Biodegradable air filter material for industrial ventilation, preparation method and application

Abstract

The invention belongs to the technical field of industrial ventilation air filtration, and particularly relates to a biodegradable air filter material for industrial ventilation, a preparation method and application. According to the biodegradable air filter material for industrial ventilation, the inertia interception layer, the high-dust-holding layer and the spunbond non-woven fabric are sequentially arranged in the air inlet direction, the inertia interception layer, the high-dust-holding layer and the spunbond non-woven fabric are all made of biodegradable materials, and the spunbond non-woven fabric can support and fix the high-dust-holding layer; the tensile strength and the dust holding capacity of the air filter material are improved by regulating and controlling the average diameter, the quantification, the thickness, the air permeability and other parameters of the fibers of the inertia interception layer and the high dust holding layer, and the air filter material is suitable for industrial ventilation.

Description

Technical Field

[0001] The present application belongs to the technical field of industrial ventilation air filtration, and more specifically, relates to a biodegradable air filter material for industrial ventilation, a preparation method and an application thereof. Background Art

[0002] In the ventilation systems of various industries such as electricity, new energy, electronics, biomedicine, beverages and food, air filters are essential key components that can effectively improve air cleanliness, ensure product quality and the stability of equipment operation. Traditional air filters use non-degradable chemical fibers or glass fibers as filter materials. In order to protect the environment, save resources, and meet the urgent needs of green environmental protection in the field of air filtration, the use of biodegradable raw materials to prepare air filter materials can alleviate the problems of carbon emissions and environmental pollution to a certain extent.

[0003] Air filter materials prepared by existing processes, such as melt-blown air filter materials and wet-formed air filter materials, have disadvantages such as poor strength or low dust holding capacity, and have many limitations in application. The industry has increased the strength of the filter material by adding glue lines, but the preparation process is more complicated and the cost of the filter material is significantly increased, which is not conducive to large-scale industrial promotion and application.

[0004] At present, there are certain technical bottlenecks in the preparation of biodegradable air filter materials for industrial ventilation. It is an urgent problem to be solved in this field to provide a biodegradable air filter material with a simple preparation method, low cost, suitable for industrial ventilation, and the air filter material can maintain a good and lasting filtering effect. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a biodegradable air filter material for industrial ventilation, a preparation method and an application, aiming to solve the technical problems of the existing air filter materials such as low tensile strength, low dust holding capacity, complex preparation process, high cost, and unsuitability for industrial ventilation.

[0006] To achieve the above-mentioned purpose, the present application provides a biodegradable air filter material for industrial ventilation, wherein an inertial interception layer, a high dust holding layer and a spunbonded nonwoven fabric are sequentially arranged along the air inlet direction; wherein the inertial interception layer, the high dust holding layer and the spunbonded nonwoven fabric are all made of biodegradable materials, and the spunbonded nonwoven fabric can support and fix the high dust holding layer;

[0007] The average diameter of the fiber filaments in the inertial interception layer is 20 to 30 μm, and the weight is 15 to 25 g / m 2 , thickness is 0.15~0.3mm, air permeability is 1500~2000mm / s;

[0008] The average diameter of the fiber filaments in the high dust holding layer is 3-6 μm, and the weight is 60-100 g / m2 , thickness is 1~3mm, and air permeability is 900~1500mm / s.

[0009] Preferably, the biodegradable material is one or more of polylactic acid, polybutylene succinate and polybutylene terephthalate-butylene adipate copolymer.

[0010] Preferably, the average diameter of the fiber filaments of the spunbonded nonwoven fabric is 20 to 30 μm, and the basis weight is 30 to 50 g / m 2 , thickness is 0.15~0.3mm, and air permeability is 2000~4000mm / s.

[0011] The present application also provides a method for preparing the above-mentioned air filter material, comprising the following steps:

[0012] S1, melt-extrude the above biodegradable material, and alternately stretch and interweave it with cold and hot air in one direction to form an inertial interception layer;

[0013] S2, melt-extrude the above-mentioned biodegradable material, and stretch it with hot air in at least three directions, so that the extruded fiber filaments are interwoven with the inertial interception layer as the base material to form a three-dimensional structure, i.e., a high dust holding layer; the average diameter of the fiber filaments in the high dust holding layer is smaller than the average diameter of the fiber filaments in the inertial interception layer;

[0014] S3. Stacking the spunbonded nonwoven fabric on the high dust holding layer, and ultrasonically bonding the fabric to obtain a biodegradable air filter material for industrial ventilation.

[0015] Preferably, in step S1, in the above-mentioned alternating cold and hot air stretching, the temperature of the cold air is 5-15°C, the temperature of the hot air is 120-140°C, the alternating interval of the cold and hot air is 1-2s, and the pressures of the cold air and the hot air are independently 0.5-0.8MPa.

[0016] Preferably, in step S1, the biodegradable material is melt-extruded and subjected to hot air drawing in three directions or hot air drawing in four directions, so that the extruded fiber filaments are interwoven with the inertial interception layer as a base material to form a three-dimensional structure, i.e., a high dust holding layer;

[0017] In the above three-directional hot air stretching, the first direction is parallel to the extrusion direction, the second direction and the third direction are at different angles to the first direction, and at least one of the second direction and the third direction is not in the same plane as the first direction;

[0018] In the above four directions of hot air stretching, the first direction is parallel to the extrusion direction, the second direction, the third direction and the fourth direction each have a different angle with the first direction, and at least one of the second direction, the third direction and the fourth direction is not in the same plane with the first direction.

[0019] Further preferably, in the above three-directional hot air stretching, the angles between the second direction and the third direction and the first direction are independently 30° to 45°.

[0020] Further preferably, in the above four-directional hot air stretching, the angles between the second direction, the third direction and the fourth direction and the first direction are independently 30° to 45°.

[0021] Preferably, in the three-directional hot air stretching or the four-directional hot air stretching, the temperature of the hot air is 180-200° C., and the pressure of the hot air is 0.5-0.8 MPa.

[0022] Preferably, in step S3, the frequency of the ultrasonic wave is 20 to 40 kHz, and the duration is 5 to 10 seconds.

[0023] The present application also provides an industrial ventilation device comprising the above-mentioned air filter material.

[0024] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

[0025] (1) The biodegradable air filter material for industrial ventilation provided in the present application is provided with an inertial interception layer, a high dust holding layer and a spunbond non-woven fabric in sequence along the air inlet direction, wherein the inertial interception layer, the high dust holding layer and the spunbond non-woven fabric are all made of biodegradable materials, and the spunbond non-woven fabric can support and fix the high dust holding layer. By adjusting the average diameter, quantity, thickness and air permeability of the fiber filaments of the inertial interception layer and the high dust holding layer, the tensile strength and dust holding capacity of the air filter material are improved, and the air filter material is suitable for industrial ventilation.

[0026] (2) The present application forms an inertial interception layer by alternately stretching and interweaving the biodegradable material with hot and cold air in one direction, and uses the inertial interception layer as a carrier to stretch and interweave the biodegradable material with hot air in at least three directions to form a three-dimensional staggered interweaving structure, i.e., a fluffy high dust holding layer, wherein the average diameter of the fiber filaments of the inertial interception layer is greater than the average diameter of the fiber filaments of the high dust holding layer, the inertial interception layer can intercept larger pollutants and play a preliminary filtering role for the air, and the high dust holding layer has a high dust holding capacity and can filter the air efficiently, improving the filtering performance, and then combined with a spunbond fiber cloth that can support and reinforce the high dust holding layer, to prepare a biodegradable air filter material with high tensile strength, high dust holding capacity, and suitable for industrial ventilation. Compared with the prior art, the present application has a simple preparation process, low cost, and is suitable for large-scale production.

[0027] (3) In the preferred embodiment, the present application adjusts the process parameters such as the temperature of the cold air, the temperature of the hot air, and the time of the alternating interval in the cold and hot air alternating drafting, and coordinately regulates the toughness and mechanical strength of the fiber filaments of the inertial interception layer and the quantity and thickness of the inertial interception layer, so as to ensure the high air permeability of the inertial interception layer while improving the tensile strength and reducing the air circulation resistance, so that the inertial interception layer has excellent filtering performance, high filtering efficiency, high tensile strength, and maintains a good filtering effect under a high pressure difference. In addition, by regulating the process parameters for preparing high dust holding capacity, a high dust holding layer with a fluffy structure and a small average diameter of the fiber filaments is prepared, and the dust holding capacity is increased while the filtering efficiency is improved. In practical applications, the air filtration time can be effectively shortened and the service life of the air filter material can be increased. On this basis, the inertial interception layer, the high dust holding layer and the spunbonded fiber cloth are combined, and the high-efficiency filtering and long-lasting filtering performance of the biodegradable air filter material are achieved through the synergistic effect between the layers, which can be used for industrial ventilation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view of the biodegradable air filter material for industrial ventilation prepared in the present application, wherein 1 is an inertial interception layer, 2 is a high dust holding layer, and 3 is a spunbond nonwoven fabric;

[0029] Figure 2 This is a flow chart for preparing biodegradable air filter material for industrial ventilation provided in this application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0031] In the present application, the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0032] The term "single direction cold and hot air alternate drawing" means that when the biodegradable material is melted and extruded from the spinneret, cold air with a certain pressure and hot air with a certain pressure are alternately used to stretch the ejected fiber until the diameter of the stretched fiber reaches the target requirement. Among them, "single direction" refers to the direction parallel to the filament output direction.

[0033] The term "three-direction hot air drawing" means that when the biodegradable material is melted and extruded from the spinneret, it is drawn from three different directions using hot air with a certain pressure, so that the filaments are arranged in different directions to form a three-dimensional staggered interwoven structure, i.e., a fluffy structure. The "three directions" means that the first direction is parallel to the extrusion direction, the second direction and the third direction are at different angles to the first direction, and at least one of the second direction and the third direction is not in the same plane as the first direction.

[0034] The term "four-direction hot air drawing" means that when the biodegradable material is melted and extruded from the spinneret, it is drawn from four different directions using hot air with a certain pressure, so that the filaments are arranged in different directions to form a three-dimensional staggered interlaced structure, i.e., a fluffy structure. The "four directions" means that the first direction is parallel to the extrusion direction, the second direction, the third direction and the fourth direction each have a different angle with the first direction, and at least one of the second direction, the third direction and the fourth direction is not in the same plane as the first direction.

[0035] The present application provides a biodegradable air filter material for industrial ventilation (cross-sectional view as shown in FIG. Figure 1 As shown), an inertial interception layer, a high dust holding layer and a spunbonded nonwoven fabric are sequentially arranged along the air inlet direction; wherein the inertial interception layer, the high dust holding layer and the spunbonded nonwoven fabric are all made of biodegradable materials, and the spunbonded nonwoven fabric can support and fix the high dust holding layer;

[0036] The average diameter of the fiber filaments in the inertial interception layer is 20 to 30 μm, and the weight is 15 to 25 g / m 2 , thickness is 0.15~0.3mm, air permeability is 1500~2000mm / s;

[0037] The average diameter of the fiber filaments in the high dust holding layer is 3-6 μm, and the weight is 60-100 g / m 2 , thickness is 1~3mm, and air permeability is 900~1500mm / s.

[0038] In some embodiments, the biodegradable material is one or more of polylactic acid, polybutylene succinate and polybutylene terephthalate-adipate copolymer.

[0039] In some embodiments, the average diameter of the fiber filaments of the spunbonded nonwoven fabric is 20 to 30 μm, and the basis weight is 30 to 50 g / m 2, thickness is 0.15~0.3mm, air permeability is 2000~4000mm / s. In the present application, the above-mentioned spunbond nonwoven fabric can support and reinforce the high dust holding layer, prevent the high dust holding layer from breaking and falling off, and maintain the structural strength of the air filter material without negatively affecting the filtering effect of the air filter material. It is understandable that the present application does not limit the source of the above-mentioned spunbond nonwoven fabric, which can be purchased from commercial products or prepared by the laboratory.

[0040] The present application provides a method for preparing the above-mentioned air filter material (such as Figure 2 ), comprising the following steps:

[0041] S1, melt-extrude the above biodegradable material, and alternately stretch and interweave it with cold and hot air in one direction to form an inertial interception layer;

[0042] S2, melt-extrude the above-mentioned biodegradable material, and stretch it with hot air in at least three directions, so that the extruded fiber filaments are interwoven with the above-mentioned inertial interception layer as a base material to form a three-dimensional structure, i.e., a high dust holding layer; wherein the average diameter of the fiber filaments of the inertial interception layer is greater than the average diameter of the fiber filaments of the high dust holding layer;

[0043] S3. Stacking the spunbonded nonwoven fabric on the high dust holding layer, and ultrasonically bonding the fabric to obtain a biodegradable air filter material for industrial ventilation.

[0044] In some embodiments, in step S1, in the above-mentioned cold and hot air alternate drawing, the pressure of the cold air and the hot air are independently 0.5-0.8 MPa. It is understood that the field can appropriately increase or decrease the pressure according to the actual production situation, which is within the protection scope of this application.

[0045] In some embodiments, in step S1, in the above-mentioned cold and hot air alternating stretching, the temperature of the cold air is 5-15°C, the temperature of the hot air is 120-140°C, and the cold and hot air alternating interval is 1-2s. The present application coordinately regulates the toughness and mechanical strength of the fiber filaments of the inertial interception layer, as well as the quantity and thickness of the inertial interception layer by adjusting the process parameters such as the temperature of the cold air, the temperature of the hot air, and the alternating interval time in the cold and hot air alternating stretching, so as to ensure the high air permeability of the inertial interception layer while improving the tensile strength and reducing the air circulation resistance, so that the inertial interception layer has excellent filtering performance, high filtering efficiency, high tensile strength, and maintains a good filtering effect under a relatively high pressure difference. It can be used for industrial ventilation and play a role in preliminary air filtering.

[0046] In some embodiments, in step S2, the biodegradable material is melt-extruded and subjected to hot air drawing in three directions or hot air drawing in four directions, so that the extruded fiber filaments are interwoven with the inertial interception layer as the base material to form a three-dimensional staggered interwoven structure, i.e., a high dust holding layer;

[0047] In the three-directional hot air stretching, the first direction is parallel to the extrusion direction, the second direction and the third direction are at different angles to the first direction, and at least one of the second direction and the third direction is not in the same plane as the first direction;

[0048] In the above four directions of hot air stretching, the first direction is parallel to the extrusion direction, the second direction, the third direction and the fourth direction each have a different angle with the above first direction, and at least one of the second direction, the third direction and the fourth direction is not in the same plane with the above first direction.

[0049] In some embodiments, during the three-directional hot air stretching or the four-directional hot air stretching, the pressure of the hot air is 0.5-0.8 MPa and the temperature is 180-200°C.

[0050] In some embodiments, in the above three-directional hot air stretching, the angles between the second direction and the third direction and the first direction are independently 30° to 45°.

[0051] In some embodiments, in the above four-directional hot air stretching, the angles between the second direction, the third direction and the fourth direction and the first direction are independently 30° to 45°.

[0052] The present application adjusts the direction of hot air stretching in the above-mentioned step S2 so that the average diameter of the fiber filaments in the prepared high dust holding layer is smaller and the structure is fluffy, which can achieve more efficient air filtration and greatly increase the dust holding capacity. In actual application, it can effectively shorten the air filtration time and increase the service life of the air filter material.

[0053] In some embodiments, in step S3, the frequency of the ultrasonic wave is 20-40 kHz, and the duration is 5-10 s.

[0054] The present application also provides the application of the above-mentioned air filter material in industrial ventilation.

[0055] The present application further provides an industrial ventilation device comprising the above-mentioned air filter material.

[0056] The above technical solutions are described in detail below in conjunction with specific embodiments. It should be understood that these are merely exemplary and are not intended to limit the present application. Materials identical or similar to the types, models, qualities, properties or functions of the following reagents and instruments can be used to implement the present application. The experimental methods used in the following embodiments are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial sources.

[0057] The following are examples and comparative examples:

[0058] Example 1

[0059] The method for preparing the biodegradable air filter material for industrial ventilation provided in this embodiment specifically comprises the following steps:

[0060] S1. Heat the dry polymer PBS to a molten state, extrude it and form an inertial interception layer by alternately drawing and interweaving cold and hot air in one direction; wherein the temperature of the cold air is 10°C, the temperature of the hot air is 130°C, the cold / hot air alternating interval is 1s, the pressure of the cold / hot air is 0.6MPa, and the average diameter of the fiber filaments of the formed inertial interception layer is 25μm and the basis weight is 20g / m 2 , thickness is 0.2mm, air permeability is 1500mm / s.

[0061] S2, heating the dried polymer PLA to a molten state, extruding it and stretching it through hot air in three directions, wherein the first direction is parallel to the filament output direction, the second direction and the third direction are at angles of 30° and 45° to the first direction respectively, and the second direction and the third direction are not in the same plane as the first direction, and the inertial interception layer of step S1 is used as the substrate, and a fluffy high dust holding layer is formed on it by interweaving; wherein the temperature of the hot air is 180°C, the pressure is 0.6MPa, and the average diameter of the fiber filaments of the formed high dust holding layer is 5μm, and the basis weight is 60g / m 2 , thickness is 2mm, air permeability is 1200mm / s.

[0062] S3, superimposing a spunbonded nonwoven fabric made of PBAT on the composite filter layer of step S2 for ultrasonic bonding, wherein the fiber filaments of the spunbonded nonwoven fabric have an average diameter of 20 μm and a basis weight of 30 g / m 2 , thickness is 0.3mm, air permeability is 3000mm / s; the frequency of ultrasonic bonding is 40kHz, the time is 5s, and a biodegradable air filter material for industrial ventilation is prepared.

[0063] Example 2

[0064] The method for preparing the biodegradable air filter material for industrial ventilation provided in this embodiment specifically comprises the following steps:

[0065] S1. Heat the dry polymer PLA to a molten state, extrude it and form an inertial interception layer by alternately drawing and interweaving cold and hot air in one direction; wherein the temperature of the cold air is 5°C, the temperature of the hot air is 140°C, the interval between cold and hot air alternation is 1s, and the pressure of the cold and hot air is 0.5MPa. The average diameter of the fiber filaments in the formed inertial interception layer is 20μm and the basis weight is 25g / m 2 , thickness is 0.15mm, air permeability is 1800mm / s.

[0066] S2, heating the dried polymer PBAT to a molten state, extruding and stretching it through hot air in four directions, the first direction is parallel to the filament direction, the second direction, the third direction, and the fourth direction are respectively at angles of 30°, 40°, and 45° with the first direction, and the second direction is not in the same plane as the first direction, taking the inertial interception layer of step S1 as the substrate, interweaving it to form a fluffy high dust holding layer; wherein the temperature of the hot air is 200°C, the pressure is 0.5MPa, and the average diameter of the fiber filaments of the formed high dust holding layer is 6μm and the quantitative is 100g / m 2 , thickness is 3mm, air permeability is 1500mm / s.

[0067] S3, superimposing a spunbonded nonwoven fabric made of PBS on the composite filter layer of step S2 for ultrasonic bonding, wherein the average diameter of the fiber filaments of the spunbonded nonwoven fabric is 30 μm and the basis weight is 40 g / m 2 , thickness is 0.15mm, air permeability is 2000mm / s; the frequency of ultrasonic bonding is 30kHz, the time is 8s, and a biodegradable air filter material for industrial ventilation is prepared.

[0068] Example 3

[0069] The method for preparing the biodegradable air filter material for industrial ventilation provided in this embodiment specifically comprises the following steps:

[0070] S1. Heat the dry polymer PBAT to a molten state, extrude it and form an inertial interception layer by alternately drawing and interweaving cold and hot air in one direction; wherein the temperature of the cold air is 15°C, the temperature of the hot air is 120°C, the cold / hot air alternating interval is 2s, the pressure of the cold / hot air is 0.7MPa, and the average diameter of the fiber filaments of the formed inertial interception layer is 30μm and the basis weight is 15g / m 2 , thickness is 0.3mm, air permeability is 2000mm / s.

[0071] S2, heating the dried polymer PLA to a molten state, extruding it and stretching it through hot air in three directions, wherein the first direction is parallel to the filament output direction, the second direction and the third direction are at angles of 30° and 45° to the first direction respectively, and the second direction is not in the same plane as the first direction, and the inertial interception layer of step S1 is used as the substrate, and a fluffy high dust holding layer is formed on it by interweaving; wherein the temperature of the hot air is 180°C, the pressure is 0.7MPa, and the average diameter of the fiber filaments of the formed high dust holding layer is 3μm, and the weight is 60g / m 2 , thickness is 1mm, air permeability is 900mm / s.

[0072] S3, superimposing a spunbonded nonwoven fabric made of PBS on the composite filter layer of step S2 for ultrasonic bonding, wherein the average diameter of the fiber filaments of the spunbonded nonwoven fabric is 30 μm and the basis weight is 50 g / m 2 , thickness is 0.20mm, air permeability is 4000mm / s; the frequency of ultrasonic bonding is 20kHz, the time is 10s, and a biodegradable air filter material for industrial ventilation is prepared.

[0073] Comparative Example 1

[0074] The preparation method of the biodegradable air filter material provided in the comparative example of the present application does not have step S1, and other operations are the same as those in Example 1.

[0075] Comparative Example 2

[0076] The preparation method of the biodegradable air filter material provided in the comparative example of the present application does not have step S3, and other operations are the same as those in Example 1.

[0077] Comparative Example 3

[0078] In step S1, the dry polymer PBS is heated to a molten state, extruded and interwoven by unidirectional cold air drawing to form an inertial interception layer. Other operations are the same as those in Example 1.

[0079] Comparative Example 4

[0080] In step S1, the dry polymer PBS is heated to a molten state, extruded and interwoven by unidirectional hot air drawing to form an inertial interception layer. Other operations are the same as those in Example 1.

[0081] Comparative Example 5

[0082] In step S1, the dry polymer PBS is heated to a molten state, extruded and interwoven by unidirectional cold and hot air stretching to form an inertial interception layer, wherein the cold / hot air interleaving interval is 3s, and other operations are the same as in Example 1.

[0083] Comparative Example 6

[0084] In step S1, the dry polymer PBS is heated to a molten state, extruded and interwoven by unidirectional cold and hot air drawing to form an inertial interception layer, wherein the cold / hot air interleaving interval is 0.5s, and other operations are the same as in Example 1.

[0085] Comparative Example 7

[0086] In step S2, the dried polymer PLA is heated to a molten state, extruded and stretched by hot air in a single direction (parallel to the filament output direction), and a dust holding layer is formed by interweaving the inertial interception layer of step S1 as a substrate. Other operations are the same as those in Example 1.

[0087] Comparative Example 8

[0088] In step S2, the dried polymer PLA is heated to a molten state, extruded and stretched by hot air in two directions, the first direction is parallel to the filament output direction, the second direction is at an angle of 30° to the first direction, and the second direction is not in the same plane as the first direction. The inertial interception layer of step S1 is used as the base material to form a dust holding layer. Other operations are the same as those in Example 1.

[0089] Comparative Example 9

[0090] In step S2, the dried polymer PLA is heated to a molten state, extruded and stretched by hot air in three directions, the first direction is parallel to the filament output direction, the second direction and the third direction are at angles of 30° and 45° to the first direction respectively, the first direction, the second direction and the third direction are located in the same plane, and the inertial interception layer of step S1 is used as the base material to form a dust holding layer through interweaving, and other operations are the same as those in Example 1.

[0091] Comparative Example 10

[0092] The ultrasonic bonding frequency in step S3 is 15 kHz, and other operations are the same as those in embodiment 1.

[0093] Comparative Example 11

[0094] The ultrasonic bonding frequency in step S3 is 45 kHz, and other operations are the same as those in embodiment 1.

[0095] The performance of the air filter materials prepared in Examples 1 to 3 and Comparative Examples 1 to 11 was tested under the following test conditions. The test results are shown in Table 1:

[0096] 1) Tensile strength: tested according to standard GB / T 12914-2018;

[0097] 2) Dust holding capacity: Tested according to standard ISO 5011:2020, the final pressure drop is 450Pa.

[0098] Table 1 Performance of air filter materials prepared in Examples 1 to 3 and Comparative Examples 1 to 11

[0099] Tensile strength(kN / m) <![CDATA[Dust holding capacity (g / m 2 )]]> Example 1 3.5 56 Example 2 3.7 54 Example 3 3.9 52 Comparative Example 1 2.3 36 Comparative Example 2 1.1 54 Comparative Example 3 2.6 56 Comparative Example 4 2.2 56 Comparative Example 5 2.1 56 Comparative Example 6 2.3 56 Comparative Example 7 3.9 12 Comparative Example 8 3.5 16 Comparative Example 9 3.5 17 Comparative Example 10 2.3 56 Comparative Example 11 2.6 42

[0100] It can be seen from Table 1 that the tensile strength of the biodegradable air filter material prepared by the method provided in this application is greater than 3kN / m, and the dust holding capacity is greater than 50g / m 2 , has greater tensile strength and higher dust holding capacity, and is suitable for industrial ventilation. In addition, the air filter material prepared in this application can be used in static filtration scenarios, that is, the air filter material is used to capture dust to complete the filtration. Compared with the dynamic filtration scenario, this application does not need to increase the total dust holding capacity of the air filter material through back-blowing self-cleaning, which can save the energy consumption of back-blowing self-cleaning.

[0101] Compared with Example 1, the lack of the inertial interception layer in Example 1 results in a decrease in the dust holding capacity of the air filter material and a significant decrease in the tensile strength; the lack of the spunbond non-woven fabric in Example 2 cannot provide support and fixation for the high dust holding layer, resulting in a sharp decrease in the structural strength of the air filter material. In actual use, the high dust holding layer may rupture or fall off, causing the air filter material to lose its filtering effect and affecting the durability of the air filter material.

[0102] The tensile strength of Example 1 is better than that of Comparative Examples 3 to 6. The possible reason may be that, by extruding the molten polymer PBS and stretching it in one direction with alternating hot and cold air, and synergistically controlling the alternating frequency of hot and cold air, the fibers forming the inertial interception layer have higher toughness and mechanical strength, and the fiber diameter has good consistency, thereby improving the tensile strength and ensuring that the air filter material maintains a good filtering effect under a higher pressure difference.

[0103] The tensile strength of comparative example 7 is better than that of example 1, and the dust holding capacity is only 12g / m 2 , which is significantly lower than Example 1. This may be because Example 7 forms a dense dust-holding layer by extruding the molten polymer PLA and performing unidirectional hot air stretching, which leads to a sharp decrease in dust holding capacity while improving the tensile strength to a certain extent. The dust holding capacity of Examples 8 and 9 is higher than that of Example 7, but still lower than that of Example 1, indicating that a dust-holding layer with a fluffy structure cannot be formed by using two-directional hot air stretching or three-directional hot air stretching on the same plane. The present application regulates the direction of hot air stretching and the plane position of hot air in different directions, so that the fibers are interwoven in multiple dimensions to form a fluffy dust-holding layer, which can accommodate more pollutants, increase the dust holding capacity, and improve the filtration efficiency. In practical applications, it can effectively shorten the air filtration time and save time costs.

[0104] Comparing Comparative Example 10 and Comparative Example 11 with Example 1, it can be seen that when using ultrasound to bond the spunbond non-woven fabric and the composite filter layer, if the ultrasonic power is too small, it will affect the interlayer bonding force of the filter material, resulting in a decrease in tensile strength; if the ultrasonic power is too large, it will penetrate the filter material, thereby affecting the strength performance and dust holding performance of the air filter material.

[0105] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A biodegradable air filter material for industrial ventilation, characterized in that: An inertial interception layer, a high dust holding layer and a spunbonded nonwoven fabric are sequentially arranged along the air inlet direction; wherein the inertial interception layer, the high dust holding layer and the spunbonded nonwoven fabric are all made of biodegradable materials, and the spunbonded nonwoven fabric can support and fix the high dust holding layer; The average diameter of the fiber filaments in the inertial interception layer is 20-30 μm, and the basis weight is 15-25 g / m 2 , thickness is 0.15~0.3mm, air permeability is 1500~2000mm / s; The average diameter of the fiber filaments in the high dust holding layer is 3-6 μm, and the basis weight is 60-100 g / m 2 , thickness is 1~3mm, and air permeability is 900~1500mm / s.

2. The air filter material according to claim 1, characterized in that: The biodegradable material is one or more of polylactic acid, polybutylene succinate and polybutylene terephthalate-butylene adipate copolymer.

3. The air filter material according to claim 1, characterized in that: The average diameter of the fiber filaments of the spunbonded nonwoven fabric is 20 to 30 μm, and the basis weight is 30 to 50 g / m 2 , thickness is 0.15~0.3mm, and air permeability is 2000~4000mm / s.

4. A method for preparing an air filter material according to any one of claims 1 to 3, characterized in that: The steps include: S1, melt-extrude the biodegradable material, and alternately stretch and interweave the biodegradable material with hot and cold air in one direction to form an inertial interception layer; S2, melt-extrude the biodegradable material, and stretch it with hot air in at least three directions, so that the extruded fiber filaments are interwoven with the inertial interception layer as a base material to form a three-dimensional structure, i.e., a high dust holding layer; the average diameter of the fiber filaments of the high dust holding layer is smaller than the average diameter of the fiber filaments of the inertial interception layer; S3, stacking the spunbonded nonwoven fabric on the high dust holding layer, and ultrasonically bonding the fabric to obtain a biodegradable air filter material for industrial ventilation.

5. The preparation method according to claim 4, characterized in that: In step S1, during the cold and hot air alternating stretching, the temperature of the cold air is 5-15°C, the temperature of the hot air is 120-140°C, and the interval between the cold and hot air alternation is 1-2s.

6. The preparation method according to claim 4, characterized in that: In step S2, the biodegradable material is melt-extruded and subjected to hot air drawing in three directions or hot air drawing in four directions, so that the extruded fiber filaments are interwoven with the inertial interception layer as a base material to form a three-dimensional structure, i.e., a high dust holding layer; In the three-directional hot air stretching, the first direction is parallel to the extrusion direction, the second direction and the third direction are at different angles to the first direction, and at least one of the second direction and the third direction is not in the same plane as the first direction; In the four-directional hot air stretching, the first direction is parallel to the extrusion direction, the second direction, the third direction and the fourth direction each have a different angle with the first direction, and at least one of the second direction, the third direction and the fourth direction is not in the same plane with the first direction.

7. The preparation method according to claim 6, characterized in that: In the three-directional hot air stretching or the four-directional hot air stretching, the temperature of the hot air is 180-200°C.

8. The preparation method according to claim 6, characterized in that: In the three-directional hot air stretching, the angles between the second direction and the third direction and the first direction are independently 30° to 45°; and / or, In the four-directional hot air stretching, the angles between the second direction, the third direction and the fourth direction and the first direction are independently 30° to 45°.

9. The preparation method according to claim 4, characterized in that: In step S3, the frequency of the ultrasonic wave is 20 to 40 kHz, and the duration is 5 to 10 seconds.

10. An industrial ventilation device comprising the air filter material according to any one of claims 1 to 3.

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