Radiation refrigeration fiber membrane with wetting gradient as well as preparation method and application of radiation refrigeration fiber membrane

Abstract

The invention discloses a radiation refrigeration fiber membrane with wetting gradient and a preparation method and application thereof, and belongs to the technical field of polymeric membranes. The radiation refrigeration fiber comprises a hydrophobic fiber membrane and a hydrophilic fiber membrane, the preparation raw materials of the hydrophobic fiber membrane comprise polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer; the hydrophilic fiber membrane is prepared from the following raw materials: polyamide and dodecyl trimethyl ammonium bromide. The preparation method comprises the following steps: S1, mixing polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer to obtain a spinning solution A, and performing electrostatic spinning to obtain a hydrophobic fiber membrane; s2, the hydrophobic fiber membrane serves as a spinning base material, polyamide and dodecyl trimethyl ammonium bromide are mixed into a spinning solution B, a hydrophilic fiber membrane is prepared through electrostatic spinning, and the radiation refrigeration fiber membrane is obtained. The oriented moisture-absorbing and quick-drying radiation refrigeration fabric has an oriented structure, also has excellent moisture-absorbing and quick-drying properties and a radiation refrigeration function, and has a wide application prospect in the fields of clothes, buildings, agriculture and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer membranes, and in particular to a radiation refrigeration fiber membrane with a wetting gradient, a preparation method thereof and applications thereof. Background Art

[0002] As global temperatures continue to rise, people engaged in sports, military activities, and special occupations such as construction, firefighting, and medical care are easily exposed to extreme high temperature environments, facing severe challenges such as lack of thermal comfort and excessive sweating. This discomfort may not only weaken their work efficiency, but also cause a series of health problems. In order to effectively deal with this problem, ventilation and air conditioning systems commonly used for active cooling in indoor spaces have low energy efficiency and are difficult to adapt to the application needs of outdoor environments. Although solutions for personal active cooling, such as liquid cooling, air cooling, semiconductor cooling, and electric heat cooling, have relatively low energy consumption, they are large and bulky, making them unsuitable for ordinary people to wear and use in daily life. In contrast, passive radiative cooling technology has brought new hope to the field of personal cooling. This technology releases energy in the form of infrared (IR) radiation and cleverly uses the method of reflecting sunlight to achieve the effect of cooling without external power supply, showing great application potential. However, the current radiative cooling fabrics generally have insufficient moisture management capabilities. This is particularly obvious when the human body sweats, which not only causes extreme discomfort to the skin, but also seriously affects the cooling efficiency. More importantly, since the specific heat capacity and density of water are greater than those of air, excess residual sweat on the skin will accumulate heat, which will have a negative effect on the thermal comfort and overall cooling performance of the radiant cooling fabric.

[0003] In recent years, electrospinning technology has become a cutting-edge technology for the preparation of nanofibers due to its convenient operation and wide source of raw materials. Electrospinning nanofibers have the advantages of small diameter, high porosity, and large specific surface area. Therefore, the use of electrospinning technology is the best choice for the development of radiant cooling fabrics with excellent moisture absorption and perspiration wicking capabilities, in order to improve the moisture and heat management capabilities while further improving the radiant cooling effect.

[0004] Therefore, it is necessary to provide a radiant fiber film with excellent moisture absorption and perspiration removal ability to solve the above problems. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a radiative cooling fiber membrane with a wetting gradient, which has excellent moisture absorption and perspiration removal performance and radiative cooling effect.

[0006] The present invention also provides a method for preparing the radiation refrigeration fiber membrane.

[0007] The present invention also provides application of the radiation refrigeration fiber membrane.

[0008] The first aspect of the present invention provides the above-mentioned radiation cooling fiber membrane, wherein the radiation cooling fiber comprises a hydrophobic fiber membrane and a hydrophilic fiber membrane;

[0009] The raw materials for preparing the hydrophobic fiber membrane include polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer; the raw materials for preparing the hydrophilic fiber membrane include polyamide and dodecyltrimethylammonium bromide.

[0010] The radiation cooling fiber membrane according to the first aspect of the present invention has at least the following beneficial effects:

[0011] The radiative cooling fiber membrane of the present invention has a double-layer structure of a hydrophobic fiber membrane and a hydrophilic fiber membrane, and the hydrophobic fiber membrane not only has excellent hydrophobicity, but also has high reflectivity and high infrared emissivity. Due to the addition of DTAB, the hydrophilicity of the PA6 fiber membrane is improved, and the PA6 / DTAB hydrophilic fiber membrane has an oriented structure. The fiber membrane of the present invention has excellent moisture absorption and quick drying properties and radiative cooling functions, and has broad application prospects in the fields of clothing, construction, agriculture, etc.

[0012] The raw materials for preparing the hydrophobic fiber membrane of the present invention include polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and fluorine-containing polymers. Due to the introduction of fluorine atoms, its surface energy is reduced, thereby exhibiting excellent hydrophobic properties and being able to effectively prevent moisture penetration and accumulation; at the same time, the CF bond improves the thermal emission characteristics in the atmospheric window band (8-13μm), enabling it to effectively emit heat into outer space in the form of infrared radiation, thereby enhancing the radiation cooling effect.

[0013] The raw materials for preparing the hydrophilic fiber membrane of the present invention include polyamide (PA6) and dodecyltrimethylammonium bromide (DTAB). The PA6 material is mostly composed of CC and CH molecular bonds, highly scatters visible light, is opaque in the visible light range, has low absorptivity in the infrared spectrum range, and has a narrow absorption peak in the human body radiation band range. Therefore, it has high infrared transmittance in the mid-infrared range and can effectively transmit human infrared radiation to achieve a cooling effect. The addition of DTAB improves the conductivity of the solution, the polymer jet is subjected to a stronger electric field stretching effect, the fiber diameter becomes smaller, the specific surface area increases, and its surface energy is increased. The fiber surface has more opportunities to contact with water molecules, thereby enhancing the adsorption capacity of water molecules and improving the hydrophilic effect.

[0014] According to some embodiments of the present invention, the average pore size of the hydrophobic fiber membrane is 1.0 μm to 4.5 μm.

[0015] Preferably, the average pore size of the hydrophobic fiber membrane is 3.0 μm to 4.2 μm.

[0016] According to some embodiments of the present invention, the average pore size of the hydrophilic fiber membrane is 0.15 μm to 0.75 μm.

[0017] Preferably, the average pore size of the hydrophilic fiber membrane is 0.2 μm to 0.7 μm.

[0018] According to some embodiments of the present invention, the average pore size of the hydrophobic fiber membrane is greater than the average pore size of the hydrophilic fiber membrane.

[0019] A pore size gradient is constructed in the fiber membrane of the present invention, so that the liquid in the material can spontaneously move from the large pore side to the small pore side. Through the specific pore size gradient, rapid conduction of water in a specific direction can be achieved. Specifically, the inner layer (usually the hydrophobic layer) of the fiber membrane is designed to have a relatively large pore size, while the outer layer (hydrophilic layer) has a smaller pore size.

[0020] According to some embodiments of the present invention, the fluorine-containing polymer includes at least one of perfluorooctyltriethoxysilane (FAS), perfluorodecyltriethoxysilane (FTES), trifluoropropyltrimethoxysilane (TFPTMS), heptadecafluorodecyltrimethoxysilane (HDTDS), dodecafluoroheptylpropyltrimethoxysilane (DFHPTMS), hexafluorobutylpropyltrimethoxysilane (HFBPTMS), fluorinated polyurethane (FPU), fluorinated polyimide (FPI), fluorinated polyacrylate, fluorinated ethylene-propylene copolymer (FEP), and perfluoroalkoxy resin (PFA).

[0021] Preferably, the fluorine-containing polymer includes at least one of perfluorooctyltriethoxysilane (FAS), perfluorodecyltriethoxysilane (FTES), fluorinated polyimide (FPI) and perfluoroalkoxy resin (PFA).

[0022] According to some embodiments of the present invention, the hydrophobic fiber membrane has a thickness of 200 μm to 240 μm.

[0023] Preferably, the thickness of the hydrophobic fiber membrane is 220 μm to 240 μm.

[0024] According to some embodiments of the present invention, the hydrophilic fiber membrane has a thickness of 70 μm to 100 μm.

[0025] A second aspect of the present invention provides a method for preparing the above-mentioned radiative cooling fiber membrane, the preparation method comprising the following steps:

[0026] S1, mixing polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer into a spinning solution A, and electrospinning to obtain a hydrophobic fiber membrane;

[0027] S2. Using the hydrophobic fiber membrane as a spinning substrate, mixing polyamide and dodecyltrimethylammonium bromide into a spinning solution B, and electrospinning to obtain a hydrophilic fiber membrane, thereby obtaining the radiation refrigeration fiber membrane.

[0028] According to some embodiments of the present invention, in step S1, the concentration of polyvinylidene fluoride-hexafluoropropylene in the spinning solution A is 12 wt% to 18 wt%.

[0029] Preferably, in step S1, the concentration of polyvinylidene fluoride-hexafluoropropylene in the spinning solution A is 14 wt% to 16 wt%.

[0030] According to some embodiments of the present invention, in step S1, the concentration of the fluorine-containing polymer in the spinning solution A is 3 wt% to 15 wt%.

[0031] Preferably, in step S1, the concentration of the fluorine-containing polymer in the spinning solution A is 4 wt% to 12 wt%.

[0032] According to some embodiments of the present invention, in step S2, the concentration of polyamide in the spinning solution B is 12 wt% to 16 wt%.

[0033] Preferably, in step S2, the concentration of polyamide in the spinning solution B is 14 wt% to 15 wt%.

[0034] According to some embodiments of the present invention, in step S2, the concentration of dodecyltrimethylammonium bromide in the spinning solution B is 8 wt % to 14 wt %.

[0035] Preferably, in step S2, the concentration of dodecyltrimethylammonium bromide in the spinning solution B is 10 wt% to 13 wt%.

[0036] If the concentration of the hydrophilic fiber membrane is too high, the fiber will be overstretched, which may weaken its performance. If the concentration is too low, the ideal hydrophilicity cannot be obtained, and thus the excellent moisture absorption and perspiration effect cannot be achieved.

[0037] According to some embodiments of the present invention, in step S1, the electrospinning voltage is 25 kV to 30 kV.

[0038] According to some embodiments of the present invention, in step S1, the electrospinning receiving distance is 23 cm to 25 cm.

[0039] According to some embodiments of the present invention, in step S1, the electrospinning perfusion speed is 1 to 3 mL / h.

[0040] According to some embodiments of the present invention, in step S1, the electrospinning temperature is 25°C to 27°C.

[0041] According to some embodiments of the present invention, in step S1, the relative humidity of the electrospinning is 80% to 90%.

[0042] According to some embodiments of the present invention, in step S2, the electrospinning voltage is 25 kV to 30 kV.

[0043] According to some embodiments of the present invention, in step S2, the electrospinning receiving distance is 20 cm to 23 cm.

[0044] According to some embodiments of the present invention, in step S2, the electrospinning perfusion speed is 1 to 2 mL / h.

[0045] According to some embodiments of the present invention, in step S2, the electrospinning temperature is 25°C to 27°C.

[0046] According to some embodiments of the present invention, in step S2, the relative humidity of the electrospinning is 40% to 45%.

[0047] According to a third aspect of the present invention, there is provided application of the above-mentioned radiation cooling fiber membrane in the fields of personal protection, professional equipment, sportswear and medical supplies.

[0048] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0050] Figure 1 This is an electron microscope image of the hydrophilic fiber membrane in Example 1 of the present invention;

[0051] Figure 2 This is an electron microscope image of the hydrophobic fiber membrane in Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The embodiments of the present invention are described in detail below, and the same or similar reference numerals throughout the embodiments represent the same or similar elements or elements with the same or similar functions. The embodiments described below are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0053] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0054] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0055] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0057] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0058] Some of the raw materials of the present invention are as follows:

[0059] PVDF-HFP: purchased from Shanghai Aichun Biotechnology Co., Ltd.

[0060] PA6: purchased from Jiangmen Tongfeng Chemical Glass Equipment Co., Ltd.

[0061] DTAB: purchased from Sinopharm Chemical Reagent Co., Ltd.

[0062] FAS: purchased from Zhongshan Yuanda New Materials Co., Ltd.

[0063] FTES: purchased from Guangzhou Chuanliu Chemical Reagent Co., Ltd.

[0064] TFPTMS: purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0065] HDTDS: purchased from Hubei Xinkang Pharmaceutical Chemical Co., Ltd.

[0066] DFHPTMS: purchased from Shanghai Koraman Reagent Co., Ltd.

[0067] HFBPTMS: purchased from Shanghai Baoman Biotechnology Co., Ltd.

[0068] FPU: purchased from Yangzhou Haizhineng Anticorrosion Materials Co., Ltd.

[0069] FPI: purchased from DuPont.

[0070] Fluorinated polyacrylate: purchased from Guangzhou Yifeng Chemical Technology Co., Ltd.

[0071] FEP: purchased from Dongguan Prius Plastic Raw Materials.

[0072] PFA: purchased from Shanghai Puzhen Biotechnology Co., Ltd.

[0073] SDS: Sodium dodecyl sulfate, purchased from Suzhou Chenxiang Chemical Co., Ltd.

[0074] PU: polyurethane, purchased from Jiangmen Tongfeng Chemical Glass Equipment Co., Ltd.

[0075] Example 1

[0076] This embodiment provides a radiative cooling fiber membrane with a wetting gradient, specifically: the fluorine-containing polymer is FAS; the thickness of the hydrophobic fiber membrane is 220 μm, the thickness of the hydrophilic fiber membrane is 70 μm, the pore size of the hydrophobic fiber membrane is 3.8 μm, and the pore size of the hydrophilic fiber membrane is 0.2 μm.

[0077] This embodiment also provides a method for preparing the above-mentioned radiation cooling fiber membrane, comprising the following steps:

[0078] 1) Using glossy paper as a receiving substrate, 12 wt% PVDF-HFP and 12 wt% FAS were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 1 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0079] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 13wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 26kV, receiving distance 15cm, infusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0080] Example 2

[0081] This embodiment provides a radiative cooling fiber membrane with a wetting gradient, specifically: the fluorine-containing polymer is FTES; the hydrophobic membrane thickness is 230 μm, the hydrophilic fiber membrane thickness is 76 μm, the hydrophobic fiber membrane pore size is 3.5 μm, and the hydrophilic fiber membrane pore size is 0.2 μm.

[0082] This embodiment also provides a method for preparing the above-mentioned radiation cooling fiber membrane, comprising the following steps:

[0083] 1) Using glossy paper as a receiving substrate, 14 wt% PVDF-HFP and 4 wt% FTES were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 27 kV, receiving distance 25 cm, perfusion speed 2 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0084] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 10wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 18cm, infusion rate 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0085] Example 3

[0086] This embodiment provides a radiative cooling fiber membrane with a wetting gradient, specifically: the fluorine-containing polymer is FPI; the hydrophobic membrane thickness is 240 μm, the hydrophilic fiber membrane thickness is 80 μm, the hydrophobic fiber membrane pore size is 4.0 μm, and the hydrophilic fiber membrane pore size is 0.7 μm.

[0087] This embodiment also provides a method for preparing the above-mentioned radiation cooling fiber membrane, comprising the following steps:

[0088] 1) Using glossy paper as a receiving substrate, 18 wt% PVDF-HFP and 7 wt% FPI were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 30 kV, receiving distance 25 cm, perfusion speed 2 mL / h, temperature 25° C., relative humidity 85%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0089] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 8wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, perfusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0090] Example 4

[0091] This embodiment provides a radiative cooling fiber membrane with a wetting gradient, specifically: the fluorine-containing polymer is PFA; the hydrophobic membrane thickness is 230 μm, the hydrophilic fiber membrane thickness is 85 μm, the hydrophobic fiber membrane pore size is 4.2 μm, and the hydrophilic fiber membrane pore size is 0.6 μm.

[0092] This embodiment also provides a method for preparing the above-mentioned radiation cooling fiber membrane, comprising the following steps:

[0093] 1) Using glossy paper as a receiving substrate, 14 wt% PVDF-HFP and 6 wt% PFA were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 1 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0094] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 12wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, perfusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0095] Comparative Example 1

[0096] This comparative example provides a fiber membrane, specifically:

[0097] Hydrophobic fiber membrane spinning solution: 12 wt % PVDF-HFP was dissolved in DMF to prepare an electrospinning solution.

[0098] Hydrophilic fiber membrane spinning solution: 14wt% PA6 and 8wt% DTAB were dissolved in formic acid to prepare an electrospinning solution.

[0099] 1) Using glossy paper as a receiving substrate, placing the prepared hydrophobic layer electrospinning solution on an electrospinning pump; setting the electrospinning parameters as follows: voltage 26 kV, receiving distance 25 cm, perfusion speed 2 mL / h, temperature 25° C., relative humidity 90%, and then spinning to obtain a hydrophobic layer fiber membrane;

[0100] 2) The prepared hydrophobic layer fiber membrane is removed as a receiving substrate, and the configured hydrophilic layer electrospinning solution is placed on an electrospinning pump; the electrospinning parameters are set as follows: voltage 26 kV, receiving distance 18 cm, perfusion rate 2 mL / h, temperature 25°C, relative humidity 40%, and then spinning is performed to obtain a composite fiber membrane.

[0101] Comparative Example 2

[0102] This comparative example provides a fiber membrane, specifically:

[0103] Hydrophobic fiber membrane spinning solution: 12 wt % PVDF-HFP and 4 wt % FTES were dissolved in DMF to prepare an electrospinning solution.

[0104] Hydrophilic fiber membrane spinning solution: 14wt% PA6 was dissolved in formic acid to prepare an electrospinning solution.

[0105] S1. Use glossy paper as the receiving substrate and place the prepared hydrophobic layer electrospinning solution on the electrospinning pump; set the electrospinning parameters as follows: voltage 26 kV, receiving distance 25 cm, perfusion speed 2 mL / h, temperature 25 ° C, relative humidity 85%, and then perform spinning to obtain a hydrophobic layer fiber membrane;

[0106] S2. Remove the prepared hydrophobic layer fiber membrane as a receiving substrate, and place the configured hydrophilic layer electrospinning solution on the electrospinning pump; set the electrospinning parameters as follows: voltage 26 kV, receiving distance 18 cm, perfusion speed 2 mL / h, temperature 25 ° C, relative humidity 40%, and then spin to obtain a composite fiber membrane.

[0107] Comparative Example 3

[0108] This comparative example provides a fiber membrane, specifically:

[0109] Hydrophobic layer spinning solution: 12 wt % PVDF-HFP was dissolved in DMF to prepare the electrospinning solution.

[0110] Hydrophilic layer spinning solution: 14 wt% PA6 was dissolved in formic acid to prepare an electrospinning solution.

[0111] S1. Use glossy paper as receiving substrate and place the prepared hydrophobic layer electrospinning solution on an electrospinning pump; set the electrospinning parameters as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 2 mL / h, temperature 25 ° C, relative humidity 90%, and then perform spinning to obtain a hydrophobic layer fiber membrane;

[0112] S2. Remove the prepared hydrophobic layer fiber membrane as a receiving substrate, and place the configured hydrophilic layer electrospinning solution on the electrospinning pump; set the electrospinning parameters as follows: voltage 26 kV, receiving distance 18 cm, perfusion speed 2 mL / h, temperature 25 ° C, relative humidity 40%, and then spin to obtain a composite fiber membrane.

[0113] Comparative Example 4

[0114] This comparative example provides a fiber membrane, specifically: the fluorine-containing polymer is PFA; the hydrophobic membrane thickness is 230 μm, the hydrophobic fiber membrane pore size is 4.2 μm, and the hydrophilic fiber membrane pore size is 0.6 μm.

[0115] This comparative example also provides a method for preparing the above-mentioned radiation refrigeration fiber membrane, comprising the following steps:

[0116] 1) Using glossy paper as a receiving substrate, 14wt% PU and 6wt% PFA were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 25cm, perfusion speed 1mL / h, temperature 25°C, relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0117] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 12wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, perfusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0118] Comparative Example 5

[0119] This comparative example provides a fiber membrane, specifically: the fluorine-containing polymer is PFA; the hydrophobic membrane thickness is 230 μm, the hydrophobic fiber membrane pore size is 4.2 μm, and the hydrophilic fiber membrane pore size is 0.6 μm.

[0120] This comparative example also provides a method for preparing the above-mentioned radiation refrigeration fiber membrane, comprising the following steps:

[0121] 1) Using glossy paper as a receiving substrate, 14 wt% PVDF-HFP and 6 wt% PFA were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 1 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0122] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 12wt% SDS were dissolved in formic acid to prepare an electrospinning solution B, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, perfusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0123] Comparative Example 6

[0124] This comparative example provides a fiber membrane, specifically: the fluorine-containing polymer is PFA; the hydrophobic membrane thickness is 230 μm, the hydrophobic fiber membrane pore size is 4.2 μm, and the hydrophilic fiber membrane pore size is 0.6 μm.

[0125] This comparative example also provides a method for preparing the above-mentioned radiation refrigeration fiber membrane, comprising the following steps:

[0126] 1) Using glossy paper as a receiving substrate, 20 wt% PVDF-HFP and 6 wt% PFA were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 1 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0127] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 12wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, perfusion speed 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0128] Comparative Example 7

[0129] This comparative example provides a fiber membrane, specifically: the fluorine-containing polymer is PFA; the hydrophobic membrane thickness is 230 μm, the hydrophobic fiber membrane pore size is 4.2 μm, and the hydrophilic fiber membrane pore size is 0.6 μm.

[0130] This comparative example also provides a method for preparing the above-mentioned radiation refrigeration fiber membrane, comprising the following steps:

[0131] 1) Using glossy paper as a receiving substrate, 20 wt% PVDF-HFP and 6 wt% PFA were dissolved in DMF to prepare an electrospinning solution A, which was placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25 kV, receiving distance 25 cm, perfusion speed 1 mL / h, temperature 25° C., relative humidity 90%, and then spinning was performed to obtain a hydrophobic layer fiber membrane;

[0132] 2) The prepared hydrophobic layer fiber membrane was removed as a receiving substrate, and 14wt% PA6 and 4wt% DTAB were dissolved in formic acid to prepare an electrospinning solution B and placed on an electrospinning pump; the electrospinning parameters were set as follows: voltage 25kV, receiving distance 15cm, infusion rate 2mL / h, temperature 25°C, relative humidity 40%, and then spinning was performed to obtain a composite fiber membrane.

[0133] Test Case

[0134] The waterproof and moisture-permeable membranes prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were subjected to the following tests, and the data are shown in Table 1.

[0135] Mechanical properties: According to the fabric product standard, 25 pieces of 3mm×3cm rectangular sample fiber membranes were cut from the sample fiber membrane as experimental samples, clamped on the elongation test clamp, and the high-strength stretching software on the computer was opened to set the experimental parameters. The stretching speed was 20mm / min and the clamping distance was 10mm. After preparation, the test was started, and the sample was replaced and the test was repeated 25 times. After the test was completed, the abnormal data was eliminated.

[0136] Air permeability: Cut a 10cm×10cm square sample fiber membrane from the sample fiber membrane and put it into the automatic fabric air permeability tester. After the test is completed, record the data. Move the position of the fiber membrane and continue the test. Repeat this step 5-8 times. After eliminating the abnormal point data, calculate the average value to be the air permeability of the fiber membrane.

[0137] Moisture flux: First, pour about 30mL of deionized water into the moisture permeable cup, cut the sample fiber membrane into a fiber membrane of the same size as the moisture permeable cup, place the fiber membrane on the moisture permeable cup (hydrophobic layer facing down), put on the rubber ring and gasket and fix it with a nut. After fixing, set the instrument parameters: humidity is 50%, constant temperature is 38℃, and air flow speed is 0.44m / s. When the humidity and temperature in the constant temperature box meet the requirements, put in the moisture permeable cup, balance in the constant temperature box for 1h, and quickly weigh the weight of the moisture permeable cup, recorded as m 1 , and then immediately put it into the test instrument for 1 hour, and weigh the weight of the moisture permeable cup again, recorded as m 2 Finally, the moisture permeability flux of each fiber membrane is calculated according to the moisture permeability flux formula WVT= (WVT in the formula represents the moisture permeability flux per square meter per day, kg / m 2 ·d; S(m 2 ) represents the area of ​​the fiber membrane during the test (0.00283m 2 ), Δm(g) represents the mass difference of the same fiber membrane, and t(h) represents the test time of the fiber membrane.

[0138] UV-Vis-NIR (ultraviolet-visible-near infrared) reflectivity test is used to measure the reflectivity of materials within a set wavelength range. The test steps are as follows: prepare the sample to be tested and ensure that the surface is clean and flat; start the UV-Vis-NIR reflectivity test instrument, preheat and calibrate. According to the sample characteristics and test requirements, set the test parameters, such as wavelength range (0μm~2.5μm), power density (0W / m 2 ·nm~2W / m 2·nm), etc. Place the sample to be tested in the test instrument and perform UV-Vis-NIR reflectivity test on the sample according to the set parameters. Record the data during the test, including the curve of reflectivity changing with wavelength.

[0139] Steps for testing infrared emissivity using a Fourier transform infrared spectrometer: Turn on the instrument power and ensure that the instrument is in normal working condition. Prepare the sample to be tested and place it on the sampling system. Adjust the sample position so that the sample is in full contact with the light source to ensure the accuracy of signal acquisition. Start the data acquisition and processing system and enter the spectrum acquisition interface. Set the spectrum acquisition parameters, including the wavenumber range (7μm to 14μm), etc. Finally, click the Start Acquisition button and the system will start to collect and process the spectrum data.

[0140] Water absorption test: Follow GB / T 21655.1-2008 "Evaluation of moisture absorption and quick-drying properties of textiles Part 1: Single combination test method" and other standards. Take five specimens from the sample fabric to be tested, and the size of each specimen is at least 10cm×10cm. The specimens are humidified and balanced under standard atmospheric conditions to ensure the accuracy of the test results. Put the specimens in a container filled with grade 3 water, and the specimens will sink naturally after absorbing water. After wetting in water for 5 minutes, take them out and hang them vertically flat and naturally to let the water drip naturally. When the specimen stops dripping, take out the specimen and weigh it. The water absorption rate of the specimen is equal to the ratio of the difference between the mass after soaking and the original mass to the original mass. Calculate the average of the five specimens as the final result.

[0141] Water evaporation rate test: Take five samples from the sample cloth to be tested, and the size of each sample is at least 10cm×10cm. Weigh each sample and record it as m0. Wet the sample according to the drip diffusion time test method. Weigh the wetted sample immediately and hang it naturally in the standard atmosphere. Weigh the mass every 5 minutes until the difference in continuous weighing does not exceed 1%, and obtain the water evaporation amount and time of the sample at each moment.

[0142] Table 1 Performance test results of Examples 1 to 4 and Comparative Examples 1 to 7

[0143]

[0144]

[0145] According to the above Table 1, the fiber membranes provided by Examples 1 to 4 of the present invention have high water content, moisture permeability, high elongation, excellent radiation cooling effect and moisture absorption and perspiration capacity through the synergy between the PVDF-HFP / fluoropolymer hydrophobic fiber membrane and the PA6 / DTAB hydrophilic fiber membrane.

[0146] From comparative example 1, the hydrophobic layer of the prepared fiber membrane does not have the addition of fluoropolymer, and the reflectivity and emissivity are obviously low, and the radiation cooling effect is poor. From comparative example 2, the hydrophilic layer of the prepared fiber membrane does not have the addition of DTAB, and there is no oriented structure. The evaporation time is long, the hydrophilic effect is poor, and the overall moisture absorption and perspiration effect is poor. From comparative example 3, the hydrophobic layer does not have the addition of fluoropolymer, and the hydrophobicity and radiation cooling effects are poor, and the hydrophilic layer does not have the addition of DTAB, and the hydrophilic effect is significantly reduced, and the overall composite fiber membrane performance is low. In comparative example 4, PU does not contain fluorine, so the hydrophobicity and radiation cooling effects are slightly worse, and the moisture absorption and perspiration ability is also weaker. From comparative example 5, SDS replaces DTAB, the hydrophilic effect decreases, the moisture absorption and perspiration performance decreases, and no oriented structure is produced. In comparative example 6, the concentration of PVDF-HFP is too high, and the fiber has obvious beads, the morphology deteriorates, the mechanical properties deteriorate, and the fiber thickness is uneven, which affects its overall performance. In Comparative Example 7, the concentration of DTAB is too low, the oriented structure is not obvious, the hydrophilic effect is poor, and the moisture absorption and perspiration removal effect is reduced.

[0147] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A radiative cooling fiber membrane with a wetting gradient, characterized in that: The radiation refrigeration fiber includes a hydrophobic fiber membrane and a hydrophilic fiber membrane; The raw materials for preparing the hydrophobic fiber membrane include polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer; the raw materials for preparing the hydrophilic fiber membrane include polyamide and dodecyltrimethylammonium bromide.

2. The radiation cooling fiber membrane according to claim 1, characterized in that: The average pore size of the hydrophobic fiber membrane is 1.0 μm to 4.5 μm; preferably, the average pore size of the hydrophilic fiber membrane is 0.15 μm to 0.75 μm; preferably, the average pore size of the hydrophobic fiber membrane is larger than the average pore size of the hydrophilic fiber membrane.

3. The radiation cooling fiber membrane according to claim 1, characterized in that: The fluorine-containing polymer includes at least one of perfluorodecyltriethoxysilane, perfluorooctyltriethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, dodecafluoroheptylpropyltrimethoxysilane, hexafluorobutylpropyltrimethoxysilane, fluorine-containing polyurethane, fluorine-containing polyimide, fluorine-containing polyacrylate, fluorinated ethylene-propylene copolymer, fluorinated ethylene-propylene copolymer and perfluoroalkoxy resin.

4. The radiation cooling fiber membrane according to claim 1, characterized in that: The thickness of the hydrophobic fiber membrane is 200 μm to 240 μm; preferably, the thickness of the hydrophilic fiber membrane is 70 μm to 100 μm.

5. A method for preparing the radiation cooling fiber membrane according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: S1, mixing polyvinylidene fluoride-hexafluoropropylene and a fluorine-containing polymer into a spinning solution A, and electrospinning to obtain a hydrophobic fiber membrane; S2. Using the hydrophobic fiber membrane as a spinning substrate, mixing polyamide and dodecyltrimethylammonium bromide into a spinning solution B, and electrospinning to obtain a hydrophilic fiber membrane, thereby obtaining the radiation refrigeration fiber membrane.

6. The preparation method according to claim 5, characterized in that: In step S1, the concentration of polyvinylidene fluoride-hexafluoropropylene in the spinning solution A is 12wt% to 18wt%; preferably, in step S1, the concentration of the fluorine-containing polymer in the spinning solution A is 3wt% to 15wt%.

7. The preparation method according to claim 5, characterized in that: In step S2, the concentration of polyamide in the spinning solution B is 12wt% to 16wt%; preferably, in step S2, the concentration of dodecyltrimethylammonium bromide in the spinning solution B is 8wt% to 14wt%.

8. The preparation method according to claim 5, characterized in that: In step S1, the electrospinning voltage is 25kV to 30kV; preferably, in step S1, the electrospinning receiving distance is 23cm to 25cm; preferably, in step S1, the electrospinning perfusion speed is 1 to 3mL / h; preferably, in step S1, the electrospinning temperature is 25°C to 27°C; preferably, in step S1, the electrospinning relative humidity is 80% to 90%.

9. The preparation method according to claim 5, characterized in that: In step S2, the electrospinning voltage is 25kV to 30kV; preferably, in step S2, the electrospinning receiving distance is 20cm to 23cm; preferably, in step S2, the electrospinning perfusion speed is 1 to 2mL / h; preferably, in step S2, the electrospinning temperature is 25°C to 27°C; preferably, in step S2, the electrospinning relative humidity is 40% to 45%.

10. Use of the radiation cooling fiber membrane according to any one of claims 1 to 4 in the fields of personal protection, professional equipment, sportswear and medical supplies.

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