A preparation method of bamboo charcoal / regenerated cellulose composite fiber

Abstract

The present invention discloses a preparation method of bamboo charcoal / regenerated cellulose composite fiber, which comprises the following steps: S1, obtaining bamboo charcoal particles; S2, dispersing the bamboo charcoal, adding dopamine, tris(hydroxymethyl)aminomethane and functional nanoparticles to obtain a polydopamine-modified bamboo charcoal dispersion; S3, adding a polysiloxane quaternary ammonium salt to obtain modified bamboo charcoal; S4, mixing the modified bamboo charcoal, cellulose and an organic solvent to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution; S5, through wet spinning, obtaining the modified bamboo charcoal / regenerated cellulose composite fiber. The present invention uses polydopamine to increase the density of surface active groups of bamboo charcoal particles, and at the same time utilizes its modification effect and firm combination with nanoparticles to increase the number of active sites, improve the grafting efficiency of bamboo charcoal and the polysiloxane quaternary ammonium salt, realize the interaction between bamboo charcoal and the matrix and the dispersibility in the matrix, so that the prepared modified bamboo charcoal / regenerated cellulose composite fiber has excellent antibacterial properties and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and particularly relates to a preparation method of bamboo charcoal / regenerated cellulose composite fiber. Background Art

[0002] Bamboo charcoal fiber is a new type of functional fiber developed by combining bamboo charcoal with textile fibers, and has characteristics such as adsorption performance, antibacterial and antifungal properties, far-infrared rays, negative ions, heat storage and warmth retention, moisture absorption and breathability, and environmental friendliness. At present, bamboo charcoal fiber has important application prospects in the fields of clothing, home textiles, medical protective clothing, protective clothing for military and aerospace operators, electromagnetic radiation protection masks for household appliances, air filtration materials, etc.

[0003] Regenerated cellulose fiber refers to a regenerated chemical fiber made from natural polymer cellulose (such as wood pulp, cotton linter, etc.) as raw materials by chemical methods, which is basically the same as the original polymer in chemical composition and has a cellulose structure of type II. However, when the particle size of bamboo charcoal is too large or the addition amount in the cellulose dissolution solution is high, it will cause the aggregation of bamboo charcoal in the slurry and cannot be stably dispersed, thus affecting the spinnability of bamboo charcoal fiber and the uniformity of the distribution of bamboo charcoal in the fiber, and further affecting the mechanical properties and functionality of bamboo charcoal fiber. Therefore, the general addition amount of bamboo charcoal in the market is below 3%, and the low addition amount of bamboo charcoal results in poor functions such as adsorption, antibacterial and antifungal properties of the obtained bamboo charcoal fiber. Therefore, how to solve the uniform and stable dispersion of bamboo charcoal in the polymer matrix and improve the interfacial interaction between the polymer and bamboo charcoal at a high bamboo charcoal addition amount to obtain high-performance and multifunctional bamboo charcoal fiber has become a difficulty and the key point.

[0004] The Chinese invention patent with the publication number of CN110158175B discloses a bamboo charcoal slurry for viscose spinning solution and its preparation method. This method uses a protein-type surfactant and a rosin-based hyperbranched surfactant with a specific structure as dispersants together, and the compounding between the two surfactants plays a synergistic effect, which is beneficial to the stable dispersion of bamboo charcoal powder in the aqueous system. The Chinese invention patent with the publication number of CN100558952C discloses bamboo charcoal viscose fiber and its manufacturing method, the surfactant is dialkyl dimethyl ammonium chloride or polyalkyl trimethyl ammonium chloride, and the dispersant is polysiloxane quaternary ammonium salt, dialkoxy silane quaternary ammonium salt or sodium tripolyphosphate. However, the current method of improving the dispersion stability and particle size distribution of bamboo charcoal slurry by adding surfactants still cannot meet the requirements of continuous spinning of viscose spinning solution, and it is easy to occur aggregation and deposition during the spinning process, bringing problems such as poor spinnability and easy breakage of the spinning process, and uneven distribution and many defects in the viscose fiber.

[0005] Organic functional modification of the bamboo charcoal surface is another effective way to improve the dispersibility of bamboo charcoal in the organic matrix, and it can also endow bamboo charcoal with more excellent properties. Patent CN115318260A provides a co-modification of manganese and cyclodextrin, which can improve the dispersibility of the material and increase the active sites of the material, greatly improving the adsorption and degradation performance. However, the particle size of the bamboo charcoal is too large to meet the particle size requirements of fiber spinning.

[0006] Therefore, it is of great significance to develop an efficient and environmentally friendly modification method to prepare functionalized bamboo charcoal, and to be able to perform high-density modification to enhance the dispersibility and interfacial interaction of bamboo charcoal materials in the regenerated cellulose matrix. Summary of the Invention

[0007] The present invention overcomes the deficiencies of the prior art and provides a preparation method of bamboo charcoal / regenerated cellulose composite fibers.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a preparation method of bamboo charcoal / regenerated cellulose composite fibers, comprising the following steps:

[0009] S1. Crush and sieve the bamboo charcoal, wash it with water and dry it to obtain bamboo charcoal particles;

[0010] S2. Disperse the bamboo charcoal in water, add dopamine and tris(hydroxymethyl)aminomethane, adjust the pH value, and add functional nanoparticles during stirring to obtain a polydopamine-modified bamboo charcoal dispersion;

[0011] S3. In the polydopamine-modified bamboo charcoal dispersion, add polysiloxane quaternary ammonium salt, carry out surface in-situ polymerization, then centrifuge, wash and dry to obtain modified bamboo charcoal;

[0012] S4. Mix the modified bamboo charcoal, cellulose and organic solvent to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution;

[0013] S5. The modified bamboo charcoal regenerated cellulose fiber spinning solution is wet-spun and then dried to obtain modified bamboo charcoal / regenerated cellulose composite fibers.

[0014] In a preferred embodiment of the present invention, in the step of S1, the preparation of the bamboo charcoal includes the following steps:

[0015] S11. Wash the bamboo, and dry it at a temperature of 50-80 °C for 3-6 h;

[0016] S12. The dried bamboo is treated at a temperature of 230-300 °C for 1-2 h in an oxygen-free atmosphere, then heated to 450-600 °C and treated for 2-4 h. After the carbonized bamboo charcoal is gradually cooled from the highest calcination temperature to 50-60 °C, a bamboo charcoal blank is obtained;

[0017] S13. Wash the bamboo charcoal blank until it is neutral, and perform a drying treatment at a temperature of 60-100°C for 1-3 hours to obtain bamboo charcoal with a carbon-nitrogen ratio of 86.25-135.42.

[0018] In a preferred embodiment of the present invention, in the step of S1, the bamboo charcoal pulverization includes mechanical ball milling and air milling, and the grinding time is 2-8 hours; the particle size of the pulverized bamboo charcoal is 1-20 μm.

[0019] In a preferred embodiment of the present invention, in the step of S2, the functional nanoparticles are one of silver nanoparticles or zinc oxide nanoparticles, and the particle size is 24-100 nm; the mass ratio of the bamboo charcoal, the dopamine, the tris(hydroxymethyl)aminomethane, the functional nanoparticles and the water is 1-3:0.25-2.4:0.25-3.5:0.5-1.5:100; the pH value is 7-9; the stirring modification time is 2-6 hours.

[0020] In a preferred embodiment of the present invention, in the step of S3, the polysiloxane quaternary ammonium salt is one of 3-(trimethoxysilyl)propyl hexadecyl dimethyl ammonium chloride, 3-(trimethoxysilyl)propyl octadecyl dimethyl ammonium chloride, 3-(triethoxysilyl)propyl hexadecyl dimethyl ammonium chloride or 3-(triethoxysilyl)propyl octadecyl dimethyl ammonium chloride.

[0021] In a preferred embodiment of the present invention, in the step of S3, the mass ratio of the polysiloxane quaternary ammonium salt to the bamboo charcoal is 15-30:1; the time for surface in-situ polymerization is 4-8 hours.

[0022] In a preferred embodiment of the present invention, in the step of S4, the mass ratio of the modified bamboo charcoal, the cellulose and the organic solvent is 0.1-0.3:3-8:85.

[0023] In a preferred embodiment of the present invention, in the step of S4, the cellulose is one of bamboo pulp, cotton pulp, wood pulp or hemp pulp; the organic solvent is one of sodium sulfonate solution, tetrabutylammonium hydroxide / urea solution, alkali / urea solution, N-methylmorpholine-N-oxide solution or 1-allyl-3-methylimidazolium chloride ionic liquid.

[0024] In a preferred embodiment of the present invention, in the step of S5, before wet spinning, the spinning solution of the modified bamboo charcoal regenerated cellulose fiber is centrifuged to remove air bubbles.

[0025] In a preferred embodiment of the present invention, in the step of S5, the modified bamboo charcoal / regenerated cellulose composite fiber is drawn in 2 steps, and the draw ratio is 0.9-1.4.

[0026] The present invention solves the defects existing in the background art and has the following beneficial effects:

[0027] (1) The present invention provides a preparation method of bamboo charcoal / regenerated cellulose composite fiber. The high-density modification of polydopamine on the surface of bamboo charcoal material in the present invention can significantly improve the density of active groups on the surface of bamboo charcoal particles, which is beneficial to improving the grafting efficiency of polysiloxane quaternary ammonium salt after secondary modification. At the same time, by utilizing its modification effect and the firm combination with nanoparticles, the number of active sites on the surface of bamboo charcoal is increased, further improving the grafting efficiency of bamboo charcoal and polysiloxane quaternary ammonium salt, realizing the interaction between the functional bamboo charcoal filler and the matrix and the dispersibility in the matrix. Therefore, the prepared modified bamboo charcoal / regenerated cellulose composite fiber has excellent antibacterial properties and mechanical properties.

[0028] (2) In the present invention, polysiloxane quaternary ammonium salt modified bamboo charcoal is obtained by in-situ polymerization. The method is simple to operate and environmentally friendly. It not only enhances the hydrophilicity and antibacterial property of bamboo charcoal, but also the long-chain structure of polysiloxane quaternary ammonium salt helps to improve the dispersibility of bamboo charcoal in the regenerated cellulose matrix, and thus has a certain impact on the mechanical properties of the fiber. Because the polysiloxane quaternary ammonium salt molecule contains quaternary ammonium groups, due to the polydopamine layer formed on the surface of bamboo charcoal by dopamine, it has good adhesion and reactivity. Therefore, when the polysiloxane quaternary ammonium salt is grafted onto the surface of bamboo charcoal through chemical bonds, the quaternary ammonium groups therein are firmly fixed on the bamboo charcoal particles and dispersed into the regenerated cellulose fibers along with the bamboo charcoal particles, effectively improving the antibacterial property of the fiber. At the same time, the functional groups in the polysiloxane quaternary ammonium salt molecule can form hydrogen bonds or ionic bonds with groups such as hydroxyl groups on the surface of bamboo charcoal and in the regenerated cellulose fiber, not only enhancing the compatibility between bamboo charcoal and regenerated cellulose, but also improving the interfacial bonding force therebetween, thus better improving the mechanical properties of the fiber.

[0029] (3) In the present invention, the composite fiber is endowed with additional antibacterial and mechanical properties by functional nanoparticles. Due to the positive charge on the surface of the functional nanoparticles and the negative charge on the bacterial cell wall, the difference causes the nanoparticles to strongly adsorb on the surface of bacteria and destroy the integrity of the bacterial cell membrane through electrostatic interaction. At the same time, the active sites on the surface of the nanoparticles can react with biomolecules inside the bacteria to further inhibit or kill the bacteria. Moreover, the functional nanoparticles have a large specific surface area and rich surface chemical properties, enabling the nanoparticles to form a strong interaction with the active sites on the surface of bamboo charcoal, increasing the number of active sites on the surface of bamboo charcoal, providing more grafting positions for polysiloxane quaternary ammonium salt, thus improving the grafting efficiency and further improving the antibacterial and mechanical properties.

[0030] (4) In the present invention, bamboo charcoal with a high carbon-nitrogen ratio has more micropores, a larger specific surface area, and unsaturated bonds, which helps the deposition of polydopamine on the surface of bamboo charcoal to be more uniform, increasing the available space for surface active groups. Moreover, the relatively large number of carbon-based active sites on the surface of bamboo charcoal with a high carbon-nitrogen ratio can serve as catalytic centers for the polymerization reaction of polydopamine, enabling the carbon atoms in bamboo charcoal to form strong chemical bonds with the nitrogen atoms in polydopamine, enhancing the interaction between bamboo charcoal and polydopamine, thereby strengthening the interfacial binding force between bamboo charcoal and polydopamine. Therefore, it helps to improve the grafting effect and further enhance its antibacterial and mechanical properties.

[0031] (5) In the present invention, by providing an alkaline modification environment, functional groups such as amino groups and catechol groups in dopamine molecules are more likely to be deprotonated to form negatively charged ions, which can undergo electrostatic interactions and hydrogen bond interactions, promoting the self-polymerization ability of dopamine, enabling it to be applied to the surface modification of functional nanoparticles, helping to stabilize the charge on the surface of nanoparticles, significantly enhancing its stability and dispersibility in aqueous solutions, preventing aggregation, thereby achieving the synergistic effect of dopamine, functional nanoparticles, and polysiloxane quaternary ammonium salts, effectively improving the antibacterial effect and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for describing the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings;

[0033] Figure 1 It is the surface microscopic morphology diagram of the bamboo charcoal fibers prepared in Example 1(a) and Example 2(b) of the present invention;

[0034] Figure 2 It is the cross-sectional microscopic morphology diagram of the bamboo charcoal fibers prepared in Example 1(a), (b) and Example 2(c), (d) of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0037] It should be noted that the raw materials, equipment, reagents, etc. used in the present invention can all be obtained through market purchase or by means of preparation according to existing technologies.

[0038] A method for preparing bamboo charcoal / regenerated cellulose composite fiber, comprising the following steps:

[0039] S1. Crush and sieve bamboo charcoal, wash it with water and dry it to obtain bamboo charcoal particles;

[0040] S2. Disperse bamboo charcoal in water, add dopamine and tris(hydroxymethyl)aminomethane, adjust the pH value, and add functional nanoparticles during stirring to obtain a polydopamine-modified bamboo charcoal dispersion;

[0041] S3. Add polysiloxane quaternary ammonium salt to the polydopamine-modified bamboo charcoal dispersion, carry out surface in-situ polymerization, then centrifuge, wash and dry to obtain modified bamboo charcoal;

[0042] S4. Mix the modified bamboo charcoal, cellulose and organic solvent to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution;

[0043] S5. The modified bamboo charcoal regenerated cellulose fiber spinning solution is wet-spun and then dried to obtain the modified bamboo charcoal / regenerated cellulose composite fiber.

[0044] All commonly used dispersion methods in the art are applicable to the present invention. In one embodiment of the present invention, the dispersion method is to magnetically stir and mix bamboo charcoal and the solution, and then ultrasonically treat at room temperature for 10 - 60 min.

[0045] In some specific embodiments, in the step of S1, the preparation of bamboo charcoal includes the following steps:

[0046] S11. Wash bamboo, and carry out drying treatment at a temperature of 50 - 80°C for 3 - 6 h;

[0047] S12. Treat the dried bamboo in an oxygen-free atmosphere at a temperature of 230 - 300°C for 1 - 2 h, then raise the temperature to 450 - 600°C and treat for 2 - 4 h. After gradually cooling the carbonized bamboo charcoal from the highest calcination temperature to 50 - 60°C, obtain a bamboo charcoal blank;

[0048] S13. Wash the bamboo charcoal blank to neutrality, and carry out drying treatment at a temperature of 60 - 100°C for 1 - 3 h to obtain bamboo charcoal with a carbon-nitrogen ratio of 86.25 - 135.42.

[0049] It should be noted that in the step of S11, bamboo from Dong'an area in Hunan is used as the raw material.

[0050] In some specific embodiments, in the step of S1, the bamboo charcoal crushing includes mechanical ball milling and jet milling, and the grinding time is 2 - 8 h; the particle size of the crushed bamboo charcoal is 1 - 20 μm.

[0051] In some specific embodiments, in the step of S2, the functional nanoparticles are one of silver nanoparticles or zinc oxide nanoparticles, and the particle size is 24 - 100 nm; the mass ratio of bamboo charcoal, dopamine, tris(hydroxymethyl)aminomethane, functional nanoparticles and water is 1 - 3:0.25 - 2.4:0.25 - 3.5:0.5 - 1.5:100; the pH value is 7 - 9; the stirring modification time is 2 - 6 h.

[0052] In some specific embodiments, in the step of S3, the polysiloxane quaternary ammonium salt is one of 3-(trimethoxysilyl)propyl hexadecyl dimethyl ammonium chloride, 3-(trimethoxysilyl)propyl octadecyl dimethyl ammonium chloride, 3-(triethoxysilyl)propyl hexadecyl dimethyl ammonium chloride or 3-(triethoxysilyl)propyl octadecyl dimethyl ammonium chloride; the mass ratio of the polysiloxane quaternary ammonium salt to bamboo charcoal is 15 - 30:1; the time for surface in-situ polymerization is 4 - 8 h.

[0053] In some specific embodiments, in the step of S4, the mass ratio of the modified bamboo charcoal, cellulose and organic solvent is 0.1 - 0.3:3 - 8:85; the cellulose is one of bamboo pulp, cotton pulp, wood pulp or hemp pulp; the organic solvent is one of sodium sulfonate solution, tetrabutylammonium hydroxide / urea solution, alkali / urea solution, N-methylmorpholine-N-oxide solution or 1-allyl-3-methylimidazolium chloride ionic liquid.

[0054] In some specific embodiments, in the step of S5, before wet spinning, the spinning solution of the modified bamboo charcoal regenerated cellulose fiber is centrifuged to remove air bubbles; the modified bamboo charcoal / regenerated cellulose composite fiber is drawn in 2 steps, and the draw ratio is 0.9 - 1.4.

[0055] Example 1

[0056] A method for preparing a bamboo charcoal / regenerated cellulose composite fiber, comprising the following steps:

[0057] S1. Wash the bamboo, and perform drying treatment at a temperature of 60°C for 4 h;

[0058] S2. Treat the dried bamboo in a nitrogen atmosphere at a temperature of 260°C for 1.5 h, raise the temperature to 520°C, and treat for 2 h to complete carbonization. After the carbonized bamboo charcoal is gradually cooled from a temperature of 520°C to 50°C, a bamboo charcoal blank is obtained.

[0059] S3. Wash the bamboo charcoal blank until it is neutral, and dry it at a temperature of 80 °C for 2 h to obtain bamboo charcoal with a carbon-nitrogen ratio of 92.18.

[0060] S4. Put the bamboo charcoal with a carbon-nitrogen ratio of 92.18 into a high-energy ball mill and ball mill for 5 h. After grinding, sieve it through a sieve with a particle size of 2 μm. Take 10 g of the refined bamboo charcoal powder and mix it with 1000 ml of water, and perform centrifugal washing cycle 2 times at a speed of 4000 r / min. Dry the washed bamboo charcoal in a drying oven to obtain bamboo charcoal particles.

[0061] S5. Disperse 2 g of bamboo charcoal in 100 ml of water. After stirring for 5 min, perform ultrasonic oscillation for 10 min. Add 1 g of dopamine and perform magnetic stirring, and add 1.3 g of tris(hydroxymethyl)aminomethane buffer solution to adjust the pH value of the mixed solution to 8.5. Stir for 4 h, and add 0.5 g of silver nanoparticles with a particle size of 24 nm during stirring to obtain a polydopamine-modified bamboo charcoal dispersion.

[0062] S6. Add 25 ml of 3-(trimethoxysilyl)propylhexadecyldimethylammonium chloride to the polydopamine-modified bamboo charcoal dispersion, stir for 5 h, centrifuge and wash at a speed of 4000 r / min, wash with water to remove organic monomers, and vacuum dry at a temperature of 60 °C to obtain modified bamboo charcoal.

[0063] S7. Add 1.1 g of modified bamboo charcoal to 220 g of a urea / tetrabutylammonium hydroxide mixed solvent (mass ratio is 2:5, and the tetrabutylammonium hydroxide solution is a 40% aqueous solution), stir to disperse the solvent evenly, and add 12.5 g of crushed bamboo pulp to the above mixed solvent and stir to dissolve to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution.

[0064] S8. Centrifuge the modified bamboo charcoal regenerated cellulose fiber spinning solution to remove air bubbles, perform wet spinning, and pass through a coagulation bath, a first drawing roller, a water washing bath, a second drawing roller, and a drying oven in sequence to obtain modified bamboo charcoal / regenerated cellulose composite fibers; the coagulation bath is a mixed solution of citric acid, sodium citrate, ethylene glycol and water, with a mass ratio of 14:5:80:110, the temperature of the coagulation bath is 25 °C, the solution in the cleaning tank is water, the first drawing ratio is 1.1, the second drawing ratio is 1.0, and the drying temperature is 80 °C.

[0065] Example 2

[0066] A method for preparing bamboo charcoal / regenerated cellulose composite fibers, comprising the following steps:

[0067] S1. Wash the bamboo, and dry it at a temperature of 60 °C for 4 h.

[0068] S2. The dried bamboo is treated in a nitrogen atmosphere at a temperature of 260 °C for 1.5 h, then heated to 520 °C and treated for 2 h to complete carbonization. After the carbonized bamboo charcoal is gradually cooled from 520 °C to 50 °C, a bamboo charcoal blank is obtained.

[0069] S3. The bamboo charcoal blank is washed to neutrality and dried at a temperature of 80 °C for 2 h to obtain bamboo charcoal with a carbon-nitrogen ratio of 92.18.

[0070] S4. The bamboo charcoal with a carbon-nitrogen ratio of 92.18 is put into a high-energy ball mill and milled for 5 h. After milling, it is passed through a sieve with a particle size of 2 μm. 10 g of the refined bamboo charcoal powder is mixed with 1000 ml of water and centrifugally washed and circulated 2 times at a speed of 4000 r / min. The washed bamboo charcoal is dried in an oven to obtain bamboo charcoal particles.

[0071] S5. 2 g of bamboo charcoal is dispersed in 100 ml of water. After stirring for 5 min, it is ultrasonically oscillated for 10 min. 1 g of dopamine is added and magnetically stirred, and 1.3 g of tris(hydroxymethyl)aminomethane buffer solution is added to adjust the pH value of the mixed solution to 8.5. Stir for 4 h, and 0.5 g of zinc oxide nanoparticles with a particle size of 24 nm is added during stirring to obtain a polydopamine-modified bamboo charcoal dispersion.

[0072] S6. 25 ml of 3-(trimethoxysilyl)propylhexadecyldimethylammonium chloride is added to the polydopamine-modified bamboo charcoal dispersion, stirred for 5 h, centrifugally washed at a speed of 4000 r / min, washed with water to remove organic monomers, and vacuum dried at a temperature of 60 °C to obtain modified bamboo charcoal.

[0073] S7. 1.1 g of modified bamboo charcoal is added to a mixed solvent of 240 g of NaOH / urea / water (mass ratio 7:12:81), stirred to disperse the solvent evenly, and 12 g of crushed bamboo pulp is added to the above mixed solvent and stirred to dissolve to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution.

[0074] S8. After the modified bamboo charcoal regenerated cellulose fiber spinning solution is vacuum degassed, dry-wet spinning is carried out, passing through an air layer, a coagulation bath, a first drawing roller, a water washing bath, a second drawing roller, and a drying oven in sequence to obtain modified bamboo charcoal / regenerated cellulose composite fibers; the height of the air layer is 10 mm, the coagulation bath is a mixed solution of citric acid, sodium citrate, ethylene glycol and water with a mass ratio of 14:5:80:110, the temperature of the coagulation bath is 25 °C, the solution in the cleaning tank is water, the first drawing ratio is 1.2, the second drawing ratio is 1.0, and the drying temperature is 80 °C.

[0075] In order to verify the successful acquisition of the modified bamboo charcoal / regenerated cellulose composite fibers in Example 1 and Example 2 Figure 1(a) shows the microscopic surface morphology of the bamboo charcoal fiber prepared in Example 1 of the present invention, Figure 1 (b) shows the microscopic surface morphology of the bamboo charcoal fiber prepared in Example 2 of the present invention; Figure 2 (a) and (b) respectively show the microscopic morphologies of the transverse and vertical cross-sections of the bamboo charcoal fiber prepared in Example 1 of the present invention, Figure 2 (c) and (d) respectively show the microscopic morphologies of the transverse and vertical cross-sections of the bamboo charcoal fiber prepared in Example 2 of the present invention; The modified bamboo charcoal / regenerated cellulose composite fiber of the present invention has a large specific surface area and pore volume, and there are a large number of micropores and mesopores. The prepared modified bamboo charcoal regenerated cellulose fiber has excellent adsorption performance.

[0076] Example 3

[0077] This example is basically the same as Example 1, the difference is that: in step S1: the bamboo is washed and dried at a temperature of 80°C for 3 h; in step S3: the bamboo charcoal blank is washed to neutral and dried at a temperature of 80°C for 3 h to obtain bamboo charcoal with a carbon-nitrogen ratio of 98.34.

[0078] Example 4

[0079] This example is basically the same as Example 1, the difference is that: in step S2: the dried bamboo is treated at a temperature of 300°C for 2 h in a nitrogen atmosphere, heated to 600°C, and treated for 3 h to complete carbonization. After the carbonized bamboo charcoal is gradually cooled from 600°C to 60°C, a bamboo charcoal blank is obtained; finally, bamboo charcoal with a carbon-nitrogen ratio of 135.42 is obtained.

[0080] Example 5

[0081] This example is basically the same as Example 1, the difference is that: in step S2: the dried bamboo is treated at a temperature of 230°C for 1 h in a nitrogen atmosphere, heated to 450°C, and treated for 3 h to complete carbonization. After the carbonized bamboo charcoal is gradually cooled from 450°C to 50°C, a bamboo charcoal blank is obtained; finally, bamboo charcoal with a carbon-nitrogen ratio of 86.25 is obtained.

[0082] Comparative Example 1

[0083] This comparative example is basically the same as Example 1, with the difference that: there is no bamboo charcoal, and the preparation includes the following steps: Add 12.5 g of crushed bamboo pulp into 220 g of a urea / tetrabutylammonium hydroxide mixed solvent (mass ratio is 2:5, and the tetrabutylammonium hydroxide solution is a 40% aqueous solution), stir and dissolve to obtain a spinning solution; Centrifuge the spinning solution to remove air bubbles, and perform wet spinning, passing through a coagulation bath, a first drawing roller, a water washing bath, a second drawing roller, and a drying oven in sequence to obtain fibers; The coagulation bath is a mixed solution of citric acid, sodium citrate, ethylene glycol, and water, with a mass ratio of 14:5:80:110, the coagulation bath temperature is 25 °C, the cleaning tank solution is water, the first drawing ratio is 1.1, the second drawing ratio is 1.0, and the drying temperature is 80 °C.

[0084] Comparative Example 2

[0085] This comparative example is basically the same as Example 1, with the difference that: there are no steps S5 and S6, and step S7 is: Add 1.1 g of bamboo charcoal particles into 220 g of a urea / tetrabutylammonium hydroxide mixed solvent (mass ratio is 2:5, and the tetrabutylammonium hydroxide solution is a 40% aqueous solution), stir to disperse the solvent evenly, add 12.5 g of crushed bamboo pulp into the above mixed solvent, stir and dissolve to obtain a bamboo charcoal regenerated cellulose fiber spinning solution.

[0086] Comparative Example 3

[0087] This comparative example is basically the same as Example 1, with the difference that: step S6 is: Centrifuge and wash the polydopamine-modified bamboo charcoal dispersion at a speed of 4000 r / min, wash it with water to remove organic monomers, and vacuum dry it at a temperature of 60 °C to obtain modified bamboo charcoal.

[0088] Comparative Example 4

[0089] This comparative example is basically the same as Example 1, with the difference that: step S5 is: Disperse 2 g of bamboo charcoal in 100 ml of water, stir for 5 min, then perform ultrasonic oscillation for 10 min, add 1 g of dopamine for magnetic stirring, and add 1.3 g of tris(hydroxymethyl)aminomethane buffer solution to adjust the pH value of the mixed solution to 8.5, stir for 4 h to obtain a polydopamine-modified bamboo charcoal dispersion.

[0090] Comparative Example 5

[0091] This comparative example is basically the same as Example 1, with the difference that: there are no steps S1, S2, and S3, and step S4 is: Put commercially available bamboo charcoal with a carbon-nitrogen ratio of 23.63 into a high-energy ball mill and ball mill for 5 h. After grinding, pass through a particle size of 2 μm, take 10 g of the refined bamboo charcoal powder and mix it with 1000 ml of water, centrifuge and wash it at a speed of 4000 r / min for 2 cycles, and dry the washed bamboo charcoal in a drying oven to obtain bamboo charcoal particles.

[0092] Comparative Example 6

[0093] This comparative example is basically the same as Example 1, the difference is: there are no steps S1, S2 and S3, and step S4 is: put commercially available bamboo charcoal with a carbon-nitrogen ratio of 158.93 into a high-energy ball mill and ball mill for 5 h. After grinding, sieve with a particle size of 2 μm, take 10 g of the refined bamboo charcoal powder and mix it with 1000 ml of water, centrifuge and wash in a cycle at a speed of 4000 r / min for 2 times, and dry the washed bamboo charcoal in a drying oven to obtain bamboo charcoal particles.

[0094] Comparative Example 7

[0095] This comparative example is basically the same as Example 1, the difference is: in step S5, the pH value of the mixed solution is adjusted to 5.8.

[0096] Comparative Example 8

[0097] This comparative example is basically the same as Example 1, the difference is: in step S5, the pH value of the mixed solution is adjusted to 10.

[0098] Performance detection: The fibers obtained in the above Examples 1-5 and Comparative Examples 1-8 were successively subjected to performance tests of antibacterial property, elongation at break and breaking strength.

[0099] Antibacterial property: Place 3-mm circular antibacterial test fibers on a bacterial culture dish, and after culturing for 12 h, observe and measure their prevention and treatment efficacy.

[0100] Elongation at break and breaking strength: Detection was carried out with reference to GB / T 14337-2008 "Chemical Fibers: Test Method for Tensile Properties of Staple Fibers".

[0101] The performance test results of antibacterial property, elongation at break and breaking strength of Examples 1-5 and Comparative Examples 1-8 are shown in Table 1.

[0102] Table 1:

[0103]

[0104]

[0105] As can be seen from the test results in Table 1, by comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be known that in Example 1 of the present invention, compared with the unadded bamboo charcoal and the unmodified bamboo charcoal, the high-density modification of polydopamine on the surface of the bamboo charcoal material can significantly increase the density of active groups on the surface of the bamboo charcoal particles, which is beneficial to improving the grafting efficiency of the polysiloxane quaternary ammonium salt after secondary modification. At the same time, by utilizing the strong binding of its modification effect with the nanoparticles, the number of active sites on the bamboo charcoal surface is increased, further improving the grafting efficiency of the bamboo charcoal and the polysiloxane quaternary ammonium salt, realizing the interaction between the functional bamboo charcoal filler and the matrix and the dispersibility in the matrix. Therefore, the prepared modified bamboo charcoal / regenerated cellulose composite fiber has excellent antibacterial properties and mechanical properties.

[0106] By comparing Example 1 with Example 3, it can be known that in the preparation of bamboo charcoal, the pretreatment of bamboo drying and the post-treatment of cleaning and drying of the bamboo charcoal blank have little effect on the carbon-nitrogen ratio of the prepared bamboo charcoal. It is mainly to remove moisture and clean, affecting the moisture content and cleanliness of the bamboo, and having little direct impact on the carbon-nitrogen ratio. By comparing Example 1 with Example 4 and Example 5, it can be known that as the carbonization temperature increases, the organic matter in the bamboo will undergo more intense pyrolysis and polycondensation reactions, which can promote the release of non-carbon elements in the form of gas, thereby increasing the carbon content and decreasing the nitrogen content in the bamboo charcoal, and then increasing the carbon-nitrogen ratio. On the contrary, a lower carbonization temperature will slow down the rate of pyrolysis and polycondensation reactions, causing more nitrogen elements to remain in the bamboo charcoal, thus decreasing the carbon-nitrogen ratio. At the same time, extending the carbonization time can make the pyrolysis and polycondensation reactions proceed more fully, which is beneficial to the further release of non-carbon elements, and a shorter carbonization time is not sufficient to effectively release all non-carbon elements, easily resulting in a relatively high nitrogen content and a low carbon-nitrogen ratio in the bamboo charcoal. Therefore, by changing the temperature and treatment time during pre-carbonization and carbonization, the carbon-nitrogen ratio of the bamboo charcoal can be effectively regulated.

[0107] By comparing Example 1 with Comparative Examples 3 and 4, it can be seen that the bamboo charcoal with a high carbon-nitrogen ratio has more micropores, specific surface area and unsaturated bonds, which helps the deposition of polydopamine on the surface of the bamboo charcoal to be more uniform, thereby increasing the available space of the surface active groups, and the bamboo charcoal with a high carbon-nitrogen ratio has more carbon-based active sites on the surface, which can serve as the catalytic center of the polymerization reaction of polydopamine, so that the carbon atoms in the bamboo charcoal can form stronger chemical bonds with the nitrogen atoms in the polydopamine, which can make the interaction between the bamboo charcoal and the polydopamine stronger, thereby enhancing the interfacial bonding force between the bamboo charcoal and the polydopamine, and thus helping Improve the grafting effect, further improve its antibacterial and mechanical properties. At the same time, bamboo charcoal with too low or too high carbon-nitrogen ratio will have a certain impact on the subsequent modification and grafting effect, which will further affect the antibacterial and mechanical properties. Because bamboo charcoal with too low carbon-nitrogen ratio has fewer surface active sites and more defects or vacancies in the carbon skeleton, the bamboo charcoal is easily damaged during the modification and grafting process, resulting in a decrease in performance. Too high a carbon-nitrogen ratio will also destroy the carbon skeleton structure of bamboo charcoal, and affect the attachment and distribution of the modified and grafted molecules on the surface of bamboo charcoal, thereby resulting in a decrease in mechanical properties and affecting its antibacterial properties.

[0108] By comparing Example 1 with Comparative Example 5, it can be seen that the polysiloxane quaternary ammonium salt during the secondary modification not only enhances the hydrophilicity and antibacterial properties of the bamboo charcoal, but the long-chain structure of the polysiloxane quaternary ammonium salt also helps to improve the dispersibility of the bamboo charcoal in the regenerated cellulose matrix, thereby also having a certain impact on the mechanical properties of the fiber. Because the polysiloxane quaternary ammonium salt molecule contains a quaternary ammonium group, the polydopamine layer formed by dopamine on the surface of the bamboo charcoal has good adhesion and reactivity. When the polysiloxane quaternary ammonium salt is grafted to the surface of the bamboo charcoal through chemical bonds, the quaternary ammonium group therein is firmly fixed on the bamboo charcoal particles and dispersed into the regenerated cellulose fibers along with the bamboo charcoal particles, effectively improving the antibacterial properties of the fibers. At the same time, the functional groups in the polysiloxane quaternary ammonium salt molecules can form hydrogen bonds or ionic bonds with groups such as hydroxyl groups on the surface of the bamboo charcoal and the regenerated cellulose fibers, which not only enhances the compatibility between the bamboo charcoal and the regenerated cellulose, but also improves the interfacial bonding force between them, thereby better improving the mechanical properties of the fibers.

[0109] From the comparison between Example 1, Example 2 and Comparative Example 6, it can be known that the functional nanoparticles endow the composite fibers with additional antibacterial and mechanical properties. Due to the difference between the positive charge on the surface of the functional nanoparticles and the negative charge on the bacterial cell wall, the nanoparticles can strongly adsorb on the surface of bacteria and disrupt the integrity of the bacterial cell membrane through electrostatic interaction. At the same time, the active sites on the surface of the nanoparticles can react with biomolecules inside the bacteria to further inhibit or kill bacteria. Moreover, the functional nanoparticles have a large specific surface area and rich surface chemical properties, enabling the nanoparticles to form strong interactions with the active sites on the surface of bamboo charcoal, increasing the number of active sites on the surface of bamboo charcoal, providing more grafting positions for polydimethylsiloxane quaternary ammonium salt, thus improving the grafting efficiency and further enhancing the antibacterial and mechanical properties.

[0110] From the comparison between Example 1 and Comparative Example 7, it can be known that in an acidic environment, the self-polymerization process of dopamine is inhibited, resulting in hindered formation of polydopamine, making the antibacterial agent on the surface of the nanoparticles unable to be effectively fixed or unevenly distributed. Moreover, the functional nanoparticles are prone to dissolution and structural damage in an acidic environment, thus reducing the overall antibacterial performance and leading to a decline in mechanical properties. In an alkaline environment, functional groups such as amino and catechol groups in dopamine molecules are more likely to be deprotonated to form negatively charged ions, which can undergo electrostatic interaction and hydrogen bond interaction to promote the self-polymerization ability of dopamine, enabling it to be applied to the surface modification of functional nanoparticles, helping to stabilize the charge on the surface of the nanoparticles, significantly enhancing their stability and dispersibility in aqueous solution, preventing agglomeration, and thus achieving the synergistic effect of dopamine, functional nanoparticles and polydimethylsiloxane quaternary ammonium salt, effectively improving the antibacterial effect and mechanical properties. From the comparison between Example 1 and Comparative Example 8, it can be known that although an alkaline environment is beneficial to the self-polymerization of dopamine and the fixation of the antibacterial agent, an overly alkaline environment is prone to cause hydrolysis or decomposition reactions of the antibacterial agent, and at the same time affect the stability of polydimethylsiloxane quaternary ammonium salt, thus reducing the antibacterial activity and its mechanical properties.

[0111] Based on the ideal embodiments of the present invention as inspiration, through the above description, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0112] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of bamboo charcoal / regenerated cellulose composite fiber, characterized in that, It includes the following steps: S1. Crush and sieve bamboo charcoal, wash it with water and dry it to obtain bamboo charcoal particles. S2. Disperse bamboo charcoal in water, add dopamine and tris (hydroxymethyl) aminomethane, adjust the pH value, and add functional nanoparticles during stirring to obtain a polydopamine-modified bamboo charcoal dispersion. S3. Add siloxane quaternary ammonium salt to the polydopamine-modified bamboo charcoal dispersion, carry out surface in-situ polymerization, then centrifuge, wash and dry to obtain modified bamboo charcoal. S4. Mix the modified bamboo charcoal, cellulose and solvent to obtain a modified bamboo charcoal regenerated cellulose fiber spinning solution. S5. The modified bamboo charcoal regenerated cellulose fiber spinning solution is wet-spun and then dried to obtain modified bamboo charcoal / regenerated cellulose composite fibers. In the step of S4, the solvent is one of tetrabutylammonium hydroxide / urea solution, alkali / urea solution, N-methylmorpholine-N-oxide solution or 1-allyl-3-methylimidazolium chloride ionic liquid.

2. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S1, the preparation of the bamboo charcoal includes the following steps: S11. Wash bamboo materials and dry them at a temperature of 50-80 °C for 3-6 h. S12. Treat the dried bamboo materials in an anaerobic atmosphere at a temperature of 230-300 °C for 1-2 h, then raise the temperature to 450-600 °C and treat for 2-4 h. After gradually cooling the carbonized bamboo charcoal from the highest calcination temperature to 50-60 °C, obtain bamboo charcoal blanks. S13. Wash the bamboo charcoal blanks to neutrality and dry them at a temperature of 60-100 °C for 1-3 h to obtain bamboo charcoal with a carbon-nitrogen ratio of 86.25-135.

42.

3. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, wherein: In the step of S1, the bamboo charcoal crushing includes mechanical ball milling and air jet milling, and the grinding time is 2-8 h; the particle size of the crushed bamboo charcoal is 1-20 μm.

4. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S2, the functional nanoparticles are one of silver nanoparticles or zinc oxide nanoparticles, with a particle size of 24-100 nm; the mass ratio of the bamboo charcoal, the dopamine, the tris (hydroxymethyl) aminomethane, the functional nanoparticles and the water is 1-3:0.25-2.4:0.25-3.5:0.5-1.5:100; the pH value is 7-9; the stirring and modification time is 2-6 h.

5. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S3, the siloxane quaternary ammonium salt is one of 3-(trimethoxysilyl) propyl hexadecyl dimethyl ammonium chloride, 3-(trimethoxysilyl) propyl octadecyl dimethyl ammonium chloride, 3-(triethoxysilyl) propyl hexadecyl dimethyl ammonium chloride or 3-(triethoxysilyl) propyl octadecyl dimethyl ammonium chloride.

6. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S3, the mass ratio of the siloxane quaternary ammonium salt to the bamboo charcoal is 15-30:1; the time of the surface in-situ polymerization is 4-8 h.

7. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, wherein: In the step of S4, the mass ratio of the modified bamboo charcoal, the cellulose and the solvent is 0.1-0.3:3-8:

85.

8. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S4, the cellulose is one of bamboo pulp, cotton pulp, wood pulp or hemp pulp.

9. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S5, before wet spinning, centrifuge the modified bamboo charcoal regenerated cellulose fiber spinning solution to remove air bubbles.

10. The preparation method of a bamboo charcoal / regenerated cellulose composite fiber according to claim 1, characterized in that: In the step of S5, the modified bamboo charcoal / regenerated cellulose composite fiber is drawn twice, and the draft ratio is 0.9 to 1.4.

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