A continuous bamboo fiber production method

Abstract

The application discloses a continuous bamboo fiber preparation method, and belongs to the technical field of bamboo fiber preparation, and comprises the following steps: steam blasting bamboo; carrying out enzymolysis on the blasted bamboo; continuously separating the bamboo after the enzymolysis in a separator to obtain fiber bundles; preparing the fiber bundles into fiber suspension and screening to obtain purified fiber bundles; drawing the purified fiber bundles; carrying out freezing treatment on the drawn fiber bundles, then carrying out thawing treatment, and finally carrying out drying treatment to obtain continuous bamboo fibers. The continuous bamboo fiber preparation method can not only prepare bamboo fibers with excellent performance, high purity and good uniformity, effectively solves the problems of poor fiber quality and insufficient stability in traditional methods, but also improves production efficiency, reduces environmental pollution and energy consumption, and reduces production cost, and is high in performance, continuity and green economy.

Description

Technical Field

[0001] This invention relates to the field of bamboo fiber preparation technology, and in particular to a continuous bamboo fiber preparation method. Background Technology

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

[0003] Traditional methods for preparing bamboo fiber mainly include chemical and mechanical methods. Chemical methods treat bamboo with strong alkalis and acids, effectively removing impurities such as lignin and hemicellulose. However, these methods suffer from severe environmental pollution, significant fiber damage, and difficulties in recovering chemical reagents. Furthermore, the wastewater generated during production is costly to treat, which contradicts the principles of green manufacturing. Mechanical methods primarily use physical crushing and grinding to dissociate bamboo fibers. While this reduces chemical pollution, the resulting fiber bundles are larger in diameter and uneven in length, with high lignin residue and poor fiber performance, failing to meet the demands of high-end applications for refined and high-performance fibers. Summary of the Invention

[0004] The purpose of this invention is to provide a continuous bamboo fiber preparation method. Through the synergistic optimization and continuous design of each process step, it can produce bamboo fibers with excellent performance, high purity and good uniformity, effectively solving the problems of poor fiber quality and insufficient stability in traditional methods. It can also improve production efficiency, reduce environmental pollution and energy consumption, and lower production costs, thus taking into account high performance, continuity and green economy.

[0005] To achieve the above objectives, the present invention provides a method for preparing continuous bamboo fiber, comprising the following steps:

[0006] S1, Steam-exploded bamboo;

[0007] S2. Enzymatically hydrolyze the blasted bamboo;

[0008] S3. The enzymatically hydrolyzed bamboo is sent to a separator for continuous separation to obtain fiber bundles;

[0009] S4. The fiber bundle is made into a fiber suspension and screened to obtain the purified fiber bundle.

[0010] S5. Stretch the purified fiber bundles;

[0011] S6. The stretched fiber bundles are frozen and then thawed, and then dried to obtain continuous bamboo fiber.

[0012] Preferably, the specific operation of S1 is as follows: select 3-4 year old bamboo, cut the bamboo into lengths of 1-1.5m, remove bamboo nodes and surface impurities, place the obtained bamboo segments in a steam explosion device, introduce saturated steam, and then instantly reduce the pressure to room temperature to initially separate the bamboo segments.

[0013] Preferably, in S1, the bamboo material is one of moso bamboo, dwarf bamboo, or nephrolepis cordifolia, the pressure of the saturated steam is 0.5-1 MPa, and the saturated steam is introduced and maintained for 80-100 seconds.

[0014] Preferably, the specific operation of S2 is as follows: first, prepare a compound enzymatic hydrolysate, then immerse the initially dissociated bamboo in the compound enzymatic hydrolysate and stir to hydrolyze it, after the enzymatic hydrolysis is completed, filter to separate the enzymatically hydrolyzed bamboo and the enzymatic hydrolysate, and rinse the separated enzymatically hydrolyzed bamboo with deionized water.

[0015] Preferably, in S2, the solid-liquid ratio of the compound enzymatic hydrolysate to the initially dissociated bamboo is 1:(15-20), the compound enzymatic hydrolysate is citrate buffer with a pH of 4-5, the citrate 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℃, the enzymatic hydrolysis time is 2-3h, the stirring rate is 100-150r / min, and the number of rinsing times is 3-5.

[0016] Preferably, 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 regulation. The feeding zone is 80℃ and 0.3MPa, the main separation zone is 110℃ and 15-20MPa, and the discharge zone is 90℃ and 0.5MPa. Supercritical CO2 is injected into the main separation zone of the separator. The amount of supercritical CO2 injected is 0.5-0.8 kg / kg of bamboo. After the supercritical CO2 is injected, the bamboo remains for 30-45 seconds, and the diameter of the fiber bundle is 20-50 μm.

[0017] Preferably, in step S4, the fiber bundle is added to deionized water and stirred to prepare 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 an ultrasonic environment of 35-40 kHz for a duration of 15-25 min.

[0018] Preferably, in step S5, the purified fiber bundle is conveyed to the drawing equipment, the drawing ratio is 2-4 times, the drawing speed is 10-20 min, the drawing zone of the drawing equipment is equipped with an atmospheric pressure argon plasma nozzle, the nozzle is 10-15 mm away from the purified fiber bundle, the processing power is 200-300 W, and the argon flow rate is 12-15 L / min.

[0019] Preferably, in S6, the freezing temperature is -5℃, the freezing time is 2-3h, the thawing temperature is 40℃, the thawing time is 1-1.5h, the drying treatment is vacuum drying, the drying temperature is 40-50℃, the vacuum degree is -0.08 to -0.06MPa, and the bamboo fiber moisture content is 8-12%.

[0020] In this invention, steam explosion utilizes high-temperature and high-pressure steam to instantly vaporize the water inside the bamboo cell walls. The mechanical impact force generated by the sudden pressure drop breaks the bond between lignin, hemicellulose, and cellulose, opening structural channels for subsequent processing. In the compound enzymatic hydrolysate, xylanase targets and decomposes hemicellulose, while laccase and manganese peroxidase synergistically degrade lignin. Under the optimal environment maintained by the buffer solution, impurities around cellulose are directionally removed, preserving the main structure of cellulose.

[0021] Supercritical CO2, with its high permeability and swelling properties, penetrates the interfiber spaces and softens residual lignin. Combined with the shearing force of a twin-screw extruder, it achieves gentle separation of fiber bundles, avoiding mechanical damage.

[0022] Ultrasonic screening disperses fibers and removes coarse impurities through vibration energy, improving uniformity; plasma treatment uses high-energy particles to etch the fiber surface, introduces polar groups and increases roughness, strengthening interfacial bonding ability.

[0023] Freezing and thawing relax the internal stress of the fibers and stabilize the microstructure through the expansion and slow melting of ice crystals. The synergistic effect of these steps ultimately achieves the efficient preparation of high-performance continuous bamboo fibers.

[0024] Therefore, the present invention adopts the above-mentioned continuous bamboo fiber preparation method, which can produce bamboo fibers with excellent performance, high purity and good uniformity, effectively solving the problems of poor fiber quality and insufficient stability in traditional methods, while improving production efficiency, reducing environmental pollution and energy consumption, and lowering production costs, thus taking into account high performance, continuity and green economy. Detailed Implementation

[0025] The technical solution of the present invention will be further described below through embodiments.

[0026] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0027] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0028] Example 1

[0029] This invention provides a method for preparing continuous bamboo fiber, comprising the following steps:

[0030] S1. Select 3-year-old moso bamboo, cut it 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 and then instantly reduce the pressure to room temperature, and the bamboo segments are initially separated.

[0031] S2. Immerse the partially dissociated bamboo in a compound enzymatic hydrolysate and stir to hydrolyze. The solid-liquid ratio of the compound enzymatic hydrolysate to the partially dissociated bamboo is 1:15. The compound enzymatic hydrolysate is a citrate buffer solution with pH=4. The mass ratio of xylanase, laccase and manganese peroxidase is 1.5:1:0.5. The enzymatic hydrolysis temperature is 50℃, the time is 2h, and the stirring rate is 100r / min. After enzymatic hydrolysis, rinse 3 times with deionized water.

[0032] S3. The bamboo material rinsed in S2 is sent to the separator. The rotating twin-screw separator has a length-to-diameter ratio of 40:1, a screw speed of 150 r / min, a feed zone temperature of 80℃ and a pressure of 0.3 MPa, a main separation zone temperature of 110℃ and a pressure of 15 MPa, and a discharge zone temperature of 90℃ and a pressure of 0.5 MPa. Supercritical CO2 is injected into the main separation zone at a rate of 0.5 kg / kg of bamboo material. The mixture is held for 30 s to obtain fiber bundles with a diameter of 30 μm.

[0033] S4. Add the fiber bundle obtained in S3 to deionized water and stir to prepare a fiber suspension with a concentration of 0.8%. Stir at a stirring rate of 300 r / min and pass it through a 200-mesh sieve in a 35 kHz ultrasonic environment for 15 min.

[0034] S5. The fiber bundle purified in S4 is transported to the drawing equipment. The drawing ratio is 2 times, the drawing speed is 10m / min, the atmospheric pressure argon plasma nozzle in the drawing zone is 10mm away from the fiber bundle, the processing power is 200W, and the argon flow rate is 12L / min.

[0035] S6. The fiber bundles stretched in S5 are subjected to freezing treatment at -5℃ for 2 hours, followed by thawing at 40℃ for 1 hour. Finally, they are subjected to drying treatment at a vacuum temperature of 40℃ and a vacuum degree of -0.08MPa until the moisture content is 8%.

[0036] Performance data: tensile strength 400MPa, lignin residue 8%, whiteness 70%, and bond strength with epoxy resin 8.5MPa.

[0037] Example 2

[0038] Unlike Example 1, in S2 the mass ratio of xylanase, laccase and manganese peroxidase was 2:1:0.8, while all other conditions were the same.

[0039] The tensile strength is 415 MPa, the lignin residue rate is 7.2%, the whiteness is 71.5%, and the bond strength with epoxy resin is 8.9 MPa.

[0040] Example 3

[0041] Unlike Example 1, the supercritical CO2 injection rate in S3 was 0.6 kg / kg of bamboo, while all other conditions remained the same.

[0042] Performance data: tensile strength 406MPa, lignin residue 7.7%, whiteness 70.6%, and bond strength with epoxy resin 8.6MPa.

[0043] Comparative Example 1

[0044] Unlike Example 1, the pressure in the main separation zone of S3 is 0.8 MPa, no supercritical CO2 is injected, and all other conditions are the same.

[0045] Performance data: tensile strength 280MPa, lignin residue 15%, whiteness 60%, and bond strength with epoxy resin 5MPa.

[0046] Comparative Example 2

[0047] Unlike Example 1, the pH of the compound enzymatic hydrolysate in S2 was 6, while all other conditions were the same.

[0048] Performance data: tensile strength 345MPa, lignin residue 12.5%, whiteness 66.5%, and bond strength with epoxy resin 6.8MPa.

[0049] Comparative Example 3

[0050] Unlike Example 1, no rinsing step was performed after enzymatic hydrolysis in S2, while all other conditions were the same.

[0051] Performance data: tensile strength 320MPa, lignin residue 10%, whiteness 65%, and bond strength with epoxy resin 6MPa.

[0052] Comparative Example 4

[0053] Unlike Example 1, the thawing temperature in S6 is 30°C.

[0054] Performance data: tensile strength 385MPa, lignin residue 8%, whiteness 69.5%, and bond strength with epoxy resin 8.1MPa.

[0055] Comparing Examples 1 and 2, it can be seen that in Example 2, 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 significantly improved performance. The breaking strength increased from 400 MPa to 415 MPa, the lignin residue rate decreased from 8% to 7.2%, and whiteness and bonding strength were also optimized simultaneously. The reason is that xylanase mainly decomposes hemicellulose, while laccase and manganese peroxidase synergistically degrade lignin. Appropriately increasing the xylanase ratio (from 1.5 to 2) can more fully disrupt the hemicellulose connections between bamboo fibers, creating a more sufficient contact interface for laccase and manganese peroxidase (ratio from 0.5 to 0.8) to degrade lignin, thereby reducing lignin residue and improving fiber purity and mechanical properties.

[0056] Comparing Examples 1 and 3, it can be seen that in Example 3, increasing the supercritical CO2 injection amount from 0.5 kg / kg bamboo to 0.6 kg / kg resulted in a slight increase in breaking strength from 400 MPa to 406 MPa, while reducing the lignin residue rate from 8% to 7.7%. This is because supercritical CO2 exists in a supercritical state at 110℃ and 15 MPa, which can swell lignin and reduce inter-fiber friction. Increasing the injection amount enhances its swelling and extraction effects on lignin, leading to more thorough fiber separation and a slight reduction in lignin residue; however, 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 the fiber bundle's contact with CO2).

[0057] Comparing Example 1 and Comparative Example 1, it can be seen that in Comparative Example 1, the pressure in the main separation zone was reduced to 0.8 MPa, far below the critical CO2 pressure of 7.38 MPa, and no supercritical CO2 was injected. This resulted in a precipitous drop in performance: the breaking strength decreased from 400 MPa to 280 MPa, the lignin residue rate increased from 8% to 15%, and the whiteness decreased from 70% to 60%. The reason is that at 0.8 MPa, CO2 is in a gaseous state and cannot achieve the swelling and lubrication functions of the supercritical state. The fiber bundles are easily broken due to excessive mechanical shear force during separation, and lignin cannot be effectively removed. The residual lignin leads to uneven fiber structure, resulting in a significant decrease in mechanical properties and whiteness. This comparison directly verifies the core role of supercritical CO2 in maintaining fiber integrity and reducing lignin residue.

[0058] Comparing Example 1 and Comparative Example 2, it can be seen that in Comparative Example 2, increasing the pH of the composite enzymatic hydrolysate from 4 to 6 reduced the tensile strength from 400 MPa to 345 MPa and increased the lignin residue from 8% to 12.5%. The reason is that the optimal pH for xylanase and laccase is 4-5. When the pH is increased to 6, the enzyme activity decreases significantly, the spatial structure of the enzyme is destroyed, and the degradation of hemicellulose and lignin is incomplete, resulting in more impurities remaining in the fiber and a decrease in mechanical properties.

[0059] Comparing Example 1 and Comparative Example 3, it can be seen that in Comparative Example 3, omitting the rinsing step after enzymatic hydrolysis resulted in a decrease in breaking strength from 400 MPa to 320 MPa and whiteness from 70% to 65%. The reason is that the residual enzyme preparation (protein) and degradation products (such as xylose and phenols) after enzymatic hydrolysis were not removed. During the subsequent high-temperature treatment (110°C in the S3 main separation zone), they will carbonize to form coke, which adheres to the fiber surface. This not only destroys the continuity of the fiber structure and reduces strength, but also affects whiteness. At the same time, the residual substances weaken the interfacial bonding force between the fiber and the epoxy resin, decreasing it from 8.5 MPa to 6 MPa.

[0060] Comparing Example 1 and Comparative Example 4, it can be seen that when the thawing temperature of Comparative Example 4 was reduced from 40℃ to 30℃, the tensile strength decreased slightly from 400MPa to 385MPa, and the whiteness and bond strength decreased slightly. The reason is that when thawing at 40℃, the ice crystals inside the fiber can melt slowly and seep out evenly, avoiding damage to the fiber structure caused by rapid moisture migration; while the thawing rate at 30℃ is slower, and the ice crystals remain in some areas for too long, which may cause micro-cracks in the fiber, resulting in a slight decrease in strength. However, the impact is less than that of other parameters, because freezing and thawing mainly affects the distribution of moisture inside the fiber and has no significant effect on lignin residue.

[0061] Therefore, the present invention adopts the above-mentioned continuous bamboo fiber preparation method, which can produce bamboo fibers with excellent performance, high purity and good uniformity, effectively solving the problems of poor fiber quality and insufficient stability in traditional methods, while improving production efficiency, reducing environmental pollution and energy consumption, and lowering production costs, thus taking into account high performance, continuity and green economy.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing continuous bamboo fiber, characterized in that: Includes the following steps: S1, Steam-exploded bamboo; S2. Enzymatically hydrolyze the blasted bamboo; The specific operation of S2 is as follows: First, prepare a compound enzymatic hydrolysate, then immerse the initially dissociated bamboo in the compound enzymatic hydrolysate and stir to hydrolyze it. After the enzymatic hydrolysis is completed, filter to separate the enzymatically hydrolyzed bamboo and the enzymatic hydrolysate, and then rinse the separated enzymatically hydrolyzed bamboo with deionized water. In S2, the solid-liquid ratio of the compound enzymatic hydrolysate to the initially dissociated bamboo is 1:(15-20). The compound enzymatic hydrolysate is a citrate buffer with a pH of 4-5. The citrate 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℃, the enzymatic hydrolysis time is 2-3h, the stirring rate is 100-150r / min, and the number of rinsing times is 3-5. S3. The enzymatically hydrolyzed bamboo is sent to a separator for continuous separation to obtain fiber bundles; 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 regulation. The feeding zone is 80℃ and 0.3MPa, the main separation zone is 110℃ and 15-20MPa, and the discharge zone is 90℃ and 0.5MPa. Supercritical CO2 is injected into the main separation zone of the separator at a rate of 0.5-0.8 kg / kg of bamboo. After the supercritical CO2 is injected, the bamboo remains for 30-45 seconds, and the diameter of the fiber bundle is 20-50 μm. S4. The fiber bundle is made into a fiber suspension and screened to obtain the purified fiber bundle. S5. Stretch the purified fiber bundles; S6. The stretched fiber bundles are frozen and then thawed, and then dried to obtain continuous bamboo fiber. In S6, the freezing temperature is -5℃, the freezing time is 2-3h, the thawing temperature is 40℃, the thawing time is 1-1.5h, the drying treatment is vacuum drying, the drying temperature is 40-50℃, the vacuum degree is -0.08 to -0.06MPa, and the bamboo fiber moisture content is 8-12%.

2. The method for preparing continuous bamboo fiber according to claim 1, characterized in that: 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, introduce saturated steam, and then instantly reduce the pressure to room temperature to initially separate the bamboo segments.

3. The method for preparing continuous bamboo fiber according to claim 2, characterized in that: In S1, the bamboo material is one of the following: moso bamboo, basil, or ci bamboo. The pressure of the saturated steam is 0.5-1 MPa, and the saturated steam is introduced and maintained for 80-100 seconds.

4. The method for preparing continuous bamboo fiber according to claim 1, characterized in that: In step S4, the fiber bundle is added to deionized water and stirred to prepare 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 an ultrasonic environment of 35-40 kHz for 15-25 min.

5. The method for preparing continuous bamboo fiber according to claim 1, characterized in that: 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 10-20 m / min. The drawing zone of the drawing equipment is equipped with an atmospheric pressure argon plasma nozzle, with the nozzle 10-15 mm away from the purified fiber bundle, a processing power of 200-300 W, and an argon flow rate of 12-15 L / min.