Preparation method of high-enthalpy ultra-low supercooled lyocell formaldehyde-free phase change microcapsule
By preparing aldehyde-free phase change microcapsules with a particle size of less than 10 μm, the problems of undercooling and spinneret blockage in wet spinning were solved, achieving high enthalpy, low undercooling and environmentally friendly phase change microcapsules, thus improving the stability and thermal response efficiency of the spinning process.
Patent Information
- Application Number
- CN202511608789.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-01-23
AI Technical Summary
The phase change microcapsules prepared by the existing wet spinning method suffer from supercooling, resulting in low energy storage efficiency. Furthermore, the microcapsules are prone to clogging the spinneret orifices, affecting the continuity of the spinning process and fiber strength.
Styrene-maleic anhydride copolymer was used as an emulsifier and acrylate was used as a wall material. Formaldehyde-free phase change microcapsules with a particle size of less than 10 μm were prepared through emulsification and polymerization reactions. This ensured that the microcapsules were uniformly dispersed in the fiber, reduced supercooling and improved thermal response speed.
Phase change microcapsules with high enthalpy and ultra-low supercooling were achieved, which improved the stability of the spinning process and fiber strength, increased thermal response speed and heat exchange efficiency, and met the standards for environmentally friendly textiles.
Smart Images
Figure CN121372225A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microcapsule preparation technology, and in particular relates to a method for preparing high enthalpy value, ultra-low supercooled lyocell aldehyde-free phase change microcapsules. Background Technology
[0002] Phase change fiber (PCM), also known as thermoregulating fiber or smart temperature-regulating fiber, is a functional material composed of PCM and a fiber matrix. Its core mechanism lies in the fact that when the ambient temperature fluctuates, the PCM within the fiber absorbs / releases high-density latent heat through a solid-liquid phase change process (or solid-solid phase change), achieving dynamic bidirectional regulation of the surface temperature and forming a stable "thermal buffer platform." There are two methods for preparing PCM using spinning: one is to directly mix the PCM with the fiber matrix, and the other is to first encapsulate the PCM and then blend it with the matrix. Compared to direct mixing, microencapsulation allows for more uniform dispersion of PCM within the polymer matrix, and the microcapsule encapsulation structure effectively prevents PCM leakage, thus significantly improving the fiber's durability and washability. Currently, electrospinning dominates the preparation technology of PCM. However, this method has significant limitations: the resulting fibers are usually randomly arranged, leading to weak mechanical properties, and the fiber orientation is difficult to precisely control. In comparison, wet spinning has the advantage of mild operating conditions and shows better applicability in the field of phase change fiber preparation.
[0003] Currently, the wet spinning method for preparing phase change microcapsule lyocell fibers (PCM-Lyocell) has demonstrated significant advantages in industrial applications. This process utilizes an N-methylmorpholine-N-oxide (NMMO) closed-loop solvent system, achieving a solvent recovery rate exceeding 99.7%, exhibiting excellent environmental friendliness. Simultaneously, microcapsule encapsulation technology enables effective temperature regulation and effectively prevents PCM leakage. The high wet strength (85% of dry strength) and excellent moisture absorption (50% higher than cotton) of lyocell fibers, combined with the microcapsules, endow the material with both wash resistance and a comfortable feel. Despite process challenges such as controlling the viscosity of the spinning solution, the technology has become the preferred solution for large-scale production of phase change fibers due to cost reduction through domestic production and rapid capacity expansion, and is widely used in sportswear, medical dressings, and other fields.
[0004] Supercooling is a major challenge for phase change microcapsules in practical applications. This means that the actual crystallization temperature of a liquid substance is lower than the theoretical crystallization temperature, which causes latent heat to be released at a lower or wider temperature range, which is not conducive to energy storage. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing high enthalpy ultra-low supercooled lyocell aldehyde-free phase change microcapsules, which optimizes the supercooling phenomenon of phase change microcapsules.
[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:
[0007] A method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules includes the following steps:
[0008] Preparation of emulsifier: Sodium hydroxide was added to styrene-maleic anhydride copolymer (SMA) resin, and the SMA emulsifier was obtained by hydrolysis;
[0009] Preparation of aqueous phase: Mix SMA emulsifier with deionized water and adjust the pH to acidic to obtain aqueous phase A;
[0010] Preparation of the oil phase: Oil phase B was prepared using n-octadecane as the core material and EGDMA, BDDMA, MMA and PETRA as the wall material;
[0011] Emulsification and dispersion: Aqueous phase A and oil phase B are mixed and then emulsified to form a stable O / W emulsion;
[0012] Polymerization reaction: AIBN initiator was added to the above emulsion, and the phase change microcapsule suspension was prepared by reaction.
[0013] Beneficial effects:
[0014] (1) The particle size obtained by the method described in this disclosure is much smaller than the spinneret diameter commonly used in lyocell spinning. This greatly reduces the risk of microcapsules clogging the spinnerets, improves the continuity and stability of the spinning process, reduces the breakage rate, and increases production efficiency. The small-diameter microcapsules are dispersed in the fiber as "impurities," and their size is more in line with the fiber diameter (usually 10-20 micrometers). This reduces stress concentration points caused by large particles, lowers the risk of fiber breakage during spinning and subsequent processing (such as stretching), and helps to improve fiber strength and yield.
[0015] (2) The small particle size allows for more uniform dispersion within the fiber matrix, making it less prone to forming large defects or stress concentration sources. This helps maintain the excellent mechanical properties of lyocell fibers (such as strength and modulus) and avoids a significant decrease in mechanical properties due to the addition of functional particles. The small particle size provides a larger specific surface area, which theoretically may help with interfacial bonding with the lyocell cellulose matrix (although this also depends on the compatibility of the microcapsule shell), potentially benefiting mechanical properties.
[0016] (3) A smaller degree of supercooling means that PCM can relatively easily initiate the crystallization (solidification exothermic) process when cooled to near its theoretical freezing point. This significantly improves the thermal response speed and efficiency of the material in practical applications, enabling it to release latent heat closer to the set temperature and provide more timely and effective insulation or temperature buffering. Reducing the degree of supercooling can reduce the time the material spends in the supercooled liquid state and unnecessary temperature fluctuations, making the phase change process closer to the ideal state, thereby making fuller use of the latent heat of PCM.
[0017] (4) Smaller particle size allows for more uniform dispersion in the spinning solution (viscose) and achieves a uniform distribution within the final fiber. This ensures consistent thermal regulation throughout the entire fiber and fabric, avoiding localized overheating or undercooling areas. For the same mass or volume, smaller particle size provides a larger total surface area, resulting in higher heat exchange efficiency between PCM and the external environment (or the microenvironment of human skin), which helps to respond to temperature changes more quickly.
[0018] (5) Compared with polyurea, polyurethane, and melamine resin, acrylate has the following significant advantages as a microcapsule wall material: No formaldehyde release. Melamine resin (melamine-formaldehyde resin) requires formaldehyde in its synthesis process, and residual formaldehyde is easily released (especially in high-temperature environments), failing to meet the requirements for environmentally friendly textiles (such as formaldehyde-free finishing). Acrylate polymerization is a formaldehyde-free process, meeting stringent environmental standards (such as OEKO-TEX®, GB 18401). Low-toxicity monomers. Polyurethane synthesis commonly uses isocyanate monomers (which are irritating), while acrylate monomers are less toxic and safer. Acrylates can achieve controllable design from flexible to rigid by selectively adjusting the glass transition temperature (Tg). Furthermore, acrylate monomers have better acid and alkali resistance than melamine resin (which is easily hydrolyzed in alkaline environments), making them suitable for dyeing and finishing processes. Acrylates have good bonding strength with fibers (cotton, polyester, etc.), improving the fastness of microcapsules on fabrics. They are more suitable for preparing lyocell spinning microcapsules.
[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 DSC curves for n-octadecane and phase change microcapsules;
[0022] Figure 2 TG curves for high enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules;
[0023] Figure 3 Particle size distribution of high enthalpy ultra-low supercooled lyocell aldehyde-free phase change microcapsules;
[0024] Figure 4 Comparison of phenolic yellowing in high enthalpy ultra-low supercooled Lyocell aldehyde-free phase change microcapsules. Detailed Implementation
[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] This embodiment provides a method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules, including the following steps:
[0027] S1: Preparation of emulsifier
[0028] Weigh 10 parts by mass of styrene-maleic anhydride copolymer (SMA) resin, add 3 parts by mass of sodium hydroxide solution, stir and hydrolyze at 80 °C for 5 hours, and cool to room temperature to obtain SMA emulsifier.
[0029] S2: Prepare the aqueous phase
[0030] Dissolve 120 parts by weight of the SMA emulsifier in deionized water, add an appropriate amount of citric acid solution to adjust the pH to 4.0-5.0 and stir for 10 minutes to obtain a uniformly acidic aqueous phase, denoted as solution A, with a preferred pH value of 4.5.
[0031] S3: Preparation of oil phase
[0032] Weigh out 80 parts by mass of n-octadecane, 20 parts by mass of ethylene glycol dimethacrylate (EGDMA), and 1 part by mass of 1,4-butanediol diacrylate (BDDMA). Mechanically stir at 1000 r / min for 30 minutes. During stirring, slowly add 6.5 parts by mass of methyl methacrylate (MMA) and 1.5 parts by mass of pentaerythritol tetraacrylate (PETRA). Continue stirring at 60 °C until homogeneous to obtain oil phase B.
[0033] S4: Emulsifying and dispersing
[0034] The aqueous phase A and oil phase B are mixed in a ratio of 1:(1 to 1.5) and emulsified for 10 to 30 minutes using a high-speed emulsifier at a speed of 9000 r / min to obtain an O / W type emulsion with uniform droplet size and stable distribution.
[0035] S5: Polymerization reaction
[0036] 0.8 parts by mass of azobisisobutyronitrile (AIBN) were added to the above emulsion as a free radical initiator, and the reaction was carried out at a constant temperature of 80-95℃ for 5-24 hours to form a high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsule suspension.
[0037] In some implementations, the crosslinking monomer can be replaced according to system performance requirements:
[0038] EGDMA can be replaced with 1,6-hexanediol diacrylate (HDDA) or polyethylene glycol diacrylate (PEGDA).
[0039] PETRA can be replaced with pentaerythritol triacrylate (PETA), 1,4-butanediol diacrylate (BDDA), or trimethylolpropane triacrylate (TMPTA).
[0040] The above substitutions will not significantly affect emulsion stability and polymerization reaction, but can be flexibly selected and optimized according to the target phase change temperature, microcapsule shell density and toughness requirements.
[0041] Those skilled in the art should understand that the specific technical features, proportioning parameters, and process conditions described in the embodiments of this invention are preferred examples and not limitations thereof. Without departing from the core concept of this invention, the types of raw materials, mass fractions, reaction conditions, and monomer substitution relationships (e.g., substitutions between EGDMA, HDDA, and PEGDA, and between PETRA, PETA, BDDA, and TMPTA) in each embodiment can be combined or appropriately adjusted according to actual needs. Any combination of the above technical features that achieves the same or similar technical effects should be considered to fall within the protection scope of this invention.
[0042] To verify the performance of the high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules prepared in this invention, several physicochemical property tests and evaluations were conducted on the obtained samples. The test methods and results are as follows:
[0043] I. Differential Scanning Calorimetry (DSC) Test;
[0044] The DSC curves of high enthalpy ultra-low supercooled lyocell aldehyde-free phase change microcapsules and n-octadecane are shown below. Figure 1 As shown;
[0045] The melting temperature of n-octadecane is 30.06 ℃, the crystallization temperature is 22.99 ℃, the enthalpy of melting is 233.49 J / g, and the enthalpy of crystallization is 233.66 J / g. The melting temperature of the microcapsules is 28.95 ℃, and the crystallization temperature is 24.78 ℃, which is close to the phase change temperature of octadecane. This indicates that the heat storage performance of the phase change microcapsules is provided by octadecane, confirming that n-octadecane is successfully encapsulated by the acrylic resin polymer. The obtained phase change microcapsules have a melting enthalpy of 192.74 J / g and a crystallization enthalpy of 189.16 J / g, exhibiting excellent heat storage performance. The encapsulation rate is 82.55%, indicating a high utilization rate of the core material n-octadecane, and the synthesized high-enthalpy ultra-low supercooled lyocell aldehyde-free phase change microcapsules have good phase change heat storage capacity.
[0046] II. Heat Resistance Test
[0047] To ensure stability under the thermal processing conditions of lyocell spinning, phase change microcapsules must possess excellent thermal shock resistance. Thermogravimetric analysis results of the high enthalpy, ultra-low supercooling, formaldehyde-free lyocell phase change microcapsules developed in this study confirm this.
[0048] like Figure 2 As shown. Its thermogravimetric curve shows obvious two-stage mass loss: the first stage of weight loss is due to the continuous volatilization of n-octadecane inside the microcapsule; the second stage of weight loss begins with the decomposition of the capsule wall material, and the decomposition process does not end until 495 °C. This result fully demonstrates that: (1) the acrylate capsule wall material has excellent thermal stability; (2) n-octadecane has been successfully encapsulated, forming an aldehyde-free phase change microcapsule with high enthalpy and ultra-low supercooling characteristics.
[0049] III. Particle Size Analysis
[0050] like Figure 3 As shown, the high enthalpy, ultra-low supercooled, formaldehyde-free lyocell phase change microcapsules prepared by the method described herein exhibit an approximately normal particle size distribution, ranging from 0.32 μm to 1.69 μm. Approximately 91.84% of the microcapsule particles are concentrated within this narrow range of 0.50 μm to 2.00 μm. This result significantly demonstrates the high concentration of microcapsule particle size distribution and the excellent uniformity of particle size.
[0051] IV. Yellowing Test
[0052] To evaluate the ability of microencapsulated fabrics to resist yellowing caused by phenolic compounds, phenolic yellowing tests were conducted on the samples in accordance with the national standard GB / T29778-2013 "Textiles - Color Fastness Tests: Evaluation of Potential Phenolic Yellowing".
[0053] After testing, the degree of yellowing of the sample is evaluated using one of the following two methods:
[0054] (1) Visual rating: The rating shall be conducted using the gray scale for assessing staining under the standard observation and lighting conditions specified in GB / T6151.
[0055] (2) Instrument rating: The instrument shall be evaluated in accordance with the method specified in FZ / T01023.
[0056] Test results: such as Figure 4 The area shown in the black dashed box indicates that the white woven fabric treated with the phase change material (PCM) of the present invention has a yellowing level of 4-5 in the printing phenol yellowing test.
[0057] The results indicate that the fabric treated with microcapsules has excellent resistance to phenolic yellowing, and its color fastness meets high standards.
[0058] V. Formaldehyde content test
[0059] Sample preparation and exposure:
[0060] (1) Take about 50 g of deionized water and place it in an Erlenmeyer flask. Weigh about 1 g of nonwoven fabric sample that has been impregnated with PCM stock solution, wrap it with formaldehyde-free cotton thread to fix it, and suspend it above the liquid surface in the Erlenmeyer flask (ensure that the sample does not come into contact with the liquid).
[0061] (2) High temperature treatment: Seal the conical flask and place it in a constant temperature oven, and heat it for 4 hours at (65±1)℃.
[0062] (3) Sampling of absorption solution: Remove the conical flask and cool it to room temperature. Transfer 5 mL of deionized water from the conical flask into a clean test tube.
[0063] (4) Color reaction: Add 5 mL of Nessler's reagent to the above test tube and mix well. Place the test tube in a constant temperature water bath and heat the reaction at (60±1)℃ for 3 minutes.
[0064] (5) Colorimetric determination: Pour the reacted solution into a cuvette. Using a blank reagent (5 mL deionized water + 5 mL Nessler's reagent, heated in the same water bath) as a reference, use a spectrophotometer to measure the absorbance at the characteristic wavelength (usually ~420 nm) corresponding to the Nessler's reagent.
[0065] Test principle: Under high temperature conditions, formaldehyde that may be present in the fabric is easily volatilized and dissolved in the deionized water inside the conical flask. Therefore, by measuring the formaldehyde content in this absorbent (after Nessler's reagent color development), the formaldehyde release of the fabric under simulated high temperature conditions can be effectively assessed.
[0066] Formaldehyde content = (absorbance - 0.052) / 0.129 * 50
[0067] Test results: The absorbance is 0.091 and the formaldehyde content is 15.12, which are extremely low values, indicating that it is a formaldehyde-free PCM finishing agent.
[0068] Understandably, the main factors influencing supercooling include particle diameter, the type of nucleating agent, and the amount of nucleating agent added. Adding nucleating agents is a common method to reduce supercooling. However, different types and concentrations of nucleating agents generally have different effects on different materials. Therefore, it is necessary to find the optimal balance between the type and concentration of the nucleating agent to achieve the best effect in suppressing supercooling.
[0069] Generally speaking, for phase change material capsules with an average particle size of less than 10 μm, the phase change temperature and phase change heat of the capsule do not change with the particle size, but the crystallization peak changes significantly, and the supercooling phenomenon intensifies as the particle size decreases. The phase change microcapsules of lyocell fiber need to meet the following core conditions: (1) the shell material needs to be heat resistant to withstand the high temperature dissolution environment (80-120 ℃) of the NMMO solvent system; (2) the particle size of the phase change microcapsules needs to be strictly controlled below 5 μm to avoid clogging the spinning pores; (3) the core material has a high phase change enthalpy and is compatible with the cellulose matrix. The main technical difficulty at present is that the microcapsules are prone to agglomeration in the spinning solution, which leads to an increase in the fiber breakage rate, and it is difficult to simultaneously meet the requirements of high enthalpy, low supercooling, uniform particle size of less than 5 μm, and formaldehyde-free. The phase change microcapsules of lyocell fiber in this invention have a particle size D100 = 1.689 μm, and the supercooling is only 4.17 ℃ without the addition of nucleating agents. The enthalpy value is 192.74 J / g, and it does not contain formaldehyde. The process is simpler and easier to obtain than the process of adding nucleating agents.
[0070] The above verification shows that the preparation method described in this disclosure has the following advantages;
[0071] 1. High enthalpy and low undercooling: The phase change enthalpy of the core material n-octadecane is as high as 192.74 J / g, and the undercooling is only 4.17 ℃ without the addition of nucleating agent, which is significantly better than the existing phase change material system.
[0072] 2. Controllable and uniform particle size distribution: The microcapsule particle size D100 is 1.689 μm, which is much smaller than the spinneret orifice diameter of Lyocell spinning, effectively avoiding spinneret blockage and improving the continuity and stability of the spinning process.
[0073] 3. Excellent thermal stability: The capsule wall maintains structural integrity up to 495 ℃ and can withstand the high-temperature processing environment of the NMMO solvent system, meeting the requirements of industrial lyocell fiber preparation.
[0074] 4. Excellent environmental performance: The microcapsule system contains no free formaldehyde, and the formaldehyde release of the fabric after treatment is extremely low, meeting the requirements of international environmental protection textile standards.
[0075] 5. Excellent anti-yellowing properties: Textiles treated with microcapsules achieve a yellowing level of 4-5 and can maintain excellent appearance quality for a long time.
[0076] In summary, the high enthalpy ultra-low supercooled lyocell aldehyde-free phase change microcapsules provided by this invention not only achieve a balance between high energy efficiency and environmental friendliness in structural design, but also exhibit significant advantages in process adaptability, thermal stability, and end-application performance, and have good prospects for industrialization.
[0077] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0078] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules, characterized in that, Includes the following steps: Preparation of emulsifier: Sodium hydroxide was added to styrene-maleic anhydride copolymer (SMA) resin, and the SMA emulsifier was obtained by hydrolysis; Preparation of aqueous phase: Mix SMA emulsifier with deionized water and adjust the pH to acidic to obtain aqueous phase A; Preparation of oil phase: Using n-octadecane as the core material and EGDMA, BDDMA, MMA and PETRA as the wall material, oil phase B is prepared by thorough mixing; Emulsification and dispersion: Aqueous phase A and oil phase B are mixed and then emulsified to form a stable O / W emulsion; Polymerization reaction: AIBN initiator was added to the above emulsion, and the phase change microcapsule suspension was prepared by reaction.
2. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, The emulsifier is prepared as follows; Weigh out SMA resin and sodium hydroxide solution in a mass ratio of 10:3, stir and hydrolyze at 80 °C for 5 hours, and then cool to room temperature to obtain SMA emulsifier.
3. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, The pH was adjusted to 4.0–5.
0.
4. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, The steps for preparing the oil phase include: 80 parts by mass of n-octadecane, 20 parts by mass of EGDMA, and 1 part by mass of BDDMA were mechanically stirred at 1000 r / min for 30 minutes. During the stirring process, 6.5 parts by mass of MMA and 1.5 parts by mass of PETRA were added dropwise, and the mixture was stirred and mixed evenly at 60 °C to obtain oil phase B.
5. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, The emulsification and dispersion steps include: The aqueous phase A and oil phase B are mixed in a ratio of 1:(1 to 1.5), and emulsified in an emulsifier at a speed of 9000 r / min for 10 to 30 minutes.
6. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, The polymerization reaction steps include: 0.8 parts by weight of AIBN were added to the emulsion as a free radical initiator, and the reaction was carried out at 80-95°C for 5-24 hours.
7. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, EGDMA can be replaced with HDDA or PEGDA.
8. The method for preparing high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsules according to claim 1, characterized in that, PETRA can be replaced with PETA, BDDA, or TMPTA.
9. A high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsule, characterized in that, The phase change microcapsules are prepared by the method described in any one of claims 1-8.
10. A high-enthalpy, ultra-low supercooled lyocell aldehyde-free phase change microcapsule, characterized in that, The phase change microcapsules have a particle size of 0.32 μm to 1.69 μm.