A method for preparing raw bamboo fiber based on a formic acid / sodium sulfite composite system

Abstract

This invention discloses a method for preparing raw bamboo fiber based on a performic acid / sodium sulfite composite system. The raw bamboo is treated with a performic acid and sodium sulfite composite system, achieving a lignin removal rate of 97-100% while minimizing damage to the bamboo fiber. The fiber strength after this treatment is significantly increased, making it suitable for textiles and other fields. The product of this invention combines the high-quality qualities of crude bamboo obtained through alkali treatment and redox principles, yielding spinnable raw bamboo monofilaments with a diameter of several hundred micrometers, high degree of delignification, good whiteness, and excellent strength.

Description

Technical Field

[0001] This invention belongs to the field of textiles, specifically relating to a method for preparing high-quality bamboo fiber based on a performic acid / sodium sulfite composite system. Background Technology

[0002] Traditional methods for preparing bamboo fiber include mechanical splitting and dissolution regeneration, with dissolution regeneration currently being the primary method for producing spinnable fibers. The traditional dissolution regeneration process requires complex steps such as dissolution and spinning, consuming large amounts of organic solvents, which is not environmentally friendly and results in high costs. Furthermore, the process damages the original functional structure of the bamboo fibers (such as antibacterial and UV-resistant properties). On the other hand, the bamboo fibers obtained through mechanical splitting have insufficient fineness, poor uniformity, and are brittle, making them unsuitable for textile applications. Summary of the Invention

[0003] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing high-quality raw bamboo fiber by combining oxidation-reduction and alkali delignination, which addresses the shortcomings of the existing technology.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing raw bamboo fiber based on a formic acid / sodium sulfite composite system includes the following steps:

[0006] (1) Mix the peroxyformic acid solution with the raw bamboo after the fiber splitting treatment and heat it;

[0007] (2) The crude fiber obtained in step (1) is washed and then mixed with a sodium sulfite solution and heated.

[0008] (3) Let the mixture obtained in step (2) stand at room temperature to soak;

[0009] (4) The product obtained in step (3) is washed with deionized water and then dried to obtain the final product.

[0010] This invention first involves using peroxyformic acid as an oxidizing agent to induce an electrophilic substitution reaction, primarily disrupting the side chains of lignin and oxidizing the aromatic rings to form dicarboxylic acid derivatives. Then, under alkaline conditions, sodium sulfite reacts with the phenolic structure of the lignin, dissolving the lignin and resulting in a fuller, smoother fiber structure. This causes the cellulose on the fiber strands to swell and separate, yielding regularly shaped, brown fibers. Simultaneously, further delignification and drying are performed to obtain raw bamboo fiber monofilaments with excellent splitting properties and good whiteness.

[0011] Specifically, in step (1), the peroxyformic acid solution is prepared by mixing hydrogen peroxide with a volume concentration of 20-50% and formic acid with a volume concentration of 95-99% in a volume ratio of 2-3:1, and then adding 1-2 wt% sulfuric acid as a catalyst to the mixture.

[0012] Specifically, in step (1), the ratio of raw bamboo after filament separation to peroxyformic acid solution is 10g:(300~500)ml.

[0013] Specifically, in step (1), the peroxyformic acid solution is mixed with the raw bamboo after the fiber splitting treatment, and then heated to 50-55℃ for 5-6 hours.

[0014] Specifically, in step (2), the coarse fibers are washed with deionized water, and the washing is done as gently as possible.

[0015] Specifically, in step (2), the sodium sulfite system solution is prepared by mixing 10-20g of sodium hydroxide, 6-9g of sodium sulfite, and 0.15-0.35g of sodium silicate with 300-500ml of water. The function of sodium silicate is to enhance flexibility and abrasion resistance.

[0016] Specifically, in step (2), the ratio of the amount of washed crude fiber to sodium sulfite solution is 10g:(300~500)ml.

[0017] Specifically, in step (2), the system is heated from room temperature to a temperature of 101-106°C and reacted for 4-7 hours.

[0018] Specifically, in step (3), the mixture is left to stand and soak at room temperature for 36 to 60 hours.

[0019] Specifically, in step (4), the drying temperature is 45-60℃ and the time is 6-12h.

[0020] Beneficial effects:

[0021] (1) Compared with the prior art, the product of the present invention has the superior quality of crude product obtained by alkali treatment principle and oxidation-reduction principle, with a single filament diameter of hundreds of micrometers, high degree of delignification, good whiteness and excellent strength, and spinnable raw bamboo single filament.

[0022] (2) This invention does not require dissolving the original properties of bamboo and has lower energy consumption. The finished bamboo fiber has initially demonstrated good fabric properties and retains the original bamboo fiber characteristics, showing potential in green sustainable development and fabric antibacterial properties. Attached Figure Description

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0024] Figure 1 This is a flowchart of the present invention.

[0025] Figure 2 This is a scanning electron microscope image of the raw bamboo fiber after treatment in Example 1.

[0026] Figure 3 This is a microscopic image of the raw bamboo fiber after treatment in Example 1.

[0027] Figure 4 These are scanning electron microscope (SEM) images of the products from each step of the processing in Example 1.

[0028] Figure 5 This is a macroscopic comparison of the products produced by the method of this invention and two traditional methods.

[0029] Figure 6 This is an X-ray diffraction pattern of bamboo fiber obtained by the present invention.

[0030] Figure 7 These are infrared spectra of the fibers and natural bamboo fibers after the present invention.

[0031] Figure 8 This is a comparison chart of fiber strength after treatment in Example 1, Comparative Example 1, and Comparative Example 2.

[0032] Figure 9 This is an image showing the effect of treating bamboo fibers with a lower concentration of formic acid solution in Example 4.

[0033] Figure 10 This is an image showing the effect of bamboo fibers after processing in Example 5. Detailed Implementation

[0034] The present invention can be better understood from the following embodiments.

[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0036] Example 1: Preparation of Fibers

[0037] according to Figure 1 The process shown is used to prepare fibers:

[0038] (1) Separation of bamboo fibers: Five-year-old bamboo is selected and separated into fine bamboo fibers of 0.35*0.14mm by mechanical separation.

[0039] (2) Peroxyformic acid treatment: Prepare a peroxyformic acid solution using 289ml of 30% hydrogen peroxide solution, 112ml of 98% formic acid solution and 2.6ml of concentrated sulfuric acid. After standing for two hours, add 10g of bamboo fiber and gently heat to 50℃ for 5 hours.

[0040] (3) Take out the processed bamboo strips, rinse them with clean water, and then soak them in deionized water for 20 minutes.

[0041] (4) Sodium sulfite system treatment: Weigh 7.56g sodium sulfite, 15.0g sodium hydroxide and 0.2g sodium silicate to prepare a 400ml solution and heat it at 104℃ for 4h.

[0042] (5) Take out the treated bamboo strips and soak them in deionized water 3 to 5 times. At the same time, prepare a sodium sulfite system solution and soak the cleaned bamboo strips in the sodium silicate solution for 48 hours.

[0043] (6) Clean the bamboo strips and dry them at 50℃ for 8 hours to obtain the product.

[0044] Figure 4 Scanning electron microscope (SEM) images of the products from each step of the processing. Figure 4 Cross-sectional observation of the lignin-derived matrix reveals that after delignification, the vessels in the lignin portion disappear, the fiber structure becomes circular, and the central pores disappear due to the denser recrystallization of cellulose. Figure 4 As can be seen from the side, the delignified fibers exhibit a distinct linear structure, with lignin and gums between the fibers removed, resulting in a smooth fiber surface, which explains the glossy appearance of the fibers after delignification. This invention demonstrates a significant effect in removing lignin between fibers.

[0045] Comparative Example 1: The raw bamboo fibers were treated with the formic acid solution prepared in Example 1 for 12 hours, washed, and dried at 50°C for 8 hours to obtain fibers.

[0046] Comparative Example 2: The raw bamboo fibers were treated with the sodium sulfite solution prepared in Example 1 for 7 hours, washed, and then dried at 50°C for 8 hours to obtain fibers.

[0047] Example 2: Microscopic Comparison: Electron Microscopy, Spectrometer Detection, X-ray Diffraction

[0048] (1) Electron microscopy examination of the finished fibers from Example 1: The morphology was observed using a scanning electron microscope. Figure 2 This is a scanning electron microscope image of the raw bamboo fiber after treatment in Example 1. Figure 3These are model images of raw bamboo fibers before and after treatment in Example 1. It can be seen that after treatment, the fiber light transmittance is higher, the longitudinal linear structure is more obvious, the delignification effect is significant, and more hydrogen bonds are exposed in the bamboo fibers. The microscopic morphology of the raw bamboo fibers is blurred, the fiber linear structure is not obvious, and the longitudinal linear structure and parenchymal cells are barely visible. After treatment, it is clearly evident that lignin and cellulose are destroyed and more hydrogen bonds are exposed.

[0049] (2) The finished product of Example 1 was analyzed by X-ray diffraction (MiniFlex 600 Hangzhou Leimai Technology Co., Ltd.).

[0050] Depend on Figure 6 It can be seen that the crystallization peaks of the samples after delignification treatment are all located near 2θ = 15.8° and 22.5°, corresponding to the (110) and (200) crystal planes, respectively, indicating that the delignification process did not change the crystal lattice structure of the original fiber. The crystallinity of the bamboo fiber obtained after delignification is significantly increased.

[0051] (3) FTIR infrared spectroscopy detection of the finished product of Example 1: The fiber was scanned by an infrared spectrometer (Fourier transform infrared spectrometer IS20 Thermo Fisher Scientific).

[0052] Depend on Figure 7 It can be seen that the fibers treated by this invention did not show any new absorption peaks compared to natural bamboo fibers, indicating that no chemical change occurred in the cellulose during the reaction. The consistent positions of the absorption peaks in the hydrogen bond region verify the conclusion that no chemical change occurred in the cellulose.

[0053] Example 3 Macroscopic Comparison: Strength Detection and Filamentation Comparison

[0054] (1) Figure 5 A macroscopic comparison of the products of Embodiment 1 and Comparative Examples 1 and 2 of the present invention clearly shows that the bamboo fibers obtained by the present invention are whiter and have better fiber separation.

[0055] (2) Strength test of single fiber of the finished product in Example 1: The fiber strength was tested using an electronic strength tester (electronic single fiber strength tester YG004 Changzhou Tianrong Instrument Equipment Co., Ltd.).

[0056] Figure 8 The bar chart shows a comparison of the average fiber strength of Comparative Examples 1 and 2 with that of the present invention. The bar chart clearly shows that the bamboo fibers produced by this invention have significantly higher strength than those of Comparative Examples 1 and 2.

[0057] Example 4: Treatment of bamboo fibers with a low concentration of formic acid solution

[0058] Replace the 10 v / v% peroxyformic acid solution in step (2) of Example 1 with a 5 v / v% peroxyformic acid solution. The treated bamboo fibers are as follows: Figure 9 As shown. Figure 9 -a is the crude fiber after treatment with formic acid for 5 hours; 9-b is the crude fiber after treatment with sodium sulfite for 4 hours and soaking for 48 hours; 9-c is the final product obtained after drying at 50℃ for 8 hours. 9-d is the final sample of Example 1. It can be clearly seen that the color and fiber separation are poor.

[0059] Example 5: Bamboo fibers treated with sodium sulfite system without the addition of sodium silicate.

[0060] In Example 1, sodium silicate was not added to the sodium sulfite system in steps (4) and (5), and the soaking step was performed before the sodium sulfite treatment. The treatment results are as follows: Figure 10 As shown in the figure. 10-a is the crude fiber treated with heating for 4 hours after soaking in the sodium sulfite system; 10-b is the crude fiber after filtration and washing; 10-c is the finished product after drying at 50℃ for 6 hours. 10-d is the final sample of Example 1. The comparison shows that the finished product obtained without the addition of sodium silicate has good color, but cannot form complete fibers.

[0061] This invention provides a concept and method for preparing raw bamboo fiber based on a formic acid / sodium sulfite composite system. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing raw bamboo fiber based on a formic acid / sodium sulfite composite system, characterized in that, Includes the following steps: (1) Mix the peroxyformic acid solution with the raw bamboo after the fiber splitting treatment and heat it; (2) Wash the crude fiber obtained in step (1) and mix it with the sodium sulfite solution and heat it; (3) Let the mixture obtained in step (2) stand at room temperature to soak; (4) Wash the product obtained in step (3) with deionized water and then dry it to obtain the final product; In step (1), the peroxyformic acid solution is prepared by mixing hydrogen peroxide with a volume concentration of 20-50% and formic acid with a volume concentration of 95-99% in a volume ratio of 2-3:1, and then adding 1-2 wt% sulfuric acid as a catalyst to the mixture; the ratio of raw bamboo after fiber separation to peroxyformic acid solution is 10g:(300-500)ml; after mixing the peroxyformic acid solution with the raw bamboo after fiber separation, the mixture is heated to 50-55℃ and reacted for 5-6 hours. The sodium sulfite system solution is prepared by mixing 10-20g of sodium hydroxide, 6-9g of sodium sulfite, and 0.15-0.35g of sodium silicate with 300-500ml of water; the ratio of the washed coarse fiber to the sodium sulfite system solution is 10g:(300-500)ml; In step (2), the temperature is heated from room temperature to 101~106℃ and the reaction is carried out for 4~6 hours.

2. The method for preparing raw bamboo fiber based on the performic acid / sodium sulfite composite system according to claim 1, characterized in that, In step (2), the coarse fibers are washed with deionized water.

3. The method for preparing raw bamboo fiber based on the permethrin / sodium sulfite composite system according to claim 1, characterized in that, In step (3), the mixture is left to stand and soak at room temperature for 36 to 60 hours.

4. The method for preparing raw bamboo fiber based on the performic acid / sodium sulfite composite system according to claim 1, characterized in that, In step (4), the drying temperature is 45~60℃ and the time is 6~12h.

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