Bamboo fiber with controllable shape as well as preparation method and application of bamboo fiber
By combining processing and steam explosion technology, the problems of low efficiency and difficulty in controlling the morphology of bamboo fiber preparation have been solved, and high-strength, highly dispersible, environmentally friendly and energy-saving bamboo fibers with controllable morphology have been prepared, thus expanding their application range.
Patent Information
- Application Number
- CN202511502942.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-20
- Publication Date
- 2025-11-18
AI Technical Summary
Existing methods for preparing bamboo fiber suffer from problems such as low preparation efficiency, difficulty in controlling fiber morphology, uneven fiber quality, and environmental pollution.
A combined treatment process using steam explosion technology, including physical compaction and fiber opening, chemical/biological treatment, and steam explosion, was employed. By controlling the temperature, pressure, and depressurization rate of the steam explosion, and combining it with enzyme and bacterial treatment, bamboo fibers with controllable morphology were prepared.
It has achieved efficient preparation of bamboo fiber with controllable length, excellent fiber quality, environmental protection and energy saving, broadened application fields, improved fiber strength and dispersibility, and reduced production costs.
Smart Images
Figure CN120967712A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of fibers, in particular to a morphologically controllable bamboo fiber and a preparation method and application thereof. BACKGROUND
[0002] Bamboo grows rapidly and has high renewability. Compared with other wood resources, bamboo can reach the mature harvesting standard in a relatively short time, which makes bamboo resources can be quickly recycled to effectively meet the continuous demand of the market for bamboo fiber. Bamboo fiber has a growing proportion in various environmentally friendly materials due to its high strength, biodegradability and other advantages.
[0003] At present, the methods for preparing bamboo fiber are usually chemical method, physical method and biological method. Among them, the chemical method can remove components such as gum, lignin and hemicellulose in bamboo. However, the existing chemical method has the disadvantages of polluting the environment and damaging the bamboo fiber. The physical method can separate the bamboo fiber from the base tissue and other cells. However, the existing physical method has poor uniformity of the prepared bamboo fiber. The biological method for preparing bamboo fiber has the advantages of environmental friendliness and simple process. However, the existing biological method for preparing bamboo fiber has the disadvantages of long cycle and low preparation efficiency. By using a method combining two or more processes, the advantages of multiple processes are utilized to make up for the shortcomings, so that the performance and efficiency of the prepared bamboo fiber are better than those of a single process. However, the existing method combining two or more processes has the problems of difficulty in controlling the morphology (length) of the prepared bamboo fiber, contradiction between fiber quality (toughness, adaptability to process) and processing efficiency, and damage to the bamboo fiber. SUMMARY
[0004] Therefore, the present application aims to provide a morphologically controllable bamboo fiber and a preparation method and application thereof. The preparation method provided by the present application can realize controllable morphology (length) of the prepared bamboo fiber, high preparation efficiency, small damage to the bamboo fiber, and good fiber quality.
[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: The present application provides a preparation method of a morphologically controllable bamboo fiber, comprising the following steps: The bamboo is subjected to combined treatment to obtain a combined treatment bamboo; the combined treatment comprises physical rolling and fibrillation treatment and chemical / biological treatment, the chemical / biological treatment comprises at least one of alkali soaking, enzyme treatment and fungus treatment; the physical rolling and fibrillation treatment and the chemical / biological treatment have no time sequence; The joint processing bamboo is subjected to steam explosion treatment to obtain controllable bamboo fibers; the steam explosion treatment conditions include: explosion temperature of 110-200 DEG C, explosion pressure of 1-3 MPa, explosion time of 2-8 min, and pressure relief speed of 0.1-10 MPa / s.
[0006] Preferably, the physical rolling and opening treatment has a rolling gap of 1-4 mm and a rolling frequency of 1-20 times. The physical rolling and opening treatment further includes rubbing and sorting.
[0007] Preferably, the bamboo is further subjected to pretreatment before use, and the pretreatment preferably includes one or more of microwave pretreatment, ultrasonic pretreatment and biological pretreatment.
[0008] Preferably, the chemical composition of the alkali solution includes an alkaline reagent, an additive and water; the additive includes one or more of a chelating agent, an alkali-resistant penetrant, a buffer, a dispersing agent and an antifoaming agent; and the pH value of the alkali solution is 8-12. The temperature of the alkali solution soaking is 25-100 DEG C, and the time is 0.5-72 h.
[0009] Preferably, the enzyme solution used in the enzyme treatment includes a biological enzyme and water, and the biological enzyme includes one or more of hemicellulase, cellulase, xylanase, pectinase and ligninase; and the pH value of the enzyme solution is 5.5-8. The ratio of the activity of the enzyme solution to the dry weight of the bamboo is 5-40 IU / g. The temperature of the enzyme treatment is 30-60 DEG C, and the time is 2-72 h. The enzyme treatment includes at least one of pressurized spraying and vacuum impregnation; the pressurized spraying includes sequentially performing low-pressure spraying and medium-pressure spraying, the pressure of the low-pressure spraying is 0.1-0.4 MPa, and the time is 0.5-8 h; the pressure of the medium-pressure spraying is 0.5-2 MPa, and the time is 0.3-6 h.
[0010] Preferably, the bacteria used in the bacteria treatment include one or more of white rot fungi, brown rot fungi and soft rot fungi. The temperature of the bacteria treatment is 30-55 DEG C, and the time is 0.3-72 h.
[0011] Preferably, in the steam explosion treatment, the ratio of the dry weight of the bamboo to the volume of water is 1-4 kg:1 L. The steam explosion treatment includes at least one of continuous steam explosion treatment and intermittent steam explosion treatment.
[0012] Preferably, the steam explosion treatment further comprises: performing solid-liquid separation, and performing fiber sorting on the obtained solid fibers or sequentially performing biological homogenization treatment and fiber sorting.
[0013] The application also provides the morphologically controllable bamboo fibers prepared by the preparation method. The length of the short bamboo fibers is less than 25mm. The length of the medium bamboo fibers is 25-40mm. The length of the long bamboo fibers is greater than 40mm.
[0014] The application also provides the application of the morphologically controllable bamboo fibers as fillers of organic materials or inorganic materials.
[0015] The application realizes efficient separation of fibers by adopting physical rolling and opening fiber treatment, steam permeation and diffusion efficiency in the subsequent steam explosion treatment process, and the instant energy release effect of the steam explosion treatment, effectively shortens the preparation period of the bamboo fibers, has high preparation efficiency of the bamboo fibers, and provides conditions for fast steam explosion treatment under low temperature and low pressure, significantly reduces energy consumption, constructs an efficient and energy-saving green manufacturing system of the bamboo fibers, and significantly reduces damage of the bamboo fibers.
[0016] The application adopts mild and environmentally-friendly pretreatment reagents, reduces use of chemical medicines, significantly reduces environmental pollution risk, reduces waste liquid treatment cost, and improves safety of the production process and resource sustainable utilization rate.
[0017] The application adopts physical rolling and opening fiber treatment, chemical / biological treatment and steam explosion treatment process, and realizes high efficiency and high yield in the bamboo fiber preparation process.
[0018] As shown in the embodiment test results, the length and fiber length of the bamboo fiber prepared by the application are controllable, the prepared bamboo fiber with controllable morphology has a low agglomeration index, the tensile strength can reach 580 MPa, the yield of the bamboo fiber with high tensile strength can reach 85%, and the yield is high.
[0019] The bamboo fiber with controllable morphology prepared by the application is used in the textile field to make high-count yarns by virtue of good spinnability, and is used as a reinforcing material in the field of composite materials, high-end fields of aviation and automobile manufacturing; the short bamboo fiber is used in the papermaking field to mix with wood pulp to improve the performance of various paper, and is used in the material field to make brake pads, and is used in the field of filling materials to improve the processing performance of rubber products, injection molding, and to enhance the hardness and wear resistance of the reinforcing material.
[0020] Further, the application uses ultrasonic pretreatment, biological pretreatment and microwave pretreatment, which can further reduce the explosion temperature of the bamboo fiber in the subsequent steam explosion process, save energy and reduce consumption, and also reduce the damage to the bamboo fiber.
[0021] Further, the application adopts a continuous steam explosion treatment process, the preparation efficiency of the bamboo fiber is high, and high-yield output of the bamboo fiber can be realized; moreover, the process is also provided with a waste heat recovery system, which can further reduce energy consumption and effectively promote the utilization of resources. In the continuous treatment process of the material, the consistency of the product quality is good, the production efficiency is greatly improved, large-scale production is suitable, and finally the bamboo fiber product with controllable morphology can be obtained.
[0022] The method for preparing the bamboo fiber by combining the process currently adopted has the problems of difficult recovery and utilization of chemical reagents, waste of resources and environmental pollution in environmental protection.
[0023] The alkali immersion can improve the interfacial compatibility of the bamboo fiber and the polymer matrix such as resin, and the interfacial compatibility between the polymer and the bamboo fiber in the bamboo fiber polymer composite provided by the application is strong, and the mechanical properties of the bamboo fiber polymer composite are excellent. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 The preparation process flow chart of the bamboo fiber with controllable morphology in Example 1 is shown in the figure. DETAILED DESCRIPTION
[0025] The application provides a preparation method of bamboo fiber with controllable morphology, which comprises the following steps: The bamboo material is subjected to combined treatment to obtain a combined treatment fiber; the combined treatment comprises physical rolling and fibrillation treatment and chemical / biological treatment, the chemical / biological treatment comprises at least one of alkali immersion, enzyme treatment and bacteria treatment; and the physical rolling and fibrillation treatment and the chemical / biological treatment have no time sequence; The combined treatment fiber is subjected to steam explosion treatment to obtain bamboo fiber with controllable morphology.
[0026] The materials and devices used in the present application are commercially available unless specifically stated otherwise.
[0027] The bamboo is subjected to combined treatment to obtain the combined treatment fiber; the combined treatment comprises physical rolling and fibrillation treatment and chemical / biological treatment, the chemical / biological treatment comprises at least one of lye soaking, enzyme treatment and bacteria treatment; the physical rolling and fibrillation treatment and the chemical / biological treatment have no time sequence.
[0028] In the present application, the bamboo preferably comprises one or more of Phyllostachys edulis, Dendrocalamus latiflorus and Dendrocalamus giganteus, and the bamboo does not need to be differentiated into green, flesh and yellow, and the node does not need to be removed. The bamboo used in the present application does not need to be subjected to node removal treatment, simplifies the production process, is suitable for large-scale preparation of bamboo fiber, and improves the production efficiency of the bamboo fiber.
[0029] In the present application, the bamboo preferably further comprises pre-treatment before use, and the pre-treatment preferably comprises one or more of mechanical pre-treatment, microwave pre-treatment and biological pre-treatment. In the present application, the mechanical pre-treatment preferably comprises cutting, crushing and grinding; the purpose of the mechanical pre-treatment is to keep the initial shape of the bamboo consistent, destroy the macrostructure of the bamboo, and expose more cell wall micropores. The use of ultrasonic pre-treatment, biological pre-treatment and microwave pre-treatment in the present application can further reduce the explosion temperature of the bamboo fiber in the subsequent steam explosion process, save energy and reduce consumption, and also reduce the damage to the bamboo fiber.
[0030] In the present application, the microwave treatment preferably comprises sequentially performing low-power microwave preheating treatment, medium-power microwave penetration treatment and high-power microwave strengthening treatment; the atmosphere of the microwave treatment preferably comprises air or a protective atmosphere, and the protective atmosphere preferably comprises nitrogen, argon or helium. In the present application, the power of the low-power microwave preheating treatment is preferably 200-600 W, more preferably 300-500 W, and can be specifically 200 W, 300 W, 350 W, 400 W, 500 W, 550 W or 600 W; the time of the low-power microwave preheating treatment is preferably 4-12 min, more preferably 8-10 min, and can be specifically 4 min, 6 min, 8 min, 10 min, 11 min or 12 min; after the low-power microwave preheating treatment, the temperature inside the bamboo material rises to 50-100℃, more preferably 70-90℃, and can be specifically 50℃, 60℃, 70℃, 80℃, 85℃, 90℃, 95℃ or 100℃. In the present application, the power of the medium-power microwave penetration treatment is preferably 600-800 W, more preferably 650-750 W, and can be specifically 600 W, 650 W, 700 W, 750 W or 800 W; the time of the medium-power microwave penetration treatment is preferably 5-8 min, and can be specifically 5 min, 6 min, 7 min or 8 min; after the medium-power microwave penetration treatment, the temperature inside the bamboo material rises to 100-120℃, and can be specifically 100℃, 105℃, 110℃, 115℃ or 120℃. In the present application, the power of the high-power microwave strengthening treatment is preferably 500-1000 W, more preferably 700-900 W, and can be specifically 500 W, 600 W, 700 W, 800 W, 900 W, 950 W or 1000 W; the time of the high-power microwave strengthening treatment is preferably 1-5 min, and can be specifically 1 min, 2 min, 3 min, 4 min or 5 min; after the high-power microwave strengthening treatment, the temperature inside the bamboo material rises to 100-150℃, more preferably 120-140℃, and can be specifically 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃. The present application realizes preliminary softening of lignin through low-power microwave preheating treatment, promotes separation of cellulose microfibrils through medium-power microwave penetration treatment, and instantaneously destroys cell wall structure through high-power microwave strengthening treatment; under the synergistic effect of the above microwave treatment conditions, the present application is beneficial to bamboo fibers with controllable morphology, excellent mechanical properties, sound absorption and noise reduction capacity.
[0031] After the microwave treatment, the bamboo material is preferably cooled to below 40℃, and then dried. In the present application, the cooling method preferably comprises air cooling, and the present application can avoid the bamboo fiber from being brittle due to residual heat. In the present application, the drying temperature is preferably 35-100℃, more preferably 60-100℃, and can be specifically 35℃, 40℃, 50℃, 60℃, 60℃, 75℃, 80℃, 90℃, 95℃ or 100℃; the drying time is preferably 4-48h, more preferably 8-20h, and can be specifically 4h, 8h, 12h, 16h, 20h, 25h, 30h, 35h, 40h or 45h; and the present application can reduce the water content to 0-3wt% through drying, which can be specifically 0wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% or 3wt%.
[0032] In the present application, the biological pretreatment preferably comprises one or both of enzyme pretreatment and bacteria pretreatment.
[0033] In the present application, the enzyme solution used in the enzyme treatment preferably comprises biological enzymes and water, and the biological enzymes preferably comprise one or more of hemicellulase, cellulase, xylanase, pectinase and ligninase; the ratio of the activity of the enzyme solution to the dry weight of the bamboo material is preferably 5-40IU / g, and can be specifically 5IU / g, 8IU / g, 10IU / g, 15IU / g, 20IU / g, 25IU / g, 30IU / g, 35IU / g or 40IU / g; when the biological enzymes in the enzyme solution are single enzymes, the ratio of the activity of the enzyme solution to the dry weight of the bamboo material is more preferably 5-30IU / g; and when the biological enzymes in the enzyme solution are complex enzymes with two or more kinds, the ratio of the activity of the enzyme solution to the dry weight of the bamboo material is more preferably 8-40IU / g. In the present application, the pH value of the enzyme solution is preferably 5.5-8, and can be specifically 5.5, 6, 6.5, 7, 7.5 or 8.
[0034] In the present application, the temperature of the enzyme treatment is preferably 30-60℃, and can be specifically 30℃, 35℃, 40℃, 45℃, 50℃, 55℃ or 60℃; and the time of the enzyme treatment is preferably 2-72h, more preferably 5-40h, and can be specifically 2h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h or 72h. The present application can perform enzyme treatment under the above conditions, has high enzyme activity, high treatment efficiency, can remove non-cellulose impurities in a targeted manner, purify fibers, and has good treatment effect.
[0035] In the present application, the enzyme treatment preferably comprises at least one of pressurized spraying and vacuum impregnation. In the present application, the pressurized spraying preferably comprises sequentially performing low-pressure spraying and medium-pressure spraying; the pressure of the low-pressure spraying is preferably 0.1-0.4 MPa, and can be specifically 0.1 MPa, 0.2 MPa, 0.3 MPa or 0.4 MPa; the time of the low-pressure spraying is preferably 0.5-8 h, and more preferably 1-3 h, and can be specifically 0.5 h, 1 h, 2 h, 3 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h or 8 h; the pressure of the medium-pressure spraying is preferably 0.5-2 MPa, and can be specifically 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa or 2 MPa; the time of the medium-pressure spraying is preferably 0.3-6 h, and more preferably 0.5-2 h, and can be specifically 0.3 h, 0.5 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h. In the present application, the vacuum degree of the vacuum impregnation is preferably -0.08--0.095 MPa, and can be specifically -0.08 MPa, -0.085 MPa, -0.09 MPa, -0.092 MPa or -0.095 MPa.
[0036] In the present application, the bacteria used in the bacteria treatment preferably comprise one or more of white rot fungi, brown rot fungi and soft rot fungi. In the present application, the temperature of the bacteria treatment is preferably 30-55℃, and can be specifically 30℃, 32℃, 35℃, 37℃, 40℃, 45℃, 50℃ or 55℃; the time of the bacteria treatment is preferably 0.3-72 h, and more preferably 20-60 h, and can be specifically 0.3 h, 2 h, 5 h, 10 h, 12 h, 15 h, 20 h, 24 h, 30 h, 35 h, 40 h, 45 h, 48 h, 50 h, 55 h, 60 h, 65 h, 70 h or 72 h.
[0037] The existing enzyme treatment and bacteria treatment have problems of low treatment efficiency and insufficient specificity of enzymes. The biological enzyme used in the present application only acts on lignin, pectin and hemicellulose in bamboo, does not destroy the core cellulose of the target component, i.e. bamboo fiber, has strong enzyme specificity, and controls the enzyme treatment and bacteria treatment conditions, thereby greatly improving the efficiency of biological treatment.
[0038] In the present application, the physical crushing opening fiber treatment crushing gap is preferably 1-8 mm, more preferably 2-6 mm, which can be specifically 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm; the physical crushing opening fiber treatment crushing times is preferably 1-20 times, more preferably 5-10 times, which can be specifically 1 time, 3 times, 5 times, 8 times, 10 times, 12 times, 15 times, 18 times or 20 times. The present application can reduce the explosion temperature of bamboo fiber in the subsequent steam explosion process, save energy and reduce consumption, and also reduce the damage to bamboo fiber by physical crushing opening fiber treatment of bamboo.
[0039] After the physical crushing opening fiber treatment, the present application preferably further includes rubbing and sorting to obtain short fibers (length < 25 mm), medium bamboo fibers (length 25-40 mm) and long fibers (length > 40 mm). In the present application, the rubbing and sorting pressure is preferably 0.1-0.8 MPa, more preferably 0.2-0.5 MPa, which can be specifically 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa or 0.8 MPa; the rubbing and sorting time is preferably 0.5-15 min, more preferably 1-10 min, which can be specifically 0.5 min, 1 min, 3 min, 5 min, 6 min, 8 min, 10 min, 12 min or 15 min; the rubbing and sorting speed is preferably 400-1200 r / min, which can be specifically 400 r / min, 600 r / min, 800 r / min, 1000 r / min or 1200 r / min; the rubbing and sorting is preferably carried out by rubbing machine, which can be specifically carried out by bamboo fiber rubbing machine. The rubbing and sorting of the present application can realize the continuous production of bamboo fiber belt.
[0040] In the present application, the chemical composition of the alkaline solution preferably comprises an alkaline reagent, an auxiliary agent and water; the pH value of the alkaline solution is preferably 8-12, which can be specifically 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12. In the present application, the mass concentration of the alkaline reagent in the alkaline solution is preferably 1-8%, which can be specifically 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%. In the present application, the alkaline reagent preferably comprises one or more of alkali metal carbonate, alkali metal bicarbonate, alkali metal percarbonate, alkali metal hydroxide and wood ash, which can be specifically one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium percarbonate, potassium percarbonate, sodium hydroxide, potassium hydroxide and wood ash. In the present application, the mass concentration of the auxiliary agent in the alkaline solution is preferably 0.05-0.3%, which can be specifically 0.05%, 0.1%, 0.2% or 0.3%. In the present application, the auxiliary agent preferably comprises one or more of a chelating agent, an alkali-resistant penetrant, a buffering agent, a dispersing agent and a defoaming agent. In the present application, the chelating agent preferably comprises one or more of diethylenetriamine pentaacetic acid penta sodium, amino-tris-methylene phosphonic acid and hydroxyethylidene diphosphonic acid disodium, and the mass concentration of the chelating agent in the alkaline solution is preferably 0.05-0.3%, which can be specifically 0.05%, 0.1%, 0.2% or 0.3%. In the present application, the alkali-resistant penetrant preferably comprises one or more of alkali-resistant penetrants JFC, AEP and OEP-70; and the mass concentration of the alkali-resistant penetrant in the alkaline solution is preferably 0.1-0.5%, which can be specifically 0.1%, 0.2%, 0.3%, 0.4% or 0.5%. In the present application, the buffering agent preferably comprises one or more of a mixture of disodium hydrogen phosphate and sodium dihydrogen phosphate, a mixture of sodium citrate and sodium hydroxide, and a mixture of aminoethanol and sodium hydroxide; and the mass concentration of the buffering agent in the alkaline solution is preferably 0.02-0.1%, which can be specifically 0.02%, 0.05%, 0.08% or 0.1%. In the present application, the dispersing agent preferably comprises one or more of sodium polyacrylate, sodium polyacrylate and naphthalene sulfonate formaldehyde condensate; and the mass concentration of the dispersing agent in the alkaline solution is preferably 0.03-0.2%, which can be specifically 0.03%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.2%. In the present application, the defoaming agent preferably comprises one or more of dimethyl silicone oil defoaming agent, polyether modified silicone oil defoaming agent and polyoxypropylene glycerol ether defoaming agent; and the mass concentration of the defoaming agent in the alkaline solution is preferably 0.01-0.05%, which can be specifically 0.01%, 0.02%, 0.03%, 0.04% or 0.05%.The application does not have special limitation for the amount of the alkali liquor, and the bamboo material can be immersed in the alkali liquor, and specifically, the ratio of the dry weight of the bamboo material to the volume of the alkali liquor is preferably 1 kg:5-20 L, more preferably 1 kg:5 L, 1 kg:8 L, 1 kg:10 L, 1 kg:12 L, 1 kg:15 L, 1 kg:18 L or 1 kg:20 L.
[0041] In the application, the temperature of the alkali liquor soaking is preferably 25-100 ℃, more preferably 50-90 ℃, and can be specifically 25 ℃, 30 ℃, 40 ℃, 50 ℃, 55 ℃, 60 ℃, 70 ℃, 80 ℃, 85 ℃, 90 ℃ or 100 ℃; the time of the alkali liquor soaking is preferably 0.5-72 h, and can be specifically 0.5 h, 1 h, 2 h, 3 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 50 h, 55 h, 60 h, 65 h, 70 h or 72 h. The application is beneficial to the separation of lignin and cellulose through alkali liquor soaking.
[0042] After the alkali liquor soaking is completed, the application preferably further comprises neutralizing the residual alkali of the fiber obtained through the alkali liquor soaking to pH 6-7. In the application, the neutralization preferably comprises soaking with an acetic acid-citric acid solution; the mass concentration of the acetic acid-citric acid solution is preferably 0.5-1%, more preferably 0.6-0.8%, and can be specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%; the time of the soaking is preferably 1-48 h, more preferably 2-10 h, and can be specifically 1 h, 2 h, 5 h, 10 h, 15 h, 20 h, 24 h, 30 h, 35 h, 38 h, 40 h, 45 h or 48 h. In the application, the pH value can be specifically 6, 6.2, 6.4, 6.6, 6.8 or 7. The alkali liquor used in the application has significant environmental friendly characteristics and small wastewater production, and the process and drug content required for the post-treatment (neutralization of residual alkali) are small, which reduces the environmental pressure.
[0043] In the application, the conditions of the enzyme treatment are preferably the same as those of the enzyme pretreatment, which are not described herein again. In the application, the conditions of the bacteria treatment are preferably the same as those of the bacteria pretreatment, which are not described herein again.
[0044] After the combined treatment fiber is obtained, the application carries out steam explosion treatment on the combined treatment fiber to obtain bamboo fiber with controllable morphology.
[0045] In the present application, the ratio of dry weight of bamboo to volume of water in the steam explosion treatment is 1-4 kg:1 L, which can be specifically 1 kg:1 L, 1.5 kg:1 L, 2 kg:1 L, 2.5 kg:1 L, 3 kg:1 L, 3.5 kg:1 L or 4 kg:1 L. In the present application, the conditions of the steam explosion treatment preferably include: the explosion temperature is 110-200℃, which can be specifically 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃; the explosion pressure is 1-3 MPa, more preferably 1.5-2 MPa, which can be specifically 1 MPa, 1.5 MPa, 1.8 MPa, 1.9 MPa, 2 MPa, 2.1 MPa, 2.4 MPa, 2.6 MPa, 2.8 MPa or 3 MPa; the explosion time is 2-8 min, more preferably 3-5 min, which can be specifically 2 min, 3 min, 4 min, 5 min, 6 min, 7 min or 8 min; and the pressure relief speed is 0.1-10 MPa / s, more preferably 0.5-5 MPa / s, which can be specifically 0.1 MPa / s, 0.5 MPa / s, 1 MPa / s, 2 MPa / s, 3 MPa / s, 4 MPa / s, 5 MPa / s, 6 MPa / s, 7 MPa / s, 8 MPa / s, 9 MPa / s or 10 MPa / s. The present application determines the dissociation intensity and uniformity of fibers by precisely regulating the three parameters of steam pressure, pressure holding time and pressure relief speed, thereby realizing the directional control of fiber morphology (length, diameter, dispersity) and achieving the effect of preparing morphology-controllable bamboo fibers. The present application can reduce the damage of bamboo fibers by carrying out rapid steam explosion treatment under the above low-temperature and low-pressure conditions.
[0046] After the steam explosion treatment is completed, the present application preferably further includes: solid-liquid separation, fiber sorting of the obtained solid fibers or sequentially carrying out biological uniformization treatment and fiber sorting to obtain morphology-controllable bamboo fibers. In the present application, the solid-liquid separation is preferably carried out in a separation tower, and feeding and discharging are carried out at the same time. Bamboo fibers are separated in the upper layer, and filtrate is collected in the lower layer and treated as liquid fertilizer. In the present application, the fiber sorting preferably utilizes a fiber sorting machine to sort and classify bamboo fibers. In the present application, the biological uniformization treatment preferably includes at least one of enzyme uniformization treatment and fungus uniformization treatment. In the present application, the conditions of the enzyme uniformization treatment are preferably the same as those of the enzyme pretreatment, which will not be repeated here. In the present application, the conditions of the fungus uniformization treatment are preferably the same as those of the fungus pretreatment, which will not be repeated here.
[0047] In the present application, the steam explosion treatment preferably comprises at least one of continuous steam explosion treatment and intermittent steam explosion treatment. In the present application, the continuous steam explosion treatment preferably comprises continuously performing 2-4 (more preferably 3) steam explosion treatments, and after each steam explosion treatment, fiber sorting is preferably performed first, and then the next steam explosion treatment is performed. In the present application, the number of steam explosion treatments is preferably the same as the number of cavities in the device used. In the present application, taking 3 serial cavities as an example, the steam explosion treatment preferably comprises the following steps: using a device with 3 serial cavities for continuous steam explosion treatment, feeding the joint processed bamboo into the first cavity for first steam explosion and fiber sorting to obtain bamboo fibers meeting the requirements and residual fibers, feeding the residual fibers into the second cavity for second steam explosion and fiber sorting to obtain bamboo fibers meeting the length requirements and residual fibers, and feeding the residual fibers into the third cavity for third steam explosion and fiber sorting to obtain controllable bamboo fibers. In the present application, the feeding is preferably performed by a screw. The present application can realize the preparation of bamboo fibers with different forms by using continuous steam explosion treatment, and the energy consumption is low. In the present application, the fiber sorting is preferably performed by using a fiber sorting machine to sort and classify the bamboo fibers. In the present application, the joint processed bamboo is sorted before steam explosion treatment, and steam explosion treatment is performed in batches. After each steam explosion treatment, the exploded bamboo fibers are sorted, the pressure and temperature of the steam explosion are adjusted, and the residual bamboo is subjected to steam explosion treatment again. This process is repeated until the steam explosion treatment is completed. After the steam explosion treatment is completed, post-treatment (fiber sorting or first biological homogenization and then fiber sorting) is performed. The sorting process uses a bamboo fiber sorting machine to sort and classify bamboo fibers of different lengths. Through staged steam explosion and multiple fiber sorting, controllable bamboo fibers can be obtained.
[0048] In the present application, when 2 steam explosion treatments are continuously performed, the first steam explosion treatment preferably has a pressure of 1.25 MPa, a holding temperature of 180℃, and a holding time of 4 min, and the second steam explosion treatment preferably has a pressure of 2.5 MPa, a holding temperature of 210℃, and a holding time of 3 min.
[0049] In the present application, when 3 steam explosion treatments are continuously performed, the first steam explosion treatment preferably has a pressure of 0.8 MPa, a holding temperature of 160℃, and a holding time of 5 min, the second steam explosion treatment preferably has a pressure of 2 MPa, a holding temperature of 190℃, and a holding time of 3 min, and the third steam explosion treatment preferably has a pressure of 0.5 MPa, a holding temperature of 120℃, and a holding time of 2 min.
[0050] In the present application, when the steam explosion treatment is continuously performed 4 times, the conditions of the first steam explosion treatment preferably include: a pressure of 0.6 MPa, a pressure maintaining temperature of 150°C, and a pressure maintaining time of 8 min; the conditions of the second steam explosion treatment preferably include: a pressure of 2.5 MPa, a pressure maintaining temperature of 230°C, and a pressure maintaining time of 1 min; the conditions of the third steam explosion treatment preferably include: a pressure of 1.2 MPa, a pressure maintaining temperature of 180°C, and a pressure maintaining time of 4 min; and the conditions of the fourth steam explosion treatment preferably include: a pressure of 0.3 MPa, a pressure maintaining temperature of 100°C, and a pressure maintaining time of 1 min.
[0051] In the present application, the conditions of the intermittent steam explosion treatment preferably include: a temperature of the pre-steam cavity of 120-150°C, which can be specifically 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C; a pressure of 0.1-1.5 MPa, more preferably 0.5-1 MPa, which can be specifically 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.85 MPa, 0.9 MPa, 0.95 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, or 1.5 MPa; a temperature of the main explosion cavity of 150-210°C, more preferably 180-200°C, which can be specifically 150°C, 165°C, 170°C, 180°C, 190°C, 195°C, 200°C, 205°C, or 210°C; a pressure of the main explosion cavity of 1.5-3.5 MPa, more preferably 2-3 MPa, which can be specifically 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, or 3.5 MPa; a pressure maintaining time of the main explosion cavity of 30-200 seconds (s), more preferably 60-150 s, which can be specifically 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 120 s, 150 s, 160 s, 180 s, or 200 s; a temperature of the cooling cavity of 50-100°C, more preferably 70-90°C, which can be specifically 50°C, 60°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C; and a pressure of the cooling cavity of 0.1-0.8 MPa, more preferably 0.2-0.5 MPa, which can be specifically 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, or 0.8 MPa.
[0052] After the steam explosion treatment, the application preferably further comprises: solid-liquid separation, fiber sorting of the obtained solid fibers, or biological homogenization treatment and fiber sorting in sequence, to obtain form-controllable bamboo fibers.
[0053] In the application, the biological homogenization treatment preferably comprises at least one of enzyme homogenization treatment and bacteria homogenization treatment.
[0054] The application also provides form-controllable bamboo fibers prepared by the preparation method, which comprise one or more of short bamboo fibers, medium-length bamboo fibers and long bamboo fibers; the length of the short bamboo fibers is < 25 mm; the length of the medium-length bamboo fibers is 25-40 mm; and the length of the long bamboo fibers is > 40 mm.
[0055] The application also provides application of the form-controllable bamboo fibers as fillers of organic materials or inorganic materials.
[0056] The long bamboo fibers provided by the application have long length and good toughness, can be used as material anchorage, increase the tensile strength, bending strength, shear strength and other properties of the material, and increase the use durability of the material; can also be used for manufacturing high-performance composite materials and technical yarns, and are sustainable substitutes for carbon fibers and glass fibers; and can also be used for high-end textiles, and can be used for weaving soft and breathable clothes and home textiles, and endow the products with high-end texture.
[0057] The medium bamboo fibers provided by the application have moderate length and good comprehensive performance, can be used for producing garment fabrics, for spinning yarns with medium thickness, or for knitting and non-woven fabrics that require a certain length and strength, and have strength, hand feeling and processing convenience; and can also be used as reinforcing or filling fibers for cement boards, thermal insulation materials, sound-absorbing materials and flame-retardant materials and other building materials, to improve the bending resistance, crack resistance, thermal insulation, sound-absorbing performance and other properties of the materials.
[0058] The short bamboo fiber provided by this invention, with its cost and natural properties, can be used to produce foam materials, paper, fillers, and fiber blends. It can improve the toughness and antibacterial properties of paper products, provide moisture-absorbing and antibacterial functions for fillers, and enhance product functionality and cost-effectiveness when blended. It can also be used as a sandwich material for automotive interiors, providing sound absorption and flame retardancy. Short bamboo fiber can also be used in blended fabrics or combined with other materials for applications such as 3D printing, non-woven mats, and injection molding compounds.
[0059] To further illustrate the present invention, the following detailed description of the morphology-controllable bamboo fiber, its preparation method, and its application, in conjunction with embodiments, is provided but should not be construed as limiting the scope of protection of the present invention.
[0060] In the following examples, the bamboo is cut into 1-10cm lengths and then cleaned before use.
[0061] Example 1 according to Figure 1 The process flow diagram shown illustrates the preparation of bamboo fiber with controllable morphology.
[0062] Physical rolling and fiber splitting treatment: Put the bamboo into a roller rolling and fiber splitting machine for physical rolling and fiber splitting treatment (rolling gap is 2mm) 15 times to obtain split bamboo material.
[0063] Preparation of alkaline solution: Add 70kg distilled water, 1.6kg sodium percarbonate, 210g pentasodium diethylenetriaminepentaacetate, 350mL alkali-resistant penetrant JFC, 210mL buffer (a mixed aqueous solution of disodium hydrogen phosphate and sodium dihydrogen phosphate), 350g sodium polyacrylate, and 210mL dimethyl silicone oil defoamer, and stir until completely dissolved.
[0064] Alkali soaking: Add the treated bamboo to the alkali solution according to the ratio of dry weight of bamboo to volume of alkali solution = 1kg: 10L, press the split bamboo to completely immerse it in the alkali solution, boil it at 90℃ for 80 minutes, take out the bamboo and get the co-treated fiber.
[0065] Continuous steam explosion treatment: The combined-processed fibers are fed into a steam explosion machine for continuous steam explosion treatment. The pressure is released for 1-5 seconds, and the material is collected to obtain steam-exploded bamboo fiber. The conditions for steam explosion treatment are as follows: the ratio of dry weight of bamboo to water volume is 2 kg: 1 L, the explosion pressure is 2 MPa, the pressure holding time is 4 min, and the pressure release rate is 4 MPa / s.
[0066] Defibration: Defibrate the steam exploded bamboo fibers using a fiber sorting machine, wash to neutral, dry to constant weight, and obtain long bamboo fibers (length greater than 40 mm), medium bamboo fibers (length of 25-40 mm), and short bamboo fibers (length less than 25 mm), respectively. The yield of the morphologically controllable bamboo fibers is 55%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers is 32%.
[0067] Example 2 Physical rolling and defibration treatment: Put the moso bamboo into a rolling and defibration machine for physical rolling and defibration treatment (rolling gap is 2 m) for 10 times to obtain the defibrated bamboo.
[0068] Microwave treatment: First, preheat for 12 min at a low power of 16 kW to gradually increase the internal temperature of the bamboo to 70°C, so as to preliminarily soften the lignin; then switch to a medium power of 25 kW for 7 min of penetration treatment to further increase the temperature to 100°C, so as to promote the separation of cellulose microfibers; finally, use a high power of 65 kW for 1 min of intensified treatment to suddenly increase the internal temperature of the bamboo to 140°C, so as to instantaneously destroy the cell wall structure. After the microwave treatment, the bamboo needs to be immediately air-cooled to quickly reduce the temperature to below 40°C, so as to avoid the fiber from being brittle due to residual heat, and then dried at 80°C for 2 h to adjust the moisture content of the bamboo to 8%.
[0069] Continuous steam explosion treatment: Put the joint treatment fibers into a steam explosion machine for steam explosion treatment, release pressure, collect the materials, defibrate, and dry to constant weight to obtain morphologically controllable bamboo fibers (long bamboo fibers (length greater than 40 mm), medium bamboo fibers (length of 25-40 mm), and short bamboo fibers (length less than 25 mm), the yield of the morphologically controllable bamboo fibers is 50%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers is 28%. The conditions of the continuous steam explosion treatment are as follows: the ratio of the dry weight of the bamboo to the volume of water is 3 kg: 1 L, the explosion pressure is 1.8 MPa, the pressure holding time is 3 min, and the pressure release speed is 5 MPa / s.
[0070] Example 3 Physical rolling and defibration treatment: Put the moso bamboo into a rolling and defibration machine for physical rolling and defibration treatment (rolling gap is 3 m) for 20 times to obtain the defibrated bamboo.
[0071] Preparation of enzyme solution: Mix xylanase solution and cellulase solution at a mass ratio of 1:2, and then mix the obtained mixed enzyme with finishing water to obtain an enzyme solution with a biological enzyme concentration of 15 g / L.
[0072] By means of pressurized spraying, spray the enzyme solution (pressure is 1.2 MPa) on the defibrated bamboo, and then ferment in a sealed environment at 50°C for 24 h to obtain joint treatment fibers. The ratio of the dry weight of the bamboo to the volume of the enzyme solution is 1 kg: 1.5 L.
[0073] Intermittent steam explosion treatment: the combined processing fibers were put into a steam explosion machine for intermittent steam explosion treatment, the materials were collected, fibrillated, and dried to constant weight, respectively obtaining long bamboo fibers (length greater than 40 mm), medium bamboo fibers (length of 25-40 mm) and short bamboo fibers (length less than 25 mm), the yield of the morphologically controllable fibers was 48%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers was 30%. The conditions of the intermittent steam explosion treatment were as follows: the temperature of the pre-steaming cavity was 130°C, the pressure was 0.6 MPa; the temperature of the main explosion cavity was 190°C, the pressure was 1.8 MPa (pressure maintaining for 80 seconds); the temperature of the cooling cavity was 90°C, the pressure was 0.2 MPa; the pressure relief speed was 6 MPa / s. The ratio of the dry weight of the bamboo to the volume of water was 3 kg: 1 L, the explosion pressure was 2.5 MPa, and the pressure maintaining time was 4 min.
[0074] Comparative Example 1 Alkali soaking: 100 g (dry weight) of 20-40 mesh bamboo powder was mixed with 1 wt% sodium hydroxide solution at a solid-liquid ratio of 1 g:20 mL, and reacted at 80°C for 2 h; after the reaction, the slurry was filtered, washed with water until neutral, and the pH value of the slurry was adjusted to 4.5 with dilute acetic acid to obtain chemically pretreated bamboo residue.
[0075] Laccase treatment: to the chemically pretreated bamboo residue, an acetic acid-sodium acetate buffer solution with pH=4.5 was added to maintain a solid-liquid ratio of 1 g:15 mL, and laccase was added in an amount of 50 U / g substrate, and the enzyme hydrolysis was carried out at 50°C and 150 r / min for 24 h; after the enzyme hydrolysis, the enzyme was inactivated by boiling water bath, the slurry was filtered, washed with water and dried to obtain biologically pretreated bamboo residue.
[0076] Steam explosion: the biologically pretreated bamboo residue was moistened to a moisture content of 55%, and was placed in a steam explosion device, and was maintained at a saturated steam pressure of 1.5 MPa for 4 min, and then was instantaneously pressure released to realize fiber separation, and finally a fiber sorting machine was used to separate the steam exploded bamboo fibers, and the fibers were washed to neutral and dried to constant weight, respectively obtaining long bamboo fibers (length greater than 40 mm), medium bamboo fibers (length of 25-40 mm) and short bamboo fibers (length less than 25 mm), the yield of the morphologically controllable bamboo fibers was 30%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers was 18%.
[0077] Example 4 Physical rolling and fibrillation treatment: the moso bamboo was put into a rolling and fibrillation machine for physical rolling and fibrillation treatment (rolling gap was 2 mm) for 15 times to obtain the fibrillated bamboo.
[0078] Preparation of the lye: 70 kg of distilled water, 3.7 kg of wood ash, 210 g of diethylene triamine pentaacetic acid penta sodium, 350 mL of alkali-resistant penetrant JFC, 210 mL of buffer (mixed aqueous solution of sodium phosphate dibasic and sodium phosphate monobasic), 350 g of sodium polyacrylate, and 210 mL of dimethyl silicone oil defoaming agent were stirred until completely dissolved.
[0079] Lye soaking: The treated bamboo was added to the lye according to a bamboo dry weight to lye volume ratio of 1 kg: 10 L, the bamboo was pressed to open the fibers and completely immersed in the lye, and the bamboo was cooked at 90°C for 60 min. The treated bamboo was then removed to obtain the combined treated fibers.
[0080] Continuous steam explosion treatment: The combined treated fibers were fed into a steam explosion machine for continuous steam explosion treatment, the pressure was released for 1-5 s, and the material was collected to obtain the steam exploded bamboo fibers. The steam explosion treatment was performed at a bamboo dry weight to water volume ratio of 2 kg: 1 L, a pressure of 2 MPa, a pressure holding time of 4 min, and a pressure release rate of 7 MPa / s.
[0081] Fiber separation: The steam exploded bamboo fibers were separated using a fiber sorting machine, washed with water to neutralize, and dried to constant weight to obtain long bamboo fibers (length greater than 40 mm), medium bamboo fibers (length of 25-40 mm), and short bamboo fibers (length less than 25 mm). The yield of the morphologically controllable bamboo fibers was 45%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers was 29%.
[0082] Example 5 BF (bamboo fibers) and PP (polypropylene) were dried in an oven at 103°C until the water content was less than 2 wt%. The BF and PP particles were mixed uniformly in a high-speed mixer according to the ratio, and then the mixture was extruded and pelletized by a twin-screw extruder. The extrusion three-section temperatures were 165°C, 170°C, and 172°C, respectively. Finally, the above pellets were used to prepare a BF reinforced PP composite material by an injection molding machine at 180°C. The BF was long bamboo fibers, medium bamboo fibers, short bamboo fibers prepared in Examples 1-4, and bamboo fibers prepared in Comparative Example 1. The mass content of the BF in the BF reinforced PP composite material was 20%, and the mass content of the long bamboo fibers in the morphologically controllable bamboo fibers was 33%.
[0083] Test Example 1 The performance test was performed according to GB / T 1040.5-2006. The tensile strength of the morphologically controllable bamboo fibers was tested by a mechanical testing machine.
[0084] The sound absorption coefficient and the noise reduction coefficient of the BF reinforced PP composite material were measured by an impedance tube test system. The bamboo fibers in the BF reinforced PP composite material were short bamboo fibers.
[0085] The horizontal burning speed of the BF reinforced PP composite material is obtained by the vertical burning test, wherein the bamboo fiber in the BF reinforced PP composite material is short bamboo fiber.
[0086] The test results are shown in Table 1.
[0087] Table 1 Performance test results of the shape-controllable bamboo fiber and the BF reinforced PP composite material
[0088] As shown in Table 1, the bamboo fiber prepared by the pretreatment combined with the steam explosion is shape-controllable; the tensile strength of the long, medium and short bamboo fibers is 560-580 MPa, 527-542 MPa and 430-450 MPa respectively; the elongation at break of the long, medium and short bamboo fibers is 15-19%, 17-18% and 16-19% respectively; the sound absorption coefficient of the BF reinforced PP composite material is 0.213-0.234, the noise reduction coefficient is 0.165-0.712, and the horizontal burning speed is 13-15 mm / min, which indicates that the shape-controllable bamboo fiber prepared by the present application has high mechanical properties, excellent sound absorption and noise reduction performance, and has flame retardant performance, and has higher comprehensive performance and higher purity. The shape-controllable bamboo fiber prepared in Comparative Example 1 has poor strength and toughness, the average length of the fiber is shortened, and the proportion of the long bamboo fiber is reduced.
[0089] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method for preparing morphology-controllable bamboo fiber, characterized in that, Includes the following steps: Bamboo is subjected to a combined treatment to obtain combined-treated bamboo; the combined treatment includes physical compaction and fiber splitting treatment and chemical / biological treatment, the chemical / biological treatment including at least one of alkaline soaking, enzyme treatment and fungal treatment; the physical compaction and fiber splitting treatment and the chemical / biological treatment have no temporal order. The combined-processed bamboo material is subjected to steam explosion treatment to obtain bamboo fiber with controllable morphology. The conditions for the steam explosion treatment include: an explosion temperature of 110~200℃, an explosion pressure of 1~3MPa, an explosion time of 2~8min, and a pressure relief rate of 0.1~10MPa / s.
2. The preparation method according to claim 1, characterized in that, The compaction gap of the physical compaction fiber opening treatment is 1~4mm, and the number of compaction cycles is 1~20. The physical crushing and fiber opening process also includes kneading and sorting.
3. The preparation method according to claim 1, characterized in that, The bamboo material is further subjected to pretreatment before use, and the pretreatment preferably includes one or more of microwave pretreatment, ultrasonic pretreatment and biological pretreatment.
4. The preparation method according to claim 1, characterized in that, The alkaline solution used for the immersion has a chemical composition including alkaline reagents, additives, and water; the additives include one or more of chelating agents, alkali-resistant penetrants, buffers, dispersants, and defoamers; the pH value of the alkaline solution is 8-12. The alkaline solution soaking temperature is 25~100℃, and the time is 0.5~72h.
5. The preparation method according to claim 1, characterized in that, The enzyme solution used in the enzyme treatment includes biological enzymes and water. The biological enzymes include one or more of hemicellulase, cellulase, xylanase, pectinase, and ligninase. The pH value of the enzyme solution is 5.5-8. The ratio of the enzyme activity to the dry weight of the bamboo is 5~40 IU / g; The enzyme treatment is carried out at a temperature of 30~60℃ for a time of 2~72h; The enzyme treatment includes at least one of pressurized spraying and vacuum impregnation; the pressurized spraying includes sequential low-pressure spraying and medium-pressure spraying, wherein the low-pressure spraying pressure is 0.1~0.4MPa and the time is 0.5~8h; and the medium-pressure spraying pressure is 0.5~2MPa and the time is 0.3~6h.
6. The preparation method according to claim 1, characterized in that, The bacteria used in the bacterial treatment include one or more of white rot fungi, brown rot fungi, and soft rot fungi. The bacterial treatment was carried out at a temperature of 30-55°C for 0.3-72 hours.
7. The preparation method according to claim 1, characterized in that, During the steam explosion treatment, the dry weight of the bamboo to the volume of water is 1-4 kg: 1 L. The steam explosion treatment includes at least one of continuous steam explosion treatment and intermittent steam explosion treatment.
8. The preparation method according to claim 1 or 7, characterized in that, The steam explosion treatment further includes: solid-liquid separation, and fiber sorting of the obtained solid fibers or sequential biological homogenization treatment and fiber sorting.
9. The morphology-controllable bamboo fiber prepared by the preparation method according to any one of claims 1 to 8, characterized in that, Including one or more of short bamboo fiber, medium-length bamboo fiber and long bamboo fiber; The length of the short bamboo fiber is <25mm; The length of the bamboo fiber is 25~40mm; The length of the bamboo fiber is >40mm.
10. The application of the morphology-controllable bamboo fiber as described in claim 9 as a filler for organic or inorganic materials.