CN114059233B - Transparent nanofiber membrane, preparation method thereof and application of transparent nanofiber membrane to transparent mask - Google Patents

Abstract

The invention relates to a transparent nanofiber film and its preparation and application on transparent masks. The preparation method comprises the following steps: using an electrospinning process and a special receiving base material to make a high molecular polymer into a transparent nanofiber film; The base material refers to an insulating base material with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure formed by connecting a regular hexagonal support and three inline supports, and three inline supports. One end of the bracket meets at the center of the regular hexagonal bracket, and the other end is respectively connected with the three non-adjacent vertices of the regular hexagonal bracket; the special receiving base material is wrapped on the peripheral surface of the grounded roller; finally The average thickness of the prepared transparent nanofiber film is 1-20 μm, and the average thickness of the main part is 0.2-4 μm; the fibers of the main part are arranged in a certain orientation, and the degree of orientation is greater than 80%; the application is: used for making transparent masks . The method of the invention is simple, and the prepared fiber film has high transparency and high porosity.

Description

A kind of transparent nanofiber membrane and its preparation and application in transparent mask

technical field

The invention belongs to the technical field of masks, and relates to a transparent nanofiber film and its preparation and application on transparent masks.

Background technique

Flexible, transparent films or fibrous films or substrates have attracted extensive attention in the fields of smart wear, electronic skin, air filtration, biomedical, and personal protection. Traditional transparent films or substrates, such as glass and polyester (PET), polyethylene (PE) plastics, etc., cannot fully meet the needs of emerging application fields that require excellent adsorption, air permeability (large specific surface area) , high porosity) and flexible transparent materials. For example, smart wearables or electronic skins are becoming more and more popular, and the existing transparent film materials cannot show high light transmittance and good air permeability at the same time; air pollution causes serious harm to human health, and the existing filter materials have high filtration performance, However, the light transmission performance is poor; especially in the field of personal protection, due to the outbreak and spread of the new crown pneumonia epidemic in recent years, people all over the world are suffering from the epidemic. The masks made of fiber membrane materials are the most simple, effective and common The personal protective equipment used has played an irreplaceable role in the fight against the epidemic, because many infectious diseases are transmitted through airborne pollution particles as carriers, and masks can effectively intercept airborne particles. However, the existing fiber membrane material masks are opaque, which brings inconvenience to people's daily life (affects the mobile phone to brush the face, the station face recognition system), and also affects the communication between doctors and patients. Existing transparent masks are all prepared from solid transparent plastic plates (PE, PP, PC, etc.), which have poor air permeability and poor protection effect.

In recent years, new transparent materials have attracted much attention, and transparent and flexible nanopapers prepared from cellulose or chitin nanofibers have been developed. The obtained nanopaper has high light transmittance and good mechanical properties, and is expected to replace traditional plastic films. However, the preparation process of nanopaper involves complex chemical treatments, and the material has low or no porosity and poor air permeability. Wood has been widely used for many years due to its excellent properties, and transparent wood materials have also been reported. After chemical treatment, the transparent film prepared by mechanical pressure or resin filling has high transparency and other excellent properties, which are superior to traditional glass. However, the transparent wood film material is solid, loses the structural advantage of wood itself, lacks interconnected pores, and the preparation process requires complex chemical processes, which consumes energy and time. Therefore, it is a great challenge and an urgent need to prepare transparent membrane materials with excellent adsorption, gas permeability (large specific surface area, high porosity) and flexibility by a low-cost and simple method.

Electrospinning technology allows the easy preparation of continuous micro- or nanofibers from different materials (polymers, carbon, ceramics, etc.) The electrospun fiber membrane thus prepared has small pores, high porosity, large specific surface area, excellent flexibility and robust mechanical properties. However, the transparentization of electrospun fiber membranes is extremely difficult due to the severe light reflection and scattering of microfibers and nanofibers. There have been many reports on the preparation of electrospun transparent fiber membranes, which can be divided into two categories: one is to fill the polymer into the fiber membrane, which can generate transparent nanocomposites; Resin is added to electrospun nylon-4,6 film; nylon-6 nanofiber film is filled with cellulose acetate; polyacrylonitrile (PAN)/polyurethane (PU) composite nanofiber film heats and melts PU to obtain transparency; this achieves transparent fibers The membrane method loses the fiber structure and pores, and the micro or nano fibers only play a reinforcing role; the other is to reduce the thickness of the electrospun fiber membrane; the thinner the fiber membrane, the higher the light transmittance; for example, combined with electrospinning /mesh technology to fabricate ultra-thin nanofibers or nanoarachnoid air filters with high performance; however, its disadvantages are poor mechanical properties and harsh process conditions, which means that the thickness of nanoarachnoid is around 30nm, which is too thin, It cannot be used independently, and the preparation takes a long time. In conclusion, the existing methods for preparing transparent electrospinning fiber membranes are complicated and lose the advantages of fiber membranes.

Therefore, developing transparent electrospun fibrous membranes with high light transmittance, high porosity and self-supporting remains a great challenge.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the present invention provides a transparent nanofiber film and its preparation and application on a transparent mask. The present invention designs and prepares transparent nanofiber membrane materials with high light flux structure for the first time, and on this basis, prepares transparent fiber membrane masks. The prepared series of transparent fiber membranes have excellent light transmittance (up to 96%). , high porosity (greater than or equal to 80%), the prepared transparent mask has excellent light transmittance (greater than or equal to 80%) and PM _0.3 filtration performance (filtration efficiency greater than 90%, piezoresistance less than 100Pa).

For achieving the above object, the scheme that the present invention adopts is as follows:

A method for preparing a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate (generally made of polyamide and polyester) with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is composed of a regular hexagonal bracket and three The planar structure formed by the connection of the zigzag brackets, one end of the three zigzag brackets meets at the center of the regular hexagonal bracket, and the other ends are respectively connected with the three vertices of the hexagonal bracket, and the three vertices are the Non-adjacent vertices on a regular hexagonal bracket;

The special receiving substrate is covered on the peripheral surface of the roller (it can be completely covered or only partially covered, the special receiving substrate can be fixedly connected with the roller by gluing or other means), and the roller is grounded, so that the needle tip is An electric field is formed between the drum and the drum, which rotates with a special receiving substrate to deposit fibers evenly on the substrate.

As the preferred technical solution:

The above-mentioned preparation method of a transparent nanofiber membrane, the side length of the regular hexagon is 1.0～2.5mm (preferably 1.50mm); the thicknesses of the regular hexagon support and the inline support are both 100～200 μm (preferably 150 μm) , if the cross-section of the stent is circular, the thickness is the diameter of the circle, and if the cross-section of the stent is square, the thickness is the side length of the square).

The above-mentioned preparation method of a transparent nanofiber film, the high molecular polymer is polyurethane (PU), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), cellulose acetate (CA), polymethacrylic acid Methyl ester (PMMA), polyamide (PA), polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyethylene oxide (PEO), chitosan and carapace more than one of the elements.

The above-mentioned preparation method of a transparent nanofiber membrane, the parameters of electrospinning are: the concentration of the spinning solution is 8-11wt%, the perfusion speed is 0.3-1.0ml/h, the spinning voltage is 10-25kV, The rotating speed of the drum is 40-60rpm, the receiving distance is 10-20cm, the temperature is 25±2°C, and the relative humidity is 35-45%.

The present invention also provides a transparent nanofiber film prepared by the above-mentioned preparation method of a transparent nanofiber film. The transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is that the nanofibers are arranged in a special manner. The regular hexagonal structure formed by the method, the special arrangement means: the fibers in the basic unit II are divided into three parts, the fibers at the edge of the regular hexagonal structure are recorded as the first part, and the center of the regular hexagon is recorded as the first part. The fibers on the three connecting lines to the three non-adjacent vertices of the regular hexagon are recorded as the second part, and the fibers in the remaining positions are recorded as the third part;

The average thickness of the transparent nanofiber film is 1-20 μm, and the average thickness of the fiber film in the third part is 0.2-4 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is greater than 80%;

The test method for the average thickness is: use the CHY-C2 thickness gauge to test the thickness of the fiber film, cut the sample into 10 × 10cm, the pressure is 0.5kPa, and evenly select 10 points on the surface of the sample for the thickness test, and finally find get the average thickness;

The test method for the degree of orientation is: calculate the birefringence by measuring the birefringence with an optical microscope;

The projected area of the fibers of the third portion is 60% or more of the projected area of the basic unit II.

As the preferred technical solution:

In the above-mentioned transparent nanofiber film, the fibers of the first part are arranged in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure (that is, the direction at the edge of the regular hexagonal structure). The fibers, on the edge of a certain side, are parallel to which side), the fibers of the second part are arranged in the orientation direction of B, and B is the direction parallel to each connection line (that is, in the regular hexagon's direction). The fibers on the three connecting lines between the center and the three non-adjacent vertices of the regular hexagon are parallel to which connecting line).

In the transparent nanofiber film as described above, the average diameter of the nanofibers is 200 nm.

The above-mentioned transparent nanofiber film, the light transmittance of the transparent nanofiber film is 50-96%, the porosity is 80-92%, and the tensile strength is 25-30MPa;

The test method of light transmittance is as follows: use an ultraviolet-visible light spectrophotometer to test the film as a whole.

The test method of porosity is: P=[(V ₀ -V)/V ₀ ]×100%=[1-V/V ₀ ]×100%; wherein, P is the porosity, %; V ₀ is the material in the The volume in the natural state, or the apparent volume, cm ³ or m ³ ; V is the absolute compact volume of the material, cm ³ or m ³ ;

The test method of tensile strength is: use the universal strength testing machine to test.

The present invention also provides the application of the above-mentioned transparent nanofiber film on a transparent mask, the transparent mask has a three-layer structure, the middle layer is composed of a transparent nanofiber film, and the upper and lower layers are both determined by light transmittance (the test method is the same as above) The transparent gauze mesh is composed of more than 96%, and the thickness of the transparent gauze mesh is 50-200 μm.

As the preferred technical solution:

The above-mentioned application, the transmittance (test method is the same as above) of the transparent mask is greater than 45%, and during PM _0.3 filtration performance test, the filtration efficiency is greater than 90%, and the piezoresistance is less than 100Pa; The test method of filtration efficiency and piezoresistance refers to GB2626-2006.

The principle of the present invention is as follows:

The present invention is created as "a transparent nanofiber membrane mask and its preparation method", using electrospinning technology and a self-designed receiving substrate to prepare a highly transparent nanofiber membrane in one step (as shown in Figure 1), here On this basis, a transparent fiber membrane mask with excellent PM _0.3 filtration performance was prepared by using a transparent nanofiber membrane.

The self-designed receiving substrate in this method has special structural features (as shown in Figures 2 and 3), and is composed of two parts: the first part is a regular hexagonal frame, and the second part is a herringbone frame. This special structural feature determines that the prepared fiber membrane has a special high light flux structure, thereby achieving high light transmittance. The raw material of the receiving substrate is polyamide 6 or polyester material, with a thickness of 150 μm and a side length of 1.50 mm.

The transparent fiber film prepared by this method has a high luminous flux structure (as shown in Figure 4), which consists of three parts: the first part is a regular hexagon formed by concentrated accumulation of fibers, and the second part is a herringbone shape formed by concentrated accumulation of fibers , the third part is the area where the fibers are stacked between the regular hexagon and the chevron. Thick ones represent more fiber accumulation, and thin ones represent less fiber accumulation. At the same time, the fibers are highly oriented in all three parts.

The forming process of the fiber film is closely related to the distribution of the electric field, and different structures of the substrate have different influences on the electric field. As shown in Figure 5, the simulation diagrams of the electric field distribution in the electric field of the rectangular frame, the regular hexagonal frame and the substrate in the method are respectively shown, from which it can be seen that the electric field is mainly distributed in the middle of the rectangular frame and the regular hexagonal frame In contrast, on the receiving substrate designed in the present invention, the electric field is more distributed on the nine frames and less distributed among the frames, which leads to Therefore, the fibers are concentrated on the frame, and the area between the frames has a small amount of fibers, so that the light mainly passes through this area, so as to obtain high transparency. The electron micrographs in FIG. 5 are the fiber membranes obtained from the above three substrates with different structures, respectively.

The fibers are highly oriented in the third part, which may be due to the formation of a special electric field in the region between the frames (as shown in Fig. 6). When the positively charged jet approaches the receiving substrate, electrostatic forces, i.e. Coulomb force, are created between the oppositely charged fiber jet and the grounded receiving substrate surface, resulting in opposite directions due to the interaction of electric field lines and Coulomb forces The electrostatic tensile force is distributed in parallel between the two electrodes. This causes the fibers to be stretched between the two electrodes and arranged in parallel between the two electrodes at a certain angle, thereby forming an oriented fiber structure.

The principle of the high transparency of the fiber membrane structure is: first, the fibers are mainly distributed on the regular hexagon and the herringbone, and a small amount is distributed in the area between the two. According to Fermat's theorem - light propagates along the shortest distance. , when the light irradiates the surface of the fiber film, the light will preferentially pass through the third part with less fiber content and thin thickness, which greatly reduces the transmission loss of light; secondly, the fibers are oriented in each part, and the orientation structure It will reduce the multi-level reflection of light, shorten the effective propagation path of light, and be beneficial to the maintenance of light intensity.

Compared with the fiber film of the prior art, the fiber film of the present invention is more transparent under the premise of the same thickness, because:

The surface roughness of the fiber film of the prior art is very large, and the light is strongly reflected, which makes most of the fibers appear white. In addition, the fiber membrane is a mixture of polymer fibers and a large amount of air. Due to the difference between the refractive index of the fiber itself and the refractive index of air, interface reflection will occur at the interface between the fiber and the air, which is manifested as light scattering inside the fiber membrane. , the greater the difference in refractive index and the more air content, the more serious the scattering inside the fiber film. Light reflection and light scattering cause the low transmittance of the fiber film material, making it difficult to be transparent.

The fiber film in the prior art is a fiber film with a disordered structure in which fibers are randomly distributed, the light path is very complex and tortuous, the surface reflection and internal scattering are very serious, the light loss is huge, and the light transmittance is poor.

The design concept of the present invention is to allow light to pass through the intermediate orientation structure region as much as possible. This part of the fiber has less content and is relatively thin, and the orientation structure will reduce the interface reflection, thereby reducing the light loss. In this structure designed by the present invention, the thickness of the fiber membrane is mainly reflected by the fibers accumulated on the frame. The fiber content on the frame is high and the thickness is large, but the area ratio of the frame part is relatively small compared to the fiber membrane. Light loss is further controlled. Therefore, the fiber film of the present invention is more light-transmitting.

beneficial effect

The method of the invention is simple, and the finally prepared transparent fiber film has adjustable pore structure and porosity compared with solid traditional transparent film materials (glass, PET board, etc.) and fiber-reinforced transparent composite materials, and can keep fibers Morphological structure, with excellent air permeability and filtration performance.

Description of drawings

Fig. 1 is the preparation flow chart of the transparent fiber film of the present invention;

Fig. 2 is the structural schematic diagram of the basic unit 1 that constitutes a plane mesh structure of the present invention;

Fig. 3 is the overall structure schematic diagram of the special receiving base material of the present invention;

4 is a schematic structural diagram of a basic unit II constituting a planar structure according to the present invention;

Figure 5 shows the electric field simulation of substrates with different structures and the electron microscope images of the corresponding fiber membranes formed. Among them, the left image in the upper row is the electric field simulation of a rectangular substrate, the middle image is an electric field simulation of a regular hexagonal substrate, and the right image is this The electric field simulation of the substrate of the invention, the left picture in the next row is the electron microscope image of the fiber membrane formed by the rectangular substrate, the middle picture is the electron microscope image of the fiber membrane formed by the regular hexagonal substrate, and the right picture is the electron microscope of the fiber membrane formed by the substrate of the present invention picture;

6 is a schematic diagram of the formation mechanism of the orientation structure in the present invention;

FIG. 7 is an optical photograph of five fiber films with different light transmittances of the present invention, wherein T represents light transmittance.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

The specific source of the high molecular polymer used in the present invention or its structural parameters are as follows:

Example 1

A preparation method of a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (polyurethane) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The side length of the regular hexagon is 1mm; the thickness of the regular hexagon support and the inline support are both 100 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of spinning solution was 8wt%, the perfusion speed was 0.3ml/h, the spinning voltage was 25kV, the drum speed was 40rpm, the receiving distance was 10cm, the temperature was 25±2°C, and the relative humidity was 35%.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 1 μm, and the average thickness of the fiber film in the third part is 0.2 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 85%; the projected area of the fibers in the third part is 60% of the projected area of the basic unit II; the average diameter of the nanofibers is 200nm; the light transmittance of the transparent nanofiber film is 84% (the photo is shown in the left second image of Figure 7), the porosity is 80%, and the tensile strength is 30MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, and the upper and lower layers are both composed of a transparent tulle net with a light transmittance of 96%, and the thickness of the transparent tulle net is 50 μm;

The light transmittance of the transparent mask is 75%, and in the PM _0.3 filtration performance test, the filtration efficiency is 91% and the piezoresistance is 50Pa.

Comparative Example 1

A preparation method of a fiber membrane, basically the same as Example 1, the difference is only a special receiving base material, and the basic unit I constituting a plane network structure in the special receiving base material of Comparative Example 1 is only composed of a regular hexagon. The structure of the bracket (as shown in the middle diagram in the upper row of FIG. 5 ), the size of the regular hexagonal bracket is the same as that of the first embodiment.

The average thickness of the final nanofiber film is 1 μm; the average diameter of the nanofibers is 200 nm; the light transmittance of the nanofiber film is 50%, the porosity is 70%, and the tensile strength is 20MPa.

Comparing Example 1 with Comparative Example 1, it can be seen that the nanofiber membrane of Example 1 has higher light transmittance, higher porosity, and higher tensile strength. , the light mainly passes through the middle orientation structure area, this part of the fiber content is small and relatively thin, the orientation structure will reduce the interface reflection, so that the light loss is less; and the fiber film prepared in Comparative Example 1 is a disordered structure fiber film with randomly distributed fibers , the light path is very complex and tortuous, the surface reflection and internal scattering are very serious, the light loss is huge, and the light transmittance is poor.

Example 2

A preparation method of a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (polyacrylonitrile) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The length of the side of the regular hexagon is 1.5mm; the thickness of the regular hexagon support and the in-line support are both 150 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of spinning solution was 9wt%, the perfusion speed was 0.5ml/h, the spinning voltage was 15kV, the drum speed was 50rpm, the receiving distance was 15cm, the temperature was 25±2°C, and the relative humidity was 40%.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 5 μm, and the average thickness of the fiber film in the third part is 1 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 90%; the projected area of the fibers in the third part is basically 62% of the projected area of unit II; the average diameter of the nanofibers is 200 nm; the light transmittance of the transparent nanofiber membrane is 90% (the photo is shown in the left panel of Fig. 7), the porosity is 85%, and the tensile strength is 25MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, and the upper and lower layers are both composed of a transparent tulle mesh with a light transmittance of 97%, and the thickness of the transparent tulle mesh is 150 μm;

The light transmittance of the transparent mask is 82%, and in the PM _0.3 filtration performance test, the filtration efficiency is 92%, and the piezoresistance is 30Pa.

Example 3

A preparation method of a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (polyvinylidene fluoride) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The length of the side of the regular hexagon is 2mm; the thickness of the regular hexagon support and the in-line support are both 150 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of the spinning solution was 10 wt%, the perfusion speed was 1 ml/h, the spinning voltage was 15 kV, the drum speed was 60 rpm, the receiving distance was 15 cm, the temperature was 25 ± 2 °C, and the relative humidity was 45 %.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 10 μm, and the average thickness of the fiber film in the third part is 2 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 88%; the projected area of the fibers in the third part is the basic 64% of the projected area of unit II; the average diameter of the nanofibers is 200 nm; the light transmittance of the transparent nanofiber membrane is 80% (the photo is shown in the left third panel of Fig. 7), the porosity is 88%, and the tensile strength is 26MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, and the upper and lower layers are both composed of a transparent tulle net with a light transmittance of 96%, and the thickness of the transparent tulle net is 100 μm;

The light transmittance of the transparent mask is 65%, and in the PM _0.3 filtration performance test, the filtration efficiency is 95%, and the piezoresistance is 40Pa.

Example 4

A preparation method of a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (cellulose acetate) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The side length of the regular hexagon is 2.5mm; the thickness of the regular hexagon support and the inline support are both 200 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of spinning solution was 11 wt%, the perfusion speed was 1 ml/h, the spinning voltage was 20 kV, the drum speed was 50 rpm, the receiving distance was 20 cm, the temperature was 25 ± 2 °C, and the relative humidity was 40 %.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 15 μm, and the average thickness of the fiber film in the third part is 3 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 85%; the projected area of the fibers in the third part is the basic 63% of the projected area of unit II; the average diameter of the nanofibers is 200 nm; the light transmittance of the transparent nanofiber membrane is 78% (the photo is shown in the left fourth panel of Fig. 7), the porosity is 90%, and the tensile strength is 27MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, and the upper and lower layers are both composed of a transparent tulle mesh with a light transmittance of 97%, and the thickness of the transparent tulle mesh is 150 μm;

The light transmittance of the transparent mask is 55%, and in the PM _0.3 filtration performance test, the filtration efficiency is 98%, and the piezoresistance is 60Pa.

Example 5

A method for preparing a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (polymethyl methacrylate) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The length of the side of the regular hexagon is 1.5mm; the thickness of the regular hexagon support and the in-line support are both 150 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of spinning solution was 9wt%, the perfusion speed was 1ml/h, the spinning voltage was 10kV, the drum speed was 50rpm, the receiving distance was 15cm, the temperature was 25±2°C, and the relative humidity was 40 %.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 20 μm, and the average thickness of the fiber film in the third part is 4 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 82%; the projected area of the fibers in the third part is the basic 65% of the projected area of cell II; the average diameter of the nanofibers is 200 nm; the light transmittance of the transparent nanofiber film is 50%, the porosity is 91%, and the tensile strength is 28 MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, the upper and lower layers are both composed of transparent tulle nets with a light transmittance of 96%, and the thickness of the transparent tulle nets is 200 μm;

The light transmittance of the transparent mask is 45%, and in the PM _0.3 filtration performance test, the filtration efficiency is 99%, and the piezoresistance is 70Pa.

Example 6

A method for preparing a transparent nanofiber film, which adopts an electrospinning process and a special receiving base material to make a high molecular polymer (polyamide) into a transparent nanofiber film;

The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The side length of the regular hexagon is 1.5mm; the thickness of the regular hexagon support and the in-line support are both 200 μm;

The special receiving substrate is wrapped on the peripheral surface of the drum, and the drum is grounded;

The parameters of electrospinning were: the concentration of spinning solution was 9wt%, the perfusion speed was 0.5ml/h, the spinning voltage was 20kV, the drum speed was 60rpm, the receiving distance was 15cm, the temperature was 25±2°C, and the relative humidity was 45%.

The finally obtained transparent nanofiber film has a planar structure as a whole, and the basic unit II constituting the planar structure is a regular hexagonal structure formed by nanofibers in a special arrangement, and the special arrangement refers to: the basic unit II in the basic unit II. The fiber is divided into three parts, the fiber at the edge of the regular hexagon is recorded as the first part, and the fiber on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon is recorded as the first part. is the second part, and the fibers in the remaining positions are recorded as the third part;

The fibers of the first part are oriented in the orientation direction of A, and A is the direction parallel to each side of the regular hexagon in the regular hexagonal structure. The fibers of the second part are oriented in the orientation direction of B, and B are parallel to each other. in the direction of each connection;

The average thickness of the transparent nanofiber film is 5 μm, and the average thickness of the fiber film in the third part is 1 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is 95%; the projected area of the fibers in the third part is basically 70% of the projected area of unit II; the average diameter of the nanofibers is 200 nm; the light transmittance of the transparent nanofiber membrane is 96%, the porosity is 92%, and the tensile strength is 29 MPa.

The finally obtained transparent nanofiber film is used for the middle layer of the transparent mask, the transparent mask has a three-layer structure, and the upper and lower layers are both composed of a transparent tulle net with a light transmittance of 96%, and the thickness of the transparent tulle net is 100 μm;

The light transmittance of the transparent mask is 90%, and in the PM _0.3 filtration performance test, the filtration efficiency is 98%, and the piezoresistance is 10Pa.

Claims (9)

1. a preparation method of a transparent nanofiber membrane, is characterized in that: adopt electrospinning technique and special receiving base material to make high molecular polymer into transparent nanofiber membrane; The special receiving substrate refers to an insulating substrate with a planar mesh structure as a whole, and the basic unit I constituting the planar mesh structure is a planar structure connected by a regular hexagonal bracket and three inline brackets, and three One end of each in-line bracket meets at the center of the regular hexagonal support, and the other ends are respectively connected with three vertices of the regular hexagonal support, the three vertices being the non-adjacent vertices on the regular hexagonal support ; The side length of the regular hexagon is 1.0-2.5mm; the thickness of the regular hexagon support and the in-line support are both 100-200 μm; A special receiving substrate is wrapped around the perimeter of the drum, which is grounded. 2. the preparation method of a kind of transparent nanofiber film according to claim 1, is characterized in that, high molecular polymer is polyurethane, polyacrylonitrile, polyvinylidene fluoride, cellulose acetate, polymethyl methacrylate, One or more of polyamide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral, polyethylene oxide, chitosan and chitin. 3. The method for preparing a transparent nanofiber membrane according to claim 1, wherein the parameters of electrospinning are: the concentration of the spinning solution is 8-11wt%, and the perfusion speed is 0.3-1.0ml/h , the spinning voltage is 10-25kV, the rotating speed of the drum is 40-60rpm, the receiving distance is 10-20cm, the temperature is 25±2°C, and the relative humidity is 35-45%. 4. The transparent nanofiber film obtained by the method for preparing a transparent nanofiber film according to any one of claims 1 to 3, wherein the transparent nanofiber film has a planar structure as a whole, and the Basic unit II is a regular hexagonal structure formed by nanofibers in a special arrangement. The special arrangement means: the fibers in basic unit II are divided into three parts, and the fibers at the edge of the regular hexagonal structure are recorded as For the first part, the fibers on the three connecting lines between the center of the regular hexagon and the three non-adjacent vertices of the regular hexagon are recorded as the second part, and the fibers in the remaining positions are recorded as the third part; The average thickness of the transparent nanofiber film is 1-20 μm, and the average thickness of the fiber film in the third part is 0.2-4 μm; the fibers in the third part are arranged in a certain orientation, and the degree of orientation is greater than 80%; The projected area of the fibers of the third portion is 60% or more of the projected area of the basic unit II. 5. The transparent nanofiber film according to claim 4, wherein the fibers of the first part are aligned in an orientation direction of A, and A is a direction parallel to each side of the regular hexagon in the regular hexagon structure, respectively, The fibers of the second part are oriented in an orientation direction B, and B is a direction parallel to each connecting line respectively. 6 . The transparent nanofiber film according to claim 4 , wherein the average diameter of the nanofibers is 200 nm. 7 . 7 . The transparent nanofiber film according to claim 4 , wherein the transparent nanofiber film has a light transmittance of 50-96%, a porosity of 80-92%, and a tensile strength of 25-30 MPa. 8 . 8. the application of the transparent nanofiber membrane as claimed in any one of claims 4 to 7 on the transparent mask, it is characterized in that: the transparent mask is a three-layer structure, and the middle layer is made up of the transparent nanofiber membrane, and the upper and lower The layers are all composed of transparent tulle nets with a light transmittance of more than 96%, and the thickness of the transparent tulle nets is 50-200 μm. 9. The application according to claim 8, wherein the light transmittance of the transparent mask is greater than 45%, and during the PM _0.3 filtration performance test, the filtration efficiency is greater than 90%, and the piezoresistance is less than 100Pa.

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