A bio-enzyme immobilized temperature-sensitive microcapsule sustained-fragrance lyocell fiber and a preparation method thereof

Abstract

The application discloses a kind of biological enzyme immobilization temperature-sensitive microcapsule's long-lasting fragrance lyocell fiber and its preparation method, it is related to polyester fabric technical field.The method includes: first, the temperature-sensitive microcapsule with three-layer structure is prepared, the core contains lavender essential oil, ambrox and rosin glyceride fragrance, middle layer makes N-isopropyl acrylamide monomer polymerization and forms PNIPAM temperature-sensitive hydrogel, shell is nanocrystalline cellulose-polydopamine compound;Then using coaxial microfluidic spinning technology, with microcapsule NMMO aqueous solution as inner liquid, with eucalyptus pulp NMMO aqueous solution as outer liquid spinning;Finally, through biological enzyme coagulation bath crosslinking treatment, coagulation bath contains concentration gradient NMMO aqueous solution, horseradish peroxidase and hydrogen peroxide solution.The fragrance lyocell fiber prepared by the application has excellent temperature-sensitive fragrance release performance and washing resistance, solves the technical problems that microcapsule is easy to break off in traditional fragrance textiles, and fragrance material is easy to evaporate.

Description

Technical Field

[0001] This invention relates to the field of functional textile fiber preparation technology, specifically to a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method. Background Technology

[0002] With the improvement of people's living standards and the growth in demand for functional textiles, aromatic functional textiles have received widespread attention due to their unique sensory experience and potential health benefits. Traditional aromatic textiles mainly rely on finishing techniques to directly attach aromatic substances to the fiber surface, but this method suffers from problems such as the easy volatilization of aromatic substances and poor washability.

[0003] The development of microencapsulation technology has provided a new approach to solving the above problems. By encapsulating aromatic substances in microcapsules, aromatic components can be effectively protected and slow release can be achieved. However, existing microcapsules still have the following technical drawbacks in textile applications: the bonding force between microcapsules and the fiber matrix is ​​not strong, and they are prone to detachment during washing; the mechanical strength of the microcapsule wall material is insufficient, and it is prone to breakage during friction and stretching; the release of aromatic substances is uncontrollable and lacks intelligent responsiveness; the preparation process is complex and costly, making it difficult to industrialize.

[0004] Lyocell fiber, as a new generation of environmentally friendly regenerated cellulose fiber, possesses excellent mechanical properties, moisture absorption and breathability, and biocompatibility, making it an ideal substrate for the preparation of functional textiles. However, there is currently limited research combining microencapsulation technology with lyocell fiber preparation, particularly lacking effective microencapsulation techniques and thermosensitive controlled-release mechanisms.

[0005] Therefore, developing a novel bio-enzyme-immobilized temperature-sensitive microcapsule technology to achieve long-term immobilization of aromatic substances in lyocell fibers is of great significance for promoting the development of functional textiles. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method, thereby solving the technical problems of easy rupture and detachment of microcapsules, rapid loss of aromatic substances, and poor washability in aromatic textiles, and achieving durable immobilization of aromatic substances.

[0007] The technical solution of the present invention is as follows:

[0008] A durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method, comprising the following steps:

[0009] S1: Preparation of the nanocellulose crystal-polydopamine complex: 5g of microcrystalline cellulose was prepared into nanocellulose crystals by sulfuric acid hydrolysis. The microcrystalline cellulose was dispersed in 64% sulfuric acid and reacted at 65℃ for 45 minutes. Then, a stable nanocellulose crystal suspension with a concentration of 2% was obtained by centrifugation, dialysis, and ultrasonic dispersion. The nanocellulose crystal suspension was diluted to 0.5%, the pH was adjusted to 8.5, and dopamine hydrochloride with a concentration of 2mg / mL was added. The mixture was stirred and reacted at room temperature for 8 hours. During the reaction, dopamine underwent self-polymerization, forming a polydopamine coating on the surface of the nanocellulose crystals. After the reaction was completed, unreacted dopamine was removed by centrifugation and washing with water to obtain the nanocellulose crystal-polydopamine complex.

[0010] Furthermore, the centrifuge speed was set to 8000 rpm and the centrifugation time to 10 minutes.

[0011] S2: Preparation of thermosensitive microcapsules: Lavender essential oil, ambroxol, rosin glycerol ester, and octanol were mixed in a mass ratio and stirred thoroughly to obtain a core solution; N-isopropylacrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate were dissolved in deionized water to obtain an intermediate layer solution; the prepared nanocellulose crystal-polydopamine complex was dispersed in water, the concentration was adjusted to 1.2% to 1.8%, and 0.5% sodium alginate was added as a stabilizer to obtain an outer shell solution.

[0012] Then, a triple emulsification technique was used to prepare microcapsules: the core solution was slowly added to liquid paraffin containing Span 80, and homogenized at 8000 rpm for 3 minutes using a high-speed homogenizer to obtain the first emulsion. The first emulsion was slowly added to the intermediate layer solution, and homogenized at 6000 rpm for 2 minutes to obtain the second emulsion. The second emulsion was slowly added to the shell solution, and homogenized at 4000 rpm for 1 minute to obtain the triple emulsion.

[0013] The triple emulsion was placed in a 60°C water bath under nitrogen protection and reacted for 2 hours to polymerize N-isopropylacrylamide into PNIPAM (poly-N-isopropylacrylamide) thermosensitive hydrogel. After the reaction was completed, the microcapsules were collected by centrifugation at 3000 rpm for 5 minutes and washed three times with deionized water to obtain thermosensitive microcapsules.

[0014] Furthermore, the percentage by weight of lavender essential oil is 18%–22%, ambroxol is 10%–14%, rosin glycerides are 12%–16%, and octanol is 48%–60%.

[0015] Furthermore, the mass percentages of N-isopropylacrylamide monomer are 12%–18%, the mass percentages of crosslinking agent N,N'-methylenebisacrylamide are 0.8%–1.2%, the mass percentages of initiator ammonium persulfate are 0.5%, and the mass percentages of deionized water are 80.3%–86.7%.

[0016] S3: Coaxial microfluidic spinning: The prepared temperature-sensitive microcapsules were dispersed in a 90% NMMO aqueous solution (N-methylmorpholine-N-oxide) and stirred at 85°C for 2 hours to ensure uniform dispersion of the microcapsules, thus obtaining the inner spinning solution; then, eucalyptus pulp was dissolved in an 88% NMMO aqueous solution at 95°C for 4 hours, and then cooled for later use, thus obtaining the outer spinning solution; using a coaxial spinning process with a coaxial needle, the distribution density of microcapsules in the fiber can be controlled by adjusting the flow rate of the inner and outer spinning solutions. Lyocell fibers were prepared under the conditions of a spinning temperature of 60°C and a take-up speed of 50 m / min.

[0017] Furthermore, the microcapsule mass concentration is 4%–6%, and the pulp mass concentration is 10%–14%.

[0018] Furthermore, for the coaxial needle, the inner needle diameter is selected as 200μm and the outer needle inner diameter is selected as 500μm.

[0019] Furthermore, the inner layer fluid flow rate is 0.8–1.2 mL / h, and the outer layer fluid flow rate is 3.5–4.5 mL / h.

[0020] S4: Bioenzymatic coagulation bath crosslinking. The lyocell fibers prepared in step S3 were sequentially passed through three coagulation baths for crosslinking treatment, with a residence time of 8 minutes in each stage. The pH of each coagulation bath was adjusted to 7.0, and the temperature was controlled at 30℃. During this process, horseradish peroxidase catalyzes the oxidation of polydopamine with hydrogen peroxide, causing the microcapsule shell to undergo a crosslinking reaction with the cellulose matrix, forming covalent bonds.

[0021] Furthermore, the three-stage gradient coagulation bath is prepared as follows:

[0022] First stage: NMMO aqueous solution concentration 16%–20%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%;

[0023] Second section: NMMO aqueous solution concentration 8%–12%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%;

[0024] The third step: NMMO aqueous solution concentration 3%–5%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%.

[0025] 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.

[0026] The beneficial effects of this invention are:

[0027] 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.

[0028] 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.

[0029] 3. This invention provides good mechanical protection through a nanocellulose crystal-polydopamine composite shell, reducing the microcapsule rupture rate. Attached Figure Description

[0030] 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.

[0031] 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.

[0032] 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

[0033] 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:

[0034] 1. Preparation of nanocellulose crystal-polydopamine complex

[0035] 5g of microcrystalline cellulose was used to prepare nanocrystalline cellulose crystals via sulfuric acid hydrolysis. The microcrystalline cellulose was dispersed in 64% sulfuric acid and reacted at 65℃ for 45 minutes. Then, a stable nanocrystalline cellulose crystal suspension with a concentration of 2% was obtained by centrifugation, dialysis, and ultrasonic dispersion. The nanocrystalline cellulose crystal suspension was diluted to 0.5%, the pH was adjusted to 8.5, and dopamine hydrochloride with a concentration of 2 mg / mL was added. The mixture was stirred at room temperature for 8 hours. During the reaction, dopamine underwent self-polymerization, forming a polydopamine coating on the surface of the nanocrystalline cellulose crystals. After the reaction was complete, unreacted dopamine was removed by centrifugation and washing with water to obtain the nanocrystalline cellulose-polydopamine complex.

[0036] Set the centrifuge speed to 8000 rpm and the centrifugation time to 10 minutes.

[0037] 2. Preparation of temperature-sensitive microcapsules

[0038] 2.1 Preparation of kernel solution

[0039] Lavender essential oil, ambroxol, rosin glyceryl ester, and octanol were mixed in a certain mass ratio and stirred thoroughly to obtain the kernel solution.

[0040] Lavender essential oil (by weight): 18%–22%; Ambroxol (by weight): 10%–14%; Rosin glyceryl esters (by weight): 12%–16%; Octyl alcohol (by weight): 48%–60%.

[0041] 2.2 Preparation of Intermediate Layer Solution

[0042] An intermediate layer solution was prepared by dissolving N-isopropylacrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate in deionized water.

[0043] N-Isopropylacrylamide monomer mass percentage: 12%–18%, crosslinking agent N,N'-methylenebisacrylamide mass percentage: 0.8%–1.2%, initiator ammonium persulfate mass percentage: 0.5%, deionized water mass percentage: 80.3%–86.7%.

[0044] 2.3 Preparation of the outer shell solution

[0045] The prepared nanocellulose crystal-polydopamine complex was dispersed in water and the concentration was adjusted to 1.2%–1.8%. Sodium alginate 0.5% was added as a stabilizer to prepare the shell solution.

[0046] 2.4 Triple Emulsification Preparation

[0047] The microcapsules are prepared using a triple emulsification technology:

[0048] The core solution was slowly added to liquid paraffin containing Span 80, and homogenized at 8000 rpm for 3 minutes using a high-speed homogenizer to obtain the first emulsion. The first emulsion was slowly added to the intermediate layer solution, and homogenized at 6000 rpm for 2 minutes to obtain the second emulsion. The second emulsion was slowly added to the outer shell solution, and homogenized at 4000 rpm for 1 minute to obtain the triple emulsion.

[0049] 2.5 Polymerization and Curing

[0050] The triple emulsion was placed in a 60°C water bath under nitrogen protection and reacted for 2 hours to polymerize N-isopropylacrylamide into PNIPAM thermosensitive hydrogel. After the reaction was completed, the microcapsules were collected by centrifugation at 3000 rpm for 5 minutes and washed three times with deionized water to obtain thermosensitive microcapsules.

[0051] 3. Coaxial microfluidic spinning

[0052] 3.1 Preparation of spinning solution

[0053] The prepared temperature-sensitive microcapsules were dispersed in a 90% NMMO aqueous solution and stirred at 85°C for 2 hours to ensure uniform dispersion, thus obtaining the inner spinning solution. Then, eucalyptus pulp was dissolved in an 88% NMMO aqueous solution and dissolved at 95°C for 4 hours, followed by cooling for later use, thus obtaining the outer spinning solution.

[0054] The microcapsule concentration is 4%–6%, and the pulp concentration is 10%–14%.

[0055] 3.2 Coaxial spinning process

[0056] Using a coaxial spinning process with a coaxial needle, the distribution density of microcapsules in the fiber can be controlled by adjusting the flow rate of the inner and outer spinning solutions. Lyocell fibers were prepared under the conditions of a spinning temperature of 60℃ and a take-up speed of 50m / min.

[0057] The coaxial needles are selected with an inner needle diameter of 200μm and an outer needle inner diameter of 500μm.

[0058] The inner layer fluid flow rate is 0.8–1.2 mL / h, and the outer layer fluid flow rate is 3.5–4.5 mL / h.

[0059] 4. Bioenzyme coagulation bath crosslinking

[0060] The fibers prepared in step 3.2 were sequentially passed through a three-stage coagulation bath for cross-linking treatment, with a residence time of 8 minutes in each stage. The pH of each coagulation bath was adjusted to 7.0, and the temperature was controlled at 30°C. During this process, horseradish peroxidase catalyzes the oxidation of polydopamine with hydrogen peroxide, causing the microcapsule shell to undergo a cross-linking reaction with the cellulose matrix, forming covalent bonds.

[0061] The three-stage gradient coagulation bath was prepared as follows:

[0062] First stage: NMMO aqueous solution concentration 16%–20%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%;

[0063] Second section: NMMO aqueous solution concentration 8%–12%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%;

[0064] The third step: NMMO aqueous solution concentration 3%–5%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%.

[0065] 5. Post-processing techniques

[0066] The cross-linked fibers were 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 fibers.

[0067] Example 1

[0068] A durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method are disclosed below:

[0069] S1: Preparation of the nanocellulose crystal-polydopamine complex: 5g of microcrystalline cellulose was prepared into nanocellulose crystals by sulfuric acid hydrolysis. The microcrystalline cellulose was dispersed in 64% sulfuric acid and reacted at 65℃ for 45 minutes. Then, a stable nanocellulose crystal suspension with a concentration of 2% was obtained by centrifugation, dialysis, and ultrasonic dispersion. The nanocellulose crystal suspension was diluted to 0.5%, the pH was adjusted to 8.5, and dopamine hydrochloride with a concentration of 2mg / mL was added. The mixture was stirred and reacted at room temperature for 8 hours. During the reaction, dopamine underwent self-polymerization, forming a polydopamine coating on the surface of the nanocellulose crystals. After the reaction was completed, unreacted dopamine was removed by centrifugation and washing with water to obtain the nanocellulose crystal-polydopamine complex.

[0070] Set the centrifuge speed to 8000 rpm and the centrifugation time to 10 minutes.

[0071] S2: Preparation of temperature-sensitive microcapsules

[0072] Lavender essential oil, ambroxol, rosin glycerol ester, and octanol were mixed in a mass ratio and stirred thoroughly to obtain the core solution; N-isopropylacrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate were dissolved in deionized water to obtain the intermediate layer solution; the prepared nanocellulose crystal-polydopamine complex was dispersed in water, the concentration was adjusted to 1.5%, and 0.5% sodium alginate was added as a stabilizer to obtain the outer shell solution.

[0073] Then, a triple emulsification technique was used to prepare microcapsules: the core solution was slowly added to liquid paraffin containing Span 80, and homogenized at 8000 rpm for 3 minutes using a high-speed homogenizer to obtain the first emulsion. The first emulsion was slowly added to the intermediate layer solution, and homogenized at 6000 rpm for 2 minutes to obtain the second emulsion. The second emulsion was slowly added to the shell solution, and homogenized at 4000 rpm for 1 minute to obtain the triple emulsion.

[0074] The triple emulsion was placed in a 60°C water bath under nitrogen protection and reacted for 2 hours to polymerize N-isopropylacrylamide into PNIPAM thermosensitive hydrogel. After the reaction was completed, the microcapsules were collected by centrifugation at 3000 rpm for 5 minutes and washed three times with deionized water to obtain thermosensitive microcapsules.

[0075] Lavender essential oil by weight percentage: 20%, ambroxol by weight percentage: 12%, rosin glyceryl ester by weight percentage: 15%, octanol by weight percentage: 53%.

[0076] N-Isopropylacrylamide monomer mass percentage: 15%, crosslinking agent N,N'-methylenebisacrylamide mass percentage: 1%, initiator ammonium persulfate mass percentage: 0.5%, deionized water mass percentage: 83.5%.

[0077] S3: Coaxial microfluidic spinning: The prepared temperature-sensitive microcapsules were dispersed in a 90% NMMO aqueous solution and stirred at 85°C for 2 hours to ensure uniform dispersion, thus obtaining the inner spinning solution. Then, eucalyptus pulp was dissolved in an 88% NMMO aqueous solution at 95°C for 4 hours, and then cooled for later use, thus obtaining the outer spinning solution. Coaxial spinning was performed using a coaxial needle. The distribution density of microcapsules in the fiber could be controlled by adjusting the flow rates of the inner and outer spinning solutions. Lyocell fibers were prepared under the conditions of a spinning temperature of 60°C and a take-up speed of 50 m / min.

[0078] The microcapsule concentration was 5%, and the pulp concentration was 12%.

[0079] The coaxial needles are selected with an inner needle diameter of 200μm and an outer needle inner diameter of 500μm.

[0080] The inner layer fluid flow rate is 1 mL / h, and the outer layer fluid flow rate is 4 mL / h.

[0081] S4: Bioenzymatic coagulation bath crosslinking. The lyocell fibers prepared in step S3 were sequentially passed through three coagulation baths for crosslinking treatment, with a residence time of 8 minutes in each stage. The pH of each coagulation bath was adjusted to 7.0, and the temperature was controlled at 30℃. During this process, horseradish peroxidase catalyzes the oxidation of polydopamine with hydrogen peroxide, causing the microcapsule shell to undergo a crosslinking reaction with the cellulose matrix, forming covalent bonds.

[0082] The three-stage gradient coagulation bath was prepared as follows:

[0083] First section: NMMO aqueous solution concentration 18%, horseradish peroxidase 100 U / mL, hydrogen peroxide solution concentration 0.03%;

[0084] Second section: NMMO aqueous solution concentration 10%, horseradish peroxidase 100U / mL, hydrogen peroxide solution concentration 0.03%;

[0085] The third section contains 4% NMMO aqueous solution, 100 U / mL horseradish peroxidase, and 0.03% hydrogen peroxide solution.

[0086] 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.

[0087] Example 2

[0088] A durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method are disclosed below:

[0089] The difference between this and Example 1 is that a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method.

[0090] In step S2 of the preparation process, the core solution contains 18% lavender essential oil, 10% ambroxol, 12% rosin glycerol ester, and 60% octanol by mass; the outer shell solution contains 1.2% nanocellulose crystal-polydopamine complex; and the intermediate layer solution contains 12% N-isopropylacrylamide, 0.8% crosslinking agent, 0.5% ammonium persulfate initiator, and 86.7% deionized water by mass.

[0091] In step S3 of the preparation process, the concentration of microcapsules in the inner layer liquid is 4%, and the concentration of pulp in the outer layer liquid is 10%; the flow rate of the inner layer liquid is 0.8 mL / h, and the flow rate of the outer layer liquid is 3.5 mL / h.

[0092] In step S4 of the preparation process, the concentrations of NMMO in the three stages are 16%, 8%, and 3%, respectively; horseradish peroxidase is 80 U / mL; and hydrogen peroxide solution concentration is 0.025%.

[0093] Example 3

[0094] A durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method are disclosed below:

[0095] The difference between this and Example 1 is that a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules and its preparation method.

[0096] In step S2 of the preparation process, the core solution contains 22% lavender essential oil, 14% ambroxol, 16% rosin glycerol ester, and 48% octanol by mass; the outer shell solution contains 1.8% nanocellulose crystal-polydopamine complex; and the intermediate layer solution contains 18% N-isopropylacrylamide, 1.2% crosslinking agent, 0.5% ammonium persulfate initiator, and 80.3% deionized water by mass.

[0097] In step S3 of the preparation process, the concentration of microcapsules in the inner layer liquid is 6%, and the concentration of pulp in the outer layer liquid is 14%; the flow rate of the inner layer liquid is 1.2 mL / h, and the flow rate of the outer layer liquid is 4.5 mL / h.

[0098] In step S4 of the preparation process, the concentrations of NMMO in the three stages are 20%, 12%, and 5%, respectively; horseradish peroxidase is 120 U / mL; and hydrogen peroxide solution concentration is 0.035%.

[0099] Comparative Example 1

[0100] Aromatic lyocell fibers were prepared using traditional finishing methods. Ordinary lyocell fibers were impregnated in a finishing solution containing lavender essential oil, and then dried and fixed.

[0101] Comparative Example 2

[0102] The method for preparing a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules is described in Example 1, but ordinary gelatin-gum arabic wall material microcapsules are used, and the remaining steps are the same.

[0103] Comparative Example 3

[0104] The method of preparing a long-lasting aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules is described in Example 1, but horseradish peroxidase is not added to the coagulation bath; only a conventional NMMO gradient coagulation bath is used, and the remaining steps are the same.

[0105] This paper compares the comprehensive performance of a bio-enzyme-immobilized temperature-sensitive microcapsule-based long-lasting aromatic lyocell fiber and its preparation method, based on Examples 1-3 and Comparative Examples 1-3. The aroma retention rate was determined according to standard GB / T 8629-2017 "Testing of Textiles - Household Washing and Drying Procedures"; the microcapsule rupture rate was determined according to standard ASTM D4966-22 "Standard Test Methods for Abrasion Resistance of Textile Fabrics (Martindale Abrasion Tester Method)". Specific test comparison results are shown in Table 1 and Appendix. Figure 2 Appendix Figure 3 As shown:

[0106] Table 1. Comparison of overall performance between Examples 1-3 and Comparative Examples 1-3

[0107]

[0108] As can be seen from the above comparison results, in Comparative Example 1, the aromatic lyocell fiber was prepared using a traditional finishing method, in which ordinary lyocell fiber was impregnated in a finishing solution containing lavender essential oil and then dried and fixed. The absence of a three-layer microcapsule structure resulted in poor aroma retention. In Comparative Example 2, ordinary gelatin-gum arabic wall material microcapsules were used, which could not effectively protect the aromatic substances and could not be covalently bonded to the fiber matrix, resulting in poor wash resistance, low aroma retention, and high microcapsule rupture rate. In Comparative Example 3, no horseradish peroxidase was added to the coagulation bath; only an ordinary NMMO gradient coagulation bath was used. This resulted in a lower aroma retention rate and a higher microcapsule rupture rate compared to Example 1 because the absence of horseradish peroxidase catalyzing polydopamine crosslinking prevented the covalent bonding between the microcapsules and the fiber matrix, leading to lower wash resistance.

Claims

1. A method for preparing a long-lasting aromatic lyocell fiber immobilized with bio-enzyme-loaded thermosensitive microcapsules, characterized in that, Includes the following steps: S1: Nanocellulose crystals were prepared by sulfuric acid hydrolysis. Microcrystalline cellulose was dispersed in 64% sulfuric acid and reacted at 65°C for 45 minutes. Then, a stable nanocellulose crystal suspension was obtained by centrifugation, dialysis and ultrasonic dispersion. The nanocellulose crystal suspension was diluted, the pH was adjusted, and dopamine hydrochloride was added and stirred at room temperature. During the reaction, dopamine underwent self-polymerization and formed a polydopamine coating on the surface of the nanocellulose crystals. Then, unreacted dopamine was removed by centrifugation and water washing to obtain the nanocellulose crystal-polydopamine complex. S2: Lavender essential oil, ambroxol, rosin glycerol ester, and octanol were mixed in a mass ratio and stirred thoroughly to obtain the core solution; N-isopropylacrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate were dissolved in deionized water to obtain the intermediate layer solution; the prepared nanocellulose crystal-polydopamine complex was dispersed in water, the concentration was adjusted to 1.2%–1.8%, and 0.5% sodium alginate was added as a stabilizer to obtain the outer shell solution; then, temperature-sensitive microcapsules were prepared using a triple emulsification technique. S3: The temperature-sensitive microcapsules prepared in step S2 and eucalyptus pulp are dissolved in NMMO aqueous solution, stirred and cooled for later use, thus obtaining the inner layer spinning solution and the outer layer spinning solution; coaxial spinning process is adopted, and spinning is performed with coaxial needles. The distribution density of microcapsules in the fiber can be controlled by adjusting the flow rate of the inner and outer layer spinning solutions. Lyocell fiber is prepared under the conditions of spinning temperature of 60℃ and take-up speed of 50m / min. S4: The fibers prepared in step S3 are sequentially subjected to crosslinking treatment through three coagulation baths. The first stage: NMMO aqueous solution concentration 16%–20%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%; the second stage: NMMO aqueous solution concentration 8%–12%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%; the third stage: NMMO aqueous solution concentration 3%–5%, horseradish peroxidase 80–120 U / mL, hydrogen peroxide solution concentration 0.025–0.035%. Each stage lasts for 8 minutes. The pH of each coagulation bath is adjusted to 7.0, and the temperature is controlled at 30℃. S5: Wash the cross-linked fiber from step S4 thoroughly with deionized water to remove residual NMMO and enzymes, and then dry it at 60°C for 4 hours to obtain the final durable aromatic lyocell fiber.

2. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The centrifugation described in S1 is set to a speed of 8000 rpm and a centrifugation time of 10 minutes.

3. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The lavender essential oil, ambroxol, rosin glycerol ester, and octanol described in S2 are mixed in the following mass ratios: lavender essential oil mass percentage: 18%–22%, ambroxol mass percentage: 10%–14%, rosin glycerol ester mass percentage: 12%–16%, and octanol mass percentage: 48%–60%.

4. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The N-isopropylacrylamide monomer, crosslinking agent N,N'-methylenebisacrylamide, and initiator ammonium persulfate described in S2 have the following composition: N-isopropylacrylamide monomer: 12%–18% by mass; crosslinking agent N,N'-methylenebisacrylamide: 0.8%–1.2% by mass; initiator ammonium persulfate: 0.5% by mass; and deionized water: 80.3%–86.7% by mass.

5. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The triple emulsification technology described in S2 is as follows: The core solution is slowly added to liquid paraffin containing Span 80, and homogenized at 8000 rpm for 3 minutes using a high-speed homogenizer to obtain the first emulsion. The first emulsion is slowly added to the intermediate layer solution and homogenized at 6000 rpm for 2 minutes to obtain the second emulsion. The second emulsion is slowly added to the outer shell solution and homogenized at 4000 rpm for 1 minute to obtain the triple emulsion. The triple emulsion is placed in a 60°C water bath under nitrogen protection and reacted for 2 hours to polymerize N-isopropylacrylamide to form PNIPAM thermosensitive hydrogel. After the reaction is complete, the microcapsules are collected by centrifugation at 3000 rpm for 5 minutes and washed three times with deionized water to obtain thermosensitive microcapsules.

6. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The temperature-sensitive microcapsules and eucalyptus pulp described in S3 have mass concentrations of 4%–6% and 10%–14%, respectively.

7. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The coaxial needle described in S3 has an inner needle diameter of 200μm and an outer needle inner diameter of 500μm.

8. The method for preparing a durable aromatic lyocell fiber with bio-enzyme-immobilized temperature-sensitive microcapsules according to claim 1, characterized in that, The flow rates of the inner spinning solution and the outer spinning solution described in S3 are set to 0.8–1.2 mL / h and 3.5–4.5 mL / h, respectively.

9. A durable aromatic lyocell fiber with bio-enzyme-immobilized thermosensitive microcapsules prepared by the preparation method according to any one of claims 1-8, characterized in that, The aforementioned bio-enzyme-immobilized temperature-sensitive microcapsules of durable aromatic lyocell fiber have a microcapsule rupture rate of less than 4% and an aroma retention rate of more than 87%.

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