Infrared high-transmission fiber film, preparation method and application thereof

Abstract

The application provides an infrared high-transmittance fiber film and a preparation method and application thereof, and belongs to the technical field of radiation refrigeration materials. The PA6 fiber film with high infrared transmittance is prepared through an electrostatic spinning process, the high drafting action of electrostatic force, and the microsecond evaporation rate of a solvent, and the molecular chains are induced to be orderly arranged. The PA6 in the fiber film prepared by the application is mainly in the form of gamma crystal, the gamma crystal accounts for 10-25%, the infrared radiation transmittance of the fiber film is 65-90% when the thickness is 50-150 mu m, the fiber film can be applied to personal thermal management technology, the infrared radiation generated by the human body is transmitted through the transmission of thermal radiation, the heat dissipation process of the human body is maximized, the thermal comfort state of the human body can be adjusted, the energy consumption of an indoor power system is reduced, and the diversity of raw materials of infrared high-transmittance fabrics is enriched.

Description

Technical Field

[0001] This invention relates to the field of radiation cooling materials technology, specifically to an infrared high-transmittance fiber membrane, its preparation method, and its application. Background Technology

[0002] Globally, 40% of total annual energy consumption is used in buildings, and of that building energy consumption, over 50% is used for indoor cooling, heating, and ventilation systems. While a large amount of energy is invested, a significant portion of this energy is not effectively utilized. Take cooling as an example: cooling, a major contributor to building energy consumption, primarily relies on electricity to drive air conditioning for temperature reduction. However, air conditioning, as a traditional and common cooling method, is inherently energy-intensive and inefficient. This is because, during operation, air conditioners consume a large amount of electricity to cool the entire space, while the actual cooling need is only felt by individuals. Therefore, more efficient thermal control methods are needed to address the inefficiency of traditional spatial cooling models.

[0003] Personal thermal management technology emphasizes creating a localized microenvironment around the human body to regulate thermal comfort, effectively reducing reliance on air conditioning. Statistics show that raising the air conditioning set temperature by 2°C in summer can save 20% of air conditioning energy consumption. Therefore, personal thermal management strategies can effectively reduce the energy consumption of indoor electrical systems.

[0004] Since humans primarily exchange heat indoors through radiation, conduction, and convection, with radiation accounting for over 50%, regulating human heat radiation is crucial. When the skin emits and transmits heat radiation flux as electromagnetic waves in the mid-infrared range into the environment, clothing, as the first and most important barrier, directly influences this transmission process. Currently, radiation-cooling fabrics mainly include two types: infrared-emitting and infrared-transmitting fabrics. Infrared-transmitting fabrics, due to their ability to reduce obstacles in the heat radiation transmission process, maximize heat dissipation from the human body and are therefore superior to infrared-emitting fabrics.

[0005] Currently, the vast majority of infrared-transmitting fabrics are limited to polyethylene (PE). This is because the vibrational process of molecular bonds generates infrared absorption, and polyethylene molecules, apart from the main chain, do not have any side chain groups, thus inherently not producing excessive infrared light absorption. However, as an engineering plastic, polyethylene (PE) is not widely used in the textile industry. Furthermore, the chemical inertness and difficulty in dyeing and processing polyethylene also limit the further development of high-transmittance infrared fabrics. To enrich the diversity of raw materials for high-transmittance infrared fabrics, it is essential to use other materials, especially textile materials, to achieve high infrared transmittance characteristics in fabrics.

[0006] Nylon 6 (PA6), a common textile raw material, has a relatively simple molecular chain structure. Although it has additional amide groups (-CO-NH-) compared to PE, the vibrational absorption sites of its molecular bonds largely avoid the concentrated region of human radiation flux (7–14 μm), making it very promising for achieving infrared transmission characteristics. However, commercially available PA6 materials exhibit high infrared emission at varying fabric thicknesses. This anomaly indicates that, even with a fixed molecular chain structure, other influencing factors still constrain the infrared vibrational process and cause spectral differences. Therefore, clarifying the factors affecting the infrared transmission performance of PA6 is crucial. Summary of the Invention

[0007] In view of the technical problems existing in the background art, this application provides an infrared high-transmittance fiber membrane, its preparation method and application, aiming to solve the problem that existing radiation cooling materials are limited in variety and difficult to apply in the textile field.

[0008] In one aspect, this application provides an infrared high-transmittance fiber membrane, wherein the fiber membrane contains PA6 whose main crystal form is γ crystal.

[0009] In the technical solution of this application embodiment, the hydrogen bond arrangement of γ crystal is sparser and the interaction force is weaker, resulting in a lower intensity of chemical bond infrared vibration and enabling high transmittance of infrared radiation.

[0010] In some embodiments, the γ-crystalline form accounts for 10–25% of PA6.

[0011] In this embodiment, the high proportion of γ-type crystals results in more low-vibrational-intensity chemical bonds in the molecule, and better infrared radiation transmittance of the fiber membrane.

[0012] In some embodiments, when the thickness of the fiber membrane is 50–150 μm, the infrared radiation transmittance is 65–90%.

[0013] In this embodiment, the fiber membrane containing PA6, whose main crystal form is γ, still has a high infrared radiation transmittance even when it is relatively thick.

[0014] Secondly, embodiments of this application provide a method for preparing an infrared high-transmittance fiber membrane, comprising the following steps:

[0015] S1. Add PA6 powder to a mixed solution of formic acid and acetic acid, stir to dissolve, and obtain an electrospinning solution;

[0016] S2. Electrospin the electrospinning solution to obtain an infrared high-transmittance fiber membrane.

[0017] In the technical solution of this application embodiment, a PA6 fiber membrane with high infrared transmittance is prepared by inducing the orderly arrangement of molecular chains through the high stretching effect of electrostatic force and the microsecond-level evaporation rate of solvent.

[0018] In some embodiments, in step S1, the volume ratio of formic acid to acetic acid is 1:1; and the concentration of PA6 powder in the electrospinning solution is 0.1–0.3 g / ml.

[0019] In this embodiment, a PA6 fiber membrane with a predominantly γ-crystalline form is obtained by combining a spinning solution of a specific concentration with spinning conditions.

[0020] In some embodiments, in step S2, the electrospinning voltage is 18-22KV positive voltage and -5-3KV negative voltage; the electrospinning solution push speed is 0.08-0.12ml / h; during the electrospinning process, the collector rotation speed is 78-82rpm; and the spinning needle is No. 18.

[0021] In this embodiment, by controlling the electrospinning conditions and the fiber stretching, an infrared high-transmittance fiber membrane containing PA6 mainly in the γ-crystalline form is obtained.

[0022] Thirdly, embodiments of this application provide an application of an infrared high-transmittance fiber membrane, applied to radiation-cooled fabrics.

[0023] In the technical solution of this application embodiment, the infrared high-transmittance fiber membrane has good wearability and dyeability, and can be applied to the clothing field.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] Figure 1 The image shows the X-ray diffraction spectrum of the infrared high-transmittance fiber membrane prepared in Example 1.

[0026] Figure 2 This is a human wear experiment diagram of the infrared high-transmittance fiber membrane prepared in Example 1.

[0027] Figure 3 The results are simulated human skin test results of the infrared high-transmittance fiber membranes prepared in Example 1 and Comparative Examples 2-4.

[0028] Figure 4 The images show the X-ray diffraction spectra of the infrared high-transmittance fiber membranes prepared in Examples 2-3 and Comparative Examples 5-6. Detailed Implementation

[0029] The embodiments of the technical solution of this application are described in detail below. These embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore merely examples and should not be used to limit the scope of protection of this application.

[0030] 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 application belongs; the terms “comprising” and “having” and any variations thereof as used herein are for the purpose of describing particular embodiments only and are not intended to limit this application.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] To address the limitations of existing radiation cooling materials, which are often limited in variety and difficult to apply in the textile industry, this application provides an infrared high-transmittance fiber membrane, its preparation method, and its applications. Specifically, this application discovers that PA6, as a semi-crystalline material, has two main crystal forms: α-crystal and γ-crystal. The α-crystal, with its antiparallel molecular chains in a straight-chain conformation, is the most stable crystal form. The γ-crystal, on the other hand, has parallel helical molecular chains and is a metastable crystal form. The α-crystal has denser and stronger hydrogen bonds, while the γ-crystal has sparser and weaker hydrogen bonds. Furthermore, the infrared vibration intensity of the chemical bonds in the α-crystal is significantly higher than that in the γ-crystal. Therefore, given the same number of chemical bonds, α-crystal PA6 exhibits stronger infrared vibration absorption performance than γ-crystal PA6. Thus, to achieve infrared transmission, both the number and quality (strength) of molecular bonds must be minimized. This application utilizes a highly drawn electrospinning process accompanied by a rapid solvent evaporation process to induce an ordered arrangement of molecular chains, resulting in a PA6 fiber membrane dominated by the γ-crystal form. Since the γ crystal form is a metastable phase, there is a tendency for the γ crystal to transform into the α crystal form during the process. However, due to the rapid evaporation of the solvent, the fiber solidifies quickly, and the entire molding process ends before the crystal form transformation occurs, thus producing an infrared high-transmittance fiber membrane with high infrared transmittance.

[0033] On the one hand, this application provides an infrared high-transmittance fiber membrane, wherein the fiber membrane contains PA6 whose main crystal form is γ crystal.

[0034] In the technical solution of this application embodiment, the hydrogen bond arrangement of γ crystal is sparser and the interaction force is weaker, resulting in a lower intensity of chemical bond infrared vibration and enabling high transmittance of infrared radiation.

[0035] Furthermore, in some embodiments, the γ-form accounts for 10-25% of PA6.

[0036] In the technical solution of this application embodiment, the high proportion of γ crystal form results in more chemical bonds with low vibrational intensity in the molecule, and better infrared radiation transmittance of the fiber membrane.

[0037] Furthermore, in some embodiments, when the thickness of the fiber membrane is 50–150 μm, the infrared radiation transmittance is 65–90%.

[0038] In the technical solution of this application embodiment, the fiber membrane containing PA6 with the main crystal form being γ crystal has a high infrared radiation transmittance even when it is relatively thick.

[0039] Secondly, embodiments of this application provide a method for preparing an infrared high-transmittance fiber membrane, comprising the following steps:

[0040] S1. Add PA6 powder to a mixed solution of formic acid and acetic acid, stir to dissolve, and obtain an electrospinning solution;

[0041] S2. Electrospin the electrospinning solution to obtain an infrared high-transmittance fiber membrane.

[0042] In the technical solution of this application embodiment, a PA6 fiber membrane with high infrared transmittance is prepared by inducing the orderly arrangement of molecular chains through the high stretching effect of electrostatic force and the microsecond-level evaporation rate of solvent.

[0043] Furthermore, in some embodiments, in step S1, the volume ratio of formic acid to acetic acid is 1:1; and the concentration of PA6 powder in the electrospinning solution is 0.1–0.3 g / ml.

[0044] In the technical solution of this application embodiment, a PA6 fiber membrane mainly in the γ crystal form is obtained by combining a spinning solution of a specific concentration with spinning conditions.

[0045] Furthermore, in some embodiments, in step S2, the electrospinning voltage is 18-22KV positive voltage and -5-3KV negative voltage; the electrospinning solution push speed is 0.08-0.12ml / h; during the electrospinning process, the collector rotation speed is 78-82rpm; and the spinning needle is No. 18.

[0046] In the technical solution of this application embodiment, by controlling the electrospinning conditions and controlling the fiber stretching, an infrared high-transmittance fiber membrane containing PA6 mainly in the γ crystal form is obtained.

[0047] Thirdly, embodiments of this application provide an application of an infrared high-transmittance fiber membrane, applied to radiation-cooled fabrics.

[0048] In the technical solution of this application embodiment, the infrared high-transmittance fiber membrane has good wearability and dyeability, and can be applied to the clothing field.

[0049] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0050] Example 1

[0051] This embodiment provides a method for preparing an infrared high-transmittance fiber membrane, which specifically includes the following steps:

[0052] Measure 50 ml of formic acid and acetic acid separately, pour them into glass containers, and stir well. Then weigh 10 g of PA6 powder, pour it into the glass container, and stir until PA6 is completely dissolved to obtain a spinning solution. Pour the prepared spinning solution into the spinning electrode frame of an electrospinning machine, and perform electrospinning using an 18-gauge spinning needle under the conditions of 20 kV positive voltage, -4 kV negative voltage, solution push rate of 0.1 ml / h, and collector rotation speed of 80 rpm to obtain an infrared high-transmittance fiber membrane (i.e., IRT-PA6).

[0053] The X-ray diffraction spectrum of the infrared high-transmittance fiber membrane prepared in this embodiment is as follows: Figure 1 As shown. By Figure 1 The peak shape in the sample indicates that the γ-crystalline PA6 accounts for 20% of the infrared high-transmittance fiber membrane prepared in this embodiment.

[0054] Human wear experiment was conducted on the infrared high-transmittance fiber membrane prepared in Example 1, and the test results are as follows: Figure 2 As shown. Figure 2 In this context, "Cotton" represents cotton fabric, "IRT-PA6" represents the infrared high-transmittance fiber membrane prepared in this embodiment, and "Ambient" represents the test environment temperature. Figure 2 It can be seen that the infrared high-transmittance fiber membrane prepared in this embodiment can achieve a cooling advantage of about 2°C compared with cotton.

[0055] Comparative Examples 2-4

[0056] Comparative Examples 2–4 were provided with nano PE film, commercial PA6 fabric, and cotton fabric, respectively, and their cooling performance was tested.

[0057] The nano-PE film, commercial PA6 fabric, and cotton fabric were all purchased commercially. The nano-PE film is infrared transmissive with an infrared transmittance of nearly 80%, while the commercial PA6 fabric (5% gamma crystal) and cotton fabric are both infrared emissive with an infrared emissivity of approximately 90%.

[0058] The results of simulated human skin tests in Example 1 and Comparative Examples 2-4 are as follows: Figure 3 As shown.

[0059] Depend on Figure 3 The test results of Example 1 and Comparative Examples 2-4 show that the infrared high-transmittance fiber membrane prepared in Example 1 can achieve a cooling effect similar to that of commercial nano-PE membranes, and can achieve a cooling advantage of 2-3℃ compared with commercial PA6 fabrics and cotton fabrics.

[0060] Examples 2-3 and Comparative Examples 5-6

[0061] Examples 2-3 and Comparative Examples 5-6 respectively provide a method for preparing an infrared high-transmittance fiber membrane. Compared with Example 1, the difference lies in the concentration of the spinning solution and the spinning conditions (voltage, spinning solution push speed, collector speed). The other steps are roughly the same as in Example 1, and will not be repeated here.

[0062] The concentration of the spinning solution and spinning conditions (voltage, spinning solution push speed, collector speed) for preparing infrared high-transmittance fiber membranes in Examples 2-3 and Comparative Examples 5-6 are shown in Table 1.

[0063] Table 1 shows the concentration of the spinning solution and spinning conditions (voltage, spinning solution speed, collector speed) for preparing infrared high-transmittance fiber membranes in Examples 2-3 and Comparative Examples 5-6.

[0064]

[0065] The X-ray diffraction spectra of the infrared high-transmittance fiber membranes prepared in Examples 2-3 and Comparative Examples 5-6 are as follows: Figure 4 As shown.

[0066] Depend on Figure 4 The X-ray diffraction spectra of Examples 2 and 3 show that when the spinning solution concentration is 0.1–0.3 g / ml, and the spinning positive and negative voltage, spinning solution push rate, and collector rotation speed are within the ranges of 18–22 kV, -5–-3 kV, 0.08–0.12 ml / h, and 78–82 rpm, respectively, the proportion of PA6 in the γ-crystalline form of the infrared high-transmittance fiber membrane is relatively high. The X-ray diffraction spectra of Comparative Examples 5 and 6 show that excessively high or low spinning positive and negative voltages and spinning solution concentrations affect the proportion of the γ-crystalline form in the infrared high-transmittance fiber membrane, ultimately affecting the infrared transmittance value.

[0067] In summary, this application provides an infrared high-transmittance fiber membrane, its preparation method, and its application, belonging to the field of radiation cooling materials technology. Through electrospinning, utilizing the high stretching effect of electrostatic force and the microsecond-level evaporation rate of the solvent, the molecular chains are induced to arrange in an orderly manner, thus preparing a PA6 fiber membrane with high infrared transmittance. In the fiber membrane prepared in this application, PA6 is mainly in the γ-crystalline form, accounting for 10-25%. When the thickness of the fiber membrane is 50-150 μm, the infrared radiation transmittance is 65-90%, which can be applied to personal thermal management technology. By transmitting infrared radiation generated by the human body through heat radiation transfer, the heat dissipation process of the human body is maximized. This not only regulates the thermal comfort state of the human body and reduces the energy consumption of indoor electrical systems, but also enriches the diversity of raw materials for infrared high-transmittance fabrics, and can be applied to radiation cooling fabrics.

[0068] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An infrared high-transmittance fiber membrane, characterized in that, The fiber membrane contains PA6, whose main crystal form is γ-crystal. The γ-crystalline form accounts for 10-25% of the PA6; When the thickness of the fiber membrane is 50~150μm, the infrared radiation transmittance is 65~90%; The method for preparing the infrared high-transmittance fiber membrane includes the following steps: S1. Add PA6 powder to a mixed solution of formic acid and acetic acid, stir to dissolve, and obtain an electrospinning solution; the volume ratio of formic acid to acetic acid is 1:1; the concentration of PA6 powder in the electrospinning solution is 0.1~0.3g / ml; S2. Electrospin the electrospinning solution to obtain an infrared high-transmittance fiber membrane; The electrospinning voltage is 18~22KV positive voltage and -5~-3KV negative voltage.

2. The infrared high-transmittance fiber membrane according to claim 1, characterized in that, In step S2, during electrospinning, the push rate of the electrospinning solution is 0.08~0.12 ml / h.

3. The infrared high-transmittance fiber membrane according to claim 1, characterized in that, In step S2, the collector used during electrospinning rotates at a speed of 78-82 rpm.

4. The infrared high-transmittance fiber membrane according to claim 1, characterized in that, In step S2, the spinning needle used during electrospinning is a No. 18 needle.

5. An application of an infrared high-transmittance fiber membrane, characterized in that, The infrared high-transmittance fiber membrane according to any one of claims 1 to 4 is applied to radiation-cooled fabrics.

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