JP2016534854A - Filter body for dust collection including triple layers - Google Patents

Abstract

The present invention relates to a filter for collecting dust that has excellent dust removal efficiency and excellent durability, and relates to an inorganic fiber support, a fluorine-based resin layer coated with foam on the support, and the foam-coated filter. By including a fluororesin film laminated on the fluororesin layer, it is suitable for collecting fine dust. Adhesion between the inorganic fiber support and the fluororesin film by a foam coating layer of fluororesin The present invention relates to a filter for collecting dust that has excellent power and improved durability.

Description

  The present invention relates to a filter body including a triple layer excellent in durability while effectively removing fine dust.

  Filter dust collectors are most commonly used to remove dust in exhaust gases discharged in the combustion process of industrial bodies. The performance of the filtration dust collector depends on the filtration bag mounted inside. In addition, the type of filtration bag used varies depending on the exhaust gas temperature range, but at a low temperature of about 120 ° C. or less, a Polyester or Polypropylene filtration bag, and at a medium temperature range of 120 to 230 ° C., NOMEX, At higher temperatures such as PPS, P84, or Laminated Membrane Filter, metal filters (˜500 ° C.) and ceramic filters (˜1000 ° C.) are used. In general, combustion takes place in a combustion furnace and the temperature of the exhaust gas exiting through the boiler is in the region of about 500 ° C., and when these again pass through the air preheater, it becomes about 350 ° C. However, since metal filters and ceramic filters are too expensive, the heat is exchanged again at 350 ° C. and the temperature is lowered to around 200 ° C., and then the dust is collected by filtration.

  However, such a system has problems in terms of economy and environment. That is, since the exhaust gas contains dust, these adhere to the surface of the heat exchanger, causing fouling and reducing the heat exchange efficiency. Therefore, it is effective to exchange heat after removing dust at a relatively high temperature. Recently, research is being conducted to increase the heat exchange efficiency by exchanging heat after the dust collector is positioned at the front end of the heat exchanger to remove dust.

  NOMEX, PPS, P84, Laminated Membrane Filter can filter and collect dust at a relatively high temperature in filter media used for medium temperature such as Laminated Membrane Filter, but there are a lot of acidic and alkaline pollutants. When the temperature is 250 ° C. or higher under the existing conditions, there arises a problem that the thin membrane layer disappears. Recently, a filter body that can be used at 250 ° C. or higher by foaming PTFE into a glass fiber fabric using a foam coating process has been developed (Patent Document 1). Since the PTFE layer has a thickness of 100 μm, the filter body has far superior chemical resistance and heat resistance compared to a laminated membrane filter having a membrane layer of 5 μm or less.

  However, the filter body has a pore size of 10 μm or more, and is not so effective for removing fine dust. When dust is removed with high-pressure compressed air, the filter body has a gap between the support body and the foam coating layer. There is a problem that peeling occurs and durability deteriorates. Therefore, it is required to develop a new filter body that solves all these problems, that is, chemical resistance, heat resistance, high performance, and durability.

  Under such a background, the present inventors laminated a thin fluororesin film on the surface of a fluororesin foam coating filter by heat fusion or ultrasonic welding, and formed a filter including a triple layer. By manufacturing, it was confirmed that fine dusts of 10 μm or less could be collected and that a dust collecting filter body with improved durability was provided, and the present invention was completed.

Korean Registered Patent No. 10-0934699

  The objective of this invention is providing the filter body for dust collection excellent in durability while being excellent in the fine dust removal efficiency.

  The present invention includes an inorganic fiber support, a fluororesin layer foam-coated on the support, and a fluororesin film laminated on the foam-coated fluororesin layer. A filter body is provided.

Hereinafter, the configuration of the present invention will be described in detail.
As shown in FIG. 1, the filter for collecting dust according to the present invention includes an inorganic fiber support (1), a fluorine-based resin layer (2) coated with foam on the support, and the foam-coated filter. A fluorine resin film (3) laminated on the fluorine resin layer is included. That is, the dust collection filter of the present invention includes a triple layer.

  The present invention improves the removal efficiency of fine dust by further laminating a fluororesin film on the surface of a fluororesin layer coated with foam on an inorganic fiber support, and improves the efficiency of removing the fine dust. It is characterized by providing a filter body having excellent adhesion between the fiber support and the fluororesin film and improving the durability of the filter body.

In the filter for collecting dust, excellent durability that can prevent the separation phenomenon of the filter due to air pressure applied at the time of dust removal is one of the important characteristics as well as the dust collection efficiency and the dust removal efficiency.
In the present invention, a fluorine resin foam coating layer having a relatively large average pore size is used as an intermediate layer on the inorganic fiber support, and the fluorine resin layer as the intermediate layer is composed of the same type of polymer material. Furthermore, by laminating a fluorine resin film having an average pore size that is small enough to collect fine dust on the uppermost layer, the fine dust removal efficiency is improved and the fluorine resin foam coating is applied. The present invention has been found to provide a filter body with improved durability due to excellent adhesion between the layer and the fluororesin membrane, and the present invention is based on such findings (FIGS. 4 and 8). And FIG. 9).

  As described above, the filter body of the present invention uses a heat resistant material such as an inorganic fiber support and a fluorine resin, and has a multi-layer structure including a triple layer. The resin layer significantly improves the adhesive force between the inorganic fiber support and the laminated fluororesin film, and can be applied not only to dust collection of low temperature exhaust gas having a temperature in the low temperature region, It has an advantage that it can be applied to dust collection of medium / high temperature exhaust gas having a temperature in the medium / high temperature range.

The term “fine dust” used in the present invention means dust having an average particle size of 10 μm or less.
The term “low temperature exhaust gas” used in the present invention means an exhaust gas having a temperature in a low temperature region having a temperature of 120 ° C. or less.

  The term “medium / high temperature exhaust gas” used in the present invention has a temperature in the middle / high temperature region having a temperature of 120-500 ° C., preferably 150-300 ° C., more preferably 200-300 ° C. It means exhaust gas.

The term “inorganic fiber support” used in the present invention means an inorganic fibrous support having heat resistance and chemical resistance suitable for a filter for collecting dust from combustion exhaust gas.
As the inorganic fiber support used in the present invention, one selected from the group consisting of glass fiber, alumina fiber and silica fiber can be used, but is not limited thereto. In one embodiment of the present invention, glass fiber was used.

The said inorganic fiber support body may acquire and use what is marketed, and may be directly manufactured and used for it.
400-1000 micrometers may be sufficient as the thickness of the said inorganic fiber support body in this invention.

  The term “fluoropolymer” used in the present invention means a synthetic resin containing fluorine atoms in the molecule. Fluorine-based resins are extremely excellent in heat resistance, chemical resistance, low temperature resistance, electrical insulation, high frequency characteristics, etc., and also have unique non-adhesiveness and low friction characteristics. In the present invention, it is possible to provide a filter suitable for use in dust collection of medium / high temperature exhaust gas, particularly due to the excellent heat resistance of the fluororesin.

  In the present invention, the fluororesin includes polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyhexa Fluoropropylene (PHFP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer It may be selected from the group consisting of (EPE) and tetrafluoroethylene-ethylene copolymer (ETFE), but is not limited thereto. In one embodiment of the present invention, polytetrafluoroethylene (PTFE) was used as the fluorine-based resin.

  The term “polytetrafluoroethylene (PTFE)” used in the present invention means a fluororesin containing a fluorine compound represented by the following general formula 1 in which all hydrogen of polyethylene is changed to fluorine. . PTFE is known under the trade name Teflon (registered trademark), has the highest operating temperature (290 ° C / 550 ° F) among fluororesins, and is resistant to almost all chemicals. And having a smooth surface.

In the said General formula 1, n is an integer of 100-10,000.

  The term “foam coating layer of fluororesin” used in the present invention means a layer formed by foam coating a coating liquid containing a fluororesin that is a heat-resistant resin on the inorganic fiber support. To do.

  The fluorine-based resin layer coated with foam in the filter for collecting dust of the present invention has an average pore size much larger than that of the fluorine-based resin film laminated on the upper part, and maintains a low pressure loss. Plays a role in increasing dust removal efficiency. The foam coating layer of the fluororesin serves as an adhesive for strengthening the bond between the lower inorganic fiber support and the upper fluororesin film, resulting in the durability of the filter body. Can be improved.

  In the present invention, the average pore size of the fluororesin layer to be foam-coated is not limited as long as it is larger than the average pore size of the laminated fluororesin film, but is preferably 100 μm or less, more preferably 30 μm or less, Preferably, it may be 10 μm to 30 μm. The foam coating layer of the fluororesin can serve as a support when dust is dropped from the dust collection filter with compressed air, and it is desirable that the pores be as large as possible.

  In the present invention, the fluororesin foam coating layer may be formed by foam coating, preferably using a coating liquid containing a fluororesin, a foam stabilizer, a foaming agent and a thickener. Good.

  The term “foam stabilizer” as used in the present invention means a substance that acts as a resin foam maintenance agent. In the present invention, the foam stabilizer may be selected from the group consisting of hydroxyethyl cellulose, carboxymethyl cellulose and ammonium stearate, and is not limited thereto.

  The term “foaming agent” used in the present invention means a substance that creates bubbles of a resin coating solution. In the present invention, as the foaming agent, an anionic foaming agent containing sodium laurate or sodium stearate or a nonionic foaming agent containing a polyethylene glycol type or a polyhydric alcohol type is used. Can be, but is not limited to them.

  The term “thickening agent” used in the present invention means a substance that acts to maintain a state in which resin foam adheres to fibers. In the present invention, the thickener may be an acrylic thickener and is not limited thereto.

  In the present invention, the coating liquid may be first processed with a foam generator to create foam, and then applied to the surface of the inorganic fiber support to form a cellular fluorine-based resin layer.

Thereafter, the support on which the foam is applied can be dried to form a dried foam-like fluororesin layer.
In the present invention, the support on which the foam is applied can be dried in two steps by primary drying and secondary drying. A stable microporous surface layer is formed in such primary and secondary drying processes.

In the present invention, preferably, in the drying of the support on which the foam is applied, primary drying can be performed at 80 ° C. to 120 ° C., and secondary drying can be performed at 180 ° C. to 220 ° C.
Thereafter, the dried support can be pressure-bonded to increase the strength of the fine porous fluororesin layer and to smooth the surface. Such a crimping process can be performed as necessary, and is not an indispensable process.

In the present invention, the pressure-bonding treatment of the dried support is preferably performed at a pressure of 200 psi to 700 psi.
Then, the surface layer excellent in surface strength can be formed by heat-treating and curing the support subjected to the pressure-bonding treatment.

In the present invention, the heat treatment is preferably carried out at 340 ° C. to 400 ° C. for curing.
Thereafter, the heat-treated support is cooled to obtain a fluorine resin layer that is primarily foam-coated.

As described above, a filter having a double layer structure can be obtained by first foam-coating the fluororesin layer on the surface of the inorganic fiber support.
The double layer structure filter body having the fluorine resin layer coated with foam on the surface of the inorganic fiber support as described above has a thickness of the fluorine resin layer in the range of 50 to 150 μm, particularly about 100 μm. Compared with a laminated membrane filter having a membrane layer of 5 μm or less, it exhibits extremely excellent chemical resistance and heat resistance. However, the filter body has an average pore size of 10 μm or more and about 10 μm to 30 μm, and is not very effective for removing ultrafine dust of 2.5 μm or less.

Accordingly, the present invention is characterized in that a fluorine resin film is further laminated on the surface of the fluororesin foam coating filter.
That is, the present invention provides a filter body in which a fluorine-based resin film is secondarily laminated on the above-obtained primarily foam-coated fluorine-based resin layer.

  Preferably, in the present invention, a filter body having a total triple layer structure including an inorganic fiber support layer obtained by secondarily laminating a fluorine-based resin film thinner than this on the surface of the foam-coated fluorine-based resin layer. Can be manufactured.

  In the present invention, when the lamination is performed, the lower foam-coated fluorine-based resin layer and the upper fluorine-based resin film are composed of the same type of polymer material and have excellent adhesion between them. Glued.

In the present invention, the thickness of the foam-coated fluororesin layer may be preferably 5 to 100 μm.
In the present invention, the laminated fluororesin film may preferably have a thickness of 1 to 50 μm.

  In the present invention, the laminated fluororesin film may have a porous web structure made of fluororesin fibers. Through such a porous web structure, the filter body of the present invention can also collect fine dust.

  In the present invention, the fluororesin film is a process of producing a fluororesin film by extruding a mixture containing a fluororesin powder and a lubricant (process 1), and a process of biaxially stretching the fluororesin film ( It can be manufactured by a manufacturing method including step 2).

In the present invention, the mixing ratio of the fluororesin powder and the lubricant may be 9: 1 to 7: 1 on a weight basis.
In the present invention, the lubricant may be an isoparaffinic compound. Specifically, ISOPAR M (Exxon Mobile, USA) can be used as the lubricant.

In the present invention, the biaxial stretching can be performed by first performing primary stretching in the vertical axis direction and then secondary stretching in the horizontal axis direction.
As a preferred embodiment, a PTFE film can be used as the fluorine resin film. PTFE membrane is a mixture of PTFE powder (F104, Daikin, Japan) and lubricant (ISOPAR M, Exxon Mobile, USA) in a ratio of 9: 1 to 7: 1 and extruded at high pressure in a paste state. Then, after a PTFE film is formed by calendering, the film is first stretched in the vertical axis direction and secondarily stretched in the horizontal axis direction.

  In the present invention, the thickness of the fluororesin film to be extruded to adjust the thickness of the fluororesin film is 50 to 500 μm, and then by primary stretching in the vertical axis direction and secondary stretching in the horizontal axis direction, The thickness is reduced to 1/3 to 1/10. Therefore, the thickness of the fluororesin film is finally about 1 to 50 μm.

In the present invention, the pore size of the fluororesin film can be determined by the thickness of the fluororesin film and the diameter and filling rate of a single fiber in the fluororesin web.
In the present invention, the average pore size of the laminated fluororesin film is preferably 10 μm or less, more preferably 2.5 μm or less, and further preferably 0.1 μm to 2.5 μm.

  In the present invention, the diameter of the fluororesin fiber may be preferably 0.01 to 1 μm. If the diameter of the fluororesin fiber is smaller than the lower limit with the same fluororesin filling ratio, the removal efficiency of ultra fine dust is increased, and if the diameter of the fluororesin fiber exceeds the upper limit, the dust collection efficiency is increased. Lower. However, the pressure loss has a property that is inversely proportional to the fiber diameter. On the other hand, when it is stretched with the same amount of the fluororesin, the diameter of the fluororesin fiber becomes smaller as it is stretched. In the case of the filter made in this manner, the diameter of the fluororesin fiber is smaller than the lower limit, the pores of the porous web are too large, and the removal efficiency of ultrafine dust is reduced. If the diameter exceeds the upper limit, the pores of the porous web are too small and the filter body may be clogged with dust collected.

In the present invention, the laminating can be performed by heat fusion or ultrasonic welding.
The filter body according to an embodiment of the present invention is superior in heat resistance compared to existing filter bodies, is resistant to heat shrinkage, has a dust particle diameter of 1 μm or more, and a partial dust collection efficiency based on a number concentration of 98% or more. It shows a mass dust collection efficiency of 8% or more and an excellent dust removal efficiency. Further, pores having an average pore size of 100 μm or less are uniformly distributed in the foam-coated fluororesin layer, and pores having an average pore size of 10 μm or less are uniformly distributed in the laminated PTFE membrane. . Therefore, the filter body according to the present invention is suitable for collecting fine dust of 10 μm or less, and is sufficiently applicable to the treatment of exhaust gas in the middle / high temperature region.

Moreover, the filter body according to the present invention is superior in durability as compared with existing single-layer or double-layer filter bodies. In one experimental example of the present invention, after a PTFE membrane is laminated on the surface of a glass fiber fabric or glass fiber fabric coated with foam to produce a triple layer or double layer filter body, respectively, a high pressure is applied to the respective filter bodies. As a result of injecting compressed air ( ² , 3, 4, 5 kgf / cm ² ) and evaluating the degree of peeling, the membrane layer of the double layer filter was peeled from 3 kgf / cm ² (FIGS. 6 and 7). ) It was confirmed that the triple layer filter body did not peel even in the high pressure injection of 5 kgf / cm ² (FIGS. 8 and 9).

  In the present invention, the surface of the inorganic fiber support is firstly foam-coated with a fluorine resin layer, and a thin fluorine resin film is formed on the surface of the foam-coated fluorine resin layer by heat fusion or ultrasonic welding. By laminating and producing a filter body including a triple layer, there is an effect of providing a filter for collecting dust that not only exhibits chemical resistance and heat resistance but also can collect fine dust of 10 μm or less. is there. Moreover, the filter body of this invention is excellent in the adhesive force between an inorganic fiber support body and a fluororesin film | membrane by the foam coating layer of a fluororesin, and can also improve durability.

It is the figure which showed simply the triple layer structure of the filter body for dust collection of this invention. It is the result of having magnified 300 times with the electron microscope and observing the surface of the filter body which concerns on this invention. It is a pore distribution measurement result of the filter body which concerns on this invention. It is a measurement result of the partial dust collection efficiency of the filter body concerning the present invention. It is a contact angle measurement result which shows the dust removal characteristic of the filter body which concerns on this invention, and the filter body of the comparative example 1. It is a peeling degree measurement result evaluated by visual inspection after injecting high-pressure compressed air to the filter of comparative example 1. It is a peeling degree measurement result evaluated by the stereomicroscopic analysis after injecting high-pressure compressed air into the filter body of Comparative Example 1. It is a peeling degree measurement result evaluated by visual inspection after injecting high-pressure compressed air to the filter body of Example 1. It is a peeling degree measurement result evaluated by the stereomicroscopic analysis after injecting high-pressure compressed air into the filter body of Example 1.

  Hereinafter, the present invention will be described in more detail with reference to examples. These examples are merely for explaining the present invention more specifically, and the scope of the present invention is not limited by these examples.

Example 1: Production of a triple layer filter of the present invention A PTFE membrane is laminated on the surface of a foam coated filter (GL-TEX-790, Chang Myung Sangyo Co., Ltd., Korea) as follows to form a triple layer structure. The filter body was completed.

In order to manufacture a PTFE membrane, first, PTFE powder (F104, Daikin, Japan) and a lubricant (ISOPA M, Exxon Mobile, USA) were mixed at a ratio of 8: 1, and a PTFE raw material in a paste form was mixed with an extruder. Manufactured. The PTFE raw material thus produced was passed through a calendering roll maintained at a high temperature of 350 ° C. and a constant tension to produce a PTFE film. The PTFE film was stretched in the vertical and horizontal directions to produce a PTFE film having a thickness of about 5 μm. A glass fiber fabric (GL-TEX-790) coated with foam and a PTFE membrane are rewound by two winders (UNWINDER) and supplied together to a calendering roll and pressure-bonded at a pressure of 4 kgf / cm ^2. A filter body having a triple layer structure was prepared. The working speed at that time was 12 m / min.

Comparative Example 1: Manufacture of double layer filter body Except immediately laminating a PTFE membrane on the surface of glass fiber fabric (General Electric, US) instead of foam coated glass fiber fabric (GL-TEX-790) Completed the double layer filter in the same manner as in Example 1.

Experimental Example 1: Surface and cross-sectional property test In order to confirm the surface and cross-sectional properties of the filter body according to the present invention, the surface of the filter body produced in Example 1 was observed by magnifying it 300 times with an electron microscope.

The result of observing the surface of the filter body according to the present invention at 300 times magnification with an electron microscope is shown in FIG.
As shown in FIG. 2, it was confirmed that the PTFE web formed by lamination on the surface of the filter body according to the present invention was uniformly distributed on the pores formed by the foam coating.

Moreover, the result of the pore size distribution measurement with respect to the filter is shown in FIG.
As can be seen from the measurement results in FIG. 3, the average pore size is 1.3 μm, which is 1/10 of the average pore size of the foam coating filter 13 μm. From the result, it can be seen that the filter body completed according to the present invention can effectively remove fine dust of 2.5 μm or less.

Experimental Example 2: Analysis of Dust Collection Efficiency In order to analyze the dust collection efficiency of the filter body according to the present invention manufactured in Example 1, the following experiment was performed.

  The filter body according to the present invention is for collecting dust contained in the combustion gas generated from a coal-fired power plant, and fly ash generated from the coal-fired power plant is used for performance evaluation of the filter body. It was. For this experiment, the gas temperature was first set at 250 ± 10 ° C., and the test dust used showed a geometric mean particle size of 2 μm and a geometric standard deviation of 1.5. The particle size distribution of the test dust was measured by the particle counter (APS 3321, TSI Inc.) at the number concentration at the front and rear ends of the filtration bag attached to the filtration dust collector. The mass dust collection efficiency of the filter body was obtained by converting the mass concentration from the size and number concentration of the dust.

  FIG. 4 shows the dust collection efficiency based on the number concentration of the filter according to the present invention, and Table 1 shows the mass dust collection efficiency of the filter according to the present invention.

As shown in FIG. 4, the filter body according to the present invention exhibited a dust collection efficiency based on a number concentration of 98% or more with a dust particle diameter of 1 μm or more. The filter body according to the present invention has the characteristics of a typical dust collection filter body that exhibits a higher dust collection efficiency as the particle size decreases as the particle size decreases.

  Moreover, as Table 1 showed, the mass dust collection efficiency of the filter body which concerns on this invention showed very high dust collection efficiency with 99.8%. This indicates the dust collection efficiency in the initial state of filtration. Therefore, based on the filtration theory that the dust collection efficiency is increased by collecting the dust, the dust collection of 99.9% or more within a very short time. It can be seen that it shows efficiency.

Experimental Example 3: Analysis of Contact Angle for Predicting Dedusting Efficiency In order to predict the dedusting efficiency of the filter body according to the present invention, the following experiment was performed.
Using the filter produced in Example 1, the contact angle was measured. For the measurement, a contact angle measuring device (DSA100, Kruss) was used. The results are shown in FIG.

  As FIG. 5 shows, the contact angle of the filter body which concerns on this invention is 143 degree | times, and it turns out that the value 10 degree higher than the contact angle 133 degree | times of GL-TEX-790 which is a regular filter body is shown. The result means that the dust removal efficiency of the filter body completed by the present invention is more excellent.

Experimental Example 4: Durability Test For comparison of durability between the triple layer filter of the present invention produced in Example 1 and the double layer filter produced in Comparative Example 1, a peel degree comparison experiment was performed. .

First, high pressure compressed air ( ^{2, 3, 4, 5} kgf / cm ² ) is jetted onto the surface of each membrane of the filter body to evaluate the degree of peeling, and jetting of compressed air is performed at intervals of 1 second. Goed to the times.

  FIG. 6 and FIG. 7 show the measurement results of the degree of peeling evaluated by visual inspection and stereomicroscopic analysis after injecting high-pressure compressed air onto the filter body of Comparative Example 1 as described above.

Moreover, after injecting high-pressure compressed air into the filter body of Example 1, the peel degree measurement results evaluated by visual inspection and stereomicroscopic analysis are shown in FIGS. 8 and 9, respectively.
6 to 9, the membrane layer of the double layer filter of Comparative Example 1 is peeled from 3 kgf / cm ² (FIGS. 6 and 7), but the triple layer filter of Example 1 is 5 kgf / cm. It can be confirmed that no peeling occurs in the high-pressure jet No. ² (FIGS. 8 and 9). Therefore, it can be seen that a strong bonding force acts between the foam-coated PTFE layer and the laminated PTFE membrane, thereby improving the durability of the filter body.

Claims (17)

Inorganic fiber support,
A filter for collecting dust, comprising: a fluororesin layer coated with foam on the support; and a fluororesin film laminated on the fluororesin layer coated with foam.   The filter body according to claim 1, wherein the filter body is for dust collection of medium / high temperature exhaust gas.   The filter for collecting dust according to claim 1, wherein the inorganic fiber support is selected from the group consisting of glass fiber, alumina fiber and silica fiber.   The filter body for dust collection according to claim 1, wherein the inorganic fiber support has a thickness of 400 to 1000 µm.   The fluororesin includes polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyhexafluoropropylene (PHFP). ), Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE) and The filter body for dust collection according to claim 1, wherein the filter body is selected from the group consisting of tetrafluoroethylene-ethylene copolymer (ETFE).   The filter body for dust collection according to claim 1, wherein an average pore size of the fluorine-based resin layer to be foam-coated is 100 µm or less.   The dust collection according to claim 1, wherein the fluororesin layer is formed by foam coating using a coating liquid containing a fluororesin, a foam stabilizer, a foaming agent, and a thickener. Filter body.   The filter for collecting dust according to claim 7, wherein the thickener is an acrylic thickener.   The filter body for dust collection according to claim 1, wherein the foam-coated fluorine-based resin layer has a thickness of 5 to 100 µm.   The filter body for dust collection according to claim 1, wherein the laminated fluororesin film has a thickness of 1 to 50 μm.   The filter for collecting dust according to claim 1, wherein the laminated fluororesin film has a porous web structure made of fluororesin fibers.   The laminated fluororesin film includes a step of producing a fluororesin film by extruding a mixture containing a fluororesin powder and a lubricant (step 1) and a step of biaxially stretching the fluororesin film ( The filter body for dust collection according to claim 1, which is manufactured by a manufacturing method including step 2).   The filter body for dust collection according to claim 12, wherein a mixing ratio of the fluororesin powder and the lubricant is 9: 1 to 7: 1 on a weight basis.   The filter for collecting dust according to claim 12, wherein the lubricant is an isoparaffinic compound.   The filter body for dust collection according to claim 1, wherein an average pore size of the laminated fluororesin film is 10 µm or less.   The filter body for dust collection according to claim 11, wherein the diameter of one fluorine resin fiber is 0.01 to 1 μm.   The filter for collecting dust according to claim 1, wherein the laminating is performed by heat fusion or ultrasonic welding.