PCM phase-change nano microcapsule temperature-adjusting composite chemical fiber and preparation method thereof

Abstract

The invention discloses a PCM phase-change nano microcapsule temperature-adjusting composite chemical fiber and a preparation method thereof. The preparation method of the PCM phase-change nano microcapsule temperature-adjusting composite chemical fiber comprises the following steps: S1, material preparation: weighing a combination of PCM phase-change nano microcapsules and PE as a core material, controlling the weight ratio of the PCM phase-change nano microcapsules to the PE to be 1: (0.5-2), weighing a combination of one or more of PA, PP and PET as a skin material, and controlling the weight ratio of the core material to the skin material to be 1: (0.5-1.5); s2, melting and plasticizing: melting and granulating the core material to obtain phase-change modified master batches, and respectively melting and extruding the phase-change modified master batches and the skin material to obtain molten master batches and a molten skin material; s3, distribution forming: performing coaxial internal and external micro-fluidic distribution on the molten master batch and the molten skin material, and performing composite spinning forming; the prepared PCM phase-change nano microcapsule temperature-adjusting composite chemical fiber is good in temperature-adjusting effect and excellent in durability.

Description

Technical Field

[0001] The present invention relates to the technical field of fibers, especially the technical field of temperature-regulating composite chemical fibers. Background Art

[0002] With the continuous increase in people's demand for functional textiles, fibers with temperature-regulating functions have gradually become a research hotspot in the textile field; traditional textiles mainly achieve heat preservation or breathability functions by adjusting the physical structure of fibers (such as porosity and thickness), such as a preparation method of a high-porosity material with heat insulation and heat preservation as disclosed in Publication No. CN114059378A; however, these methods often have difficulty providing effective temperature regulation under extreme climate conditions.

[0003] A phase change material (PCM - Phase Change Material) is a thermal energy storage material that can utilize the heat absorption and heat release of a substance during the phase change process (solid - liquid - solid) to store and release thermal energy; specifically, on the one hand, the phase change material will melt and absorb heat when the external temperature rises to the melting point of the phase change material, and on the other hand, it will solidify and release heat when the external temperature drops to the freezing point of the phase change material, so as to achieve the purpose of controlling the environmental temperature and conducting heat exchange.

[0004] Introducing PCM into textiles can significantly improve the thermal comfort of textiles, making them provide a cooling sensation in a hot environment and enhancing the heat preservation effect in a severe cold environment, such as an adjustable-temperature intelligent fiber as disclosed in Publication No. CN107761385A; however, the method of directly coating PCM on the fiber surface in the form of a coating not only damages the properties of fibers such as breathability and moisture permeability (which is likely to have a negative impact on thermal comfort), is not convenient for later production and finishing, but also PCM may gradually fall off during the washing, friction or stretching process of textiles due to the weak binding force with the fiber surface (the temperature-regulating function of textiles will significantly decline with the increase in the number of uses, reducing the service life of the product). Summary of the Invention

[0005] The purpose of the present invention is to solve the problems in the prior art and propose a PCM phase change nano-microcapsule temperature-regulating composite chemical fiber and its preparation method, which have good temperature-regulating effects and excellent durability.

[0006] To achieve the above purpose, the present invention proposes a preparation method of a PCM phase change nano-microcapsule temperature-regulating composite chemical fiber, including the following steps: S1. Material preparation: Weigh PCM phase change nano-microcapsules and PE to form a core material, and control the weight ratio of PCM phase change nano-microcapsules to PE at 1:0.5 - 2. Weigh one or a combination of PA, PP, and PET as the skin material, and control the weight ratio of the core material to the skin material at 1:0.5 - 1.5; S2. Melting and plasticizing: Melting and granulating the core material to obtain the phase change modified masterbatch, and separately melting and extruding the phase change modified masterbatch and the skin material to obtain the molten masterbatch and the molten skin material; S3. Dispensing and forming: Coaxially and microfluidically dispensing and compound spinning and forming the molten masterbatch and the molten skin material.

[0007] Preferably, in step S1, the particle size of the PCM phase change nano - microcapsules is 500 - 700 nm and the enthalpy value is 180 - 200 J / g. The PCM phase change nano - microcapsules use silica as the wall material and n - octadecane as the core material.

[0008] Preferably, in step S2, use an extrusion granulator to melt - granulate the core material and protect it with an inert atmosphere. The core material needs to be melted to 150 - 200 °C. Use a twin - screw extruder to synchronously melt - extrude the phase change modified masterbatch and the skin material and protect it with an inert atmosphere. The phase change modified masterbatch needs to be melted to 180 - 210 °C, and the skin material needs to be melted to 200 - 220 °C.

[0009] Preferably, in step S3, use a microfluidic chip for microfluidic dispensing, control the core layer channel temperature at 180 - 210 °C, and control the sheath layer channel temperature at 190 - 220 °C.

[0010] Preferably, in step S3, control the core layer melt pressure in the core layer channel at 10 - 20 MPa (i.e., control the screw speed at 10 - 30 rpm), control the sheath layer melt pressure in the sheath layer channel at 5 - 15 MPa (i.e., control the screw speed at 5 - 20 rpm), keep the flow rate ratio of the core layer melt to the sheath layer melt at 1:2 - 5, and at the same time, through pre - pressurization, make the sheath layer melt pressure at the sheath layer channel inlet 2 - 8% higher than the core layer melt pressure at the core layer channel inlet.

[0011] Preferably, in step S3, the core layer channel diameter is 180 - 220 μm, the sheath layer channel annulus width is 40 - 60 μm, and at the same time, apply a DC electric field to compress the fiber sheath layer thickness to less than 10 μm at the sheath layer channel outlet.

[0012] Preferably, in step S3, use a spinneret to spin - draw to achieve compound spinning, control the aspect ratio of the spinneret at 18 - 22:1, and control the spinneret draw ratio at 3 - 10.

[0013] Preferably, in step S3, a multi-stage air ring with a maximum temperature not exceeding 220°C and gradually decreasing to room temperature is used for side blowing during spinning, and the wind speed is controlled at 0.2 - 0.5 m / s. In addition, during winding, the winding linear speed can be controlled at 5 - 20 m / min (corresponding to a fiber diameter of 10 - 50 μm), the tension control accuracy is ±0.1 N, and the winding tension is controlled at 0.5 - 2.0 N (dynamically adjusted according to the fiber modulus to avoid filament breakage).

[0014] Preferably, the method further includes the following steps: Step S4, post-treatment: When the composite spinning is completed, the composite fiber is subjected to heat setting treatment and plasma treatment in sequence.

[0015] The PCM phase change nano-microcapsule temperature-regulating composite chemical fiber is manufactured by the above preparation method, with an enthalpy value of 10 - 50 J / g and a breaking strength of 2.1 - 3.5 cN / dtex.

[0016] Advantages of the present invention: 1) In the present invention, PCM phase change nano-microcapsule particles with a particle size of 500 - 700 nm and an enthalpy value of 180 - 200 J / g are uniformly dispersed in the PE material (the PE material has a relatively high thermal conductivity among current existing chemical fiber materials and also meets the temperature sensitivity of the PCM phase change material). Thus, the PCM phase change material can absorb and release heat at the fastest speed via the PE substrate, maximizing its phase change property. Furthermore, the prepared fiber can achieve the phase change temperature-regulating function within a specific temperature range, enabling the manufactured textiles to utilize the self-energy storage characteristic to improve the comfort of the wearer (on the one hand, the textiles absorb heat through the phase change property in a hot environment to improve the cool feeling, and on the other hand, release heat through the phase change property in a cold environment to enhance the warmth retention effect, ultimately achieving the purpose of providing additional protection under extreme climate conditions); 2) In the present invention, the PCM phase change nano-microcapsule particles are mixed with PE to form the fiber core, and a fiber outer skin composed of one or a combination of several of PA, PP, and PET is added outside the fiber core. Thus, it can effectively prevent the PCM phase change material from gradually falling off during the washing, friction, or stretching process of the textiles, and effectively avoid the problem of difficult additional finishing of the fibers caused by the poor dyeing and finishing properties of PE (using PE as the core layer can maximize the avoidance of the shortcoming of the PE material property); 3) In the present invention, by using pre-pressurization at the sheath layer inlet and adding a fluorinated coating to the double-layer channel in the microfluidic dispensing and interface control link, it can effectively avoid the backflow of the core layer melt, reduce the melt adhesion, and achieve interface stability; 4) By applying a DC electric field at the outlet of the sheath channel of the microfluidic chip in the present invention, the electroviscous effect can be utilized to compress the thickness of the fiber sheath layer to less than 10 μm, reduce the fluctuation of the sheath layer thickness (improve the uniformity and consistency of the fibers), reduce the waste of the sheath layer material (improve the material utilization rate), and increase the proportion of the fiber core layer; 5) By using a multi-stage air ring with a temperature not exceeding 220°C at the highest and then gradually decreasing to room temperature for side blowing during spinning and controlling the wind speed at 0.2 - 0.5 m / s in the present invention, the generation of adhesion phenomenon can be effectively avoided, and the unevenness of the internal stress of the fiber due to sudden cooling can also be effectively prevented; 6) By adding a heat setting treatment step and a plasma treatment step in the later stage of the preparation process in the present invention, the residual stress can be further eliminated and the cleanliness can be improved, and the surface activity of the fiber is also increased (facilitating additional dyeing and finishing and other functional treatments according to requirements).

[0017] The features and advantages of the present invention will be described in detail through examples in conjunction with the accompanying drawings. Description of the Drawings

[0018] Figure 1 is a cross-sectional view of the PCM phase change nano-microcapsule temperature-regulating composite chemical fiber prepared in the example; Figure 2 is a DSC test result graph of the PCM phase change nano-microcapsule temperature-regulating composite chemical fiber prepared in the example; In the figure: 1 - combined core, 11 - PE structure, 12 - PCM phase change nano-microcapsule structure, 2 - PA outer skin. Specific Embodiments

[0019] A preparation method of PCM phase change nano-microcapsule temperature-regulating composite chemical fiber includes the following steps: S1. Material Preparation: Weigh PCM phase change nano-microcapsules and PE as the core material (a low melting point, medium low modulus polymer), and control the weight ratio of PCM phase change nano-microcapsules to PE at 1:1.5. Weigh PA as the skin material (a functionalized medium high melting point material, melting point 160 - 200°C), and control the weight ratio of the core material to the skin material at 1:1. Among them, PE is a widely used plastic with good chemical stability, electrical insulation, and low temperature resistance, and can provide basic strength and durability for fibers in fiber manufacturing; PA, also known as nylon, is a synthetic polymer material with excellent wear resistance, resilience, fatigue resistance, and chemical corrosion resistance, and can effectively improve the strength and wear resistance of textiles; The PCM phase change nano-microcapsules are selected to be microcapsules with silica as the wall material and n-octadecane as the core material, prepared by the sol-gel method with a particle size of 600 nanometers and an enthalpy value of 180 J / g (such nano-scale microcapsules are particularly suitable for spinning); regarding the silica outer wall, first, the thermal stability of silica is extremely high, which can keep the PCM phase change nano-microcapsules in structural integrity in a high-temperature environment (this is particularly important for the application of PCM phase change nano-microcapsules under high-temperature conditions), and helps the PCM phase change nano-microcapsules maintain their shape and function in an environment with temperature fluctuations (improving durability); second, the good chemical stability of silica also means that the phase change material located in the microcapsule core can be effectively protected (preventing it from being chemically eroded and extending the service life of the PCM phase change nano-microcapsules); third, in terms of mechanical properties, the silica layer can not only significantly improve the strength of the PCM phase change nano-microcapsules, but also act as an anti-leakage layer to prevent the phase change material located in the microcapsule core from leaking, ensuring the integrity and functionality of the PCM phase change nano-microcapsules; fourth, the silica layer can also improve the compatibility of the PCM phase change nano-microcapsules with other materials, enabling them to better integrate into different substrates and application environments, and at the same time can change the surface properties of the PCM phase change nano-microcapsules (such as improving hydrophobicity or increasing surface roughness) to protect them from ultraviolet rays and other environmental factors (this is particularly important for outdoor applications, because these environmental factors may accelerate the aging and degradation of materials, and the protection of the silica layer helps to maintain the long-term performance and appearance of the PCM phase change nano-microcapsules); fifth, in terms of cleaning and maintenance, the silica-coated microcapsules are easier to clean and maintain because the silica surface is not easily adsorbed with dirt and microorganisms (this makes the clothing made of PCM phase change temperature-controlled chemical fiber easier to wash). Before use, it is also necessary to pre-treat the PCM phase change nano-microcapsules and PE (vacuum dry PE at 80 °C for 4 h, and vacuum dry the PCM phase change nano-microcapsules at 80 °C for 3 h to ensure that the moisture content of both is <50 ppm).

[0020] S2. Melting and plasticizing: Use an extrusion granulator to melt and granulate the core material and protect it with an inert atmosphere (select nitrogen to prevent high-temperature oxidation degradation, the same below) to obtain a phase change modified masterbatch. Use a twin-screw extruder (a melt pump can also be selected to replace the twin-screw extruder) to melt and extrude the phase change modified masterbatch and the skin material respectively and protect them with an inert atmosphere to obtain a molten masterbatch and a molten skin material; Among them, the core material needs to be melted to 180 °C, the phase change modified masterbatch needs to be melted to 185 °C (using this temperature design to ensure complete melting of the phase change modified masterbatch and avoid thermal degradation), and the skin material needs to be melted to 210 °C (using this temperature design to ensure sufficient melt fluidity of the skin material). The temperature control accuracy for each is ±1 °C. In addition, when preparing the molten masterbatch, the screw temperature can be adjusted between 150 and 210 °C and the chamber temperature can be adjusted between 180 and 210 °C to ensure that the melt temperature meets the requirements. When preparing the molten skin material, the screw temperature can be adjusted between 200 and 250 °C and the chamber temperature can be adjusted between 220 and 250 °C to ensure that the melt temperature meets the requirements.

[0021] S3. Dispensing and forming: A microfluidic chip (made of silicon carbide (SiC) or aluminum nitride (AlN) and with a temperature resistance > 400 °C) is used to coaxial and internal-external microfluidically dispense the molten masterbatch and the molten skin material, and then composite spinning and forming is carried out using a spinneret and a cooling system (gradient cooling device); Among them, the microfluidic chip adopts a multi-channel temperature gradient control design (controlling the core layer channel temperature at 200 °C and the sheath layer channel temperature at 220 °C) to reduce material thermal degradation on the one hand and prevent melt solidification from blocking the channels on the other hand. Secondly, the microfluidic chip controls the core layer melt pressure at 18 MPa in the core layer channel and the sheath layer melt pressure at 8 MPa in the sheath layer channel, maintaining the flow rate ratio of the core layer melt to the sheath layer melt at 1:3 (the fiber sheath layer thickness can be precisely adjusted by a gear pump), and at the same time configuring a pressure feedback system to use a piezoelectric sensor to monitor the channel pressure in real time (and then adjusting the screw speed to maintain a stable flow rate). Thirdly, the microfluidic chip adopts a coaxial double-layer channel design, with the core layer channel diameter being 200 μm and the sheath layer channel annulus width being 50 μm. In addition, the microfluidic chip also adopts an interface stability strategy. On the one hand, the sheath layer melt pressure at the entrance of the sheath layer channel is 5% higher than the core layer melt pressure at the entrance of the core layer channel through pre-pressurization to avoid backflow of the core layer melt. On the other hand, both the core layer channel and the sheath layer channel are coated with a fluorinated coating on the inner wall (contact angle > 110°) to reduce melt adhesion. The microfluidic chip also adopts a dynamic regulation technology (using electric field-assisted interface focusing), specifically by applying a DC electric field (the DC electric field can be adjusted between 1 and 5 kV / cm) to compress the fiber sheath layer thickness to less than 10 μm at the exit of the sheath layer channel using the electroviscous effect; In the spinning and forming stage, on the one hand, the aspect ratio (L / D) of the spinneret needs to be controlled at 20:1 to reduce melt elastic turbulence, and on the other hand, the draw ratio (DR) of the spinneret also needs to be controlled at 5 to adjust the fiber diameter (which can be achieved by controlling the ratio of the winding speed to the extrusion speed); among them, the spinneret needs to be seamlessly docked with the microfluidic chip and can be made of cemented carbide (such as tungsten steel); In the spinning and cooling stage (i.e., the cooling and solidification stage), a gradient cooling scheme is required (using a multi-stage air ring with a maximum temperature not exceeding 220°C and gradually decreasing to room temperature for side blowing and controlling the wind speed at 0.2 - 0.5 m / s) to avoid uneven internal stress in the fibers caused by rapid cooling, as shown in Table 1 below:

[0022]

[0023] Table 1 Spinning Cooling Gradient

[0024] In addition, during winding and collection, the winding linear speed is controlled at 15 m / min (corresponding to a fiber diameter of 25 ± 1.2 μm).

[0025] S4. Post-treatment: When the composite spinning is completed, the composite fibers are successively subjected to heat setting treatment and plasma treatment (surface functionalization); specifically, the fibers first pass through a 120°C hot roller (contact time 10 s) to eliminate residual stress and improve crystallinity, and then through plasma treatment (power 50 W, Ar gas atmosphere) to increase surface activity and facilitate subsequent coating or composite; Refer to Figure 1 , finally, the prepared PCM phase change nano-microcapsule temperature-regulating composite chemical fiber has a combined core 1 formed by the PE structure 11 and the PCM phase change nano-microcapsule structure 12 located in the inner layer, and also has a PA outer skin 2 located in the outer layer; in addition, according to multiple experimental tests, the enthalpy value of the PCM phase change nano-microcapsule temperature-regulating composite chemical fiber is 14.5 J / g (as Figure 2 shown) and the breaking strength is 2.6 cN / dtex.

[0026] The above embodiments are illustrative of the present invention and not restrictive thereof. Any scheme obtained by simply transforming the present invention belongs to the protection scope of the present invention.

Claims

1. Preparation method of PCM phase change nano microcapsule temperature-regulating composite chemical fiber, characterized in that, It includes the following steps: S1. Material preparation: Weigh PCM phase change nano microcapsules and PE to form a core material, and control the weight ratio of PCM phase change nano microcapsules to PE at 1:0.5 - 2. Weigh one or several combinations of PA, PP, and PET as the skin material, and control the weight ratio of the core material to the skin material at 1:0.5 - 1.5; S2. Melting and plasticizing: Melt - granulate the core material to obtain phase - change modified masterbatch, and melt - extrude the phase - change modified masterbatch and the skin material respectively to obtain molten masterbatch and molten skin material; S3. Dispensing and forming: Coaxially and internally - externally micro - fluidically dispense and compound - spin - form the molten masterbatch and the molten skin material.

2. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 1, characterized in that: In step S1, the particle size of the PCM phase change nano microcapsules is 500 - 700 nm and the enthalpy value is 180 - 200 J / g. The PCM phase change nano microcapsules use silica as the wall material and n - octadecane as the core material.

3. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 1, characterized in that: In step S2, use an extrusion granulator to melt - granulate the core material and protect it with an inert atmosphere. The core material needs to be melted to 150 - 200 °C. Use a twin - screw extruder to synchronously melt - extrude the phase - change modified masterbatch and the skin material and protect it with an inert atmosphere. The phase - change modified masterbatch needs to be melted to 180 - 210 °C, and the skin material needs to be melted to 200 - 220 °C.

4. The preparation method of the PCM phase change nano microcapsule temperature regulating composite chemical fiber according to claim 1, characterized in that: In step S3, use a micro - fluidic chip for micro - fluidic dispensing, control the core - layer channel temperature at 180 - 210 °C, and control the sheath - layer channel temperature at 190 - 220 °C.

5. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 4, characterized in that: In step S3, control the core - layer melt pressure at 10 - 20 MPa in the core - layer channel, control the sheath - layer melt pressure at 5 - 15 MPa in the sheath - layer channel, keep the flow rate ratio of the core - layer melt to the sheath - layer melt at 1:2 - 5, and at the same time, through pre - pressurization, make the sheath - layer melt pressure at the sheath - layer channel inlet 2 - 8% higher than the core - layer melt pressure at the core - layer channel inlet.

6. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 4, characterized in that: In step S3, the core - layer channel diameter is 180 - 220 μm and the sheath - layer channel annulus width is 40 - 60 μm. At the same time, apply a DC electric field to compress the fiber sheath - layer thickness to less than 10 μm at the sheath - layer channel outlet.

7. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 1, characterized in that: In step S3, use a spinneret to spin - spray to achieve compound spinning, and control the aspect ratio of the spinneret at 18 - 22:1 and the spinneret draw ratio at 3 - 10.

8. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 1, characterized in that: In step S3, use a multi - stage air ring with a temperature not higher than 220 °C at the highest and then gradually decreasing to room temperature to perform side - blowing during spinning, and control the wind speed at 0.2 - 0.5 m / s.

9. The preparation method of the PCM phase change nano microcapsule temperature-regulating composite chemical fiber according to claim 1, characterized in that, It also includes the following steps: Step S4. Post - treatment: When the compound spinning and forming are completed, perform heat - setting treatment and plasma treatment on the composite fiber in sequence.

10. PCM phase change nano microcapsule temperature regulating composite chemical fiber, characterized in that: Manufactured by the preparation method described in any one of claims 1 to 9, with an enthalpy value of 10 - 50 J / g and a breaking strength of 2.1 - 3.5 cN / dtex.

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