JP4868512B2 - Airborne particulate collection device - Google Patents

Description

  The present invention relates to a suspended particulate collection device that captures suspended particulates such as pollen, yellow sand, and asbestos floating in the atmosphere.

In recent years, trace amounts of suspended particulates, sea salt particles, yellow sand, gaseous chemicals that cause air pollution such as carbon dioxide, NOx, SOx, volatile chemicals such as formaldehyde that cause sick house syndrome, Solid or fibrous suspended particulates such as metal oxides, pollen, dust, diesel exhaust particulates, asbestos, etc. are regarded as important substances affecting human health and affecting the environment, and are suspended in the atmosphere. Development of technology for analyzing the size and shape of fine particles or chemical substances contained in the particles is underway.
As an analysis method for suspended particulates, a method has been developed in which suspended particulates in an atmosphere such as the air are once collected on a filter or the like and each collected particulate is analyzed.
As such a technique, for example, there is a technique described in Patent Document 1 developed by the present inventors. (Patent Document 1) states that “a predetermined region of a band-shaped fine particle collector disposed in a housing having an opening is exposed to a gas containing floating fine particles for a predetermined time to collect floating fine particles, There is a suspended particle analysis method for capturing a predetermined area and processing the captured image to measure the shape, size, property, or relative position or distance between the suspended particles, and a particle collecting apparatus used therefor ” It is disclosed. In (Patent Document 1), as a fine particle collector for collecting fine particles, a film made of synthetic resin such as polystyrene, polybutadiene, polyethylene or the like, or a fiber shape such as a glass fiber filter, a quartz fiber filter, or a fluororesin filter is used. The use of filters is described.

However, the technique disclosed in (Patent Document 1) has the following problems.
(1) When fine particles are collected, depending on the type of the collected floating fine particles, the fine particles may react with each other, resulting in a compound that is different from the floating state in the atmosphere. There was a problem that I could not.
(2) It is necessary to use a large and expensive analyzer. Therefore, it is difficult to analyze airborne particles in the atmosphere easily and quickly at the site where airborne particles are collected. There was a problem that it was difficult to obtain environmental data related to suspended particulates.
(3) When fine particles are collected by a fiber filter such as a glass fiber filter, a quartz fiber filter, or a fluororesin filter, the fine particles enter the gaps between the filter fibers. When analyzing, it is difficult to separate and analyze the filter fibers and fine particles, and the aggregation of the fine particles is promoted in the narrow gap between the filter fibers, so that it is difficult to separate and analyze the fine particles at the time of analysis. there were.

Therefore, the present inventors have completed the technique described in (Patent Document 2) in order to solve the above problem. (Patent Document 2) states that “a filter for collecting floating particles having a large number of holes having a hole diameter of 20 μm or less, a thickness of 0.1 to 20 μm, and an open area ratio of 45 to 75%; A housing in which the filter for collecting suspended particulates is disposed so that a predetermined region of the filter for use is exposed from the opening, and the suspended particulates that are respectively rotatably disposed facing the interior of the housing. A filter feed section having a pair of support shafts around which both ends of the collection filter are wound, and sending out a new predetermined area of the suspended particulate collection filter to the opening by rotating the support shaft And a suspended particulate collection device comprising:
With the technology disclosed in (Patent Document 2), suspended particulates can be collected continuously easily and quickly at an indoor or outdoor site, and suspended particulates can be collected in each hole of the suspended particulate collection filter. Since it can be collected separately and collected in a separated state, the collected fine particles are difficult to react with each other and can be accurately analyzed, and furthermore, the suspended fine particles can be collected on the surface of the porous membrane, It was possible to easily perform image analysis by capturing images while collecting the fine particles, and to enable rapid analysis.
JP 2004-301768 A JP 2005-152849 A

However, the invention described in (Patent Document 2) has room for improvement in the following points.
(1) The suspended particulate collection device disclosed in (Patent Document 2) has a pair of support shafts around which both ends of the suspended particulate collection filter are wound, and is opened by rotating the support shaft. Since a new predetermined region of the suspended particulate collection filter is sent out to the part for measurement, when the suspended particulate collection filter is delivered, the porous film may extend in the delivery direction and the hole may be deformed. When the hole is deformed, the pore size changes, the effect of airborne particle classification is reduced, and the accuracy of analysis of the shape and particle size of the airborne particles is lacking. There was a need for a device that could collect them automatically.
(2) If the porous membrane extends in the delivery direction when the suspended particulate collection filter is sent out and the hole is deformed, the analysis of the shape and particle size of the suspended particulates is inaccurate. The strength is required so that the film does not stretch. For this reason, the structure and manufacturing process of the suspended particulate collection filter, such as reinforcing the porous membrane, become complicated and the productivity is lowered, so an apparatus that can use a simple suspended particulate collection filter is required. It was.
(3) Since both ends of the filter for collecting suspended particulates have a pair of support shafts wound respectively, the configuration tends to be complicated and the apparatus tends to be large. Therefore, there has been a demand for an apparatus that has a simple configuration and can be miniaturized.
(4) Sending out the filter for collecting suspended particulates can collect suspended particulates in time series, and at the same time, simple analysis by image analysis is possible, but for performing precise analysis by optical microscope, electron microscope, etc. However, it was necessary to unwind the wound particulate collection filter and cut out the corresponding part, which was an obstacle to rapid analysis work after collection. Therefore, there has been a demand for an apparatus that can be taken out immediately after collection and can be analyzed as it is.

  The present invention satisfies the above-mentioned requirements. Since the pores of the porous membrane of the filter are not easily deformed, the shape and particle size of the collected suspended fine particles can be accurately analyzed, and the analysis accuracy is excellent. The structure and manufacturing process can be simplified, the filter productivity is excellent, the filter pressure loss is small, and it is hard to clog, so the suction means is downsized by reducing the inner diameter of the air passage Therefore, the device configuration can be simplified, the device can be reduced in size and weight, it can be carried indoors and outdoors, and it is highly portable. An object of the present invention is to provide a suspended particulate collection device capable of analysis.

In order to solve the above conventional problems, the suspended particulate collection device of the present invention has the following configuration.
The suspended particulate collection device according to claim 1 of the present invention is a suspended particulate collection device that collects suspended particulates using a filter in which a porous film is held by a holder, and is used for loading the filter. A housing having a plurality of openings, an air passage penetrating into the housing and having an air inlet at one end and an air outlet at the other end, and disposed in the housing and inserted from the opening. A filter mounting portion in which one or a plurality of the filters are detachably mounted and the porous membrane is disposed in the air path; and suction means disposed in the air path; and the air path includes : An upstream air passage in which the intake port is formed at one end and a downstream air passage in which the exhaust port is formed at an end, and the filter mounting portion includes the upstream air passage and the downstream air passage. A first support part formed between the road and fixed to the housing; and the first support part A first support portion through-hole in which a female screw portion is threaded on the inner peripheral surface, a second support portion disposed at a distance from the first support portion, and penetrating the second support portion A second support portion through hole communicating with the first support portion through hole, and screwed into the outer peripheral surface of the upstream air passage with the screw portion of the inner peripheral surface of the first support portion through hole. And a male screw portion is formed as a holding means for bringing the holder of the filter into close contact with the end surfaces of the upstream and downstream air passages, and the downstream air passage is formed in the second support portion through-hole. It has a connected configuration.
With this configuration, the following effects can be obtained.
(1) Since a filter having a holder holding a porous film and a filter mounting part for detachably mounting the filter in the air passage and disposing the porous film in the air passage are collected, suspended particulates are collected. By removing the filter from the filter mounting part and mounting a new filter, it is possible to replace the filter without applying external force such as tensile force to the porous film of the filter. The shape and particle size of the fine particles can be analyzed accurately.
(2) Since the filter in which the porous film is held by the holder is used, the configuration and manufacturing process of the filter can be simplified, and the productivity of the filter is excellent.
(3) Reduce the inner diameter of the air passage by reducing the pressure loss of the filter and the high collection efficiency of suspended particulates, and in addition, since most of the particles below the pore size of the porous membrane permeate, it is difficult to clog. Therefore, the suction means can be reduced in size, so that the configuration of the apparatus can be simplified, the apparatus can be reduced in size and weight, and can be carried indoors and outdoors, and is excellent in portability.
(4) Since the filter can be made small and can be easily desorbed even if the filters are stacked in multiple stages, suspended particulates can be taken out immediately after collection and used as it is as a sample in an analytical instrument, allowing rapid analysis at the collection site. Enable.
(5) A plurality of filters with different hole diameters are stacked, and the pore diameter of the porous membrane of the filter mounted on the downstream side of the air passage is set to be larger than the pore diameter of the porous membrane of the filter attached on the upstream side of the air passage. By reducing the size, suspended microparticles with different particle sizes can be collected in each porous membrane, so that multi-stage classification can be performed, particle size distribution can be measured, and suspended particles of a specific size can be measured. Sorted and collected.
(6) Since the filter mounting part is provided with a holding means for bringing the filter holder into close contact with the upstream air passage and the end face of the downstream air passage, the sucked gas leaks from between the holder and the air passage. This improves the quantitativeness of the gas flow rate and the amount of suspended particulates collected. For this reason, the amount of gas that has passed through the porous membrane can be calculated based on the suction flow rate and suction time of the gas per unit time, and it depends on the suspended particulates at the collection site from this amount of gas and the number and type of collected suspended particulates. The degree of contamination can be measured.
(7) Since the holding means is formed to be movable according to the number of filters attached to the filter attachment portion, a plurality of filters can be attached to the filter attachment portion in an overlapping manner.
(8) Since the upstream side air passage can be moved forward or backward by the male screw portion as the holding means, a desired number of filters can be mounted on the filter mounting portion, and the flexibility is excellent.

Here, as the porous film, for example, one formed of a polymer compound is used. Examples of such a polymer compound include fluorine-based polymers such as polyvinylidene fluoride and trifluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyetherimide, polyethylene terephthalate, polymethyl methacrylate, polybutyl (meth) acrylate, and other polymers. Cellulose esters such as (meth) acrylic acid ester, polyacrylonitrile, cellulose acetate, cellulose nitrate, polyolefins such as polyethylene, poly-4-methyl-1-pentene, polybutadiene, polylactic acid, polyhydroxybutyric acid, glycolic acid-lactic acid Biodegradable polymers such as copolymers, polyvinyl acetate, polystyrene, poly-4-vinylpyridine, polyvinylpyrrolidone, polyvinyl chloride, polyvinylidene chloride, silicon-based polymers, polyphenyl Polymers such as down-oxide, or can be exemplified a copolymer thereof.
The porous film can be produced by a wet coagulation method or a combination of a wet coagulation method and a charged particle irradiation method. It can also be produced by the steam coagulation method described in JP-A-63-267406.
Further, as described in JP-A-2005-152849, a solution in which the above-described polymer compound is dissolved in a hydrophobic organic solvent is cast on a substrate, and high-humidity air is blown to the hydrophobic organic solvent. It can also be produced by evaporation. Examples of such hydrophobic organic solvents include aromatic hydrocarbons such as benzene, toluene, and p-xylene, halogenated aromatic hydrocarbons such as monochlorobenzene, o-dichlorobenzene, and trichlorobenzene, chloroform, carbon tetrachloride, and chloride. Halogenated aliphatic hydrocarbons such as methylene, trichlorethylene, and perchloroethylene, and aliphatic hydrocarbons such as pentane, hexane, heptane, and octane. In addition, what melt | dissolved the amphiphilic polymer compound with the polymer compound in the hydrophobic organic solvent can also be used. As a mixing ratio of the polymer compound and the amphiphilic polymer compound, a weight ratio of 5: 1 to 20: 1 is used. As the amphiphilic polymer compound, amphiphilic polyacrylamide or the like is used.
The porous film formed of the polymer compound in this way has the characteristics that the network-like polymer portion is extremely thin and has a very large opening, and the polymer is also nearly transparent. The suspended fine particles thus obtained can be observed with transmitted light without pretreatment with an optical microscope, which is excellent in convenience. Conventionally, when counting analysis of suspended particulates collected on a white membrane filter, if the suspended particulates are transparent particulates such as asbestos, it is necessary to perform a transparent treatment of the membrane filter using acetone or the like. It was complicated.

As the shape of the hole of the porous film, a circle or an ellipse is used. Among these, a hole formed in a circular shape is preferably used. This is because the classification effect is excellent.
As a hole diameter of the hole part of a porous membrane, it can set suitably in the range of 0.1-20 micrometers, preferably 0.1-10 micrometers. The target of collection is sea salt particles, yellow sand, metal oxides, pollen and other allergen materials, dust, diesel exhaust particles, asbestos, toner and other artificial materials, bacteria and other solid and fibrous suspended particles. These particle size distributions (in the case of fibrous suspended fine particles, have a short diameter distribution) have a peak in the vicinity of 7 μm and 3 μm or less, and can be suitably used for collecting these particles.
The thickness of the porous film is preferably from 0.1 to 20 μm. As the thickness becomes thinner than 0.1 μm, the strength of the porous membrane decreases and the durability decreases. As the thickness becomes thicker than 20 μm, it becomes difficult to form a hole having the same shape and diameter, and the productivity of the porous membrane is reduced. Since it falls, neither is preferable.
As the porosity of the porous film, 45 to 75% is used. As the porosity of the porous membrane becomes smaller than 45%, suspended fine particles having a particle size smaller than the pore diameter tend to get caught or clogged. As the porous membrane becomes larger than 75%, the strength of the porous membrane decreases. However, since there is a tendency for the durability to decrease, neither is preferable.

  As the holder, a holder made of metal, synthetic resin, rubber, glass, ceramic or the like can be used.

As the filter mounting portion, any porous membrane can be used without particular limitation as long as the porous membrane can be disposed in the air passage and the filter can be detachably mounted. The end face or cross section of the air passage is in close contact with the filter holder, and a porous film is disposed at the intake or exhaust port, or a porous film is disposed between the intake and exhaust ports. Used. This is for allowing the gas sucked by the suction means to pass through the porous film without leakage.
One or a plurality of filters can be mounted on the filter mounting portion. A glass fiber filter, a quartz fiber filter, or a membrane filter can also be mounted on the downstream side of the filter provided with the porous membrane. Thereby, the fine suspended fine particles which passed the porous film can be collected.

A suction pump is used as the suction means. Moreover, what makes a convection generate | occur | produce with a heater etc. and attracts | sucks gas from an inlet port can also be used. The suction means may be arranged on either the upstream side or the downstream side of the air passage of the arranged porous membrane.
In addition, by appropriately setting the suction flow rate and suction time of the gas per unit time by the suction means, the amount of sucked gas, that is, the amount of gas that has passed through the porous film can be calculated. It is possible to measure the degree of contamination by suspended fine particles at the collection site from the number and type of the particles.

Standard deviation of the hole is 0.5μm or less, or if the variation coefficient of the hole is 0.2 or less, since the considerably narrow pore size distribution, it is possible to increase the classification effects in the porous membrane, asbestos, etc. The collection efficiency in the case of collecting fibrous suspended fine particles can be increased.
Moreover, since the pore size distribution is extremely narrow, it is possible to collect fine particles having a uniform particle size, for example, to selectively collect cedar pollen and yellow sand.

  Here, the standard deviation of the hole is preferably 0 to 0.5 μm, and the coefficient of variation is preferably 0 to 0.2. The coefficient of variation is a numerical value obtained by dividing the standard deviation by the average. As the standard deviation is larger than 0.5 μm or the coefficient of variation is larger than 0.2, the pore size distribution is widened, so that the classification effect is lowered, and the fiber length of fibrous suspended fine particles such as asbestos is reduced. Neither of these is preferred because it tends to be difficult to be collected through the hole.

  As a method for producing a porous membrane for reducing the standard deviation and coefficient of variation of the pores, a method is used in which polystyrene spheres having the same particle diameter are used as a mold, and finally the polystyrene spheres are removed by pyrolysis or solvent ( Chem. Mater. 2005, 17 (24), p5880-5883) or a method of forming a through-hole in a thin film of metal, semiconductor, or ceramic by a semiconductor fine processing technique. Moreover, when forming a porous film with a polymer compound, the standard deviation and variation coefficient of the pores can be reduced by optimizing the manufacturing conditions such as temperature.

Filter comprising a pierced by through holes in the thickness direction of the holder, when the porous membrane is disposed in the through hole, by reducing the inner diameter of the through hole, the porous when the porous membrane is the gas passes The deformation of the membrane can be reduced, the pores can be prevented from being deformed or expanded, and the effect of classifying the suspended particles in the porous membrane can be enhanced. The collection efficiency in the case of collecting can be improved.
In addition, since the strength of the porous film disposed in the through hole can be ensured, the porous film can withstand the passage of gas at a high flow rate, so that the gas suction speed can be increased and the gas suction time per unit volume Can be shortened.

  Here, 5-10 mm is used suitably as an internal diameter of a through-hole. As the inner diameter of the through-hole becomes smaller than 5 mm, the trapped fine particles tend to be clogged due to the trapping area of the porous membrane being reduced, and the porous membrane tends to clog. The deformation of the porous membrane becomes large when passing through, and the pores are deformed or spread, and the classification effect in the porous membrane tends to decrease, and among the fibrous suspended fine particles such as asbestos, There is a tendency for fibers with short fiber lengths to be difficult to collect through the hole, and the area of the through hole increases and the air flow rate increases, so a large capacity intake means is required and the device tends to be large Since both are seen, neither is preferable.

  The porous film can be disposed on one side of the holder so as to cover the through hole. Moreover, it can clamp between holders. Among these, those in which the porous film is disposed in the through hole by being sandwiched between the holders are preferably used. This is because the porous film can be held and protected in the holder.

  Here, the pressing means is biased by an elastic body such as a spring, or pressed by a screw, a clamp, or the like, so that the end face or cross section of the air path is pressed and brought into close contact with the filter holder. Is used. Note that if the holding means is formed to be extendable and movable in accordance with the number of filters attached to the filter attachment portion, a plurality of filters can be attached to the filter attachment portion in an overlapping manner. preferable.

As described above, according to the suspended particulate collection device of the present invention, the following advantageous effects can be obtained.
According to the invention of claim 1,
(1) Since a filter having a holder holding a porous film and a filter mounting part for detachably mounting the filter in the air passage and disposing the porous film in the air passage are collected, suspended particulates are collected. By removing the filter from the filter mounting part and mounting a new filter, it is possible to replace the filter without applying external force such as tensile force to the porous film of the filter. It is possible to provide a suspended particulate collection device that can accurately analyze the shape and particle size of the particulates and is excellent in the accuracy of the analysis.
(2) Since the filter in which the porous film is held by the holder is used, the structure and manufacturing process of the filter can be simplified, and a suspended particulate collection device having excellent filter productivity can be provided.
(3) Reduce the inner diameter of the air passage by reducing the pressure loss of the filter and the high collection efficiency of suspended particulates, and in addition, since most of the particles below the pore size of the porous membrane permeate, it is difficult to clog. This makes it possible to reduce the size of the suction means, simplifying the device configuration, reducing the size and weight of the device, and allowing it to be carried indoors and outdoors. Equipment can be provided.
(4) Since the filter can be made small and can be easily desorbed even if the filters are stacked in multiple stages, suspended particulates can be taken out immediately after collection and used as it is as a sample in an analytical instrument, allowing rapid analysis at the collection site. It is possible to provide a suspended particulate collection device that makes it possible.
(5) A plurality of filters having different hole diameters are overlapped, and the pore diameter of the porous membrane of the filter mounted on the downstream side of the air passage is set to be larger than the pore diameter of the porous membrane of the filter attached on the upstream side of the air passage. By reducing the size, suspended microparticles with different particle sizes can be collected in each porous membrane, so that multi-stage classification can be performed, particle size distribution can be measured, and suspended particles of a specific size can be measured. It is possible to provide a suspended particulate collection device that can be selectively collected.
(6) Since the filter mounting part is provided with a holding means for bringing the filter holder into close contact with the upstream air passage and the end face of the downstream air passage, the sucked gas leaks from between the holder and the air passage. Therefore, it is possible to provide a floating particulate collection device having a high quantitative property between the gas flow rate and the amount of suspended particulate collection. For this reason, the amount of gas that has passed through the porous membrane can be calculated based on the suction flow rate and suction time of the gas per unit time, and it depends on the suspended particulates at the collection site from this amount of gas and the number and type of collected suspended particulates. The degree of contamination can be measured.
(7) Since the holding means is formed to be movable according to the number of filters attached to the filter attachment portion, a plurality of filters can be attached to the filter attachment portion in an overlapping manner.
(8) Since the upstream side air passage can be moved forward or backward by the male screw portion as the holding means, a desired number of filters can be mounted on the filter mounting portion, and the flexibility is excellent.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional view of the main part in the vertical direction of the suspended particulate collection device according to Embodiment 1 of the present invention, FIG. 2 is an exploded perspective view of the filter, and FIG. 3 (a) is a plan view of the porous membrane of the filter. FIG. 4B is a perspective view of the porous film of the filter, and FIG. 4 is a cross-sectional view of the main part of the filter mounting portion in the horizontal direction.
In FIG. 1, reference numeral 1 denotes a suspended particulate collection device according to Embodiment 1 of the present invention, 2 denotes a casing of the suspended particulate collection device 1 formed in a box shape such as a rectangular parallelepiped, and 2 a is formed on the upper surface of the casing 2. The upper surface opening in which a filter 8 to be described later is inserted, 3 is an air passage penetrating the housing 2, 4 is an upstream air passage as the upstream air passage 3, and 4 a is a side surface of the housing 2. Are formed in the side opening portion 5 through which the upstream air passage 4 passes, 5 is an intake port formed at one end of the upstream air passage 4, 6 is a downstream air passage as the downstream air passage 3, and 7 is upstream. A filter mounting portion that is formed between the side air passage 4 and the downstream air passage 6 and detachably attaches a filter 8 to be described later to the air passage 3, and 8 is inserted into the housing 2 from the upper surface opening 2a. A filter 9 attached to the attachment portion 7 is a holder for the filter 8 formed in a plate shape made of synthetic resin such as polyolefin, etc. Is a substantially circular through-hole having an inner diameter of 5 to 10 mm that penetrates the holder 9 in the thickness direction, and 11 is disposed inside the through-hole 10 and is formed with a polymer compound or the like to a thickness of 0.1 to 20 μm. The porous membrane 12 is a suction means such as a suction pump disposed in the downstream flow path 6, and 13 is an exhaust port formed at the end of the downstream air path 6. In the present embodiment, a case where two filters 8 are stacked and mounted on the filter mounting portion 7 is shown.
In FIG. 2, 9 a and 9 b are divided holders having a rectangular outer shape and divided into two, and the holder 9 of the filter 8 is formed by sandwiching the porous film 11. 10a and 10b are through-holes penetrating each of the divided holders 9a and 9b, and 11a is a hole formed in the porous film 11 with the same shape and the same hole diameter of 0.1 to 20 μm.
In FIG. 3, X is solid or fibrous suspended particulates such as sea salt particles, yellow sand, metal oxides, pollen, dust, diesel exhaust particulates, asbestos and the like.
In FIG. 4, reference numeral 7 denotes a filter mounting portion disposed in the housing 2 below the upper surface opening 2 a, and 20 denotes a first filter mounting portion 7 formed in a plate shape or the like and having a predetermined portion fixed to the housing 2. Reference numerals 1 and 21 are side plates disposed on both sides of the first support portion 20 so as to face each other with a space slightly wider than the width of the filter 8, and 22 is formed in a plate shape or the like, and the first support portion 20 and the side plates 21. , 21, the second support portion 23 of the filter mounting portion 7 disposed at an appropriate interval, with the female support portion 20 penetrating into the first support portion 20, and a female screw portion being threaded on the inner peripheral surface. 1st support part through-hole communicated with 4a, 24 is a male screw as a pressing means formed on the outer peripheral surface of the upstream air passage 4 and screwed with a female screw part on the inner peripheral surface of the first support part through-hole 23 parts, 25 recess formed in an annular shape on the end surface of the upstream side air passages 4, 26 such as an O-ring mounted in the recess portion 25 of the Sea , 27 is a second support portion through hole that is provided in the second support portion 22 and is connected to the downstream air passage 6 and communicates with the first support portion through hole 23, and 28 is a second support portion that is connected to the downstream air passage 6. 2 A recess portion 29 formed in an annular shape in the second support portion 22 around the support portion through-hole 27, and 29 is a seal portion such as an O-ring attached to the recess portion 28.

An example of a method for producing the filter of the suspended particulate collection device according to Embodiment 1 of the present invention configured as described above will be described below.
Hydrophobic organic solvent solution (polymer concentration) in which a polymer compound such as polystyrene soluble in a hydrophobic organic solvent such as benzene and toluene and an amphiphilic polymer compound such as amphiphilic polyacrylamide are mixed at a predetermined ratio Is cast on a substrate such as a glass substrate or a ceramic substrate, and then a high-humidity gas (relative humidity 30 to 80%) such as air or inert gas is blown onto the substrate to make it hydrophobic. The organic solvent is evaporated. Since the hydrophobic organic solvent takes away the latent heat of the cast solution when it evaporates, the temperature of the solution surface decreases, water vapor condenses, and a small amount of water droplets adhere to the solution surface. The water droplets adhere to the solution surface in a finely aligned state, and form a hollow portion penetrating vertically in the cast solution. After all the hydrophobic organic solvent is evaporated and the polymer compound is solidified, the water droplets are evaporated to form the porous film 11 in which the holes 11a are formed in the portion where the droplets are attached. By adjusting the concentration of the solution to be cast, the amount of the solution to be cast, the type of the hydrophobic organic solvent, the relative humidity, temperature and flow rate of the high-humidity gas, the same shape and the same 0.1 to 20 μm A porous film 11 having a hole portion 11a formed with a hole diameter and having a thickness of 0.1 to 20 μm and an open area ratio of 45 to 75% is obtained.
The filter 8 is obtained by inserting and sandwiching the porous film 11 between the divided holders 9a and 9b.

Next, a method for using the suspended particulate collection device according to Embodiment 1 of the present invention configured as described above will be described below.
First, the upstream side air passage 4 is rotated to retreat the upstream side air passage 4 from the first support portion through hole 23. Next, one or a plurality of filters 8 are inserted between the side plates 21 and 21 of the filter mounting portion 7 from the upper surface opening 2a, and then the upstream air passage 4 is rotated to rotate the upstream air passage by the male screw portion 24. 4 is advanced, the seal portion 26 is pressed against the holder 9 of the filter 8 by the action of the male screw portion 24, the holder 9 of the filter 8 is brought into close contact with the seal portions 26, 29, and the holders 9, The porous films 11 and 11 of the filters 8 and 8 are disposed in the air passage 3 with the 9 close to each other.
Next, the suction means 12 is operated to suck in air or the like from the intake port 5, pass through the porous film 11, and exhaust from the exhaust port 13. As a result, the suspended fine particles X contained in the atmosphere or the like are collected in the porous film 11 larger than the pore diameter of the hole portion 11a, and the suspended fine particles X smaller than the pore diameter are used as a currency for the pore portion 11a of the porous film 11. The air is exhausted from the exhaust port 13.

As described above, since the suspended particulate collection device according to Embodiment 1 of the present invention is configured, the following operation is obtained.
(1) A porous membrane 11 having a hole 11a formed with the same shape and the same pore diameter of 0.1 to 20 μm and a thickness of 0.1 to 20 μm, and a holder 9 holding the porous membrane 11; The filter 8 having the filter 8 is detachably mounted on the air passage 3 and the filter mounting portion 7 for disposing the porous film 11 in the air passage 3 is provided. The filter 8 can be exchanged without applying an external force such as a tensile force to the porous film 11 of the filter 8 by removing it from the mounting part 7 and mounting a new filter 8. It is difficult to deform and can accurately analyze the shape and particle size of suspended particles.
(2) Since the porous film 11 is held by the holder 9 in the filter 8, the strength of the porous film 11 can be secured, and the porous film 11 having a smaller area can be used. The manufacturing process of 11 can be simplified and the productivity of the filter 8 is excellent.
(3) Since the porous membrane 11 has the pores 11a formed with the same shape and the same pore diameter of 0.1 to 20 μm, most of the particles smaller than the pore diameter of the porous membrane 11 permeate through the pore diameter. Since only large particles are collected in the porous film 11 and are not easily clogged, the suction means 12 can be reduced in size by reducing the inner diameter of the air passage 3, so that the apparatus configuration can be simplified. The device can be reduced in size and weight, and can be carried indoors and outdoors and is excellent in portability.
(4) Since the filter 8 includes the through hole 10 penetrating in the thickness direction of the holder 9 and the porous film 11 is disposed in the through hole 10, the inner diameter of the through hole 10 is reduced, so The deformation of the porous film 11 when the gas passes through the film 11 can be reduced, and the hole 11a is prevented from being deformed or widened, thereby enhancing the classification effect of the floating fine particles in the porous film 11. In addition, it is possible to increase the collection efficiency when collecting fibrous suspended fine particles such as asbestos.
(5) Since the filter mounting portion 7 includes the screw portion 24 as a holding means for bringing the holder 9 of the filter 8 and the end surfaces of the upstream air passage 4 and the downstream air passage 6 into close contact with each other, the holder 9 and the upstream The gas sucked from between the side air passage 4 and the downstream air passage 6 can be prevented from leaking, and the quantification of the gas flow rate and the amount of trapped particulate matter is enhanced, and the suction means 12 Gas can be passed through the porous membrane 11 without leakage, and the amount of gas passing through the porous membrane 11 can be calculated based on the suction flow rate and suction time of the gas per unit time. The degree of contamination by suspended fine particles at the collection site can be measured from the number and type of suspended suspended particulates.
(6) Since the upstream side air passage 4 can be moved forward or backward by the male screw portion 24 as a holding means, a desired number of filters 8 can be mounted on the filter mounting portion 7 and the flexibility is excellent.
(7) A plurality of filters 8 having different hole diameters in the hole portion 11 a are overlapped, and the hole diameter of the porous film 11 of the filter 8 attached on the downstream side of the air passage 3 is set to the filter 8 attached on the upstream side of the air passage 3. By making it smaller than the pore diameter of each porous film 11, it is possible to collect suspended fine particles having different particle diameters in each porous film 11, so that multistage classification is possible, and particle size distribution is obtained by counting and analyzing each. Can be measured.
(8) Since the filter 8 in which the porous film 11 is sandwiched between the divided holders 9a and 9b and the porous film 11 is disposed in the through hole 10 is used, a plurality of filters 8 are overlapped to form the filter mounting portion 7 Since the porous membranes 11 do not come into contact with each other even when mounted, the suspended fine particles collected in the porous membrane 11 can be prevented from rubbing against another porous membrane, and the shape can be prevented from collapsing. Shape analysis can be performed accurately. Further, since the stacked porous films 11 and 11 are separated by the thickness of the holder 9, the airflow that has passed through the upstream porous film 11 is disturbed before passing through the downstream porous film 11. Since the suspended fine particles therein are dispersed, the suspended fine particles 11 can also be collected in the downstream porous membrane 11 similarly to the upstream porous membrane 11, and the influence of a plurality of the filters 8 being stacked. The suspended fine particles can be collected in each filter 8 (particularly, the downstream filter 8) without being subjected to the above.

Here, in the present embodiment, the pressing means is described as being pressed by the male screw portion 24, but is not limited to this, and is biased by an elastic body such as a spring, or a clamp or the like. Thus, any material can be used as long as it can be brought into pressure contact with the holder 9 of the filter 8 so that the through hole 10, the upstream air passage 4, and the downstream air passage 6 can communicate with each other. In this case, the same action as described above can be obtained.
Moreover, although the case where the filter 8 is mounted between the upstream side air path 4 and the downstream side air path 6 has been described, the filter 8 may be mounted on the intake port 5 or the exhaust port 13. In this case, the same action as described above can be obtained.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
Example 1
Optimum temperature of 8 mL of chloroform solution (0.1 to 2 wt% polymer concentration) in which poly-ε-caprolactone with an average molecular weight of 70,000 to 100,000 and amphiphilic polyacrylamide are mixed at a weight ratio of 10: 1 The film is cast on a glass substrate in a formed film forming chamber, high humidity air having a relative humidity of 30 to 80% is blown at a flow rate of 1 to 20 L / min, and chloroform is evaporated to obtain a thickness of 1.5 to A porous film having 2.0 μm, an average pore size of 2.63 μm, a standard deviation of 0.331 μm, a coefficient of variation of 0.12, a maximum of 3.23 μm, and a minimum of 2.12 μm was obtained.
The porous film was sandwiched between the divided holders to obtain the filter of Example 1.
After mounting a filter with a membrane filter (Mixed Cellulose Ester, Pore size 0.8 μm, manufactured by ADVANTEC) on the downstream side of the filter of Example 1 and mounting it on the filter mounting part, this suspended particulate collection device Was brought into a room in which glass fiber particles mixed with asbestos were sprayed onto the wall, and the air in the room was sucked at a suction speed of 3.5 L / min for 1 hour by operating a suction pump as a suction means.
After removing the filter from the suspended particulate collection device, the suspended particulate collected on the filter and membrane filter of Example 1 is shaped using a wet scanning electron microscope (Hitachi) and a digital microscope (made by Keyence). Observed. In addition, when observing the suspended fine particles collected by the membrane filter, the membrane filter was subjected to a transparent treatment using acetone or the like as a pretreatment.
Of the observed suspended fine particles, those having an aspect ratio of 3 or more were regarded as fibrous particles, and the number and length were measured.

(Comparative Example 1)
On a glass substrate, 8 mL of a chloroform solution (0.1 to 2 wt% as a polymer concentration) in which poly-ε-caprolactone having an average molecular weight of 70,000 to 100,000 and amphiphilic polyacrylamide were mixed at a weight ratio of 10: 1 By blowing high-humidity air with a relative humidity of 30 to 80% at a flow rate of 1 to 20 L / min and evaporating chloroform to obtain a thickness of 1.3 to 2.3 μm and an average pore size of 3.07 μm. A porous membrane having pores with a standard deviation of 0.837 μm, a coefficient of variation of 0.27, a maximum of 4.73 μm, and a minimum of 1.99 μm was obtained.
The porous film was sandwiched between the divided holders to obtain a filter of Comparative Example 1.
The number, length, and thickness of the fibrous particles were measured in the same manner as in Example 1, except that the filter of Comparative Example 1 was mounted on the upstream side of the membrane filter instead of the filter of Example 1.

The results of measuring the number and length of the fibrous particles are shown in FIGS.
FIG. 5 is a diagram showing the length and frequency of the fibrous particles collected on the filter and membrane filter of Example 1, and FIG. 6 is the length of the fibrous particles collected on the filter and membrane filter of Comparative Example 1. It is a figure which shows the frequency. In the figure, the black dots are the measured values of the fibrous particles collected in the filter of Example 1 or Comparative Example 1, and the white dots are the measurements of the fibrous particles collected in the membrane filter. Value.
As apparent from FIGS. 5 and 6, in the filter of Comparative Example 1, fibrous particles having a length of 5 μm or less pass through many pores and are collected by the membrane filter, whereas the filter of Example 1 Then, it was confirmed that the filter can be collected at a high collection rate of 90% or more. In addition, 80% of the fibrous particles that passed through the filter of Comparative Example 1 had a thickness of 2 μm or less (maximum 4 μm, average 1.71 μm), and the average length was 8.41 μm.
As described above, according to this example, the porous membrane has a standard deviation of the pores of 0.5 μm or less, or the variation coefficient of the pores is 0.2 or less and the pore diameter distribution is extremely narrow. It has been clarified that the collection efficiency in collecting the fibrous suspended particulates can be increased.

  The present invention relates to a suspended particulate collection device that collects suspended particulates such as pollen, yellow sand, and asbestos that are suspended in the atmosphere, etc., and the shape of the collected suspended particulates because the pores of the porous film of the filter are difficult to deform. The particle size can be accurately analyzed, the accuracy of the analysis is excellent, the filter construction and the manufacturing process can be simplified, the filter productivity is excellent, and the filter pressure loss is small. Since it is difficult to clog, the suction means can be reduced in size by reducing the inner diameter of the air passage. Therefore, the device configuration can be simplified, the device can be reduced in size and weight, and can be carried indoors and outdoors. In addition, it is possible to provide a floating particle collecting apparatus capable of quickly taking out a filter after collecting floating particles and performing rapid instrumental analysis.

Sectional drawing of the principal part of the perpendicular direction of the suspended particulate collection apparatus in Embodiment 1. Exploded perspective view of filter (A) Plan view of porous membrane of filter (b) Perspective view of porous membrane of filter Cross-sectional view of the main part of the filter mounting part in the horizontal direction Length and frequency of fibrous particles collected in the filter and membrane filter of Example 1 Length and frequency of fibrous particles collected in the filter and membrane filter of Comparative Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airborne particle collection apparatus 2 Housing | casing 2a Upper surface opening part 3 Air path 4 Upstream air path 4a Side surface opening part 5 Inlet 6 Downstream side air path 7 Filter mounting part 8 Filter 9 Holder 9a, 9b Split holder 10, 10a, 10b Through-hole 11 Porous membrane 11a Hole 12 Suction means 13 Exhaust port 20 First support part 21 Side plate 22 Second support part 23 First support part through-hole 24 Male screw part (holding means)
25, 28 Recessed part 26, 29 Seal part 27 Second support part through hole

Claims (1)

A suspended particulate collection device that captures suspended particulates using a filter in which a porous film is held by a holder,
A housing having an opening for inserting the filter, an air passage penetrating into the housing, having an air inlet at one end and an air outlet at the other, and disposed in the housing. A filter mounting portion in which one or a plurality of the filters inserted from the opening portion are detachably mounted and the porous membrane is disposed in the air passage; and suction means disposed in the air passage; Prepared ,
The air path includes an upstream air path in which the intake port is formed at one end, and a downstream air path in which the exhaust port is formed at an end,
The filter mounting portion is formed between the upstream air passage and the downstream air passage, and is fixed to the housing. The first support portion penetrates the first support portion and is formed on the inner peripheral surface. A first support part through-hole into which a female screw part is engraved; a second support part disposed at a distance from the first support part; and the first support part penetrating through the second support part. A second support part through hole communicating with the through hole,
The outer circumferential surface of the upstream air passage is screwed with the screw portion of the inner circumferential surface of the first support portion through hole, and the holder of the filter and the end surfaces of the upstream air passage and the downstream air passage are connected. An apparatus for collecting suspended particulates , wherein a male screw portion is formed as a pressing means for close contact, and the downstream air passage is connected to the second support portion through hole .

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