) Gradient alkali treatment Three alkali treatment processes are adopted. In the first alkali treatment process, the vinasse raw material is added to a high-concentration pulping device filled with an alkali solution (such as NaOH or KOH), and then a certain amount of H2O2 solution is added. The mass ratio of the vinasse raw material, alkali and H2O2 in the high-concentration pulping device is controlled to be 5-20:10-15:0.1-0.5, and then the vinasse raw material is stirred in a closed manner at 60-90°C for 60-120 minutes, and then washed and dehydrated with water to obtain the vinasse raw material after the first alkali treatment. In the second alkali treatment process, the vinasse raw material after the first alkali treatment is added back to a high-consistency pulping device filled with an alkali solution (such as NaOH or KOH), and a certain amount of H2O2 solution is added to control the mass ratio of the vinasse raw material after the first alkali treatment, alkali and H2O2 in the high-consistency pulping device to be 5-20:5-9:0.05-0.1, and then the vinasse raw material after the first alkali treatment is stirred at 60-90°C for 30-90 minutes, and then washed and dehydrated to obtain the vinasse raw material after the second alkali treatment; in the third alkali treatment process, the vinasse raw material after the second alkali treatment is added back to a high-consistency pulping device filled with an alkali solution (such as NaOH or KOH), and a certain amount of H2O2 solution is added to control the mass ratio of the vinasse raw material after the second alkali treatment, alkali and H2O2 in the high-consistency pulping device to be 5-20:0.05-0.5:0.05-0.1, and then the vinasse raw material after the second alkali treatment is stirred at 60-90°C for 30-90 minutes. min, and then washed and dehydrated to obtain the third alkali-treated distiller's grains raw material.

[0033] (2) Bleaching The above-mentioned vinasse raw material after gradient alkali treatment is bleached, and then washed and dehydrated to obtain the bleached vinasse raw material.

[0034] The bleaching process consists of four steps: ① Chlorine dioxide single-stage bleaching: The vinasse raw material after the third alkali treatment is mixed with chlorine dioxide (ClO2) and hydrochloric acid solution, and the mass ratio of the vinasse raw material, ClO2 and HCl in the mixed material is controlled to be 5-20:0.1-0.2:0.01-0.1. The material is bleached in an upflow bleaching tower and a downflow bleaching tower (bleaching at 60-80°C for 60-120 min), and then washed and dehydrated to obtain the single-stage bleached vinasse raw material.

[0035] ② Alkali extraction: Add the bleached distiller's grains into a stirring device filled with an alkaline solution (such as NaOH or KOH), and then add a certain amount of H2O2 solution. Control the mass ratio of the distiller's grains, alkali and H2O2 in the stirring device to be 10-20:0.01-0.5:0.01-0.1, then stir in a closed manner at 70-80°C for 60-120 min, and then wash and dehydrate to obtain the alkali-extracted distiller's grains.

[0036] ③ Two-stage bleaching with chlorine dioxide: After the vinasse raw material after alkali extraction is mixed with chlorine dioxide (ClO2) and NaOH solution, the mass ratio of the vinasse raw material, ClO2 and NaOH in the mixed material is controlled to be 5-20:0.01-0.1:0.01-0.1, and the material is bleached in an upflow bleaching tower and a downflow bleaching tower (bleaching treatment at 60-80℃ for 60-120 min), and then washed and dehydrated to obtain the two-stage bleached vinasse raw material.

[0037] ④ Hydrogen peroxide bleaching: After the second-stage bleaching of the distiller's grains raw material is mixed with NaOH and H2O2 solution, the mass ratio of the distiller's grains raw material, NaOH and H2O2 in the mixed material is controlled to be 5-20:0.01-0.1:0.01-0.2, and the mixed material is bleached in an upflow bleaching tower and a downflow bleaching tower (bleaching at 70-80°C for 60-120 min), and then washed and dehydrated to obtain the distiller's grains raw material after hydrogen peroxide bleaching.

[0038] (3) Pickling The bleached distiller's grains raw material is added to a stirring device filled with an acid solution (such as formic acid or acetic acid), and then a certain amount of a complexing agent (such as sodium hexametaphosphate or EDTA) is added. The mass ratio of the distiller's grains raw material, the acid and the complexing agent in the stirring device is controlled to be 5-20:0.01-0.1:0.001-0.05, and then the mixture is stirred in a closed manner at 60-80°C for 30-90 minutes, and then washed and dehydrated to obtain a distiller's grains slurry.

[0039] (4) Drying The above-mentioned vinasse slurry is dried at a drying temperature of 60 to 90° C. and a drying time of 120 to 240 min to obtain a vinasse slurry raw material.

[0040] The vinasse slurry raw material prepared by the present invention meets the production requirements of lyocell fiber, and its index system meets the following requirements: degree of polymerization: DP512-718, methylcellulose content: ≥92.6%, whiteness: ≥84%, ash content: ≤0.07%, iron content: ≤6 ppm, copper content: ≤0.87 ppm, calcium content: ≤76 ppm, and magnesium content: ≤83 ppm.

[0041] (2) Production process of Lyocell fiber (1) Swelling of lees slurry raw materials The above-mentioned wine lees pulp raw material is put into a high-concentration pulping device, and then an NMMO aqueous solution with a concentration of 74-79 wt% is added to the device. The device is stirred in a closed manner at 78-85°C to fully swell the pulp and obtain a cellulose suspension with a cellulose concentration of 10.5-12 wt%.

[0042] (2) Preparation of spinning solution The cellulose suspension is transported to a thin film evaporator through a screw pump and dissolved under high temperature and vacuum conditions to obtain a spinning solution.

[0043] During the dissolution process, the feed temperature of the thin-film evaporator was controlled at 78-86°C, and the discharge temperature was 101-110°C. The upper section temperature of the thin-film evaporator was 79-83°C, the middle section temperature was 84-90°C, the lower section temperature was 91-99°C, and the cone bottom temperature was 100-106°C. The cellulose concentration in the spinning solution after dissolution in the thin-film evaporator was 12-13.8 wt%.

[0044] (3) Preparation of Lyocell staple fibers The spinning solution is filtered and then wet-spun by dry jet to be finally formed in a coagulation bath, and then washed, cut, oiled and dried to obtain lyocell staple fibers.

[0045] During dry-jet wet spinning, the spinneret air gap is 5 to 30 mm, the side wind speed is 5 to 25 m / s, and the temperature is 10 to 30° C. Furthermore, in the coagulation bath, an NMMO aqueous solution with a concentration of 5 to 25 wt% is used, the coagulation bath temperature is 10 to 30° C., and the spinning speed is 30 to 45 m / min.

[0046] The index system of the lyocell staple fiber prepared by the present invention meets the following requirements: linear density: ≤1.34 dtex, dry breaking strength: ≥4.07 cN / dtex, wet breaking strength: ≥3.03 cN / dtex, and whiteness: ≥74%.

[0047] In a specific embodiment, to prepare lyocell fiber, Figure 2The industrialized device performs continuous production, has a clear production process flow, low overall energy consumption, simpler process operation, and high safety.

[0048] Specifically, the industrial device includes: a high-concentration pulping device 1, which is used to perform alkali treatment on the lees raw material and swell the lees pulp; a pulp pump 2, which is used to transport pulp porridge with a concentration of 5 to 20 wt%; a double-roll pulp washer 3, which is used to wash and concentrate the pulp porridge and separate the liquid in the fiber; a mixing pipe 4, which is used to mix the washed pulp with the bleaching agent; a screw pump 5, which is used to transport the pulp porridge and ensure high pressure at the pump outlet; an upflow bleaching tower 6, which is a bleaching tower where the pulp flows from bottom to top; a downflow bleaching tower 7, which is a bleaching tower where the pulp flows from top to bottom; an alkali extraction stirring tank 8, which is used to stir the pulp porridge to remove residual hemicellulose and lignin in the raw material; an acid washing stirring tank 9, which is used to stir the pulp porridge to remove ash and metal ions in the raw material; a radio frequency dryer 10, which is used to dry the washed concentrated pulp. a thin film evaporator 11 for evaporating the swollen wine lees slurry, increasing the NMMO concentration, and dissolving the wine lees slurry to obtain a spinning solution; a filter 12 for filtering the spinning solution dissolved by the thin film evaporator; a spinning machine 13 for performing dry-jet wet spinning to prepare lyocell fibers; a washing machine 14 for washing and removing residual NMMO solvent in the fibers; a cutting machine 15 for cutting the washed lyocell fibers into short fibers; an oiling device 16 for oiling the cut short fibers; and a drying device 17 for drying the oiled short fibers.

[0049] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0050] Example 1: Wine lees slurry raw material Using vinasse as raw material, gradient alkali treatment was carried out in sequence: in the first alkali treatment process, the vinasse raw material (10 wt%) was added to a high-concentration pulping device filled with NaOH solution (12 wt%), and then a certain amount of H2O2 solution (0.3 wt%) was added, and the mixture was stirred in a closed manner at 90°C for 90 min, and then washed and dehydrated to obtain the vinasse raw material after the first alkali treatment. During the second alkali treatment process, the vinasse raw material (10 wt%) after the first alkali treatment was added back into a high-concentration pulping device filled with NaOH solution (6 wt%), and then a certain amount of H2O2 solution (0.08 wt%) was added, and the mixture was stirred in a closed manner at 80°C for 6 min, and then washed and dehydrated with water to obtain the vinasse raw material after the second alkali treatment; during the third alkali treatment process, the vinasse raw material (10 wt%) after the second alkali treatment was added back into a high-concentration pulping device filled with NaOH solution (0.2 wt%), and then a certain amount of H2O2 solution (0.08 wt%) was added, and the mixture was stirred in a closed manner at 80°C for 60 min, and then washed and dehydrated with water to obtain the vinasse raw material after the third alkali treatment.

[0051] Bleaching, pickling and drying of the lees raw materials after the third alkali treatment: Bleaching involves four steps. For the first-stage chlorine dioxide bleaching, the distillers' grains (10 wt%) after the third alkaline treatment are mixed with chlorine dioxide (0.15 wt%) and hydrochloric acid solution (0.05 wt%). The mixture is then bleached in upflow and downflow bleaching towers (at 70°C for 120 minutes). The mixture is then washed and dehydrated to obtain the first-stage bleached distillers' grains. For the alkaline extraction, the first-stage bleached distillers' grains (10 wt%) are added to a stirring apparatus containing a 0.2 wt% NaOH solution, followed by a predetermined amount of a 0.05 wt% H2O2 solution. The mixture is then stirred in a closed chamber at 75°C for 60 minutes, and then washed and dehydrated to obtain the alkaline-extracted distillers' grains. For chlorine dioxide bleaching, the alkaline-extracted lees (10 wt%) were mixed with chlorine dioxide (0.05 wt%) and NaOH solution (0.05 wt%), then bleached in upflow and downflow bleaching towers (75°C for 120 min), followed by washing and dehydration to obtain the second-stage bleached lees. For hydrogen peroxide bleaching, the second-stage bleached lees (10 wt%) were mixed with NaOH (0.02 wt%) and H2O2 solution (0.1 wt%), then bleached in upflow and downflow bleaching towers (75°C for 60 min), followed by washing and dehydration to obtain the hydrogen peroxide-bleached lees.

[0052] During acid washing, the bleached distiller's grains (10 wt%) were added to a stirring device containing acetic acid solution (0.05 wt%), and then a certain amount of sodium hexametaphosphate (0.005 wt%) was added. The mixture was then stirred in a closed container at 75°C for 60 min, and then washed and dehydrated to obtain distiller's grains slurry.

[0053] During drying, the vinasse slurry was dried at 80° C. for 180 min to obtain the vinasse slurry raw material.

[0054] Example 2: Wine lees slurry raw material Compared with Example 1, the only difference between this example is the concentration gradient of NaOH used in the gradient alkali treatment. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 1 and are not repeated here. Thus, a distiller's grains slurry raw material is prepared.

[0055] Specifically, in the first alkali treatment process, the concentration of NaOH is 10 wt %; in the second alkali treatment process, the concentration of NaOH is 5 wt %; and in the third alkali treatment process, the concentration of NaOH is 0.05 wt %.

[0056] Example 3: Wine lees slurry raw material Compared with Example 1, the only difference between this example is the concentration gradient of NaOH used in the gradient alkali treatment. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 1 and are not repeated here. Thus, a distiller's grains slurry raw material is prepared.

[0057] Specifically, in the first alkali treatment process, the concentration of NaOH is 15 wt %; in the second alkali treatment process, the concentration of NaOH is 9 wt %; and in the third alkali treatment process, the concentration of NaOH is 0.5 wt %.

[0058] Example 4: Wine lees slurry raw material Compared with Example 1, the only difference between this example is that the concentration gradient of H2O2 used in the gradient alkali treatment process is different. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 1 and are not repeated here. In this way, a wine lees slurry raw material is prepared.

[0059] Specifically, in the first alkali treatment process, the concentration of H2O2 is 0.1 wt%; in the second alkali treatment process, the concentration of H2O2 is 0.05 wt%; in the third alkali treatment process, the concentration of H2O2 is 0.05 wt%.

[0060] Example 5: Wine lees slurry raw material Compared with Example 1, the only difference between this example is that the concentration gradient of H2O2 used in the gradient alkali treatment process is different. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 1 and are not repeated here. In this way, a wine lees slurry raw material is prepared.

[0061] Specifically, in the first alkali treatment process, the concentration of H2O2 is 0.5 wt%; in the second alkali treatment process, the concentration of H2O2 is 0.1 wt%; and in the third alkali treatment process, the concentration of H2O2 is 0.1 wt%.

[0062] Example 6: Lyocell staple fibers The vinasse pulp prepared in Example 1 was put into a high-consistency pulping device, and a 77 wt% NMMO aqueous solution was added to the device. The mixture was stirred in a closed state at 79°C to fully swell the pulp, thereby obtaining a cellulose suspension with a cellulose concentration of 10.8 wt%.

[0063] The cellulose suspension was transported to a thin film evaporator through a screw pump. The upper section temperature of the thin film evaporator was controlled at 82°C, the middle section temperature was 88°C, the lower section temperature was 97°C, the cone bottom temperature was 105°C, the feed temperature of the thin film evaporator was 81°C, and the glue outlet temperature was 102°C. The cellulose was dissolved to obtain a spinning solution with a cellulose concentration of 12.3 wt%.

[0064] The spinning solution is filtered and then wet-spun by dry jet spinning (the air gap of the spinneret is 20 mm, the side blowing speed is 10 m / s, and the temperature is 20°C) in a coagulation bath (aqueous solution of NMMO with a concentration of 20 wt%, a coagulation bath temperature of 20°C, and a spinning speed of 37 m / min) to finally be formed. Lyocell staple fibers are then obtained after washing, cutting, oiling, and drying.

[0065] Example 7: Lyocell staple fibers The vinasse slurry prepared in Example 2 was used to prepare lyocell staple fibers according to the same process as in Example 6, with the only difference being that the process parameters during swelling were slightly adjusted, as follows: During swelling, an NMMO aqueous solution with a concentration of 79 wt% was added, and the mixture was stirred in a closed manner at 85°C to swell and obtain a cellulose suspension with a cellulose concentration of 12 wt%.

[0066] Example 8: Lyocell staple fibers The vinasse slurry prepared in Example 3 was used to prepare lyocell staple fibers according to the same process as in Example 6, with the only difference being that the control temperature of the thin film evaporator was slightly adjusted during dissolution, as follows: The upper section temperature of the thin film evaporator is 83°C, the middle section temperature is 85°C, the lower section temperature is 92°C, the cone bottom temperature is 104°C, the feed temperature of the thin film evaporator is 82°C, the glue outlet temperature is 101°C, and the cellulose concentration is 12.5wt% of the spinning solution.

[0067] Example 9: Lyocell staple fibers The vinasse slurry prepared in Example 4 was used to prepare lyocell staple fibers according to the same process as in Example 6, with the only difference being that the control parameters of the dry-jet wet spinning were slightly adjusted, as follows: The spinneret air gap was 30 mm, the side blowing speed was 18 m / s, and the temperature was 25 °C.

[0068] Example 10: Lyocell staple fibers The vinasse slurry prepared in Example 5 was used to prepare lyocell staple fibers according to the same process as in Example 6, with the only difference being that the control parameters of the coagulation bath were slightly adjusted, as follows: The coagulation bath used an NMMO aqueous solution with a concentration of 25 wt%, the coagulation bath temperature was controlled at 30°C, and the spinning speed was 40 m / min.

[0069] Comparative Example 1: Compared with Example 6, this comparative example differs in that the kraft cooking process and oxygen delignification process in traditional pulping and papermaking are used instead of the gradient alkali treatment process to produce lyocell staple fibers. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 6 and are not repeated here.

[0070] In this comparative example, the kraft cooking process included a 10 wt% lees raw material concentration, a cooking temperature of 165°C, an oxygen pressure of 0.5 MPa, a cooking time of 120 minutes, a NaOH dosage of 17.5% (on a dry basis), and a sulfidation degree of 20% (i.e., the ratio of Na2S added to the total active alkali content). The oxygen delignification process included a 10 wt% lees raw material concentration, a temperature of 160°C, an oxygen pressure of 0.2 MPa, a cooking time of 60 minutes, and a NaOH dosage of 5% (on a dry basis).

[0071] Comparative Example 2: Compared with Example 6, this comparative example differs in that the production of lyocell staple fibers is carried out after the second alkali treatment step in the gradient alkali treatment process is eliminated, and the remaining process steps, equipment used, and related process parameters and conditions are consistent with those in Example 6 and are not described again here.

[0072] Comparative Example 3: Compared with Example 6, this comparative example differs in that a single alkali treatment is used instead of a gradient alkali treatment process to produce lyocell staple fibers. The remaining process steps, equipment used, and related process parameters and conditions are consistent with those in Example 6 and are not described again here.

[0073] In this comparative example, the primary alkali treatment includes: adding the vinasse raw material (10 wt%) to a high-consistency pulping device filled with NaOH solution (15 wt%), then adding a certain amount of H2O2 solution (0.5 wt%), stirring in a closed manner at 90°C for 90 min, and then washing and dehydrating the vinasse raw material to obtain the alkali-treated vinasse raw material.

[0074] Comparative Example 4: Compared with Example 6, this comparative example differs in that the production of lyocell staple fibers is carried out after changing the concentration of the NaOH solution used in the three steps of the gradient alkali treatment process. The remaining process steps, equipment used, and related process parameters and conditions are consistent with Example 6 and are not further described here.

[0075] In this comparative example, in the first alkali treatment step, the concentration of NaOH was 6 wt %; in the second alkali treatment step, the concentration of NaOH was 6 wt %; and in the third alkali treatment step, the concentration of NaOH was 6 wt %.

[0076] Comparative Example 5: Compared with Example 6, this comparative example differs in that the production of lyocell staple fibers is carried out after the second-stage chlorine dioxide bleaching step in the bleaching process is eliminated. The remaining process steps, equipment used, and related process parameters and conditions are consistent with those in Example 6 and are not further described here.

[0077] The above-mentioned vinasse pulp raw materials of Examples 1 to 5, the lyocell staple fibers of Examples 6 to 10, and the vinasse pulp raw materials and lyocell staple fibers of Comparative Examples 1 to 5 were respectively taken and the following index tests were performed. The test results are shown in Tables 1 and 2.

[0078] The index detection method involved in the present invention comprises: Degree of polymerization: FZ / T 50010.3-202 is used to measure the viscosity of the raw materials and then convert it into degree of polymerization. Nail fiber ( ) content: FZ / 50010.4-2011 is used to determine the content of raw materials content.

[0079] Whiteness: FZ / T 50010.7-1998 was used to measure the whiteness of raw materials; GB / T 17644-1998 was used to measure the whiteness of staple fibers.

[0080] Ash content: FZ / T 50010.5-2023 was used to determine the ash content in the raw materials.

[0081] Iron content: FZ / T 50010.6-1998 was used to determine the iron content in the raw materials.

[0082] Copper content: GB / T 8943.1-2008 was used to determine the copper content in the raw materials.

[0083] Calcium and magnesium content: The calcium and magnesium content in the raw materials was determined by digestion method (the method is from "Man-made Fibers" June 2009 edition, Volume 39, Issue 3).

[0084] Linear density: GB / T 14335-2008 was used to measure the linear density of staple fibers.

[0085] Dry breaking strength: GB / T 14337-2008 was used to determine the dry breaking strength of staple fibers.

[0086] Wet breaking strength: GB / T 14337-2008 was used to determine the wet breaking strength of staple fibers.

[0087] Table 1 Performance indicators of the vinasse slurry raw materials in Examples 1-5 and Comparative Examples 1-5 Table 2 Performance indicators of lyocell staple fibers in Examples 6-10 and Comparative Examples 1-5 The following conclusions can be drawn from the results in Tables 1 and 2 above: (1) The vinasse slurries prepared in Examples 1 to 5 can all meet the production requirements of lyocell fibers, and the lyocell fibers finally prepared also have good performance indicators, as shown in Examples 6 to 10.

[0088] (2) By comparing Examples 1 to 3, it can be seen that by varying the amount of alkali used in the gradient alkali treatment process within a certain range, the degree of polymerization (DP) of the lees slurry can be effectively adjusted and controlled. If the amount of alkali used in the gradient alkali treatment process is reduced (Example 2), the degree of polymerization (DP) of the lees slurry will increase; if the amount of alkali used in the gradient alkali treatment process is increased (Example 3), the degree of polymerization (DP) of the lees slurry will decrease.

[0089] (3) By comparing Examples 1, 4, and 5, it can be seen that changing the H2O2 concentration during the gradient alkali treatment within a certain range can also effectively control the degree of polymerization (DP) of the lees slurry. If the H2O2 concentration during the gradient alkali treatment is reduced (Example 4), the degree of polymerization (DP) of the lees slurry will increase; if the H2O2 concentration during the gradient alkali treatment is increased (Example 5), the degree of polymerization (DP) of the lees slurry will decrease.

[0090] (4) By comparing Example 6 with Comparative Example 1, it can be seen that if the gradient alkali treatment process in this patent is replaced by the sulfate cooking process and oxygen delignification process in traditional pulping and papermaking, the lees can also be made into lees pulp that can be used for lyocell fiber production. However, the pulp index is not as good as that of the lees pulp made by the process of this patent, such as degree of polymerization, fiber methyl ( ) content and whiteness will be lower. Furthermore, compared to the distillers' grains pulp produced by this patented process, the final Lyocell fiber will also have lower strength and whiteness. Furthermore, the gradient alkali treatment process in this invention operates at lower temperatures and does not require high pressure, making it a gentler and safer process. It can more effectively replace the traditional pulping and oxygen delignification processes.

[0091] (5) By comparing Example 6, Comparative Example 2 and Comparative Example 3, it can be seen that if one of the alkali treatment processes in the gradient alkali treatment is eliminated (Comparative Example 2), the polymerization degree of the obtained wine lees slurry will increase, and the methyl fiber ( ) content and whiteness decreased, indicating that the gradient alkali treatment process is crucial for the preparation of the lees pulp; if only one alkali treatment process is used (Comparative Example 3), the polymerization degree of the obtained lees pulp will be higher, and the methyl fiber ( ) content and whiteness will also decrease more, and the obtained wine lees slurry has a poor dissolution effect and cannot be spun, which cannot meet the production requirements of lyocell.

[0092] (6) By comparing Example 6 with Comparative Example 4, it can be seen that if the alkali concentration in the gradient alkali treatment is set to the same value (Comparative Example 4), the polymerization degree of the obtained wine lees slurry will increase, and the methyl fiber ( ) content and whiteness decreased, and the obtained lees slurry had poor solubility and could not be spun, indicating that in the gradient alkali treatment process, the first high-concentration alkali treatment was crucial for the preparation of lees slurry.

[0093] (7) By comparing Example 6 with Comparative Example 5, it can be seen that if the two-stage chlorine dioxide bleaching process in the bleaching process is eliminated (Comparative Example 5), the whiteness of the obtained wine lees pulp will be reduced, thereby causing the whiteness of the final lyocell staple fiber to be reduced. This shows that the bleaching process in this patent is crucial to ensuring the whiteness of the wine lees pulp and lyocell fiber subsequently obtained.

[0094] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An industrial production method of distiller's grains slurry as a raw material for lyocell fiber production, characterized in that: Using wine lees as raw material, we carry out gradient alkali treatment, bleaching, pickling and drying in sequence to obtain wine lees pulp raw material. Gradient alkali treatment includes the following three alkali treatment steps: The first alkali treatment process: adding the lees to the alkali solution, and then adding the H2O2 solution, controlling the mass ratio of the lees, alkali and H2O2 to be 5-20:10-15:0.1-0.5, and then stirring in a closed manner at 60-90°C for 60-120 minutes, and then washing and dehydrating to obtain the lees raw material after the first alkali treatment; The second alkali treatment process comprises adding the first alkali-treated distiller's grains into an alkali solution, and then adding an H2O2 solution, controlling the mass ratio of the first alkali-treated distiller's grains, the alkali, and the H2O2 to be 5-20:5-9:0.05-0.1, and then stirring in a closed manner at 60-90°C for 30-90 minutes, and then washing and dehydrating the mixture to obtain the second alkali-treated distiller's grains. The third alkali treatment process: adding the vinasse raw material after the second alkali treatment to the alkali solution, and then adding H2O2 solution, controlling the mass ratio of the vinasse raw material after the second alkali treatment, alkali and H2O2 to be 5-20:0.05-0.5:0.05-0.1, and then stirring in a closed manner at 60-90°C for 30-90 minutes, and then washing and dehydrating with water to obtain the vinasse raw material after the third alkali treatment.

2. The industrial production method of a distiller's grains slurry raw material for Lyocell fiber production according to claim 1, characterized in that: The alkali solution used in the three alkali treatment steps is NaOH or KOH.

3. The industrial production method of distiller's grains slurry raw material for lyocell fiber production according to claim 1, characterized in that: The bleaching steps include: S1. The vinasse raw material after the third alkali treatment is mixed with ClO2 and HCl, and the mass ratio of the vinasse raw material after the third alkali treatment, ClO2 and HCl is controlled to be 5-20:0.1-0.2:0.01-0.1, and then bleached at 60-80°C for 60-120min, and then washed and dehydrated to obtain a bleached vinasse raw material; S2. Adding the first-stage bleached distiller's grains to an alkaline solution, and then adding a H2O2 solution, controlling the mass ratio of the first-stage bleached distiller's grains to the alkaline solution to be 10-20:0.01-0.5:0.01-0.1, and then stirring the mixture in a closed container at 70-80°C for 60-120 minutes, followed by washing and dehydration to obtain an alkaline-extracted distiller's grains. S3. mixing the alkali-extracted distiller's grains with ClO2 and NaOH solutions, controlling the mass ratio of the alkali-extracted distiller's grains to ClO2 and NaOH to be 5-20:0.01-0.1:0.01-0.1, bleaching the alkali-extracted distiller's grains at 60-80°C for 60-120 min, and then washing and dehydrating the bleached distiller's grains to obtain a secondary bleached distiller's grains; S4. Mix the distillers grains after the second-stage bleaching with a NaOH solution and a H2O2 solution, controlling the mass ratio of the distillers grains after the second-stage bleaching to NaOH and H2O2 to be 5-20:0.01-0.1:0.01-0.2, and then bleach the mixture at 70-80°C for 60-120 min, followed by washing and dehydration to obtain the bleached distillers grains.

4. The industrial production method of distiller's grains slurry raw material for lyocell fiber production according to claim 3, characterized in that: In step S2, the alkali in the alkali solution is NaOH or KOH.

5. The industrial production method of distiller's grains slurry raw material for lyocell fiber production according to claim 3, characterized in that: The bleaching treatments in steps S1, S3 and S4 are carried out in an upflow bleaching tower and a downflow bleaching tower.

6. The industrial production method of distiller's grains slurry raw material for lyocell fiber production according to claim 1, characterized in that: Acid washing is to add the bleached vinasse raw material into an acid solution, then add a complexing agent, control the mass ratio of the bleached vinasse raw material, acid and complexing agent to be 5-20:0.01-0.1:0.001-0.05, then stir in a closed manner at 60-80°C for 30-90 minutes, and then wash and dehydrate to obtain the vinasse slurry raw material.

7. The industrial production method of distiller's grains slurry as a raw material for lyocell fiber production according to claim 6, characterized in that: The acid in the acid solution is formic acid or acetic acid.

8. The industrial production method of distiller's grains slurry as a raw material for lyocell fiber production according to claim 6, characterized in that: The complexing agent is sodium hexametaphosphate or EDTA.

9. A vinasse slurry raw material for lyocell fiber production prepared by the industrial production method according to any one of claims 1 to 8, characterized in that: The index system of the wine lees slurry raw material meets the following requirements: degree of polymerization: DP512-718, methyl fiber content: ≥92.6%, whiteness: ≥84%, ash content: ≤0.07%, iron content: ≤6 ppm, copper content: ≤0.87 ppm, calcium content: ≤76 ppm, and magnesium content: ≤83 ppm.

10. An industrial production method of lyocell fiber, characterized in that: The wine slurry raw material according to claim 9 is added to an NMMO aqueous solution for swelling and then dissolved to obtain a spinning solution, and the spinning solution is spun to produce lyocell fibers.

11. The industrial production method of lyocell fiber according to claim 10, characterized in that: The swelling process is to add the vinasse pulp raw material into an NMMO aqueous solution with a concentration of 74-79 wt%, and stir it in a closed state at 78-85°C to fully swell the pulp and obtain a cellulose suspension with a cellulose concentration of 10.5-12 wt%.

12. The industrial production method of lyocell fiber according to claim 10, characterized in that: The dissolution process is to send the swelled cellulose suspension to a thin film evaporator to dissolve the cellulose to obtain a spinning solution with a cellulose concentration of 12 to 13.8 wt%.

13. The industrial production method of lyocell fiber according to claim 10, characterized in that: Spinning is a process in which the spinning solution is filtered, wet-spun by dry jet, and then formed in a coagulation bath, and then washed, cut, oiled, and dried to obtain lyocell fiber.

14. The lyocell fiber produced by the industrial production method according to claim 10, characterized in that: The index system of this lyocell fiber meets the following requirements: linear density: ≤1.34 dtex, dry breaking strength: ≥4.07 cN / dtex, wet breaking strength: ≥3.03 cN / dtex, and whiteness: ≥74%.

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