An electret film, a structuring method, and an air filter

Abstract

The present application relates to air filtration technology, specifically to a kind of electret film, structural treatment method and air filter, including the following mass percentage of components: polypropylene 80-85%; Antibacterial and mildew-proof master batch 5-7%; Flame-retardant master batch 5-8%; Calcium stearate 0.5-2%; Light stabilizer 0.5-1.5%; Antioxidant 1.5-3%; Alpha nucleating agent 0.1-0.5%; Silicon dioxide 0.1-0.5%. Compared with prior art, the present application solves the problem that in prior art, external power supply or high-voltage power supply is needed to generate high-voltage electrostatic field to carry out dust removal.

Description

TECHNICAL FIELD

[0001] The present application relates to air filtration technology, in particular to an electret film, a structural treatment method and an air filter. BACKGROUND

[0002] At present, the dust removal methods of household air conditioners and central air conditioners generally adopt coarse and medium efficiency non-woven fabric filtration, coarse and medium efficiency silk screen filtration and electrostatic dust removal (ESP), etc. The disadvantage of coarse and medium efficiency non-woven fabric filtration is low filtration efficiency, and the higher the grade of non-woven fabric filter screen or filter, the greater the air resistance. In the process of ionization of ESP, ozone is inevitably generated, forming secondary pollution and damaging human health.

[0003] CN108654840A discloses a corrugated dielectric electrostatic dust removal filter element and a manufacturing method thereof, but the method adopts the mode of processing conductive coating material on the substrate, generating a high-voltage electrostatic field through an external high-voltage power supply, thereby achieving the effect of dust removal. Once the external high-voltage power supply is removed, the filter element basically does not have any dust removal effect, making it not have good versatility.

[0004] The existing electret film needs to be connected to an external power supply when used for air filtration and dust removal, and even needs to be connected to a high-voltage power supply, which is very inconvenient for use in portable air filters. Therefore, it is necessary to manufacture an air filter that can meet the requirements of antibacterial, flame retardant, no ozone generation, and no need for external high-voltage power supply. SUMMARY

[0005] The purpose of the present application is to solve at least one of the above problems by providing an electret film, a structural treatment method and an air filter to solve the problem that an external power supply or a high-voltage power supply is needed to generate a high-voltage electrostatic field for dust removal in the prior art.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The present application discloses an electret film in the first aspect, which comprises the following components by mass percentage:

[0008]

[0009]

[0010] Preferably, the antibacterial and mildew-proof master batch is composed of polypropylene and an antibacterial agent, wherein the antibacterial agent is a composite antibacterial agent with silicate or zeolite as a carrier and silver or zinc loaded.

[0011] Preferably, the flame-retardant master batch is composed of polypropylene and a flame retardant, wherein the flame retardant comprises one or more of phosphorus-nitrogen flame retardants, halogen flame retardants or metal hydroxide flame retardants.

[0012] The phosphorus-nitrogen flame retardant can be melamine polyphosphate, the metal hydroxide flame retardant can be aluminum hydroxide or magnesium hydroxide, and the halogen flame retardant can be decabromodiphenyl ethane.

[0013] Preferably, the electret film is processed into a film roll through a flow forming process.

[0014] The second aspect of the present application discloses a method for structuring the electret film as described in any of the above, comprising the following steps:

[0015] S1: forming: the electret film is respectively processed into a corrugated structure and a flat structure through a rolling forming device;

[0016] S2: electretizing: the electret film after step S1 is sent into an electrostatic electret device for electretizing;

[0017] S3: cutting: the electret film after step S2 is cut;

[0018] S4: stacking: the electret film after step S3 is alternately stacked according to the corrugated structure and the flat structure to form a stacked electret film;

[0019] S5: bonding: the stacked electret film obtained in step S4 is placed in a hot cutting and bonding device for melt bonding and slitting to form a filter core semi-product;

[0020] S6: cutting: the filter core semi-product obtained in step S5 is cut to form an air filter.

[0021] Preferably, in step S1, the rolling forming device uses high-temperature corrugated rollers and high-temperature rollers for rolling processing of the corrugated structure and the flat structure, the temperature of the heating area is 160-200℃, and the production line speed is 0.5-5m / min.

[0022] Preferably, in step S2, a direct current high-voltage power supply is used for electretizing, and the output voltage range is 0-100kV; the electret rod for electretizing is composed of a fixed bar and a plurality of electret needles, the diameter of the electret needle is 0.5-2mm, the exposed length of the electret needle after being inserted into the fixed bar is 10-20mm, and the spacing of the electret needles is 5-20mm; during the electretizing process, 4-10 electret rods are respectively arranged on both sides of the electret film, the spacing between the electret rods is 50-150mm, and the production line speed is 0.5-5m / min.

[0023] Preferably, the fixed strip is an aluminum alloy square strip.

[0024] Preferably, the distance between the electret needle and the electret film is adjustable, and the adjustment range is 50-150mm.

[0025] Preferably, in step S5, the electric heating wire of the hot cutting and bonding device is Cr 20 Ni 80 , the diameter is 0.3-0.6mm, the working voltage is DC 10-24V, and the hot cutting speed is 30-150mm / min (the corresponding stepping motor frequency is 1-5Hz).

[0026] Preferably, in step S5, the end surface of the corrugated structure electret film and the flat structure electret film in contact is formed into an arch bridge shape after fusion bonding. Through hot melting processing, the corrugated structure electret film and the flat structure electret film are bonded into one, and an arch bridge shape is formed at the intersection, which has high structural strength, so that the electret film can be structured.

[0027] The third aspect of the present application discloses an air filter obtained by the above-mentioned structured processing method.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The electret film is used as a carrier, and dust particles are adsorbed by the action of its own electrostatic field, without the need for an external high-voltage power supply. It can be used in the filter device or part of a household air conditioner or central air conditioner to filter and adsorb PM particulate matter in the air. The mixed antibacterial and mildew-resistant master batch and the flame-retardant master batch have good compatibility, so that the electret film also has excellent antibacterial, antimicrobial and flame-retardant properties.

[0030] (2) A large number of channels are formed by the alternately stacked corrugated structure and flat structure, which not only solves the problems of poor filtering effect, large wind resistance, high maintenance cost, ozone generation and secondary pollution of traditional filter screens or filters, but also fully adsorbs small particles in the air due to the space charge and surface charge formed inside (between molecules) and on the surface of the film in the channel, thereby playing a role in filtering PM2.5 without the need for an external high-voltage power supply. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a front view structural schematic diagram of an air filter in an embodiment of the present application;

[0032] Figure 2 is a front view structural schematic diagram of an air filter in an embodiment of the present application;

[0033] Figure 3Structure diagram of the corrugated structure of the electret film in one embodiment of the present application;

[0034] Figure 4 Structure diagram of the flat structure of the electret film in one embodiment of the present application;

[0035] Figure 5 Structure diagram of the stacked electret film in one embodiment of the present application;

[0036] Figure 6 Structure diagram of the stacked electret film in one embodiment of the present application;

[0037] Figure 7 Structure diagram of the stacked electret film in one embodiment of the present application;

[0038] Figure 8 Structure diagram of the stacked electret film in one embodiment of the present application;

[0039] Figure 9 Structure diagram of the stacked electret film in one embodiment of the present application;

[0040] Figure 10 Structure diagram of the stacked electret film in one embodiment of the present application;

[0041] In the figure: 1-electret film; 11-flat structure of the electret film; 12-corrugated structure of the electret film; 20-stacked electret film; 30-structured electret film; 50-aluminum alloy square bar; 51-electret needle; 52-roller. DETAILED DESCRIPTION

[0042] The present application will be described in detail below with reference to the accompanying drawings and specific examples.

[0043] In the following examples and comparative examples, the reagents and methods used are commercially available and can be obtained by conventional means by those skilled in the art, unless otherwise specified.

[0044] The following examples and comparative examples were prepared by the following method, and the specific formulations used in each example are shown in Table 1. The specific steps are as follows: S1. Provide the electret film 1 formulation (mass percent):

[0045]

[0046] The antibacterial and mildew-proof master batch is composed of effective components polypropylene and antibacterial agent (silicate / zeolite loaded silver / zinc composite antibacterial agent);

[0047] The flame-retardant master batch is composed of effective components homopolymer PP and flame retardant (phosphorus-nitrogen flame retardant, such as melamine polyphosphate, decabromodiphenyl ethane, halogen flame retardant, or metal hydroxide flame retardant, such as aluminum hydroxide, magnesium hydroxide, one or more of them);

[0048] The raw materials are processed into film roll by a flow casting process.

[0049] Table 1 discloses the formulations used in Examples 1-3 and Comparative Examples 1-3 and the grade of reagents used.

[0050] Table 1 Formulations (wt%) of Examples 1-3 and Comparative Examples 1-3

[0051]

[0052] The electret films 1 prepared in the following examples and comparative examples are tested for antibacterial rate according to GB 21551.2-2010 (Appendix A film sticking method), for antifungal performance according to GB 21551.2-2010 (Appendix C), and for flame retardant grade according to UL-900, and the test results are shown in Tables 2 and 3.

[0053] Table 2 Test results of antibacterial and antifungal properties of Examples 1-3 and Comparative Examples 1-3

[0054]

[0055]

[0056] Table 3 Test results of flame retardant grade of Examples 1-3 and Comparative Examples 1-3

[0057] Flame retardant rating Example 1 VTM-1 Example 2 VTM-1 Example 3 VTM-1 Comparative Example 1 VTM-2 Comparative Example 2 VTM-1 Comparative Example 3 VTM-2

[0058] S2. Structured film

[0059] (1) Forming: the film is processed into a corrugated structure electret film 12 and a flat structure electret film 11 by a high-temperature corrugated roller 52 and a high-temperature roller 52 rolling forming equipment, respectively, as shown in Figure 3 and Figure 4 The warming area is 160-200℃, and the vehicle speed is 0.5-5 meters / minute.

[0060] (2) Electrification: the formed corrugated structure electret film 12 and flat structure electret film 11 are sent into an electrostatic electrification device through a conveying line, respectively, for electrification, as shown in Figure 10The output voltage of the direct current high voltage power supply for electret is adjustable from 0 to 100 kV; the electret rod for electret is composed of an aluminum alloy square bar 50 and an electret needle 51, the diameter of the electret needle 51 is 0.5-2 mm, the exposed length of the electret needle 51 after being inserted into the aluminum alloy square bar 50 is 10-20 mm, and the spacing is 5-20 mm; the electret rods on the upper surface of the electret film 1 are 4-10, and the spacing is 50-150 mm; the electret rods on the lower surface of the electret film 1 are 4-10, and the spacing is 50-150 mm; the spacing between the static electret needle 51 and the electret film 1 is adjustable, and the adjustment range is 50-150 mm; the vehicle speed is 0.5-5 m / min;

[0061] (3) Cutting: cutting the electret film 12 with corrugated structure and the electret film 11 with flat structure after electret according to the requirements of the product.

[0062] S3. Making a filter

[0063] (1) Stacking: stacking the punched corrugated structure electret film 12 and the flat structure electret film 11 alternately into a tooling jig by using a mechanical hand or manually, as shown in Figure 5 and Figure 6 , to form a stacked electret film 20.

[0064] (2) Bonding: taking out the assembled semi-finished product from the tooling jig and placing it into a hot cutting and bonding device for melting processing (hot melt bonding) and cutting into a filter core semi-product, as shown in Figure 7 and Figure 8 ; the end surface of the corrugated structure electret film 12 and the flat structure electret film 11 in contact is processed to form an overall "arch bridge" shape, maximizing the structural strength; the diameter of the electric heating wire Cr 20 Ni 80 of the hot cutting and bonding device is 0.3-0.6 mm, the working voltage of the electric heating wire is DC 10-24 V, and the hot cutting speed is 30-150 mm / min (corresponding to the stepping motor frequency of 1-5 Hz).

[0065] (3) Cutting: cutting the above prepared filter core semi-product to remove burrs and cutting it into an air filter of the required size, as shown in Figure 1 , Figure 2 and Figure 9 , to obtain a structured electret film 30.

[0066] Process optimization (taking the electret film under the formula of Example 2 as an example):

[0067] ① Effect of electret process on filtration efficiency

[0068] For example, the product with a thickness of 5 mm, the diameter of the electret needle 51 is 0.5 mm, the exposed length is 10 mm, and the interval is 20 mm; the electret rod on the upper surface is 10, and the interval is 150 mm; the electret rod on the lower surface is 10, and the interval is 150 mm; different voltages and electret intervals (equivalent to electric field intensity) are selected for testing:

[0069]

[0070] Note: Electric field intensity E (kV·cm -1 ) = electret voltage / electret interval = U / d

[0071] From the above test data, it can be seen that: different electric field intensities, the filtration efficiency of the prepared sample is quite different, and the electret electric field intensity between 6.0-7.0 kV·cm -1 is most beneficial to the filtration efficiency, and the most preferred working condition is 6.5 kV·cm -1 .

[0072] 2) The influence of the bonding process on the filtration efficiency

[0073] 1) For example, a length of 500 mm, a width of 200 mm, and a thickness of 5 mm, the influence of the processing technology on the filtration efficiency:

[0074]

[0075] Note: Detection instrument: TSI 8130, detection air volume: 32 L / min, detection dust: NaCl@0.3 μm.

[0076] 2) For example, a length of 500 mm, a width of 300 mm, and a thickness of 10 mm, the influence of the processing technology on the filtration efficiency:

[0077]

[0078]

[0079] Note: Detection instrument: TSI 8130, detection air volume: 32 L / min, detection dust: NaCl@0.3 μm.

[0080] 3) For example, a length of 500 mm, a width of 300 mm, and a thickness of 20 mm, the influence of the processing technology on the filtration efficiency:

[0081]

[0082] Note: Detection instrument: TSI 8130, detection air volume: 32 L / min, detection dust: NaCl@0.3 μm.

[0083] From the above test data, it can be seen that under the same electric field intensity, the filtration efficiency of the samples prepared by different bonding processes still has a large difference, and the relatively thin electric heating wire and the relatively low frequency of the stepping motor are more favorable to the filtration efficiency, and most preferably, the diameter of the electric heating wire is 0.3 mm, the frequency of the stepping motor is 2.5 Hz, and the voltage is DC 16-16.5 V.

[0084] The above description of the embodiments is for the purpose of enabling a person of ordinary skill in the art to understand and use the application. It is obvious for those skilled in the art to make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the application should be within the protection scope of the application.

Claims

1. A method for structuring an electret film, characterized in that The electret film comprises the following components in mass percentage: Polypropylene 80-85%; Antibacterial and mildew-proof master batch 5-7%; Flame-retardant master batch 5-8%; Calcium stearate 0.5-2%; Light stabilizer 0.5-1.5%; Antioxidant 1.5-3%; Alpha nucleating agent 0.1-0.5%; Silicon dioxide 0.1-0.5%; The structured processing method comprises the following steps: S1: forming: the electret film is respectively processed into a corrugated structure and a flat structure by a rolling forming device; S2: electretizing: the electret film formed in step S1 is sent into an electrostatic electret device for electretizing; S3: cutting: the electret film after electretizing in step S2 is cut; S4: stacking: the cut electret film in step S3 is alternately stacked according to the corrugated structure and the flat structure to form a stacked electret film; S5: bonding: the stacked electret film obtained in step S4 is placed in a hot cutting and bonding device for melt bonding and slitting to form a filter core semi-finished product; S6: cutting: the filter core semi-finished product obtained in step S5 is cut to obtain an air filter. In step S2, the direct current high voltage power supply is used for the electret; the electret rod for the electret is composed of a fixed strip and a plurality of electret needles, the diameter of the electret needle is 0.5 mm, the exposed length of the electret needle after being inserted into the fixed strip is 10 mm, and the spacing of the electret needles is 20 mm; during the electret process, 10 electret rods are respectively arranged on both sides of the electret film, the spacing between the electret rods is 150 mm; the production line speed of the electret is 3 m / min; and the electret electric field strength is 6.5 kV·cm -1 , the electret electric field strength = electret voltage / electret spacing; The electric heating wire of the hot cutting and bonding device in step S5 is Cr 20 Ni 80 , with a diameter of 0.3 mm and a working voltage of DC 16-16.5 V; the frequency of the stepping motor is 2.5 Hz; the end surface of the corrugated structure of the electret film and the flat structure of the electret film is fused and bonded to form an arch bridge.

2. The method of claim 1, wherein the electret film is structured. The antibacterial and mildew-proof master batch is composed of polypropylene and an antibacterial agent, wherein the antibacterial agent is a composite antibacterial agent with silicate or zeolite as a carrier and silver or zinc loaded thereon.

3. The method of claim 1, wherein the electret film is structured. The flame-retardant master batch is composed of polypropylene and a flame retardant, wherein the flame retardant comprises one or more of phosphorus-nitrogen flame retardants, halogen flame retardants or metal hydroxide flame retardants.

4. The method of claim 1, wherein the electret film is structured. The electret film is processed into a film roll by a flow forming process.

5. The method of claim 1, wherein the electret film is structured. In step S1, the rolling forming device adopts a high-temperature corrugated roller and a high-temperature roller for rolling processing of the corrugated structure and the flat structure, respectively, and the temperature of the warming area is 160-200℃, and the production line speed is 0.5-5m / min.

6. An air filter characterized by, The structured processing method is obtained by using any one of claims 1-5.

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