CN113509800B - Multi-scale structure plant fiber air filtering material and preparation method and application thereof - Google Patents
Multi-scale structure plant fiber air filtering material and preparation method and application thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/0001—Making filtering elements
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- B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
- B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
- B01D39/1615—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of natural origin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/54—Particle separators, e.g. dust precipitators, using ultra-fine filter sheets or diaphragms
- B01D46/543—Particle separators, e.g. dust precipitators, using ultra-fine filter sheets or diaphragms using membranes
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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
Technical Field
The invention relates to the field of nanotechnology, in particular to a plant fiber air filtering material with a multi-scale structure and a preparation method and application thereof.
Background
The air in which people live is filled with various micro-nano particles, which are not only easy to be inhaled by people to cause direct injury, but also are a main transmission medium for diseases caused by a plurality of bacteria and viruses. Therefore, various air purification filter materials are necessary to improve the air quality and prevent the air pollution.
In current commercial air protection, meltblown based materials are widely used because of their strong processability. However, as a petroleum-based plastic, the petroleum-based plastic comes from non-renewable resources, the processing flow is complex, and the environmental plastic pollution is easily caused by improper disposal after use. In addition, most of the melt-blown fabric base materials used at present are single-scale structures, and the pores among the internal fibers must be ensured to be small enough to realize the filtering effect, but the pores of the structures are blocked by harmful substances after a long time, so that the filtering effect is reduced.
Therefore, how to develop a novel green environment-friendly multi-scale structure air filtering material is a problem to be solved urgently by technical personnel in the field of air purification.
Disclosure of Invention
The invention aims to provide a multi-scale structure plant fiber air filter material which is formed by overlapping a plurality of plant fibers with different diameters and different lengths, wherein dense weak interaction exists among various fibers, and a dense three-dimensional network structure is formed by the dense weak interaction.
To this end, the present application provides several aspects as follows.
<1> a multi-scale plant fiber air filter material, which has a three-dimensional network structure formed by winding and lapping a plurality of scale plant fibers, wherein the multi-scale plant fibers at least comprise nanoscale plant fibers with the diameter of 1-100 nanometers, submicron plant fibers with the diameter of 0.1-1 micrometer and micron plant fibers with the diameter of 1-50 micrometers,
the multi-scale structure plant fiber air filter material at least comprises a micron-scale plant fiber layer formed by micron-scale plant fibers as an outer layer from outside to inside in sequence, a submicron-scale plant fiber layer formed by the submicron-scale plant fibers as an intermediate layer and a nano-scale plant fiber layer formed by the nano-scale plant fibers as an inner layer, and the main pores of the outer layer, the intermediate layer and the inner layer in the multi-scale plant fiber air filter material are respectively a large-scale pore of 1-10 microns, a medium-scale pore of 0.1-1 microns and a small-scale pore of 1-100 nanometers, so that the internal pore gradient of the material is gradually reduced from the outside to the inside, and the gradient filtering effect of filtering large particles by large pores and filtering and absorbing small particles by small pores is realized.
<2> the air filter material of plant fiber with multi-scale structure, wherein the nano-scale plant nano-fiber with the diameter of 1-100 nm accounts for not less than 5% and not more than 30% of the whole air filter material of plant fiber with multi-scale structure by mass.
<3> the plant fiber air filtration material with a multi-scale structure as described above, wherein the submicron plant nanofiber with a diameter of 0.1-1 μm accounts for not less than 10% and not more than 50% of the whole plant fiber air filtration material with a multi-scale structure by mass.
<4> the air filter material of plant fiber with multi-scale structure, wherein the micron-sized plant nano-fiber with the diameter of 1-50 microns accounts for not more than 85% of the whole air filter material of plant fiber with multi-scale structure by mass.
<5> the air filter material of plant fiber with multi-scale structure, wherein the layer of plant fiber with micron scale is formed by coating and naturally drying so that the plant fiber with micron scale inside is overlapped with each other with dense hydrogen bonds to form a large amount of pores with large scale of 1-10 microns.
<6> the multi-scale structure plant fiber air filter material according to the above, wherein the sub-micron plant fiber layer is formed by brush coating and freeze drying, and a large number of medium-scale pores of 0.1 to 1 micron scale are formed by overlapping the sub-micron plant fibers inside the sub-micron plant fiber layer with each other through dense hydrogen bonds.
<7> the air filter material of plant fiber with multi-scale structure, wherein the nano-scale plant fiber layer is formed by spray drying, and the nano-scale plant fibers inside the nano-scale plant fiber layer are mutually overlapped by dense hydrogen bonds to form a large amount of small-scale pores with the size of 1-100 nanometers.
<8> the plant fiber air filter material of multi-scale structure as described above, wherein the plant fiber air filter material of multi-scale structure is a membrane material.
<9> a method for preparing the multi-scale structure plant fiber air filter material of any one of the above, the method comprising:
A) preparing the nano-scale plant fiber, the submicron-scale plant fiber and the micron-scale plant fiber into a water dispersion solution with the mass fraction of 0.1-20%;
B) brushing the micron-sized plant fiber aqueous dispersion on a substrate, repeatedly brushing for 1-10 times, and naturally drying for 24 hours;
C) brushing the submicron plant fiber aqueous dispersion on a naturally dried micron plant fiber layer, repeatedly brushing for 1-10 times, freezing, and freeze-drying in a freeze dryer;
D) uniformly spraying the nano-scale fiber aqueous dispersion on the submicron-scale plant fiber layer;
E) drying the air-filtering material by baking, naturally drying, freeze-drying and the like, and then taking down the air-filtering material from the substrate to obtain the plant fiber air-filtering material with the multi-scale structure.
<10 > and the application of the plant fiber air filtering material with the multi-scale structure according to any one of <1> to <8> in the aspects of preparing protective masks, air purifiers, fresh air system filters, intelligent screen windows, medical protective clothing and the like.
<11>, the multi-scale structure plant fiber air filter material according to any one of <1> to <8> having at least one of the following properties:
i) the plant fiber air filtering material with the multi-scale structure has good air permeability, and when the flow is 5L/min, the back pressure is not higher than 25Pa/cm 2 (ii) a And
ii) the plant fiber air filtering material with the multi-scale structure has a good air protection effect and can be used for treating PM in gas 2.5 Has good blocking capability, and the filtering blocking efficiency is higher than 90 percent when the flow is 10L/min.
Drawings
Fig. 1 is a digital photograph of a multi-scale structure birch fiber air filter material membrane prepared in example 1 of the present invention.
Fig. 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, in which the fibers are tightly entangled to form a dense three-dimensional network structure. In addition, the scanning chart also shows that different layers of the birch air filter material membrane with the multi-scale structure have different pore structures, namely small-scale pores with the scale of 1-100 nanometers, medium-scale pores with the scale of 0.1-1 micrometer and large-scale pores with the scale of 1-10 micrometers from inside to outside.
FIG. 3 is a flow-back pressure curve diagram of the birch fiber air filtering membrane with the multi-scale structure, and it can be seen that the birch fiber air filtering membrane with the multi-scale structure has good air permeability, and when the flow is 5L/min, the back pressure is not higher than 24Pa/cm 2 。
FIG. 4 is a flow-filtration efficiency curve diagram of a birch fiber air filtration membrane with a multi-scale structure, from which it can be seen that the birch fiber air filtration membrane with the multi-scale structure has a good air protection effect and can protect PM in gas 2.5 Has good blocking capability, and the filtering blocking efficiency is higher than 91 percent when the flow is 10L/min.
Fig. 5 is a digital photograph of a birch fiber air filter mask having a multi-scale structure according to example 1.
Fig. 6 is a digital photograph of the birch fiber protective surgical gown with the multi-scale structure prepared in the embodiment 1 of the present invention.
Detailed Description
1) Multi-scale plant fiber air filtering material
The first aspect of the application provides a multiscale plant fiber air filter material, the multiscale structure plant fiber air filter material is formed by mutually reacting abundant hydroxyl groups on the surface of fibers to form hydrogen bonds so that plant fibers with different diameters and different lengths are mutually and tightly wound and overlapped. An example of such a tightly wound lap joint is shown in figure 2. This combination promotes the formation of a dense plant fiber network. The plant fibers with various dimensions include, but are not limited to, plant nanofibers with diameters of 1-100 nanometers, plant submicron fibers with diameters of 0.1-1 micrometer, and plant micron fibers with diameters of 1-50 micrometers. Preferably, with respect to the multi-scale structure plant fiber air filtration material, the mass percentage of nanocellulose having a diameter of 100 nm or less is not less than 5%, and not more than 30% (i.e., 5 to 30 mass%, more preferably 10 to 20 mass%), the mass percentage of micro fiber having a diameter of 0.1 to 1 μm is not less than 10%, and not more than 50% (i.e., 10 to 50 mass%, more preferably 20 to 30 mass%), and the mass percentage of micro plant nanofibers having a diameter of 1 to 50 μm is not more than 85% (more preferably 50 to 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 plant submicron fibers have a diameter in the range of 1 to 50 microns, more preferably in the range of 5 to 20.
Preferably, the diameter of the plant micro-fiber is in the range of 10-500 microns, more preferably in the range of 100-300 microns.
The three plant fiber layers with gradually reduced fiber sizes are respectively provided with a large-scale pore with a large amount of 1-10 microns, a medium-scale pore with a large amount of 0.1-1 micron and a small-scale pore with a large amount of 1-100 nanometers from top to bottom (namely, the layer closest to the substrate is the lowest layer, also called the inner layer, and the layer farthest from the substrate is the uppermost layer, also called the outer layer) from the substrate side, so that the gradient distribution of the internal pores of the multi-scale plant fiber air filter material is formed. The large-pore large particle filtering material can realize large particle filtering by implementing air filtering with the large-pore surface facing outwards, and the small-pore gradient filtering effect for filtering and adsorbing small particles can be realized, and meanwhile, the inner pores of the material are not easy to be blocked, so that the good filtering effect can be kept for a long time. 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. as needed to obtain other properties.
Preferably, the large scale pores have a diameter in the range of 10-100 microns, more preferably in the range of 20-50 microns.
Preferably, the mesoscale pores have a diameter in the range of 0.1 to 10 microns, more preferably in the range of 0.5 to 5 microns.
Preferably, the small scale pores have a diameter in the range of 1 to 100 nanometers, more preferably in the range of 5 to 50 nanometers.
The macroscopic form of the plant fiber air filter material with the multi-scale structure is a membrane material.
Thereby, the multi-scale structure plant fiber air filter material has at least one of the following properties:
i) the plant fiber air filter material with the multi-scale structure has good air permeability, and when the flow is 5L/min, the back pressure is not higher than 25Pa/cm 2 ；
ii) the plant fiber air filtering material with the multi-scale structure has a good air protection effect and can be used for gas
PM 2.5 Has good blocking capability, and the filtering blocking efficiency is higher than 90 percent when the flow is 10L/min.
The term "plant fiber" refers to nano-and micro-scale fibers derived from natural plants, including, but not limited to, at least one of wood, leaves, straw, hay, hemp, bamboo, bagasse, rice hulls from natural plants.
The term "weak interaction" refers herein to hydrogen bonding interaction resulting from electrostatic interaction between atoms with large electronegativity and hydrogen atoms.
The term "back pressure" refers to the pressure received at the outlet of the fluid discharged from the system against the direction of flow.
The term "bulk porosity" refers to a porosity of up to at least 60% or more, preferably 70% or more, more preferably 90% or more.
2) The invention discloses a preparation method of a multi-scale structure plant fiber air filtering material
The second aspect of the present disclosure provides a preparation method of a plant fiber air filter material with a multi-scale structure, comprising the following steps:
A) preparing the nano-scale plant fiber, the submicron-scale plant fiber and the micron-scale plant fiber into an aqueous dispersion solution with the mass fraction of 0.1-20 percent:
B) brushing the micron-sized plant fiber aqueous dispersion on a substrate, repeatedly brushing for 1-10 times, and naturally drying for 24 hours, wherein the substrate can bear the micron-sized plant fibers and does not form strong interaction force with the plant fibers (which is beneficial to stripping the finally formed filter material), and for example, the specific example of the micron-sized plant fiber aqueous dispersion can be a metal substrate or a macromolecular filter cloth with the aperture of less than 100 nanometers;
C) brushing the submicron plant fiber aqueous dispersion on a naturally dried micron plant fiber layer, repeatedly brushing for 1-10 times, freezing, and freeze-drying in a freeze dryer;
D) uniformly spraying the nano-scale fiber aqueous dispersion on the submicron-scale plant fiber layer;
E) after being dried, for example, by baking, natural drying, freeze-drying and the like, the air filter material is taken down from the substrate, and the plant fiber air filter material with the multi-scale structure is obtained.
The term "brushing" refers to the operation of manually brushing the coating slurry with a brush.
The term "freeze drying" refers to that in the preparation method of the multi-scale structure plant fiber air filter material, the forming process is freeze drying forming. One specific embodiment thereof is: placing the material coated with the submicron plant fiber aqueous dispersion at a low temperature of below-5 ℃ to condense the aqueous dispersion into ice, and then placing the ice in a vacuum environment with the vacuum degree of below 500Pa and the temperature of 10-80 ℃ for freeze drying and forming. Another more specific embodiment is: placing the material coated with the submicron plant fiber aqueous dispersion in liquid nitrogen under normal pressure to condense the aqueous dispersion into ice, and then placing the ice in a vacuum environment with the vacuum degree below 500Pa and the temperature of 10-80 ℃ for freeze drying and forming.
The term "baking" refers to the process of drying and dehydrating the material by baking or baking under the ignition point in a dry heat manner. For baking in the preparation process of the multi-scale structure plant fiber air filter material, the drying temperature is not more than 80 ℃ so as to avoid material deformation caused by too fast volatilization of water, the heating rate is not more than 10 ℃/min, and the material deformation caused by large change of the volatilization rate of water due to too large temperature difference before and after the baking process is prevented.
The term "spray coating" refers to a coating method of applying to the surface of an object to be coated by dispersing into uniform and fine droplets by means of pressure or centrifugal force by means of a spray gun or a dish atomizer.
In the preparation method of the multi-scale structure plant fiber air filter material, the size of the plant fiber correspondingly influences the size of the pore. Meanwhile, different processes also have corresponding effects on the size of the pores. The brushing process of the large-scale and medium-scale plant fibers is beneficial to the formation of large-scale pores in the drying process because a large amount of water molecules are filled among the plant fibers. The spraying process of the small-scale plant fibers is in the form of spray water drops, so that the specific surface is larger, the volatile moisture can be quickly dried in the air, the moisture content is low when the volatile moisture falls on a substrate, and small-scale pores are formed in the drying process. The drying manner of each plant fiber layer is to better protect the pores inside the plant fiber layer and prevent the plant fiber layer from being damaged. The micron pore structure of large scale is stable, is not easy to be damaged, and can adopt a time-saving and labor-saving natural drying mode. The submicron pores with medium size can be completely preserved by freeze drying because the structure collapses and is damaged due to the surface tension generated by water volatilization in the drying process when natural drying is adopted. As for the small-scale nanometer pores, the nanometer plant fibers have specific surface and surface hydrogen bonds of the plant fibers with the far ultramicro scale and the plant fibers with the submicron scale, so that the nanometer plant fibers have extremely dense weak interaction with each other, and the nanometer pore structure can be maintained by the nanometer plant fibers, so that various drying modes can be adopted.
3) Advantages and application of plant fiber air filtering material with multi-scale structure
Compared with the melt-blown cloth-based material widely used in the market at present, the plant fiber air filter material with the multi-scale structure has a plurality of significant differences. For example, A) the melt-blown cloth-based material widely used in the market at present is directly or indirectly derived from non-renewable petroleum, while the multi-scale structure plant fiber air filtering material is a full biomass raw material, is green and degradable; B) the multi-scale structure plant fiber air filtering material is more durable in use and better in effect, most of melt-blown cloth base materials widely used in the market at present are single-scale structures, so that pores are easily blocked by harmful particulate matters such as micro-nano dust and the like in the using process, and the filtering effect is rapidly reduced; C) compared with the melt-blown fabric base material widely used in the market, the plant fiber air filtering material with the multi-scale structure has simpler process and less energy consumption; D) the multi-scale structure plant fiber air filtering material is a degradable material, is a melt-blown cloth base material widely used in the market at present, mainly comprises petroleum-based polymers, has serious environmental risks due to improper treatment, is of a full-biomass structure, and is compostable and naturally degradable.
The plant fiber air filtering material with the multi-scale structure can effectively prevent invasion of harmful substances such as bacteria, virus micro-nano dust and the like, has good air permeability and wide application prospect, and can be applied to various air purification fields such as preparation of protective masks, air purifiers, fresh air system filters, intelligent screen windows, medical protective clothing and the like.
For further understanding of the present invention, the multi-scale structure plant fiber air filter material provided by the present invention is described in detail below with reference to examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Examples
Example 1
A) Preparing birch plant nano-fiber with the diameter of 1-100 nanometers, birch plant nano-fiber with the diameter of 0.1-1 micrometer and birch plant micro-fiber with the diameter of 1-50 micrometers into 2L water slurry with the mass fraction of 0.5%, 5% and 15% respectively;
B) mechanically stirring the prepared slurry, specifically a German IKARW20 stirrer, at a rotating speed of 500 r/min for 2 hours;
C) brushing the micron-sized plant fiber aqueous dispersion on an aluminum-foil paper substrate, repeatedly brushing for 4 times, and naturally drying for 24 hours;
D) brushing the submicron plant fiber aqueous dispersion on a naturally dried micron plant fiber layer, repeatedly brushing for 6 times, freezing, and freeze-drying in a freeze dryer at 20Pa of vacuum degree and 20 ℃ of temperature:
E) uniformly spraying 3 layers of the nano-scale fiber aqueous dispersion on the submicron-scale plant fiber layer;
F) the wet film is carefully torn off from the filter cloth, then quickly and uniformly applied on the ridge baking, slowly heated to 60 ℃ at the heating rate of 5 ℃ per minute, and then kept warm for 1 hour, thus obtaining the plant fiber air filtering film with the multi-scale structure.
Fig. 1 is a digital photograph of a multi-scale structure birch fiber air filter material membrane prepared in example 1 of the present invention;
fig. 2 is a scanning electron microscope photograph of the multi-scale structure birch fiber air filter material film prepared in example 1 of the present invention, and it can be seen that the fibers of three scales are closely entangled to form a three-dimensional network structure. In addition, the scanning chart also shows that the birch air filter material membrane with the multi-scale structure has a plurality of pore structures, namely small-scale pores with the scale of 1-100 nanometers, medium-scale pores with the scale of 0.1-1 micrometer and large-scale pores with the scale of 1-10 micrometers;
FIG. 3 is a flow-back pressure curve diagram of a birch fiber air filtering membrane with a multi-scale structure, from which it can be seen that the birch fiber air filtering membrane with the multi-scale structure has good air permeability, and when the flow is 5L/min, the back pressure is not higher than 24Pa/cm 2 ；
FIG. 4 is a flow-filtration efficiency curve diagram of a birch fiber air filtration membrane with a multi-scale structure, from which it can be seen that the birch fiber air filtration membrane with the multi-scale structure has a good air protection effect and can protect PM in gas 2.5 Has good blocking capability and has a flow rate of 10L/min, the filtration and obstruction efficiency is higher than 91%.
Comparative example 1
A) Preparing birch plant nano-fibers with the diameter of 1-100 nanometers into 2L of water slurry with the mass fraction of 0.5 percent, 5 percent and 15 percent respectively;
B) mechanically stirring the prepared slurry, specifically a German IKARW20 stirrer, at a rotating speed of 500 r/min for 2 hours;
C) brushing 15% of nano-scale plant fiber aqueous dispersion on an aluminum foil paper substrate, repeatedly brushing for 4 times, and naturally drying for 24 hours;
D) brushing 5% nanometer plant fiber water dispersion on the naturally dried micron plant fiber layer, repeatedly brushing for 6 times, freezing, and freeze drying in a freeze dryer at 20Pa and 20 deg.C;
E) uniformly spraying 3 layers of 0.5 percent nano-scale fiber aqueous dispersion on the submicron-scale plant fiber layer;
F) the wet film is carefully taken off from the filter cloth, then quickly and uniformly applied on the ridge baking, slowly heated to 60 ℃ at the heating rate of 5 ℃ per minute, and then kept warm for 1 hour, thus obtaining the plant fiber air filtering film with the nano structure.
The comparative example has small-scale pores of 1-100 nm inside, poor air permeability, and back pressure higher than 50Pa/cm at flow rate of 5L/min 2 For PM in gas 2.5 Has good blocking capability, and the filtering blocking efficiency is 95% when the flow is 10L/min.
Comparative example 2
A) Preparing birch plant nanofibers with the diameters of 0.1-1 micron into 2L of aqueous slurry with the mass fractions of 0.5%, 5% and 15% respectively;
B) mechanically stirring the prepared slurry, specifically a German IKARW20 stirrer, at a rotating speed of 500 r/min for 2 hours;
C) brushing 15% submicron plant fiber aqueous dispersion on an aluminum foil paper substrate, repeatedly brushing for 4 times, and naturally drying for 24 hours;
D) brushing 5% submicron plant fiber aqueous dispersion on a naturally dried micron plant fiber layer, repeatedly brushing for 6 times, freezing, and freeze-drying in a freeze dryer at 20Pa and 20 deg.C;
E) uniformly spraying 3 layers of 0.5 percent submicron fiber aqueous dispersion on the submicron plant fiber layer;
F) the wet film is carefully torn off from the filter cloth, then quickly and uniformly applied on the baking ridge, slowly heated to 60 ℃ at the heating rate of 5 ℃ per minute, and then kept for 1 hour, thus obtaining the plant fiber air filtering film with the nano structure.
The comparative example had inside mainly mesoscale pores of 0.1 to 1 μm in size, had poor air permeability, and had a back pressure of 26Pa/cm at a flow rate of 5L/min 2 For PM in gas 2.5 Has certain blocking capacity, and the filtering blocking efficiency is 65 percent when the flow is 10L/min.
Comparative example 3
A) Preparing birch plant nano-fibers with the diameter of 1-50 microns into 2L of water-based slurry with the mass fraction of 0.5%, 5% and 15% respectively;
B) mechanically stirring the prepared slurry, specifically a German IKARW20 stirrer, at a rotating speed of 500 r/min for 2 hours;
C) brushing 15% of micron-sized plant fiber aqueous dispersion on an aluminum foil paper substrate, repeatedly brushing for 4 times, and naturally drying for 24 hours;
D) brushing 5% of micron-sized plant fiber aqueous dispersion on a naturally dried micron-sized plant fiber layer, repeatedly brushing for 6 times, freezing, and freeze-drying in a freeze dryer at 20Pa and 20 ℃;
E) uniformly spraying 3 layers of 0.5 percent micron-sized fiber aqueous dispersion on the submicron-sized plant fiber layer;
F) the wet film is carefully taken off from the filter cloth, then quickly and uniformly applied on the ridge baking, slowly heated to 60 ℃ at the heating rate of 5 ℃ per minute, and then kept warm for 1 hour, thus obtaining the plant fiber air filtering film with the nano structure.
The comparative example has large-scale pores of 1-10 μm inside, good air permeability, and back pressure lower than 20Pa/cm at flow rate of 5L/min 2 For PM in gas 2.5 The barrier capability of the filter is poor, and the filtration barrier efficiency is 33 percent when the flow is 10L/min.
Application example 1
A) The birch fiber air filter material film with the multi-scale structure obtained in the embodiment 1 is used as an intermediate filter layer, and a spunbond layer is respectively lined inside and outside the intermediate filter layer and fully ironed;
B) and (4) obtaining the birch fiber air filtering mask with the multi-scale structure through mechanical processing of a mask machine.
Fig. 5 is a digital photograph of a birch fiber air filter mask having a multi-scale structure according to example 1.
The birch fiber air filtering mask with the multi-scale structure prepared by the application example 1 has the filtering efficiency of 93% at the flow rate of 10L/min and the filtering effect of 91% at the same flow rate after 3 days of use, and the mask is excellent in usability.
Application example 2
A) The birch fiber air filter material film with the multi-scale structure obtained in the embodiment 1 is used as an intermediate filter layer, and a spunbond layer is respectively lined inside and outside the intermediate filter layer and fully ironed;
B) and (4) obtaining the birch fiber protective surgical suit with the multi-scale structure through corresponding machining.
Fig. 6 is a digital photograph of a multi-scale structure birch fiber protective surgical gown prepared by applying embodiment 1 of the present invention.
The above description of the specific embodiments and examples is only intended to facilitate an understanding of the method of the invention and its core ideas. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle and spirit of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (10)
1. A multi-scale structure plant fiber air filter material has a three-dimensional network structure formed by mutually winding and lapping a plurality of scale plant fibers, wherein the plurality of scale plant fibers at least comprise nanoscale plant fibers with the diameter of 1-100 nanometers, submicron plant fibers with the diameter of 0.1-1 micrometer and micron plant fibers with the diameter of 1-50 micrometers,
the multi-scale structure plant fiber air filtering material at least comprises a micron-scale plant fiber layer formed by the micron-scale plant fibers as an outer layer from outside to inside in sequence, a submicron-scale plant fiber layer formed by the submicron-scale plant fibers as an intermediate layer and a nanometer-scale plant fiber layer formed by the nanometer-scale plant fibers as an inner layer, wherein main body pores of the outer layer, the intermediate layer and the inner layer of the multi-scale structure plant fiber air filtering material are respectively a large-scale pore of 1-10 microns formed by mutual overlapping of the micron-scale plant fibers through hydrogen bonds, a medium-scale pore of 0.1-1 microns formed by mutual overlapping of the submicron-scale plant fibers through dense hydrogen bonds, and a small-scale pore of 1-100 nanometers formed by mutual overlapping of the nanometer-scale plant fibers through hydrogen bonds, make the inside pore gradient of material reduce gradually by the outside to inboard to realize that macropore filters and adsorbs big particulate matter, the gradient filter effect of little particulate matter is adsorbed in the filtration of aperture.
2. The multi-scale structure plant fiber air filter material of claim 1, wherein the nano-scale plant nanofibers with diameters of 1-100 nanometers account for not less than 5% and not more than 30% of the total mass of the multi-scale structure plant fiber air filter material.
3. The multi-scale structure plant fiber air filter material of claim 1, wherein the sub-micron plant nano-fibers with the diameter of 0.1-1 micron account for not less than 10% and not more than 50% of the whole multi-scale structure plant fiber air filter material by mass.
4. The multi-scale structure plant fiber air filter material of claim 1, wherein the micro-scale plant nano-fibers with the diameter of 1-50 microns account for not more than 85% of the whole multi-scale structure plant fiber air filter material by mass.
5. The multi-scale structure plant fiber air filter material of claim 1, wherein the micro-scale plant fiber layer is formed by brush coating and natural drying.
6. The multi-scale structure plant fiber air filtration material of claim 1, wherein the sub-micron plant fiber layer is formed by brush coating and freeze drying.
7. The multi-scale structure plant fiber air filter material of claim 1, wherein the nanoscale plant fiber layer is formed by spray drying.
8. The multi-scale structure plant fiber air filter material of claim 1, wherein the multi-scale structure plant fiber air filter material is a membrane material.
9. A method of making the multi-scale structure plant fiber air filter material of any one of claims 1-8, the method comprising:
A) preparing the nano-scale plant fiber, the submicron-scale plant fiber and the micron-scale plant fiber into a water dispersion solution with the mass fraction of 0.1-20%;
B) brushing the micron-sized plant fiber aqueous dispersion on a substrate, repeatedly brushing for 1-10 times, and naturally drying for 24 hours;
C) brushing the submicron plant fiber aqueous dispersion on the dried micron plant fiber layer, repeatedly brushing for 1-10 times, freezing, and freeze-drying in a freeze dryer;
D) uniformly spraying the nano-scale fiber aqueous dispersion on the submicron-scale plant fiber layer;
E) and drying and then taking down the air filter material from the substrate to obtain the plant fiber air filter material with the multi-scale structure.
10. Use of the multi-scale structure plant fiber air filtration material according to any one of claims 1 to 8 in the preparation of protective masks, air purifiers, fresh air system filters, intelligent screen windows and medical protective clothing.
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| CN116726606B9 (en) * | 2023-07-08 | 2024-08-23 | 江苏金由新材料有限公司 | Porous filter material and preparation method and application thereof |
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