Continuous bamboo fiber preparation method

Abstract

The invention discloses a continuous bamboo fiber preparation method, and belongs to the technical field of bamboo fiber preparation. The blasted bamboo wood is subjected to enzymolysis; the bamboo wood subjected to enzymolysis is conveyed into a separator to be continuously separated, and fiber bundles are obtained; preparing a fiber suspension from the fiber bundles, and screening to obtain purified fiber bundles; the purified fiber bundles are drafted; freezing the drafted fiber bundles, then unfreezing the fiber bundles, and then drying the fiber bundles to obtain the continuous bamboo fibers. By adopting the continuous bamboo fiber preparation method disclosed by the invention, the bamboo fibers with excellent performance, high purity and good uniformity can be prepared, the problems of poor fiber quality, insufficient stability and the like existing in a traditional method are effectively solved, the production efficiency can be improved, the environmental pollution and energy consumption are reduced, the production cost is reduced, and the method is suitable for industrial production. And high performance, continuity and green economy are considered.

Description

Technical Field

[0001] The invention relates to the technical field of bamboo fiber preparation, in particular to a method for preparing continuous bamboo fiber. Background Art

[0002] Bamboo fiber, a green and environmentally friendly material derived from a natural, renewable resource, boasts excellent properties such as high strength, good breathability, and biodegradability, showing broad application prospects in textiles, composite materials, and papermaking. However, current bamboo fiber production technology still faces numerous challenges, hindering its large-scale production and high-end applications.

[0003] Traditional bamboo fiber production methods primarily include chemical and mechanical methods. Chemical methods, which treat bamboo with strong alkalis, strong acids, and other chemical reagents, effectively remove impurities such as lignin and hemicellulose. However, these methods pose significant environmental risks, significant fiber damage, and difficulty recovering the chemical reagents. Furthermore, the wastewater treatment costs generated during the production process are high, which is inconsistent with the development of green manufacturing. Mechanical methods, which often involve physical crushing and grinding to dissociate bamboo fibers, can reduce chemical pollution, but the resulting fiber bundles are larger in diameter, uneven in length, have a high lignin residue rate, and exhibit poor fiber properties, making them difficult to meet the demands of high-end applications for refined and high-performance fibers. Summary of the Invention

[0004] The purpose of the present invention is to provide a continuous bamboo fiber preparation method. Through the coordinated optimization and continuous design of each process step, bamboo fibers with excellent performance, high purity and good uniformity can be prepared, effectively solving the problems of poor fiber quality and insufficient stability existing in traditional methods, and improving production efficiency, reducing environmental pollution and energy consumption, and lowering production costs, taking into account high performance, continuity and green economy.

[0005] To achieve the above object, the present invention provides a method for preparing continuous bamboo fiber, comprising the following steps: S1, steam explosion of bamboo; S2, enzymatically hydrolyzing the exploded bamboo; S3, sending the enzymatically hydrolyzed bamboo material to a separator for continuous separation to obtain fiber bundles; S4, preparing the fiber bundle into a fiber suspension and screening it to obtain a purified fiber bundle; S5, drafting the purified fiber bundle; S6. Freezing the drawn fiber bundle and then thawing it, and then drying it to obtain continuous bamboo fibers.

[0006] Preferably, the specific operation of S1 is: selecting 3-4 year old bamboo, cutting the bamboo into 1-1.5 m lengths, removing bamboo nodes and surface impurities, placing the obtained bamboo segments in a steam explosion device, passing saturated steam, and then instantly reducing the pressure to room temperature to cause the bamboo segments to initially dissociate.

[0007] Preferably, in S1, the bamboo material is one of Phyllostachys pubescens, Phyllostachys pubescens, and Phyllostachys cirrhosa, the pressure of the saturated steam is 0.5-1 MPa, and the saturated steam is introduced for 80-100 seconds.

[0008] Preferably, the specific operation of S2 is: first preparing a composite enzymatic hydrolysis solution, then immersing the preliminarily dissociated bamboo into the composite enzymatic hydrolysis solution and stirring for enzymatic hydrolysis, after the enzymatic hydrolysis is completed, filtering to separate the enzymatically hydrolyzed bamboo and the enzymatic hydrolysis solution, and rinsing the separated enzymatically hydrolyzed bamboo with deionized water.

[0009] Preferably, in S2, the solid-liquid ratio of the composite enzymatic hydrolysis solution to the preliminarily dissociated bamboo is 1: (15-20), the composite enzymatic hydrolysis solution is a citric acid buffer with a pH of 4-5, the citric acid buffer contains xylanase, laccase and manganese peroxidase, the mass ratio of xylanase, laccase and manganese peroxidase is (1.5-2): 1: (0.5-0.8), the enzymatic hydrolysis temperature is 50-60 ° C, the enzymatic hydrolysis time is 2-3h, the stirring rate is 100-150r / min, and the number of rinsing times is 3-5 times.

[0010] Preferably, in S3, the separator is a rotary twin-screw separator having a length-to-diameter ratio of 40:1, a screw speed of 150-250 r / min, and a separator adopts three-stage temperature control and stepped pressure control. The feed zone is 80°C and 0.3 MPa, the main separation zone is 110°C and 15-20 MPa, and the discharge zone is 90°C and 0.5 MPa. Supercritical CO2 is injected into the main separation zone of the separator, and the injection amount of supercritical CO2 is 0.5-0.8 kg / kg of bamboo. The injection of supercritical CO2 is 30-45 s, and the diameter of the fiber bundle is 20-50 μm.

[0011] Preferably, in S4, the fiber bundle is added to deionized water and stirred to form a fiber suspension with a concentration of 0.8%-1.5% at a stirring rate of 300-500 r / min; during screening, the fiber bundle is passed through a 200-400 mesh sieve in a 35-40 kHz ultrasonic environment for 15-25 min.

[0012] Preferably, in S5, the purified fiber bundle is transported to the stretching equipment, the stretching ratio is 2-4 times, the stretching speed is 10-20min, and the stretching area of ​​the stretching equipment is provided with a normal pressure argon plasma nozzle, the nozzle is 10-15mm away from the purified fiber bundle, the processing power is 200-300W, and the argon flow rate is 12-15L / min.

[0013] Preferably, in S6, the freezing temperature is -5°C, the freezing time is 2-3h, the thawing temperature is 40°C, the thawing time is 1-1.5h, the drying treatment is vacuum drying, the drying temperature is 40-50°C, the vacuum degree is -0.08 to -0.06MPa, and the bamboo fiber is dried to a moisture content of 8-12%.

[0014] In the present invention, steam explosion utilizes high-temperature, high-pressure steam to instantly vaporize water within the bamboo cell walls. The mechanical impact force generated by the sudden pressure drop disrupts the bond between lignin, hemicellulose, and cellulose, opening up structural pathways for subsequent processing. In the composite enzymatic hydrolysate, xylanase targets hemicellulose, while laccase and manganese peroxidase synergistically degrade lignin. Under the optimal buffer environment, impurities surrounding the cellulose are directionally stripped away, preserving the main cellulose structure.

[0015] Supercritical CO2, with its high permeability and swelling properties, penetrates the gaps between fibers and softens residual lignin, and cooperates with the shearing force of the twin-screw to achieve gentle separation of fiber bundles and avoid mechanical damage.

[0016] Ultrasonic screening disperses fibers and removes impurities through vibration energy, thereby improving uniformity. Plasma treatment etches the fiber surface with high-energy particles, introducing polar groups and increasing roughness, thereby strengthening interfacial bonding capabilities.

[0017] Freeze-thaw, through the expansion and slow melting of ice crystals, relaxes stress within the fibers and stabilizes the microstructure. These steps work synergistically to ultimately achieve the efficient production of high-performance continuous bamboo fibers.

[0018] Therefore, the present invention adopts the above-mentioned continuous bamboo fiber preparation method, which can not only prepare bamboo fibers with excellent performance, high purity and good uniformity, effectively solving the problems of poor fiber quality and insufficient stability existing in traditional methods, but also improve production efficiency, reduce environmental pollution and energy consumption, and reduce production costs, taking into account high performance, continuity and green economy. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further illustrated by the following examples.

[0020] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0021] In the present invention, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in this field and can be purchased through commercial channels.

[0022] Example 1 The present invention provides a method for preparing continuous bamboo fiber, comprising the following steps: S1. Select 3-year-old bamboo, cut into 1m lengths, remove bamboo nodes and surface impurities, place the bamboo segments in a steam explosion device, introduce 0.5MPa saturated steam, maintain for 80s, then instantly reduce the pressure to room temperature to initially dissociate the bamboo segments.

[0023] S2. Immerse the preliminarily dissociated bamboo in a composite enzymatic hydrolysis solution and stir for enzymatic hydrolysis. The solid-liquid ratio of the composite enzymatic hydrolysis solution to the preliminarily dissociated bamboo is 1:15. The composite enzymatic hydrolysis solution is a citric acid buffer solution with a pH of 4. The mass ratio of xylanase, laccase and manganese peroxidase is 1.5:1:0.5. The enzymatic hydrolysis temperature is 50°C, the time is 2h, the stirring rate is 100r / min, and the bamboo is rinsed with deionized water three times after enzymatic hydrolysis.

[0024] S3. Send the bamboo material rinsed in S2 to the separator, rotate the twin-screw separator with a length-to-diameter ratio of 40:1, a screw speed of 150 r / min, a feeding zone of 80°C and 0.3 MPa, a main separation zone of 110°C and 15 MPa, a discharge zone of 90°C and 0.5 MPa, and inject supercritical CO2 into the main separation zone at an injection rate of 0.5 kg / kg of bamboo material. Stay for 30 seconds to obtain a fiber bundle with a diameter of 30 μm. S4. Add deionized water to the fiber bundle obtained in S3 and stir to prepare a fiber suspension with a concentration of 0.8% at a stirring rate of 300 r / min. Pass the suspension through a 200-mesh sieve in a 35 kHz ultrasonic environment for 15 min.

[0025] S5. The fiber bundle purified by S4 is transported to the drafting equipment with a drafting multiple of 2 times and a drafting speed of 10 m / min. The distance between the atmospheric pressure argon plasma nozzle and the fiber bundle in the drafting zone is 10 mm, the processing power is 200 W, and the argon flow rate is 12 L / min.

[0026] S6. The fiber bundle after S5 stretching is frozen at -5°C for 2 hours, then thawed at 40°C for 1 hour, and finally dried at 40°C under vacuum, at a vacuum degree of -0.08 MPa, until the moisture content reaches 8%.

[0027] Performance data: breaking strength 400MPa, lignin residue rate 8%, whiteness 70%, bonding strength with epoxy resin 8.5MPa.

[0028] Example 2 The difference from Example 1 is that the mass ratio of xylanase, laccase and manganese peroxidase in S2 is 2:1:0.8, and the other conditions are the same.

[0029] The breaking strength is 415MPa, the lignin residual rate is 7.2%, the whiteness is 71.5%, and the bonding strength with epoxy resin is 8.9MPa.

[0030] Example 3 The difference between Example 1 and Comparative Example 3 is that the supercritical CO2 injection amount in S3 is 0.6 kg / kg bamboo, and the rest of the conditions are the same.

[0031] Performance data: breaking strength 406 MPa, lignin residual rate 7.7%, brightness 70.6%, and epoxy resin bonding strength 8.6 MPa.

[0032] Comparative Example 1 The difference between Example 1 and Comparative Example 3 is that the supercritical CO2 injection amount in S3 is 0.6 kg / kg bamboo, and the rest of the conditions are the same.

[0033] Performance data: breaking strength 280 MPa, lignin residual rate 15%, brightness 60%, and epoxy resin bonding strength 5 MPa.

[0034] Comparative Example 2 The difference between Example 1 and Comparative Example 3 is that the supercritical CO2 injection amount in S3 is 0.6 kg / kg bamboo, and the rest of the conditions are the same.

[0035] Performance data: breaking strength 345 MPa, lignin residual rate 12.5%, brightness 66.5%, and epoxy resin bonding strength 6.8 MPa.

[0036] Comparative Example 3 The difference between Example 1 and Comparative Example 3 is that the supercritical CO2 injection amount in S3 is 0.6 kg / kg bamboo, and the rest of the conditions are the same.

[0037] Performance data: breaking strength 320 MPa, lignin residual rate 10%, brightness 65%, and epoxy resin bonding strength 6 MPa.

[0038] Comparative Example 4 The difference between Example 1 and Comparative Example 3 is that the supercritical CO2 injection amount in S3 is 0.6 kg / kg bamboo, and the rest of the conditions are the same.

[0039] Performance data: breaking strength 385 MPa, lignin residual rate 8%, brightness 69.5%, and epoxy resin bonding strength 8.1 MPa.

[0040] Comparing Example 1 and Example 2, it can be seen that by adjusting the mass ratio of xylanase, laccase and manganese peroxidase in the composite enzyme from 1.5:1:0.5 to 2:1:0.8 in Example 2, the performance is significantly improved, the breaking strength is increased from 400 MPa to 415 MPa, the lignin residual rate is reduced from 8% to 7.2%, and the brightness and bonding strength are also optimized. The reason is that xylanase mainly decomposes hemicellulose, and laccase and manganese peroxidase cooperatively degrade lignin. Appropriately increasing the proportion of xylanase (from 1.5 to 2) can more fully destroy the hemicellulose connection between bamboo fibers, creating a more sufficient contact interface for laccase and manganese peroxidase (proportion from 0.5 to 0.8) to degrade lignin, thereby reducing lignin residues and improving fiber purity and mechanical properties.

[0041] From Comparative Example 1 and Example 3, it can be seen that the injection amount of supercritical CO2 is increased from 0.5 kg / kg bamboo to 0.6 kg / kg in Example 3, and the breaking strength is increased from 400 MPa to 406 MPa, and the lignin residual rate is decreased from 8% to 7.7%. The reason is that supercritical CO2 is in a supercritical state at 110°C and 15 MPa, can swell lignin and reduce the friction between fibers. After the injection amount is increased, the swelling and extraction of lignin are enhanced, the fiber separation is more complete, and the lignin residue is slightly reduced; but the improvement is small, indicating that 0.5 kg / kg is close to the optimal injection amount, and excessive injection has limited performance improvement (limited by the saturation of fiber bundle and CO2 contact).

[0042] From Comparative Example 1 and Comparative Example 1, it can be seen that the pressure in the main separation zone is reduced to 0.8 MPa in Comparative Example 1, which is much lower than the critical pressure of CO2 of 7.38 MPa, and no supercritical CO2 is injected, resulting in a sharp decrease in performance, with the breaking strength decreasing from 400 MPa to 280 MPa, the lignin residual rate increasing from 8% to 15%, and the whiteness decreasing from 70% to 60%. The reason is that CO2 is in a gaseous state at 0.8 MPa, which cannot achieve the swelling and lubrication functions of the supercritical state, the fiber bundle is easily broken by excessive mechanical shear force during the separation process, and the lignin cannot be effectively removed. The residual lignin causes uneven fiber structure, resulting in a significant decrease in mechanical properties and whiteness. This comparison directly verifies the key role of supercritical CO2 in maintaining fiber integrity and reducing lignin residue.

[0043] From Comparative Example 1 and Comparative Example 2, it can be seen that the pH of the complex enzyme solution is increased from 4 to 6 in Comparative Example 2, the breaking strength is decreased from 400 MPa to 345 MPa, and the lignin residual rate is increased from 8% to 12.5%. The reason is that the optimum pH of xylanase and laccase is 4-5, and the enzyme activity is significantly reduced when the pH is increased to 6, the spatial structure of the enzyme is destroyed, and the degradation of hemicellulose and lignin is not sufficient, resulting in more impurities remaining in the fiber and a decrease in mechanical properties.

[0044] From Comparative Example 1 and Comparative Example 3, it can be seen that the rinsing process after enzymatic hydrolysis is omitted in Comparative Example 3, the breaking strength is decreased from 400 MPa to 320 MPa, and the whiteness is decreased from 70% to 65%. The reason is that the enzyme preparation (protein) and degradation products (such as xylose and phenols) remaining after enzymatic hydrolysis are not removed, and will carbonize to form coking substances during subsequent high-temperature (S3 main separation zone 110°C) treatment, which will adhere to the fiber surface, not only destroying the continuity of the fiber structure and reducing the strength, but also affecting the whiteness; at the same time, the residual substances will weaken the interfacial bonding force between the fiber and the epoxy resin, from 8.5 MPa to 6 MPa.

[0045] From comparative example 1 and comparative example 4, it can be seen that the breaking strength of comparative example 4 is slightly reduced from 400 MPa to 385 MPa, and the whiteness and bonding strength are slightly decreased when the thawing temperature is reduced from 40 DEG C to 30 DEG C. The reason is that when thawing at 40 DEG C, the ice crystals in the fiber can slowly melt and uniformly seep out, avoiding the damage to the fiber structure caused by the rapid migration of water; while the thawing speed is slower at 30 DEG C, and the ice crystals in some areas remain for too long, which may cause micro-cracks in the fiber, resulting in a small decrease in strength, but the influence is lower than other parameters, because freezing-thawing mainly affects the internal water distribution of the fiber, and has no significant effect on the lignin residue.

[0046] Therefore, the application adopts the above-mentioned continuous bamboo fiber preparation method, which can not only prepare bamboo fibers with excellent performance, high purity and good uniformity, effectively solve the problems of poor fiber quality and insufficient stability existing in traditional methods, but also improve the production efficiency, reduce environmental pollution and energy consumption, and reduce the production cost, and give consideration to high performance, continuity and green economy.

[0047] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing continuous bamboo fiber, characterized by: The following steps are involved: S1, steam explosion of bamboo; S2, enzymatically hydrolyzing the exploded bamboo; S3, sending the enzymatically hydrolyzed bamboo material to a separator for continuous separation to obtain fiber bundles; S4, preparing the fiber bundle into a fiber suspension and screening it to obtain a purified fiber bundle; S5, drafting the purified fiber bundle; S6. Freezing the drawn fiber bundle and then thawing it, and then drying it to obtain continuous bamboo fibers.

2. The method for preparing continuous bamboo fiber according to claim 1, wherein: The specific operation of S1 is as follows: select 3-4 year old bamboo, cut the bamboo into 1-1.5m lengths, remove bamboo nodes and surface impurities, place the obtained bamboo segments in a steam explosion device, pass saturated steam, and then instantly reduce the pressure to room temperature to initially dissociate the bamboo segments.

3. The method for preparing continuous bamboo fiber according to claim 2, wherein: In S1, the bamboo material is one of Phyllostachys pubescens, Phyllostachys moso, and Phyllostachys cirrhosa. The pressure of saturated steam is 0.5-1 MPa, and the saturated steam is introduced for 80-100 seconds.

4. The method for preparing continuous bamboo fiber according to claim 1, wherein: The specific operation of S2 is: first preparing a composite enzymatic hydrolysis solution, then immersing the preliminarily dissociated bamboo into the composite enzymatic hydrolysis solution and stirring for enzymatic hydrolysis, after the enzymatic hydrolysis is completed, filtering to separate the enzymatically hydrolyzed bamboo and the enzymatic hydrolysis solution, and rinsing the separated enzymatically hydrolyzed bamboo with deionized water.

5. The method for preparing continuous bamboo fiber according to claim 4, wherein: In S2, the solid-liquid ratio of the composite enzymatic hydrolysis solution to the preliminarily dissociated bamboo is 1:(15-20), the composite enzymatic hydrolysis solution is a citric acid buffer with a pH of 4-5, the citric acid buffer contains xylanase, laccase and manganese peroxidase, the mass ratio of xylanase, laccase and manganese peroxidase is (1.5-2):1:(0.5-0.8), the enzymatic hydrolysis temperature is 50-60°C, the enzymatic hydrolysis time is 2-3h, the stirring rate is 100-150r / min, and the number of rinsing times is 3-5 times.

6. The method for preparing continuous bamboo fiber according to claim 1, wherein: In S3, the separator is a rotary twin-screw separator with a length-to-diameter ratio of 40:1 and a screw speed of 150-250 r / min. The separator adopts three-stage temperature control and stepped pressure control. The feed zone is 80°C and 0.3 MPa, the main separation zone is 110°C and 15-20 MPa, and the discharge zone is 90°C and 0.5 MPa. Supercritical CO2 is injected into the main separation zone of the separator. The injection amount of supercritical CO2 is 0.5-0.8 kg / kg of bamboo. After the supercritical CO2 is injected, it stays for 30-45 seconds. The diameter of the fiber bundle is 20-50 μm.

7. The method for preparing continuous bamboo fiber according to claim 1, wherein: In S4, the fiber bundle is added to deionized water and stirred to form a fiber suspension with a concentration of 0.8%-1.5% at a stirring rate of 300-500 r / min; during screening, the fiber bundle is passed through a 200-400 mesh sieve in a 35-40 kHz ultrasonic environment for 15-25 minutes.

8. The method for preparing continuous bamboo fiber according to claim 1, wherein: In S5, the purified fiber bundle is transported to the drawing equipment with a drawing ratio of 2-4 times and a drawing speed of 10-20min. The drawing area of ​​the drawing equipment is provided with a normal pressure argon plasma nozzle, the nozzle is 10-15mm away from the purified fiber bundle, the processing power is 200-300W, and the argon flow rate is 12-15L / min.

9. The method for preparing continuous bamboo fiber according to claim 1, wherein: In S6, the freezing temperature is -5°C, the freezing time is 2-3h, the thawing temperature is 40°C, the thawing time is 1-1.5h, the drying treatment is vacuum drying, the drying temperature is 40-50°C, the vacuum degree is -0.08 to -0.06MPa, and the bamboo fiber is dried to a moisture content of 8-12%.