High enthalpy phase-change temperature-regulating lyocell fiber and preparation method thereof

Abstract

The present invention belongs to the technical field of lyocell fibers, and specifically relates to high-enthalpy phase-change temperature-regulating lyocell fibers and a preparation method thereof. The preparation method of the high-enthalpy phase-change temperature-regulating lyocell fibers comprises the following steps: using a mixture of n-octadecane, n-nonadecane, and n-heneicosane as a capsule core material, polyurethane as an inner capsule wall, and a product of gelatin and gum arabic as an outer capsule wall to prepare phase-change temperature-regulating microcapsules; adding cellulose pulp to a cellulose solvent to prepare a cellulose spinning solution; adding phase-change temperature-regulating microcapsules to an aqueous solution of a low-concentration cellulose solvent to prepare a phase-change temperature-regulating microcapsule dispersion system; and mixing the cellulose spinning solution and the phase-change temperature-regulating microcapsule dispersion system to prepare high-enthalpy phase-change temperature-regulating lyocell fibers. The high-enthalpy phase-change temperature-regulating lyocell fibers prepared by the present invention have good dispersibility and compatibility of the phase-change temperature-regulating microcapsules contained therein in the fibers, and have good phase-change temperature-regulating function and toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of lyocell fibers, and particularly relates to high-enthalpy phase-change temperature-regulating lyocell fibers and a preparation method thereof. Background Art

[0002] Regenerated cellulose fiber is made from natural cellulose by modifying only its physical structure without changing its chemical structure. Regenerated cellulose fiber retains the advantages of natural fibers while also adding greater functionality through innovative production technologies, making it a promising alternative to natural fibers. Lyocell fiber, among others, is produced through a dry-jet wet spinning process using N-methylmorpholine-N-oxide (NMMO) as a direct solvent for cellulose. Compared to viscose fiber, Lyocell fiber boasts a simpler, more environmentally friendly production process, superior performance, and strong market competitiveness and promising development prospects.

[0003] Phase-change thermoregulating fiber is a heat-storage thermoregulating fiber developed by exploiting the property of materials releasing or absorbing latent heat while maintaining a constant temperature during phase change. It exhibits bidirectional automatic thermoregulation and acts as a temperature buffer when used in clothing, minimizing skin temperature fluctuations and prolonging the wearer's comfort. Therefore, the preparation of phase-change thermoregulating cellulose fibers based on Lyocell fibers has become a hot topic in functional regenerated cellulose fiber research. Currently, the most commonly used methods for preparing phase-change thermoregulating Lyocell fibers are blending and microencapsulation.

[0004] Among them, the blending method is to directly blend the phase change material and the polymer for spinning. This method has problems such as low phase change thermal enthalpy, easy phase change leakage and low fiber strength.

[0005] For example, the method for preparing thermoregulating fibers disclosed in patent CN110886026A involves adding a mixture of semi-refined paraffin waxes directly to the spinning slurry of lyocell fibers as a phase change material. During the preparation process, the temperature of some bath solutions is much higher than the melting point of the phase change material, which can lead to a significant loss of the phase change material, affecting the functionality of the fiber and the recovery of NMMO. The method for preparing lyocell fibers with phase change and thermoregulating properties disclosed in patent CN117166076A uses n-dodecane, which has a relatively high melting point (37.8°C), as a phase change material and adds it to the NMMO solution to prepare the spinning solution. This reduces the amount of phase change material lost during the preparation process. However, n-dodecane has a high phase change crystallization temperature and has a limited buffering effect on temperature.

[0006] The microencapsulation method is to encapsulate the phase change material in microcapsules, coat the fabric or mix the microcapsules into the spinning solution for spinning. The phase change fiber made by this method has the advantage that the phase change material is evenly dispersed and will not escape.

[0007] For example, the high enthalpy phase change temperature regulating lyocell fiber disclosed in patent CN113604896A is made of lyocell fiber and phase change temperature regulating microcapsules cross-linked with lyocell fiber, wherein the phase change temperature regulating microcapsules include capsule walls and capsule cores, the capsule cores include phase change material and nano nucleating agent, and the capsule walls include melamine modified urea-formaldehyde resin prepolymers. This invention utilizes microcapsules to reduce the loss of phase change material, but it uses formaldehyde and glutaraldehyde when preparing microcapsules, which easily causes the formaldehyde content in the fiber to exceed the standard, limiting its application. Patent CN116121893A discloses a microcapsule phase change lyocell fiber and a preparation method thereof. The microcapsule phase change emulsion used in this invention includes molten phase change material, carbon nanotubes, emulsifier and resin. It mainly improves the thermal conductivity of the phase change material by adding carbon nanotubes, but the introduction of carbon nanotubes can give the fiber a black attribute, causing the application of the fiber to be limited. Similarly, the preparation method for heat-storage and temperature-regulating Lyocell fibers disclosed in patent CN119308031A improves the fiber's heat absorption and temperature-regulating properties by introducing graphene oxide and phase-change microcapsules. However, the introduction of graphene oxide also imparts a black color to the fiber, limiting its application. Furthermore, the aforementioned patents utilize single-layer polyurethane-walled microcapsules. This single-layer wall provides limited protection for the core during the fiber spinning process, potentially damaging some microcapsules. Furthermore, the microcapsules' spherical structure can affect the fiber's toughness and reduce its strength.

[0008] Therefore, how to protect the phase change temperature regulating microcapsules from damage during the fiber spinning process without causing a decrease in fiber strength is a technical problem that needs to be solved urgently. Summary of the Invention

[0009] In response to the problems existing in the prior art, the purpose of the present invention is to provide a high-enthalpy phase-change temperature-regulating lyocell fiber, the phase-change temperature-regulating microcapsules contained in the fiber have good dispersibility and compatibility in the fiber, do not affect the fiber's own color, and have good phase-change temperature-regulating, antibacterial and ammonia removal functions; the present invention also provides a preparation method thereof, which is feasible and convenient for mass production.

[0010] The method for preparing the high enthalpy phase-change temperature-regulating lyocell fiber of the present invention comprises the following steps:

[0011] (1) Preparation of phase-change temperature-regulating microcapsules:

[0012] n-octadecane, n-nonadecane, and n-heneicosane are mixed and melted to obtain a capsule core material; the capsule core material and diisocyanate are mixed uniformly to obtain an organic phase system; an emulsifier is added to water and mixed uniformly to obtain an aqueous phase system; the organic phase system is added to the aqueous phase system for emulsification and dispersion to obtain an emulsion; a chain extender is added to the emulsion for polymerization reaction to obtain a single-wall phase change temperature regulating microcapsule dispersion;

[0013] Adding gelatin and gum arabic to a dispersion of single-wall phase-change temperature-regulating microcapsules, mixing and stirring to form a suspension, and then adding a curing agent to carry out a cross-linking reaction to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules;

[0014] spray drying the double-wall phase-change temperature-regulating microcapsule dispersion to obtain phase-change temperature-regulating microcapsules;

[0015] (2) Preparation of cellulose spinning solution:

[0016] The cellulose pulp is added into the cellulose solvent and the cellulose spinning solution is prepared by using a thin film evaporator;

[0017] (3) Preparation of phase-change temperature-regulating microcapsule dispersion system:

[0018] The phase-change temperature-regulating microcapsules are added to an aqueous solution of a cellulose solvent having a concentration of 30 to 50 wt.%, and the dispersion is uniformly dispersed to obtain a phase-change temperature-regulating microcapsule dispersion system;

[0019] (4) Preparation of high enthalpy phase change temperature-adjustable lyocell fiber:

[0020] The cellulose spinning solution and the phase change temperature regulating microcapsule dispersion system are mixed and degassed by a single screw extruder to obtain a blended spinning solution, which is then spun and post-treated to obtain a high enthalpy phase change temperature regulating lyocell fiber.

[0021] In the present invention, the cellulose solvent is NMMO or an ionic liquid; the ionic liquid is preferably an alkyl imidazole type ionic liquid, wherein the cation is one of allyl, ethyl, and butyl, and the anion is one of halogen, SCN-, and CH3COO-.

[0022] In step (1), the mass ratio of n-octadecane, n-nonadecane and n-heneicosane is 50:(35-40):(10-15).

[0023] Preferably, n-octadecane, n-nonadecane and n-heneicosane are stirred at a temperature of 40 to 50° C. and a rotation speed of 350 to 600 r / min for 60 to 90 minutes to be mixed and melted.

[0024] Among phase change materials, n-octadecane has a crystallization temperature of 25.4°C, which best matches the human body's comfortable temperature range. Therefore, it is used as the primary phase change material. However, during the actual cooling crystallization process, n-octadecane can experience supercooling crystallization, meaning it crystallizes below its crystallization temperature. This causes the fiber to not crystallize at the temperature at which it should crystallize and release heat, thereby affecting the temperature-regulating effect. Therefore, the present invention incorporates n-nonadecane and n-henedecane into n-octadecane as phase change materials. The crystallization temperature of n-nonadecane is 26.4°C, slightly above the human body's comfortable temperature range, while the crystallization temperature of n-henedecane is 35.9°C, much higher than the human body's comfortable temperature range. The present invention introduces n-henedecane primarily as a "crystallization initiator." Based on research experience and results, the actual crystallization temperature of n-henedecane is near the crystallization temperature of n-nonadecane due to supercooling. This allows its crystallization energy to serve as a crystallization nucleus for n-nonadecane, promoting the crystallization of n-nonadecane, which in turn promotes the crystallization of n-octadecane near its crystallization temperature. This avoids the supercooling crystallization problem of n-nonadecane and n-octadecane, and improves the phase change temperature-regulating effect of the fiber.

[0025] In addition, compared with the introduction of high thermal conductivity materials such as carbon nanotubes and graphene oxide to improve the temperature regulation effect of the fiber, the n-nonadecane and n-heneicosane introduced in the present invention are similar substances and have good compatibility with n-octadecane, avoiding the compatibility problem with the capsule core material when adding foreign crystal cores, and will not affect the color of the fiber.

[0026] In step (1), the mass percentage of the core material in the organic phase system is 50-65%.

[0027] Preferably, the capsule core material and diisocyanate are stirred at a temperature of 40 to 45° C. and a rotation speed of 500 to 650 r / min for 60 to 90 minutes to obtain an organic phase system.

[0028] More preferably, the diisocyanate is toluene diisocyanate or isophorone diisocyanate.

[0029] In step (1), the mass percentage of the emulsifier in the aqueous phase system is 2.5-5%.

[0030] Preferably, the emulsifier is added to water and stirred at a temperature of 40 to 45° C. and a rotation speed of 500 to 650 r / min for 60 to 90 minutes to obtain an aqueous phase system.

[0031] Further preferably, the emulsifier is nonylphenol polyoxyethylene ether or styrene-maleic anhydride polymer sodium salt; and the water is deionized water.

[0032] In step (1), the mass percentage of the organic phase system in the emulsion is 35-50%.

[0033] Preferably, the emulsification and dispersion adopts a stator-rotor emulsification device with a rotor speed of 2500-3300 r / min, N2 atmosphere, temperature of 40-45°C, and the emulsification and dispersion is carried out until an emulsion with a particle size D97≤1.150 μm is formed.

[0034] In step (1), the mass of the chain extender added to the emulsion accounts for 3.5-7% of the mass of the diisocyanate in the organic phase system.

[0035] Preferably, the chain extender is at least one of 1,4-butanediol, ethylenediamine, and triethanolamine.

[0036] Preferably, the polymerization reaction temperature is 60-80°C and the reaction time is 3-4 hours. The resulting dispersion of single-wall phase-change temperature-regulating microcapsules has a particle size (D90) ranging from 1.321 to 1.439 μm. These single-wall phase-change temperature-regulating microcapsules utilize a core material as their core and polyurethane as their walls. The elasticity of the polyurethane wall reduces damage to the microcapsules during subsequent applications due to external influences such as pressure and friction, thereby improving their stability.

[0037] In step (1), when preparing the double-wall phase-change temperature-regulating microcapsule dispersion, the mass ratio of gelatin to gum arabic is 1:(1-1.2); the mass ratio of gelatin to the core material contained in the single-wall phase-change temperature-regulating microcapsule dispersion is (0.5-1):1; and the amount of curing agent added is 5-10% of the mass of gelatin.

[0038] Preferably, the curing agent is transglutaminase or carbodiimide.

[0039] Preferably, at a temperature of 45 to 50°C and a rotation speed of 500 to 650 r / min, gelatin is first added to a dispersion of single-wall phase-change temperature-regulating microcapsules, stirred to dissolve, and the pH value is adjusted to 4.0 to 6.0 with acetic acid or lactic acid, and then gum arabic is added for a complex coacervation reaction to obtain a suspension; then the suspension is cooled to 10 to 15°C, a curing agent is added, and sodium hydroxide is added to adjust the pH value to 7.5 to 8.5, and a cross-linking reaction is carried out for 90 to 130 minutes to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules, wherein the particle size D97 of the double-wall phase-change temperature-regulating microcapsules is ≤1.975 μm.

[0040] The double capsule wall design of the present invention can, on the one hand, effectively prevent the microcapsules from being damaged by mechanical friction and high temperature during the spinning process, thereby further improving the density and stability of the microcapsules; on the other hand, the outer capsule wall is made of gelatin and gum arabic, which contains hydrophilic groups such as amino, carboxyl, and hydroxyl groups. Compared with polyurethane, it has better compatibility with fibers and can be dissolved in cellulose solvents under certain conditions. In the early stage of the fiber preparation process, it plays a role in protecting the microcapsules, and in the later stage, it is dissolved in the cellulose solvent and finally formed as part of the fiber, so that the microcapsules form a cross-linked structure in the fiber, which plays a toughening role.

[0041] In step (1), the spray drying process conditions are: feed temperature 125-135°C, discharge temperature 75-90°C, air volume 2.5-5.0m 3 / h.

[0042] Preferably, in order to obtain cleaner phase change temperature regulating microcapsules, water washing and secondary spray drying can be performed after spray drying, which can reduce various impurities brought into the lyocell spinning system, reduce the impurity content of the spinning solvent, improve the solvent recovery rate, and reduce solvent waste.

[0043] In step (2), the cellulose pulp is obtained by activating pulp with an average degree of polymerization of 600-1000, a cellulose methyl content of 92-96 wt.%, and an ash content of ≤0.15 wt.% by cellulase, and has a moisture content of 50-60 wt.%.

[0044] Preferably, the activation process of cellulose pulp is as follows: the pulp is crushed and added into a cellulase activation solution with a pH value of 5-6 and a temperature of 45-50°C, activated for 30-60 minutes, adjusted to a pH value of 10-12, and squeezed to obtain cellulose pulp.

[0045] In step (2), the mass fraction of cellulose in the cellulose spinning solution is 9.5-13.0%. The temperature of the cellulose spinning solution is maintained at 92-98°C, and the solution is filtered and set aside.

[0046] In step (3), the mass fraction of the phase-change temperature-regulating microcapsules in the phase-change temperature-regulating microcapsule dispersion system is 35-45%.

[0047] Preferably, in order to disperse more evenly and quickly, a dual effect of strong stirring dispersion and ultrasonic assisted dispersion can be used to disperse until the droplet size reaches D97≤2.168μm, thereby obtaining a phase change temperature regulating microcapsule dispersion system.

[0048] Furthermore, the rotation speed of the strong stirring dispersion is preferably 3000-3500 r / min, and the power of the ultrasonic-assisted dispersion is preferably 350-450 W.

[0049] The present invention utilizes a relatively low-concentration cellulose solvent system to disperse the phase-change thermoregulating microcapsules, improving their compatibility with the cellulose spinning solution. Furthermore, the low-concentration cellulose solvent does not damage the walls of the double-walled phase-change thermoregulating microcapsules, thereby improving the stability of the microcapsules in the dispersed system. The concentration of the aqueous cellulose solvent solution must be controlled. If it is too high, it will dissolve the outer capsule wall, affecting the stability of the microcapsules. If it is too low, it will dilute the cellulose solvent concentration in the subsequent blended spinning solution, hindering the dissolution of the outer capsule wall during the spinning process.

[0050] In step (4), in the blended spinning solution, the mass of the phase change temperature regulating microcapsules contained in the phase change temperature regulating microcapsule dispersion system accounts for 20 to 80% of the mass of the cellulose contained in the cellulose spinning solution.

[0051] Preferably, the temperatures of the feeding section, dissolving section and head section of the single-screw extruder are 98-105°C, 100-110°C and 115-120°C respectively, the screw speed is 80-100 r / min, and the vacuum degree is -0.05--0.1 MPa.

[0052] In step (4), the spinning adopts a dry-wet spinning process, the blended spinning solution is measured by a metering pump, spun by a spinneret, and then spun into shape in a coagulation bath; wherein, the spinning speed is 35-50 m / min, the air gap layer adopts a side blowing method, the air gap layer length is 10-30 mm, the air gap temperature is 15-25° C., and the relative humidity is 60-80%; the coagulation bath is an aqueous solution of a cellulose solvent with a concentration of 18.0-23.0 wt.% and a temperature of 16-22° C.

[0053] During the mixing and spinning process of the blended spinning solution, the outer wall of the phase change temperature-regulating microcapsule will gradually dissolve in the cellulose solvent and form as part of the fiber, establishing cross-linking between the microcapsule and the fiber, thereby weakening the effect of the introduction of the microcapsule on the fiber strength.

[0054] In step (4), the post-treatment includes the following processes: drawing, washing, bleaching, one-stage drying, plasma etching, functional additive adsorption, oiling, cutting, two-stage drying, irradiation cross-linking, and fine opening.

[0055] Preferably, the stretching is performed using a five-roller or seven-roller stretching machine.

[0056] Preferably, the water washing adopts deionized water circulating spraying, the temperature is 60-75° C., and the pressure is 0.2-0.3 MPa.

[0057] Preferably, bleaching is performed by circulating spraying of a hydrogen peroxide aqueous solution with a concentration of 1.0 to 2.0 g / L, a pH value of 8.5 to 9.5, a temperature of 50 to 60° C., and a pressure of 0.2 to 0.3 MPa.

[0058] Preferably, the drying process adopts a drying cylinder mode, hot air drying, and the fiber tow is continuously wound on the drying cylinder at a drying temperature of 105-115°C.

[0059] Preferably, the plasma etching treatment conditions are: power 150-250 W, action time 50-100 s, reaction gas is air, and reaction pressure is 50-90 Pa. After plasma treatment, the surface structure of the blended fiber is etched, the surface area is increased, and it helps to increase the adsorption amount of subsequent functional additives.

[0060] Preferably, the functional adjuvant adsorption is carried out using a mixed aqueous solution of seaweed polysaccharide, chlorogenic acid and acrylic acid, wherein the seaweed polysaccharide concentration is 5-10wt.%, the chlorogenic acid concentration is 8-15wt.%, the acrylic acid concentration is 5-8wt.%, the pH value is 5.5-6.8, and the temperature is 70-80°C.

[0061] Preferably, the oiling is carried out by circulating spraying in an oil bath with a concentration of 4.0 to 7.0 g / L and a temperature of 60 to 75°C.

[0062] Preferably, the second drying step is vacuum drying at a temperature of 35-38° C. until the fiber regain reaches 10.8-12.5%. Low-temperature vacuum drying can avoid the destruction of functional additives such as chlorogenic acid in the fiber.

[0063] Preferably, the irradiation crosslinking treatment conditions are: accelerator energy of 1.0-1.5 MeV, room temperature, air atmosphere, and absorbed dose of 25-50 kGy. Irradiation crosslinking allows crosslinking between the functional additives adsorbed on the fibers and between the functional additives and the cellulose matrix, ensuring fiber functionality while minimizing fiber fibrillation. Furthermore, the sequence of these steps ensures that crosslinking occurs only within individual fibers, improving the fiber's feel.

[0064] The high-enthalpy phase-change temperature-regulating lyocell fiber prepared by the preparation method of the present invention has a dry breaking strength of ≥3.5 cN / dtex, a wet breaking strength of ≥2.3 cN / dtex (GB / T14337-2008), a phase-change melting temperature of 19.2-35.1°C, a melting enthalpy of 29.5-79.6 J / g, a phase-change crystallization temperature of 30.3-15.1°C, a crystallization enthalpy of 28.9-79.7 J / g (FZ / T 50061-2023), an Escherichia coli inhibition rate of ≥81%, a Candida albicans inhibition rate of ≥80% (GB / T20944.3-2008), and an ammonia reduction rate of ≥79% (GB / T33610.2-2017).

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] (1) The present invention uses a mixture of n-octadecane, n-nonadecane and n-henedecane as the capsule core material. During the cooling crystallization process, the n-henedecane that is first crystallized and solidified is used as the crystallization core of the n-nonadecane, and the n-henedecane that is crystallized and solidified is then used as the crystallization core of the n-octadecane. This avoids the supercooling crystallization of n-octadecane and n-nonadecane in the subsequently prepared microcapsules, reduces the supercooling degree of the microcapsules and the subsequent spinning fibers, and improves the phase change temperature regulation effect of the microcapsules. In addition, n-octadecane, n-nonadecane and n-henedecane are similar substances and have good compatibility, thus avoiding the compatibility problem with the capsule core material when adding an external crystallization core;

[0067] (2) The present invention adopts a phase-change temperature-regulating microcapsule with a double-wall structure, wherein the inner wall is made of polyurethane material, which has a certain elasticity and can reduce the damage of the microcapsule due to external influences such as pressure and friction during subsequent applications, thereby improving the stability of the microcapsule; the outer wall is made of gelatin and gum arabic, which has good compatibility with fibers and can be dissolved in cellulose solvents under certain conditions. In the early stage of the fiber preparation process, it plays a role in protecting the microcapsules, and in the later stage, it dissolves in the solvent and is finally formed as a part of the fiber, so that the microcapsules form a cross-linked structure in the fiber, which plays a toughening role;

[0068] (3) The present invention utilizes a low-concentration cellulose solvent system to disperse the phase-change thermostatic microcapsules, which not only improves their compatibility with the cellulose spinning solution, but also the low-concentration cellulose solvent does not damage the capsule wall of the double-wall phase-change thermostatic microcapsules, thereby improving the stability of the double-wall phase-change thermostatic microcapsules. The microcapsules can be dissolved later by increasing the concentration of the cellulose solvent.

[0069] (4) The present invention uses a thin film evaporator and a single-screw extruder in combination, which not only improves the melting effect of cellulose and the uniform mixing of cellulose and phase-change temperature-regulating microcapsules, but also realizes the simultaneous melting, supplementary dissolution, and vacuum degassing of cellulose, thereby improving production efficiency;

[0070] (5) The high enthalpy phase-change temperature-regulating lyocell fiber prepared by the present invention has good phase-change temperature-regulating, antibacterial and ammonia removal functions, and its dry breaking strength is ≥3.5cN / dtex, wet breaking strength is ≥2.3cN / dtex, phase-change melting temperature is 19.5-40.8°C, melting enthalpy is 29.5-79.6J / g, phase-change crystallization temperature is 26.3-17.9°C, crystallization enthalpy is 28.9-79.7J / g, Escherichia coli inhibition rate is ≥81%, Candida albicans inhibition rate is ≥80%, and ammonia reduction rate is ≥79%. It can be blended, pure spun or filled to make various clothing fabrics, thereby improving the comfort and functionality of the products. DETAILED DESCRIPTION

[0071] The present invention is further described below with reference to the examples. The raw materials used in the examples, unless otherwise specified, are all commercially available conventional raw materials; the process methods used in the examples, unless otherwise specified, are all conventional methods in the art. The examples of the present invention do not limit the levels of the amounts of the raw materials used, and any weight grade can be used for the preparation, as long as the specific raw material ratios are followed.

[0072] Example 1

[0073] A method for preparing high-enthalpy phase-change temperature-regulating lyocell fiber with a specification of 1.67 dtex×38 mm comprises the following steps:

[0074] (1) Preparation of phase-change temperature-regulating microcapsules:

[0075] A mixture of n-octadecane, n-nonadecane and n-heneicosane in a mass ratio of 50:40:10 was prepared, and the mixture was stirred at a temperature of 40° C. and a rotation speed of 350 r / min for 90 minutes to mix and melt to obtain a capsule core material;

[0076] The capsule core material and toluene diisocyanate with a mass ratio of 50:50 were stirred at a temperature of 40°C and a rotation speed of 500 r / min for 90 min to obtain an organic phase system;

[0077] 2.5 wt.% of nonylphenol polyoxyethylene ether was added to deionized water, and the mixture was stirred at 40° C. and 500 rpm for 90 minutes to obtain an aqueous phase system;

[0078] The organic phase system was added to the aqueous phase system in a mass ratio of 35:65, and the emulsification dispersion was performed using a stator-rotor emulsification device with a rotor speed of 2500 r / min, an N2 atmosphere, and a temperature of 40°C until an emulsion with a particle size of D97 = 1.023 μm was formed;

[0079] 1,4-Butanediol accounting for 3.5% of the mass of toluene diisocyanate in the organic phase system was added to the emulsion, and a polymerization reaction was carried out at 60°C for 4 hours to obtain a dispersion of single-wall phase-change temperature-regulating microcapsules with a core material as the core and polyurethane as the wall. The particle size of the single-wall phase-change temperature-regulating microcapsules is D90 = 1.321 μm;

[0080] At a temperature of 45°C and a rotation speed of 500 r / min, gelatin was added to a dispersion of single-wall phase-change temperature-regulating microcapsules at a mass ratio of 0.5:1 to the core material contained therein, stirred and dissolved, and the pH value was adjusted to 4.0 with acetic acid. Then, gum arabic was added at a mass ratio of 1:1 to the gelatin to perform a complex coacervation reaction to obtain a suspension. The suspension was then cooled to 10°C, carbodiimide accounting for 5% of the gelatin mass was added, and sodium hydroxide was added to adjust the pH value to 8.5. A cross-linking reaction was performed for 130 minutes to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules, wherein the particle size D97 of the double-wall phase-change temperature-regulating microcapsules was 1.815 μm.

[0081] The double-wall phase change temperature regulating microcapsule dispersion was spray dried, washed with water and spray dried twice to obtain high-clean phase change temperature regulating microcapsules. The feed temperature of the spray drying was 125℃, the discharge temperature was 75℃ and the air volume was 2.5m 3 / h;

[0082] (2) Preparation of cellulose spinning solution:

[0083] Pulp having an average degree of polymerization of 600, a cellulose alpha content of 92 wt.%, and an ash content of 0.15 wt.% is pulverized and then added to a cellulase activation solution having a pH of 5 and a temperature of 45°C for activation. After activation for 30 minutes, the pH is adjusted to 10 to terminate the activation, and the pulp is squeezed to obtain a cellulose pulp having a moisture content of 50 wt.%. The cellulose pulp is added to an NMMO solution and a cellulose spinning solution having a mass fraction of 9.5% is obtained using a thin film evaporator. The cellulose spinning solution is maintained at a temperature of 92°C, filtered, and set aside.

[0084] (3) Preparation of phase-change temperature-regulating microcapsule dispersion system:

[0085] Phase-change temperature-regulating microcapsules were added to a 30 wt.% NMMO aqueous solution and dispersed using both vigorous stirring and ultrasonic-assisted dispersion. The vigorous stirring speed was 3000 r / min, and the ultrasonic-assisted dispersion power was 450 W. The dispersion was performed until the droplet size reached D97 = 1.973 μm, thereby obtaining a phase-change temperature-regulating microcapsule dispersion.

[0086] (4) Preparation of high enthalpy phase change temperature-adjustable lyocell fiber:

[0087] The cellulose spinning solution and the phase-change temperature-regulating microcapsule dispersion system were mixed and degassed using a single-screw extruder to obtain a blended spinning solution, wherein the temperatures of the feeding section, dissolving section, and head section of the single-screw extruder were 98° C., 100° C., and 115° C., respectively, the screw speed was 80 r / min, and the vacuum degree was -0.1 MPa.

[0088] The blended spinning solution is spun, and then sequentially subjected to drawing, washing, bleaching, primary drying, plasma etching, functional additive adsorption, oiling, cutting, secondary drying, irradiation cross-linking, and fine opening to obtain high enthalpy phase change temperature-regulating lyocell fiber;

[0089] The spinning method adopts dry-jet wet spinning. The blended spinning solution is metered by a metering pump and spun by a spinneret. The yarn is then spun into shape in a coagulation bath at a spinning speed of 35 m / min. The air gap layer adopts a side blowing method with a length of 10 mm, an air gap temperature of 15°C, and a relative humidity of 80%. The coagulation bath is an 18.0 wt.% NMMO aqueous solution at a temperature of 16°C.

[0090] The drafting is carried out using a five-roller drafting machine;

[0091] The water washing adopts deionized water circulation spraying, the temperature is 60℃, and the pressure is 0.3MPa;

[0092] Bleaching was carried out by circulating spraying of a 1.0 g / L hydrogen peroxide aqueous solution with a pH value of 8.5, a temperature of 60°C, and a pressure of 0.2 MPa;

[0093] The first drying adopts the drying cylinder mode, hot air drying, and the fiber tow is continuously wound on the drying cylinder at a drying temperature of 105℃;

[0094] The plasma etching power is 150W, the action time is 50s, the reaction gas is air, and the reaction pressure is 90Pa;

[0095] Functional additive adsorption was performed using a mixed aqueous solution of seaweed polysaccharide, chlorogenic acid, and acrylic acid, wherein the seaweed polysaccharide concentration was 5 wt.%, the chlorogenic acid concentration was 8 wt.%, the acrylic acid concentration was 5 wt.%, the pH value was 5.5, and the temperature was 70°C;

[0096] The oiling was carried out by circulating spraying in an oil bath with a concentration of 4.0 g / L and a temperature of 60°C;

[0097] The second drying step uses vacuum drying at 35°C until the fiber moisture regain reaches 12.5%;

[0098] The accelerator energy of the irradiation cross-linking was 1.0 MeV, room temperature, air atmosphere, and the absorbed dose was 25 kGy.

[0099] Example 2

[0100] A method for preparing high-enthalpy phase-change temperature-regulating lyocell fiber with a specification of 2.22 dtex×38 mm comprises the following steps:

[0101] (1) Preparation of phase-change temperature-regulating microcapsules:

[0102] A mixture of n-octadecane, n-nonadecane, and n-heneicosane in a mass ratio of 50:37:13 was prepared, and the mixture was stirred at a temperature of 44° C. and a rotation speed of 500 r / min for 78 minutes to mix and melt to obtain a capsule core material;

[0103] The capsule core material and toluene diisocyanate in a mass ratio of 57:43 were stirred at a temperature of 43°C and a rotation speed of 576 r / min for 75 min to obtain an organic phase system;

[0104] 4 wt.% of nonylphenol polyoxyethylene ether was added to deionized water, and the mixture was stirred at 43°C and 565 rpm for 76 minutes to obtain an aqueous phase system;

[0105] The organic phase system was added to the aqueous phase system in a mass ratio of 44:56, and the emulsification dispersion was performed using a stator-rotor emulsification device with a rotor speed of 2800 r / min, an N2 atmosphere, and a temperature of 43°C until an emulsion with a particle size of D97 = 1.089 μm was formed;

[0106] Ethylene diamine (5% by weight of toluene diisocyanate in the organic phase) was added to the emulsion, and a polymerization reaction was carried out at 60°C for 3.5 hours to obtain a dispersion of single-wall phase-change temperature-regulating microcapsules with a core material as the core and polyurethane as the wall. The particle size of the single-wall phase-change temperature-regulating microcapsules was D90 = 1.396 μm.

[0107] At a temperature of 43°C and a rotation speed of 575 r / min, gelatin was added to a dispersion of single-wall phase-change temperature-regulating microcapsules at a mass ratio of 0.8:1 to the core material contained therein, stirred and dissolved, and the pH value was adjusted to 4.0 with acetic acid. Then, gum arabic was added at a mass ratio of 1.1:1 to the gelatin to perform a complex coacervation reaction to obtain a suspension. The suspension was then cooled to 12.5°C, transglutaminase accounting for 7.6% of the gelatin mass was added, and sodium hydroxide was added to adjust the pH value to 8.0. A cross-linking reaction was performed for 115 minutes to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules, wherein the particle size D97 of the double-wall phase-change temperature-regulating microcapsules was 1.901 μm.

[0108] The double-wall phase change temperature regulating microcapsule dispersion was spray dried, washed with water and spray dried twice to obtain high-clean phase change temperature regulating microcapsules. The feed temperature of the spray drying was 130℃, the discharge temperature was 82℃ and the air volume was 3.8m 3 / h;

[0109] (2) Preparation of cellulose spinning solution:

[0110] Pulp having an average degree of polymerization of 752, a cellulose alpha content of 93.8 wt.%, and an ash content of 0.12 wt.% was pulverized, then added to a cellulase activation solution having a pH of 5.5 and a temperature of 47°C for activation. After activation for 45 minutes, the pH was adjusted to 11 to terminate the activation, and the pulp was squeezed to obtain a cellulose pulp having a moisture content of 55.6 wt.%. The cellulose pulp was added to an alkyl imidazole-type ionic liquid (with an ethyl cation and an SCN-anion) and a cellulose spinning solution having a cellulose mass fraction of 11.3% was obtained using a thin film evaporator. The cellulose spinning solution was maintained at a temperature of 95.5°C, filtered, and set aside.

[0111] (3) Preparation of phase-change temperature-regulating microcapsule dispersion system:

[0112] Phase-change temperature-regulating microcapsules were added to a 41 wt.% aqueous solution of an alkyl imidazole-type ionic liquid (with ethyl as the cation and SCN- as the anion), and dispersed using both vigorous stirring and ultrasonic-assisted dispersion. The vigorous stirring speed was 3300 r / min, and the ultrasonic-assisted dispersion power was 400 W. The dispersion was performed until the droplet size reached D97 = 2.055 μm, thereby obtaining a phase-change temperature-regulating microcapsule dispersion.

[0113] (4) Preparation of high enthalpy phase change temperature-adjustable lyocell fiber:

[0114] The cellulose spinning solution and the phase-change temperature-regulating microcapsule dispersion system were mixed and degassed using a single-screw extruder to obtain a blended spinning solution, wherein the temperatures of the feeding section, dissolving section, and head section of the single-screw extruder were 102° C., 105° C., and 117° C., respectively; the screw speed was 90 r / min; and the vacuum degree was -0.07 MPa.

[0115] The blended spinning solution is spun, and then sequentially subjected to drawing, washing, bleaching, primary drying, plasma etching, functional additive adsorption, oiling, cutting, secondary drying, irradiation cross-linking, and fine opening to obtain high enthalpy phase change temperature-regulating lyocell fiber;

[0116] The spinning method adopts dry-wet spinning. The blended spinning solution is metered by a metering pump and spun by a spinneret. The yarn is then spun into shape in a coagulation bath at a spinning speed of 44 m / min. The air gap layer adopts a side-blowing method. The air gap layer length is 20 mm, the air gap temperature is 20° C., and the relative humidity is 70%. The coagulation bath is a 20.0 wt.% aqueous solution of an alkyl imidazole type ionic liquid (the cation is ethyl and the anion is SCN-) at a temperature of 20° C.

[0117] The drafting is carried out using a seven-roller drafting machine;

[0118] The water washing adopts deionized water circulation spraying, the temperature is 67℃, and the pressure is 0.25MPa;

[0119] Bleaching was carried out by circulating spraying of a 1.5 g / L hydrogen peroxide aqueous solution with a pH value of 9.0, a temperature of 55°C, and a pressure of 0.25 MPa;

[0120] The first drying adopts the drying cylinder mode, hot air drying, and the fiber tow is continuously wound on the drying cylinder at a drying temperature of 110℃;

[0121] The plasma etching power is 200 W, the action time is 50 s, the reaction gas is air, and the reaction pressure is 75 Pa;

[0122] Functional additive adsorption was performed using a mixed aqueous solution of seaweed polysaccharide, chlorogenic acid, and acrylic acid, wherein the seaweed polysaccharide concentration was 7.2 wt.%, the chlorogenic acid concentration was 11.6 wt.%, the acrylic acid concentration was 6.8 wt.%, the pH value was 6.2, and the temperature was 75°C;

[0123] The oiling was carried out by circulating spraying in an oil bath with a concentration of 5.5 g / L and a temperature of 68°C;

[0124] The second drying step uses vacuum drying at a temperature of 36.5°C until the fiber moisture regain reaches 11.3%;

[0125] The accelerator energy of the irradiation cross-linking was 1.3 MeV, room temperature, air atmosphere, and the absorbed dose was 38 kGy.

[0126] Example 3

[0127] A method for preparing high-enthalpy phase-change temperature-regulating lyocell fiber with a specification of 3.33 dtex×51 mm comprises the following steps:

[0128] (1) Preparation of phase-change temperature-regulating microcapsules:

[0129] A mixture of n-octadecane, n-nonadecane and n-heneicosane in a mass ratio of 50:35:15 was prepared, and the mixture was stirred at a temperature of 50° C. and a rotation speed of 600 r / min for 60 minutes to mix and melt to obtain a capsule core material;

[0130] The capsule core material and toluene diisocyanate in a mass ratio of 65:35 were stirred at a temperature of 45°C and a rotation speed of 650 r / min for 60 min to obtain an organic phase system;

[0131] 5 wt.% of styrene-maleic anhydride polymer sodium salt was added to deionized water, and the mixture was stirred at 45° C. and 650 rpm for 60 min to obtain an aqueous phase system;

[0132] The organic phase system was added to the aqueous phase system in a mass ratio of 50:50, and the emulsification dispersion was performed using a stator-rotor emulsification device with a rotor speed of 3300 r / min, an N2 atmosphere, and a temperature of 45°C until an emulsion with a particle size of D97 = 1.150 μm was formed;

[0133] Triethanolamine accounting for 7% of the mass of toluene diisocyanate in the organic phase system was added to the emulsion, and a polymerization reaction was carried out at 80°C for 3 hours to obtain a dispersion of single-wall phase-change temperature-regulating microcapsules with a core material as the core and polyurethane as the wall. The particle size of the single-wall phase-change temperature-regulating microcapsules was D90 = 1.439 μm;

[0134] At a temperature of 50° C. and a rotation speed of 650 r / min, gelatin was added to a dispersion of single-wall phase-change temperature-regulating microcapsules in a mass ratio of 1:1 to the core material contained therein, stirred and dissolved, and the pH value was adjusted to 6.0 with acetic acid. Then, gum arabic was added in a mass ratio of 1.2:1 to the gelatin to perform a complex coacervation reaction to obtain a suspension. The suspension was then cooled to 15° C., transglutaminase accounting for 10% of the gelatin mass was added, and sodium hydroxide was added to adjust the pH value to 7.5. A cross-linking reaction was performed for 90 minutes to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules, wherein the particle size D97 of the double-wall phase-change temperature-regulating microcapsules was 1.975 μm.

[0135] The double-wall phase change temperature regulating microcapsule dispersion was spray dried, washed with water and spray dried twice to obtain high-clean phase change temperature regulating microcapsules. The feed temperature of the spray drying was 135℃, the discharge temperature was 90℃ and the air volume was 5.0m 3 / h;

[0136] (2) Preparation of cellulose spinning solution:

[0137] Pulp having an average degree of polymerization of 1000, a cellulose alpha content of 96 wt.%, and an ash content of 0.10 wt.% was pulverized, then added to a cellulase activation solution having a pH of 6 and a temperature of 50° C. for activation. After activation for 60 minutes, the pH was adjusted to 12 to terminate the activation, and the pulp was squeezed to obtain a cellulose pulp having a moisture content of 50 wt.%. The cellulose pulp was added to an alkyl imidazole-type ionic liquid (with a butyl cation and a CH3COO- anion) and a cellulose spinning solution was obtained using a thin film evaporator, wherein the mass fraction of cellulose was 13%. The cellulose spinning solution was maintained at a temperature of 98° C. and filtered for later use.

[0138] (3) Preparation of phase-change temperature-regulating microcapsule dispersion system:

[0139] Phase-change temperature-regulating microcapsules were added to a 50 wt.% aqueous solution of an alkyl imidazole ionic liquid (with a butyl cation and a CH3COO- anion), and dispersed using a combination of vigorous stirring and ultrasonic-assisted dispersion. The vigorous stirring speed was 3500 r / min, and the ultrasonic-assisted dispersion power was 450 W. The dispersion was performed until the droplet size reached D97 = 2.168 μm, thereby obtaining a phase-change temperature-regulating microcapsule dispersion.

[0140] (4) Preparation of high enthalpy phase change temperature-adjustable lyocell fiber:

[0141] According to the requirement that the mass of the phase-change temperature-regulating microcapsules contained in the phase-change temperature-regulating microcapsule dispersion system accounts for 80% of the mass of cellulose in the cellulose spinning solution, the cellulose spinning solution and the phase-change temperature-regulating microcapsule dispersion system are mixed and degassed using a single-screw extruder to obtain a blended spinning solution, wherein the temperatures of the feeding section, dissolving section, and head section of the single-screw extruder are 105° C., 110° C., and 120° C., respectively, the screw speed is 100 r / min, and the vacuum degree is -0.05 MPa;

[0142] The blended spinning solution is spun, and then sequentially subjected to drawing, washing, bleaching, primary drying, plasma etching, functional additive adsorption, oiling, cutting, secondary drying, irradiation cross-linking, and fine opening to obtain high enthalpy phase change temperature-regulating lyocell fiber;

[0143] The spinning method adopts dry-wet spinning. The blended spinning solution is metered by a metering pump and spun by a spinneret. The yarn is then spun into shape in a coagulation bath at a spinning speed of 50 m / min. The air gap layer adopts a side-blowing method with a length of 30 mm. The air gap temperature is 25°C and the relative humidity is 60%. The coagulation bath is a 23.0 wt.% aqueous solution of an alkyl imidazole type ionic liquid (the cation is butyl and the anion is CH3COO-) at a temperature of 22°C.

[0144] The drafting is carried out using a five-roller drafting machine;

[0145] The water washing adopts deionized water circulation spraying, the temperature is 75℃, and the pressure is 0.2MPa;

[0146] Bleaching was carried out by circulating spraying of a 2.0 g / L hydrogen peroxide aqueous solution with a pH value of 9.5, a temperature of 50°C, and a pressure of 0.3 MPa;

[0147] The first drying adopts the drying cylinder mode, hot air drying, and the fiber tow is continuously wound on the drying cylinder at a drying temperature of 115℃;

[0148] The plasma etching power is 250W, the action time is 100s, the reaction gas is air, and the reaction pressure is 90Pa;

[0149] Functional additive adsorption was performed using a mixed aqueous solution of seaweed polysaccharide, chlorogenic acid, and acrylic acid, wherein the seaweed polysaccharide concentration was 10 wt.%, the chlorogenic acid concentration was 15 wt.%, the acrylic acid concentration was 8 wt.%, the pH value was 6.8, and the temperature was 80°C;

[0150] The oiling was carried out by circulating spraying in an oil bath with a concentration of 7.0 g / L and a temperature of 75°C;

[0151] The second drying step uses vacuum drying at 38°C until the fiber moisture regain reaches 10.8%;

[0152] The accelerator energy of the irradiation cross-linking was 1.5 MeV, room temperature, air atmosphere, and the absorbed dose was 50 kGy.

[0153] Comparative Example 1

[0154] The only difference between this embodiment and embodiment 1 is that, in step (1), n-heneicosane is not added when preparing the capsule core material. Instead, n-heneicosane is replaced with an equal mass of n-nonadecane. That is, a mixture of n-octadecane and n-nonadecane in a mass ratio of 50:50 is prepared and stirred at a temperature of 40° C. and a rotation speed of 350 r / min for 90 minutes to mix and melt to obtain the capsule core material. The remaining steps are the same as those in embodiment 1.

[0155] Comparative Example 2

[0156] The only difference between this embodiment and embodiment 1 is that in step (1), the phase change temperature regulating microcapsules prepared are single-wall phase change temperature regulating microcapsules, that is, the prepared single-wall phase change temperature regulating microcapsules dispersion with capsule core material as capsule core and polyurethane as capsule wall is directly spray dried, washed with water and spray dried twice to obtain high-clean phase change temperature regulating microcapsules, and the feed temperature of the spray drying is 125°C, the discharge temperature is 75°C, and the air volume is 2.5m 3 The remaining steps are the same as those in Example 1.

[0157] Comparative Example 3

[0158] The only difference between this embodiment and embodiment 1 is that in step (3), a high-concentration NMMO aqueous solution is used as the dispersing solvent when preparing the phase-change temperature-regulating microcapsule dispersion system. That is, the phase-change temperature-regulating microcapsules are added to an 80 wt.% NMMO aqueous solution and dispersed using a combination of vigorous stirring and ultrasonic-assisted dispersion. The vigorous stirring speed is 3000 r / min, and the ultrasonic-assisted dispersion power is 450 W. The dispersion is performed until the droplet size reaches D97 = 1.973 μm, thereby obtaining a phase-change temperature-regulating microcapsule dispersion. The remaining steps are the same as those in embodiment 1.

[0159] The phase-change temperature-regulating lyocell fibers prepared in each example and comparative example were subjected to performance tests. Dry and wet breaking strengths were tested according to the standard GB / T 14337-2008; phase-change melting temperature, melting enthalpy, phase-change crystallization temperature, and crystallization enthalpy were tested according to the standard FZ / T 50061-2023; Escherichia coli inhibition rate and Candida albicans inhibition rate were tested according to the standard GB / T 20944.3-2008; and ammonia reduction rate was tested according to the standard GB / T 33610.2-2017. The test results are shown in Table 1.

[0160] Table 1 Performance test results of phase change temperature regulating lyocell fibers prepared in various embodiments and comparative examples

[0161] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Dry breaking strength, cN / dtex 3.61 3.56 3.52 3.59 2.35 2.53 Wet breaking strength, cN / dtex 2.51 2.42 2.36 2.52 1.32 1.43 Phase transition melting temperature, ℃ 20.3～40.6 19.8～40.8 19.5～40.5 17.9～26.8 20.5～40.7 20.1～40.6 Melting enthalpy, J / g 29.5 53.2 79.6 29.3 28.1 28.4 Phase transition crystallization temperature, ℃ 25.9～17.1 26.0～17.9 26.3～18.5 19.6～6.1 25.7～16.8 25.6～16.9 Crystallization enthalpy, J / g 28.9 52.8 79.7 28.5 27.2 27.5 Escherichia coli inhibition rate, % 81.8 83.9 86.7 81.6 81.5 81.2 Candida albicans inhibition rate, % 80.6 83.1 86.0 80.7 80.4 80.8 Ammonia reduction rate, % 79.3 81.7 83.8 79.5 79.2 79.3

[0162] As can be seen from Table 1, the high enthalpy phase change temperature-regulating lyocell fiber prepared by the present invention has good phase change temperature-regulating, antibacterial and ammonia removal functions, its dry breaking strength is ≥3.5cN / dtex, wet breaking strength is ≥2.3cN / dtex, phase change melting temperature is 19.5~40.8℃, melting enthalpy is 29.5~79.6J / g, phase change crystallization temperature is 26.3~17.9℃, crystallization enthalpy is 28.9~79.7J / g, Escherichia coli inhibition rate is ≥81%, Candida albicans inhibition rate is ≥80%, and ammonia reduction rate is ≥79%. As the amount of phase change temperature-regulating microcapsules added increases, the melting enthalpy and crystallization enthalpy of the fiber increase accordingly, but the dry breaking strength and wet breaking strength of the fiber remain basically unchanged, indicating that the double-wall phase change temperature-regulating microcapsule structure of the present invention has little effect on the strength of the fiber.

[0163] Comparative Example 1, in which n-henedecane is omitted from the core material, significantly reduces the fiber's melting and crystallization temperatures, while maintaining similar performance. This is because the peak crystallization temperatures of n-octadecane, n-nonadecane, and n-henedecane are 25.4°C, 26.4°C, and 35.9°C, respectively. The absence of n-undecane and its crystallization core effect results in a lower phase transition melting temperature range, significantly decreasing the phase transition crystallization temperature from the theoretical value, indicating supercooling.

[0164] In Comparative Example 2, polyurethane single-wall phase change temperature-regulating microcapsules were used, and the melting enthalpy and crystallization enthalpy of the fiber decreased. This is because the microcapsules were damaged by friction, shearing, and other effects during the spinning process, causing a small amount of phase change material to be lost, thereby affecting the temperature-regulating effect of the fiber. In addition, the dry breaking strength and wet breaking strength of the fiber were also significantly reduced. This is because the compatibility of polyurethane with cellulose is lower than that of the gelatin-gum arabic product, and the spherical microcapsules cannot form a cross-linked structure with the fiber when formed during the spinning process, thereby affecting the strength of the fiber.

[0165] In Comparative Example 3, a high-concentration fiber solvent system is used as the solvent in the preparation of the phase change temperature-regulating microcapsule dispersion system. The melting enthalpy, crystallization enthalpy, dry breaking strength and wet breaking strength of the fiber are all reduced. This is because the high-concentration fiber solvent system will promote the dissolution of the outer capsule wall, thereby affecting the protective effect and cross-linking effect of the outer capsule wall.

Claims

1. A method for preparing high enthalpy phase-change temperature-regulating lyocell fiber, characterized in that: The following steps are involved: (1) Preparation of phase-change temperature-regulating microcapsules: n-octadecane, n-nonadecane, and n-heneicosane are mixed and melted to obtain a capsule core material; the capsule core material and diisocyanate are mixed uniformly to obtain an organic phase system; an emulsifier is added to water and mixed uniformly to obtain an aqueous phase system; the organic phase system is added to the aqueous phase system for emulsification and dispersion to obtain an emulsion; a chain extender is added to the emulsion for polymerization reaction to obtain a single-wall phase change temperature regulating microcapsule dispersion; Adding gelatin and gum arabic to a dispersion of single-wall phase-change temperature-regulating microcapsules, mixing and stirring to form a suspension, and then adding a curing agent to carry out a cross-linking reaction to obtain a dispersion of double-wall phase-change temperature-regulating microcapsules; spray drying the double-wall phase-change temperature-regulating microcapsule dispersion to obtain phase-change temperature-regulating microcapsules; (2) Preparation of cellulose spinning solution: The cellulose pulp is added into the cellulose solvent and the cellulose spinning solution is prepared by using a thin film evaporator; (3) Preparation of phase change temperature regulating microcapsule dispersion system: The phase-change temperature-regulating microcapsules are added to an aqueous solution of a cellulose solvent having a concentration of 30-50 wt.%, and dispersed uniformly to obtain a phase-change temperature-regulating microcapsule dispersion system; (4) Preparation of high enthalpy phase change temperature-adjustable lyocell fiber: The cellulose spinning solution and the phase change temperature regulating microcapsule dispersion system are mixed and degassed using a single-screw extruder to obtain a blended spinning solution, which is then spun and post-treated to obtain a high enthalpy phase change temperature regulating lyocell fiber. The cellulose solvent is NMMO or an alkyl imidazole type ionic liquid; In step (1), the mass ratio of n-octadecane, n-nonadecane and n-heneicosane is 50:(35-40):(10-15); The chain extender is at least one of 1,4-butanediol and triethanolamine; In step (2), the cellulose pulp is obtained by activating the pulp with an average degree of polymerization of 600-1000, a cellulose alpha content of 92-96 wt.%, and an ash content of ≤0.15 wt.% by cellulase, and the moisture content thereof is 50-60 wt.%. The mass fraction of cellulose in the cellulose spinning solution is 9.5-13.0%.

2. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: In step (1), in the organic phase system, the mass percentage of the capsule core material is 50-65%; in the aqueous phase system, the mass percentage of the emulsifier is 2.5-5%.

3. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: In step (1), the mass percentage of the organic phase system in the emulsion is 35-50%; the mass of the chain extender added to the emulsion accounts for 3.5-7% of the mass of the diisocyanate in the organic phase system.

4. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, wherein: In step (1), when preparing the double-wall phase-change temperature-regulating microcapsule dispersion, the mass ratio of gelatin to gum arabic is 1:(1-1.2); the mass ratio of gelatin to the capsule core material contained in the single-wall phase-change temperature-regulating microcapsule dispersion is (0.5-1):1; and the amount of curing agent added is 5-10% of the mass of gelatin.

5. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: In step (3), the mass fraction of the phase-change temperature-regulating microcapsules in the phase-change temperature-regulating microcapsule dispersion system is 35-45%.

6. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: In step (4), in the blended spinning solution, the mass of the phase change temperature regulating microcapsules contained in the phase change temperature regulating microcapsule dispersion system accounts for 20-80% of the mass of the cellulose contained in the cellulose spinning solution.

7. A high enthalpy phase-change temperature-regulating lyocell fiber prepared by the preparation method according to any one of claims 1 to 6, characterized in that: Dry breaking strength ≥3.5cN / dtex, wet breaking strength ≥2.3cN / dtex, phase change melting temperature 19.5~40.8℃, melting enthalpy 29.5~79.6J / g, phase change crystallization temperature 26.3~17.9℃, crystallization enthalpy 28.9~79.7J / g, Escherichia coli inhibition rate ≥81%, Candida albicans inhibition rate ≥80%, ammonia reduction rate ≥79%.