Degradable bio-based aromatic microcapsules, methods for their preparation and their use in chemical fibers

Abstract

The application belongs to the technical field of polymer materials and application in fibers, and particularly relates to a degradable bio-based aromatic microcapsule, a preparation method thereof and application of the degradable bio-based aromatic microcapsule in chemical fibers. The preparation method of the degradable bio-based aromatic microcapsule comprises the following steps: preparing primary bio-based degradable aromatic microcapsules by using silica aerogel and a composite oily capsule core material, dispersing into a bio-based emulsifier dispersion, and preparing second bio-based degradable aromatic microcapsules with protein as a capsule wall. The application of the degradable bio-based aromatic microcapsule comprises melt spinning or wet spinning to obtain a primary fiber, and then plasma treatment is performed on the primary fiber to obtain a chemical fiber with aromatic functions. The degradable bio-based aromatic microcapsule provided by the application has the characteristics of a wide particle size range, high coating rate, good heat resistance, excellent antibacterial property and degradability. The application also provides a preparation method and application thereof.

Description

Technical Field

[0001] This invention belongs to the technical field of polymer materials and their application in fibers, specifically relating to biodegradable bio-based aromatic microcapsules, their preparation methods, and their application in chemical fibers. Background Technology

[0002] Microencapsulation technology is an advanced material preparation technology that encapsulates active substances within a shell material by constructing a "core-shell" structure. This enables the isolation and protection of active substances and precise controlled release, thereby improving their stability, efficacy, and functionality. The release of active substances can be regulated through various mechanisms such as shearing, dissolution, heating, pH adjustment, or enzyme activity. Microencapsulation technology has been widely applied in functional textiles, cosmetics, pharmaceuticals, and food. With increasing societal demands for environmental protection and health, microencapsulation technology increasingly emphasizes the selection of bio-based materials, good biocompatibility, simple and environmentally friendly preparation processes, and the natural biodegradability of materials. Bio-based microcapsules refer to products that use some or all of their bio-based materials as raw materials or excipients in their preparation process, effectively reducing dependence on fossil resources such as petroleum and lowering carbon emissions.

[0003] Fragrances possess properties such as relieving anxiety, calming pain, and deodorizing / sterilizing, and are widely used in textiles, cosmetics, pharmaceuticals, and food. However, fragrances are highly volatile, especially when heated, resulting in a significantly increased evaporation rate and poor stability. This leads to short-lasting fragrance and poor durability during use and storage, thus limiting their application. Microencapsulation of fragrances is an effective way to improve their stability and extend their fragrance duration. Fragrance microcapsules can prevent aromatic substances from being directly affected by heat, light, and temperature, thus avoiding deterioration or volatilization loss. This allows for slow release of fragrance, making the fragrance last longer, while also improving the stability and convenience of storage, transportation, and application.

[0004] Currently, aromatic microcapsules and their preparation methods on the market mainly have the following problems: First, the microcapsule wall materials are made of synthetic polymer wall materials, such as amino resins, polyurethanes, and acrylic resins. Although they have the advantage of stability, they pose a risk of releasing aldehydes and are not recyclable or degradable, resulting in poor environmental and health performance and failing to meet the requirements of low-carbon and environmental protection. Second, the wall materials are made of semi-synthetic materials, mainly cellulose derivatives (such as methylcellulose and ethylcellulose), which have hydrolysis problems and are not suitable for high-temperature processing. Third, the wall materials are made of natural polymer materials. Although they have good degradability, their stability is not as good as that of synthetic polymer wall materials, especially with defects such as easy hydrolysis of the capsule wall and insufficient heat resistance.

[0005] To address the aforementioned issues, existing technologies exist that improve microcapsule performance by introducing inorganic materials or constructing composite wall material systems. For example, patent CN113441095A discloses a method for preparing silica-essential oil microcapsules. Using essential oil as the core material, a biomimetic silica mineralization method is used to prepare silica-coated essential oil microcapsules under mild conditions, improving the stability and sustained-release performance of the essential oil. Simultaneously, the silica wall material exhibits good biodegradability. However, single-layer silica wall materials still suffer from limited mechanical strength and insufficient protection of essential oils during high-temperature processing, making it difficult to meet the requirements of high-temperature chemical fiber preparation processes such as melt spinning. Furthermore, patent CN120790044A discloses a method for preparing and applying silicon-based biodegradable fragrance microcapsules. Using biodegradable polypropylene carbonate (PPC) as the wall material, a synergistic encapsulation system is constructed by introducing silicon-based mesoporous materials, utilizing a combination of physical adsorption and chemical cross-linking to achieve double-layer encapsulation of the fragrance. Although the technology achieves double-layer protection, its main wall material is PPC synthetic polymer, which is not a completely natural bio-based material, and it does not involve the application of natural polymer materials such as proteins. Therefore, its biocompatibility and complete degradability still need to be improved. Summary of the Invention

[0006] The technical problem this invention aims to solve is to overcome the shortcomings of existing high-temperature spinning processes for aromatic microcapsules, and to provide a biodegradable bio-based aromatic microcapsule with characteristics such as a wide particle size range, high encapsulation rate, good heat resistance, excellent antibacterial properties, and biodegradability. This invention also provides a method for preparing the biodegradable bio-based aromatic microcapsules, which is simple and easy to mass-produce. Applying the biodegradable bio-based aromatic microcapsules of this invention to chemical fibers improves the fragrance retention effect of the fibers, ensuring safety and long-lasting fragrance.

[0007] The method for preparing the biodegradable bio-based aromatic microcapsules of the present invention includes the following steps: (1) Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change materials and aromatic substances were mixed at a mass ratio of 1:1 to 1:3 and stirred at a temperature of 35 to 45°C and a stirring speed of 500 to 1000 r / min for 60 to 90 min to obtain a composite oily core material. Silica aerogel was then added, with a mass ratio of silica aerogel to composite oily core material of 1:2 to 1:4. Vacuum adsorption was performed, and the mixture was cooled to room temperature to obtain primary bio-based biodegradable aromatic microcapsules. (2) Preparation of the first bio-based biodegradable aromatic microcapsules The bio-based emulsifier is dissolved in water to obtain a bio-based emulsifier dispersion; the primary bio-based biodegradable aromatic microcapsules obtained in step (1) are added to the bio-based emulsifier dispersion to disperse and obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The system is dried to obtain the first bio-based biodegradable aromatic microcapsules with a particle size D90 < 10 μm. (3) Preparation of second bio-based degradable aromatic microcapsules with protein as the capsule wall The protein was added to the ionic liquid and dissolved to obtain a protein solution. Then, the first bio-based degradable aromatic microcapsule prepared in step (2) was added. The mass ratio of the first bio-based degradable aromatic microcapsule to the protein was 1:4 to 1:1. After dispersion, it was added to water to form a second bio-based degradable aromatic microcapsule dispersion. After centrifugation, it was dried to a water content ≤3.5wt.% to obtain the degradable bio-based aromatic microcapsule.

[0008] The bio-based phase change material in step (1) is one of bio-based palm oil and bio-based coconut oil; the aromatic substance is one of rose, jasmine, lemon, lemongrass, lavender, peppermint and artemisia essential oils.

[0009] The vacuum degree of the vacuum adsorption in step (1) is -90~-99kPa. After vacuum adsorption, cool to room temperature (15~25℃).

[0010] The silica aerogel in step (1) has a particle size D90 < 10 μm.

[0011] The bio-based emulsifier in step (2) is one of cashew phenol-based surfactant and sodium lignosulfonate. This step removes the complex oily components on the surface of the primary bio-based biodegradable aromatic microcapsules and improves their dispersibility in subsequent steps.

[0012] Step (2) Add to deionized water at 35~45℃ and stir at 1500~3000r / min for 20~30min.

[0013] The primary bio-based biodegradable aromatic microcapsules obtained in step (1) are added to the bio-based emulsifier dispersion, so that the mass fraction of the primary bio-based biodegradable aromatic microcapsules is 3%~6%, and the dispersion and emulsification are continued at the same rotation speed as above.

[0014] Step (2) The drying temperature is 30~37℃ and the drying time is 15h~24h.

[0015] The ionic liquid in step (3) is one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium acetate, all of which are alkylimidazolium type ionic liquids.

[0016] The protein mentioned in step (3) is one or more of soy protein isolate, collagen, silk protein and wool protein. Before use, the protein is crushed and prepared into powder with a particle size of 20~50μm to reduce the dissolution time.

[0017] Step (3) Add the protein to the ionic liquid and dissolve it for 40-80 minutes at a stirring speed of 500-650 r / min and a temperature of 85-98℃. The protein solution prepared has a protein mass fraction of 2%-3%. The obtained protein solution is preferably degassed under vacuum before use.

[0018] Step (3) After adding the first bio-based biodegradable aromatic microcapsules obtained in step (2) to the protein solution, the dispersion is slowly added to deionized water at 15-26°C at a rotation speed of 2000-2500 r / min to form the microcapsules.

[0019] Step (3) After centrifugation, vacuum dry at 30~37℃ until the moisture content is ≤3.5%.

[0020] Specifically, the preparation method of the biodegradable bio-based aromatic microcapsules includes the following steps: 1. Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change materials and aromatic substances are mixed at a mass ratio of 1:1 to 1:3 and stirred at a temperature of 35 to 45°C and a stirring speed of 500 to 1000 r / min for 60 to 90 minutes to obtain a uniformly mixed oily core material for later use.

[0021] The bio-based phase change material is one of bio-based palm oil and bio-based coconut oil; the aromatic substance is one of rose, jasmine, lemon, lemongrass, lavender, peppermint, and artemisia essential oils.

[0022] Silica aerogel (purchased from Aibiaihe New Materials Co., Ltd., particle size D90 < 10 μm) was added to a container containing the above-mentioned uniformly mixed composite oily core material. The mass ratio of silica aerogel to composite oily core material was 1:2 to 1:4. The container was then placed in a vacuum environment with a vacuum degree of -90 to -99 kPa. The composite oily core material was fully absorbed and adsorbed by the silica aerogel. The container was then cooled to 15 to 25°C to obtain primary bio-based biodegradable aromatic microcapsules with silica aerogel as the capsule wall.

[0023] 2. Preparation of the first bio-based biodegradable aromatic microcapsules A bio-based emulsifier with a mass fraction of 0.5%–1.5% was added to deionized water at a temperature of 35–45°C. The stirrer speed was adjusted to 1500–3000 r / min, and the mixture was stirred thoroughly for 20–30 min to obtain a bio-based emulsifier dispersion. Primary bio-based biodegradable aromatic microcapsules were added to the bio-based emulsifier dispersion at a mass fraction of 3%–6%, and emulsification and dispersion were continued at the same speed to obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The above dispersion was dried using a constant temperature vacuum dryer at a drying temperature of 30–37°C for 15–24 h to obtain the first bio-based biodegradable aromatic microcapsule powder with a particle size D90 < 10 μm.

[0024] The bio-based emulsifier is one of cashew phenol-based surfactant and sodium lignosulfonate. This step removes the complex oily components from the surface of the primary bio-based biodegradable aromatic microcapsules and improves their dispersibility in subsequent steps.

[0025] 3. Preparation of second bio-based biodegradable aromatic microcapsules with protein as the capsule wall 3.1 Preparation of protein solution The treated protein is added to an ionic liquid and dissolved for 40-80 minutes at a stirring speed of 500-650 r / min and a temperature of 85-98℃. The protein solution has a protein mass fraction of 2%-3%. The protein solution is then degassed under vacuum and set aside. The protein is one or more of soy protein isolate, collagen, silk protein, and wool protein. Before use, the protein is pulverized to prepare a powder with a particle size of 20-50 μm to reduce dissolution time. The ionic liquid is an alkylimidazolium type ionic liquid, preferably one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, or 1-ethyl-3-methylimidazolium acetate.

[0026] 3.2 Preparation of the second bio-based biodegradable aromatic microcapsules The prepared first bio-based biodegradable aromatic microcapsule powder and the protein solution prepared in step 3.1 were dispersed uniformly under conventional stirring at a mass ratio of 1:4 to 1:1 of the effective components to obtain a first bio-based biodegradable aromatic microcapsule powder / protein dispersion. Then, this dispersion was slowly added to deionized water at 15-26°C at a speed of 2000-2500 r / min to form a second bio-based biodegradable aromatic microcapsule dispersion. The second bio-based biodegradable aromatic microcapsule dispersion was centrifuged to obtain a wet second bio-based biodegradable aromatic microcapsule powder, which was then dried in a constant temperature vacuum dryer at 30-37°C until the moisture content was ≤3.5%, thus obtaining the second bio-based biodegradable aromatic microcapsule powder, which is the bio-based biodegradable aromatic microcapsule powder of this invention.

[0027] The biodegradable bio-based aromatic microcapsules have a particle size D90 of 1.567~9.265μm.

[0028] 4. The application of the biodegradable bio-based aromatic microcapsules includes the following steps: melt spinning or wet spinning the biodegradable bio-based aromatic microcapsules with fiber-forming raw materials to obtain nascent fibers, and then plasma treating the nascent fibers to obtain aromatic chemical fibers.

[0029] The mass ratio of the fiber-forming raw material to the biodegradable bio-based aromatic microcapsules is 100:10~30; the output power of the plasma treatment is 160W~260W, the treatment time is 60~90s, the reaction gas is air, and the reaction pressure is 60~90Pa. After plasma treatment, the surface structure of the fiber is etched, the surface area is increased, and the fiber functionality is facilitated.

[0030] 4.1 The melt spinning process is as follows: First, the fiber-forming polymer and the biodegradable bio-based aromatic microcapsules are dried to a moisture content below 500 ppm. Then, they are mixed at a mass ratio of 100:10~30 and added to a single-screw extruder for granulation to obtain fiber-forming polymer chips with aromatic functions. The fiber-forming polymer is a fiber that can be melt-spun, preferably one of polylactic acid fiber, polypropylene fiber, or polyamide fiber. The temperature of the single-screw extruder is the melting temperature of the fiber-forming polymer, and the melting temperature varies depending on the fiber-forming polymer used. The bio-based biodegradable aromatic microcapsule powder used is preferably with a particle size D90 ≤ 2.8 μm. The screw speed of the single-screw extruder is 100~120 r / min, and the vacuum degree is -0.05~-0.1 MPa. The obtained fiber-forming polymer chips with aromatic functions are spun using a twin-screw extruder, and the spinning temperature is adjusted according to the different fiber-forming polymers. The spinning speed is 1000~1200m / min, the draw ratio is 1.8~3.2 times, and the spinneret can be round, flat, cross-shaped orifice. The filament bundle is cooled by air at 20~35℃ or by ring blowing to obtain nascent fibers with soothing function. The nascent fibers are made into filaments by known fiber processing processes such as drawing, setting, crimping or twisting, or further processed into aromatic functional short fibers.

[0031] 4.2 The wet spinning process is as follows: a wet spinning polymer solution and a dispersion of biodegradable bio-based aromatic microcapsules are mixed evenly at an effective component mass ratio of 100:10~30, then spun using a wet spinning process, and refined through conventional and well-known refining methods to obtain wet-spun chemical fibers. The wet spinning polymer includes one of viscose fiber, lyocell fiber, or polyacrylonitrile fiber; the effective component of the dispersion of the biodegradable bio-based aromatic microcapsules has a particle size D90 ≤ 2.8 μm.

[0032] 4.3 Plasma Treatment: The obtained nascent fibers are subjected to plasma treatment to etch the surface structure of the fibers, increasing the surface area and facilitating the functional performance of the fibers during use, thereby improving their performance. The specific conditions for plasma etching are as follows: the output power of the plasma treatment is 160W~260W, the treatment time is 60~90s, the reaction gas is air, and the reaction pressure is 60~90Pa. After plasma treatment, the surface structure of the fibers is etched, the surface area is increased, and the functionality of the fibers is facilitated.

[0033] Compared with the prior art, the beneficial effects of the present invention are: (1) The bio-based biodegradable aromatic microcapsule powder prepared by the present invention protects the aromatic substances through a variety of means: the bio-based phase change material can buffer the temperature through the phase change process when the ambient temperature changes, so that the aromatic substances do not have large temperature fluctuations, thus further protecting the aromatic substances; through the double capsule wall method, the adsorption effect of the silica aerogel of the first capsule wall and the coating effect of the protein of the second capsule wall are utilized, and the good heat insulation effect of the silica aerogel is used to avoid the destruction of the aromatic substances by the microcapsule in the subsequent high temperature process; in the microcapsule preparation process, the influence of high temperature on the aromatic substances is avoided by reducing the temperature and extending the time.

[0034] (2) The phase change material and emulsifier used in this invention are bio-based materials, which are natural, harmless, low-carbon and environmentally friendly. At the same time, the ionic liquid used to dissolve proteins is non-toxic, safe and recyclable, so that the prepared bio-based biodegradable aromatic microcapsules have both functionality and ecological safety.

[0035] (3) The double capsule walls of the present invention are respectively made of silica aerogel and protein, and the aromatic substances in the capsule core are made of plant essential oils. All of them have natural properties, are harmless to the natural environment, and can be naturally degraded. The health-care properties and multi-reactive group characteristics of protein can improve the safety during application and facilitate functional modification and application.

[0036] (4) The bio-based biodegradable aromatic microcapsules prepared by the present invention have a spherical structure with a particle size of 1.567~9.265μm; improved heat resistance with an initial thermal decomposition temperature ≥175.5℃; inhibition rate against Staphylococcus aureus ≥96.1%, inhibition rate against Escherichia coli ≥95.8%, and inhibition rate against Candida albicans ≥95.2%; after being released at room temperature for 30 days, the residual rate of aromatic substances in the bio-based biodegradable aromatic microcapsule powder is ≥85.1%; and the degradation rate is ≥75%.

[0037] (5) The aromatic functional chemical fiber prepared by the present invention has good antibacterial and aromatic functions, with an inhibition rate of ≥81.8% against Escherichia coli, ≥82.3% against Staphylococcus aureus, and ≥80.6% against Candida albicans; the aroma retention time of the aromatic functional chemical fiber is ≤16.5% after 30 days; after 20 water washes, the aroma content of the aromatic functional chemical fiber is ≥19.6%. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments.

[0039] The detection of the microcapsules or fibers of the present invention shall be carried out in accordance with the following standards: (1) Antibacterial performance test of fibers: Escherichia coli, Staphylococcus aureus, Candida albicans, GB / T20944.3-2008 Evaluation of antibacterial properties of textiles Part 3: Vibration method; (2) Fragrance retention time of fibers, expressed as the loss rate of aromatic substances after 30 days: Aromatic functional chemical fibers are made into 5cm×10cm non-woven fabrics. Under constant temperature and humidity, they are placed in a sealed container for 30 minutes to ensure that the fragrance fills the entire container. Then, the VOC gas detector probe is placed in the container, and the value after the instrument stabilizes is read. This is the fragrance concentration released by the aromatic functional chemical fiber non-woven fabric in the container of that volume. Then, the non-woven fabric is taken out and placed in an open bottle under environmental conditions. Then, the test is carried out at the same time every day to obtain the fragrance retention effect of the aromatic functional chemical fiber non-woven fabric under natural placement. Each sample is tested 3 times. (3) Aromatic content of fibers after 20 washes: The washing method adopted is the washing conditions and procedures in GB / T 8629-2017 "Home washing and drying procedures for textile testing".

[0040] (4) Particle size of microcapsules: tested using a Bettersize2600 laser particle size analyzer; (5) Heat resistance of microcapsules: The temperature was raised from 50℃ to 600℃ using a thermogravimetric analyzer at a heating rate of 10℃ / min, with nitrogen gas as a protective gas during the heating process and a nitrogen gas flow rate of 20mL / min. The heat resistance stability of the microcapsules was tested.

[0041] (6) The residual rate of aromatic substances in bio-based degradable aromatic microcapsule powder after 30 days of release at room temperature: The maximum absorption wavelength of the aromatic substances and its standard working curve were measured by ultraviolet spectrophotometer and then calculated. (7) Degradability (biodegradation rate) of microcapsules: The biodegradation rate test is based on GB / T19277.1-2011 "Determination of final aerobic biodegradation capacity of materials under controlled composting conditions by means of determination of released carbon dioxide - Part 1: General method". Example 1

[0042] The method for preparing the biodegradable bio-based aromatic microcapsules of the present invention includes the following steps: 1. Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change material and aromatic substances were mixed at a mass ratio of 1:1 at 35℃ and a stirring speed of 500 r / min for 90 min to obtain a uniformly mixed oily core material for later use.

[0043] The bio-based phase change material is bio-based palm oil; the aromatic substance is rose essential oil.

[0044] Silica aerogel (purchased from Aibiaihe New Materials Co., Ltd., particle size D90 < 10 μm) was added to a container containing the above-mentioned uniformly mixed composite oily core material. The mass ratio of silica aerogel to composite oily core material was 1:2. The container was then placed in a vacuum environment with a vacuum degree of -90 kPa. The composite oily core material was fully absorbed and adsorbed by the silica aerogel. The container was then cooled to 15°C to obtain primary bio-based biodegradable aromatic microcapsules with silica aerogel as the capsule wall.

[0045] 2. Preparation of the first bio-based biodegradable aromatic microcapsules A bio-based emulsifier with a mass fraction of 0.5% was added to deionized water at 35°C, and the stirrer speed was adjusted to 3000 r / min. The mixture was stirred thoroughly for 20 min to obtain a bio-based emulsifier dispersion. Primary bio-based biodegradable aromatic microcapsules were added to the bio-based emulsifier dispersion at a mass fraction of 3%, and emulsification and dispersion continued at the same speed to obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The above dispersion was dried using a constant temperature vacuum dryer at 30°C for 24 h to obtain the first bio-based biodegradable aromatic microcapsule powder. The bio-based emulsifier was a cashew nut shell surfactant.

[0046] 3. Preparation of second bio-based biodegradable aromatic microcapsules with protein as the capsule wall 3.1 Preparation of protein solution The treated protein was added to an ionic liquid and dissolved for 80 minutes at a stirring speed of 500 rpm and a temperature of 85°C. The resulting protein solution contained 3% protein by mass. The protein solution was then degassed under vacuum and set aside for use. The protein was soy protein isolate, which was pulverized to a particle size of 20 μm before use to reduce dissolution time. The ionic liquid used was 1-allyl-3-methylimidazolium chloride.

[0047] 3.2 Preparation of the second bio-based biodegradable aromatic microcapsules The prepared first bio-based biodegradable aromatic microcapsule powder and the protein solution prepared in step 3.1 were dispersed uniformly under conventional stirring at a mass ratio of 1:4 for the effective components to obtain a first bio-based biodegradable aromatic microcapsule powder / protein dispersion. This dispersion was then slowly added to deionized water at 15°C at a rotation speed of 2000 r / min to form a second bio-based biodegradable aromatic microcapsule dispersion. The second bio-based biodegradable aromatic microcapsule dispersion was centrifuged to obtain a wet second bio-based biodegradable aromatic microcapsule powder, which was then dried in a constant temperature vacuum dryer at 30°C until the moisture content reached 3.5%, thus obtaining the second bio-based biodegradable aromatic microcapsule powder, which is the bio-based biodegradable aromatic microcapsule powder of this invention.

[0048] The bio-based biodegradable aromatic microcapsules prepared by this invention have a particle size D90 of 1.567 μm; heat resistance: initial thermal decomposition temperature 175.5℃; inhibition rate against Staphylococcus aureus 96.1%, against Escherichia coli 95.8%, and against Candida albicans 95.2%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based biodegradable aromatic microcapsule powder is 85.1%; and the degradation rate (biodegradation rate) is 75%.

[0049] 4. Preparation of Aromatic Functional Chemical Fibers - Melt Spinning Method for Preparing Aromatic Functional Chemical Fibers The fiber-forming polymer and bio-based biodegradable aromatic microcapsule powder were dried to a moisture content below 500 ppm, then mixed at a mass ratio of 100:10 and granulated in a single-screw extruder to obtain aromatic fiber-forming polymer chips. The fiber-forming polymer was polypropylene; the temperature of the single-screw extruder was 145°C. The preferred particle size of the prepared bio-based biodegradable aromatic microcapsule powder was D90 = 1.567 μm; the screw speed of the single-screw extruder was 100 r / min, and the vacuum degree was -0.05 MPa.

[0050] The obtained aromatic fiber-forming polymer chips were spun using a twin-screw extruder at a spinning temperature of 145℃. The spinning speed was 1000 m / min, the draw ratio was 1.8, and a circular spinneret was used. The fiber bundle was cooled using 35℃ air and a ring blower to obtain nascent fibers with soothing properties. The nascent fibers were then processed into polypropylene filaments using known fiber treatment processes such as drawing, setting, crimping, or twisting.

[0051] Plasma treatment of aromatic functional chemical fibers: The prepared melt-spun aromatic functional chemical fibers are subjected to plasma treatment to improve their performance. The specific plasma etching conditions are as follows: the output power of the plasma treatment is 160W, the reaction time is 90s, the reaction gas is air, and the reaction pressure is 60Pa.

[0052] The prepared aromatic functional chemical fiber has good antibacterial, aromatic functions and wash resistance. The inhibition rate of Escherichia coli is 81.8%, the inhibition rate of Staphylococcus aureus is 82.3%, and the inhibition rate of Candida albicans is 80.6%. The fragrance retention time of the aromatic functional chemical fiber is 12.3% after 30 days. After 20 washes, the aromatic content of the aromatic functional chemical fiber is 23.2%. Example 2

[0053] The method for preparing the biodegradable bio-based aromatic microcapsules of the present invention includes the following steps: 1. Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change material and aromatic substances were mixed at a mass ratio of 1:2 and stirred at 40℃ and 760r / min for 82min to obtain a uniformly mixed oily core material for later use.

[0054] The bio-based phase change material is bio-based coconut oil; the aromatic substance is lavender essential oil.

[0055] Silica aerogel (purchased from Aibiaihe New Materials Co., Ltd., particle size D90 < 10 μm) was added to a container containing the above-mentioned uniformly mixed composite oily core material. The mass ratio of silica aerogel to composite oily core material was 1:3. The container was then placed in a vacuum environment with a vacuum degree of -95 kPa. The composite oily core material was fully absorbed and adsorbed by the silica aerogel. The container was then cooled to 20°C to obtain primary bio-based biodegradable aromatic microcapsules with silica aerogel as the capsule wall.

[0056] 2. Preparation of the first bio-based biodegradable aromatic microcapsules A 1.0% (w / w) bio-based emulsifier was added to deionized water at 40°C, and the stirrer speed was adjusted to 2300 r / min. The mixture was stirred thoroughly for 25 min to obtain a bio-based emulsifier dispersion. Primary bio-based biodegradable aromatic microcapsules were added to the bio-based emulsifier dispersion at a 4.5% (w / w) ratio, and emulsification and dispersion continued at the same speed to obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The dispersion was dried using a constant-temperature vacuum dryer at 33°C for 20 h to obtain the first bio-based biodegradable aromatic microcapsule powder. The bio-based emulsifier was sodium lignosulfonate.

[0057] 3. Preparation of second bio-based biodegradable aromatic microcapsules with protein as the capsule wall 3.1 Preparation of protein solution The treated protein was added to an ionic liquid and dissolved for 60 minutes at a stirring speed of 580 r / min and a temperature of 92℃. The resulting protein solution contained 2.5% protein by mass. The protein solution was then degassed under vacuum and set aside for use. The protein was collagen, which was pulverized into powder with a particle size of 35 μm before use to reduce dissolution time. The ionic liquid used was 1-butyl-3-methylimidazolium chloride.

[0058] 3.2 Preparation of the second bio-based biodegradable aromatic microcapsules The prepared first bio-based biodegradable aromatic microcapsule powder and the protein solution prepared in step 3.1 were dispersed uniformly under conventional stirring at a mass ratio of 1:2.5 of the effective components to obtain a first bio-based biodegradable aromatic microcapsule powder / protein dispersion. Then, this dispersion was slowly added to deionized water at 20°C at a rotation speed of 2300 r / min to form a second bio-based biodegradable aromatic microcapsule dispersion. The second bio-based biodegradable aromatic microcapsule dispersion was centrifuged to obtain a wet second bio-based biodegradable aromatic microcapsule powder, which was then dried in a constant temperature vacuum dryer at 34°C until the moisture content reached 2.9%, thus obtaining the second bio-based biodegradable aromatic microcapsule powder, which is the bio-based biodegradable aromatic microcapsule powder of this invention.

[0059] The bio-based biodegradable aromatic microcapsules prepared by this invention have a particle size D90 = 1.962 μm; heat resistance: initial thermal decomposition temperature 180.9℃; inhibition rate against Staphylococcus aureus 98.3%, against Escherichia coli 97.1%, and against Candida albicans 96.9%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based biodegradable aromatic microcapsule powder is 87.2%; and the degradation rate (biodegradation rate) is 78.5%.

[0060] 4. Preparation of Aromatic Functional Chemical Fibers - Preparation of Aromatic Functional Chemical Fibers by Wet Spinning Method The wet-spun polymer solution and the second bio-based biodegradable aromatic microcapsule dispersion prepared in step 3.2 were mixed evenly at a mass ratio of 100:20 for the effective components. The mixture was then spun using a wet process and refined through conventional and well-known refining methods to obtain wet-spun chemical fibers. The wet-spun polymer is viscose fiber; the effective component of the second bio-based biodegradable aromatic microcapsule dispersion has a particle size D90 = 1.962 μm.

[0061] Plasma treatment of aromatic functional chemical fibers: The prepared melt-spun or wet-spun aromatic functional chemical fibers are subjected to plasma treatment to improve their performance. The specific plasma etching conditions are as follows: the output power of the plasma treatment is 210W, the reaction time is 75s, the reaction gas is air, and the reaction pressure is 75Pa.

[0062] The prepared aromatic functional chemical fiber has good antibacterial, aromatic functions and wash resistance. It has an inhibition rate of 85.9% against Escherichia coli, 84.9% against Staphylococcus aureus, and 82.5% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber is 15.1% after 30 days. After 20 washes, the aromatic content of the aromatic functional chemical fiber is 20.5%. Example 3

[0063] The method for preparing the biodegradable bio-based aromatic microcapsules of the present invention includes the following steps: 1. Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change material and aromatic substances were mixed at a mass ratio of 1:3 and stirred at 45℃ and 1000 r / min for 60 min to obtain a uniformly mixed oily core material for later use.

[0064] The bio-based phase change material is bio-based palm oil; the aromatic substance is artemisia oil.

[0065] Silica aerogel (purchased from Aibiaihe New Materials Co., Ltd., particle size D90 < 10 μm) was added to a container containing the above-mentioned uniformly mixed composite oily core material. The mass ratio of silica aerogel to composite oily core material was 1:4. The container was then placed in a vacuum environment with a vacuum degree of -99 kPa. The composite oily core material was fully absorbed and adsorbed by the silica aerogel. The container was then cooled to 25°C to obtain primary bio-based biodegradable aromatic microcapsules with silica aerogel as the capsule wall.

[0066] 2. Preparation of the first bio-based biodegradable aromatic microcapsules A 1.5% (w / w) bio-based emulsifier was added to deionized water at 45°C, and the stirrer speed was adjusted to 1500 r / min. The mixture was stirred thoroughly for 30 min to obtain a bio-based emulsifier dispersion. Primary bio-based biodegradable aromatic microcapsules were added to the bio-based emulsifier dispersion at a 6% (w / w) ratio, and emulsification and dispersion continued at the same speed to obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The dispersion was dried using a constant-temperature vacuum dryer at 37°C for 15 h to obtain the first bio-based biodegradable aromatic microcapsule powder. The bio-based emulsifier was a cashew nut shell surfactant.

[0067] 3. Preparation of second bio-based biodegradable aromatic microcapsules with protein as the capsule wall 3.1 Preparation of protein solution The treated protein was added to an ionic liquid and dissolved for 40 minutes at a stirring speed of 650 r / min and a temperature of 98℃. The resulting protein solution contained 2% protein by mass. The protein solution was then degassed under vacuum and set aside for use. The protein was wool protein, which was pulverized to a particle size of 35 μm before use to reduce dissolution time. The ionic liquid used was 1-ethyl-3-methylimidazolium acetate.

[0068] 3.2 Preparation of the second bio-based biodegradable aromatic microcapsules The prepared first bio-based biodegradable aromatic microcapsule powder and the protein solution prepared in step 3.1 were dispersed uniformly under conventional stirring at a mass ratio of 1:1 for the effective components to obtain a first bio-based biodegradable aromatic microcapsule powder / protein dispersion. This dispersion was then slowly added to deionized water at 26°C at a rotation speed of 2500 r / min to form a second bio-based biodegradable aromatic microcapsule dispersion. The second bio-based biodegradable aromatic microcapsule dispersion was centrifuged to obtain a wet second bio-based biodegradable aromatic microcapsule powder, which was then dried in a constant-temperature vacuum dryer at 37°C until the moisture content reached 2.0%, thus obtaining the second bio-based biodegradable aromatic microcapsule powder, which is the bio-based biodegradable aromatic microcapsule powder of this invention.

[0069] The bio-based biodegradable aromatic microcapsules prepared by this invention have a particle size D90 = 2.158 μm; heat resistance: initial thermal decomposition temperature 195.3℃; inhibition rate against Staphylococcus aureus 99.2%, against Escherichia coli 98.9%, and against Candida albicans 98.5%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based biodegradable aromatic microcapsule powder is 90.6%; and the degradation rate (biodegradation rate) is 81.6%.

[0070] 4. Preparation of Aromatic Functional Chemical Fibers - Preparation of Aromatic Functional Chemical Fibers by Wet Spinning Method The wet-spinning polymer solution and the second bio-based biodegradable aromatic microcapsule dispersion prepared in step 3.2 were mixed evenly at a mass ratio of 100:30 for the effective components. The mixture was then spun using a wet process and refined through conventional and well-known refining methods to obtain wet-spinned chemical fibers. The wet-spinning polymer was polyacrylonitrile fiber; the effective component of the second bio-based biodegradable aromatic microcapsule dispersion had a particle size D90 = 2.158 μm.

[0071] Plasma treatment of aromatic functional chemical fibers: The prepared melt-spun or wet-spun aromatic functional chemical fibers are subjected to plasma treatment to improve their performance. The specific plasma etching conditions are as follows: the output power of the plasma treatment is 260W, the reaction time is 60s, the reaction gas is air, and the reaction pressure is 90Pa.

[0072] The prepared aromatic functional chemical fiber has good antibacterial, aromatic functions and wash resistance. It has an inhibition rate of 87.3% against Escherichia coli, 86.7% against Staphylococcus aureus, and 84.9% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber is 16.5% after 30 days. After 20 washes, the aromatic content of the aromatic functional chemical fiber is 19.6%.

[0073] Comparative Example 1 The difference between this comparative example and Example 1 (rose essential oil / palm oil / silica aerogel / soy protein) is that: in step (1), no bio-based phase change material (bio-based palm oil) is added, and the aromatic substance (rose essential oil) is directly vacuum adsorbed with silica aerogel.

[0074] The specific modifications are as follows: Step (1): The aromatic substance (rose essential oil) was used alone as the oily core material. The silica aerogel and rose essential oil were mixed at a mass ratio of 1:2, stirred at 35°C and 500 r / min for 60 min, and adsorbed under a vacuum of -90 kPa. The primary microcapsules were then obtained by cooling. The remaining steps were the same as in Example 1.

[0075] The prepared microcapsules had a particle size D90 of 1.552 μm; heat resistance: initial thermal decomposition temperature 165.1℃; inhibition rate against Staphylococcus aureus 95.8%, against Escherichia coli 95.3%, and against Candida albicans 94.9%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based degradable aromatic microcapsule powder was 80.2%; the degradation rate (biodegradation rate) was 71.5%.

[0076] The prepared chemical fiber showed an inhibition rate of 80.9% against Escherichia coli, 81.5% against Staphylococcus aureus, and 80.0% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber was 13.2% after 30 days. After 20 washes, the fragrance content of the aromatic functional chemical fiber was 21.3%.

[0077] As shown in Comparative Example 1, the absence of bio-based phase change material (bio-based palm oil) reduces the heat resistance of the microcapsules. After 30 days of release at room temperature, the residual rate and degradation rate (biodegradation rate) of the aromatic substances in the bio-based biodegradable aromatic microcapsule powder decrease. The aromatic substance loss rate of the prepared chemical fibers increases after 30 days, and the aromatic substance content of the aromatic functional chemical fibers decreases after 20 washes. Other functions remain largely unchanged.

[0078] Comparative Example 2 The difference between this comparative example and Example 2 (lavender essential oil / coconut oil / silica aerogel / collagen) is that: in step (1), silica aerogel is not added, and the composite oily core material of bio-based phase change material and aromatic substances is directly emulsified.

[0079] The specific modifications are as follows: Step (1) is omitted. Bio-based coconut oil and lavender essential oil are directly mixed at a mass ratio of 1:2 at 40°C to form a composite oily core material. Then, in step (2), it is added to sodium lignosulfonate dispersion at a mass fraction of 4.5% for emulsification and dispersion, and dried to obtain the first microcapsule (silica-free aerogel). Step (3) is the same as in Example 2, with collagen coating.

[0080] The prepared microcapsules had a particle size D90 of 1.902 μm; heat resistance: initial thermal decomposition temperature 169.8℃; inhibition rate against Staphylococcus aureus 97.2%, against Escherichia coli 96.5%, and against Candida albicans 95.9%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based degradable aromatic microcapsule powder was 79.2%; the degradation rate (biodegradation rate) was 75.6%.

[0081] The prepared chemical fiber showed an inhibition rate of 84.8% against Escherichia coli, 83.6% against Staphylococcus aureus, and 81.9% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber was 16.2% after 30 days. After 20 washes, the fragrance content of the aromatic functional chemical fiber was 16.9%.

[0082] Comparative Example 2 shows that the absence of silica aerogel reduces the microcapsule particle size and heat resistance. After 30 days of release at room temperature, the residual rate and degradation rate (biodegradation rate) of the aromatic substances in the bio-based degradable aromatic microcapsule powder decrease. The aromatic substance loss rate of the prepared chemical fibers increases after 30 days, and the aromatic substance content of the aromatic functional chemical fibers decreases after 20 washes. Other functions remain largely unchanged.

[0083] Comparative Example 3 The difference between this comparative example and Example 3 (Artemisia argyi essential oil / palm oil / silica aerogel / wool protein) is that protein coating is not used in step (3), that is, after the first bio-based biodegradable aromatic microcapsule is prepared, it is directly used as the final product.

[0084] The specific modifications are as follows: Only steps (1) and (2) are completed to obtain the first bio-based biodegradable aromatic microcapsule powder (based on silica aerogel / artemisia oil / palm oil), and the protein solution coating in step (3) is not performed. The remaining parameters are the same as in Example 3.

[0085] The prepared microcapsules had a particle size D90 of 2.075 μm; heat resistance: initial thermal decomposition temperature 183.8℃; inhibition rate against Staphylococcus aureus 99.3%, against Escherichia coli 98.6%, and against Candida albicans 98.7%; after 30 days of release at room temperature, the residual rate of aromatic substances in the bio-based degradable aromatic microcapsule powder was 85.3%; the degradation rate (biodegradation rate) was 78.1%.

[0086] The prepared chemical fiber showed an inhibition rate of 87.5% against Escherichia coli, 86.9% against Staphylococcus aureus, and 85.0% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber was 19.6% after 30 days. After 20 washes, the fragrance content of the aromatic functional chemical fiber was 15.9%.

[0087] Comparative Example 3 shows that by not using protein coating, the microcapsule particle size is reduced, and after 30 days of release at room temperature, the residual rate and degradation rate (biodegradation rate) of aromatic substances in the bio-based degradable aromatic microcapsule powder decrease. The aromatic substance loss rate of the prepared chemical fibers increases after 30 days, and after 20 washes, the aromatic substance content of the aromatic functional chemical fibers decreases. Other functions remain essentially unchanged.

[0088] Comparative Example 4 The difference between this comparative example and Example 1 (polypropylene fiber) is that the nascent fiber is not subjected to plasma treatment in step 4, while the rest of the spinning process is exactly the same.

[0089] The specific modifications are as follows: After polypropylene fibers were prepared by melt spinning according to Example 1, no plasma treatment was performed.

[0090] The prepared chemical fiber showed an inhibition rate of 75.6% against Escherichia coli, 75.2% against Staphylococcus aureus, and 73.7% against Candida albicans. The fragrance retention time of the aromatic functional chemical fiber was 11.9% after 30 days. After 20 washes, the fragrance content of the aromatic functional chemical fiber was 24.2%.

[0091] As can be seen from Comparative Example 4, after polypropylene fibers are obtained by melt spinning, the antibacterial properties of the prepared chemical fibers decrease significantly without any plasma treatment, while the other properties remain largely unchanged.

Claims

1. A method for preparing biodegradable bio-based aromatic microcapsules, characterized in that, Includes the following steps: (1) Preparation of primary bio-based biodegradable aromatic microcapsules Bio-based phase change materials and aromatic substances were mixed at a mass ratio of 1:1 to 1:3 and stirred at a temperature of 35 to 45°C and a stirring speed of 500 to 1000 r / min for 60 to 90 min to obtain a composite oily core material. Silica aerogel was then added, with a mass ratio of silica aerogel to composite oily core material of 1:2 to 1:

4. Vacuum adsorption was performed, and the mixture was cooled to room temperature to obtain primary bio-based biodegradable aromatic microcapsules. (2) Preparation of the first bio-based biodegradable aromatic microcapsules The bio-based emulsifier is dissolved in water to obtain a bio-based emulsifier dispersion; the primary bio-based biodegradable aromatic microcapsules obtained in step (1) are added to the bio-based emulsifier dispersion to disperse and obtain a primary bio-based biodegradable aromatic microcapsule dispersion system. The system is dried to obtain the first bio-based biodegradable aromatic microcapsules with a particle size D90 < 10 μm. (3) Preparation of second bio-based degradable aromatic microcapsules with protein as the capsule wall The protein was added to the ionic liquid and dissolved to obtain a protein solution. Then, the first bio-based degradable aromatic microcapsule prepared in step (2) was added. The mass ratio of the first bio-based degradable aromatic microcapsule to the protein was 1:4 to 1:

1. After dispersion, it was added to water to form a second bio-based degradable aromatic microcapsule dispersion. After centrifugation, it was dried to a water content ≤3.5wt.% to obtain the degradable bio-based aromatic microcapsule.

2. The method for preparing biodegradable biobased aromatic microcapsules according to claim 1, characterized in that, The bio-based phase change material in step (1) is one of bio-based palm oil and bio-based coconut oil; the aromatic substance is one of rose, jasmine, lemon, lemongrass, lavender, peppermint and artemisia essential oils.

3. The method for preparing biodegradable biobased aromatic microcapsules according to claim 2, characterized in that, The vacuum degree of vacuum adsorption in step (1) is -90~-99kPa.

4. The method for preparing biodegradable bio-based aromatic microcapsules according to claim 1, characterized in that, The bio-based emulsifier mentioned in step (2) is one of cashew phenol-based surfactant and sodium lignin sulfonate.

5. The method for preparing biodegradable biobased aromatic microcapsules according to claim 4, characterized in that, Step (2) The drying temperature is 30~37℃ and the drying time is 15h~24h.

6. The method for preparing biodegradable biobased aromatic microcapsules according to claim 1, characterized in that, The ionic liquid in step (3) is one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium acetate.

7. The method for preparing biodegradable biobased aromatic microcapsules according to claim 6, characterized in that, The protein mentioned in step (3) is one or more of soy protein isolate, collagen, silk protein and wool protein. Before use, the protein is crushed and prepared into powder with a particle size of 20~50μm.

8. A biodegradable biobased aromatic microcapsule, characterized in that, It is prepared by the method of preparing biodegradable bio-based aromatic microcapsules according to any one of claims 1-7, wherein the particle size D90 of the microcapsules is 1.567~9.265μm.

9. An application of the biodegradable biobased aromatic microcapsule according to claim 8, characterized in that, Includes the following steps: The biodegradable bio-based aromatic microcapsules are melt-spun or wet-spun with fiber-forming raw materials to obtain nascent fibers. Then, the nascent fibers are subjected to plasma treatment to obtain aromatic chemical fibers.

10. The application of the biodegradable biobased aromatic microcapsules according to claim 9, characterized in that, The mass ratio of fiber-forming raw materials to biodegradable bio-based aromatic microcapsules is 100:10~30; the output power of plasma treatment is 160W~260W, the treatment time is 60~90s, the reaction gas is air, and the reaction pressure is 60~90Pa.