TW201932182A - Filter material-use nonwoven fabric and method for manufacturing same - Google Patents

Abstract

To provide a filter material-use nonwoven fabric which exhibits excellent durability and good dust shake-off performance, which is stable over long periods and is capable of filtering dust in exhaust gas, and with which dust clogs according to the filter conditions desired for filter material-use nonwoven fabrics, particularly nonwoven fabrics used in bag filters, can be prevented. A filter material-use nonwoven fabric comprises 20 to 100% by mass of amorphous polyphenylene sulfide fibers and 0 to 80% by mass of heat-resistant fibers, the fabric having the basis weight of 80 to 400 g/m2, wherein: the initial outlet dust concentration obtained in a VDI test is 1.5 mg/m3 or less; and the value of (post-load residual pressure loss/initial residual pressure loss) as obtained in a VDI test is 2.5 or less.

Description

Non-woven fabric for filter material, manufacturing method thereof, felt, filter

The present invention relates to a nonwoven fabric for use in a filter material which can be preferably used for a filter bag including amorphous polyphenylene sulfide fibers and heat-resistant fibers, and is excellent in durability and good in dust fallability, and A non-woven fabric for a filter material which can stably perform dust filtration in exhaust gas for a long period of time and a method for producing the same.

Among the filter materials for cleaning the air, there are a filter material for internal filtration and a filter material for surface filtration. For the filter bag used as the dust collector filter, a filter material for surface filtration is used. The so-called surface filtration uses the surface of the filter material to collect dust, so that the dust cake (the layer of dust) is formed on the surface of the filter material, and the dust is gradually collected by the dust cake, and if the dust cake reaches a certain thickness, it is empty. The air pressure removes the dust cake from the surface of the filter material, and again forms a dust cake on the surface of the filter material, and the above operation is repeated to perform filtration.

Exhaust gas discharged from coal-fired boilers, municipal waste incinerators, industrial waste incinerators, etc., in addition to coal dust, also contains harmful substances such as dioxin, which is very important for air pollution prevention. Nowadays, due to the global population growth and the high power demand due to industrial development, it is also reported that there are problems such as PM (Particulate Matter) 2.5 caused by the operation of coal-fired boilers in thermal power stations. The high performance of the filter bag is used to respond to environmental measures.

Further, the contents of the environmental specifications vary depending on the country and the region, and the gas conditions in the dust collector are also different. Therefore, it is expected that a filter bag for a wider range will be increasingly required in the future.

In order to make the dust releasability good to reduce clogging due to dust, and to perform exhaust gas treatment stably for a long period of time, various filter bags for filter bags are being studied. Polytetrafluoroethylene A filter material in which a film having a pore diameter of about 2 μm composed of ethylene (hereinafter referred to as PTFE) is adhered to a filter surface of a nonwoven fabric or a woven fabric to improve dust plucking property.

Further, a filter material having a film in which a slit is formed in the thickness direction of the layer to prevent dust from leaking is proposed (for example, Patent Document 1); and the density of the needle obtained by needle rolling is increased to be densified. A filter material (for example, Patent Document 2); a filter material having a dust-repellent property and a dust-collecting property which is excellent in a polyphenylene sulfide (hereinafter referred to as PPS) fiber having a single fiber fineness of 2.0 dtex or less.

In the case of the above-described various methods, the high-collection efficiency and the long-term stable exhaust gas treatment are required. However, when the filter material of the dust to be passed is captured by the film inside the filter layer described in Patent Document 1, the following problems occur. The filter layer itself composed of fibers has a large void ratio, so that clogging is caused, and exhaust gas filtration cannot be performed stably for a long period of time.

In the case where the filter material is densified by needle rolling and the void ratio is reduced as described in Patent Document 2, the support layer inside the filter material is damaged by the needle to cause a strong decrease, or the fiber itself of the filter layer is damaged. problem.

When the single fiber fineness of the fiber disposed on the filter surface is 2.0 dtex or less and the filter surface is densified, the collection efficiency is excellent, but the rigidity and the abrasion resistance at high temperatures are high. If it is insufficient, the physical property of the filter material deteriorates and the damage occurs at the time of use.

Thus, the previously known filter material for the filter bag is a fiber, and is a three-dimensional structure such as a non-woven fabric or a fabric. Therefore, under the filter bag filtration mechanism mainly based on surface filtration, the long-term stability of the film laminate is not achieved. Sex, filtering accuracy. However, when the filter material obtained by the method of film lamination is used for the filter bag for a dust collector, as shown in Patent Document 4, although the dust jet property is excellent by the pulse jet method, it is excellent The material has poor adhesion (this is the characteristic of PTFE), and there is a long-term pulse jetting operation that causes the film itself to pass. The problem of peeling off the filter surface. In addition, it is pointed out that the cost of processing is very high.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 1-715169.

Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 9-57026.

Patent Document 3: Japanese Laid-Open Patent Publication No. Hei 10-165729.

Patent Document 4: Japanese Laid-Open Patent Publication No. 2000-140530.

An object of the present invention is to provide a non-woven fabric for a filter material, in particular, a dust-free clogging corresponding to a filter condition required for a non-woven fabric for a filter bag, excellent durability, good dust fall property, and long-term stable operation. Non-woven fabric used for the filter material filtered by dust in the exhaust gas.

As described above, the filtration mechanism of the filter bag utilizes the dust cake formed on the filter surface for dust collection. The inventors have found that the particulate matter penetrating the filter material is mostly disposed before the surface layer of the filter surface is sufficiently thick. Invade into the filter material.

Since the membrane-laminated filter material has a uniform diameter in the through-holes of the film, it has a characteristic that a certain residual pressure loss can be obtained even if the initial residual pressure loss is high, and it is stable without being affected by the formation of the dust cake. Dust collection performance.

Therefore, in order to reduce the exhaust gas concentration using only the nonwoven fabric, the inventors focused on the fact that the particulate matter stays on the surface of the filter material until the surface of the filter material sufficiently forms the dust cake, and it is necessary to achieve the situation. The material of the filter material and the processing thereof are appropriately formulated to achieve the present invention.

That is, the present invention is as follows.

A non-woven fabric for a filter material comprising 20% by mass to 100% by mass of amorphous polyphenylene sulfide fibers and 0% by mass to 80% by mass of heat resistant fibers, and having a basis weight of 80 g/m ² to 400 g /m ² is not woven, and the initial outlet dust concentration obtained by VDI (Verein Deutscher Ingenieure; German Institute of Engineers) is 1.5 mg/m ³ or less, residual pressure loss after load obtained by VDI test / initial residual pressure The value of the loss is less than 2.5.

2. The nonwoven fabric used for the filter material according to the above 1, wherein the amorphous polyphenylene sulfide fiber has a fineness of from 1 dtex to 25 dtex and a fiber length of from 30 mm to 90 mm.

3. The nonwoven fabric for a filter material according to the above 1 or 2, wherein the heat resistant fiber comprises a material selected from the group consisting of crystalline polyphenylene sulfide fibers, aromatic polyamide fibers, fluorine fibers, polyimine fibers, carbon fibers, and glass fibers. More than one of the fibers.

A felt comprising the non-woven fabric used for the filter material according to any one of the above 1 to 3 as a filter layer, and integrated with the support layer and the reinforcing layer.

A filter comprising the felt according to 4 above.

A method for producing a nonwoven fabric for use in a filter material, which is directed to a short fiber nonwoven fabric comprising 20% by mass to 100% by mass of amorphous polyphenylene sulfide fibers and 0% by mass to 80% by mass of heat resistant fibers by heating The cross-sectional shape of one portion of the amorphous polyphenylene sulfide fiber is deformed into a flat cross section by pressure treatment, and/or film formation by melting.

7. The method for producing a nonwoven fabric for use in a filter material according to the above 6, wherein the heating and pressurizing treatment are carried out at a temperature of from 110 ° C to 190 ° C and a pressure of from 20 kg/m ² to 50 kg/m ² .

The non-woven fabric used for the filter material of the present invention can provide, in particular, a dust-free clogging corresponding to the filtration conditions required for the non-woven fabric of the filter bag, good dust sag, and long-term stable durability of dust filtration in the exhaust gas. Non-woven fabric for excellent filter materials.

Hereinafter, the present invention will be described in detail.

The resin used for the amorphous PPS fiber of the present invention is preferably a linear PPS resin, preferably having a load of 49 N by ASTM (American Society for Testing Materials) D-1238-82 method. The melt flow rate of the PPS measured under the conditions of 315.6 ° C was 50 g/10 min to 160 g/10 min. In various applications such as filter media for filter bags, it is not only required to have simple heat resistance or chemical resistance, but also, for example, the strength required for the filter body. Therefore, for example, in order to obtain high strength as a fiber, there is a method in which an unreacted chlorine group is previously left by using trichlorobenzene or the like in a polymerization stage, and an oxygen atmosphere or a nitrogen atmosphere is used in a polymer stage before spinning. In the high-temperature treatment, the crosslinking reaction is caused by the unreacted chlorine group to increase the degree of polymerization, and the initial strength required as a fiber is obtained. Further, even in the case of a polymer having a relatively low melt flow rate (low molecular weight), the molecular weight can be increased by temporarily crosslinking in an oxygen atmosphere before spinning, and the fiber itself can satisfy the necessary physical properties such as strength. However, in this method, a fiber composed of a polymer obtained by a one-time crosslinking reaction of a polymer having a relatively low molecular weight is determined by ESCA (Electron Spectroscopy for Chemical Analysis). Since the bond centered on the sulfur atom already contains a bond of -SO- or -SO ₂ -, such a method of increasing the degree of polymerization by crosslinking or oxidizing at one time cannot obtain long-term heat resistance. The PPS of the present invention is obtained by spinning a linear polymer composed of a melt flow rate of PPS of 50 g/10 min to 160 g/10 min measured by the ASTM D-1238-82 method under the conditions of a load of 49 N and a temperature of 315.6 ° C. For example, when ESCA is used to measure a bond state centered on a sulfur atom, it is preferable that 95 atom% or more of the bond is a thioether bond, more preferably 98 atom% or more is a thioether bond, and further preferably 100 atom%. It is a thioether bond.

The amorphous PPS fiber of the present invention is a fiber composed of a polymer having a P-phenyl sulfide (-C ₆ H ₄ -S-) unit, and is preferably contained in an amount of 70% by mass or more, more preferably A fiber composed of a linear polymer of 90% by mass or more of a P-phenylene sulfide repeating unit. Since the PPS fiber is excellent in heat resistance, chemical resistance to various chemicals, and flame retardancy, it has a very high performance as a filter material for a filter bag in a use range of 190 ° C or lower.

The PPS resin used for the amorphous PPS fiber of the present invention preferably has a melt flow rate of from 50 g/10 min to 160 g/10 min measured by the ASTM D-1238-82 method under the conditions of a load of 49 N and a temperature of 315.6 °C. In order to obtain sufficient long-term heat resistance or strength, a linear polymer is preferred and the degree of polymerization is higher. However, if the melt flow rate is less than 50 g/10 min, the viscosity is not so high at a high temperature, and the productivity is poor due to an increase in pressure loss at the time of spinning. In addition, when the melt flow rate is more than 160 g/10 min, that is, the molecular weight is reduced, the pressure loss at the time of spinning can be suppressed, but the molecular weight distribution becomes large, and if a higher molecular weight resin is contained in a low pressure loss state, there is The possibility that the high molecular weight resin has a poor molten state and affects the breakage at the time of spinning or the like. Further, the low molecular weight is also poor from the viewpoint of long-term heat resistance. From this point of view, the melt flow rate of the PPS resin for the amorphous PPS fiber is preferably from 50 g/10 min to 160 g/10 min, more preferably from 80 g/10 min to 140 g/10 min. Further, the linear PPS resin is excellent in processability as compared with the crosslinked or semi-crosslinked PPS resin, because it is excellent in long-term heat resistance and excellent in thermal stability during melting.

The PPS resin used in the amorphous PPS fiber of the present invention can be obtained by a method in which an alkali metal sulfide and a dihalogenated aromatic compound are polymerized in a polar organic solvent. As the alkali metal sulfide, for example, sodium sulfide, lithium sulfide, potassium sulfide or the like or a mixture of these or the like can be used. Among these, sodium sulfide is the most economically superior and is therefore commonly used.

Further, examples of the dihalogenated compound include dihalogenated benzene such as p-dichlorobenzene, o-dichlorobenzene or m-dichlorobenzene, dihalogenated naphthalene such as 1,4-dichloronaphthalene, and dihalogenated benzene. Formic acid, two Halogenated benzophenone, dihalogenated phenyl ether, etc., p-dichlorobenzene is optimally used from the viewpoint of physical properties and economy. Further, in general, a polyhalogenated aromatic compound having three or more halogen substituents per molecule in combination with a small amount of branched structure is known, and trichlorobenzene or the like is exemplified, but the present invention is a line. The resin means that it does not substantially have such a semi-crosslinked structure.

The amorphous PPS fiber of the present invention preferably has a circular cross section, and has a fineness of preferably 1 dtex to 25 dtex, more preferably 2 dtex to 15 dtex, further preferably 3 dtex to 10 dtex, and a fiber length of preferably 30 mm to 90 mm. The number is preferably from 3/25 mm to 20/25 mm.

The amorphous PPS fiber of the present invention can be obtained by a melt spinning method using the aforementioned PPS resin. The molten PPS resin was extruded from a nozzle, and spun at a spinning speed of 500 m/min to 2000 m/min to obtain an amorphous PPS fiber. The crimping of the amorphous PPS fiber can be imparted by using a press-in crimping machine or the like which is usually used. At this time, the crimped shape can be stabilized by removing moisture at a drying temperature of 50 ° C to 80 ° C and a drying time of 20 minutes to 1 hour after crimping.

The heat resistant fiber of the present invention is preferably a fiber selected from the group consisting of crystalline PPS fibers, aromatic polyamide fibers, fluorine fibers, polyimine fibers, carbon fibers, and glass fibers, and more preferably selected from crystalline PPS fibers. , aramid fiber, PTFE fiber as fluorofiber and fiber in polyimine fiber.

The heat resistant fiber of the present invention preferably has a fineness of 0.5 dtex to 15 dtex, a fiber length of 30 mm to 90 mm, and a crimping number of 3 / 25 mm to 20 / 25 mm.

The nonwoven fabric of the present invention contains 20% by mass to 100% by mass of the amorphous PPS fiber and 0% by mass to 80% by mass of the heat resistant fiber. When the content ratio of the amorphous PPS fiber of the non-woven fabric of the present invention is less than 20% by mass, the surface of the obtained non-woven fabric is insufficient in smoothing and low voiding, and the residual pressure loss after the load obtained by the VDI test/initial residual pressure The value of the loss becomes larger. The content of the amorphous PPS fiber is preferably from 25% by mass to 95% by mass, more preferably from 30% by mass to 90% by mass, even more preferably from 35% by mass to 85% by mass. The content of the heat resistant fiber is preferably 5 The mass% to 75% by mass, more preferably 10% by mass to 70% by mass, and still more preferably 15% by mass to 65% by mass.

The nonwoven fabric of the present invention has a basis weight of from 80 g/m ² to 400 g/m ² , preferably from 90 g/m ² to 350 g/m ² , more preferably from 100 g/m ² to 250 g/m ² . When the basis weight is less than 80 g/m ² , the particulate matter cannot stay on the surface of the filter material until the dust cake is sufficiently formed on the surface of the filter material, and the initial outlet dust concentration obtained by the VDI test becomes high. Preferably, if it exceeds 400 g/m ² , the residual pressure loss at the initial stage of the filter material becomes high and is not preferable.

The thickness of the nonwoven fabric of the present invention is preferably from 0.6 mm to 4.5 mm, more preferably from 0.7 mm to 4.0 mm, and still more preferably from 0.8 mm to 3.0 mm. When the thickness is less than 0.6 mm, it is impossible to allow the particulate matter to stay on the surface of the filter material until the surface of the filter material is sufficiently formed on the surface of the filter material, and the initial outlet dust concentration obtained by the VDI test becomes high and is unsatisfactory. At 4.5 mm, the residual pressure loss at the initial stage of the filter material becomes high and is not good.

The nonwoven fabric of the present invention is preferably a concentration of the outlet dust after the load obtained by the VDI test of 0.5 mg/m ³ or less, more preferably 0.45 mg/m ³ or less, still more preferably 0 mg/m ³ to 0.35 mg/m ³ . If the outlet dust concentration after the load exceeds 0.5 mg/m ³ , it is considered that the dust is directly transmitted through the filter material and is not preferable.

The initial nonwoven dust concentration obtained by the VDI test of the nonwoven fabric of the present invention is 1.5 mg/m ³ or less, more preferably 1.3 mg/m ³ , and still more preferably 0 to 1.2 mg/m ³ . If the initial outlet dust concentration exceeds 1.5 mg/m ³ , it can be said that the dust is not directly transmitted through the filter material at the initial stage of use.

The non-woven fabric of the present invention has a residual pressure loss after the load obtained by the VDI test and an initial residual pressure loss of 2.5 or less, preferably 2.3 or less, more preferably 2.0 or less. If the value of the residual pressure loss after the load/initial value exceeds 2.5, the filter material after the load is clogged by the dust, and even if the dust is dropped, the residual pressure loss does not recover and is not preferable.

The non-woven fabric of the present invention is a residual pressure loss after the load obtained by the VDI test. It is preferably 500 Pa or less, more preferably 400 Pa or less, and still more preferably 300 Pa or less.

The initial residual pressure loss obtained by the VDI test of the nonwoven fabric of the present invention is preferably 300 Pa or less, more preferably 250 Pa, and still more preferably 200 Pa or less.

The nonwoven fabric of the present invention can be obtained by the following method. First, the amorphous PPS fiber and the heat-resistant fiber are mixed at a predetermined ratio to form a card, or a card is formed by forming a card web from the amorphous PPS fiber and the heat-resistant fiber, respectively. Or spunlace and entangled to obtain short fiber non-woven fabric. As a method of obtaining a short fiber nonwoven fabric, a papermaking method, a thermal bonding method, or a chemical bonding method can also be used. Then, the obtained short fiber nonwoven fabric is subjected to heat and pressure treatment at a temperature of preferably 110 to 190 ° C, more preferably 120 ° C to 180 ° C, and a pressure of 20 kg / m ² to 50 kg / m ² , thereby obtaining the present The invention is not woven. In the nonwoven fabric of the present invention, the cross-sectional shape of a portion of the amorphous PPS fiber contained in the nonwoven fabric is changed from a circular cross-sectional shape to a flat cross-section, and/or by melting, in particular, by heating and pressurizing at the above-described heating temperature. When it is used as a filter material, the surface of the non-woven fabric is heated and the pressure-treated surface (hereinafter referred to as a non-woven filter surface) is smoothed and has a low void, and is perpendicular to the non-woven filter surface. The gap in the direction is flattened. Therefore, when a non-woven fabric is used as the filter material, the intrusion of the particulate matter in the target fluid flowing from the non-woven fabric filter surface side into the non-woven fabric can be suppressed, and the amount of the particulate matter on the non-woven fabric filter surface can be increased.

The felt of the three-layer structure in which the nonwoven fabric used for the filter material of the present invention is used as a surface layer and the support layer and the reinforcing layer are laminated in the above-described order is also preferably used. As the preferred basis weight of the felt, the installation of the filter bag as the main use and the mounting property when the felt of the dust collector is detached, the cracking and damage of the felt during the operation of the dust collector, and the production of the felt production The amount of the fluid, the fluid throughput, etc., is preferably from 300 g/m ² to 800 g/m ² , more preferably from 400 g/m ² to 700 g/m ² .

The non-woven fabric used for the filter material of the present invention is used for laminating with the support layer and the reinforcing layer In the case of a layered felt, the heating and pressing treatment for obtaining the non-woven fabric for the filter material may be performed by integrating the surface layer, the support layer and the reinforcing layer layer, and the temperature and pressure from the surface layer side. Heat and pressurize.

As the support layer, a mesh composed of a crystalline PPS fiber, an aromatic polyamide fiber, a fluorine fiber, a polyimide fiber, a carbon fiber or a glass fiber, a single filament or a textile yarn is preferred. The coarse fabric, as the woven density of the woven fabric, is preferably from 8 / 2.54 cm to 40 / 2.54 cm in both the warp direction and the weft direction. As the weave structure, there are plain weave, double weave, three-layer weave, twill weave, satin weave, etc., and it is preferably a low-cost and general-purpose plain weave.

The reinforcing layer is preferably a nonwoven fabric composed of any one of a crystalline PPS fiber, an aromatic polyamide fiber, a fluorine fiber, a polyimide fiber, a carbon fiber, or a glass fiber.

The felt obtained by using the nonwoven fabric of the filter material of the present invention as a surface layer and laminated with the support layer and the reinforcing layer in the above-described order is obtained, for example, by the following production method. First, the amorphous PPS fiber and the heat-resistant fiber are mixed at a predetermined ratio to form a card web, and the crystalline PPS fiber, the aromatic polyamide fiber, the fluorine fiber, and the polyimine as the support layer. A thick fabric layer composed of a plurality of filaments of fibers, carbon fibers or glass fibers is integrated by needle rolling to form a laminate of a filter layer and a support layer. On the side of the support layer of the laminate, a carding web composed of any one or more of short fibers of crystalline PPS fiber, aromatic polyamide fiber, fluorine fiber, polyimine fiber, carbon fiber or glass fiber is laminated. Furthermore, it is integrated by needle rolling from both sides. The laminated product of a three-layer structure resulting from the side of the filter layer by the temperature is 110 ℃ to 190 deg.] C and a pressure of 20kg / m ² was heated to 50kg / m ² of hot calender treatment under pressure to obtain felt.

(Example)

Hereinafter, the present invention will be more specifically described by way of examples. Furthermore, the present invention It is not limited to only these embodiments.

(1) Fineness

The measurement was carried out based on JIS (Japanese Industrial Standard) L1015 (2010) 8.5.

(2) Unit weight

The measurement was performed based on JIS L1913 (2010) 6.2.

(3) VDI test

The measurement was carried out in accordance with the VDI 3926 test, sample size, evaluation conditions, and the like as follows.

Sample size: Φ154mm

Test dust: 3.5μm, Pural NF, made in Germany

Dust concentration: 5g/m ³

Filtration speed: 2m/min

Temperature: 160 ° C

Dust fall: 1000Pa

Aging interval: 5sec

Pulse pressure: 0.5MPa

Pulse injection time: 50msec

testing method

(i) 30 dust collection and slumping under the control of 1000 Pa fall pressure loss.

The initial outlet dust concentration (mg/m ³ ) and residual pressure loss (Pa) were measured.

(ii) The aging treatment was repeated 10,000 times at intervals of 5 seconds. In order to stabilize the dust collecting performance of the filter cloth after aging, the stabilizing treatment was repeated 10 times under the control of the drop pressure loss of 1000 Pa. The outlet dust concentration (mg/m ³ ) and residual pressure loss (Pa) after the load were measured.

(Example 1)

Amorphous PPS fiber (denier: 5.5 dtex, fiber length: 60 mm, cross-sectional shape: circular cross section) manufactured by Toyobo Co., Ltd. 50% by mass and PPS fiber manufactured by Toyobo Co., Ltd. (denier 2.2 dtex, fiber length: 60 mm , cross-sectional shape: circular cross section) 50% by mass of mixed cotton, which was entangled by needle rolling, and then subjected to heating and pressure treatment using a hot calender roll having a temperature of 120 ° C and a pressure of 35 kg/m ² . Further, singeing treatment was performed on the surface of the non-woven fabric to be a filter surface, and a nonwoven fabric for a filter material having a basis weight of 100 g/m ² was obtained.

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Example 2)

A non-woven fabric for a filter material having a basis weight of 100 g/m ² was obtained in the same manner as in Example 1 except that the heat and pressure treatment were carried out by a hot calender roll having a temperature of 150 ° C and a pressure of 35 kg/m ² .

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Example 3)

A non-woven fabric for a filter material having a basis weight of 100 g/m ² was obtained in the same manner as in Example 1 except that the heat and pressure treatment were carried out by a hot calender roll having a temperature of 170 ° C and a pressure of 35 kg/m ² .

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Example 4)

Amorphous PPS fiber manufactured by Toyobo Co., Ltd. (fineness: 1.5 dtex, fiber length: 60 mm, cross-sectional shape: circular cross section) 50% by mass and PPS fiber manufactured by Toyobo Co., Ltd. (denier 2.2 dtex, fiber length: 60 mm , cross-sectional shape: circular cross section) 50% by mass of mixed cotton, which was interlaced by needle rolling, and then subjected to heating and pressure treatment using a hot calender roll having a temperature of 150 ° C and a pressure of 35 kg/m ² . Further, singeing treatment was performed on the surface of the non-woven fabric to be a filter surface, and a nonwoven fabric for a filter material having a basis weight of 100 g/m ² was obtained.

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Comparative Example 1)

A non-woven fabric for a filter material having a basis weight of 100 g/m ² was obtained in the same manner as in Example 1 except that the heating and pressurization treatments were not carried out.

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Comparative Example 2)

A non-woven fabric for a filter material having a basis weight of 100 g/m ² was obtained in the same manner as in Example 1 except that the heat and pressure treatment were carried out by a hot calender roll having a temperature of 100 ° C and a pressure of 35 kg/m ² .

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Comparative Example 3)

The PPS fiber (denier 2.2 dtex, fiber length: 60 mm, cross-sectional shape: circular cross section) manufactured by Toyobo Co., Ltd. was intertwined by needle rolling, and then heated by a hot calender roll having a temperature of 170 ° C and a pressure of 35 kg/m ² . , pressure treatment. Further, singeing treatment was performed on the surface of the non-woven fabric to be a filter surface, and a nonwoven fabric for a filter material having a basis weight of 100 g/m ² was obtained.

The physical property measurement results of the nonwoven fabric used for the obtained filter material are summarized in Table 1.

(Example 5)

A non-woven fabric for a filter layer having a basis weight of 100 g/m ^{2 was} produced in the same manner as in Example 2 except that the heating, the pressure treatment, and the singeing were not carried out.

As a support layer, a crystalline PPS multifilament fiber (denier: 250 dtex, 60 filament, tensile strength: 4.3 cN/dtex) of Toyobo Co., Ltd. was produced, and a basis weight of 85 g/m ² was produced. Fabric.

As a reinforcing layer, a crystalline PPS fiber (denier: 2.2 dtex (fiber diameter: 14.44 μm), fiber length: 60 mm, cross-sectional shape: circular cross section) manufactured by Toyobo Co., Ltd. was intertwined by needle rolling to produce a basis weight of 400 g. /m ² short fibers are not woven.

The filter layer, the support layer, and the reinforcing laminate layer were entangled by pin rolling and integrated, and heated and pressurized by a hot calender roll having a temperature of 120 ° C and a pressure of 35 kg/m ² from the side of the filter layer. Further, singeing treatment of the filtration layer was carried out to obtain a felt having a basis weight of 585 g/m ² and a thickness of 1.80 mm.

The measurement results of the obtained felt are summarized in Table 1.

(Comparative Example 4)

The filter layer, the support layer, and the reinforcing laminate layer were entangled by pin rolling and integrated, and heated and pressurized by a hot calender roll having a temperature of 100 ° C and a pressure of 35 kg/m ² from the side of the filter layer. Further, in the same manner as in Example 5, a felt having a basis weight of 585 g/m ² and a thickness of 1.80 mm was obtained in the same manner as in Example 5 except that the singeing treatment of the filtration layer was carried out.

The measurement results of the obtained felt are summarized in Table 1.

As can be seen from the results of Table 1, it can be said that the nonwoven fabric used in the filter materials of Examples 1 to 4 is optimized by the appropriate heating and pressure treatment, and the surface morphology of the filter material is optimized, the filtration performance is improved, and the outlet dust concentration after the load is low. The value of the residual pressure loss after the load/initial value is small, that is, the non-woven fabric used for the filter material having a long life with little change in filtration performance. On the other hand, the nonwoven fabric used for the filter materials of Comparative Example 1 to Comparative Example 2 was not properly heated and pressurized, so that the surface morphology of the filter material was not optimized, and as a result, it was used as a filter material having poor performance as compared with the present invention. Not woven. The felt of Comparative Example 3 which does not contain the amorphous PPS fiber is treated in the same manner as in the present invention, although the heat treatment and the pressure treatment are the same as those of the present invention, but the result is that the filter material having poor performance is superior to the product of the present invention because 100% of the crystalline PPS fiber is used. Non-woven fabric used.

(industry availability)

The non-woven fabric used for the filter material of the present invention has no dust clogging, is excellent in dust turbulence, and can be used for long-term stable filtration of dust in the exhaust gas, and is preferably used for filtering. The non-woven fabric of the bag has a great contribution to the industry.

Claims (7)

A non-woven fabric for a filter material comprising 20% by mass to 100% by mass of amorphous polyphenylene sulfide fibers and 0% by mass to 80% by mass of heat resistant fibers, and having a basis weight of 80 g/m ² to 400 g/m. ^In the non-woven fabric of ² , the initial outlet dust concentration obtained by the German Institute of Engineers is 1.5 mg/m ³ or less, and the residual pressure loss after the load obtained by the German Institute of Engineers/initial residual pressure loss is 2.5 or less. The non-woven fabric used for the filter material according to claim 1, wherein the amorphous polyphenylene sulfide fiber has a fineness of from 1 dtex to 25 dtex and a fiber length of from 30 mm to 90 mm. The non-woven fabric for use in the filter material according to claim 1 or 2, wherein the heat-resistant fiber comprises a material selected from the group consisting of crystalline polyphenylene sulfide fibers, aromatic polyamide fibers, fluorine fibers, polyimine fibers, carbon fibers, and glass fibers. More than one fiber. A felt comprising a non-woven fabric for a filter material according to any one of claims 1 to 3 as a filter layer, and integrated with a support layer and a reinforcing layer. A filter using the felt as recited in claim 4 is used. A method for producing a non-woven fabric for a filter material, which is a short-fiber nonwoven fabric comprising 20% by mass to 100% by mass of amorphous polyphenylene sulfide fibers and 0% by mass to 80% by mass of heat-resistant fibers, by heating and adding The partial cross-sectional shape of the amorphous polyphenylene sulfide fiber is deformed into a flat cross section by pressure treatment, and/or film formation by melting. The method for producing a nonwoven fabric for use in a filter material according to claim 6, wherein the heating and pressurizing treatment is carried out at a temperature of from 110 ° C to 190 ° C and a pressure of from 20 kg/m ² to 50 kg/m ² .