Lasting aromatic lyocell fiber of biological enzyme immobilized temperature-sensitive microcapsule and preparation method of lasting aromatic lyocell fiber

Abstract

The invention discloses a lasting aromatic lyocell fiber of a biological enzyme immobilized temperature-sensitive microcapsule and a preparation method of the lasting aromatic lyocell fiber, and relates to the technical field of polyester fabrics. The method comprises the steps that firstly, a temperature-sensitive microcapsule of a three-layer structure is prepared, an inner core contains aromatic substances of lavender essential oil, ambrota ether and rosin glycerin ester, a middle layer enables N-isopropylacrylamide monomers to be polymerized to form PNIPAM temperature-sensitive hydrogel, and a shell is a nanocellulose crystal-polydopamine compound; then spinning by taking the NMMO aqueous solution containing the microcapsules as an inner layer solution and taking the NMMO aqueous solution containing the eucalyptus pulp as an outer layer solution by adopting a coaxial micro-fluidic spinning technology; and finally carrying out crosslinking treatment through a biological enzyme coagulating bath, wherein the coagulating bath contains an NMMO aqueous solution, horse radish peroxidase and a hydrogen peroxide solution with gradient concentration. The aromatic lyocell fiber prepared by the invention has excellent temperature-sensitive aroma release performance and washing fastness, and solves the technical problems that microcapsules in traditional aromatic textiles are easy to break and fall off and aromatic substances are easy to volatilize.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional textile fiber preparation, in particular to a kind of biological enzyme immobilized temperature-sensitive microcapsule's persistent aromatic lyocell fiber and its preparation method. BACKGROUND

[0002] With the improvement of people's living standards and the growth of demand for functional textiles, aromatic functional textiles are widely concerned due to their unique sensory experience and potential health functions. Traditional aromatic textiles mainly use post-finishing technology to attach aromatic substances directly to the surface of fibers, but this method has problems such as volatile aromatic substances and poor washability.

[0003] The development of microcapsule technology provides a new way to solve the above problems. By embedding aromatic substances in microcapsules, the aromatic components can be effectively protected and released slowly. However, the microcapsules in the prior art still have the following technical defects in textile applications: the microcapsules have weak bonding force with the fiber matrix and are easily detached during washing; the mechanical strength of the microcapsule wall material is insufficient and is easily broken during friction and stretching; the release of aromatic substances is uncontrollable and lacks intelligent responsiveness; the preparation process is complex, the cost is high, and it is difficult to be industrialized.

[0004] Lyocell fiber, as a new generation of environmentally friendly regenerated cellulose fiber, has excellent mechanical properties, moisture absorption and air permeability, and biocompatibility, making it an ideal substrate for functional textiles. However, there is little research on combining microcapsule technology with lyocell fiber preparation, especially the lack of effective microcapsule immobilization technology and temperature-sensitive release mechanism.

[0005] Therefore, it is of great significance to develop a new type of biological enzyme immobilized temperature-sensitive microcapsule technology to achieve persistent immobilization of aromatic substances in lyocell fibers, which promotes the development of functional textiles. SUMMARY

[0006] To overcome the shortcomings of the prior art, the present application provides a biological enzyme immobilized temperature-sensitive microcapsule's persistent aromatic lyocell fiber and its preparation method, which solves the problems of microcapsule breakage and detachment, rapid loss of aromatic substances, poor washability and other technical problems, and realizes the persistent immobilization of aromatic substances.

[0007] The technical solution of the present application is as follows: A biological enzyme immobilized temperature-sensitive microcapsule's persistent aromatic lyocell fiber and its preparation method, comprising the following steps: S1: Preparation of nanocellulose crystal-polydopamine complex, 5 g of microcrystalline cellulose is hydrolyzed by sulfuric acid to prepare nanocellulose crystals, the microcrystalline cellulose is dispersed in 64% sulfuric acid, and the reaction is carried out at 65°C for 45 min, then the stable nanocellulose crystal suspension with a concentration of 2% is obtained by centrifugal separation, dialysis and ultrasonic dispersion, the nanocellulose crystal suspension is diluted to 0.5%, the pH is adjusted to 8.5, and 2 mg / mL of dopamine hydrochloride is added, and the reaction is stirred at room temperature for 8 hours, during which the dopamine is self-polymerized to form a polydopamine coating on the surface of the nanocellulose crystal. After the reaction is completed, the unreacted dopamine is removed by centrifugal separation and water washing to obtain the nanocellulose crystal-polydopamine complex.

[0008] Further, the centrifugal speed is set to 8000 rpm, and the centrifugal time is 10 min.

[0009] S2: Preparation of temperature-sensitive microcapsules, lavender essential oil, ambrox, glycerol ester of rosin, and octanol are mixed in a mass ratio to prepare a core solution; N-isopropyl acrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate are dissolved in deionized water to prepare an intermediate layer solution; the prepared nanocellulose crystal-polydopamine complex is dispersed in water, the concentration is adjusted to 1.2%-1.8%, and 0.5% of sodium alginate is added as a stabilizer to prepare a shell solution.

[0010] Then, the microcapsules are prepared by using a triple emulsion technique: the core solution is slowly added to liquid paraffin containing Span 80, and a high-speed homogenizer is used to homogenize at 8000 rpm for 3 min to prepare a first emulsion. The first emulsion is slowly added to the intermediate layer solution, and homogenized at 6000 rpm for 2 min to prepare a second emulsion. The second emulsion is slowly added to the shell solution, and homogenized at 4000 rpm for 1 min to prepare a triple emulsion.

[0011] The triple emulsion is placed in a 60°C water bath, nitrogen is introduced for protection, and the reaction is carried out for 2 hours to polymerize N-isopropyl acrylamide to form a PNIPAM (poly-N-isopropyl acrylamide) temperature-sensitive hydrogel. After the reaction is completed, the microcapsules are collected by centrifugal separation at a speed of 3000 rpm for 5 min, and washed with deionized water for 3 times to obtain the temperature-sensitive microcapsules.

[0012] Further, the mass percentage of lavender essential oil is 18%-22%, the mass percentage of ambrox is 10%-14%, the mass percentage of glycerol ester of rosin is 12%-16%, and the mass percentage of octanol is 48%-60%.

[0013] Further, the monomer N-isopropyl acrylamide has a mass percentage of 12% to 18%, the crosslinking agent N,N'-methylenebisacrylamide has a mass percentage of 0.8% to 1.2%, the initiator ammonium persulfate has a mass percentage of 0.5%, and deionized water has a mass percentage of 80.3% to 86.7%.

[0014] S3: Coaxial microfluidic spinning, dispersing the prepared temperature-sensitive microcapsules in a 90% NMMO aqueous solution (N-methylmorpholine-N-oxide) to uniformly disperse the microcapsules by stirring at 85°C for 2 hours to obtain an inner layer spinning solution; dissolving eucalyptus pulp in a 88% NMMO aqueous solution to dissolve at 95°C for 4 hours, and then cooling for standby to obtain an outer layer spinning solution; using a coaxial spinning process, spinning with a coaxial needle, and adjusting the flow rates of the inner layer and outer layer spinning solutions to control the distribution density of the microcapsules in the fiber, to prepare lyocell fibers under the conditions of a spinning temperature of 60°C and a fiber collection speed of 50 m / min.

[0015] Further, the microcapsules have a mass concentration of 4% to 6%, and the pulp has a mass concentration of 10% to 14%.

[0016] Further, the coaxial needle has an inner needle with an inner diameter of 200 μm and an outer needle with an inner diameter of 500 μm.

[0017] Further, the inner layer liquid has a flow rate of 0.8 to 1.2 mL / h, and the outer layer liquid has a flow rate of 3.5 to 4.5 mL / h.

[0018] S4: Crosslinking by a biological enzyme coagulation bath, the lyocell fibers prepared in step S3 are sequentially subjected to crosslinking treatment by three sections of coagulation bath, each section has a residence time of 8 minutes, the pH of each section of coagulation bath is adjusted to 7.0, and the temperature is controlled at 30°C. In this process, the horseradish peroxidase catalyzes the hydrogen peroxide to oxidize the polydopamine, so that the microcapsule shell and the cellulose matrix undergo a crosslinking reaction to form a covalent bond.

[0019] Further, the three-section gradient coagulation bath is prepared as follows: First section: NMMO aqueous solution with a concentration of 16% to 20%, horseradish peroxidase with a concentration of 80 to 120 U / mL, and hydrogen peroxide solution with a concentration of 0.025% to 0.035%; Second section: NMMO aqueous solution with a concentration of 8% to 12%, horseradish peroxidase with a concentration of 80 to 120 U / mL, and hydrogen peroxide solution with a concentration of 0.025% to 0.035%; Third section: NMMO aqueous solution with a concentration of 3% to 5%, horseradish peroxidase with a concentration of 80 to 120 U / mL, and hydrogen peroxide solution with a concentration of 0.025% to 0.035%.

[0020] S5: Post-processing: The cross-linked fiber is thoroughly washed with deionized water to remove residual NMMO and enzymes, and then dried at 60°C for 4 hours to obtain the final durable aromatic lyocell fiber.

[0021] The beneficial effects of this invention are: 1. This invention utilizes bio-enzyme immobilization technology to form strong covalent bonds between microcapsules and the fiber matrix, and the three-layer structure design effectively protects the aromatic components, maintaining a high aroma retention rate even after washing with water.

[0022] 2. This invention enables microcapsules to respond to body temperature through a PNIPAM temperature-sensitive layer, achieving intelligent release of aromatic substances under human body temperature conditions, thus meeting consumers' needs for product diversification and functionality.

[0023] 3. This invention provides good mechanical protection through a nanocellulose crystal-polydopamine composite shell, reducing the microcapsule rupture rate. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to the present invention.

[0025] Figure 2 A comparison chart showing the aroma retention rate of the long-lasting aromatic lyocell fiber immobilized with a bio-enzyme-based thermosensitive microcapsule according to the present invention under different conditions.

[0026] Figure 3 A comparison chart showing the microcapsule rupture rate of the bioenzyme-immobilized temperature-sensitive microcapsules of the present invention on durable aromatic lyocell fibers under different conditions. Detailed Implementation

[0027] The following embodiments further explain and illustrate the technical solution of the present invention. It is particularly noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention. (See attached...) Figure 1 The diagram shows a flowchart of a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method. The detailed preparation steps are as follows: 1. Preparation of nanocellulose crystal-polydopamine complex Take 5 g of microcrystalline cellulose, prepare nanocrystalline cellulose by sulfuric acid hydrolysis method, disperse the microcrystalline cellulose in 64% sulfuric acid, react at 65℃ for 45 minutes, then obtain a stable nanocrystalline cellulose suspension with a concentration of 2% by centrifugal separation, dialysis and ultrasonic dispersion, dilute the nanocrystalline cellulose suspension to 0.5%, adjust the pH to 8.5, add dopamine hydrochloride with a concentration of 2 mg / mL, stir at room temperature for 8 hours, and during the reaction process, dopamine occurs self-polymerization, forming a polydopamine coating on the surface of the nanocrystalline cellulose. After the reaction is completed, the unreacted dopamine is removed by centrifugal separation and water washing to obtain a nanocrystalline cellulose-polydopamine composite.

[0028] The centrifugal speed is set to 8000 rpm, and the centrifugal time is 10 minutes.

[0029] 2. Preparation of temperature-sensitive microcapsules 2.1 Preparation of core solution Mix lavender essential oil, ambrox, glycerol ester of rosin, and octanol according to the mass ratio, stir well to obtain the core solution.

[0030] Lavender essential oil mass percentage: 18% to 22%, ambrox mass percentage: 10% to 14%, glycerol ester of rosin mass percentage: 12% to 16%, and octanol mass percentage: 48% to 60% 2.2 Preparation of intermediate layer solution Dissolve N-isopropyl acrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate in deionized water to obtain the intermediate layer solution.

[0031] N-isopropyl acrylamide monomer mass percentage: 12% to 18%, crosslinking agent N,N'-methylenebisacrylamide mass percentage: 0.8% to 1.2%, initiator ammonium persulfate mass percentage: 0.5%, and deionized water mass percentage: 80.3% to 86.7% 2.3 Preparation of shell solution Disperse the prepared nanocrystalline cellulose-polydopamine composite in water, adjust the concentration to 1.2% to 1.8%, and add 0.5% sodium alginate as a stabilizer to prepare the shell solution.

[0032] 2.4 Preparation by triple emulsification The microcapsules are prepared by triple emulsification technology: Slowly add the core solution to liquid paraffin containing Span 80, and homogenize at 8000 rpm for 3 minutes with a high-speed homogenizer to obtain the first emulsion. Slowly add the first emulsion to the intermediate layer solution, and homogenize at 6000 rpm for 2 minutes to obtain the second emulsion. Slowly add the second emulsion to the shell solution, and homogenize at 4000 rpm for 1 minute to obtain the triple emulsion.

[0033] 2.5 Polymerization and solidification The triple emulsion was placed in a 60 °C water bath, and nitrogen was introduced to protect the reaction. After 2 hours of reaction, the N-isopropyl acrylamide was polymerized to form a PNIPAM temperature-sensitive hydrogel. After the reaction was completed, the microcapsules were collected by centrifugation at 3000 rpm for 5 minutes, and then washed with deionized water for 3 times to obtain the temperature-sensitive microcapsules.

[0034] 3. Coaxial microfluidic spinning 3.1 Preparation of spinning solution The prepared temperature-sensitive microcapsules were dispersed in a 90% NMMO aqueous solution, and stirred at 85 °C for 2 hours to uniformly disperse the microcapsules, thereby preparing an inner layer spinning solution. Then, the eucalyptus pulp was dissolved in a 88% NMMO aqueous solution, and dissolved at 95 °C for 4 hours, and then cooled for standby, thereby preparing an outer layer spinning solution.

[0035] The mass concentration of the microcapsules was 4% to 6%, and the mass concentration of the pulp was 10% to 14%.

[0036] 3.2 Coaxial spinning process The coaxial spinning process was adopted, and the coaxial needle was used for spinning. By adjusting the flow rates of the inner and outer layer spinning solutions, the distribution density of the microcapsules in the fiber could be controlled. Under the conditions of a spinning temperature of 60 °C and a take-up speed of 50 m / min, lyocell fibers were prepared.

[0037] The coaxial needle had an inner needle with an inner diameter of 200 μm and an outer needle with an inner diameter of 500 μm.

[0038] The flow rate of the inner layer solution was 0.8 to 1.2 mL / h, and the flow rate of the outer layer solution was 3.5 to 4.5 mL / h.

[0039] 4. Crosslinking by biological enzyme coagulation bath The fiber prepared in step 3.2 was sequentially subjected to crosslinking treatment by three sections of coagulation bath, and each section had a residence time of 8 minutes. The pH of each section of the coagulation bath was adjusted to 7.0, and the temperature was controlled at 30 °C. In this process, the horseradish peroxidase catalyzed the oxidation of polydopamine by hydrogen peroxide, so that the microcapsule shell and the cellulose matrix underwent a crosslinking reaction to form a covalent bond.

[0040] The three-section gradient coagulation bath was prepared as follows: The first section had a NMMO aqueous solution concentration of 16% to 20%, a horseradish peroxidase concentration of 80 to 120 U / mL, and a hydrogen peroxide solution concentration of 0.025% to 0.035%. The second section had a NMMO aqueous solution concentration of 8% to 12%, a horseradish peroxidase concentration of 80 to 120 U / mL, and a hydrogen peroxide solution concentration of 0.025% to 0.035%. The third segment: NMMO aqueous solution concentration 3% ~ 5%, horseradish peroxidase 80 ~ 120 U / mL, hydrogen peroxide solution concentration 0.025 ~ 0.035%.

[0041] 5. Post-treatment process The cross-linked treated fiber is washed with deionized water to remove residual NMMO and enzyme, and then dried at 60°C for 4 hours to obtain the final long-lasting fragrance lyocell fiber.

[0042] Example 1 A long-lasting fragrance lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules and a preparation method thereof, the detailed preparation steps are as follows: S1: Preparation of nanocellulose crystal-polydopamine composite, 5g microcrystalline cellulose is hydrolyzed with sulfuric acid to prepare nanocellulose crystals, the microcrystalline cellulose is dispersed in 64% sulfuric acid, and the reaction is carried out at 65°C for 45 minutes, then the stable nanocellulose crystal suspension with a concentration of 2% is obtained by centrifugal separation, dialysis and ultrasonic dispersion, the nanocellulose crystal suspension is diluted to 0.5%, the pH is adjusted to 8.5, and dopamine hydrochloride with a concentration of 2mg / mL is added, and the reaction is stirred at room temperature for 8 hours, during which dopamine is self-polymerized to form a polydopamine coating on the surface of the nanocellulose crystal. After the reaction is completed, the unreacted dopamine is removed by centrifugal separation and water washing to obtain the nanocellulose crystal-polydopamine composite.

[0043] The centrifugal speed is set to 8000rpm, and the centrifugal time is 10 minutes.

[0044] S2: Preparation of temperature-sensitive microcapsules Lavender essential oil, ambrox, glycerol ester of rosin, and octanol are mixed in a mass ratio, fully stirred and uniformly prepared to obtain a core solution; N-isopropyl acrylamide monomer, crosslinking agent N,N'-methylene bisacrylamide, and initiator ammonium persulfate are dissolved in deionized water to prepare an intermediate layer solution; the prepared nanocellulose crystal-polydopamine composite is dispersed in water, the concentration is adjusted to 1.5%, and 0.5% sodium alginate is added as a stabilizer to prepare an outer shell solution.

[0045] Then, the microcapsules are prepared by triple emulsification technology: the core solution is slowly added to liquid paraffin containing Span 80, and a high-speed homogenizer is used to homogenize at 8000rpm for 3 minutes to prepare a first emulsion. The first emulsion is slowly added to the intermediate layer solution, and homogenized at 6000rpm for 2 minutes to prepare a second emulsion. The second emulsion is slowly added to the outer shell solution, and homogenized at 4000rpm for 1 minute to prepare a triple emulsion.

[0046] The triple emulsion is placed in a 60℃ water bath, nitrogen is introduced for protection, and N-isopropyl acrylamide is polymerized to form a PNIPAM temperature-sensitive hydrogel after 2 hours of reaction. After the reaction is completed, the microcapsules are collected by centrifugation at a speed of 3000 rpm for 5 minutes, and then washed with deionized water for 3 times to obtain temperature-sensitive microcapsules.

[0047] Lavender essential oil mass percentage: 20%, farnesol mass percentage: 12%, glycerol ester of rosin mass percentage: 15%, octanol mass percentage: 53%.

[0048] N-isopropyl acrylamide monomer mass percentage: 15%, crosslinking agent N,N'-methylene bisacrylamide mass percentage: 1%, initiator ammonium persulfate mass percentage: 0.5%, deionized water mass percentage: 83.5%.

[0049] S3: coaxial microfluidic spinning, the prepared temperature-sensitive microcapsules are dispersed in a 90% NMMO aqueous solution, and the microcapsules are uniformly dispersed by stirring at 85℃ for 2 hours to prepare an inner spinning solution; then eucalyptus pulp is dissolved in a 88% NMMO aqueous solution, and the pulp is dissolved at 95℃ for 4 hours, and then cooled for standby to prepare an outer spinning solution; a coaxial spinning process is adopted, and spinning is performed by using a coaxial needle; the distribution density of the microcapsules in the fiber can be controlled by adjusting the flow rates of the inner and outer spinning solutions; under the conditions of a spinning temperature of 60℃ and a fiber collection speed of 50 m / min, lyocell fibers are prepared.

[0050] The mass concentration of the microcapsules is 5%, and the mass concentration of the pulp is 12%.

[0051] Coaxial needle, the inner diameter of the inner needle is 200μm, and the inner diameter of the outer needle is 500μm.

[0052] The flow rate of the inner liquid is 1mL / h, and the flow rate of the outer liquid is 4mL / h.

[0053] S4: biological enzyme coagulation bath crosslinking, the lyocell fibers prepared in step S3 are sequentially subjected to crosslinking treatment by passing through three sections of coagulation bath, and each section stays for 8 minutes; the pH of each section of the coagulation bath is adjusted to 7.0, and the temperature is controlled at 30℃. In this process, the horseradish peroxidase catalyzes the oxidation of polydopamine by hydrogen peroxide, so that the microcapsule shell and the cellulose matrix undergo crosslinking reaction to form covalent bond.

[0054] The three-section gradient coagulation bath is prepared as follows: First section: NMMO aqueous solution concentration 18%, horseradish peroxidase 100U / mL, hydrogen peroxide solution concentration 0.03%; Second section: NMMO aqueous solution concentration 10%, horseradish peroxidase 100U / mL, hydrogen peroxide solution concentration 0.03%; The third segment: NMMO aqueous solution concentration 4%, horseradish peroxidase 100 U / mL, hydrogen peroxide solution concentration 0.03%.

[0055] S5: post-processing process, after crosslinking treatment, the fiber is washed with deionized water, and the residual NMMO and enzyme are removed, and then dried at 60°C for 4 hours to obtain the final long-lasting fragrance lyocell fiber.

[0056] Example 2 A long-lasting fragrance lyocell fiber with a bio-enzyme immobilized temperature-sensitive microcapsule and a preparation method thereof, the detailed preparation steps are as follows: Referring to the long-lasting fragrance lyocell fiber with a bio-enzyme immobilized temperature-sensitive microcapsule and a preparation method thereof of Example 1, the difference is that, In the preparation process step S2, the mass percentage of lavender essential oil in the inner core solution is 18%, the mass percentage of ambrox is 10%, the mass percentage of glycerol ester of rosin is 12%, and the mass percentage of octanol is 60%; the concentration of nanocellulose crystal-polydopamine composite in the shell solution is 1.2%, the mass percentage of N-isopropyl acrylamide in the intermediate layer solution is 12%, the mass percentage of crosslinking agent is 0.8%, the mass percentage of initiator ammonium persulfate is 0.5%, and the mass percentage of deionized water is 86.7%; In the preparation process step S3, the concentration of microcapsules in the inner layer solution is 4%, and the concentration of pulp in the outer layer solution is 10%; the flow rate of the inner layer solution is 0.8 mL / h, and the flow rate of the outer layer solution is 3.5 mL / h; In the preparation process step S4, the NMMO concentrations of the three segments are 16%, 8%, and 3% respectively, the horseradish peroxidase is 80 U / mL, and the hydrogen peroxide solution concentration is 0.025%.

[0057] Example 3 A long-lasting fragrance lyocell fiber with a bio-enzyme immobilized temperature-sensitive microcapsule and a preparation method thereof, the detailed preparation steps are as follows: Referring to the long-lasting fragrance lyocell fiber with a bio-enzyme immobilized temperature-sensitive microcapsule and a preparation method thereof of Example 1, the difference is that, In the preparation process step S2, the mass percentage of lavender essential oil in the inner core solution is 18%, the mass percentage of ambrox is 10%, the mass percentage of glycerol ester of rosin is 12%, and the mass percentage of octanol is 60%; the concentration of nanocellulose crystal-polydopamine composite in the shell solution is 1.2%, the mass percentage of N-isopropyl acrylamide in the intermediate layer solution is 12%, the mass percentage of crosslinking agent is 0.8%, the mass percentage of initiator ammonium persulfate is 0.5%, and the mass percentage of deionized water is 86.7%; In the preparation process step S3, the concentration of microcapsules in the inner layer solution is 4%, and the concentration of pulp in the outer layer solution is 10%; the flow rate of the inner layer solution is 0.8 mL / h, and the flow rate of the outer layer solution is 3.5 mL / h; In the preparation process step S4, the three-stage NMMO concentration is 20%, 12%, and 5% respectively, the horseradish peroxidase is 120 U / mL, and the hydrogen peroxide solution concentration is 0.035%.

[0058] Comparative Example 1 The traditional finishing method was used to prepare the aromatic lyocell fiber. The ordinary lyocell fiber was immersed in a finishing solution containing lavender essential oil, and then dried and fixed.

[0059] Comparative Example 2 Referring to the preparation method of the persistent aromatic lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules in Example 1, a common gelatin-arabic gum wall material microcapsule was used, and the remaining steps were the same.

[0060] Comparative Example 3 Referring to the preparation method of the persistent aromatic lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules in Example 1, no horseradish peroxidase was added in the coagulation bath, only a common NMMO gradient coagulation bath was used, and the remaining steps were the same.

[0061] The persistent aromatic lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules and its preparation method were comprehensively compared in Examples 1-3 and Comparative Examples 1-3. The aromatic retention rate was determined according to the standard GB / T 8629-2017 “Home Laundering and Drying Procedures for Textile Testing”; and the microcapsule rupture rate was determined according to the standard ASTM D4966-22 “Standard Test Method for Abrasion Resistance of Textile Fabrics (Martindale Abrasion Tester Method”). The specific test comparison results are shown in Tables 1, 2 and 3, and Figs. 1-3. Figure 2 , and Figure 3 Table 1 Comparison of comprehensive performance of Examples 1-3 and Comparative Examples 1-3

[0062] From the above comparison results, in Comparative Example 1, the traditional finishing method was used to prepare the aromatic lyocell fiber, the ordinary lyocell fiber was immersed in a finishing solution containing lavender essential oil, and then dried and fixed, without a three-layer microcapsule structure, resulting in poor aromatic retention rate; in Comparative Example 2, a common gelatin-arabic gum wall material microcapsule was used, which could not effectively protect the aromatic substances and could not be covalently bonded with the fiber matrix, resulting in poor washing resistance, thus leading to low aromatic retention rate and high microcapsule rupture rate; in Comparative Example 3, no horseradish peroxidase was added in the coagulation bath, only a common NMMO gradient coagulation bath was used, resulting in lower aromatic retention rate compared with Example 1 and higher microcapsule rupture rate, because there was no horseradish peroxidase to catalyze the cross-linking of polydopamine, and the covalent bonding between the microcapsule and the fiber matrix could not be achieved, resulting in low washing resistance.​

Claims

1. A process for the preparation of a bio-enzyme immobilized temperature-sensitive microcapsule sustained-fragrance lyocell fiber, characterized in that, Comprise the following steps: S1: prepare nanocellulose crystals by sulfuric acid hydrolysis method, disperse microcrystalline cellulose in 64% sulfuric acid, react at 65℃ for 45 minutes, then obtain stable nanocellulose crystal suspension by centrifugal separation, dialysis and ultrasonic dispersion, dilute the nanocellulose crystal suspension, adjust the pH, add dopamine hydrochloride and stir at room temperature, dopamine polymerizes during the reaction, a polydopamine coating is formed on the surface of the nanocellulose crystal, then remove the unreacted dopamine by centrifugal separation and water washing to obtain nanocellulose crystal-polydopamine composite; S2: mix lavender essential oil, ambrox, glycerol ester of gum rosin and octanol according to mass ratio, stir well to prepare core solution; dissolve N-isopropyl acrylamide monomer, crosslinking agent N,N'-methylene bisacrylamide and initiator ammonium persulfate in deionized water to prepare middle layer solution; disperse the prepared nanocellulose crystal-polydopamine composite in water, adjust the concentration to 1.2%-1.8%, add 0.5% sodium alginate as stabilizer to prepare shell solution; then prepare temperature-sensitive microcapsules by triple emulsification technology; S3: dissolve the temperature-sensitive microcapsules prepared in step S2 and eucalyptus pulp in NMMO aqueous solution respectively, stir and cool to prepare inner and outer spinning solutions; use coaxial spinning process to spin with coaxial needle, control the distribution density of microcapsules in the fiber by adjusting the flow rate of inner and outer spinning solutions, prepare lyocell fiber under the conditions of spinning temperature 60℃ and fiber collection speed 50m / min; S4: crosslink the fiber prepared in step S3 by passing through three sections of coagulation bath in turn, each section stays for 8 minutes, adjust the pH of each section of coagulation bath to 7.0, and control the temperature at 30℃; S5: wash the crosslinked fiber after step S4 with deionized water to remove residual NMMO and enzyme, then dry at 60℃ for 4 hours to obtain the final long-lasting aromatic lyocell fiber.

2. The preparation method of the long-lasting aromatic lyocell fiber of the bioenzyme immobilized temperature-sensitive microcapsule according to claim 1, characterized in that the centrifugation in S1 is set at a speed of 8000rpm for 10 minutes.

3. The preparation method of the long-lasting aromatic lyocell fiber of the bioenzyme immobilized temperature-sensitive microcapsule according to claim 1, characterized in that the lavender essential oil, ambrox, glycerol ester of gum rosin and octanol in S2 are mixed according to mass ratio, specifically, the mass percentage of lavender essential oil is 18%-22%, the mass percentage of ambrox is 10%-14%, the mass percentage of glycerol ester of gum rosin is 12%-16%, and the mass percentage of octanol is 48%-60%.

4. The preparation method of the long-lasting aromatic lyocell fiber of the bioenzyme immobilized temperature-sensitive microcapsule according to claim 1, characterized in that ​ ​ The N-isopropyl acrylamide monomer, the crosslinking agent N,N'-methylene bisacrylamide and the initiator ammonium persulfate in S2 are respectively N-isopropyl acrylamide monomer 12-18% by mass, the crosslinking agent N,N'-methylene bisacrylamide 0.8-1.2% by mass, the initiator ammonium persulfate 0.5% by mass and deionized water 80.3-86.7% by mass. 5.The preparation method of the long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules according to claim 1, wherein, The triple emulsification technology in S2 is as follows: the inner core solution is slowly added into the liquid paraffin containing Span 80, and a first emulsion is prepared by homogenizing at 8000 rpm for 3 minutes; the first emulsion is slowly added into the intermediate layer solution, and a second emulsion is prepared by homogenizing at 6000 rpm for 2 minutes; the second emulsion is slowly added into the shell solution, and a third emulsion is prepared by homogenizing at 4000 rpm for 1 minute; the third emulsion is placed in a 60℃ water bath, and N-isopropyl acrylamide is polymerized to form a PNIPAM temperature-sensitive hydrogel by reacting for 2 hours under nitrogen protection; after the reaction is completed, the microcapsules are collected by centrifugation at 3000 rpm for 5 minutes, and then washed with deionized water for 3 times to obtain the temperature-sensitive microcapsules. 6.The preparation method of the long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules according to claim 1, wherein, The mass concentrations of the temperature-sensitive microcapsules and eucalyptus pulp in S3 are 4-6% and 10-14% respectively. 7.The preparation method of the long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules according to claim 1, wherein, The coaxial needle in S3 is selected to have an inner needle with an inner diameter of 200μm and an outer needle with an inner diameter of 500μm. 8.The preparation method of the long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules according to claim 1, wherein, The flow rates of the inner layer and outer layer spinning solutions in S3 are set to be 0.8-1.2mL / h and 3.5-4.5mL / h respectively. 9.The preparation method of the long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules according to claim 1, wherein, The three-stage coagulation bath in S4 is prepared as follows: The first stage: NMMO aqueous solution 16-20%, horseradish peroxidase 80-120U / mL, and hydrogen peroxide solution 0.025-0.035%; The second stage: NMMO aqueous solution 8-12%, horseradish peroxidase 80-120U / mL, and hydrogen peroxide solution 0.025-0.035%; The third stage: NMMO aqueous solution 3-5%, horseradish peroxidase 80-120U / mL, and hydrogen peroxide solution 0.025-0.035%. 10.A long-lasting fragrant lyocell fiber with bio-enzyme immobilized temperature-sensitive microcapsules prepared by the preparation method according to any one of claims 1-9. The bio-enzyme immobilized temperature-sensitive microcapsule persistent fragrance lyocell fiber has a microcapsule breakage rate of less than 4% and a fragrance retention rate of more than 87%.

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