Radiation cooling nylon film, preparation method and application thereof

Abstract

This invention relates to the field of radiative cooling materials technology, and discloses a radiative cooling nylon film, its preparation method, and its applications. The invention employs a wet process to prepare the radiative cooling nylon film, specifically through a solvent-poor solvent phase inversion method. The overall preparation process is easily controlled, and the obtained radiative cooling nylon film exhibits good mechanical strength and radiative heat permeability. The radiative cooling nylon film of this invention possesses good radiative heat permeability, excellent radiative cooling capacity, and moisture permeability, resulting in good overall performance, especially in passive cooling fabrics for clothing, where it shows significant advantages.

Description

Technical Field

[0001] This invention relates to the field of radiation cooling materials technology, specifically to a radiation cooling nylon film, its preparation method, and its application. Background Technology

[0002] Unlike the emissive cooling materials commonly used in radiative cooling technology (which have high emissivity in the 8–13 μm band of the "atmospheric window"), infrared-transmitting cooling clothing materials have high transmittance in the infrared radiation band (7–14 μm) of the human body surface. This allows the body's radiant heat to be transferred to the external environment without being blocked by the clothing, thus facilitating cooling. The infrared band range of the "atmospheric window" is 8–13 μm, while the infrared band range of human body radiation is 7–14 μm. These two ranges are quite close, which prevents the spectral selectivity of the cooling material from functioning effectively. In other words, it is impossible to achieve both high emissivity and high transmittance in the mid-infrared (MIR) band through a single structural design.

[0003] Compared to polyethylene (PE), nylon (PA) has better moisture absorption and wearability, making it more suitable for clothing materials. Regarding PA cooling materials, existing literature reports the electrospinning of PA solutions into microporous membranes. For example, reference 1 [Spectral selective composite mask media for personal cooling and efficient PM 2.5 removal] developed a TiO2-doped PA6 electrospun composite fiber membrane, and reference 2 [Infrared-Radiation-Enhanced Nanofiber Membrane for SkyRadiative Cooling of the Human Body] described a SiO2-doped PA6 electrospun composite fiber membrane. Both spun PA composite fiber membranes exhibit good radiative cooling capabilities. However, the performance of electrospun membranes is greatly affected by spinning process parameters and is difficult to control; furthermore, due to the inherent characteristics of electrospinning technology, electrospun nanofiber materials generally suffer from insufficient mechanical strength.

[0004] Phase inversion is currently the main method for preparing polymer separation and filtration membranes, with solution phase inversion being the most widely used. Its preparation process is simple, offers greater process variability, and allows for better adjustment of the membrane's structure and performance according to its application. Furthermore, there are currently no research reports on the preparation of PA microporous membranes using the solvent-poor solvent phase inversion method (a wet process in the textile and apparel industry) for application in "mid-infrared transmission-solar spectrum reflection" cooling clothing materials. Summary of the Invention

[0005] The purpose of this invention is to address the limitation of existing radiative cooling materials in terms of performance, thereby providing a radiative cooling nylon film. This radiative cooling nylon film uses nylon as the substrate and is filled with heat-reflective inorganic particles, exhibiting good porosity for heat radiation transmission and possessing excellent radiative cooling and moisture permeability.

[0006] The present invention also aims to address the problems of difficult process control and insufficient mechanical strength of existing electrospinning methods for preparing nylon film materials, by providing a method for preparing a radiation-cooling nylon film. This method uses nylon as the substrate and heat-reflective inorganic particles as heat-reflective fillers. A solvent-poor solvent phase inversion process is used to prepare a nylon microporous membrane, resulting in a nylon membrane with good heat radiation permeability porosity, thus obtaining a radiation-cooling nylon film.

[0007] Another objective of this invention is to provide the application of the aforementioned radiative cooling nylon film, specifically its application in the preparation of clothing materials.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for preparing a radiation-cooling nylon film includes the following steps:

[0010] The nylon substrate is dissolved, and additives and heat-reflective inorganic particles are added to the nylon substrate solution to form a mixed solution. The mixed solution is degassed, coated, and impregnated and solidified in a good solvent-poor solvent to obtain the radiation cooling nylon film.

[0011] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the nylon substrate is nylon powder, and formic acid solution or formic acid-methanol mixture is used as solvent to dissolve the nylon substrate. The mass concentration of the formic acid solution is 85-98%, preferably 85%, and the mass ratio of formic acid to methanol in the formic acid-methanol mixture is 10-20:1-3.

[0012] As a further preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the nylon substrate and the solvent are dissolved and mixed by stirring at a speed of 1000-1500 rpm for 30-60 minutes at room temperature until dissolved.

[0013] In a further preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of the nylon substrate to the solvent is 3-7:14-40.

[0014] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the additives include one or more of a softener, a defoamer, and an anti-tear agent.

[0015] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of the nylon substrate to the additive is 15-35:1-5.

[0016] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the heat-reflective inorganic particles include one or more of SiO2, TiO2, ZrO2, Y2O3, h-BN, SiC, and BaSO4.

[0017] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the particle size of the heat-reflective inorganic particles is 0.1-10 μm.

[0018] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of the nylon substrate to the heat-reflective inorganic particles is 3-7:1-8.

[0019] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solution of the additive and the nylon substrate is mixed by stirring at a speed of 600-1200 rpm for 10-30 minutes at room temperature until it is uniformly dissolved.

[0020] As a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solution of the heat-reflective inorganic particles and the nylon substrate is mixed by stirring at a speed of 1000-1500 rpm for 10-30 minutes at room temperature until it is uniformly dissolved.

[0021] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the coating thickness is 0.1-1.5 mm.

[0022] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the good solvent-poor solvent is a formic acid-water solution with a mass concentration of 10-30%.

[0023] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solidification time is 3-5 minutes.

[0024] In a preferred embodiment of the method for preparing the radiative cooling nylon membrane of the present invention, the porosity of the obtained radiative cooling nylon membrane is 0.4-0.8.

[0025] A radiative cooling nylon film is prepared by any of the above-described methods for preparing radiative cooling nylon films.

[0026] The aforementioned applications of the radiative cooling nylon film include its use in the preparation of clothing materials.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The present invention discloses a method for preparing a radiation-cooling nylon membrane. Nylon is used as the substrate, and heat-reflective inorganic particles are used as heat-reflective fillers. A nylon microporous membrane is prepared by a solvent-poor solvent phase conversion process, so that the prepared nylon membrane has good heat radiation transmittance porosity, and a radiation-cooling nylon membrane is obtained. The overall preparation process is easy to control, and the obtained nylon membrane has good mechanical strength and radiation heat transmittance.

[0029] The radiation-cooling nylon membrane of the present invention is prepared by a wet film-forming process and filled with heat-reflective inorganic particles. The reflectivity of the membrane material in the near-light and near-infrared light bands can be adjusted. At the same time, the pores formed in the membrane combined with the thermal radiation properties of the nylon substrate itself give the membrane material good permeability. Specifically, it is a radiation-cooling nylon membrane with mid-infrared transmission and solar spectrum reflection. This radiation-cooling nylon membrane has excellent radiation cooling capacity and moisture permeability.

[0030] The radiative cooling nylon film of the present invention has good radiative heat permeability, excellent radiative cooling capacity and moisture permeability, and good overall performance, especially in the application of passive cooling fabrics for clothing. Attached Figure Description

[0031] Figure 1 SEM image of the PA wet-process composite film doped with 30 wt% TiO2 particles (0.5 μm in diameter) prepared in Example 1.

[0032] Figure 2 The UV-Vis-NIR spectrum of the PA wet-process composite film doped with 30 wt% TiO2 particles (0.5 μm in diameter) prepared in Example 1 is shown.

[0033] Figure 3 SEM image of the PA wet-process composite film doped with 30 wt% ZrO2 particles (0.1 μm in diameter) prepared in Example 2.

[0034] Figure 4 The UV-Vis-NIR spectrum of the PA wet-process composite film doped with 30 wt% ZrO2 particles (0.1 μm in diameter) prepared in Example 2 is shown.

[0035] Figure 5 SEM image of the PA wet-process composite film doped with 30 wt% TiO2 particles (0.1 μm in diameter) prepared in Example 3.

[0036] Figure 6 The UV-Vis-NIR spectrum of the PA wet-process composite film doped with 30 wt% TiO2 particles (0.1 μm in diameter) prepared in Example 3 is shown.

[0037] Figure 7 SEM image of the pure PA wet-process composite membrane prepared for Comparative Example 1.

[0038] Figure 8 The UV-Vis-NIR spectrum of the pure PA wet-process membrane prepared for Comparative Example 1 is shown. Detailed Implementation

[0039] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0040] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0041] It should be understood that the singular forms used in this invention, such as "a," include plural references unless otherwise specified. Furthermore, the terms "comprising," "containing," and "having" are open-ended rather than closed-ended, meaning they include the contents specified in this invention but do not exclude other aspects. In other words, the terms also include "consistently made of" or "composed of."

[0042] Furthermore, "and combinations thereof" in the specification refers to any combination of all the listed items. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0043] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0044] Unless otherwise specified, this invention employs standard nomenclature and standard laboratory procedures and techniques of analytical chemistry, organic synthetic chemistry and optics.

[0045] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0046] The method for preparing the radiation-cooling nylon film of the present invention, which prepares a porous radiation-cooling nylon film by solvent-poor solvent phase conversion method, specifically includes the following steps:

[0047] The nylon substrate is dissolved, and additives and heat-reflective inorganic particles are added to the nylon substrate solution to form a mixed solution. The mixed solution is degassed, coated, and impregnated and solidified in a good solvent-poor solvent to obtain the radiation cooling nylon film.

[0048] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the nylon substrate is nylon powder, which may be selected from, but is not limited to, one or more of PA6 and PA66.

[0049] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the nylon substrate is dissolved in formic acid solution or formic acid-methanol mixture.

[0050] More preferably, the formic acid solution has a mass concentration of 85-98%.

[0051] More preferably, the mass ratio of formic acid to methanol in the formic acid-methanol mixed solution is 10-20:1-3.

[0052] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the nylon substrate and the solvent are dissolved and mixed by stirring at a speed of 1000-1500 rpm for 30-60 minutes at room temperature until dissolved.

[0053] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of nylon substrate to solvent is 3-7:14-40, specifically 3-5:17-40, 3-4:17-40, 5-7:17-40, 3-7:20-40, 3-7:25-40, 3-7:30-40, 3-7:35-40, 3-7:17-30, 3-7:17-25, 3-7:17-20, 3-5:25-35, 3-5:25-30, 3-4:25-30, or 1:4 or 3:7.

[0054] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the additives include one or more of a softener, a defoamer, and an anti-tear agent.

[0055] More preferably, the softener includes cationic softeners or silicone softeners.

[0056] More preferably, the defoaming agent includes an organosilicon defoaming agent.

[0057] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of nylon substrate to additives is 15-35:1-5, specifically 20-35:1-5, 25-35:1-5, 30-35:1-5, 15-30:1-5, 15-25:1-5, 15-20:1-5, 15-25:1-3, 15-20:1-3, 15-25:3-5, 15-20:3-5, 20-25:1-3, 20:1, or 30:1.

[0058] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the heat-reflective inorganic particles include one or more of SiO2, TiO2, ZrO2, Y2O3, h-BN, SiC and BaSO4, and more preferably one or more of TiO2 and ZrO2.

[0059] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the particle size of the heat-reflective inorganic particles is 0.1-10 μm, specifically 0.1-8 μm, 0.1-6 μm, 0.1-5 μm, 0.1-3 μm, 0.1-1 μm, 0.1-0.8 μm, 0.5-6 μm, 0.5-5 μm, 0.5-3 μm, 1-5 μm, 1-3 μm, 2-6 μm, 2-5 μm, 0.1 μm, 0.2 μm, 0.8 μm, or 1 μm.

[0060] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the mass ratio of the nylon substrate to the heat-reflective inorganic particles is 3-7:1-8, 3-6:1-8, 3-5:1-8, 3-4:1-8, 3-7:1-5, 3-7:2-8, 3-7:3-8, 3-7:5-8, 3-7:6-8, 3-5:2-5, 3-4:2-5, 3-5:3-6, 3-5:2-3, 1:1, or 2:3.

[0061] As a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solution of the additive and the nylon substrate is mixed by stirring at a speed of 600-1200 rpm for 10-30 minutes at room temperature until it is uniformly dissolved.

[0062] As a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solution of heat-reflective inorganic particles and nylon substrate is mixed by stirring at a speed of 1000-1500 rpm for 10-30 minutes at room temperature until it is uniformly dissolved.

[0063] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the coating thickness is 0.1-1.5 mm, and can be selected as 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 1.0 mm, 1.3 mm, or 1.5 mm.

[0064] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the good solvent-poor solvent is a formic acid-water solution with a mass concentration of 10-30%. Specifically, the good solvent in the good solvent-poor solvent mixture is formic acid, the poor solvent is water, and the mass concentration of formic acid is 10-30%.

[0065] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the solidification time is 3-5 minutes.

[0066] In a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the coating can be applied to a glass plate by scraping.

[0067] In a preferred embodiment of the method for preparing the radiative cooling nylon membrane of the present invention, the porosity of the obtained radiative cooling nylon membrane is 0.4-0.8.

[0068] As a preferred embodiment of the method for preparing the radiative cooling nylon film of the present invention, the method for preparing the radiative cooling nylon film of the present invention may further include the following steps: after the solidified film material is removed from the coated substrate, it undergoes at least one water-squeezing process, is then washed with water, and finally placed in an environment of 20-25°C to air dry naturally.

[0069] The radiative cooling nylon film of the present invention is prepared by any of the above-mentioned methods for preparing radiative cooling nylon films.

[0070] The aforementioned applications of radiative cooling nylon films include their use in the preparation of clothing materials.

[0071] Example 1

[0072] The specific preparation steps of the radiation cooling nylon membrane in this embodiment are as follows:

[0073] PA wet process material preparation

[0074] (1) By weight, add 20 parts of PA6 powder to 80 parts of formic acid solution with a concentration of 85wt%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0075] (2) Add 1 part of cationic softener to the mixed solution formed in (1), stir at 1000 rpm for 30 minutes at room temperature, and let stand to remove bubbles before use;

[0076] (3) Add 30 portions of TiO2 inorganic particles with a particle size of 0.5 μm to the mixed solution filtered in process (2), stir at 1400 rpm for 30 minutes at room temperature, and then let it stand to remove bubbles before use.

[0077] Preparation of microporous membranes

[0078] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.1 mm; then it is immersed in a 20% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by water washing, and finally placed in an environment of 25℃ to air dry naturally.

[0079] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.12 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.86 by FTIR test. The porosity was 0.74 by mercury porosimetry test.

[0080] The SEM observation results of the prepared radiation-cooling nylon film are as follows: Figure 1 As shown. The UV-Vis-NIR (ultraviolet-visible-near-infrared) spectroscopy results (Shimadzu UV-3600plus spectrometer) of the prepared radiation-cooling nylon film are as follows: Figure 2 As shown, by Figure 2 It can be seen that the relative reflectance of the composite film is 0.98 in the 380-1000nm solar spectrum band.

[0081] Example 2

[0082] The specific preparation steps of the radiation cooling nylon membrane in this embodiment are as follows:

[0083] PA wet process material preparation

[0084] (1) By mass, add 30 parts of PA6 powder to 70 parts of formic acid solution with a concentration of 85wt%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0085] (2) To add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 30 minutes at room temperature, and let stand to remove bubbles before use;

[0086] (3) Add 30 parts of ZrO2 inorganic particles with a particle size of 0.1μm to the mixed solution filtered in process (2), stir at 1400 rpm for 30 minutes at room temperature, and then let it stand to remove bubbles before use.

[0087] Preparation of microporous membranes

[0088] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.25 mm; then it is immersed in a 15% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by water washing, and finally placed in an environment of 25°C to air dry naturally.

[0089] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.26 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.83 by FTIR test. The porosity was 0.46 by mercury porosimetry test.

[0090] The SEM observation results of the prepared radiation-cooling nylon film are as follows: Figure 3 As shown. The UV-Vis-NIR spectroscopy test results (Shimadzu UV-3600plus spectrometer) of the prepared radiation-cooling nylon film are as follows. Figure 4 As shown, by Figure 4 It can be seen that the relative reflectance of the composite film is 0.99 in the 380-1000nm solar spectrum band.

[0091] Example 3

[0092] The specific preparation steps of the radiation cooling nylon membrane in this embodiment are as follows:

[0093] PA wet process material preparation

[0094] (1) By mass, add 30 parts of PA6 powder to 70 parts of formic acid solution with a concentration of 85%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0095] (2) To add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 30 minutes at room temperature, and let stand to remove bubbles before use;

[0096] (3) Add 30 portions of TiO2 inorganic particles with a particle size of 0.1 μm to the mixed solution filtered in process (2), stir at 1400 rpm for 30 minutes at room temperature, and then let it stand to remove bubbles before use.

[0097] Preparation of microporous membranes

[0098] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.25 mm; then it is immersed in a 15% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by water washing, and finally placed in an environment of 25°C to air dry naturally.

[0099] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.27 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.82 by FTIR test. The porosity was 0.51 by mercury porosimetry test.

[0100] The SEM observation results of the prepared radiation-cooling nylon film are as follows: Figure 5 As shown. The UV-Vis-NIR spectroscopy test results (Shimadzu UV-3600plus spectrometer) of the prepared radiation-cooling nylon film are as follows. Figure 6 As shown, by Figure 6 It can be seen that the relative reflectance of the composite film is 0.98 in the 380-1000nm solar spectrum band.

[0101] Example 4

[0102] The cooling nylon film and its preparation method in this comparative example are detailed in the following steps:

[0103] PA wet process material preparation

[0104] (1) By mass, add 25 parts of PA 6 powder to 75 parts of formic acid solution with a concentration of 85%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0105] (2) To add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 30 minutes at room temperature, and let stand to remove bubbles before use;

[0106] (3) Add 5 portions of TiO2 inorganic particles with a particle size of 0.1 μm to the mixed solution filtered in process (2), stir at 1400 rpm for 30 minutes at room temperature, and then let stand to remove bubbles for later use.

[0107] Preparation of microporous membranes

[0108] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.20 mm; then it is immersed in a 15% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by washing, and finally placed in an environment of 25°C to air dry naturally.

[0109] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.10 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.84 by FTIR testing.

[0110] Comparative Example 1

[0111] The specific preparation steps of the cooling nylon membrane in this comparative example are as follows:

[0112] PA wet process material preparation

[0113] (1) By mass, add 30 parts of PA 6 powder to 70 parts of formic acid solution with a concentration of 85%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, let stand to remove bubbles and set aside for use;

[0114] (2) Add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 30 minutes at room temperature, and let stand to remove bubbles before use.

[0115] Preparation of microporous membranes

[0116] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.25 mm; then it is immersed in a 15% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by water washing, and finally placed in an environment of 25°C to air dry naturally.

[0117] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.26 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.83 by FTIR test. The porosity was 0.44 by mercury porosimetry test.

[0118] The SEM observation results of the prepared radiation-cooling nylon film are as follows: Figure 7 As shown. The UV-Vis-NIR spectroscopy test results (Shimadzu UV-3600plus spectrometer) of the prepared radiation-cooling nylon film are as follows. Figure 8 As shown, by Figure 8 It can be seen that the relative reflectance of the composite film is 0.96 in the 380-1000nm solar spectrum band.

[0119] Comparative Example 2

[0120] The specific preparation steps of the radiation-cooling nylon film in this comparative example are as follows:

[0121] PA wet process material preparation

[0122] (1) By mass, add 35 parts of PA 6 powder to 65 parts of formic acid solution with a concentration of 85wt%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0123] (2) Add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 20 minutes at room temperature, and let stand to remove bubbles before use.

[0124] Preparation of microporous membranes

[0125] The degassed PA wet process material mixture solution is scraped onto a glass plate with a coating thickness of 0.20 mm; then it is immersed in a 15% formic acid-water solution for solidification for 5 minutes; the film is peeled off the glass plate and then undergoes a water-squeezing process, followed by washing, and finally placed in an environment of 25°C to air dry naturally.

[0126] The prepared radiation-cooling nylon film was tested. The film thickness was measured to be 0.33 mm by a thickness gauge. The average transmittance of the PA composite film in the 7-14 μm infrared band was 0.79 by FTIR testing.

[0127] Comparative Example 3

[0128] The specific preparation steps of the radiation-cooling nylon film in this comparative example are as follows:

[0129] PA wet process material preparation

[0130] (1) By mass, add 40 parts of PA 6 powder to 80 parts of formic acid solution with a concentration of 85wt%, stir at 1400 rpm for 30 minutes at room temperature until dissolved, and let stand to remove bubbles before use;

[0131] (2) Add 1 part of cationic softener to the mixed solution formed in process (1), stir at 1000 rpm for 20 minutes at room temperature, and let stand to remove bubbles before use.

[0132] (3) Add 30 portions of TiO2 inorganic particles with a particle size of 0.1 μm to the mixed solution filtered in process (2), stir at 1400 rpm for 30 minutes at room temperature, and then let it stand to remove bubbles before use.

[0133] Preparation of microporous membranes

[0134] When the degassed PA wet process mixture is scraped onto a glass plate, the mixture has poor fluidity and cannot form a film.

[0135] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, this specification does not describe all possible combinations of the technical features in the above embodiments. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Furthermore, the above embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent.

[0136] It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for producing a radiative cooling nylon film, characterized by, The process includes the following steps: dissolving a nylon substrate, adding additives and heat-reflective inorganic particles to the nylon substrate solution, and combining them into a mixed solution; degassing and coating the mixed solution, and impregnating and solidifying it in a good solvent-poor solvent mixture to obtain the radiation-cooling nylon film. The nylon substrate is nylon powder, and the nylon substrate is dissolved in formic acid solution or formic acid-methanol mixture as solvent. The mass concentration of the formic acid solution is 85-98%, and the mass ratio of formic acid to methanol in the formic acid-methanol mixture is 10-20:1-3. The good solvent-poor solvent is a formic acid-water solution with a mass concentration of 10-30%; the solidification time is 3-5 minutes.

2. The method of claim 1, wherein the radiation-cooled nylon film is prepared by the steps of: The nylon substrate and the solvent are dissolved and mixed by stirring at 1000-1500 rpm for 30-60 minutes at room temperature until dissolved.

3. The method for preparing the radiative cooling nylon film according to claim 1, characterized in that, The mass ratio of the nylon substrate to the solvent is 3-7:14-40.

4. The method for preparing the radiation-cooling nylon film according to claim 1, characterized in that, The additives include one or more of softeners, defoamers, and tear-resistant agents; and / or, the mass ratio of the nylon substrate to the additives is 15-35:1-5.

5. The method for preparing the radiative cooling nylon film according to claim 1, characterized in that, The heat-reflective inorganic particles include one or more of SiO2, TiO2, ZrO2, Y2O3, h-BN, SiC, and BaSO4; and / or, the particle size of the heat-reflective inorganic particles is 0.1-10 μm.

6. The method for preparing the radiation-cooling nylon film according to claim 1, characterized in that, The mass ratio of the nylon substrate to the heat-reflective inorganic particles is 3-7:1-8.

7. The method for preparing the radiative cooling nylon film according to claim 1, characterized in that, The mixing of the additive with the nylon substrate solution is as follows: stirring at 600-1200 rpm for 10-30 minutes at room temperature until uniformly dissolved; and / or, the mixing of the heat-reflective inorganic particles with the nylon substrate solution is as follows: stirring at 1000-1500 rpm for 10-30 minutes at room temperature until uniformly dissolved.

8. The method for preparing the radiative cooling nylon film according to claim 1, characterized in that, The coating thickness is 0.1-1.5 mm.

9. The method for preparing the radiative cooling nylon film according to claim 1, characterized in that, The porosity of the obtained radiation-cooling nylon membrane is 0.4-0.

8.

10. The radiation-cooling nylon film prepared by the preparation method of any one of claims 1-9.

11. The application of the radiative cooling nylon film of claim 10, characterized in that, This includes applications in the preparation of clothing materials.

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