Phloem antibacterial fiber, its preparation method and application

Abstract

The application provides a bast antibacterial fiber and a preparation method and application thereof, and belongs to the field of bast fiber modification. The preparation method of the bast antibacterial fiber comprises the following steps: pretreating bast fibers by alkali to obtain alkalized cellulose fibers; treating the alkalized cellulose fibers by an alcohol / water system to obtain cellulose fibers with micro-nano structure lignin adhered; and reacting the cellulose fibers with micro-nano structure lignin adhered with metal bromide under acidic conditions to obtain the bast antibacterial fiber. The application only regulates the morphological structure, distribution and quantity of lignin originally present on the surface of the fiber to improve the antibacterial property of the fiber, and the excellent moisture absorption, air permeability and hand feeling and other comfort properties of the bast fiber are not weakened, so that the bast antibacterial fiber with excellent structure, excellent and stable performance is obtained. The preparation process is simple, easy to operate, easy to manage and green and environmentally friendly, and the obtained bast antibacterial fiber and fabric are harmless to the human body.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bast fiber modification, and particularly relates to a bast antibacterial fiber and a preparation method and application thereof. BACKGROUND

[0002] The bast fiber has a high carbon storage (26.03 tCO2 / ha) and contains various antibacterial phenolic components in the molecular structure, and is a high-strength fiber with antibacterial performance, which has great application value in high-end fields such as medical protective clothing, military uniforms, aerospace suits and special work clothes. The bast fiber needs to be treated to obtain soft spinning fiber to improve comfort in practical application. However, it is inevitable to remove part of the lignin in the molecular structure of the bast fiber which is hard but rich in antibacterial phenolic substances during the preparation of the soft spinning fiber, thereby weakening the antibacterial performance of the bast fiber.

[0003] Currently, post-finishing technology is usually used to improve the antibacterial performance of the soft spinning fiber. Although this method can improve the antibacterial performance, additional antibacterial substances need to be introduced in the post-finishing process, which changes the surface physicochemical properties of the soft fiber, weakens the moisture absorption, air permeability and hand feeling and other comfort, and the process steps of the post-finishing process are relatively complicated, which increases the difficulty and cost in actual production and application to a certain extent. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a bast antibacterial fiber and a preparation method and application thereof, aiming to solve the technical problems that the existing post-finishing technology needs to introduce additional antibacterial substances, thereby affecting the moisture absorption, air permeability and hand feeling and other comfort of the fiber, and the process steps are complicated.

[0005] In a first aspect, the embodiments of the present application provide a preparation method of a bast antibacterial fiber, comprising the following steps:

[0006] S1, pretreating a bast fiber with alkali to obtain an alkali cellulose fiber;

[0007] S2, treating the alkali cellulose fiber with an alcohol / water system to obtain a cellulose fiber with micro-nano structure lignin adhesion;

[0008] S3, reacting the cellulose fiber with micro-nano structure lignin adhesion with a metal bromide under acidic conditions to obtain a bast antibacterial fiber.

[0009] In the technical scheme of the embodiment of the application, first, the bast fiber is pretreated with alkali to make the bast fiber degummed and softened, improve the comfort while not affecting the moisture absorption and air permeability of the bast fiber, and obtain the alkalized cellulose fiber with blocky lignin attached to the surface; then, the alkalized cellulose fiber is treated in an alcohol / water system to further break the blocky lignin molecular chain on the surface of the alkalized cellulose fiber while in-situ micro-nano regulating the structure, distribution and content of residual lignin in the alkalized cellulose fiber, so that the appropriate micro-nano structure lignin is uniformly distributed on the surface of the cellulose fiber, and the cellulose fiber with micro-nano structure lignin is obtained; finally, the lignin on the surface of the fiber is modified by phenolation under acidic conditions, and the bast antibacterial fiber with rich phenolic hydroxyl groups is obtained.

[0010] In some embodiments, in step S2, the volume ratio of alcohol to water in the alcohol / water system is 20%-80%:80%-20%; and in the cellulose fiber with micro-nano structure lignin, the mass concentration of lignin is 5%-15%.

[0011] In this embodiment, by reasonably controlling the volume ratio of alcohol to water in the alcohol / water system, the breaking of the lignin molecular chain is ensured to proceed smoothly while the structure, distribution and content of residual lignin in the alkalized cellulose fiber are reasonably micro-nano regulated, and under the premise of not affecting the moisture absorption, air permeability and hand feeling of the bast fiber, favorable conditions are provided for the subsequent phenolation modification, so that the cellulose fiber with excellent micro-nano structure lignin is obtained.

[0012] In some embodiments, step S2 specifically comprises: soaking the alkalized cellulose fiber in the alcohol / water system with a bath ratio of 1:(30-100) for reaction, the reaction temperature is 50-150 DEG C, and the reaction time is 30-60 min.

[0013] In this embodiment, first, the alkalized cellulose fiber is fully swollen by controlling the bath ratio in a suitable range; then, the temperature and time of the reaction are reasonably controlled to control the degree of breaking of the lignin molecular chain, and the structure, distribution and content of residual lignin in the alkalized cellulose fiber are in-situ micro-nano regulated, so that the cellulose fiber with micro-nano structure lignin is obtained.

[0014] In some embodiments, step S3 specifically comprises: soaking the cellulose fiber with micro-nano structure lignin in a metal bromide solution with a mass concentration of 40%-60% with a bath ratio of 1:(20-100) for reaction, the reaction temperature is 100-120 DEG C, and the reaction time is 60-120 min.

[0015] In this embodiment, first, the cellulose fiber with micro-nano structure lignin is fully swollen by controlling the bath ratio in a suitable range; then, the concentration of the metal bromide solution and the temperature and time of the substitution reaction are reasonably controlled to smoothly realize the phenolation modification of the lignin and improve the antibacterial performance of the fiber.

[0016] In some embodiments, the pH value of the acidic condition is 4.5-7.2.

[0017] In this embodiment, by reasonably adjusting the pH value of the metal bromide reaction solution, the phenolic modification reaction is ensured to proceed smoothly, thereby obtaining the bast antibacterial fiber with rich phenolic hydroxyl groups.

[0018] In some embodiments, the step S1 specifically comprises: reacting the bast fiber in an alkali solution with a mass concentration of 20%-30% at a bath ratio of 1:(30-100), a reaction temperature of 80-100°C, and a reaction time of 1-5h.

[0019] In this embodiment, by controlling the bath ratio within a suitable range, the bast fiber is fully swollen; then by reasonably controlling the temperature and time of the reaction, an appropriate amount of lignin is selectively removed, thereby providing favorable conditions for subsequent in-situ micro-nano regulation.

[0020] In some embodiments, the bast fiber comprises one or more of ramie fiber, flax fiber, jute fiber, hemp fiber, loobal fiber, and banana fiber.

[0021] In this embodiment, by reasonably selecting the types of the bast fiber, the alkali pretreatment, in-situ micro-nano regulation, and phenolic modification can be smoothly performed on the fiber surface, thereby obtaining the bast antibacterial fiber with high air permeability, high comfort, and high antibacterial property.

[0022] In a second aspect, the embodiments of the present application provide a bast antibacterial fiber prepared by the preparation method of the bast antibacterial fiber provided in the first aspect of the present application.

[0023] In the technical solution of the embodiments of the present application, the bast antibacterial fiber is prepared by using the specific method of the present application, and under the premise of not weakening the excellent moisture absorption, air permeability, and hand feeling comfort of the bast fiber, the bast antibacterial fiber with excellent structure, outstanding and stable performance, and no harm to the human body is obtained.

[0024] In some embodiments, the antibacterial rate of the bast antibacterial fiber against Staphylococcus aureus is as high as 97.73%, and the antibacterial rate after washing for 50 times is as high as 91.44%; the antibacterial rate against Escherichia coli is as high as 98.70%, and the antibacterial rate after washing for 50 times is as high as 92.65%; the strength is as high as 34.2 cN / tex, the air permeability of the fiber fabric is as high as 847 mm / s, and the bending stiffness is only 1.85 cN·cm 2 .

[0025] In this embodiment, the obtained bast antibacterial fiber has excellent and durable antibacterial performance, excellent mechanical performance, good air permeability, and moderate softness.

[0026] In a third aspect, the embodiments of the present application provide application of the bast antibacterial fiber in the antibacterial functional textile.

[0027] In the technical scheme of the embodiments of the present application, the bast antibacterial fiber is applied in the antibacterial functional textile, thereby obtaining the functional textile with high antibacterial property, high moisture absorption and air permeability, and comfort.

[0028] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application, the embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical scheme of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0030] Figure 1 Preparation principle diagram of the bast antibacterial fiber in the embodiments of the present application;

[0031] Figure 2 Scanning electron microscope diagram of the hemp bast fiber used in the embodiment 1 of the present application, the scale is 100 um;

[0032] Figure 3 Scanning electron microscope diagram of the single hemp bast fiber after the hemp bast fiber in the embodiment 1 of the present application is sequentially pretreated by alkali and treated by alcohol / water system, the scale is 10 um;

[0033] Figure 4 Scanning electron microscope diagram of the hemp bast fiber after the hemp bast fiber in the embodiment 1 of the present application is sequentially pretreated by alkali and treated by alcohol / water system, the scale is 500 nm;

[0034] Figure 5 Particle size distribution diagram of the lignin of the micro-nano structure on the fiber surface after the hemp bast fiber in the embodiment 1 of the present application is sequentially pretreated by alkali and treated by alcohol / water system.

[0035] Figure 6 Scanning electron microscope diagram of the lignin precipitate in the residual liquid of the alcohol / water system after reaction in the embodiment 1 of the present application after separation and purification, the scale is 1 um;

[0036] Figure 7 Transmission electron microscope diagram of the lignin precipitate in the residual liquid of the alcohol / water system after reaction in the embodiment 1 of the present application after separation and purification, the scale is 200 nm;

[0037] Figure 8 Figure 1 is a particle size distribution diagram of the lignin precipitated from the residual liquor of the alcohol / water system after the reaction in Example 1 of the present application. DETAILED DESCRIPTION

[0038] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0040] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] Lignified fiber has the characteristics of high strength and antibacterial property, and is widely used in high-end fields. Lignified fiber needs to be softened during use to improve comfort, but softening treatment will reduce its antibacterial property. The common finishing technology for improving the antibacterial property of soft textile fiber, i.e. softened lignified fiber, needs to introduce additional antibacterial substances, which affects the surface physical and chemical properties of the fiber, reduces its moisture absorption, air permeability and hand feeling, and the process steps of the finishing process are more complicated.

[0042] In order to solve the technical problems of the existing finishing technology, which needs to introduce additional antibacterial substances to affect the moisture absorption, air permeability and hand feeling of the fiber, and the process steps are complicated, the present application provides a lignified antibacterial fiber and a preparation method thereof, wherein the lignified fiber is pretreated with alkali to soften and degum, the alcohol / water system is used to regulate the morphological structure, distribution and quantity of residual lignin originally existing on the surface of the fiber, and the lignin is modified by phenolization reaction with metal bromide, so that the excellent lignified antibacterial fiber with excellent structure, outstanding performance and stability is obtained without weakening the excellent moisture absorption, air permeability and hand feeling of the lignified fiber.

[0043] Please refer to Figure 1In a first aspect, the embodiments of the present application provide a preparation method of bast antibacterial fiber, comprising the following steps:

[0044] S1, pretreating the bast fiber with alkali to obtain alkali cellulose fiber;

[0045] S2, treating the alkali cellulose fiber with alcohol / water system to obtain cellulose fiber with micro-nano structure lignin adhered;

[0046] S3, reacting the cellulose fiber with micro-nano structure lignin adhered with metal bromide under acidic condition to obtain bast antibacterial fiber.

[0047] In the technical scheme of the embodiments of the present application, first, the bast fiber is pretreated with alkali to remove impurities and pectin, hemicellulose, lignin and other gum substances on the surface of the bast fiber, and the impurities are removed while the bast fiber is preliminarily degummed and softened, which improves the comfort while not affecting the air permeability, and the alkali cellulose fiber with blocky lignin adhered on the surface as shown in Figure 1 is obtained, which provides favorable conditions for preparing soft textile fiber; then, the alkali cellulose fiber after preliminary degumming is treated with alcohol / water system, the molecular chains of the blocky lignin on the surface of the alkali cellulose fiber are further destroyed and broken, and at the same time, with the breaking of the molecular chains of the lignin, the structure, distribution and content of the residual lignin in the alkali cellulose fiber are in-situ micro-nano regulated, and the specific surface area is improved, and the cellulose fiber with micro-nano structure lignin adhered as shown in Figure 1The cellulose fibers shown are uniformly distributed with an appropriate amount of micro-nano structure lignin, that is, the cellulose fibers to which the micro-nano structure lignin with a large number of active sites is adhered, provide a basis for forming more phenolic hydroxyl groups and strengthening the antibacterial performance, while the residual liquid in the alcohol / water system after the reaction contains lignin precipitates and partially degraded lignin (i.e., depolymerized solubles) that fall off the fiber surface during the bond breaking process; finally, the cellulose fibers to which the micro-nano structure lignin is adhered are reacted with metal bromide under acidic conditions, so that the C-O bond of the methoxyl group in the lignin molecular structure is broken and a phenolic hydroxyl group is formed, that is, the lignin is phenolized and modified, and a bast antibacterial fiber rich in phenolic hydroxyl groups is obtained. The present application overcomes the technical bias in the prior art of introducing additional antibacterial components, anchors the antibacterial modification target on the lignin originally present on the surface of the bast fiber, utilizes the different chemical activities of lignin and cellulose, and only regulates the morphology, structure, distribution and quantity of the lignin originally present on the fiber surface to improve the antibacterial properties of the fiber. No additional antibacterial components such as quaternary ammonium salts need to be introduced during the reaction, so that the good comfort and air permeability characteristics of natural cellulose fibers can be maintained; at the same time, by regulating the conditions of the demethoxylation and phenolization modification reaction of the metal bromide on the micro-nano structure lignin, the phenolization reaction is efficiently completed on the lignin, and the morphology and molecular structure of the cellulose are not damaged, that is, the morphology and molecular structure of the cellulose are not damaged during the entire preparation process, so that the performance of the prepared antibacterial fiber is stable. It can be seen that the present application obtains a bast antibacterial fiber with excellent structure and stable performance without weakening the excellent moisture absorption, air permeability and hand feeling of the bast fiber. The preparation process of the method is simple, easy to operate and manage, green and environmentally friendly, and the obtained bast antibacterial fiber and fabric are harmless to the human body.

[0048] Further, in some embodiments, in step S2, the volume ratio of alcohol to water in the alcohol / water system is 20%-80%:80%-20%, and the mass concentration of lignin in the cellulose fibers to which the micro-nano structure lignin is adhered is 5%-15%. Specifically, the alcohol includes one or more of methanol, ethanol, and propanol, and is preferably ethanol.

[0049] In the technical scheme of the embodiment of the present application, under the mutual coordination of the change of the ratio of alcohol to water in the alcohol / water system, the bath ratio of the alcohol / water immersion solution, the reaction time and the reaction temperature, the degree of lignin molecular chain breakage is controlled, thereby the content of lignin in the cellulose fiber to which the micro-nano structure lignin is adhered is controlled, a proper amount of lignin is uniformly adhered to the fiber surface, the comfort of the bast fiber such as moisture absorption, air permeability and hand feeling is not affected, and favorable conditions are provided for subsequent phenolic modification, thereby excellent antibacterial property is given to the bast fiber. By reasonably controlling the volume ratio of alcohol to water in the alcohol / water system, that is, controlling the change of the ratio of alcohol to water, a suitable concentration is provided for the reaction, the smooth breakage of the lignin molecular chain is ensured, and at the same time, excessive breakage or insufficient breakage of the lignin molecular chain is avoided, the structure, distribution and content of residual lignin in the alkali cellulose fiber are reasonably micro-nano regulated, and the cellulose fiber to which the micro-nano structure lignin is adhered is obtained.

[0050] Further, in some embodiments, step S2 is specifically: the alkali cellulose fiber is immersed in the alcohol / water system for reaction with a bath ratio of 1:(30-100), the reaction temperature is 50-150°C, the reaction time is 30-60 min, after the reaction is completed, the reaction solution is cooled and the fiber is taken out, washed thoroughly and dried, and the cellulose fiber to which the micro-nano structure lignin is adhered is obtained. Preferably, the bath ratio is 1:(40-80), the reaction temperature is 70-120°C, and the reaction time is 40-50 min. Specifically, the bath ratio, also referred to as the liquid ratio, refers to the mass ratio of the fiber to the immersion solution in the immersion process.

[0051] In the technical scheme of the embodiment of the present application, first, by controlling the bath ratio in a suitable range, the alkali cellulose fiber is uniformly and sufficiently immersed in the alcohol / water system, the alkali cellulose fiber is sufficiently swelled, and the lignin existing on the surface of the alkali cellulose fiber is in sufficient contact with the alcohol / water system; then, the temperature and time of the reaction are reasonably controlled, that is, the degree of lignin molecular chain breakage is controlled, the blocky lignin adhered to the surface of the alkali cellulose fiber is further removed, and at the same time, the structure, distribution and content of residual lignin in the alkali cellulose fiber are in-situ micro-nano regulated, and the cellulose fiber to which the micro-nano structure lignin is adhered is obtained. In addition, the process uses a relatively large bath ratio (that is, a relatively large amount of immersion solution is used), compared with a small bath ratio, the lignin existing at different positions on the surface of the alkali cellulose fiber can be uniformly broken, so that the structures of the lignin at different positions on the fiber surface are similar, and the uniform distribution of the lignin on the fiber surface is promoted, and uniform micro-nano regulation is achieved.

[0052] Further, in some embodiments, step S3 is specifically: soaking the micro-nano structure lignin-adhered cellulose fibers in a metal bromide solution with a mass concentration of 40%-60% at a bath ratio of 1:(20-100), and reacting at a temperature of 100-120°C for 60-120 min; after the reaction, the reaction solution is cooled, the fibers are taken out, filtered, washed thoroughly, and dried to obtain the bast antibacterial fiber. Preferably, the bath ratio is 1:(40-80), the reaction temperature is 100-110°C, the reaction time is 60-90 min, and the mass concentration of the metal bromide is 40%-50%.

[0053] In the technical scheme of the embodiments of the present application, first, by controlling the bath ratio within a suitable range, the micro-nano structure lignin-adhered cellulose fibers are uniformly and sufficiently soaked in the metal bromide solution, the micro-nano structure lignin-adhered cellulose fibers are sufficiently swollen, and the lignin on the surface of the fibers is in sufficient contact with the metal bromide; then, the concentration of the metal bromide solution and the temperature and time of the substitution reaction are reasonably controlled, the C-O bond of the methoxyl group in the lignin molecular structure is fully broken and a hydroxyl group is formed, the aryl methoxyl group of the lignin is efficiently converted into a phenolic hydroxyl group, the phenolation modification of the lignin is realized, the antibacterial performance of the fibers is improved, and the bast antibacterial fiber rich in phenolic hydroxyl groups is obtained. The process uses a relatively large bath ratio, compared with a small bath ratio, the methoxyl groups in the micro-nano structure lignin at different positions on the surface of the micro-nano structure lignin-adhered cellulose fibers are fully and uniformly phenolated, thereby improving the antibacterial performance of the fibers.

[0054] Further, in some embodiments, the pH value of the acidic condition is 4.5-7.2. Specifically, an acid is added to the metal bromide solution to adjust the pH value of the metal bromide solution to the required value, wherein the acid is one or more of hydrobromic acid, hydrochloric acid, and sulfurous acid.

[0055] In the technical scheme of the embodiments of the present application, by adding an acid to the metal bromide solution to adjust the pH value of the metal bromide reaction solution, the smooth progress of the phenolation modification reaction is ensured, thereby obtaining the bast antibacterial fiber rich in phenolic hydroxyl groups.

[0056] Further, in some embodiments, step S1 is specifically: reacting the bast fibers in an alkali solution with a mass concentration of 20%-30% at a bath ratio of 1:(30-100) and a temperature of 80-100°C for 1-5 h; after the reaction, the fibers are taken out, washed thoroughly, impurities are removed, and dried to obtain the alkali-treated cellulose fibers. The washing, impurity removal, and drying can be performed using conventional processes in the art. Preferably, the bath ratio is 1:(60-80), the reaction time is 2-3 h, and the alkali includes one or more of sodium hydroxide and potassium hydroxide.

[0057] In the technical solution of the embodiment of the present application, by controlling the bath ratio within an appropriate range, the bast fibers are uniformly and fully immersed in the alkali solution of appropriate concentration, and the bast fibers are fully swollen; then the temperature and time of the reaction are reasonably controlled to fully remove impurities and selectively remove an appropriate amount of lignin, while softening the bast fibers while ensuring that an appropriate amount of block lignin is still attached to the fiber surface, providing favorable conditions for subsequent in-situ micro-nano regulation.

[0058] Further, in some embodiments, the bast fiber includes one or more of ramie fiber, flax fiber, jute fiber, hemp fiber, apocynum fiber, and banana fiber.

[0059] In the technical solution of the embodiment of the present application, by rationally selecting the type of bast fiber, alkali pretreatment, in-situ micro-nano regulation and phenolic modification are smoothly carried out on the fiber surface, thereby obtaining bast fiber with high air permeability, high comfort and high antibacterial properties.

[0060] In a second aspect, an embodiment of the present application provides a bast antibacterial fiber, which is prepared using the preparation method of the bast antibacterial fiber provided in the first aspect of the present application.

[0061] In the technical solutions of the embodiments of the present application, bast antimicrobial fibers are prepared using the specific methods of the present application. Without compromising the excellent moisture absorption, breathability, and comfort properties of the bast fibers, a bast antimicrobial fiber with excellent structure, excellent performance, stability, and harmlessness to the human body is obtained. The resulting bast antimicrobial fiber exhibits excellent antimicrobial efficacy and long-lasting antimicrobial properties. It is not only safe and environmentally friendly, but also achieves antimicrobial effects efficiently, quickly, and persistently. Furthermore, this material can be widely used in the manufacture of various textiles with antimicrobial properties and has broad application prospects in various sterilization and disinfection fields.

[0062] Furthermore, in some embodiments, the antibacterial rate of the bast antibacterial fiber against Staphylococcus aureus is as high as 97.72%, and the antibacterial rate after washing 50 times is as high as 91.44%; the antibacterial rate against Escherichia coli is as high as 98.70%, and the antibacterial rate after washing 50 times is as high as 92.65%; the strength is as high as 34.2 cN / tex, the air permeability of the fiber fabric is as high as 847 mm / s, and the bending stiffness is only 1.85 cN·cm 2 .

[0063] In the technical solution of the embodiment of the present application, the obtained bast antibacterial fiber has excellent and long-lasting antibacterial properties, excellent mechanical properties, good air permeability and moderate softness.

[0064] In a third aspect, the embodiments of the present application provide an application of bast antibacterial fiber in antibacterial functional textiles.

[0065] The technical scheme of the embodiment of the present application applies the bast antibacterial fiber to the antibacterial functional textile, especially to the high-end field textile with high antibacterial property, such as medical protective clothing, special work clothes and the like, so that the functional textile with high antibacterial property, high moisture absorption and air permeability and comfort is obtained.

[0066] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are used only to explain the present application and cannot be understood as limiting the present application. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0067] Embodiment 1

[0068] The embodiment provides a preparation method of the bast antibacterial fiber, comprising the following steps:

[0069] S1, 2.0 g of hemp bast fiber is reacted in 120 mL of a sodium hydroxide solution with a mass concentration of 20% at a bath ratio of 1:60, the reaction temperature is 100°C, the reaction time is 3 h, after the reaction is completed, the fiber is taken out, washed with distilled water for several times, the impurities on the surface of the fiber are removed by using a small air flow impurity removal machine, and the fiber is dried to constant weight in a constant temperature drying box at 40°C to obtain an alkali cellulose fiber.

[0070] The hemp bast short fiber provided by Shanghai Jiayu Textile Co., Ltd. has the following technical indexes: main body length 24.3 mm, quality length 27.88 mm, uniformity 387, short fiber rate 9.53, fiber rate above 50 mm 23.11%, fiber rate above 60 mm 11.49%, count 1724 Nm, breaking length 28.3 Km, strength 18.66 cN / tex, and strength 3.49 g / tex.

[0071] S2, 1.5 g of the alkali cellulose fiber prepared in step S1 is added to 120 mL of an ethanol / water system at a bath ratio of 1:80, after the fiber is fully swelled, the reaction is carried out at 70°C for 45 min in a rotary sample dyeing machine, the fiber is taken out after the reaction solution is cooled, washed with distilled water for several times, and dried to constant weight in a constant temperature drying box at 40°C to obtain a cellulose fiber with micro-nano structure lignin adhesion.

[0072] The volume ratio of ethanol to water in the ethanol / water system is 30%:70%, and the mass concentration of lignin in the obtained cellulose fiber with micro-nano structure lignin adhesion is 9%.

[0073] S3, hydrobromic acid was added to the lithium bromide solution, the pH value of the lithium bromide solution was adjusted to 5.4, 1.0 g of the micro-nano structured lignin adhered cellulose fiber prepared in step S2 was weighed, and was immersed in a lithium bromide solution with a mass concentration of 50% at a bath ratio of 1:80, the fiber was fully swelled, and then was heated to 100 DEG C in an oil bath for 90 min, after the reaction was completed, the fiber and the solution mixture were cooled in ice water, and were filtered on a glass funnel, the fiber was collected, was washed several times with deionized water, and was dried in a constant temperature drying oven at 40 DEG C until the weight was constant, to obtain the hemp bast fiber with antibacterial property. The hemp bast fiber with antibacterial property obtained has a white appearance, no special pungent smell, is harmless to human body, has good environmental protection property, and has good morphology.

[0074] As shown in the SEM images in Figure 2 , before the alkali pretreatment, the hemp bast fiber used in example 1 is tightly wrapped by lignin and other non-cellulose substances, and the fiber has a fiber bundle morphology. As shown in the SEM images in Figure 3 , after the alkali pretreatment and the alcohol / water system treatment, the original blocky and disordered lignin on the surface of the hemp bast fiber is cracked into micro-nano sized lignin, and the micro-nano structured lignin is uniformly loaded on the surface of the hemp bast fiber, as can be seen from Figure 5 , the size of the micro-nano structured lignin is concentrated between 200-300 nm. As can be seen from Figure 4 , the micro-nano structured lignin also exists between the adjacent two fibers, and is used to connect different fibers to improve the strength of the fiber and meet the spinnable length requirement.

[0075] As shown in the SEM images in Figure 6 and the TEM images in Figure 7 , the lignin precipitated from the residual solution of the alcohol / water system after the reaction is separated and purified to obtain the micro-nano structured lignin, and as can be seen from the particle size distribution in Figure 8 , the average diameter of the spherical residual lignin is 249.7 nm.

[0076] Examples 2-3 and comparative examples 1-2

[0077] A method for preparing a bast fiber with antibacterial property, compared with example 1, the difference lies in that the concentration of the sodium hydroxide solution, i.e. the concentration of the lye, is different in step S1, and other aspects are substantially the same as those in example 1, which will not be repeated here.

[0078] The hemp bast fibers with antibacterial property prepared in examples 1-3 and comparative examples 1-2 and the fabrics thereof were tested for performance, and the results are shown in table 1.

[0079] The antibacterial rate test was performed according to GB / T20994.2-2007 absorption method. The control sample of Staphylococcus aureus (hereinafter referred to as "golden ball") and Escherichia coli in Example 1 had 44 and 77 bacterial colonies, respectively. After inoculation with the Hanma bast antibacterial fiber prepared in Example 1, the number of bacterial colonies in the golden ball liquid and the Escherichia coli liquid was 1, so the antibacterial rate of the Hanma bast antibacterial fiber to the golden ball and the Escherichia coli was 97.73% and 98.70%, respectively, and the antibacterial effect was good. The untreated original Hanma bast fiber had an antibacterial rate of 0 to the golden ball and the Escherichia coli.

[0080] The obtained Hanma bast antibacterial fiber was cut into 20 mm fiber segments, ensuring no damage, and after moisture conditioning treatment (equilibrium at 20°C and 65% humidity for 24h), the strength of a single fiber was detected using a universal material testing machine (tension machine).

[0081] Meanwhile, the obtained Hanma bast antibacterial fiber was woven into fabric, and a 10 cm x 10 cm fabric sample 1 was cut out, and the air permeability of the fiber fabric was detected using an air permeability tester; at the same time, a 2.5 cm x 15 cm fabric sample 2 was cut out, and the bending stiffness of the fiber fabric was detected using a cantilever beam bending stiffness instrument.

[0082] Table 1 Performance of Hanma bast antibacterial fiber and its fabric in Examples 1-3 and Comparative Examples 1-2

[0083]

[0084] As can be seen from Table 1, within a certain range, as the concentration of the alkali solution increases, the antibacterial rate and strength of the obtained Hanma bast antibacterial fiber fluctuate within a certain range, and the antibacterial rate of the fiber to Escherichia coli and Staphylococcus aureus is greater than 86%, which belongs to a fiber material with excellent antibacterial performance, and the overall performance of the fiber is good. The air permeability and bending stiffness of the woven fabric fluctuate within a certain range. When the concentration of the alkali solution is too high or too low, the comprehensive performance of the obtained Hanma bast antibacterial fiber and fabric is weakened, which may be because the concentration of the alkali solution is too high or too low, which affects the destruction of lignin during alkali pretreatment, thereby affecting the structure of the alkali cellulose fiber, and further affecting the micro-nano regulation of the lignin structure by the subsequent alcohol / water system treatment and the phenol modification reaction, ultimately affecting the structure and performance of the obtained fiber, and further affecting the performance of the fabric.

[0085] Examples 4-6 and Comparative Examples 3-6

[0086] A method for preparing a bast antibacterial fiber, compared with Example 1, the difference is that the volume ratio of alcohol to water in the alcohol / water system in step S2 is different, and the others are substantially the same as Example 1, which will not be repeated here.

[0087] The hemp bast antibacterial fibers and fabrics prepared in Examples 4-6 and Comparative Examples 3-6 were tested for performance, and the results are shown in Table 2.

[0088] Table 2 Performance of hemp bast antibacterial fibers and fabrics prepared in Examples 4-6 and Comparative Examples 3-6

[0089]

[0090] As can be seen from Table 2, as the alcohol content of the alcohol / water system gradually increases, the antibacterial rate and strength of the obtained hemp bast antibacterial fibers and the air permeability of the fabrics generally show a trend of first increasing and then decreasing, and the bending stiffness of the fabrics shows a trend of first decreasing and then increasing. When the volume ratio of alcohol / water is 30%:70%, the comprehensive performance of the obtained fibers and fabrics is the best. This is likely because when the volume ratio of alcohol / water is 30%:70%, the micro-nano regulation effect of the alcohol / water system on lignin is the best, and the size and distribution of the lignin adhered to the surface of the cellulose fibers obtained by micro-nano structure lignin are more uniform. The number of hydroxyl groups on the surface of the hemp bast antibacterial fibers obtained after phenolation modification is moderate, and the hydroxyl groups are uniformly distributed, thereby improving the performance of the fibers.

[0091] Examples 7-8 and Comparative Examples 7-8

[0092] A method for preparing a bast antibacterial fiber, which is different from Example 1 in that the concentration of the lithium bromide solution in step S3 is different, and other aspects are substantially the same as those of Example 1, which will not be repeated here.

[0093] The hemp bast antibacterial fibers and fabrics prepared in Examples 7-8 and Comparative Examples 7-8 were tested for performance, and the results are shown in Table 3.

[0094] Table 3 Performance of hemp bast antibacterial fibers and fabrics prepared in Examples 7-8 and Comparative Examples 7-8

[0095]

[0096]

[0097] As can be seen from Table 3, as the concentration of the lithium bromide solution increases, the antibacterial rate and strength of the obtained hemp bast antibacterial fibers and the air permeability of the fabrics first increase and then decrease, and the bending stiffness generally shows a trend of first decreasing and then increasing. When the concentration of the lithium bromide solution is 50%, the comprehensive performance of the obtained fibers is the best. This is likely because when the concentration of the lithium bromide solution is too low, the phenolation modification reaction is not sufficient, and when the concentration of the lithium bromide solution is too high, the high concentration makes the phenolation modification reaction too intense, thereby affecting the distribution of the hydroxyl groups on the surface of the obtained antibacterial fibers, and further affecting the performance of the fibers and fabrics.

[0098] Example 9 and Comparative Examples 9-10

[0099] A bast antibacterial fiber preparation method, compared with example 1, the difference is that the reaction temperature in step S2 is different, and the others are basically the same as example 1, which will not be repeated here.

[0100] The performance of the hemp bast antibacterial fiber and its fabric prepared in example 9 and comparative examples 9-10 was tested, and the results are shown in table 4.

[0101] Table 4 Performance of hemp bast antibacterial fiber and its fabric in example 9 and comparative examples 9-10

[0102]

[0103] From table 4, it can be seen that with the continuous increase of the reaction temperature in step S2, the antibacterial rate and strength of the obtained hemp bast antibacterial fiber, and the air permeability of the fabric first increase and then decrease, and the bending stiffness of the fabric basically presents the trend of first decreasing and then increasing, which may be because the change of the reaction temperature affects the breaking process of the lignin molecular structure, affects the micro-nano regulation process, affects the structure, quantity and distribution of the lignin on the cellulose fiber surface adhered by the micro-nano structure lignin, and further affects the subsequent phenolization modification process, and finally affects the performance of the fiber and the fabric.

[0104] Example 10 and comparative examples 11-12

[0105] A bast antibacterial fiber preparation method, compared with example 1, the difference is that the reaction time in step S2 is different, and the others are basically the same as example 1, which will not be repeated here.

[0106] The performance of the hemp bast antibacterial fiber and its fabric prepared in example 10 and comparative examples 11-12 was tested, and the results are shown in table 5.

[0107] Table 5 Performance of hemp bast antibacterial fiber and its fabric in example 10 and comparative examples 11-12

[0108]

[0109] From table 5, it can be seen that when the reaction time is 45 min, the comprehensive performance of the prepared fiber and fabric is the best, and too long or too short reaction time will affect its performance.

[0110] Example 11

[0111] A bast antibacterial fiber preparation method, compared with example 1, the difference lies in that the bast fiber selected in step S1 is jute bast fiber, and the others are basically the same as example 1, which will not be repeated here. The antibacterial rate of the obtained jute bast antibacterial fiber against staphylococcus aureus is 96.77%, the antibacterial rate against escherichia coli is 96.67%, the strength is 30.2 cN / tex, the air permeability of the fiber fabric is 788 mm / s, and the bending stiffness is 2.05 cN·cm 2 The overall performance of the obtained jute bast antibacterial fiber is good, which shows that different types of hemp fibers treated by the method of the application can achieve good results

[0112] Comparative example 13

[0113] A bast antibacterial fiber preparation method, compared with example 1, the difference lies in that step S2 is not performed, that is, no alcohol / water system treatment is performed, and the others are basically the same as example 1, which will not be repeated here.

[0114] Comparative example 14

[0115] A bast antibacterial fiber preparation method, compared with example 1, the difference lies in that step S3 is not performed, that is, no phenol modification reaction is performed, and the others are basically the same as example 1, which will not be repeated here.

[0116] Comparative example 15

[0117] A bast antibacterial fiber preparation method, comprising the following steps:

[0118] S1, 2.0g of the same Hanma bast fiber as in example 1 is reacted in 120mL of 20% sodium hydroxide solution with a bath ratio of 1:60, the reaction temperature is 100℃, and the reaction time is 6h, the lignin on the surface of the bast antibacterial fiber is completely removed, after the reaction is completed, the fiber is taken out, washed several times with distilled water, the impurities on the surface of the fiber are removed by using a small air flow impurity removal machine, and the fiber is dried to constant weight in a constant temperature drying box at 40℃. Alkalized cellulose fiber with substantially no lignin on the surface is obtained.

[0119] S2, after the lignin is dissolved in deionized water, hydrochloric acid is used to adjust the pH to 2 for acid precipitation, and after washing to pH 3-4, an organic solvent or mixed solvent is added for room temperature stirring treatment, and the lignin is obtained by filtration and drying. Fractionated lignin; then the lignin is dissolved in an organic solvent system, and finally dried by rotary evaporation to obtain lignin with micro-nano structure with a size of 200-300nm by anti-solvent precipitation method (uniformly adding distilled water or reverse operation to the dissolution solution).

[0120] S3, the lignin with micro-nano structure of 200-300 nm prepared in step S2 is dispersed in the mixed solution of ethanol / water to prepare a lignin ethanol solution with a lignin mass concentration of 9%, and the volume ratio of ethanol to water in the ethanol / water system is 30%:70%.

[0121] S4, 1.5 g of the alkali cellulose fiber prepared in step S1 is weighed and added into 120 mL of the lignin ethanol solution to prepare a blending suspension of lignin nanoparticles / fiber; 58 mL of a paste cationic starch solution with a concentration of 1 g / L is slowly added into the blending suspension while stirring, at this time, the lignin nanoparticles will be combined with the fiber in situ with the cationic paste starch as a medium, and precipitate; the product is filtered to obtain a lignin-based hemp bast fiber.

[0122] S5, bromic acid is added into the lithium bromide solution, the pH value of the lithium bromide solution is adjusted to 5.4, 1.0 g of the lignin-based hemp bast fiber prepared in step S4 is weighed and soaked in a lithium bromide solution with a mass concentration of 50% at a bath ratio of 1:80, after the fiber is fully swollen, the oil bath is heated to 100°C for 90 min, after the reaction is completed, the fiber and the solution mixture are cooled in ice water, and the fiber is collected by filtering on a glass funnel, washed with deionized water several times, and dried in a constant temperature drying oven at 40°C until the weight is constant to obtain an antibacterial hemp bast fiber.

[0123] Comparative Example 16

[0124] A preparation method of a bast antibacterial fiber, referring to the patent with application number 201810820351.5, comprising the following steps:

[0125] S1, 80 mL of a sodium hydroxide solution with a mass concentration of 10% is prepared, then 4.0 g of the hemp bast fiber used in Example 1 is added, the fiber is fully swollen, soaked at a temperature of 30°C for 120 min, the fiber is taken out, washed with distilled water several times, and dried in a constant temperature drying oven at 40°C until the weight is constant;

[0126] S2, 3.5 g of the fiber prepared in step S1 is weighed and added into 70 mL of a NaIO4 solution with a concentration of 10 g / L, after the fiber is fully swollen, the reaction is carried out in a constant temperature shaking box at 40°C for 240 min, the fiber is taken out, washed with distilled water several times, and dried in a constant temperature drying oven at 40°C until the weight is constant;

[0127] S3, 3.0 g of the fiber prepared in step S2 is weighed and added into 60 mL of a pure triethylenetetramine solution, the reaction is carried out in a constant temperature shaking box at 60°C for 12 h, the fiber is taken out, washed with distilled water several times, and dried in a constant temperature drying oven at 40°C until the weight is constant;

[0128] S4, 3.0 g of the fiber prepared in step S3 was weighed out and added to 60 mL of a GTA solution with a concentration of 30%, and reacted in a constant-temperature shaking box at 60°C for 30 min. The fiber was taken out, washed with distilled water several times, and dried in a constant-temperature drying box at 40°C until the weight was constant, to obtain the quaternary ammonium salt modified hemp fiber.

[0129] The hemp bast antibacterial fibers and fabrics prepared in Comparative Examples 13-16 were subjected to performance testing, and the results are shown in Table 6.

[0130] Table 6 Performance of hemp bast antibacterial fibers and fabrics prepared in Comparative Examples 13-16

[0131]

[0132] The hemp bast antibacterial fiber prepared in Comparative Example 13 has many blocky lignins attached to the surface of the fiber, and the lignins are not micro-nano-structured in situ, so the overall performance of the obtained hemp bast antibacterial fiber is poor.

[0133] The data of Comparative Example 14 and Example 1 further illustrate that the phenolation modification increases the number of phenolic hydroxyl groups in the molecular structure of lignin, thereby improving the antibacterial performance. That is, the bast antibacterial fiber prepared in Example 1 indeed contains a large number of phenolic hydroxyl antibacterial functional groups, and exhibits excellent antibacterial properties. At the same time, as can be seen from the data of Comparative Example 14, the phenolation modification process also affects the strength of the fiber and the air permeability and bending rigidity of the fabric.

[0134] The hemp bast antibacterial fiber prepared in Comparative Example 15 has certain antibacterial properties, but far from meeting the requirements. It can be seen that artificially attaching micro-nano-structured lignin to the surface of the fiber and performing phenolation modification treatment seriously affect the antibacterial properties and strength of the obtained fiber, and at the same time, this method of introducing antibacterial components by post-finishing technology affects the softness and comfort of the fabric.

[0135] The fiber prepared in Comparative Example 16 has good antibacterial properties against Micrococcus and Escherichia coli, but the additional introduction of quaternary ammonium salt antibacterial components affects the performance of the fiber, and reduces the strength, air permeability and softness of the fiber.

[0136] The bast antibacterial fibers prepared in Example 1, 11 and Comparative Examples 13-16 were subjected to washing resistance performance testing. The testing conditions were: after washing in a commercially available conventional household laundry detergent with a mass concentration of 0.1% at room temperature for 10 times, 30 times and 50 times, drying, and then performing antibacterial testing. The results are shown in Table 7.

[0137] Table 7 Washing resistance performance testing

[0138]

[0139] As shown in Table 7, the phloem antibacterial fiber prepared in Examples 1 and 11 still has an antibacterial rate of more than 90% against Micrococcus and Escherichia coli after 50 times of washing, which shows that the fiber is harmless to human body and has a long-lasting antibacterial effect and stable performance, i.e., the phloem antibacterial fiber prepared in this application has excellent, rapid and long-acting antibacterial properties, and is very suitable for the production of various antibacterial textiles. The fibers obtained in Comparative Examples 13-16 have a significantly decreased antibacterial performance after multiple washes, and do not have a long-lasting antibacterial property.

[0140] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing bast antibacterial fiber, characterized in that: The steps include: S1, reacting bast fiber in an alkali solution with a mass concentration of 20%-30% at a bath ratio of 1:(30-100) to obtain alkalized cellulose fiber; S2. Immersing the alkalized cellulose fiber in an alcohol / water system at a bath ratio of 1:(30-100) for reaction at a temperature of 50-150° C. for 30-60 min to obtain cellulose fiber with micro-nanostructured lignin adhered thereto; wherein the volume ratio of alcohol to water in the alcohol / water system is 20%-80%:80%-20%; S3. Immerse the cellulose fiber adhered with the micro-nanostructured lignin in a metal bromide solution with a mass concentration of 40%-60% at a bath ratio of 1:(20-100) under acidic conditions to react and obtain bast antibacterial fiber.

2. The method for preparing the antibacterial bast fiber according to claim 1, characterized in that: In the cellulose fibers to which the micro-nanostructured lignin is adhered in step S2, the mass concentration of lignin is 5%-15%.

3. The method for preparing bast antibacterial fiber according to claim 1, characterized in that: In step S3, the cellulose fibers adhered with the micro-nanostructured lignin are immersed in a metal bromide solution having a mass concentration of 40%-60% at a bath ratio of 1:(20-100) for reaction at a reaction temperature of 100-120° C. and a reaction time of 60-120 min.

4. The method for preparing the antibacterial bast fiber according to claim 3, characterized in that: The pH value of the acidic condition is 4.5-7.

2.

5. The method for preparing bast antibacterial fiber according to claim 1, characterized in that: In step S1, the bast fiber is reacted in an alkaline solution with a mass concentration of 20%-30% at a bath ratio of 1:(30-100), the reaction temperature is 80-100° C., and the reaction time is 1-5 hours.

6. The method for preparing bast antibacterial fiber according to claim 1, characterized in that: The bast fiber includes one or more of ramie fiber, flax fiber, jute fiber, hemp fiber, apocynum venetum fiber and banana fiber.

7. A bast antibacterial fiber, characterized in that: The antibacterial bast fiber is prepared by the preparation method of any one of claims 1 to 6.

8. The antibacterial bast fiber according to claim 7, characterized in that: The antibacterial rate of the bast antibacterial fiber against Staphylococcus aureus is as high as 97.73%, and the antibacterial rate after washing 50 times is as high as 91.44%; the antibacterial rate against Escherichia coli is as high as 98.70%, and the antibacterial rate after washing 50 times is as high as 92.65%; the strength is as high as 34.2 cN / tex, the air permeability of the fiber fabric is as high as 847 mm / s, and the bending stiffness is only 1.85 cN·cm².

9. Use of the bast antibacterial fiber prepared by the preparation method of the bast antibacterial fiber according to any one of claims 1 to 6 or the bast antibacterial fiber according to any one of claims 7 to 8 in antibacterial functional textiles.

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