CN113509800B - Multi-scale structure plant fiber air filtering material and preparation method and application thereof - Google Patents

Abstract

The invention provides a plant fiber air filtering material with a multi-scale structure and a preparation method and application thereof. The multi-scale structure plant fiber air filter material is formed by overlapping plant fibers with different diameters. The inner part mainly comprises a three-layer structure which is a micron-scale plant fiber layer, a submicron-scale plant fiber layer and a nano-scale plant fiber layer from outside to inside, and the three-layer structure respectively contains a large amount of large-scale pores of 1-10 microns, medium-scale pores of 0.1-1 micron and small-scale pores of 1-100 nanometers, so that a gradient pore structure is formed, and the three-layer structure has good filtering and intercepting capabilities for particles, bacteria and the like with different scales in gas. The plant fiber air filtering material with the multi-scale structure has high specific surface and good air permeability, can effectively prevent invasion of harmful substances such as micron-sized dust in air, and has wide application prospects in the fields of air purification, medical air-permeable protection barrier materials and the like.

Description

A kind of multi-scale structure plant fiber air filter material and its preparation method and use

technical field

The invention relates to the field of nanotechnology, in particular to a multi-scale structure plant fiber air filter material and a preparation method and application thereof.

Background technique

The air in which people live is full of all kinds of micro-nano particles, which are not only easy to be inhaled by people and cause direct harm, but also a major transmission medium for many bacteria and viruses to cause diseases. Therefore, in order to improve air quality and prevent the harm of air pollutants, various types of air purification filter materials are essential.

In current commercial air protection, meltblown cloth base materials are widely used due to their high processability. However, as a petroleum-based plastic, it comes from non-renewable resources, and the processing process is complicated. Improper disposal after use can easily cause environmental plastic pollution. In addition, most of the currently used melt-blown cloth-based materials have a single-scale structure, and it is necessary to ensure that the pores between the internal fibers are small enough to achieve the filtering effect, but a long time will cause the pores of this structure to be blocked by harmful substances. The filtering effect is reduced.

Therefore, how to develop a new type of green and environmentally friendly multi-scale air filter material is an urgent problem to be solved by those skilled in the field of air purification.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-scale structure plant fiber air filter material. It has dense weak interactions and thus constitutes a dense three-dimensional network structure.

To this end, the present application provides the following aspects.

<1>, a multi-scale plant fiber air filter material, which has a three-dimensional network structure formed by the intertwining and overlapping of multi-scale plant fibers, wherein the multi-scale plant fibers at least include a diameter of 1-100 nanometers. Nano-scale plant fibers, sub-micron plant fibers with a diameter of 0.1-1 micron, and micron-scale plant fibers with a diameter of 1-50 microns,

The multi-scale structure plant fiber air filter material at least sequentially includes a micron-scale plant fiber layer formed by the micron-scale plant fibers as an outer layer, and the sub-micron-scale plant fibers formed by the sub-micron-scale plant fibers. layer as the middle layer and the nano-scale plant fiber layer formed by the nano-scale plant fiber as the inner layer, and wherein the main pores of the outer layer, the middle layer and the inner layer in the multi-scale plant fiber air filter material are respectively Large-scale pores of 1-10 microns, medium-scale pores of 0.1-1 micron, and small-scale pores of 1-100 nanometers make the pore gradient inside the material gradually decrease from the outside to the inside, so that large pores can filter large particles. Gradient filtration effect of small pore filtration adsorption of small particles.

<2>, according to the multi-scale structure plant fiber air filter material described above, wherein, the nanoscale plant nanofibers with a diameter of 1-100 nanometers account for the mass percentage of the overall multi-scale structure plant fiber air filter material: Not less than 5% and not higher than 30%.

<3>. The multi-scale structure plant fiber air filter material according to the foregoing, wherein, the submicron plant nanofibers with a diameter of 0.1-1 micron account for the mass percentage of the overall multi-scale structure plant fiber air filter material is not less than 10% and not more than 50%.

<4>, according to the multi-scale structure plant fiber air filter material described above, wherein, the micron-scale plant nanofibers with a diameter of 1-50 microns account for the overall mass percentage of the multi-scale structure plant fiber air filter material: not higher than 85%.

<5>. According to the multi-scale structure plant fiber air filter material described above, wherein, the micron-scale plant fiber layer is formed by brushing and drying naturally so that dense hydrogen bonds are formed between the micron-scale plant fibers inside it. A large number of large-scale pores of 1-10 microns are formed by overlapping with each other.

<6>. According to the multi-scale structure plant fiber air filter material described above, wherein, the sub-micron-scale plant fiber layer is formed by brushing and freeze-drying, and the sub-micron-scale plant fibers inside are formed with dense The hydrogen bonds overlap each other to form a large number of mesoscale pores with a scale of 0.1-1 μm.

<7>. According to the multi-scale structure plant fiber air filter material described above, wherein, the nanoscale plant fiber layer is formed by spray drying, and the nanoscale plant fibers inside the nanoscale plant fiber overlap each other with dense hydrogen bonds. A large number of small-scale pores with a scale of 1-100 nanometers are then formed.

<8>. The multi-scale structure plant fiber air filter material according to the foregoing, wherein the multi-scale structure plant fiber air filter material is a membrane material.

<9>, a method for preparing the multi-scale structure plant fiber air filter material described in any one of the foregoing, the method comprises:

A) preparing nano-scale plant fibers, sub-micron plant fibers, and micron-scale plant fibers into an aqueous dispersion solution with a mass fraction of 0.1%-20%;

B) brushing the micron-scale plant fiber aqueous dispersion on the substrate, repeatedly brushing 1-10 times, and then letting it dry naturally for 24 hours;

C) the submicron-scale plant fiber aqueous dispersion is brushed on the top of the naturally dried micron-scale plant fiber layer, after repeated brushing 1-10 times, it is frozen and then placed in a freeze dryer for freeze-drying;

D) uniformly spraying the nanoscale fiber aqueous dispersion on the submicron plant fiber layer;

E) After it is dried by baking, natural drying, freeze-drying, etc., it is removed from the substrate to obtain a multi-scale structure plant fiber air filter material.

<10>, the multi-scale structure plant fiber air filter material according to any one of <1>-<8> in the preparation of protective masks, air purifiers, fresh air system filters, smart screens, medical protective clothing, etc. use.

<11>. The multi-scale structure plant fiber air filter material according to any one of <1>-<8> has at least one of the following properties:

i) The multi-scale structure plant fiber air filter material has good air permeability, and when the flow rate is 5L/min, the back pressure is not higher than 25Pa/cm ² ; and

ii) The multi-scale structure plant fiber air filter material has a good air protection effect, and has a good barrier ability to PM _2.5 in the gas, and the filtration barrier efficiency is higher than 90% at a flow rate of 10L/min.

Description of drawings

FIG. 1 is a digital photo of the multi-scale structure birch fiber air filter material membrane prepared in Example 1 of the present invention.

2 is a scanning electron microscope photograph of the multi-scale structure birch fiber air filter material membrane prepared in Example 1 of the present invention. It can be seen that the fibers are tightly wound together to form a dense three-dimensional network structure. In addition, this scan also shows that different layers of birch air filter material membrane with multi-scale structure have different pore structures, from the inside to the outside, they are small-scale pores with a scale of 1-100 nanometers, and medium-scale pores with a scale of 0.1-1 μm. and large-scale pores of 1-10 microns.

Figure 3 shows the flow-back pressure curve of the multi-scale structure birch fiber air filter membrane. It can be seen that this multi-scale structure birch fiber air filter membrane has good air permeability. When the flow rate is 5L/min, the back pressure Not higher than 24Pa/cm ² .

Figure 4 is the flow rate-filtration efficiency curve of the multi-scale structure birch fiber air filtration membrane, from which it can be seen that this multi-scale structure birch fiber air filtration membrane has a good air protection effect and has a good effect on PM _2.5 in the gas. Barrier capacity, when the flow rate is 10L/min, the filtration barrier efficiency is higher than 91%.

5 is a digital photo of the multi-scale structure birch fiber air filter mask prepared by application implementation 1 of the present invention.

FIG. 6 is a digital photo of the multi-scale structure birch fiber protective surgical gown prepared by application implementation 1 of the present invention.

Detailed ways

1) Multi-scale plant fiber air filter material

The first aspect of the present application is to provide a multi-scale plant fiber air filter material, the multi-scale structure plant fiber air filter material is formed by the interaction of abundant hydroxyl groups on the surface of the fiber to form hydrogen bonds so that a variety of different diameters, Plant fibers of different lengths are tightly wound and overlapped with each other. An example of such a tightly wound lap is shown in FIG. 2 . This binding promotes the formation of a dense network of plant fibers. The plant fibers of various scales include, but are not limited to, plant nanofibers with a diameter of 1-100 nanometers, plant submicron fibers with a diameter of 0.1-1 micrometer, and plant microfibers with a diameter of 1-50 micrometers. Preferably, relative to the multi-scale structure plant fiber air filter material, the mass percentage of nanocellulose with a diameter of less than 100 nanometers is not less than 5%, not higher than 30% (ie, 5-30 mass%, more preferably 10% by mass). -20 mass%), the mass percentage of the micron fibers with a diameter of 0.1-1 micron is not less than 10%, not more than 50% (ie, 10-50 mass%, more preferably 20-30 mass%), and the The mass percentage of the micron-scale plant nanofibers with a diameter of 1-50 microns is not higher than 85% (more preferably 50-60%).

Preferably, the diameter of the plant nanofibers is in the range of 20-1000 nanometers, more preferably in the range of 500-1000 nanometers.

Preferably, the diameter of the plant submicron fibers is in the range of 1-50 microns, more preferably in the range of 5-20.

Preferably, the diameter of the plant microfibers is in the range of 10-500 microns, more preferably in the range of 100-300.

This decreases in fiber size from top to bottom (ie, from the basal side, the layer closest to the substrate is the lowermost layer, also called the inner layer, and the layer farthest from the substrate is the uppermost layer, also called the outer layer) Three layers of plant fiber, which respectively have a large number of large-scale pores of 1-10 microns, a large number of meso-scale pores of 0.1-1 micron scale, and a large number of small-scale pores of 1-100 nanometers, thus forming multi-scale plants Gradient distribution of pores within a fibrous air filter material. Air filtration is carried out with the side with the larger pores facing outward, which can achieve the gradient filtration effect of filtering large particles with large pores and filtering and adsorbing small particles with small pores. Effect. In addition to the above three most basic layers, the multi-scale plant fiber air filter material of the present invention can also obtain other corresponding layers by other means such as brushing, spraying, etc., for obtaining other properties.

Preferably, the diameter of the large-scale pores is in the range of 10-100 microns, more preferably in the range of 20-50 microns.

Preferably, the diameter of the mesoscale pores is in the range of 0.1-10 microns, more preferably in the range of 0.5-5 microns.

Preferably, the diameter of the small-scale pores is in the range of 1-100 nanometers, more preferably in the range of 5-50 nanometers.

The macroscopic form of this multi-scale structure plant fiber air filter material is a membrane material.

Thus, the multi-scale structure plant fiber air filter material has at least one of the following properties:

i) The multi-scale structure plant fiber air filter material has good air permeability, and when the flow rate is 5L/min, the back pressure is not higher than 25Pa/cm ² ;

ii) The multi-scale structure plant fiber air filter material has better air protection effect,

PM _2.5 has good blocking ability, and the filtration blocking efficiency is higher than 90% at the flow rate of 10L/min.

The term "plant fiber" refers to nanoscale and microscale fibers derived from natural plants, including but not limited to at least one of wood, leaves, straw, hay, hemp, bamboo, bagasse, rice husks of natural plants.

The term "weak interaction" as used herein refers to hydrogen bonding interactions resulting from electrostatic interactions between highly electronegative atoms and hydrogen atoms.

The term "back pressure" refers to the pressure that the fluid discharged from the system receives at the outlet in the opposite direction of flow.

The term "bulk pores" refers to pores that account for at least 60% or more, preferably 70% or more, and more preferably 90% or more.

2) The preparation method of the multi-scale structure plant fiber air filter material of the present invention

A second aspect of the present disclosure provides a method for preparing a multi-scale structure plant fiber air filter material, comprising the following steps:

A) Prepare nano-scale plant fibers, sub-micron plant fibers, and micron-scale plant fibers into an aqueous dispersion solution with a mass fraction of 0.1%-20%:

B) Brush the micron-scale plant fiber aqueous dispersion on the substrate, repeat the brushing 1-10 times, and then let it dry naturally for 24 hours, wherein the substrate can support the micron-scale plant fibers as long as there is no contact with the plant fibers. It is sufficient to form a strong interaction force (which is conducive to the peeling of the finally formed filter material), for example, a specific example thereof can be a metal substrate, or a polymer filter cloth with a pore size below 100 nanometers;

C) the submicron-scale plant fiber aqueous dispersion is brushed on the top of the naturally dried micron-scale plant fiber layer, after repeated brushing 1-10 times, it is frozen and then placed in a freeze dryer for freeze-drying;

D) uniformly spraying the nanoscale fiber aqueous dispersion on the submicron plant fiber layer;

E) After drying it, for example, by baking, natural drying, freeze-drying, etc., it is removed from the substrate, and the multi-scale structure plant fiber air filter material.

The term "brushing" refers to the operation of manually dipping a brush into the finishing slurry for brushing.

The term "freeze-drying" means that in the multi-scale structure plant fiber air filter material preparation method of the present application, the molding process is freeze-drying molding. A specific embodiment thereof is: placing the material coated with the submicron plant fiber aqueous dispersion in a low temperature below -5°C, making the aqueous dispersion freeze into ice, and then placing it in a vacuum below 500Pa and a temperature below 500Pa. For freeze-drying molding in a vacuum environment of 10-80 °C. Another more specific embodiment is: the material coated with the submicron plant fiber aqueous dispersion is placed in liquid nitrogen under normal pressure, the aqueous dispersion is frozen into ice, and then placed in a vacuum of 500Pa. The following freeze-drying molding is performed in a vacuum environment at a temperature of 10-80°C.

The term "baking" refers to the process of volatilizing and dehydrating the water in the form of dry heat under the ignition point of the material by baking and baking. For the baking in the preparation process of the multi-scale structure plant fiber air filter material, the drying temperature should not exceed 80 °C, so as to avoid the material deformation caused by the rapid evaporation of water, and the heating rate should not exceed 10 °C/min, to prevent the temperature difference between the front and rear during the baking process. If it is too large, the deformation of the material caused by the change of the water volatilization rate is large.

The term "spraying" refers to a coating method that is dispersed into uniform and fine droplets by means of a spray gun or a disc atomizer by means of pressure or centrifugal force, and is applied to the surface of the object to be coated.

In the preparation method of the multi-scale structure plant fiber air filter material of the present disclosure, the size of the plant fiber affects the size of the pores accordingly. At the same time, different processes also have corresponding effects on the size of the pores. The brushing process of large-scale and medium-scale plant fibers is conducive to the formation of large-scale pores during the drying process because a large number of water molecules are filled between the plant fibers. The spraying process of small-scale plant fibers exists in the form of sprayed water droplets, resulting in a larger specific surface, which can quickly dry and volatilize water in the air, so that the water content is less when it falls on the substrate, which is conducive to drying. Small-scale pores are formed during the process. As for the specific drying method of each plant fiber layer, it is to better protect the pores inside the plant fiber layer and prevent them from being damaged. The large-scale micro-pore structure is stable and not easily damaged, and a time-saving and labor-saving natural drying method can be used. If the mesoscale submicron pores are naturally dried, the structure will collapse due to the surface tension generated by the volatilization of water during the drying process, so they can be completely preserved by freeze-drying. As for small-scale nanopores, because nano-scale plant fibers themselves have a specific surface and surface hydrogen bonds far exceeding those of micro-scale plant fibers and sub-micron-scale plant fibers, they have extremely dense weak interactions with each other, and they can The nanoscale pore structure is maintained, so a variety of drying methods can be used.

3) Advantages and applications of the multi-scale structure plant fiber air filter material of the present invention

The multi-scale structure plant fiber air filter material of the present invention has many significant differences compared with the melt-blown cloth base material widely used in the market at present. For example, A) currently widely used melt-blown cloth-based materials on the market are directly or indirectly derived from non-renewable petroleum, while the multi-scale structure plant fiber air filter material of the present invention is a full biomass raw material, which is green and degradable; B) The multi-scale structure plant fiber air filter material of the present invention is more durable and has better effect. Most of the melt-blown cloth base materials widely used in the market currently have a single-scale structure, which causes them to be easily affected by micro-nano dust and the like during use. Harmful particles block pores, so that the filtering effect decreases rapidly, and the multi-scale structure plant fiber air filter material of the present invention adopts a multi-scale classification filtering mechanism, which is not easy to be blocked by harmful particles such as micro-nano dust, and can still be used for a long time. Effect; C) the multi-scale structure plant fiber air filter material of the present invention is relatively simpler and consumes less energy than the meltblown cloth-based material widely used in the market; D) The multi-scale structure plant fiber air filter material of the present invention is Degradable material, the melt-blown cloth-based material widely used in the market at present, its main component is petroleum-based polymer, and improper disposal has serious environmental risks. The multi-scale structure plant fiber air filter material of the present invention is a whole biomass structure, Compostable and naturally degradable.

The multi-scale structure plant fiber air filter material of the invention can effectively prevent the invasion of harmful substances such as bacteria and virus micro-nano dust, has good air permeability, and has wide application prospects, and can be used in the preparation of protective masks, air purifiers, and fresh air system filtration. It has been applied in various air purification fields such as air conditioners, smart screens, and medical protective clothing.

In order to further understand the present invention, the multi-scale structure plant fiber air filter material provided by the present invention will be described in detail below with reference to the examples. It should be understood that the specific embodiments described herein are only for explaining the present invention, but not for limiting the present invention.

Example

Example 1

A) The birch plant nanofibers with a diameter of 1-100 nanometers, the birch plant nanofibers with a diameter of 0.1-1 micrometers, and the birch plant microfibers with a diameter of 1-50 micrometers were formulated into mass fractions of 0.5% and 5%, respectively, 15% of 2L water slurry;

B) mechanically stirring the prepared slurry, specifically a German IKARW20 agitator, with a rotating speed of 500 revolutions per minute, and a stirring time of 2 hours;

C) brush the micron-scale plant fiber aqueous dispersion on the aluminum foil paper substrate, repeat the brushing 4 times, and then let it dry naturally for 24 hours;

D) The submicron-level plant fiber aqueous dispersion is brushed on the naturally dried micron-level plant fiber layer, and after repeated brushing 6 times, it is frozen and placed in a freeze dryer, and the vacuum degree is 20Pa, and the temperature is 20 Freeze drying in ℃ environment:

E) uniformly spraying 3 layers of nano-scale fiber aqueous dispersion on the sub-micron-scale plant fiber layer;

F) Carefully peel off this wet film from the filter cloth, then quickly and evenly apply it on the baking ridge, slowly heat up to 60 degrees Celsius at a heating rate of 5 degrees Celsius per minute and keep warm for 1 hour to obtain a multi-scale Structural plant fiber air filtration membrane.

Fig. 1 is the digital photograph of the multi-scale structure birch fiber air filter material film prepared in Example 1 of the present invention;

2 is a scanning electron microscope photograph of the multi-scale structure birch fiber air filter material membrane prepared in Example 1 of the present invention. It can be seen that the fibers of three scales are tightly entangled together to form a three-dimensional network structure. In addition, this scan also shows that the multi-scale structure birch air filter material membrane has a variety of pore structures, which are small-scale pores on the scale of 1-100 nanometers, meso-scale pores on the scale of 0.1-1 μm and pores on the scale of 1-10 μm. large-scale pores;

Figure 3 shows the flow-back pressure curve of the multi-scale structure birch fiber air filter membrane. It can be seen that this multi-scale structure birch fiber air filter membrane has good air permeability. When the flow rate is 5L/min, the back pressure Not higher than 24Pa/cm ² ;

Figure 4 is the flow rate-filtration efficiency curve of the multi-scale structure birch fiber air filtration membrane, from which it can be seen that this multi-scale structure birch fiber air filtration membrane has a good air protection effect and has a good effect on PM _2.5 in the gas. Barrier capacity, when the flow rate is 10L/min, the filtration barrier efficiency is higher than 91%.

Comparative Example 1

A) The birch plant nanofibers with a diameter of 1-100 nanometers are respectively formulated into 2L water slurries with mass fractions of 0.5%, 5% and 15%;

B) mechanically stirring the prepared slurry, specifically a German IKARW20 agitator, with a rotating speed of 500 revolutions per minute, and a stirring time of 2 hours;

C) brush 15% of the nanoscale plant fiber aqueous dispersion on the aluminum foil paper substrate, repeat the brushing 4 times, and then let it dry naturally for 24 hours;

D) Brush 5% of the nano-scale plant fiber aqueous dispersion on the naturally dried micron-scale plant fiber layer, and after repeated brushing 6 times, freeze it and place it in a freeze dryer at a vacuum degree of 20Pa and a temperature of 20Pa. Freeze-dried at 20°C;

E) uniformly spray 3 layers of 0.5% nanoscale fiber aqueous dispersion on the submicron plant fiber layer;

F) This wet film is carefully peeled off from the filter cloth, and then quickly and evenly applied on the baking ridge, slowly warming up to 60 degrees Celsius at a heating rate of 5 degrees Celsius per minute and then keeping warm for 1 hour to obtain nanostructures Plant fiber air filtration membrane.

The inside of this comparative example is mainly small-scale pores with a scale of 1-100 nanometers, and the air permeability is poor. When the flow rate is 5 L/min, the back pressure is higher than 50Pa/cm ² , which has a good barrier ability to PM _2.5 in the gas. , at a flow rate of 10 L/min, the filtration barrier efficiency is 95%.

Comparative Example 2

A) The birch plant nanofibers with a diameter of 0.1-1 micron were prepared into 2L aqueous slurries with mass fractions of 0.5%, 5% and 15%;

B) mechanically stirring the prepared slurry, specifically a German IKARW20 agitator, with a rotating speed of 500 revolutions per minute, and a stirring time of 2 hours;

C) 15% sub-micron plant fiber aqueous dispersion is brushed on the aluminum foil paper substrate, brushed repeatedly 4 times, and then allowed to dry naturally for 24 hours;

D) 5% submicron-level plant fiber aqueous dispersion is brushed on the naturally dried micron-level plant fiber layer, after repeated brushing 6 times, it is frozen and placed in a freeze dryer at a vacuum degree of 20Pa, Freeze drying at 20°C;

E) uniformly spray 3 layers of 0.5% submicron fiber aqueous dispersion on the submicron plant fiber layer;

F) This wet film is carefully peeled off from the filter cloth, and then quickly and evenly applied on the baking ridge, slowly warming up to 60 degrees Celsius at a heating rate of 5 degrees Celsius per minute and then keeping warm for 1 hour to obtain nanostructures Plant fiber air filtration membrane.

In this comparative example, there are mainly mesoscale pores with a scale of 0.1-1 microns, and the air permeability is poor. When the flow rate is 5 L/min, the back pressure is 26Pa/cm ² , which has a certain barrier ability to PM _2.5 in the gas. The flow rate is 10L/min, and the filtration barrier efficiency is 65%.

Comparative Example 3

A) The birch plant nanofibers with a diameter of 1-50 microns are respectively formulated into 2L aqueous slurries with mass fractions of 0.5%, 5% and 15%;

B) mechanically stirring the prepared slurry, specifically a German IKARW20 agitator, with a rotating speed of 500 revolutions per minute, and a stirring time of 2 hours;

C) brush 15% micron-scale plant fiber aqueous dispersion on the aluminum foil paper substrate, repeat the brushing 4 times, and then let it dry naturally for 24 hours;

D) Brush 5% of the micron-scale plant fiber aqueous dispersion on the naturally-dried micron-scale plant fiber layer, after repeated brushing 6 times, freeze it and place it in a freeze dryer at a vacuum degree of 20Pa and a temperature of 20Pa. Freeze-dried at 20°C;

E) uniformly spray 3 layers of 0.5% micron-scale fiber aqueous dispersion on the sub-micron-scale plant fiber layer;

F) This wet film is carefully peeled off from the filter cloth, and then quickly and evenly applied on the baking ridge, slowly warming up to 60 degrees Celsius at a heating rate of 5 degrees Celsius per minute and then keeping warm for 1 hour to obtain nanostructures Plant fiber air filtration membrane.

The inside of the comparative example is mainly large-scale pores of 1-10 microns, with good air permeability. When the flow rate is 5L/min, the back pressure is lower than 20Pa/cm ² , and the barrier ability to PM _2.5 in the gas is poor. is 10L/min, and the filtration blocking efficiency is 33%.

Application Example 1

A) The multi-scale structure birch fiber air filter material film obtained in Example 1 is used as an intermediate filter layer, and a layer of spunbond layer is lined inside and outside, and is fully ironed;

B) Through the mechanical processing of the mask machine, a multi-scale structure birch fiber air filter mask is obtained.

5 is a digital photo of the multi-scale structure birch fiber air filter mask prepared by application implementation 1 of the present invention.

The multi-scale structure birch fiber air filter mask prepared by the application of the present invention 1 has a filtration efficiency of 93% at a flow rate of 10L/min, and its filtration effect under the same flow rate after 3 days of use is 91%, indicating that the mask has excellent usability. .

Application Example 2

A) The multi-scale structure birch fiber air filter material film obtained in Example 1 is used as the intermediate filter layer, and a layer of spunbond layer is lined inside and outside, and is fully ironed;

B) Through corresponding machining, a multi-scale structure birch fiber protective surgical gown is obtained.

FIG. 6 is a digital photo of the multi-scale structure birch fiber protective surgical gown prepared by application implementation 1 of the present invention.

The above descriptions of the specific embodiments and embodiments are only used to help understand the method and the core idea of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle and spirit of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention Inside.

Claims (10)

1. A multi-scale structure plant fiber air filter material, it has a three-dimensional network structure formed by the intertwining and overlapping of various scale plant fibers, wherein the various scale plant fibers at least comprise a nanometer diameter of 1-100 nanometers. Grade plant fibers, sub-micron plant fibers with a diameter of 0.1-1 micron, and micron-scale plant fibers with a diameter of 1-50 microns, The multi-scale structure plant fiber air filter material at least sequentially includes a micron-scale plant fiber layer formed by the micron-scale plant fibers as an outer layer, and the sub-micron-scale plant fibers formed by the sub-micron-scale plant fibers. layer as the middle layer and the nano-scale plant fiber layer formed by the nano-scale plant fiber as the inner layer, and wherein the main pores of the outer layer, the middle layer and the inner layer of the multi-scale structure plant fiber air filter material are respectively through The large-scale pores of 1-10 microns are formed by overlapping hydrogen bonds between the micron-scale plant fibers, and the 0.1-1 micron pores are formed by overlapping the sub-micron plant fibers with dense hydrogen bonds. The micro-scale mesoscale pores and the 1-100 nanometer-scale small-scale pores formed by the hydrogen bonding between the nano-scale plant fibers make the internal pore gradient of the material gradually decrease from the outside to the inside, so as to achieve large-scale pores. Pore filtration absorbs large particles, and small pore filtration absorbs small particles. 2. The multi-scale structure plant fiber air filter material according to claim 1, wherein the mass percentage of the nanoscale plant nanofibers with a diameter of 1-100 nanometers in the overall multi-scale structure plant fiber air filter material is: Not less than 5% and not higher than 30%. 3. The multi-scale structure plant fiber air filter material according to claim 1, wherein, the submicron plant nanofibers with a diameter of 0.1-1 micron account for the mass percentage of the overall multi-scale structure plant fiber air filter material is not less than 10% and not higher than 50%. 4. The multi-scale structure plant fiber air filter material according to claim 1, wherein the mass percentage of the micron-scale plant nanofibers with a diameter of 1-50 microns in the overall multi-scale structure plant fiber air filter material is: not higher than 85%. 5 . The multi-scale structure plant fiber air filter material according to claim 1 , wherein the micron-scale plant fiber layer is formed by natural drying by brushing. 6 . 6 . The multi-scale structure plant fiber air filter material according to claim 1 , wherein the sub-micron plant fiber layer is formed by brush coating and freeze drying. 7 . 7. The multi-scale structure plant fiber air filter material according to claim 1, wherein the nano-scale plant fiber layer is formed by spray drying. 8. The multi-scale structure plant fiber air filter material according to claim 1, wherein the multi-scale structure plant fiber air filter material is a membrane material. 9. A method for preparing the multi-scale structure plant fiber air filter material according to any one of claims 1-8, the method comprising: A) preparing nanoscale plant fibers, submicron plant fibers, and micron plant fibers into an aqueous dispersion solution with a mass fraction of 0.1%-20%; B) brushing the micron-scale plant fiber aqueous dispersion on the substrate, repeatedly brushing 1-10 times, and then letting it dry naturally for 24 hours; C) the submicron-scale plant fiber aqueous dispersion is brushed on the dried micron-scale plant fiber layer, after repeated brushing 1-10 times, it is frozen and then placed in a freeze-drying machine for freeze-drying; D) uniformly spraying the nanoscale fiber aqueous dispersion on the submicron plant fiber layer; E) removing it from the substrate after drying to obtain the multi-scale structure plant fiber air filter material. 10. A use of the multi-scale structure plant fiber air filter material according to any one of claims 1-8 in the preparation of protective masks, air purifiers, fresh air system filters, smart screens and medical protective clothing.

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