Fiber surface modification method

Abstract

The invention discloses a fiber surface modification method which comprises the following steps: adjusting the pH value of deionized water to 3.0-4.0 by using a buffer solution, and then adding a surfactant and protease with the concentration of the protease in the system being 0.02-2.0 g / mL; and modifying the fabric, and then washing and drying the fabric. According to the method for modifying the surface of the fiber, the pH value of the system is controlled to be 3.0-4.0 all the time, and the nonionic surfactant is added, so that the protease efficiently plays a role to modify the fiber, and a synergistic interaction effect is generated; meanwhile, a microcosmic rough structure is formed on the surface of the fiber through denudation, and the durability of the finishing effect is improved through the dual effects of mechanical anchoring and valence bond combination; a mixture of anionic sodium dodecyl benzene sulfonate and nonionic twin-80 is adopted as a surfactant, the strength of sodium dodecyl benzene sulfonate micelles is enhanced, meanwhile, the viscosity of the hydrosol can be effectively reduced, and then the stability of the hydrosol and the uniformity of the particle size are improved.

Description

[0001] This application is a divisional application of the invention patent application with the application date of October 29, 2021, the application number of 2021112726387, and the invention name of "A Fabric and Its Preparation Method". Technical Field

[0002] The present invention relates to the technical field of textiles, and specifically relates to a method for surface modification and modification of fibers. Background Art

[0003] With the development of technology and the improvement of living standards, people are increasingly pursuing an environmentally friendly, healthy and safe life, and functional textiles have gradually become the trend of today's textile development. Functional textiles refer to textiles with some special functions different from the inherent properties of ordinary textiles. According to different properties and uses, functional textiles can be mainly divided into health and environmental protection functions, protective functions, medical and health care functions, thermal and moisture comfort functions, etc.

[0004] The sol-gel technology refers to a method of generating functional films with different components on the surface of a substrate through solutions, sol-gels and heat treatments of compounds containing highly active chemical components, so as to improve various functional characteristics of textiles such as physical and mechanical properties (such as abrasion resistance), antistatic properties, anti-adhesion properties, and flame retardancy. Among them, polyalkylsiloxane hydrosol refers to a reactive functional material formed by the hydrolysis and condensation reactions of alkylsiloxanes, and can generate functional films on the fiber surface through valence bond binding and silicon hydroxyl groups (Si-OH), thereby endowing textiles with functional characteristics.

[0005] When using polyalkylsiloxane to modify polyamide fibers, not only the amount of polyalkylsiloxane fixed is reduced due to the surface hydrophobicity of the fibers, but also the durability of the modification effect is affected due to the small number of active reaction groups on the fiber surface. Theoretical analysis shows that one of the effective methods to improve the modification effect of polyalkylsiloxane is to construct a rough structure and generate active reactive groups on the surface of polyamide fibers through modification.

[0006] At present, the main methods for surface modification of polyamide fibers are concentrated acid or concentrated alkali hydrolysis methods (such as the relevant contents disclosed in patents with application numbers 201010218397.3, 202010654281.8, 202010654275.2, etc.), plasma methods and electron beam irradiation methods. Among them, the acid or alkali hydrolysis method often causes serious damage to the fiber strength due to difficult control of processing conditions, and the plasma method and electron beam radiation method have not been well realized in large-scale production applications at present.

[0007] Bioenzymes are widely used in textile finishing due to their high efficiency, specificity, and mild treatment conditions. Literature reports that proteases, cutinases, amidases, and lipases can hydrolyze the amide bonds (-COONH-) in polyamides, but the catalytic activity of enzymes towards polyamide polymers is not high, the treatment time is too long, and the improvement of related properties such as the hydrophilicity and dyeability of modified fibers is not satisfactory. In addition, due to surface erosion, bioenzyme treatment will also cause certain damage to fiber strength.

[0008] For example, in a Chinese invention patent application with the application number 200580018511.5 and the title of "Method for Modifying Polyamide", a method of applying protease to the modification of polyamide is disclosed. However, the content disclosed in the application mainly includes increasing the content of carboxyl groups (-COOH) on the surface of polyamide fibers through protease modification, thereby improving the hydrophilicity and dyeability of the fibers; and in the treatment method disclosed in the application, only salts (sodium phosphate and sodium citrate) are used to adjust the pH value of the enzyme reaction solution, and no other additives are added. The disadvantage is that the hydrolysis rate of amide bonds is slow. To obtain a sample with a significantly increased carboxyl content, it often takes 24 hours or longer to react. Summary of the Invention

[0009] In view of this, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a method for preparing a fabric that can more persistently and effectively maintain its characteristics.

[0010] To achieve the above purpose, the present invention adopts the following technical solutions:

[0011] A method for preparing a fabric, comprising the following steps: surface-modifying the fibers of the fabric with protease under acidic conditions; then preparing a polyalkylsiloxane hydrosol; finishing the modified fabric with the prepared polyalkylsiloxane hydrosol to obtain the fabric; the surfactant used in the process of preparing the polyalkylsiloxane hydrosol is a mixture composed of sodium dodecylbenzenesulfonate and twain-80. The fibers used in the fabric are aliphatic polyamide fibers.

[0012] According to some preferred embodiments of the present invention, the acidic condition is a pH value of 3.0 - 4.0, preferably 3.5.

[0013] According to some preferred embodiments of the present invention, a surfactant is used in the process of modifying the fibers of the fabric. The surfactant is a non-ionic surfactant, preferably nonylphenol polyoxyethylene ether and aliphatic polyoxyethylene ether surfactants.

[0014] According to some preferred embodiments of the present invention, a buffer solution is used in the process of modifying the fibers of the fabric. The buffer solution is a mixture composed of 0.1 - 0.3 mol / L of disodium hydrogen phosphate and 0.05 - 0.2 mol / L of citric acid. Preferably, the buffer solution is a mixture composed of 0.2 mol / L of disodium hydrogen phosphate and 0.1 mol / L of citric acid in a volume ratio of 3:7, so as to maintain the pH value of the system at about 3.5.

[0015] The principle of surface modification of fibers is as follows: When modifying the fiber surface, carboxyl groups (-COOH) that can react with the silanol groups (-Si-OH) on the surface of silica sol particles are generated through the hydrolysis of amide bonds (-COONH-), and at the same time, a microscopic rough structure is formed on the fiber surface through erosion. The durability of the finishing effect is improved through the dual actions of mechanical nail anchoring and valence bond binding; the optimal application pH value for acid protease to modify the surface of polyamide fibers is about 3.5. Both acidity and protease can produce a synergistic effect during the process of hydrolyzing the amide bond (-COONH-) in the molecular structure of polyamide fibers to generate amino groups (-NH 2 ) and carboxyl groups (-COOH); adjusting the pH with a buffer solution can effectively neutralize the carboxyl groups (-COOH) generated during the modification process, so that the pH value of the system is always maintained at about 3.5 to ensure the highest efficiency of the protease; the hydrolysis of amide bonds by organic acids is milder than that of inorganic strong acids, and the conditions are easy to control; adding a non-ionic surfactant can improve the wettability of the fiber surface, accelerate fiber swelling, and then improve the spreading of the bio-enzyme treatment solution on the fiber surface, and improve the modification efficiency by increasing the effective contact area between the bio-enzyme and the fiber surface.

[0016] According to some preferred embodiments of the present invention, the pH value of deionized water is adjusted to 3.0 - 4.0 with a buffer solution, and then a surfactant and protease are added. The dosage of the surfactant is 1 - 1.5 times the critical micelle concentration (CMC), and the concentration of protease in the system is 0.02 - 2.0 g / mL; the fabric is treated under the condition of a bath ratio of 1:10 - 35, and then the fabric is washed and dried.

[0017] The non-ionic surfactant added in the present invention when protease modifies polyamide fibers can not only improve the wettability of the fiber, enhance the swelling performance of the fiber, increase the effective contact area between the protease and the fiber surface, and improve the treatment efficiency. At the same time, the main purpose of the present invention is to generate more carboxyl groups on the fiber surface through protease modification and form a microscopic rough structure. When finishing with a silica sol-based antibacterial agent, the dual actions of valence bond binding and mechanical nail anchoring are combined to improve the fixing strength of the finishing agent on the fiber surface.

[0018] In some embodiments of the present invention, the specific steps for surface modification of fibers are as follows: Adjust the pH value of 1 L of deionized water to 3.5 with 20 mL of buffer solution, then add a surfactant and 0.2 - 2.0 g of protease. The dosage of the surfactant is 1 - 1.5 times that of CMC. Treat the fabric at 40 °C for 2 - 6 h with a bath ratio of 1∶30. After treatment, inactivate at 60 °C for 10 min, take out the fabric, wash it with water and then dry it.

[0019] According to some preferred implementation aspects of the present invention, the protease is papain. The optimal application pH value of papain is 3.0 - 4.0. The acidity of this pH value will not have an obvious impact on fiber damage and can also produce a synergistic effect with the action of the biological enzyme.

[0020] According to some preferred implementation aspects of the present invention, the surfactant is a mixture composed of sodium dodecylbenzenesulfonate and twain - 80 with a mass ratio of 1∶0.1 - 0.3.

[0021] According to some preferred implementation aspects of the present invention, the preparation of the polyalkylsiloxane hydrosol includes the following steps: Add hydrochloric acid to deionized water, then add a surfactant and an antifoaming agent, stir to fully dissolve and mix the surfactant, add alkylsiloxane while stirring. After the alkylsiloxane is added, continue to stir and heat up to 40 - 60 °C, and react for 30 - 60 min under stirring conditions to obtain the polyalkylsiloxane hydrosol.

[0022] In some embodiments of the present invention, the specific steps for the preparation of the polyalkylsiloxane hydrosol are as follows: Under the condition of 25 - 30 °C, add 3 - 6 mL of hydrochloric acid to 1 L of deionized water, then add 1 - 2 g of surfactant and 0.1 - 0.3 g of antifoaming agent, stir at a speed of 300 r / min to fully dissolve sodium dodecylbenzenesulfonate, adjust the stirring speed to 600 - 1000 r / min, and add 20 - 40 g of alkylsiloxane while stirring within 5 - 10 min. After the alkylsiloxane is added, continue to stir for 60 - 90 min, then heat up at a heating rate of 1 - 2 °C / min to 40 - 60 °C, and react for 30 - 60 min under stirring conditions to obtain the polyalkylsiloxane hydrosol.

[0023] The principle of this step is as follows: Use a mixture of an anionic surfactant sodium dodecylbenzenesulfonate and a non - ionic surfactant twain - 80 as the surfactant. The reason is that the addition of twain - 80 will not change the charge amount of the hydrosol system, but can enhance the strength of the sodium dodecylbenzenesulfonate micelles, and at the same time can effectively reduce the viscosity of the hydrosol, thereby improving the stability of the hydrosol and the uniformity of the particle size; the addition of the antifoaming agent can effectively avoid the generation of foam by the surfactant under high - speed stirring conditions, thereby avoiding affecting the dispersibility of the alkylsiloxane and affecting the final effect.

[0024] The preferred alkylsiloxane is selected from one or more of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, γ-aminopropyltriethoxysilane.

[0025] According to some preferred implementation aspects of the present invention, an antibacterial agent is further added during the preparation process of the polyalkylsiloxane hydrosol, and the antibacterial agent is a chitosan / micron silver composite antibacterial agent.

[0026] In some embodiments of the present invention, the preparation method of the hydrosol with antibacterial function is as follows: Add a surfactant with a mass concentration of 0.1% and an antifoaming agent with a mass concentration of 0.01% to a hydrochloric acid deionized aqueous solution with a mass concentration of 0.46%, stir at a speed of 300 r / min at a temperature of 25 °C for 60 min. After the sodium dodecylbenzenesulfonate is fully dissolved, add a chitosan / micron silver composite antibacterial agent with a mass ratio of 15% to the alkylsiloxane, and continue to stir for 60 min to disperse the antibacterial agent evenly. Add an alkylsiloxane with a mass concentration of 4% within 5 min under the stirring condition of 600 r / min. After the alkylsiloxane is added, continue to stir for 60 min, then heat up to 60 °C at a heating rate of 2 °C / min, and react for 30 min under stirring to obtain SiO 2 Hydrosol-based chitosan / micron silver composite antibacterial agent. The mass concentration in the present invention is the mass concentration of the corresponding substance in the formed solution, rather than the original concentration of the added substance.

[0027] In some embodiments of the present invention, the preparation of the chitosan / micron silver composite antibacterial agent includes the following steps:

[0028] 1) Prepare a chitosan solution: Add chitosan with a mass concentration of 2-5% and acetic acid with a mass concentration of 1.0-2.0% to 200 mL of deionized water. The deacetylation degree of the chitosan used is ≥90%.

[0029] 2) Prepare a micron silver dispersion: Add 0.1-0.2% of sodium dodecylbenzenesulfonate and 2-5 mL of ethanol to 50 mL of deionized water, stir at a speed of 300 r / min. After the sodium dodecylbenzenesulfonate is completely dissolved, add micron silver with a mass of 5-10% of the chitosan while stirring.

[0030] 3) Preparation of composite antibacterial agent: at 25-30°C, stir at a speed of 600r / min, slowly add the micron elemental silver dispersion into the chitosan solution within 10-20min, after the addition is complete, continue stirring for 120-240min, use a centrifuge to precipitate the crude chitosan / micron elemental silver composite antibacterial agent, then wash with deionized water for 3-5 times, and filter to obtain the chitosan / micron elemental silver composite antibacterial agent.

[0031] In some embodiments of the present invention, the preparation of micron elemental silver comprises the following steps: adding polyvinyl pyrrolidone with a mass concentration of 0.5-1.0% and a reducing agent with a mass concentration of 1-2% to 200 mL of deionized water at 25-30°C, stirring at a speed of 300 r / min, and after the polyvinyl pyrrolidone and the reducing agent are completely dissolved, adjusting the pH of the reaction solution to 3-4 with an acetic acid-sodium acetate buffer solution, slowly adding silver nitrate with a mass concentration of 2-5% within 5-10 minutes under stirring, continuing to stir for 10-20 minutes after the addition, and then heating to 40-50°C at a speed of 1-2°C / min, reacting at a constant temperature for 30-60 minutes, precipitating the micron elemental silver crude product with a centrifuge, and then washing with deionized water 3-5 times, and filtering to obtain micron elemental silver with a particle size of 1-20 μm.

[0032] The reducing agent used in the preparation process of micron elemental silver is one of trisodium citrate and ascorbic acid or a complex of the two.

[0033] According to some preferred embodiments of the present invention, finishing the modified fabric comprises the following steps: adjusting the pH value of the polyalkylsiloxane hydrosol to 6-7 with an alkali agent, finishing the modified fabric by a padding method, and then washing and drying to produce the fabric.

[0034] According to some preferred embodiments of the present invention, the alkali agent refers to a sodium hydroxide solution with a mass concentration of 4-8 g / L.

[0035] In some embodiments of the present invention, the steps of polyalkylsiloxane finishing of modified fabrics are as follows: at 25-30°C, the pH value of the polyalkylsiloxane hydrosol is adjusted to 6-7 with an alkali agent, and the modified polyamide fabric is finished by a two-immersion and two-rolling method with a rolling rate of 60-100%, and then dried at a temperature of 80-90°C for 2-5 minutes, and then baked at a temperature of 140-160°C for 3-6 minutes, washed with water, and finally dried at a temperature of 80-100°C to make a multifunctional polyamide fabric.

[0036] The principle of this step is as follows: Polyamide fibers are prone to hydrolysis under acidic conditions, which will affect the service performance of the fabric. Adjusting the pH value of the silica sol to 6-7 will neither cause the rapid condensation of sol particles nor have an obvious impact on the fiber strength.

[0037] The present invention also provides a fabric prepared by the preparation method described above.

[0038] Due to the above technical solutions, compared with the prior art, the advantages of the present invention are as follows: In the method for surface modification of fibers of the present invention, by controlling the pH value of the system to be always 3.0-4.0 and adding a non-ionic surfactant, protease can efficiently play its role in modifying the fibers, resulting in a synergistic effect; at the same time, a microscopic rough structure is formed on the fiber surface through the erosion effect, and the durability of the finishing effect is improved through the dual effects of mechanical nail anchoring and valence bond binding; a mixture of anionic sodium dodecylbenzenesulfonate and non-ionic twain-80 is used as the surfactant to enhance the strength of the sodium dodecylbenzenesulfonate micelles, and at the same time, the viscosity of the hydrosol can be effectively reduced, thereby improving the stability of the hydrosol and the uniformity of the particle size. Brief Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a micrograph of the original polyamide fiber used in the preferred embodiment of the present invention;

[0041] Figure 2 It is a micrograph of the polyamide fiber after being modified by bio-enzyme in the preferred embodiment 1-1 of the present invention;

[0042] Figure 3 It is a comparison picture of the antibacterial effects of the fabrics prepared in the preferred embodiment 3-1 of the present invention and the comparative examples 1-4 to 1-7. Detailed Embodiments

[0043] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to 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 shall fall within the protection scope of the present invention.

[0044] Example 1-1 Fiber Surface Modification

[0045] Adjust the pH value of 1 L of deionized water to the optimal application value of 3.5 for protease with 20 mL of buffer solution, then add 1.0 g of protease and 1.2 CMC nonylphenol polyoxyethylene ether, and treat at 40 °C for 3 h with a liquor ratio of 1:30. After treatment, inactivate at 60 °C for 10 min, take out the fabric, wash it with water, and dry it.

[0046] Example 1-2 Fiber Surface Modification

[0047] Adjust the pH value of 1 L of deionized water to the optimal application value of 3.5 for protease with 20 mL of buffer solution, then add 1.5 g of protease and 1.2 CMC nonylphenol polyoxyethylene ether, and treat at 40 °C for 2 h with a liquor ratio of 1:35. After treatment, inactivate at 60 °C for 10 min, take out the fabric, wash it with water, and dry it.

[0048] Example 1-3 Fiber Surface Modification

[0049] Adjust the pH value of 1 L of deionized water to the optimal application value of 3.5 for protease with 20 mL of buffer solution, then add 1.0 g of protease and 1.2 CMC nonylphenol polyoxyethylene ether, and treat at 40 °C for 3 h with a liquor ratio of 1:25. After treatment, inactivate at 60 °C for 10 min, take out the fabric, wash it with water, and dry it.

[0050] Example 2-1 Preparation of Hydrogel with Antibacterial Function

[0051] 1. Preparation of Micron Monometallic Silver

[0052] At 25 °C, add polyvinylpyrrolidone with a mass concentration of 0.7% and a reducing agent with a mass concentration of 1% to 200 mL of deionized water, stir at a speed of 300 r / min. After the polyvinylpyrrolidone and the reducing agent are completely dissolved, adjust the pH of the reaction solution to 3-4 with acetic acid-sodium acetate buffer solution. Under stirring conditions, slowly add silver nitrate with a mass concentration of 3% within 8 min. After adding, continue stirring for 15 min, then heat up to 40 °C at a rate of 1.5 °C / min, keep the temperature constant for reaction for 50 min, precipitate the monometallic silver with a centrifuge, and then wash it 5 times with deionized water and filter it by suction to obtain micron monometallic silver.

[0053] 2. Preparation of Chitosan / Micron Monometallic Silver Composite Antibacterial Agent

[0054] Chitosan solution: Add chitosan with a mass concentration of 3% and acetic acid with a mass concentration of 1.0% to 200 mL of deionized water.

[0055] Micron silver nanoparticle dispersion: Add 0.15% surfactant and 3 mL ethanol to 50 mL deionized water, stir at a speed of 300 r / min. After the sodium dodecyl benzene sulfonate is completely dissolved, add micron silver nanoparticles with a mass of 6% of the chitosan while stirring.

[0056] Under the condition of 25 °C, stir at a speed of 600 r / min, slowly add the micron silver nanoparticle dispersion to the chitosan solution within 10 min. After adding, continue to stir for 150 min, precipitate the silver nanoparticles with a centrifuge, wash with deionized water 5 times, and obtain the chitosan / micron silver nanoparticle composite antibacterial agent by suction filtration.

[0057] 3. SiO 2 Preparation of silica sol-based antibacterial agent

[0058] Add a surfactant with a mass concentration of 0.1% and an antifoaming agent with a mass concentration of 0.01% to a hydrochloric acid deionized water solution with a mass concentration of 0.46%. Stir at a speed of 300 r / min at a temperature of 25 °C for 60 min. After the sodium dodecyl benzene sulfonate is fully dissolved, add the chitosan / micron silver nanoparticle composite antibacterial agent with a mass ratio of 15% to the alkylsiloxane, continue to stir for 60 min to disperse the antibacterial agent evenly, add methyltrimethoxysilane with a mass concentration of 4% within 5 min under the stirring condition of 600 r / min. After adding the precursor, continue to stir for 60 min, then heat up to 60 °C at a heating rate of 2 °C / min, and react for 30 min under stirring to obtain SiO 2 Silica sol-based antibacterial agent. The surfactant is a mixture of sodium dodecyl benzene sulfonate and twain-80 with a mass ratio of 1:0.2.

[0059] Preparation of the antibacterial silica sol in Example 2-2

[0060] 1. Preparation of micron silver nanoparticles

[0061] Under the condition of 25 °C, add polyvinylpyrrolidone with a mass concentration of 0.5% and a reducing agent with a mass concentration of 1.5% to 200 mL deionized water, stir at a speed of 300 r / min. After the polyvinylpyrrolidone and the reducing agent are completely dissolved, adjust the pH of the reaction solution to 3-4 with an acetic acid-sodium acetate buffer solution. Under the stirring condition, slowly add silver nitrate with a mass concentration of 5% within 8 min. After adding, continue to stir for 15 min, then heat up to 40 °C at a rate of 1.5 °C / min, keep the temperature constant for 30 min, precipitate the silver nanoparticles with a centrifuge, wash with deionized water 5 times, and obtain micron silver nanoparticles by suction filtration.

[0062] 2. Preparation of chitosan / micron silver nanoparticle composite antibacterial agent

[0063] Chitosan solution: Add chitosan with a mass concentration of 3% and acetic acid with a mass concentration of 1.0% to 200 mL of deionized water for dissolution.

[0064] Micron silver dispersion: Add 0.15% surfactant and 3 mL of ethanol to 50 mL of deionized water, stir at a speed of 300 r / min. After sodium dodecylbenzenesulfonate is completely dissolved, add micron silver with a mass 10% of that of chitosan while stirring.

[0065] Under the condition of 25 °C, stir at a speed of 600 r / min, slowly add the micron silver dispersion to the chitosan solution within 10 min. After adding, continue to stir for 200 min, precipitate the silver by centrifugation, wash it 5 times with deionized water, and obtain the chitosan / micron silver composite antibacterial agent by suction filtration.

[0066] 3. SiO 2 Preparation of hydrogel-based antibacterial agent

[0067] Add a surfactant with a mass concentration of 0.16% and an antifoaming agent with a mass concentration of 0.016% to a 0.5% hydrochloric acid deionized aqueous solution. Under the condition of a temperature of 25 °C, stir at a speed of 300 r / min for 60 min. After sodium dodecylbenzenesulfonate is fully dissolved, add the chitosan / micron silver composite antibacterial agent with a mass ratio of 20% to alkylsiloxane, and continue to stir for 90 min to disperse the antibacterial agent evenly. Add propyltrimethoxysilane with a mass concentration of 4% within 5 min under the stirring condition of 600 r / min. After adding the precursor, continue to stir for 60 min, then heat up to 40 °C at a heating rate of 1.5 °C / min, and react for 30 min under stirring conditions to obtain SiO 2 Hydrogel-based antibacterial agent. The surfactant is a mixture composed of sodium dodecylbenzenesulfonate and twain-80 with a mass ratio of 1:0.3.

[0068] Preparation of hydrogel with antibacterial function in Example 2 - 3

[0069] 1. Preparation of micron silver

[0070] At 25 °C, 0.7% by mass of polyvinylpyrrolidone and 1% by mass of a reducing agent were added to 200 mL of deionized water, and the mixture was stirred at a speed of 300 r / min. After the polyvinylpyrrolidone and the reducing agent were completely dissolved, the pH of the reaction solution was adjusted to 3 - 4 with an acetic acid - sodium acetate buffer solution. Under stirring conditions, 4% by mass of silver nitrate was slowly added within 10 min. After addition, stirring was continued for 15 min, and then the temperature was raised to 40 °C at a rate of 1.5 °C / min and the reaction was carried out at a constant temperature for 40 min. The silver metal was precipitated by a centrifuge, washed 5 times with deionized water, and the silver metal in micrometer size was obtained by suction filtration.

[0071] 2. Preparation of chitosan / silver metal in micrometer size composite antibacterial agent

[0072] Chitosan solution: 3% by mass of chitosan and 1.0% by mass of acetic acid were added to 200 mL of deionized water.

[0073] Silver metal in micrometer size dispersion: 0.1% by mass of a surfactant and 3 mL of ethanol were added to 50 mL of deionized water, and the mixture was stirred at a speed of 300 r / min. After sodium dodecylbenzenesulfonate was completely dissolved, silver metal in micrometer size with a mass 8% of that of chitosan was added while stirring.

[0074] At 25 °C, the mixture was stirred at a speed of 600 r / min, and the silver metal in micrometer size dispersion was slowly added to the chitosan solution within 10 min. After addition, stirring was continued for 150 min. The silver metal was precipitated by a centrifuge, washed 5 times with deionized water, and the chitosan / silver metal in micrometer size composite antibacterial agent was obtained by suction filtration.

[0075] 3. SiO 2 Preparation of SiO

[0076] 0.13% by mass of a surfactant and 0.013% by mass of an antifoaming agent were added to an aqueous solution of 0.46% by mass hydrochloric acid in deionized water. The mixture was stirred at a speed of 300 r / min at 25 °C for 60 min. After sodium dodecylbenzenesulfonate was fully dissolved, a chitosan / silver metal in micrometer size composite antibacterial agent with a mass ratio of 20% to alkylsiloxane was added, and stirring was continued for 60 min to disperse the antibacterial agent evenly. 4% by mass of alkylsiloxane (the mass ratio of methyltrimethoxysilane to propyltrimethoxysilane was 3:1) was added within 5 min under stirring at 600 r / min. After the precursor was added, stirring was continued for 60 min, and then the temperature was raised to 40 °C at a rate of 2 °C / min and the reaction was carried out under stirring for 40 min to obtain SiO 2 aqueous sol - based antibacterial agent. The surfactant was a mixture of sodium dodecylbenzenesulfonate and twain - 80 with a mass ratio of 1:0.1.

[0077] Examples 2-1 to 2-3 provide a preparation method of a multifunctional composite antibacterial finishing agent, which has the following advantages: simple process, stable and easy-to-control process parameters; excellent antibacterial effect of the antibacterial finishing agent; active groups capable of forming valence bonds with the fiber surface, and the antibacterial effect of the finished fabric is lasting; the finishing agent can endow the finished fabric with good antibacterial and bacteriostatic properties, water repellency and soft handfeel at the same time.

[0078] Preparation of the fabric in Example 3-1

[0079] The preparation method of the multifunctional fabric in this example specifically includes the following steps:

[0080] (1) Fiber surface modification treatment: Modify the polyamide fabric by using the fiber surface modification method in Example 1-1;

[0081] (2) Preparation of the composite antibacterial finishing agent: Prepare the SiO 2 hydrosol-based chitosan / micron silver composite antibacterial agent by using the preparation method in Example 2-1.

[0082] (3) Polyalkylsiloxane finishing of the modified fabric: Under the condition of 25°C, adjust the pH value of the polyalkylsiloxane hydrosol-based antibacterial agent in step (2) to 6-7 with an alkali agent, and use the two-dip and two-roll method to finish the modified polyamide fabric in step (1), with a liquor pickup rate of 80%, then dry it at 80°C for 2 min, then cure it at 140°C for 3 min, wash it with water, and finally dry it at 80°C to make a multifunctional polyamide fabric.

[0083] Preparation of the fabric in Example 3-2

[0084] The preparation method of the multifunctional fabric in this example specifically includes the following steps:

[0085] (1) Fiber surface modification treatment: Modify the polyamide fabric by using the fiber surface modification method in Example 1-2;

[0086] (2) Preparation of the composite antibacterial finishing agent: Prepare the SiO 2 hydrosol-based chitosan / micron silver composite antibacterial agent by using the preparation method in Example 2-2.

[0087] (3) Modification of the fabric with polyalkylsiloxane: Under the condition of 25°C, use an alkaline agent to adjust the pH value of the polyalkylsiloxane hydrosol-based antibacterial agent in step (2) to 6 - 7. Use the two-dip two-roll method to finish the modified polyamide fabric in step (1), with a liquor pickup rate of 80%. Then dry it at 80°C for 2 minutes, cure it at 140°C for 3 minutes, wash it with water, and finally dry it at 80°C to make a multifunctional polyamide fabric.

[0088] Preparation of the fabric in Example 3 - 3

[0089] The preparation method of the multifunctional fabric in this example specifically includes the following steps:

[0090] (1) Fiber surface modification treatment: Modify the polyamide fabric using the fiber surface modification method in Example 1 - 3;

[0091] (2) Preparation of the composite antibacterial finishing agent: Prepare the SiO 2 hydrosol-based chitosan / micron silver composite antibacterial agent using the preparation method in Example 2 - 3.

[0092] (3) Modification of the fabric with polyalkylsiloxane: Under the condition of 25°C, use an alkaline agent to adjust the pH value of the polyalkylsiloxane hydrosol-based antibacterial agent in step (2) to 6 - 7. Use the two-dip two-roll method to finish the modified polyamide fabric in step (1), with a liquor pickup rate of 80%. Then dry it at 80°C for 2 minutes, cure it at 140°C for 3 minutes, wash it with water, and finally dry it at 80°C to make a multifunctional polyamide fabric.

[0093] Examples 3 - 1 to 3 - 3 provide a preparation method of a multifunctional polyamide fabric, which has the following advantages: The process is simple, and the process parameters are stable and easy to control; The fabric has excellent hydrophobicity, antistatic property, and a comfortable hand feeling at the same time; The antibacterial functional characteristics of the fabric are persistent, and it has good wash resistance.

[0094] Comparative Example 1 - 1

[0095] The difference between this comparative example and Example 1 - 1 is that: In the fiber surface modification method of this comparative example, when using protease for modification, no non-ionic surfactant is added. The remaining steps of this comparative example are basically the same as those of Example 1 - 1.

[0096] Comparative Example 1 - 2

[0097] The difference between this comparative example and Example 1 - 1 is that: In the fiber surface modification method of this comparative example, the pH value of the system is controlled at 4.2. The remaining steps of this comparative example are basically the same as those of Example 1 - 1.

[0098] Comparative Example 1-3

[0099] The difference between this comparative example and Example 1-1 is that: in the fiber surface modification method of this comparative example, the pH value of the control system is 2.8. The remaining steps of this comparative example are basically the same as those of Example 1-1.

[0100] Comparative Example 1-4

[0101] The difference between this comparative example and Example 3-1 is that: in this comparative example, when preparing the SiO 2 hydrocolloid-based antibacterial agent, micron elemental silver is used to replace the chitosan / micron elemental silver composite antibacterial agent. The remaining steps of this comparative example are basically the same as those of Example 2-1 and Example 3-1.

[0102] Comparative Example 1-5

[0103] The difference between this comparative example and Example 3-1 is that: in this comparative example, when preparing the SiO 2 hydrocolloid-based antibacterial agent, nano elemental silver is used to replace the chitosan / micron elemental silver composite antibacterial agent. The remaining steps of this comparative example are basically the same as those of Example 2-1 and Example 3-1.

[0104] Comparative Example 1-6

[0105] The difference between this comparative example and Example 3-1 is that: in this comparative example, when preparing the SiO 2 hydrocolloid-based antibacterial agent, chitosan is used to replace the chitosan / micron elemental silver composite antibacterial agent. The remaining steps of this comparative example are basically the same as those of Example 2-1 and Example 3-1.

[0106] Comparative Example 1-7

[0107] The difference between this comparative example and Example 3-1 is that: in this comparative example, when preparing the SiO 2 hydrocolloid-based antibacterial agent, chitosan / nano elemental silver composite antibacterial agent is used to replace the chitosan / micron elemental silver composite antibacterial agent. The remaining steps of this comparative example are basically the same as those of Example 2-1 and Example 3-1. Among them, the nano elemental silver is prepared by a conventional method, and then the chitosan / nano elemental silver composite antibacterial agent is prepared by using Step 2 in Example 2-1.

[0108] Comparative Example 1-8

[0109] The difference between this comparative example and Example 3-1 is that: in the fabric preparation method of this comparative example, Step (1) in Example 3-1 is not implemented, that is, the fiber surface is not modified in this comparative example. The remaining steps of this comparative example are basically the same as those of Example 3-1.

[0110] Results and Discussion

[0111] (1) Test on the effect of fiber surface modification

[0112] For the fiber-modified fabrics prepared in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3, the following terminal carboxyl content and weight loss rate were measured. Among them, the test method for the terminal carboxyl content was carried out according to the method described on page 13 of the patent specification with the application number 200580018511.5 and the title of "Method for Modifying Polyamide"; the weight loss rate test was carried out by the constant-temperature dry weight method. The specific method was as follows: The fabric was placed in an oven at 105-110 °C and dried to a constant weight balance (about 4 h), and then weighed with an analytical balance. The weight loss rate = (W 0 -W 1 ) / W 0 ×100%, where: W 0 is the weight of the fabric before treatment; W 1 is the weight of the fabric after treatment. The test results of the modification effect are shown in Table 1 below:

[0113] Table 1 Test results of fiber surface modification effect

[0114] Terminal carboxyl content (mmol / kg) Weight loss rate / % Example 1-1 95.2 1.2±0.3 Example 1-2 101.1 1.3±0.3 Example 1-3 97.2 1.2±0.3 Comparative Example 1-1 88.6 1.1±0.3 Comparative Example 1-2 83.5 0.8±0.3 Comparative Example 1-3 84.3 2.0±0.3

[0115] The test results in Table 1 show that the terminal carboxyl content of the fibers treated in the examples is significantly higher than that of the fibers treated in the comparative examples. The terminal carboxyl content of the fibers treated in Example 1-1 is higher than that of the fibers treated in Comparative Example 1-1, indicating that the addition of the non-ionic surfactant increases the hydrolysis rate of the amide bond. The terminal carboxyl content of the fibers treated in Example 1-2 is the highest because the mass concentration of the protease in Example 1-2 is high, and the effective contact opportunity between the fiber and the bio-enzyme per unit time is more.

[0116] The terminal carboxyl content of the fibers treated in Comparative Example 1-1 is higher than that of the fibers treated in Comparative Examples 1-2 and 1-3. This may be because the pH value of the treatment solution in Comparative Example 1-1 is within the optimal active pH value range of papain, so the terminal carboxyl content of the fibers treated in Comparative Example 1-1 is the highest among the fibers treated in the comparative examples. In addition, compared with Comparative Examples 1-2 and 1-3, the terminal carboxyl content of the fibers treated in Comparative Example 1-3 is slightly higher, which may be because the pH value of the treatment solution in Comparative Example 1-3 is lower (pH = 2.8). The stronger the acidity, the worse the stability of the amide bond. The weight loss rate of the fibers treated in the comparative examples shows that the weight loss of the fibers is caused by the combined action of acidity and protease. The terminal carboxyl content of the fibers treated in Comparative Example 1-1 is the largest, but the weight loss rate is not the largest, indicating that the hydrolysis of the amide bond by protease is milder than that under acidic conditions and will not cause the polyamide molecular chain to break into small molecules and detach from the fiber main body in a short time.

[0117] (2) Antibacterial rate test

[0118] AsFigure 3 As shown, the antibacterial rates of the fabrics prepared in Examples 3-1 to 3-3 and Comparative Examples 1-4 to 1-7 were tested; the test method for the antibacterial rate referred to GB / T 20944.1-2007 Evaluation of antibacterial properties of textiles - Part 1: Agar plate diffusion method. The test results of the antibacterial rate are shown in Table 2 below:

[0119] Table 2 Test results of antibacterial rate

[0120]

[0121] The test results in Table 2 show that when the alkyl polysiloxane hydrosol is used as the matrix, the antibacterial property of chitosan is the worst (Comparative Example 1-6), and the antibacterial properties of micron silver (Comparative Example 1-4) and nano silver (Comparative Example 1-5) both reach 100%. Silver can significantly improve the antibacterial property of chitosan. The antibacterial properties of chitosan / micron silver (Examples 3-1, 3-2, and 3-3) are similar to those of silver (Comparative Examples 1-4 and 1-5), and are better than those of chitosan / nano silver (Comparative Example 1-7). Reason analysis: Chitosan is a porous material. When silver is compounded with chitosan, part of the silver is adsorbed on the surface of chitosan, and the other part is adsorbed into the pores of chitosan. The smaller the particle size of silver, the greater the probability of adsorption into the pores of chitosan. And silver is a contact-type antibacterial agent, so the antibacterial property of chitosan / micron silver (Examples) is better than that of chitosan / nano silver (Comparative Example 1-7).

[0122] (3) Durability test

[0123] The following tests of antibacterial rate, hand feeling, and static contact angle were carried out on the fabrics prepared in Examples 3-1 to 3-3 and Comparative Example 1-8. Among them, the test method for the antibacterial rate referred to GB / T 20944.1-2007 Evaluation of antibacterial properties of textiles - Part 1: Agar plate diffusion method; the hand feeling was tested by the method of touching by hand; the static contact angle was tested using an OCA50Micro type full-automatic single-fiber contact angle measuring instrument (Dataphysics Instruments Co., Ltd., Germany); the washing method referred to GB / T 8629-2017 Textiles - Home laundering and drying procedures for testing. The test results are shown in Table 3 below:

[0124] Table 3 Test results

[0125]

[0126] The test results in Table 3 show that when using the polyalkylsiloxane hydrosol-based antibacterial agent to finish the polyamide fabric, the antibacterial property, hand feeling and static contact angle of the fabrics prepared in Comparative Examples 1-8 (without bioenzyme modification) are similar to those of the fabrics prepared in Examples 3-1 (bioenzyme modification). However, after 20 or 50 washes, the performance of the fabrics prepared in Examples 3-1 is significantly better than that of the fabrics prepared in Comparative Examples 1-8. The main reason is that bioenzyme modification can not only form carboxyl groups (-COOH) that undergo valence bond binding with silanol groups (Si-OH) on the fiber surface, but also form a microscopic rough structure. The rough structure has a mechanical meshing effect with the polyalkylsiloxane coating, thereby improving the durability of the finishing effect.

[0127] Table 3 also shows that changing the polyalkylsiloxane precursor (i.e., the specific substance of alkylsiloxane) can endow the finished fabric with different hand feelings (Examples 3-1, 3-2 and 3-3), but does not affect the antibacterial property (i.e., antibacterial rate) and hydrophobicity (i.e., static contact angle), nor has an obvious impact on the durability of the finishing effect.

[0128] In the preparation method of the present invention, when performing fiber modification, the pH of the system is controlled to be about 3.5. At this time, the acidity has a synergistic effect with the erosion of the polyamide fiber surface by protease. The fiber after erosion can not only effectively increase its adsorption amount of the polyalkylsiloxane hydrosol, but also improve the durability of the effect through mechanical nail anchoring and valence bond binding (-COOH on the fiber and -OH on the polyalkylsiloxane). At the same time, the film formed by the polyalkylsiloxane can make up for the damage to the fiber strength caused by the erosion.

[0129] In the fabric preparation method of the present invention, by controlling the pH value of the system to be always 3.0 - 4.0 and adding a nonionic surfactant, the protease can efficiently play its role in modifying the fiber, resulting in a synergistic effect; at the same time, a microscopic rough structure is formed on the fiber surface through the erosion effect, and the durability of the finishing effect is improved through the dual actions of mechanical nail anchoring and valence bond binding; a mixture of anionic sodium dodecylbenzenesulfonate and nonionic twain-80 is used as the surfactant to enhance the strength of the sodium dodecylbenzenesulfonate micelles, and at the same time can effectively reduce the viscosity of the hydrosol, thereby improving the stability and particle size uniformity of the hydrosol.

[0130] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly, and should not be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for surface modification of fibers, characterized in that, it includes the following steps: adjusting the pH value of deionized water to 3.0 - 4.0 with a buffer solution, then adding a surfactant and a protease, and the concentration of the protease in the system is 0.02 - 2.0 g / mL; performing modification treatment on the fabric, and then washing and drying the fabric.

2. The method according to claim 1, characterized in that, the dosage of the surfactant is 1 - 1.5 times the critical micelle concentration.

3. The method according to claim 1, characterized in that, the surfactant is a non - ionic surfactant.

4. The method according to claim 3, characterized in that, the surfactant is a nonylphenol polyoxyethylene ether type and / or an aliphatic polyoxyethylene ether type surfactant.

5. The method according to claim 1, characterized in that, the surfactant is a mixture composed of sodium dodecylbenzenesulfonate and twain - 80.

6. The method according to claim 5, characterized in that, the surfactant is a mixture composed of sodium dodecylbenzenesulfonate and twain - 80 with a mass ratio of 1∶0.1 - 0.

3.

7. The method according to claim 1, characterized in that, the buffer solution is a mixture composed of 0.1 - 0.3 mol / L disodium hydrogen phosphate and 0.05 - 0.2 mol / L citric acid.

8. The method according to claim 1, characterized in that, the modification treatment is carried out under the condition that the bath ratio is 1∶10 - 35.

9. The method according to claim 1, characterized in that, the protease is papain.

10. The method according to any one of claims 1 - 9, characterized in that, the steps further include a step of finishing the modified fabric with a polyalkylsiloxane hydrosol.

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