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

Abstract

The invention belongs to the technical field of lyocell fibers, and particularly relates to a high-enthalpy-value phase-change temperature-adjusting lyocell fiber and a preparation method thereof. The preparation method of the high-enthalpy-value phase-change temperature-adjusting lyocell fiber comprises the following steps: preparing phase-change temperature-adjusting microcapsules by taking a mixture of n-octadecane, n-nonadecane and n-heneicosane as a capsule core material, taking polyurethane as an inner capsule wall and taking a product of gelatin and Arabic gum as an outer capsule wall; adding cellulose pulp into a cellulose solvent to prepare a cellulose spinning solution; adding the phase-change temperature-regulating microcapsules into an aqueous solution of a low-concentration cellulose solvent to prepare a phase-change temperature-regulating microcapsule dispersion system; and carrying out mixed spinning on the cellulose spinning solution and the phase-change temperature-regulating microcapsule dispersion system to prepare the high-enthalpy-value phase-change temperature-regulating lyocell fiber. According to the prepared high-enthalpy-value phase-change temperature-adjusting lyocell fiber, the phase-change temperature-adjusting microcapsules contained in the fiber are good in dispersity and compatibility in the fiber, and the high-enthalpy-value phase-change temperature-adjusting lyocell fiber has a good phase-change temperature-adjusting function and toughness.

Description

Technical Field

[0001] The present 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 fibers are fibers made from natural cellulose as raw materials, without changing their chemical structure, but only changing their physical structure. Regenerated cellulose fibers can not only maintain the advantages of natural fibers, but also endow products with more functions through innovation in production technology, becoming the best substitute for natural fibers. Among them, Lyocell fibers are regenerated cellulose fibers prepared by a dry-jet wet-spinning process using N-methylmorpholine-N-oxide (NMMO) as a direct solvent for cellulose. Compared with viscose fibers, the production process of Lyocell fibers is simple, green, and their performance is excellent, with strong market competitiveness and good development prospects.

[0003] Phase-change temperature-regulating fibers are a kind of heat storage and temperature-regulating functional fibers developed by utilizing the characteristics of releasing or absorbing latent heat and maintaining a constant temperature during the phase change process of substances. They have a two-way automatic temperature-regulating function and can play a temperature buffering role when used in clothing, reducing the change in skin temperature and prolonging the comfort of the wearer. Therefore, preparing phase-change temperature-regulating cellulose fibers based on Lyocell fibers has become a research hotspot of functional regenerated cellulose fibers. Currently, the most commonly used methods for preparing phase-change temperature-regulating Lyocell fibers are the blending method and the microcapsule method.

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

[0005] For example, in the temperature-regulating fiber preparation method disclosed in Patent CN110886026A, a semi-refined paraffin mixture is directly added to the spinning slurry of Lyocell fibers as the phase-change material. During the preparation process, the temperature of some baths is much higher than the melting temperature of the phase-change material, which will cause more loss of the phase-change material, affect the functionality of the fiber, and also affect the recovery of NMMO. In the preparation method of Lyocell fibers with phase-change temperature-regulating function disclosed in Patent CN117166076A, dodecane with a relatively high melting temperature (37.8°C) is used as the phase-change material and added to the NMMO solution to prepare the spinning dope, so as to reduce its loss during the preparation process. However, the phase-change crystallization temperature of dodecane is relatively high, and its temperature buffering effect is limited.

[0006] The microcapsule 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 fibers prepared by this method have the advantages of uniform dispersion of the phase-change material and no leakage.

[0007] For example, the high enthalpy phase-change temperature-adjusting lyocell fiber disclosed in patent CN113604896A is made of lyocell fiber and phase-change temperature-adjusting microcapsules cross-linked with lyocell fiber, wherein the phase-change temperature-adjusting microcapsules include capsule walls and capsule cores, the capsule cores include phase-change materials and nano-nucleating agents, and the capsule walls include melamine-modified urea-formaldehyde resin prepolymers. This invention uses microcapsules to reduce the loss of phase-change materials, but formaldehyde and glutaraldehyde are used in the preparation of microcapsules, which easily cause excessive formaldehyde in the fiber, 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 materials, carbon nanotubes, emulsifiers and resins. It mainly improves the thermal conductivity of the phase-change material by adding carbon nanotubes, but the introduction of carbon nanotubes will give the fiber a black attribute, resulting in limited application of the fiber. Similarly, the preparation method of heat storage and temperature regulating Lyocell fiber disclosed in patent CN119308031A is to improve the heat absorption and temperature regulating performance of the fiber by introducing graphene oxide and phase change microcapsules. The introduction of graphene oxide will also give the fiber a black attribute, resulting in limited application of the fiber. In addition, the above patents all use single-layer polyurethane capsule wall microcapsules. On the one hand, the single-layer capsule wall has limited protection effect on the capsule core during the fiber spinning process, and some microcapsules will still be damaged. On the other hand, the microcapsule is a spherical structure, which will affect the toughness of the fiber and cause a decrease in fiber 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 view of 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 color of the fiber itself, and have good phase change temperature-regulating, antibacterial and ammonia removal functions; the present invention also provides a preparation method thereof, which is feasible in process 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] The 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 evenly to obtain an organic phase system; an emulsifier is added to water and mixed evenly 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 capsule wall phase change temperature regulating microcapsule dispersion;

[0013] Gelatin and gum arabic are added to the single capsule wall phase change temperature regulating microcapsule dispersion, and mixed and stirred to form a suspension, and then a curing agent is added for cross-linking reaction to obtain a double capsule wall phase change temperature regulating microcapsule dispersion;

[0014] The double capsule wall phase change temperature regulating microcapsule dispersion is spray-dried to obtain phase change temperature regulating microcapsules;

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

[0016] Cellulose pulp is added to a cellulose solvent, and a cellulose spinning dope 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 with a concentration of 30-50 wt.%, and dispersed evenly to obtain a phase change temperature regulating microcapsule dispersion system;

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

[0020] The cellulose spinning dope and the phase change temperature regulating microcapsule dispersion system are mixed and degassed by using a single screw extruder to obtain a blended spinning dope, and then spun and post-treated to obtain 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 alkylimidazole 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 for 60-90 min at a temperature of 40-50 °C and a rotation speed of 350-600 r / min for mixing and melting.

[0024] In phase change materials, the crystallization temperature of n-octadecane is 25.4 °C, which is most in line with the comfortable temperature range of the human body. Therefore, it is used as the main phase change material. However, in the actual cooling and crystallization process, n-octadecane has a supercooled crystallization situation, that is, it crystallizes at a temperature lower than the crystallization temperature. This will cause the fiber not to crystallize at the temperature when it should crystallize and release heat, thus affecting the temperature regulation effect. Therefore, in the present invention, n-nonadecane and n-heneicosane are incorporated into n-octadecane as phase change materials. Among them, the crystallization temperature of n-nonadecane is 26.4 °C, slightly higher than the comfortable temperature range of the human body, while the crystallization temperature of n-heneicosane is 35.9 °C, much higher than the comfortable temperature range of the human body. The introduction of n-heneicosane in the present invention is mainly used as a "crystallization inducer". According to research experience and results, due to supercooling, the actual crystallization temperature of n-heneicosane will be near the crystallization temperature of n-nonadecane. This enables its crystallization to serve as the crystallization nucleus of n-nonadecane to promote the crystallization of n-nonadecane, and further promotes the crystallization of n-octadecane near its crystallization temperature, thereby avoiding the supercooled crystallization problems of n-nonadecane and n-octadecane and improving the phase change temperature regulation effect of the fiber.

[0025] In addition, compared with introducing highly thermally conductive substances such as carbon nanotubes and graphene oxide to improve the temperature regulation effect of fibers, the n-nonadecane and n-heneicosane introduced in the present invention are of the same kind as n-octadecane and have good compatibility, avoiding the compatibility problems with the core material when adding foreign crystallization nuclei and also not affecting the color of the fiber.

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

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

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

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

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

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

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

[0033] Preferably, a stator-rotor emulsifying device is used for emulsification and dispersion. The rotational speed of the rotor is 2500 - 3300 r / min, under a nitrogen atmosphere, at a temperature of 40 - 45°C, and emulsification and dispersion are 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 time is 3 - 4 h. In the single-wall phase-change temperature-regulating microcapsule dispersion obtained after the reaction, the particle size D90 of the single-wall phase-change temperature-regulating microcapsules is between 1.321 - 1.439 μm. The single-wall phase-change temperature-regulating microcapsules have a core material as the core and polyurethane as the wall. Since the polyurethane material of the wall has a certain elasticity, it can reduce the damage of the microcapsules caused by external influences such as pressure and friction during subsequent applications, thereby improving the stability of the microcapsules.

[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; the addition amount of the curing agent is 5 - 10% of the mass of gelatin.

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

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

[0040] Through the design of the double capsule wall, on the one hand, the microcapsules can be effectively prevented from being damaged due to mechanical friction and high temperature during the spinning process, further improving the compactness and stability of the microcapsules; on the other hand, the outer capsule wall is prepared from gelatin and gum arabic. This product contains hydrophilic groups such as amino, carboxyl, and hydroxyl groups, and has better compatibility with fibers compared to polyurethane. And under certain conditions, it can be dissolved in the cellulose solvent, playing a role in protecting the microcapsules in the early stage of fiber preparation, and then dissolving in the cellulose solvent and finally forming as part of the fiber, enabling the microcapsules to form a cross-linked structure in the fiber and playing a toughening role.

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

[0042] Preferably, in order to obtain cleaner phase change temperature-regulating microcapsules, water washing and secondary spray drying can be carried out after spray drying. This 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 the waste of the solvent.

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

[0044] Preferably, the activation process of the cellulose pulp is as follows: after crushing the pulp, add it to a cellulase activation solution with a pH value of 5 - 6 and a temperature of 45 - 50 °C. After activating for 30 - 60 min, adjust the pH value to 10 - 12 and perform pressing to obtain the cellulose pulp.

[0045] In step (2), in the cellulose spinning dope, the mass fraction of cellulose is 9.5 - 13.0%. Keep the temperature of the cellulose spinning dope at 92 - 98 °C, filter it, and reserve it for use.

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

[0047] Preferably, in order to achieve faster and more uniform dispersion, the double action of strong stirring dispersion and ultrasonic-assisted dispersion can be adopted. Disperse until the droplet size reaches D97 ≤ 2.168 μm to obtain the 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 temperature-regulating microcapsules, which can improve their compatibility with the cellulose spinning dope. At the same time, the low-concentration cellulose solvent will not damage the capsule wall of the double-capsule-wall phase-change temperature-regulating microcapsules, thereby enhancing the stability of the double-capsule-wall phase-change temperature-regulating microcapsules in the dispersion system. Here, it is necessary to control the concentration of the cellulose solvent aqueous solution. 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 concentration of the cellulose solvent in the subsequent blended spinning dope, which is not conducive to the dissolution of the outer capsule wall of the microcapsules during the spinning process.

[0050] In step (4), in the blended spinning dope, 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 dope.

[0051] Preferably, the temperatures of the feeding section, dissolution 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 to -0.1 MPa.

[0052] In step (4), dry-jet wet spinning is used for spinning. After the blended spinning dope is metered by a metering pump and spun through a spinneret, it is spun and formed in a coagulation bath. Among them, the spinning speed is 35-50 m / min, the air-gap layer uses side blowing, the length of the air-gap layer 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 the temperature is 16-22°C.

[0053] During the mixing and spinning process of the blended spinning dope, the outer capsule wall of the phase-change temperature-regulating microcapsules will gradually dissolve in the cellulose solvent and form as part of the fiber, establishing a crosslink between the microcapsules and the fiber, thereby weakening the influence of the introduction of the microcapsules on the fiber strength.

[0054] In step (4), the post-treatment includes the following processes: drawing, water washing, bleaching, first drying, plasma etching, functional additive adsorption, oiling, cutting, second drying, irradiation crosslinking, and fine opening of cotton.

[0055] Preferably, the drawing is carried out using a five-roll or seven-roll drawing machine.

[0056] Preferably, the water washing is carried out by circulating and spraying deionized water at a temperature of 60-75°C and a pressure of 0.2-0.3 MPa.

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

[0058] Preferably, the first drying is carried out in a drying cylinder mode with hot air drying. The fiber tow is continuously wound around the drying cylinder, and the drying temperature is 105 - 115°C.

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

[0060] Preferably, the adsorption of functional additives is carried out using an aqueous solution mixture of algal polysaccharide, chlorogenic acid, and acrylic acid. Among them, the concentration of algal polysaccharide is 5 - 10 wt.%, the concentration of chlorogenic acid is 8 - 15 wt.%, the concentration of acrylic acid is 5 - 8 wt.%, the pH value is 5.5 - 6.8, and the temperature is 70 - 80°C.

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

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

[0063] Preferably, the processing conditions for irradiation crosslinking are as follows: accelerator energy 1.0 - 1.5 MeV, room temperature, air atmosphere, and absorption dose 25 - 50 kGy. Irradiation crosslinking causes crosslinking between the adsorbed functional additives and between the functional additives and the cellulose matrix, which not only ensures the functionality of the fiber but also reduces the fibrillation problem of the fiber. At the same time, the setting of the above process sequence enables crosslinking to occur only within a single fiber, improving the handle of the fiber.

[0064] The high-enthalpy phase-change temperature-regulating Lyocell fiber prepared by the preparation method described in the present invention has a dry breaking strength ≥ 3.5 cN / dtex, a wet breaking strength ≥ 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 ≥ 81%, a Candida albicans inhibition rate ≥ 80% (GB / T20944.3 - 2008), and an ammonia reduction rate ≥ 79% (GB / T33610.2 - 2017).

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] (1) The present invention uses a mixture of n-octadecane, n-nonadecane, and n-heneicosane as the core material of the microcapsules. During the cooling crystallization process, the first solidified n-heneicosane is used as the crystallization nucleus of n-nonadecane, and then the solidified n-nonadecane is used as the crystallization nucleus of n-octadecane, avoiding the supercooled crystallization of n-octadecane and n-nonadecane in the subsequently prepared microcapsules, reducing the supercooling degree of the microcapsules and the subsequently spun fibers, improving the phase change temperature regulation effect of the microcapsules. Moreover, n-octadecane, n-nonadecane, and n-heneicosane are of the same kind of substances and have good compatibility, avoiding the compatibility problem with the core material when adding foreign crystallization nuclei;

[0067] (2) The present invention uses a phase change temperature regulation microcapsule with a double capsule wall structure. The inner capsule wall is made of polyurethane material and has a certain elasticity, which can reduce the damage of the microcapsules caused by external influences such as pressure and friction during subsequent applications, thereby improving the stability of the microcapsules; the outer capsule wall is prepared from gelatin and gum arabic. This product has good compatibility with fibers and can be dissolved in cellulose solvents under certain conditions. It plays a role in protecting the microcapsules in the early stage of fiber preparation, and later dissolves in the solvent and finally forms as part of the fiber, enabling the microcapsules to form a cross-linked structure in the fiber and playing a toughening role;

[0068] (3) The present invention disperses the phase change temperature regulation microcapsules using a low-concentration cellulose solvent system, which not only improves its compatibility with the cellulose spinning dope, but also the low-concentration cellulose solvent will not damage the capsule wall of the double capsule wall phase change temperature regulation microcapsules, improving the stability of the double capsule wall phase change temperature regulation microcapsules, and then dissolving them by increasing the concentration of the cellulose solvent in the later stage;

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

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

[0071] The present invention will be further described below in conjunction with embodiments. The raw materials used in the embodiments are all commercially available conventional raw materials unless otherwise specified; the process methods used in the embodiments are all conventional methods in the art unless otherwise specified. The embodiments of the present invention have no limitation on the dosage levels of the various raw materials, and any weight class can be used for preparation as long as the specific raw material ratio is followed.

[0072] Example 1

[0073] A preparation method of high-enthalpy phase-change temperature-regulating Lyocell fiber with a specification of 1.67 dtex × 38 mm includes the following steps:

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

[0075] Mix n-octadecane, n-nonadecane, and n-heneicosane with a mass ratio of 50:40:10 to form a mixture, stir at a temperature of 40 °C and a rotation speed of 350 r / min for 90 min for mixing and melting to obtain the core material;

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

[0077] Add 2.5 wt.% nonylphenol polyoxyethylene ether to deionized water, stir at a temperature of 40 °C and a rotation speed of 500 r / min for 90 min to obtain an aqueous phase system;

[0078] According to the mass ratio of the organic phase system to the aqueous phase system of 35:65, add the organic phase system to the aqueous phase system for emulsification and dispersion. The emulsification and dispersion use a stator-rotor type emulsifying device, with a rotor speed of 2500 r / min, an N2 atmosphere, and a temperature of 40 °C, and emulsify and disperse until an emulsion with a particle size D97 = 1.023 μm is formed;

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

[0080] Under the conditions of a temperature of 45 °C and a rotation speed of 500 r / min, gelatin with a mass ratio of 0.5:1 to the core material contained therein was added to the single-wall phase-change temperature-regulating microcapsule dispersion liquid, stirred and dissolved, and the pH value was adjusted to 4.0 with acetic acid. Then, gum arabic with a mass ratio of 1:1 to the gelatin was added for complex coacervation reaction to obtain a suspension; then the suspension was cooled to 10 °C, 5% of carbodiimide based on the mass of the gelatin was added, and the pH value was adjusted to 8.5 with sodium hydroxide for cross-linking reaction for 130 min to obtain a double-wall phase-change temperature-regulating microcapsule dispersion liquid, where 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 liquid was subjected to spray drying, water washing and secondary spray drying to obtain highly clean phase-change temperature-regulating microcapsules. The feed temperature of the spray drying was 125 °C, the discharge temperature was 75 °C, and the air volume was 2.5 m 3 / h;

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

[0083] The pulp with an average degree of polymerization of 600, a content of alpha-cellulose of 92 wt.%, and an ash content of 0.15 wt.% was pulverized, and then added to a cellulose enzyme activation solution with a pH value of 5 and a temperature of 45 °C for activation. After 30 min of activation, the pH value was adjusted to 10 to end the activation, and pressing was carried out to obtain a cellulose pulp with a water content of 50 wt.%; the cellulose pulp was added to an NMMO solution, and a cellulose spinning dope was obtained using a thin-film evaporator, where the mass fraction of cellulose was 9.5%. The temperature of the cellulose spinning dope was maintained at 92 °C, and it was filtered and reserved for use;

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

[0085] The phase-change temperature-regulating microcapsules were added to an NMMO aqueous solution with a concentration of 30 wt.%, and dispersed by the dual action of strong stirring dispersion and ultrasonic-assisted dispersion. The rotation speed of the strong stirring dispersion was 3000 r / min, and the power of the ultrasonic-assisted dispersion was 450 W. The dispersion was carried out until the droplet particle size reached D97 = 1.973 μm to obtain a phase-change temperature-regulating microcapsule dispersion;

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

[0087] According to the fact that the mass of the phase-change temperature-regulating microcapsules contained in the phase-change temperature-regulating microcapsule dispersion system accounted for 20% of the mass of cellulose in the cellulose spinning dope, the cellulose spinning dope and the phase-change temperature-regulating microcapsule dispersion system were mixed and degassed using a single-screw extruder to obtain a blended spinning dope. The temperatures of the feeding section, dissolution section and head section of the single-screw extruder were 98 °C, 100 °C and 115 °C respectively, the screw rotation 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 adopts dry-jet wet spinning, the blended spinning solution is metered by a metering pump, spun by a spinneret, and then spun in a coagulation bath, the spinning speed is 35 m / min, the air gap layer adopts a side blowing method, the air gap layer length is 10 mm, the air gap temperature is 15° C., and the relative humidity is 80%; the coagulation bath is a 18.0wt.% NMMO aqueous solution, the temperature is 16° C.;

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

[0091] The water washing adopts deionized water circulation spraying, the temperature is 60℃, 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, and the drying temperature is 105℃;

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

[0095] The functional additive adsorption is carried out by using a mixed aqueous solution of seaweed polysaccharide, chlorogenic acid and acrylic acid, wherein the seaweed polysaccharide concentration is 5wt.%, the chlorogenic acid concentration is 8wt.%, the acrylic acid concentration is 5wt.%, the pH value is 5.5, and the temperature is 70°C;

[0096] The oiling is carried out by circulating spraying in an oil bath with a concentration of 4.0g / 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 for 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-adjustable lyocell fiber with a specification of 2.22 dtex×38 mm, comprising the following steps:

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

[0102] Prepare a mixture of n-octadecane, n-nonadecane, and n-heneicosane with a mass ratio of 50:37:13. Stir at a temperature of 44 °C and a rotation speed of 500 r / min for 78 min for mixing and melting to obtain the core material.

[0103] Stir the core material and toluene diisocyanate with a mass ratio of 57:43 at a temperature of 43 °C and a rotation speed of 576 r / min for 75 min to obtain an organic phase system.

[0104] Add 4 wt.% nonylphenol polyoxyethylene ether to deionized water. Stir at a temperature of 43 °C and a rotation speed of 565 r / min for 76 min to obtain an aqueous phase system.

[0105] According to the mass ratio of the organic phase system to the aqueous phase system being 44:56, add the organic phase system to the aqueous phase system for emulsification and dispersion. Use a stator-rotor type emulsification device for emulsification and dispersion, with a rotor speed of 2800 r / min, an N2 atmosphere, and a temperature of 43 °C. Emulsify and disperse until an emulsion with a particle size D97 = 1.089 μm is formed.

[0106] Add ethylenediamine accounting for 5% of the mass of toluene diisocyanate in the organic phase system to the emulsion. Carry out a polymerization reaction at 60 °C for 3.5 h to obtain a single-wall phase change temperature-regulating microcapsule dispersion with the core material as the core and polyurethane as the wall. The particle size D90 of the single-wall phase change temperature-regulating microcapsule is 1.396 μm.

[0107] At a temperature of 43 °C and a rotation speed of 575 r / min, add gelatin with a mass ratio of 0.8:1 to the core material contained in the single-wall phase change temperature-regulating microcapsule dispersion. Stir and dissolve, and adjust the pH value to 4.0 with acetic acid. Then add gum arabic with a mass ratio of 1.1:1 to the gelatin for complex coacervation reaction to obtain a suspension; then cool the suspension to 12.5 °C, add transglutaminase accounting for 7.6% of the mass of the gelatin, and adjust the pH value to 8.0 with sodium hydroxide for a cross-linking reaction for 115 min to obtain a double-wall phase change temperature-regulating microcapsule dispersion, where the particle size D97 of the double-wall phase change temperature-regulating microcapsule is 1.901 μm.

[0108] Carry out spray drying, water washing, and secondary spray drying on the double-wall phase change temperature-regulating microcapsule dispersion to obtain highly clean phase change temperature-regulating microcapsules. The feed temperature for spray drying is 130 °C, the discharge temperature is 82 °C, and the air volume is 3.8 m 3 / h;

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

[0110] The pulp with an average degree of polymerization of 752, a content of alpha-cellulose of 93.8 wt.%, and an ash content of 0.12 wt.% is pulverized and then added to a cellulase activation solution with a pH value of 5.5 and a temperature of 47 °C for activation. After 45 minutes of activation, the pH value is adjusted to 11 to end the activation, and then pressing is carried out to obtain a cellulose pulp with a water content of 55.6 wt.%. The cellulose pulp is added to an alkylimidazolium-based ionic liquid (cation: ethyl, anion: SCN-), and a cellulose spinning dope is obtained using a thin-film evaporator, where the mass fraction of cellulose is 11.3%. The temperature of the cellulose spinning dope is maintained at 95.5 °C, and it is filtered and reserved for use.

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

[0112] The phase-change temperature-regulating microcapsules are added to an aqueous solution of an alkylimidazolium-based ionic liquid (cation: ethyl, anion: SCN-) with a concentration of 41 wt.%, and dispersion is carried out by the dual action of strong stirring dispersion and ultrasonic-assisted dispersion. The rotation speed of the strong stirring dispersion is 3300 r / min, and the power of the ultrasonic-assisted dispersion is 400 W. Dispersion is carried out until the droplet diameter reaches D97 = 2.055 μm, and thus the phase-change temperature-regulating microcapsule dispersion is obtained.

[0113] (4) Preparation of the high-enthalpy phase-change temperature-regulating Lyocell fiber:

[0114] According to the fact that the mass of the phase-change temperature-regulating microcapsules contained in the phase-change temperature-regulating microcapsule dispersion system accounts for 50% of the mass of cellulose in the cellulose spinning dope, the cellulose spinning dope and the phase-change temperature-regulating microcapsule dispersion system are mixed and degassed using a single-screw extruder to obtain a blended spinning dope. The temperatures of the feeding section, melting section, and head section of the single-screw extruder are 102 °C, 105 °C, and 117 °C respectively, the screw rotation speed is 90 r / min, and the vacuum degree is -0.07 MPa.

[0115] The above-mentioned blended spinning dope is spun, and then successively subjected to drawing, washing, bleaching, first drying, plasma etching, functional additive adsorption, oiling, cutting, second drying, irradiation crosslinking, and fine opening of cotton to obtain the high-enthalpy phase-change temperature-regulating Lyocell fiber.

[0116] Among them, dry-jet wet spinning is used for spinning. After the blended spinning dope is metered by a metering pump and spun through a spinneret, it is spun and formed in a coagulation bath. The spinning speed is 44 m / min, the air-gap layer uses a side-blowing method, the length of the air-gap layer is 20 mm, the air-gap temperature is 20 °C, and the relative humidity is 70%; the coagulation bath is an aqueous solution of an alkylimidazolium-based ionic liquid (cation: ethyl, anion: SCN-) with a concentration of 20.0 wt.%, and the temperature is 20 °C.

[0117] Drawing is carried out using a seven-roll drawing machine.

[0118] Water washing is carried out by circulating and spraying deionized water, with a temperature of 67 °C and a pressure of 0.25 MPa;

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

[0120] The first drying is carried out in a drying cylinder mode with hot air drying. The fiber tow is continuously wound around the drying cylinder, and the drying temperature is 110 °C;

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

[0122] The adsorption of functional additives is carried out by using a mixed aqueous solution of algal polysaccharide, chlorogenic acid, and acrylic acid for adsorption. Among them, the concentration of algal polysaccharide is 7.2 wt.%, the concentration of chlorogenic acid is 11.6 wt.%, the concentration of acrylic acid is 6.8 wt.%, the pH value is 6.2, and the temperature is 75 °C;

[0123] Oil application is carried out by circulating and spraying an oil bath with a concentration of 5.5 g / L, and the temperature is 68 °C;

[0124] The second drying is carried out by vacuum drying at a temperature of 36.5 °C until the fiber moisture regain is 11.3%;

[0125] The accelerator energy for irradiation crosslinking is 1.3 MeV, at room temperature, in an air atmosphere, and the absorbed dose is 38 kGy.

[0126] Example 3

[0127] A preparation method of high-enthalpy phase-change temperature-regulating Lyocell fiber with a specification of 3.33 dtex × 51 mm, comprising the following steps:

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

[0129] A mixture is prepared by mixing n-octadecane, n-nonadecane, and n-heneicosane with a mass ratio of 50:35:15, and stirred for 60 min at a temperature of 50 °C and a rotation speed of 600 r / min for mixing and melting to obtain a core material;

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

[0131] 5 wt.% of sodium styrene-maleic anhydride polymer is added to deionized water, and stirred for 60 min at a temperature of 45 °C and a rotation speed of 650 r / min to obtain an aqueous phase system;

[0132] According to the mass ratio of the organic phase system to the aqueous phase system being 50:50, the organic phase system was added to the aqueous phase system for emulsification and dispersion. The emulsification and dispersion were carried out using a stator-rotor type emulsifying 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 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 h to obtain a single-wall phase-change temperature-regulating microcapsule dispersion with the core material as the core and polyurethane as the wall. The particle size D90 of the single-wall phase-change temperature-regulating microcapsules was 1.439 μm;

[0134] Under the conditions of a temperature of 50 °C and a rotation speed of 650 r / min, gelatin with a mass ratio of 1:1 to the core material contained in the single-wall phase-change temperature-regulating microcapsule dispersion was added, stirred and dissolved, and the pH value was adjusted to 6.0 with acetic acid. Then, gum arabic with a mass ratio of 1.2:1 to gelatin was added for complex coacervation reaction to obtain a suspension; then the suspension was cooled to 15 °C, transglutaminase accounting for 10% of the mass of gelatin was added, and the pH value was adjusted to 7.5 with sodium hydroxide for a cross-linking reaction for 90 min to obtain a double-wall phase-change temperature-regulating microcapsule dispersion, where 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 subjected to spray drying, water washing, and secondary spray drying to obtain highly clean phase-change temperature-regulating microcapsules. The feed temperature of the spray drying was 135 °C, the discharge temperature was 90 °C, and the air volume was 5.0 m 3 / h;

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

[0137] The pulp with an average degree of polymerization of 1000, a content of alpha-cellulose of 96 wt.%, and an ash content of 0.10 wt.% was pulverized, and then added to a cellulose enzyme activation solution with a pH value of 6 and a temperature of 50 °C for activation. After 60 min of activation, the pH value was adjusted to 12 to end the activation, and pressing was carried out to obtain cellulose pulp with a moisture content of 50 wt.%. The cellulose pulp was added to an alkylimidazolium ionic liquid (cation: butyl, anion: CH3COO-), and a cellulose spinning dope was obtained using a thin-film evaporator, where the mass fraction of cellulose was 13%. The temperature of the cellulose spinning dope was maintained at 98 °C and filtered for standby;

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

[0139] The phase change temperature regulating microcapsules were added to an aqueous solution of an alkylimidazole-based ionic liquid with a concentration of 50 wt.% (the cation is butyl and the anion is CH3COO-), and dispersion was carried out by the dual action of strong stirring dispersion and ultrasonic-assisted dispersion. The rotation speed of the strong stirring dispersion was 3500 r / min, and the power of the ultrasonic-assisted dispersion was 450 W. Dispersion was carried out until the droplet size reached D97 = 2.168 μm, thus obtaining the phase change temperature regulating microcapsule dispersion;

[0140] (4) Preparation of high enthalpy phase change temperature regulating Lyocell fiber:

[0141] According to the mass of the phase change temperature regulating microcapsules contained in the phase change temperature regulating microcapsule dispersion system accounting for 80% of the mass of cellulose in the cellulose spinning dope, the cellulose spinning dope and the phase change temperature regulating microcapsule dispersion system were mixed and degassed using a single-screw extruder to obtain a blended spinning dope. The temperatures of the feeding section, melting section, and head section of the single-screw extruder were 105 °C, 110 °C, and 120 °C respectively, the screw rotation speed was 100 r / min, and the vacuum degree was -0.05 MPa;

[0142] The above-mentioned blended spinning dope was spun, and then subjected to drawing, washing, bleaching, first drying, plasma etching, adsorption of functional additives, oiling, cutting, second drying, irradiation crosslinking, and fine opening of cotton in sequence to obtain high enthalpy phase change temperature regulating Lyocell fiber;

[0143] Among them, dry-jet wet spinning was used for spinning. After the blended spinning dope was metered by a metering pump and extruded through a spinneret, it was spun and formed in a coagulation bath. The spinning speed was 50 m / min, the air gap layer adopted a side-blowing method, the air gap layer length was 30 mm, the air gap temperature was 25 °C, and the relative humidity was 60%; the coagulation bath was an aqueous solution of an alkylimidazole-based ionic liquid with a concentration of 23.0 wt.% (the cation is butyl and the anion is CH3COO-), and the temperature was 22 °C;

[0144] Drawing was carried out using a five-roll drawing machine;

[0145] Washing was carried out by circulating and spraying deionized water, with a temperature of 75 °C and a pressure of 0.2 MPa;

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

[0147] The first drying adopted a drying cylinder mode and hot air drying. The fiber tow was continuously wound around the drying cylinder, and the drying temperature was 115 °C;

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

[0149] Functional adjuvant adsorption is carried out using an aqueous solution mixture of algal polysaccharide, chlorogenic acid and acrylic acid, where the concentration of algal polysaccharide is 10 wt.%, the concentration of chlorogenic acid is 15 wt.%, the concentration of acrylic acid is 8 wt.%, the pH value is 6.8, and the temperature is 80 °C;

[0150] Oil application is carried out by circulating spray using an oil bath with a concentration of 7.0 g / L at a temperature of 75 °C;

[0151] The second drying is carried out by vacuum drying at a temperature of 38 °C until the fiber moisture regain is 10.8%;

[0152] The accelerator energy for irradiation crosslinking is 1.5 MeV, at room temperature, in an air atmosphere, with an absorbed dose of 50 kGy.

[0153] Comparative Example 1

[0154] The difference between this example and Example 1 is only that in step (1), when preparing the core material of the microcapsule, n - hentriacontane is not added, and n - nonadecane with the same mass is used to replace it, that is: a mixture of n - octadecane and n - nonadecane with 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 min for mixing and melting to obtain the core material of the microcapsule. The remaining steps are the same as those in Example 1.

[0155] Comparative Example 2

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

[0157] Comparative Example 3

[0158] The difference between this example and Example 1 is only that in step (3), when preparing the phase - change temperature - regulating microcapsule dispersion system, a high - concentration aqueous solution of NMMO is used as the dispersion solvent, that is: the phase - change temperature - regulating microcapsules are added to an aqueous solution of NMMO with a concentration of 80 wt.%, and dispersed by the dual action of strong stirring dispersion and ultrasonic - assisted dispersion. The rotation speed of strong stirring dispersion is 3000 r / min, the power of ultrasonic - assisted dispersion is 450 W, and dispersed until the droplet size reaches D97 = 1.973 μm to obtain the phase - change temperature - regulating microcapsule dispersion. The remaining steps are the same as those in Example 1.

[0159] The phase change temperature-regulating Lyocell fibers prepared in each example and comparative example were subjected to performance tests. Among them, the dry breaking strength and wet breaking strength were tested according to the standard GB / T 14337-2008; the phase change melting temperature, melting enthalpy, phase change crystallization temperature, and crystallization enthalpy were tested according to the standard FZ / T 50061-2023; the inhibition rate of Escherichia coli and the inhibition rate of Candida albicans were tested according to the standard GB / T 20944.3-2008; the reduction rate of ammonia 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 the phase change temperature-regulating Lyocell fibers prepared in each example and comparative example

[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 change melting temperature, °C 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 change crystallization temperature, °C 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 Inhibition rate against Escherichia coli, % 81.8 83.9 86.7 81.6 81.5 81.2 Inhibition rate against Candida albicans, % 80.6 83.1 86.0 80.7 80.4 80.8 Reduction rate of ammonia, % 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 fibers prepared by the present invention have good phase change temperature regulation, antibacterial, and ammonia elimination functions. Its dry breaking strength ≥ 3.5 cN / dtex, wet breaking strength ≥ 2.3 cN / dtex, phase change melting temperature 19.5 - 40.8 °C, melting enthalpy 29.5 - 79.6 J / g, phase change crystallization temperature 26.3 - 17.9 °C, crystallization enthalpy 28.9 - 79.7 J / g, inhibition rate of Escherichia coli ≥ 81%, inhibition rate of Candida albicans ≥ 80%, reduction rate of ammonia ≥ 79%. And with the increase of the addition amount of the phase change temperature-regulating microcapsules, the melting enthalpy and crystallization enthalpy of the fibers increase correspondingly, but the dry breaking strength and wet breaking strength of the fibers basically remain unchanged, indicating that the double-wall phase change temperature-regulating microcapsule structure of the present invention has little influence on the strength of the fibers.

[0163] In Comparative Example 1, n-heneicosane is not added to the core material of the microcapsules, resulting in a significant decrease in the melting temperature and crystallization temperature of the fibers, and the other properties are not much different. This is because the crystallization peak temperature of n-octadecane is 25.4 °C, the crystallization peak temperature of n-nonadecane is 26.4 °C, and the crystallization peak temperature of n-heneicosane is 35.9 °C. The lack of n-undecane and its crystallization core effect results in a lower phase change melting temperature range, a larger decrease in the phase change crystallization temperature compared with the theoretical value, and a supercooling phenomenon.

[0164] In Comparative Example 2, polyurethane single-wall phase change temperature-regulating microcapsules are used, and the melting enthalpy and crystallization enthalpy of the fibers decrease. This is because the microcapsules will be damaged due to friction, shear, etc. during the spinning process, resulting in the loss of a small part of the phase change material, thus affecting the temperature regulation effect of the fibers; in addition, the dry breaking strength and wet breaking strength of the fibers also decrease significantly. This is because the compatibility of polyurethane and cellulose is lower than that of the gelatin-arabic gum product, and the spherical microcapsules cannot form a cross-linked structure with the fibers during the spinning process, thus affecting the strength of the fibers.

[0165] Comparative Example 3 uses a high-concentration fiber solvent system 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 all decrease because the high-concentration fiber solvent system promotes the dissolution of the outer capsule wall, thereby affecting the protective and cross-linking effects 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: The 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 evenly to obtain an organic phase system; an emulsifier is added to water and mixed evenly 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 capsule wall phase change temperature regulating microcapsule dispersion; Adding gelatin and gum arabic to a dispersion of single-wall phase-change temperature-regulating microcapsules, stirring and mixing to form a suspension, and then adding a curing agent to perform 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 into an aqueous solution of a cellulose solvent having a concentration of 30-50 wt.%, and dispersed evenly to obtain a phase-change temperature-regulating microcapsule dispersion system; (4) Preparation of high enthalpy phase change temperature regulating lyocell fiber: 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, and then spinning and post-treatment are performed to obtain a high enthalpy phase change temperature regulating lyocell fiber; The cellulose solvent is NMMO or an ionic liquid.

2. The method for preparing high enthalpy phase change temperature regulating lyocell fiber according to claim 1, characterized in that: In step (1), the mass ratio of n-octadecane, n-nonadecane and n-heneicosane is 50:(35-40):(10-15).

3. 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%.

4. 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.

5. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: 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.

6. The method for preparing high enthalpy phase-change temperature-regulating lyocell fiber according to claim 1, characterized in that: In step (2), the cellulose pulp is obtained by activating pulp having 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 has a moisture content of 50-60 wt.%; the mass fraction of cellulose in the cellulose spinning stock solution is 9.5-13.0%.

7. 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%.

8. 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 stock 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 stock solution.

9. A high enthalpy phase change temperature regulating lyocell fiber prepared by the preparation method according to any one of claims 1 to 8, 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%.