Preparation method of degradable biomass high-water-absorption short fiber

Abstract

The invention belongs to the technical field of fiber modification, and particularly relates to a preparation method of degradable biomass high-water-absorption short fibers. According to the invention, cellulose short fibers such as plant fibers, regenerated cellulose fibers and the like are used as raw materials, and the degradable biomass short fibers with high water absorption performance are prepared through the technological processes of pre-humidification, cake making, hanging into a reaction tank, alkalization, etherification, neutralization, washing, oiling, wet feeding, wet splitting, drying, metering, packaging and the like. The water absorption rate of the obtained degradable biomass high-water-absorption short fiber is 60 to 100g / g, and the fineness of the degradable biomass high-water-absorption short fiber is 1.29 to 10.0 dtex. The fiber can meet the use requirements in the fields of hygienic personal care products, blood-absorbing cotton medical dressings, surgical pads, dirt treatment bags, water-blocking yarns and water-blocking tapes, agriculture, forestry, landscaping, desert greening, oil exploitation and the like, is an environment-friendly and renewable non-petrochemical functional material, is green and environment-friendly, and has a very wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber modification, and in particular relates to a method for preparing degradable biomass high water-absorbent short fibers. Background Art

[0002] High water-absorbent fibers have been developed since the mid-1980s and have been put on the market in 1996. For example, Japan's Toyobo uses the technical route of acrylic hydrolysis. Domestic high water-absorbent fibers or materials usually use super absorbent resin (SAP) powder and fiber composites. Although they have good water absorption properties, they are not easy to introduce into fabrics, yarns and absorbent products. They are easy to migrate and accumulate, so special processing equipment is often required and they are fixed on the carrier by gluing, fusing or laminating. In addition, when under pressure, its gel is also difficult to form an integrated structure. This type of product mainly serves to be used and discarded, and because it cannot be naturally biodegraded, it is extremely harmful to the environment.

[0003] Cellulose is the most abundant natural renewable resource on earth, which comes from plant photosynthesis and microbial metabolism. Green plants that grow through photosynthesis are the main source of cellulose in nature. It can be divided into cotton, wood, hemp and crop straw, etc. The annual regeneration volume reaches billions of tons, which is the largest "inexhaustible" renewable resource in nature. Cellulose and its derivatives have an increasingly close relationship with humans, and have spread to all aspects of clothing, food, housing and transportation, playing an increasingly important role in human activities and survival.

[0004] Expanding the high value-added utilization of natural resources, mainly cellulose, is a strategic need for the development of national renewable resources and one of the hot areas in the development of global economy, energy and new materials. Cellulose ether is an important cellulose derivative. It is a general term for a variety of derivatives obtained from natural cellulose through alkalization, etherification, purification and drying. It plays an increasingly important role in the national economy. Most cellulose ethers have the following characteristics: (1) The raw material resources are abundant and renewable. The raw material of cellulose ether is natural cellulose, which is the most abundant natural organic renewable resource on earth. Trillions of tons of plant cellulose are regenerated through photosynthesis every year.

[0005] (2) Biodegradable, low-calorie, non-toxic and biocompatible. Most cellulose ethers are environmentally friendly, non-toxic and harmless to humans and animals, and can be used in the food, medicine, cosmetics and other industries.

[0006] (3) The product has a wide range of uses. As an important water-soluble polymer, cellulose ether has applications in oil extraction, ceramics, detergent powder, food, medicine, cosmetics, printing and dyeing, building materials, papermaking, textiles, coatings, leather, polymer polymerization, aerospace and national defense, etc.

[0007] Compared with powder, the advantages of fiber do not come from chemical structure, but are attributed to its physical form or size: 1) Since superabsorbent fiber has a small diameter, usually around 30um, and has a large surface area, it absorbs faster; 2) Since superabsorbent fiber has a large aspect ratio (greater than 100), it can form a tangled structure and is not easy to migrate: 3) Fabrics containing superabsorbent fibers are very soft even when their content is high; 4) Superabsorbent fibers are also easier to use, for example, they can be blended with other fibers and made into non-woven fabrics using traditional equipment; they can also be blended with other fibers into yarn; 5) Superabsorbent fibers can still maintain a fibrous structure after absorbing water, and the gel formed is an entanglement of swollen fibers, so the gel has cohesion and high strength.

[0008] Among cellulose polymers, carboxymethyl cellulose is soluble in water, but it cannot be dehydrated quickly in the presence of high-concentration electrolytes. Currently, there is no technology to dissolve carboxymethyl cellulose into spinning solution and use the solution wet spinning process to make fibers. Carboxymethyl cellulose is similar to cellulose, has no melting point, a color change temperature of 227°C, and a carbonization temperature of 252°C, so the corresponding fiber material cannot be made using the melt spinning process.

[0009] Patent CN116695438A discloses a method for preparing long carboxymethyl cellulose fibers with good hydrophilicity, and provides a method for preparing carboxymethyl cellulose fibers using long lyocell fibers, wherein the long lyocell fiber bundles are wound around a fixed frame, placed in a container, and alkalized, and then adsorbed microspheres are added for etherification. This process is difficult to ensure effective mass transfer between the fibers and the alkalized etherified liquid, which greatly reduces the uniformity of the product quality; at the same time, this method is complex to operate the adsorbed microspheres, uses a lot of chemical raw materials, has a demanding process, and has a high production cost.

[0010] Patent CN114478809A discloses a method for preparing carboxymethyl cellulose fibers. By adding a cationic surfactant, hexadecyltrimethylammonium bromide, during etherification, the surface tension of the fibers is reduced, the hydrophilicity of the fibers is increased, and the reaction efficiency is improved. The invention mentions improvements to the stirred reactor to avoid problems such as fiber hanging, entanglement, and agglomeration during etherification that affect the structure and morphology of the fibers. In the actual process, when short fibers are stirred, problems such as hanging, entanglement, and agglomeration are unavoidable; at the same time, the self-mobile fibers will produce a large amount of sodium carboxymethyl cellulose in the later stage of etherification, which will destroy the original fiber morphology and result in low product yields.

[0011] Patent No. CN201910101739.4 A method for preparing a carboxymethyl cellulose fiber mask is to obtain a carboxymethyl cellulose fiber fabric, rather than a fiber, by alkalizing and etherifying a cellulose fiber non-woven fabric product, thereby limiting the application field.

[0012] There is no method in the prior art for directly preparing carboxymethyl cellulose fibers by alkalizing and etherifying the short fibers of plant fibers (hemp, cotton, fluff, bamboo fibers, etc.) and regenerated cellulose fibers (viscose fibers, lyocell fibers). Summary of the invention

[0013] It is difficult to obtain carboxymethyl cellulose fibers by melt spinning of carboxymethyl cellulose solution in the prior art, and it is also difficult to obtain carboxymethyl cellulose fibers by directly modifying plant fibers, regenerated cellulose fibers, etc. in the form of short-cut fibers.

[0014] In order to solve the problems existing in the prior art, the present invention provides a method for preparing degradable biomass high water-absorbent short fibers to achieve the following invention objectives: 1. Using plant fiber, regenerated cellulose fiber and other cellulose short fibers as raw materials, the problem that short fibers are difficult to directly be treated with alkalization and etherification to form carboxymethyl cellulose fibers is solved. Degradable biomass high water-absorbent short fibers are directly obtained, which have multiple functionalities such as biomass, degradability, high water absorption, hydrophilicity, and low-temperature water solubility, thus expanding their application areas.

[0015] 2. Using plant fiber, regenerated cellulose fiber and other cellulose staple fibers as raw materials, the cellulose staple fibers are made into cakes, and the reaction medium is forced to circulate in a mass transfer and heat transfer manner to avoid excessive expansion of the fibers during etherification, so that the initial cellulose staple fiber morphology is completely retained.

[0016] 3. The modification scope of modified fiber materials has been expanded, such as hemp, cotton, fluff, bamboo fiber, etc. in plant fibers, viscose fiber, lyocell fiber, etc. in regenerated cellulose fibers. The above raw materials can be used to obtain the degradable biomass high water-absorbent short fiber described in the present invention.

[0017] The invention provides a method for preparing degradable biomass short fibers with high water absorption. The short fibers are made of cellulose such as plant fibers and regenerated cellulose fibers as raw materials, and are subjected to the processes of pre-humidification, cake making, hanging into a reaction tank, alkalization, etherification, neutralization, washing, oiling, wet feeding, wet fiber opening, drying, metering and packaging to obtain degradable biomass short fibers with high water absorption. The obtained degradable biomass short fibers with high water absorption have a water absorption rate of 60-100 g / g and a fineness of 1.29-10.0 dtex.

[0018] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing degradable biomass high water-absorbent short fibers comprises the following steps: S1. Using plant fiber, regenerated cellulose fiber and other cellulose short fibers as raw materials, pre-humidifying, beating into cakes, hanging into a reaction tank, and alkalizing in an alkalizing bath until the alkalization degree reaches 60-90%, thereby obtaining alkalized alkali cellulose fibers; S2, removing the alkali bath solution from the alkali cellulose fiber prepared in S1, adding an etherification bath, and continuing the etherification treatment until the degree of etherification (degree of substitution) is 0.6 to 0.95, to obtain an etherified carboxymethyl cellulose fiber primary product, i.e., a biodegradable biomass high water-absorbent short fiber primary product; The carboxymethyl cellulose fiber primary product prepared in S3 and S2 is neutralized in an acid bath, washed with a solvent, oiled, and dried in a high-speed centrifuge to obtain a degradable biomass high-absorbent short fiber semi-finished product; S4. The degradable biomass high water-absorbent short fiber semi-finished product prepared in S3 is subjected to wet feeding, wet fiber opening, drying, metering and packaging to obtain the degradable biomass high water-absorbent short fiber.

[0019] By adopting the above technical scheme, the present invention uses plant fiber, regenerated cellulose fiber and other cellulose short fibers as raw materials, and prepares degradable biomass high water-absorbent short fibers through pre-humidification, cake-making, hanging into a reaction tank, alkalization, etherification, neutralization, washing, oiling, wet feeding, wet fiber opening, drying, metering and packaging and other process processes. The water absorption rate of the degradable biomass high water-absorbent short fibers thus obtained can be controlled according to the needs of the present invention. By pre-humidifying and cake-making of plant fiber, regenerated cellulose fiber and other cellulose short fibers; and forcing cyclic mass transfer and heat transfer during the alkalization and etherification process, it is not only ensured that the short fibers remain unchanged in the later stage, but also accelerates the alkalization and etherification process and uniformity of the cellulose fibers.

[0020] The preparation method has simple steps and controllable conditions, and can stably obtain degradable biomass high water-absorbent short fibers. The prepared degradable biomass high water-absorbent short fibers still maintain complete short fiber morphology and fiber mechanical performance indicators.

[0021] Preferably, the pre-wetting moisture content of the cellulose short fibers in step S1 is 20-40%, and the bulk density of the cake is 150-220 kg / m 3 .

[0022] Preferably, in step S1, the plant fiber is one or more of hemp fiber, cotton fiber, fluff fiber, and bamboo fiber, and the regenerated cellulose fiber is one or more of viscose fiber and lyocell fiber.

[0023] Preferably, the alkalization treatment in step S1 is specifically as follows: dissolving alkali in an alcohol aqueous solution to obtain an alkalization bath with a concentration of 15-25wt%, wherein the alcohol-water ratio in the alcohol aqueous solution is 70-90:10-30, pumping the solution into a reaction tank under high pressure for forced circulation, and reacting at 30-45°C for 2-3h to obtain the alkali cellulose fiber.

[0024] Furthermore, in step S1, the alkali in the alkalization bath is one or more of sodium hydroxide and potassium hydroxide, and the alcohol in the alkalization bath is one or more of methanol, ethanol and isopropanol.

[0025] By adopting the above technical scheme, when preparing alkali cellulose fibers, the fiber moisture content, bulk density, components of the alkalization bath, temperature, and internal circulation volume will directly affect the quality of the primary fibers. To this end, the inventors obtained the above reaction parameters through a large number of experiments, and then strictly controlled the reaction parameters to ensure the appropriate alkalinity, thus laying a good foundation for the preparation of degradable biomass high water-absorbent short fibers.

[0026] Preferably, the etherification treatment process of the alkali cellulose fiber in step S2 is specifically as follows: dissolving the etherifying agent in an alcohol-water solution to obtain an etherification bath with a concentration of 45-65wt%, the alcohol-water ratio in the alcohol-water solution is 70-90:10-30, pumping it into a reaction tank under high pressure for forced circulation, reacting at 50-80°C for 2-3h, and obtaining an etherified carboxymethyl cellulose fiber primary product, i.e., a degradable biomass high water-absorbent short fiber primary product, with an etherification degree (substitution degree) of 0.6-0.95.

[0027] By adopting the above technical solution, during the etherification process, the alkali cellulose fibers are in a loose state or the density of the pressed cake is insufficient. The fibers will swell in large quantities in the later stage of etherification, resulting in changes in fiber morphology and decreased mechanical properties, which will eventually affect not only the quality of the fibers but also the use effect to a certain extent. To this end, the present invention further compacts the alkali cellulose fibers by mechanical means, circulating pump negative pressure, etc. before etherification, and strictly controls the fiber stacking specific gravity to 190-220Kg / m 3 During the etherification process, the carboxyl group in chloroacetic acid can smoothly replace the hydrogen ions on the hydroxyl groups of the glucose units in cellulose, and the etherified fibers can maintain their original fiber morphology, so that the mechanical properties and morphology of the fibers can be maintained.

[0028] The fiber etherification stage is very important. If the water content in the etherification bath is too high, the alkali cellulose fibers will easily swell, making it difficult to ensure the fiber filamentous structure. If the water content is too low, it will be difficult to effectively replace the hydroxyl groups on the fiber glucose. Therefore, under the conditions of an etherification bath concentration of 45-65wt%, an alcohol-water ratio of 70-90:10-30 in an alcohol-water solution, and a temperature of 50-80°C, the degree of substitution of the primary carboxymethyl cellulose fiber obtained is 0.6-0.95, and the subsequent finished product has the best water absorption rate.

[0029] Furthermore, in step S2, the etherifying agent in the etherification bath is one or more of monochloroacetic acid and sodium chloroacetate, and the alcohol in the etherification bath is one or more of methanol, ethanol and isopropanol.

[0030] Preferably, the step S3 specifically comprises neutralizing the primary carboxymethyl cellulose fiber product obtained in S2 to a pH of 6.5 to 8 in an acid bath, washing with a solvent until no chloride ions are detected, oiling, and drying with a high-speed centrifuge to obtain a degradable biomass highly absorbent short fiber semi-finished product.

[0031] Preferably, the acid bath in the S3 step comprises acid, alcohol and water, the concentration of the acid bath is 5-10wt%, the alcohol-water ratio in the acid bath is 60-80:20-40, and the temperature is room temperature; the alcohol-water ratio of the solvent washing is 60-80:20-40, and the temperature is room temperature; the oil bath concentration of the oiling is 0.8-1.0wt%, and the temperature is 40-50°C.

[0032] Preferably, the acid in the acid bath in step S3 is one or more inorganic or organic acids such as sulfuric acid, hydrochloric acid, citric acid, acetic acid and tartaric acid.

[0033] Preferably, the alcohol in the solvent washing in step S3 is one or more of methanol and ethanol.

[0034] Preferably, the S4 step is specifically as follows: the degradable biomass high water-absorbent short fiber semi-finished product is dried and pressed to a moisture content of 50-60wt% and a relatively stable moisture content, and then spread into a silk sheet of a certain width and thickness by a pressing roller. Driven by the pressing roller, it runs to wet feeding and wet fiber opening, and then enters the chain dryer for drying. It is packaged at a fixed weight at the outlet to obtain the degradable biomass high water-absorbent short fiber with a moisture content ≦8%.

[0035] Preferably, the drying temperature of the chain dryer is 70-80°C in zone one, 80-100°C in zone two, 90-110°C in zone three, and 70-80°C in zone four.

[0036] By adopting the above technical scheme, the finished product of biodegradable biomass high water-absorbent short fiber meets the basic requirements of textiles, and the water absorption, water solubility and spinnability of the fiber are further improved. It can be applied to blended high-count yarn, hot air and needle-punched non-woven fabrics. The fiber can meet the use requirements of sanitary personal care products, blood-absorbing cotton medical dressings, surgical pads, sewage treatment bags, water-blocking yarn and water-blocking tapes, agriculture, forestry, landscaping, desert greening, and oil extraction. It is an environmentally friendly, renewable non-petrochemical-based functional material. The product eventually returns to nature and degrades into carbon dioxide (CO2) and water (H2O), so it has a very broad application prospect.

[0037] A degradable biomass short fiber with high water absorption is prepared by the above-mentioned method for preparing a degradable biomass short fiber with high water absorption.

[0038] Due to the adoption of the above technical solution, the technical effects achieved by the present invention are: 1. The present invention provides a method for preparing degradable biomass high water-absorbent short fibers. The obtained short fibers have excellent water absorption and spinnability, meeting the post-processing requirements, wherein the water absorption is 60 to 100 g / g and the fineness is 1.29 to 10.0 dtex.

[0039] 2. When designing the process flow of the preparation of the degradable biomass high-absorbent short fiber of the present invention, the raw materials are widely sourced - plant fibers (hemp, cotton, fluff, bamboo fibers, etc.) and regenerated cellulose fibers (viscose fibers, lyocell fibers). The intermittent and step-by-step fiber modification technology is adopted, and the production is more controllable.

[0040] 3. In the preparation of the degradable biomass high water absorption short fibers, the present invention adopts the method of pre-humidifying and cake-making of short fibers such as plant fibers and regenerated cellulose fibers; forced circulation of mass transfer and heat transfer during the alkalization and etherification process ensures that the short fiber morphology remains unchanged in the later stage of fiber etherification. The preparation method has simple steps and controllable conditions, and can stably obtain degradable biomass high water absorption short fibers. The prepared degradable biomass high water absorption short fibers still maintain complete fiber morphology and fiber mechanical performance indicators.

[0041] 4. The method provided by the present invention obtains degradable biomass high water-absorbent short fibers in the form of modified plant fibers and regenerated cellulose fibers, which solves the problem that carboxymethyl cellulose cannot be made into short fibers by wet method or melt spinning.

[0042] 5. The present invention overcomes the defects of high absorbent materials produced by grafting polymers with acrylic acid, adding super absorbent resin (SAP) to polyester (PET), polypropylene (PP), viscose and other fibers, which are difficult to biodegrade, and avoids the problem of environmental pollution in the later stage; it also overcomes the main disadvantages of the domestic cellulose fiber filament bundle modification route, which is large equipment investment, low single-line production capacity, difficult process operation, limited process control, and uncontrollable final fiber quality. The method successfully prepared degradable biomass high absorbent short fibers with controllable cost, quality and water absorption, which are more widely used and harmless to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a simplified diagram of the process flow for preparing degradable biomass highly absorbent short fibers. DETAILED DESCRIPTION

[0044] The degradable biomass high water absorption short fiber provided by the present invention uses existing plant fiber and regenerated cellulose fiber as raw materials, and mainly takes plant fiber, regenerated cellulose fiber and other cellulose short fibers as examples for explanation. The raw materials are subjected to the process of pre-humidification - cake making - hanging into the reaction tank - alkalization - etherification - neutralization - solvent washing - oiling - centrifugal drying - wet feeding wet fiber opening - chain plate drying - metering packaging, etc., and finally the degradable biomass high water absorption short fiber is obtained.

[0045] The specific water absorption test method of degradable biomass high water absorption short fiber is as follows: The test method for the water absorption rate of high water-absorbent short fibers can refer to the following steps: (1) Sample preparation: Select a certain amount of highly absorbent short fibers (e.g. 0.1 g, accurate to 0.0002 g) and ensure that the sample is completely dry before the experiment.

[0046] (2) Choose a suitable container: Use a container that can accommodate the fiber and its expanded volume after absorbing water. Usually a beaker or other transparent container is used for observation.

[0047] (3) Control water temperature and water quality: The experimental water should be pure water or distilled water to avoid the influence of impurities in the water on the water absorption rate. The water temperature should be controlled within the room temperature (about 20-25℃), because too high or too low water temperature will affect the water absorption performance of the fiber.

[0048] (4) Conduct a water absorption test: Place the highly absorbent staple fibers in a container and add an appropriate amount of water to ensure that the fibers are completely immersed in the water. Record the time when the immersion begins. It is usually necessary to allow the fibers to soak in water for a period of time (e.g., 30 minutes) to reach water absorption equilibrium. During the soaking process, the container can be stirred or shaken appropriately to promote uniform water absorption by the fibers.

[0049] (5) Measure the weight after water absorption: After soaking, carefully remove the fibers after water absorption and filter them with filter paper until no water is left. Use a precision balance to weigh the weight of the fibers after water absorption.

[0050] (6) Calculation of water absorption rate: Based on the measured fiber weight after water absorption and the original dry fiber weight, calculate according to the following formula: Water absorption rate = {fiber weight after water absorption - dry fiber weight} / {dry fiber weight}.

[0051] (7) Repeat the test: To ensure the accuracy of the results, it is recommended to repeat the test several times and take the average value as the final water absorption rate.

[0052] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. The present invention will be further described in detail below in conjunction with the embodiments and comparative examples.

[0053] Example 1: A method for preparing degradable biomass high water-absorbent short fibers, comprising the following steps: S1. Select 1.33dtex×38mm lyocell staple fibers as raw materials, humidify to 25% moisture content according to the volume of the reaction tank, and the fiber cake stacking weight is 180Kg / m 3Accurately measure and hang into the reaction tank. Preparation process of alkali cellulose fiber: dissolve sodium hydroxide in an alcohol aqueous solution to obtain an alkalization bath with a concentration of 18wt%, the mass ratio of ethanol to water in the alcohol aqueous solution is 75:25, and a high-pressure pump is injected into the reaction tank for forced circulation, and react at 30°C for 2.5 hours to obtain alkali cellulose fiber with an alkalinity of 65%.

[0054] S2: Remove the alkali bath solution from the alkali cellulose fiber prepared in S1, and pressurize it again with a cylinder to control the fiber stacking density to 190Kg / m 3 . Etherification treatment process of alkali cellulose fiber; the concentration of the etherification bath obtained by dissolving monochloroacetic acid in ethanol aqueous solution is 45wt%, the mass ratio of ethanol to water is 85:15, and a high-pressure pump is introduced into the reaction tank for forced circulation. The initial reaction temperature is 50°C, the reaction termination temperature is 80°C, and the reaction is cooled after 2 hours to obtain a carboxymethyl cellulose fiber primary product with an etherification degree (substitution degree) of 0.8, which is a biodegradable biomass high water-absorbent short fiber primary product.

[0055] S3. The primary carboxymethyl cellulose fiber product obtained in S2 is neutralized in an acid bath to a pH of 7, washed with solvent to detect no chloride ions, oiled, and dried in a high-speed centrifuge to obtain a degradable biomass highly absorbent short fiber semi-finished product with a moisture content of 55%; wherein the acetic acid concentration in the acid bath is 6.0wt%, the mass ratio of ethanol to water is 65:35, and the temperature is room temperature; the mass ratio of ethanol to water in the solvent washing is 65:35, and the temperature is room temperature; the oil bath concentration of the oiling is 0.9wt%, and the temperature is 45°C.

[0056] S4. The semi-finished product of the degradable biomass high water-absorbent short fiber with a moisture content of 55% prepared in S3 is wet-fed and wet-opened, and the temperature of each zone of the chain dryer is controlled to be 70°C in zone one, 90°C in zone two, 100°C in zone three, and 70°C in zone four; after metering and packaging, the degradable biomass high water-absorbent short fiber with a moisture content of 4.5% is obtained.

[0057] Example 2: A method for preparing degradable biomass high water-absorbent short fibers, comprising the following steps: S1. Select 1.33dtex×38mm lyocell staple fibers as raw materials. According to the volume of the reaction tank, humidify to a moisture content of 40% and a fiber cake bulk density of 160Kg / m 3 Accurately measure and hoist into the reaction tank. Preparation process of alkali cellulose fiber: dissolve sodium hydroxide in an alcohol aqueous solution to obtain an alkalization bath with a concentration of 20wt%, the mass ratio of ethanol to water in the alcohol aqueous solution is 80:20, and a high-pressure pump is injected into the reaction tank for forced circulation, and react at 40°C for 3h to obtain alkali cellulose fiber with an alkalinity of 85%.

[0058] S2: Remove the alkali bath solution from the alkali cellulose fiber prepared in S1, and pressurize it again with a cylinder to control the fiber stacking density to 190Kg / m 3. Etherification treatment process of alkali cellulose fiber; the concentration of the etherification bath obtained by dissolving monochloroacetic acid in an alcohol aqueous solution is 55wt%, the mass ratio of ethanol to water in the alcohol aqueous solution is 90:10, and a high-pressure pump is introduced into a reaction tank for forced circulation. The initial reaction temperature is 50°C, the reaction termination temperature is 80°C, and the reaction is cooled after 2.5 hours of reaction to obtain a carboxymethyl cellulose fiber primary product with an etherification degree (substitution degree) of 0.95, that is, a biodegradable biomass high water-absorbent short fiber primary product.

[0059] S3. The primary carboxymethyl cellulose fiber product obtained in S2 is neutralized in an acid bath to a pH of 7, washed with a solvent to detect no chloride ions, oiled, and dried in a high-speed centrifuge to obtain a degradable biomass highly absorbent short fiber semi-finished product with a moisture content of 58%; wherein the acetic acid concentration in the acid bath is 5.0wt%, the mass ratio of ethanol to water is 70:30, and the temperature is room temperature; the mass ratio of ethanol to water in the solvent washing is 70:30, and the temperature is room temperature; the oil bath concentration of the oiling is 0.9wt%, and the temperature is 45°C.

[0060] S4. The semi-finished product of the degradable biomass high water-absorbent short fiber with a moisture content of 58% prepared in S3 is wet-fed and wet-opened, and the temperature of each zone of the chain dryer is controlled to be 75°C in zone one, 95°C in zone two, 105°C in zone three, and 70°C in zone four; after metering and packaging, the degradable biomass high water-absorbent short fiber with a moisture content of 5.52% is obtained.

[0061] Example 3: A method for preparing degradable biomass high water-absorbent short fibers, comprising the following steps: S1. Select 1.33dtex×38mm lyocell staple fibers as raw materials, humidify to 35% moisture content according to the volume of the reaction tank, and the fiber cake bulk density is 170Kg / m 3 Accurately measure and hang into the reaction tank. Preparation process of alkali cellulose fiber: dissolve sodium hydroxide in an alcohol aqueous solution to obtain an alkalization bath with a concentration of 25wt%, the mass ratio of isopropanol to water in the alcohol aqueous solution is 80:20, and a high-pressure pump is injected into the reaction tank for forced circulation, and react at 30°C for 2.5 hours to obtain alkali cellulose fiber with an alkalinity of 80%.

[0062] S2: Remove the alkali bath solution from the alkali cellulose fiber prepared in S1, and pressurize it again with a cylinder to control the fiber stacking density to 205Kg / m 3 . Etherification treatment process of alkali cellulose fiber; the concentration of the etherification bath obtained by dissolving monochloroacetic acid in an ethanol aqueous solution is 50wt%, the mass ratio of isopropanol to water in the ethanol aqueous solution is 70:30, and a high-pressure pump is introduced into a reaction tank for forced circulation. The initial reaction temperature is 50°C, the reaction termination temperature is 80°C, and the reaction is cooled after 2 hours to obtain a carboxymethyl cellulose fiber primary product with an etherification degree (substitution degree) of 0.7, that is, a biodegradable biomass high water-absorbent short fiber primary product.

[0063] S3. The primary carboxymethyl cellulose fiber product obtained in S2 is neutralized in an acid bath to a pH of 7.5, washed with solvent to detect no chloride ions, oiled, and dried in a high-speed centrifuge to obtain a degradable biomass highly absorbent short fiber semi-finished product with a moisture content of 50%; wherein the concentration of sulfuric acid in the acid bath is 6.0wt%, the mass ratio of ethanol to water is 65:35, and the temperature is room temperature; the mass ratio of ethanol to water in the solvent washing is 65:35, and the temperature is room temperature; the oil bath concentration of the oiling is 1.0wt%, and the temperature is 45°C.

[0064] S4. The semi-finished product of the degradable biomass high water-absorbent short fiber with a moisture content of 50% prepared in S3 is wet-fed and wet-opened, and the temperature of each zone of the chain dryer is controlled to be 70°C in zone one, 90°C in zone two, 100°C in zone three, and 70°C in zone four; after metering and packaging, the degradable biomass high water-absorbent short fiber with a moisture content of 4.59% is obtained.

[0065] Examples 4 to 6 Based on the method of Example 1, the raw materials in step S1 are adjusted. See Table 1 below for specific adjustments.

[0066] Table 1 Raw material adjustment parameter table for Examples 1, 4 to 6 project Example 1 Example 4 Example 5 Example 6 Raw material name Lyocell 1.33dtex*38mm Lyocell 2.5dtex*38mm Cotton pulp board Hemp Fiber Cake stacking density / Kg / m3 180 165 175 170 Alkalinization bath concentration / wt% 18.0 18.0 18.0 18.0 Alkalization time / hr 2.5 2.5 2.5 2.5 Alkalinity / % 65.0 63.3 68.5 60.5 Etherification bath concentration / wt% 45.0 45.0 45.0 45.0 Etherification time / hr 2.0 2.0 2.0 2.0 Degree of etherification 0.80 0.87 0.94 0.65 Water absorption / g / g 78.6 84.5 90.5 63.7 In Examples 7 to 11, based on the method of Example 1, the parameters such as the bath solution and drying temperature in steps S3 and S4 are adjusted. For specific adjustments, see Table 2 below.

[0067] Table 2 Acid bath, solvent washing parameters, and drying temperature of Examples 1, 7 to 11 project Example 1 Example 7 Example 8 Example 9 Example 10 Embodiment 11 Acid bath acid Acetic acid sulfuric acid hydrochloric acid Citric Acid Acetic acid Acetic acid Acid bath concentration / wt% 6.0 6.0 6.0 6.0 5.0 4.0 Acid bath alcohol water ratio 65:35 65:35 65:35 65:35 75:25 80:20 Solvent washing alcohol Ethanol Ethanol Ethanol Ethanol Methanol Methanol Solvent washing alcohol water ratio 65:35 65:35 65:35 65:35 75:25 80:20 Drying zone 1 / ℃ 70 75 70 80 80 85 Drying zone 2 / ℃ 90 90 90 90 90 95 Drying zone 3 / ℃ 100 95 100 100 100 105 Drying zone 4 / ℃ 70 75 70 80 80 80 Water absorption / g / g 78.6 78.3 77.5 78.0 78.1 77.4 Comparative Example 1 Commercially available high water-absorbent fibers were used to directly conduct fiber-related performance testing as Comparative Example 1.

[0068] Table 3 Performance test of degradable biomass high water-absorbent short fibers of Comparative Example 1 and Examples 1 to 11 As shown in Table 3 above, the present invention has overcome the problem of using different cellulose fiber raw materials and chemically modifying them to obtain excellent degradable biomass high water-absorbent short fibers. The water absorption of the degradable biomass high water-absorbent short fibers obtained in Examples 1-11 is within the range of 60 to 100 g / g, the fineness is within the range of 1.29 to 10.0 dtex, and the moisture content of the short fibers is 4.08 to 7.93%. Thus, the fibers have more excellent functionality, spinnability, and practicality.

[0069] Examples 1 to 3 use different alkalization and etherification processes. From the test results, it can be seen that different alkalization and etherification processes and different bath liquid ratios can be used to obtain the corresponding degradable biomass high water-absorbent short fibers using the preparation method of the present invention. Combined with the test results of Examples 4 to 6, it can be seen that different raw materials can also obtain the corresponding products of the present invention.

[0070] The test results of Example 3 show that using different alcohols in the alkalization bath and the etherification bath can also produce degradable biomass short fibers with high water absorption, but when isopropanol is used, the production cost will increase.

[0071] The test results of Examples 1 to 3 show that steps S1 and S2 in the modification process of plant fiber and regenerated cellulose fiber are key processes that affect the water absorption rate of the fiber; steps S3 and S4 involve the removal of impurities from the fiber, the appearance of short fibers, etc., and are indispensable processes.

[0072] The degradable biomass highly absorbent short fibers prepared in Examples 1 to 11 of the present application can be used in fields including but not limited to: medical dressings, functional facial mask materials, maternal and child hygiene products, and adult incontinence products; specifically, they can be made into yarns, non-woven fabrics, flakes, etc. as needed.

[0073] Unless otherwise specified, the ratios and percentages described in the present invention are all weight ratios and weight percentages; and the raw materials are all commercially available.

[0074] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing degradable biomass high water-absorbent short fibers, characterized in that: The preparation method is as follows: plant fiber, regenerated cellulose fiber and other cellulose short fibers are used as raw materials, and the raw materials are subjected to the processes of pre-humidification, cake making, hanging into a reaction tank, alkalization, etherification, neutralization, washing, oiling, wet feeding, wet fiber opening, drying, metering and packaging to obtain degradable biomass short fibers with high water absorption performance, wherein the water absorption rate is 60-100 g / g and the fineness is 1.29-10.0 dtex.

2. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 1, characterized in that: The preparation method comprises the following steps: S1. Using plant fiber, regenerated cellulose fiber and other cellulose short fibers as raw materials, pre-humidifying, beating into cakes, hanging into a reaction tank, and alkalizing in an alkalizing bath until the alkalization degree reaches 60-90%, thereby obtaining alkalized alkali cellulose fibers; S2, removing the alkali bath solution from the alkali cellulose fiber prepared in S1, adding an etherification bath, and continuing the etherification treatment until the degree of etherification (degree of substitution) is 0.6 to 0.95, to obtain an etherified carboxymethyl cellulose fiber primary product, i.e., a biodegradable biomass high water-absorbent short fiber primary product; The carboxymethyl cellulose fiber primary product prepared in S3 and S2 is neutralized in an acid bath, washed with a solvent, oiled, and dried in a high-speed centrifuge to obtain a degradable biomass high-absorbent short fiber semi-finished product; S4. The degradable biomass high water-absorbent short fiber semi-finished product prepared in S3 is subjected to wet feeding, wet fiber opening, drying, metering and packaging to obtain the degradable biomass high water-absorbent short fiber.

3. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 2, characterized in that: The pre-wetting moisture content of the cellulose short fibers in step S1 is 20-40%, and the bulk density of the cakes is 150-220 Kg / m 3 ; In the step S1, the plant fiber is one or more of hemp fiber, cotton fiber, fluff fiber, and bamboo fiber, and the regenerated cellulose fiber is one or more of viscose fiber and lyocell fiber.

4. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 2, characterized in that: The alkalization treatment in step S1 is specifically as follows: dissolving alkali in an alcohol aqueous solution to obtain an alkalization bath with a concentration of 15-25wt%, wherein the alcohol-water ratio in the alcohol aqueous solution is 70-90:10-30, pumping the alkali into a reaction tank for forced circulation, and reacting at 30-45°C for 2-3h to obtain the alkali cellulose fiber; In step S1, the alkali in the alkalization bath is one or more of sodium hydroxide and potassium hydroxide, and the alcohol in the alkalization bath is one or more of methanol, ethanol and isopropanol.

5. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 2, characterized in that: The etherification treatment in step S2 is specifically as follows: dissolving the etherifying agent in an alcohol-water solution to obtain an etherification bath with a concentration of 45-65wt%, wherein the alcohol-water ratio in the alcohol-water solution is 70-90:10-30, pumping the solution into a reaction tank under high pressure for forced circulation, reacting at 50-80°C for 2-3h, and obtaining an etherified carboxymethyl cellulose fiber primary product, i.e., a degradable biomass high water-absorbent short fiber primary product.

6. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 5, characterized in that: In the step S2, the etherifying agent in the etherification bath is one or more of monochloroacetic acid and sodium chloroacetate, and the alcohol in the etherification bath is one or more of methanol, ethanol and isopropanol.

7. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 2, characterized in that: Specifically, the step S3 comprises neutralizing the primary carboxymethyl cellulose fiber product obtained in S2 to a pH of 6.5 to 8 by acid bath, washing with solvent until no chloride ions are detected, oiling, and drying by high-speed centrifuge to obtain a semi-finished product of degradable biomass high water-absorbent short fiber.

8. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 7, characterized in that: The acid bath in step S3 includes acid, alcohol and water, the concentration of the acid bath is 5-10wt%, the alcohol-water ratio in the acid bath is 60-80:20-40, and the temperature is room temperature; the alcohol-water ratio of the solvent washing is 60-80:20-40, and the temperature is room temperature; the oil bath concentration of the oiling is 0.8-1.0wt%, and the temperature is 40-50°C; The acid in the acid bath in step S3 is one or more of sulfuric acid, hydrochloric acid, citric acid, acetic acid and tartaric acid; The alcohol in the solvent washing in step S3 is one or more of methanol and ethanol.

9. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 2, characterized in that: Specifically, the S4 step comprises the following steps: the semi-finished degradable biomass high water-absorbent short fiber is spun dry and pressed to a moisture content of 50-60wt%, and then spread into a silk sheet of a certain width and thickness by a pressing roller. Driven by the pressing roller, the silk sheet is wet fed and wet opened, and then enters a chain dryer for drying. The semi-finished degradable biomass high water-absorbent short fiber is packaged at a fixed weight at the outlet to obtain the degradable biomass high water-absorbent short fiber with a moisture content ≤8%.

10. The method for preparing a degradable biomass high water-absorbent short fiber according to claim 9, characterized in that: The drying temperature of the chain plate dryer is 70-80°C in zone one, 80-100°C in zone two, 90-110°C in zone three, and 70-80°C in zone four.

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