JP2008179938A - Felt for filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a felt comprising polyphenylene sulfide fibers which is used as a bag filter, etc., by which the filter can stably filter dust discharge gas over long, improves the elasticity of the filter, and hence enables vibrational force to be efficiently propagated when the surface dust is removed by back washing and vibration. <P>SOLUTION: The filter felt is characterized by comprising at least one layer of a nonwoven fabric comprising 30% or more of hollow polyphenylene-sulfide short fibers having a percentage of hollowness of 5-50%, specific volume of 50 cm<SP>3</SP>/g or higher, and compressibility of 75% or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a felt used for a bag filter containing polyphenylene sulfide fiber, etc., and can perform dust filtration in exhaust gas stably for a long period of time, and by improving the elasticity of the filter, by backwashing and vibration The present invention relates to a felt for a filter that can efficiently transmit vibration force when removing dust on the surface.

  Exhaust gas discharged from coal-fired boilers, municipal waste incinerators, industrial waste incinerators, etc. contains not only soot dust but also harmful substances such as dioxins, and various exhaust gas dust collection is very important to prevent air pollution It is. In addition, exhaust gas filtration using a bag filter is highly expected from the viewpoint of dioxin production suppression and emission suppression. Moreover, if low pressure loss operation without clogging can be performed at a high filtration rate, the filtration area and bag filter installation area can be reduced, leading to cost reduction. Moreover, gasification melting furnaces and ash melting furnaces are used as countermeasures against harmful substances such as dioxins and heavy metals, and dust tends to become smaller.

Various methods have been studied as methods for performing exhaust gas filtration with a small amount of dust leakage and stable for a long period of time.
For example, as existing products, a membrane made of polytetrafluoroethylene (hereinafter referred to as “PTFE”) with a pore size of about 2 to 3 μm is adhered to the filtration surface side of a nonwoven fabric or woven fabric to improve the removal property. There is something that let me.
In addition, a filter cloth (for example, Patent Document 1) is proposed in which a uniaxially stretched film with slits in the film stretching direction is bonded to the filtration surface side of a nonwoven fabric or woven fabric to capture minute particles of the order of μm. ing.
For felts made of polyphenylene sulfide (hereinafter referred to as “PPS”) fibers, a fineness fiber is used for the filtration surface layer and a thickness gradient is applied (for example, Patent Document 2), and a modified cross-section fiber. The thing (for example, patent document 3) which enlarged the fiber surface area by using is known.

  When the above PTFE membrane is bonded to the filtration surface of the filter cloth, the dust jet-off property by the pulse jet method or the back washing method is excellent, but the pressure loss is large from the initial stage, and the adhesiveness to other materials is inferior. PTFE has a problem that the PTFE membrane itself peels off from the filtration surface due to dust removal operation over a long period of time, or dust is removed and wrinkles are caused by bending fatigue, resulting in breakage. The felt for bag filters also has a function of reacting and removing acidic gas such as hydrogen chloride with slaked lime in the cake layer on the filtration surface simultaneously with filtration. However, if a membrane is used, the cake layer is wiped off, so that there is a problem that the acid gas removal rate decreases. Furthermore, the cost of membrane processing is very high, and it is the highest as a filter cloth for bag filters.

  Although the thing of patent document 1 can capture the dust which tried to pass through the filter cloth with the film inside the filtration layer, since the porosity of the filtration layer itself made of fibers is large, it causes clogging and is stable for a long time. There is a problem that exhaust gas filtration cannot be performed.

  The thing of the patent document 2 has distribute | arranged the PPS short fiber whose fineness is 2.0 dtex or less to the filtration layer surface layer. Although this improves filtration performance, there is a problem that productivity at the time of creating felt is lowered.

  Moreover, in patent document 3, a fineness is 5.6 dtex or less, and a Y-type atypical cross-section PPS fiber is used and a performance improvement is carried out. However, even though these techniques can improve the filtration performance of the filtration layer, there is a problem in that the strength is greatly reduced due to the cross-sectional shape.

JP-A-2-253814 Japanese Patent Laid-Open No. 10-165729 Japanese Patent Laid-Open No. 2000-117027

  The present invention is capable of performing dust filtration in exhaust gas stably for a long period of time in a felt used for a bag filter containing PPS fibers, etc., against the problems of the above-described bag filter felt of the prior art, and the elasticity of the filter. It is an object of the present invention to provide a filter felt that can efficiently transmit vibration force when removing dust on the surface by pulse, backwashing, and vibration.

That is, the present invention is as follows.
1. At least one or more layers of non-woven fabric using hollow cross-sectional polyphenylene sulfide short fibers having a hollow ratio of 5 to 50%, a specific volume of 50 cm ³ / g or more, and a compression ratio of 75% or less are used. Filter felt.
2. The felt for felts according to claim 1, wherein the hollow cross-sectional polyphenylene sulfide short fiber is a hollow irregular cross-sectional polyphenylene sulfide short fiber having a cross-sectional shape in which at least two protrusions are present.
3. 2. The filter felt according to claim 1, wherein the polyphenylene sulfide short fibers have a specific volume of 70 cm ³ / g or more and a compressibility of 65% or less.
4). The filter felt according to any one of claims 1 to 3, wherein the polyphenylene sulfide short fibers have steric crimps.

  According to the present invention, a bag filter felt made of a nonwoven fabric layer containing PPS fibers can stably perform dust filtration in exhaust gas for a long period of time. By improving the elasticity of the filter, pulse, backwash, vibration Thus, it is possible to provide a filter felt that can efficiently transmit vibration force when removing dust on the surface.

Hereinafter, the present invention will be described in detail.
The cross-sectional shape of the PPS short fiber used in the present invention is preferably a hollow cross section, and the hollow ratio is preferably 5 to 50%, more preferably 10 to 40%. If the hollow ratio is less than 5%, sufficient specific volume and compression rate cannot be obtained, and if it exceeds 50%, a rupture problem occurs in the subsequent process. As a result, a sufficient specific volume and compressibility cannot be obtained.

  In the fiber cross-sectional shape, it is preferable that 2 to 5 protrusions are present, and more preferably 3 to 5 protrusions are present. Although the object can be achieved even if there are six or more protrusions, the effect is reduced unless the protrusions are made large. The presence of protrusions can reduce the compression rate.

Specific volume of PPS staple fibers used in the present invention is preferably at least 50 cm ³ / g, more preferably at least ^{60cm 3 / g, 70cm 3 /} g or more, and most preferably at least 90cm ³ / g. The compression rate is preferably 75% or less, more preferably 65% or less, and still more preferably 60% or less. If the specific volume is 50 cm ³ / g or less, or the compression ratio is 75% or more, a soft, so-called waist is obtained when the PPS short fiber is made into a felt entangled with a web using a needle punch or the like and maintains a certain volume. It becomes a felt with no vibration and absorbs the vibration force, and the vibration force cannot be transmitted efficiently.

  Furthermore, it is preferable that the crimp form has a three-dimensional crimp. This is because a desirable specific volume and compressibility can be obtained more easily than mechanical crimping.

  The fineness of the PPS short fibers is 2.0 to 20 dtex, preferably 2.5 to 17 dtex. If it is less than 2.0 dtex, the compression rate is increased, which is not preferable. On the other hand, if it exceeds 20 dtex, there is a problem that the cooling rate of the fiber at the time of production becomes slow and the productivity deteriorates.

Next, the resin used for obtaining the PPS short fibers will be described. The resin used is preferably a linear PPS polymer, and more preferably a melt flow rate of PPS measured by ASTM D-1238-82 under the conditions of a load of 49 N and a temperature of 315.6 ° C. is 50 to 160 g / 10 min. For various severe applications such as felts for bag filters, it is necessary to have not only mere heat resistance and chemical resistance, but also strength necessary for filter shapes, for example. Therefore, for example, in order to obtain high strength as a fiber, unreacted chlorine groups are left using trichlorobenzene or the like in the polymerization stage, and untreated by high-temperature treatment in an oxygen atmosphere or nitrogen atmosphere in the polymer stage before spinning. There is a method in which a crosslinking reaction is caused by a reactive chlorine group to increase the degree of polymerization and to obtain the initial strength necessary for the fiber. Further, even for a polymer having a relatively low melt flow rate (low molecular weight), the fiber itself can satisfy the required physical properties such as strength by temporarily crosslinking in an oxygen atmosphere and increasing the molecular weight before spinning. However, in such a method, a relatively low molecular weight polymer is a fiber made of a polymer obtained by a primary crosslinking reaction, and when a bond centered on a sulfur atom is measured by ESCA or the like, -SO- or -SO ₂ is already present. In such a method in which a bond of-is included and the degree of polymerization is primarily increased by crosslinking or oxidation, heat resistance over a long period cannot be obtained. The PPS of the present invention is obtained by spinning a linear polymer having a PPS melt flow rate of 50 to 160 g / 10 min measured by ASTM D-1238-82 under a load of 49 N and a temperature of 315.6 ° C. Yes, for example, when a bonding state centered on a sulfur atom is measured by ESCA, 95 atomic% or more is preferably a sulfide bond, 98 atomic% or more is more preferably a sulfide bond, and 100 atomic% is More preferably, it is a sulfide bond.

  The polyarylene sulfide represented by PPS in the present invention is an aromatic polymer having an arylene sulfide represented by —Ar—S— (Ar is an arylene group) as a repeating unit. As the arylene group, various things such as m-phenylene and naphthylene groups are known in addition to p-phenylene, but repetitive p-phenylene sulfide is also mentioned from the viewpoint of heat resistance, workability, and economy. The unit is the best.

  The melt flow rate measured by the PPS ASTM D-1238-82 method under the conditions of a load of 49 N and a temperature of 315.6 ° C. is 50 to 160 g / 10 min. In order to obtain sufficient long-term heat resistance and strength, a linear polymer and a higher degree of polymerization are preferred. However, if the melt flow rate is 50 g / 10 min or less, the viscosity is too high even at high temperatures, which is not preferable in terms of productivity because of an increase in pressure loss during spinning. In addition, when the melt flow rate is 160 g / 10 min or more, that is, when the molecular weight is small, an increase in pressure loss during spinning can be suppressed, but the molecular weight distribution becomes large and a higher molecular weight polymer is contained in a low pressure loss state. Further, the molten state of the high molecular weight polymer is poor, and there is a possibility of affecting the yarn breakage during spinning. Also, lowering the molecular weight is not desirable from the viewpoint of long-term heat resistance. From such a viewpoint, the melt flow rate of PPS is in the range of 50 to 160 g / 10 min, more preferably 80 to 140 g / 10 min. In addition, the linear polymer PPS is excellent not only in long-term heat resistance but also in heat stability at the time of melting, as compared with cross-linked or semi-cross-linked PPS.

  The PPS used in the present invention can be obtained by a polymerization reaction of an alkali metal sulfide and a dihaloaromatic compound in a polar organic solvent. As the alkali metal sulfide, for example, sodium sulfide, lithium sulfide, potassium sulfide, or a mixture thereof can be used. Among these, sodium sulfide is generally used because it is the most economical.

  Examples of the dihalo compound include dihalobenzenes such as p-dichlorobenzene, o-dichlorobenzene and m-dichlorobenzene, dihalonaphthalenes such as 1,4-dichloronaphthalene, other dihalobenzoic acid, dihalobenzophenone, di Although halophenyl ether etc. can be raised, p-dichlorobenzene is most preferably used from a physical property and an economical viewpoint. In addition, in general, it is also known to use a small amount of a polyhaloaromatic compound having 3 or more halogen substituents instead of 2 molecules per molecule in order to obtain a somewhat branched structure. As mentioned above, the linear polymer in the present invention is substantially free of such a semi-crosslinked structure.

Next, a method for obtaining the hollow cross section and the hollow modified cross section PPS fiber of the present invention will be described. It can be obtained by the melt spinning method using the aforementioned resin. It is extruded from a nozzle and spun at a speed of 500 to 2000 m / min to obtain an undrawn yarn. At this time, by using the nozzle having the nozzle holes of FIGS.
However, in order to obtain a three-dimensional crimp, it is necessary to give a difference in shrinkage rate in the yarn cross-sectional direction. As a method for producing such an undrawn yarn, the quench wind speed is set to 1.2 m / sec or more, preferably 1.6 m / sec or more, the cooling rate of the molten polymer is changed, and the melt flow rate is changed side by side. Is a method using a resin that is at least 10 g / 10 min, preferably 20 g / 10 min or more, a method in which the residence time of one polymer is increased by 0.5 minutes or more by side-by-side, a cross-linking type to one polymer by side-by-side Alternatively, a method using a semi-crosslinked resin, a method in which 0.1 to 50 wt%, preferably 1 to 20 wt% of polyketone sulfide, PEEK or the like, which is compatible with one side by side by side, is mixed by side by side. Incompatible with Fin resin (e.g. polypropylene) and 0.1-5 wt%, and the like preferably a method of mixing 0.2~2wt%. The undrawn yarn obtained as described above can be drawn by setting the draw ratio so as to have a desired fineness by a conventional method, drawn, dried and cut to obtain short fibers. At this time, in order to develop a three-dimensional crimp due to shrinkage, it is desirable to stretch the film under a temperature condition of 140 ° C. or higher, preferably 160 ° C. or higher, more preferably 180 ° C. or higher.

  The vibration force is filtered by using at least one layer of a non-woven fabric containing at least one kind of hollow cross-section and hollow modified cross-section PPS fibers obtained as described above, preferably at least 50%, more preferably at least 80%. A filter felt that can be efficiently transmitted to the surface can be obtained. For example, in general felts for bag filters, for example, PPS short fibers excellent in heat resistance and chemical resistance are used, but the structure is composed of a filtration layer, a support layer, and a clean gas side layer. There are many cases. In order to increase the surface area of the fiber, the filtration layer (outermost layer) often uses a fiber having a round cross section of 4 dtex or less, or a fiber having an irregular cross section such as a Y cross section or a flat cross section. In many cases, a woven fabric made of PPS fibers is used for the support layer in order to improve the dimensional stability at high temperatures. The clean gas side layer often uses round cross-section fibers of 2.2 dtex or more.

  The filter felt of the present invention can exert its effect particularly when used in the clean gas side layer opposite to the filtration layer. Therefore, the bag filter felt preferably has a two-layer structure or more of the felt layer of the present invention and a felt layer that is a filtration layer that is thinner than the fibers constituting the felt of the present invention and has a density 1.2 times higher. .

  In addition to PPS fibers, m-aramid fibers, polyimide fibers, PTFE fibers, and the like can be used in combination in the filtration layer, the support layer, and the clean gas side layer as required. However, from the viewpoint of processing after collection, it is preferable to be composed of 100% PPS fiber.

  The above felt can be obtained by laminating card webs and interlacing them with a needle punch. At this time, the filtration layer needs to be finished to a certain density or more in order to increase the filtration efficiency, but the clean gas side layer requires a certain volume or more according to product specifications. At this time, in the case of a fiber having a low specific volume or a fiber having a high compression rate, as described above, the felt does not have a waist and becomes a very soft product. The problem at this time will be described with an example of a bug filter. As for the pulse jet type of the bag filter, for example, a filter cloth having a cylinder diameter of 155φ and a length of 6 m is used in units of several tens of thousands for a small facility and tens of thousands for a large facility such as a thermal power plant. For the cylindrical filter cloth, gas flows from the outside to the inside of the filter, and the dust removal operation is repeated by a physical impact by the upper pulse air at a constant pressure and for a certain time. However, if the felt of the clean gas side layer is not elastic, the shock will be absorbed and the dust will not be able to be removed sufficiently, which will require a long impact, which will increase the damage to the fiber and will be disadvantageous for long-term use . Therefore, the specific volume and compressibility of the fibers used for the clean gas side layer are important.

  The integration process of the filtration layer, the support layer, and the clean gas side layer can be performed by either a needle punch method or a water punch method. Moreover, you may perform a 140-270 degreeC heat press after lamination | stacking integration of a filtration layer, a support layer, and a clean gas side layer. Furthermore, after laminating and integrating the filtration layer, the support layer and the clean gas side layer and heat-pressing, after the heat treatment at 180 ° C. or higher, the filter surface layer is baked, or after the heat treatment at 180 ° C., filtration with an infrared ray or an electric heating bar is performed. Surface melting treatment can be performed. Alternatively, in order to further smooth the outermost surface of the filtration layer, a thermal calendar process can be performed after the hair baking process.

  In addition, fluorine-based resin processing can be performed after performing lamination and integration of the filtration layer, the support layer, and the clean gas side layer, hot pressing, heat treatment, felt surface treatment, and the like.

Hereinafter, the present invention will be described in detail using examples.
The measuring method is as follows.

Specific volume and compressibility: Evaluated in accordance with JIS L 1097 synthetic fiber futon test method. The card web is stacked so as to be about 5 g at 10 cm × 10 cm. After standing for 1 hour or more, the mass of the sample is accurately measured (Wg). A 60 g top plate is placed, a 500 g weight is placed for 30 seconds, only the weight is removed and left for 30 seconds. This operation is repeated three times, the weight is removed, and after 30 seconds, the heights of the four corners are measured to obtain an average value (H0 mm). A 60 g top plate is placed on the sample, and a 1000 g weight is placed for 30 seconds, and the heights of the four corners at this time are measured to obtain an average value (H1 mm).
Specific volume (cm ³ / g) = 10 × 10 × H0 / 10 / W
Compression rate (%) = (H0−H1) / H0 × 100

  Fineness: Measured according to the method of JIS L-1015-8.5 (1999).

Hollow ratio: The cross-section was photographed with an optical microscope and determined from the area ratio.
Hollow ratio (%) = Hollow area / Outer circumference area × 100

Dust removal by pulse air (German standard, VDI N3926):
Filtration rate: 2.0 mm / min, dust concentration: 5 g / m ³ , dust type: Pural NF, temperature: 130 ° C., dust removal: 1000 Pa, aging interval: 5 s, tank pressure: 0.5 MPa, pulsed air pressure: 1017 mbar, pulse time: 60 ms
Procedure (1) At the stage where the sample is mounted, the initial pressure loss Pa of the sample felt is measured without dust.
(2) First stage: Dust is removed when the pressure loss reaches 1000 Pa. This operation is repeated 30 times.
(3) Second stage: aging is performed 10,000 times at intervals of 5 s without dust.
(4) Third stage: As a stabilizing operation, only a dusting-off operation with pulsed air is performed 10 times without dust.
(5) Fourth stage: Dust is flown, and dust is removed at a pressure loss of 1000 Pa for 2 hours. The residual pressure loss Pa immediately after dust removal is measured at the final time.

<Example 1>
PPS having a melt flow rate of 110 g / 10 min was extruded from the nozzle of FIG. 1 at a polymer temperature of 300 ° C. and discharged at a single hole discharge rate of 2.0 g / min and spun at 1200 m / min. The cooling conditions at this time were 1.6 m / sec and 25 ° C. Thereafter, the total fineness was 1,000,000 dtex, the drawing ratio was 2.5, the drawing temperature was 160 ° C., and after drying, cut to 64 mm to obtain hollow cross-section PPS short fibers. The fineness was 6.7 dtex, the hollow rate was 25%, the volume was solid, the specific volume was 98 cm ³ / g, and the compression rate was 71%. This fiber was used as a clean gas side layer card web (weight per unit area: 200 g / m ² ) at 100%. A web composed of 100% PPS (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) having a 2.2 dtex round cross-section fiber in advance is used as a support layer for a PPS woven fabric (500 dtex, plain fabric using 120 filament PPS long fibers, weaving density vertical / horizontal = 26/20 present per 2.54 cm, and laminated to the basis weight 104 g / ^{m 2),} was created filtration layer felt (basis weight 200 g / ^{m 2)} and the support layer of the laminate by needle punching. The card web for the clean gas side layer was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punch from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was burned with gas to obtain a bag filter felt having a basis weight of 521 g / m ² and a thickness of 1.8 mm. It was.

<Example 2>
A PPS polymer having a melt flow rate of 110 g / 10 min was extruded from the nozzle shown in FIG. 1 at a polymer temperature of 300 ° C. with a single hole discharge rate of 2.1 g / min and spun at 1200 m / min. The cooling conditions at this time were 3.0 m / sec and 25 ° C. Thereafter, the total fineness was set to 1,000,000 dtex, the film was drawn at a draw ratio of 1.8 and a drawing temperature of 160 ° C., dried and cut to 64 mm to obtain hollow cross-section PPS short fibers. The fineness was 14 dtex, hollow rate = 22%, solid crimp, specific volume = 90 cm ³ / g, compressibility = 65%. This fiber was used as a clean gas side layer card web (weight per unit area: 200 g / m ² ) at 100%. A web composed of 100% PPS (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fiber is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and a filter layer felt (weight per unit area) is obtained by needle punching. 200 g / m ² ) and a laminated product of a support layer were prepared. The card web for the clean gas side layer was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punch from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 530 g / m ² and a thickness of 2.1 mm. .

<Comparative Example 1>
A PPS polymer having a melt flow rate of 110 g / 10 min was extruded at a polymer temperature of 300 ° C. from a round nozzle at a single hole discharge rate of 2.1 g / min and spun at 1200 m / min. The cooling conditions at this time were 1.0 m / sec and 25 ° C. Thereafter, the total fineness was 1,000,000 dtex, the film was stretched at a stretching ratio of 2.5 and a stretching temperature of 160 ° C., crimped by a stuffing box, cut into 64 mm after drying, and round section PPS short fibers were obtained. The fineness was 7.0 dtex, mechanical crimping, specific volume = 65 cm ³ / g, compression rate = 65%. This fiber was used as a clean gas side layer card web (weight per unit area: 200 g / m ² ) at 100%. A web composed of 100% PPS (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fiber is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and a filter layer felt (weight per unit area) is obtained by needle punching. 200 g / m ² ) and a laminated product of a support layer were prepared. The card web for the clean gas side layer was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punch from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 515 / m ² and a thickness of 1.8 mm. .

<Example 3>
60% by weight of the 6.7 dtex hollow cross-section PPS short fiber obtained in Example 1 and 40% by weight of the 7.0 dtex round cross-section PPS short fiber obtained in Comparative Example 1 were mixed to obtain a clean gas side layer card. The web (weight per unit area: 200 g / m ² ) was used. A web composed of 100% PPS (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fiber is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and a filter layer felt (weight per unit area) is obtained by needle punching. 200 g / m ² ) and a laminated product of a support layer were prepared. The clean gas side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 530 / m ² and a thickness of 1.8 mm. .

<Comparative example 2>
A card for a clean gas side layer comprising 10% by weight of the 6.7 dtex hollow cross-section PPS short fibers obtained in Example 1 and 90% by weight of the 7.0 dtex round cross-section PPS short fibers obtained in Comparative Example 1. The web (weight per unit area: 200 g / m ² ) was used. A web composed of 100% PPS (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fiber is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and a filter layer felt (weight per unit area) is obtained by needle punching. 200 g / m ² ) and a laminated product of a support layer were prepared. The clean side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 505 / m ² and a thickness of 1.8 mm. .

<Example 4>
A PPS polymer having a melt flow rate of 110 g / 10 min was extruded from the nozzle shown in FIG. 5 at a polymer temperature of 300 ° C. with a single hole discharge rate of 2.7 g / min and spun at 1200 m / min. The cooling conditions at this time were 3.0 m / sec and 25 ° C. Thereafter, the total fineness was 1,000,000 dtex, the drawing ratio was 2.0, the drawing temperature was 160 ° C., and after drying, cut to 64 mm to obtain hollow irregular cross-section PPS short fibers. The fineness was 11 dtex, hollow rate = 22%, solid crimp, specific volume = 65 cm ³ / g, compression rate = 61%. This fiber was used as a clean gas side layer card web (weight per unit area: 200 g / m ² ) at 100%. A web composed of 100% PPS short fibers (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fibers is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and filtered by a needle punch. A laminate of a layer felt (weight per unit area: 200 g / m ² ) and a support layer was prepared. The clean side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 525 g / m ² and a thickness of 2.0 mm. .

<Comparative Example 3>
A PPS polymer having a melt flow rate of 110 g / 10 min was extruded from a round nozzle at a polymer temperature of 300 ° C. and discharged at a single hole discharge rate of 1.9 g / min and spun at 1200 m / min. The cooling conditions at this time were 1.0 m / sec and 25 ° C. Thereafter, the total fineness was 1,000,000 dtex, the film was drawn at a draw ratio of 2.2 and a drawing temperature of 160 ° C., crimped by a stuffing box, dried, and cut to 64 mm to obtain a round cross-section PPS short fiber. The fineness was 7.0 dtex, mechanical crimping, specific volume = 65 cm ³ / g, compression rate = 70%. This fiber was 100% to make a clean gas side layer card web of 200 g / m ² . A web composed of 100% PPS short fibers (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fibers is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and filtered by a needle punch. A laminate of a layer felt (weight per unit area: 200 g / m ² ) and a support layer was prepared. The clean side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 509 g / m ² and a thickness of 1.8 mm. .

<Example 5>
A clean gas side layer card web was prepared by blending 60 wt% of the 11 dtex hollow modified cross section PPS short fibers obtained in Example 4 and 40 wt% of the 7.0 dtex round cross section PPS short fibers obtained in Comparative Example 3. 200 g / m ² . A web composed of 100% PPS short fibers (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fibers is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and filtered by a needle punch. A laminate of a layer felt (weight per unit area: 200 g / m ² ) and a support layer was prepared. The clean side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 518 g / m ² and a thickness of 1.9 mm. .

<Comparative Example 4>
A clean gas side layer card web was prepared by blending 10 wt% of the 11 dtex hollow modified cross-section PPS short fibers obtained in Example 4 and 90 wt% of the 7.0 dtex round cross-section PPS short fibers obtained in Comparative Example 3. It was. This fiber was 100% to make a clean gas side layer card web of 200 g / m ² . A web consisting of 100% PPS short fibers (Procon (registered trademark) manufactured by Toyobo Co., Ltd.) with 2.2 dtex round cross-section fibers is laminated on a PPS base fabric similar to that in Example 1 by a cross layer, and a filter layer felt is formed by needle punching. A laminate of (a basis weight of 200 g / m ² ) and a support layer was prepared. The clean side card web was laminated on the support layer side (opposite side of the filtration layer) of this laminate, and further integrated by needle punching from both sides. The obtained felt was pressed and heat-set by a heat calendar at 210 ° C., and the filter layer was subjected to gas hair burning to obtain a bag filter felt having a basis weight of 501 g / m ² and a thickness of 1.9 mm. .

As described above, in the present invention, in order to improve the dust removing effect of filter felt that has been generally used in the past, the hollowness is 5 to 50%, the specific volume is 50 cm ³ / g or more, and compression is performed. By using at least one or more layers of non-woven fabric using 30% or more of hollow cross-section polyphenylene sulfide short fibers having a rate of 75% or less, the remaining rate could be efficiently reduced. Accordingly, it is possible to provide a felt for a filter that can increase the operation time of pulsed air or the like and can prolong the filter life.

It is an example which shows the nozzle for hollow cross-section fibers which can be used by this invention. It is an example which shows the nozzle for hollow cross-section fibers which can be used by this invention. It is an example which shows the nozzle for hollow cross-section fibers which can be used by this invention. It is an example which shows the nozzle for cross-sectional shape fibers which can be used by this invention and has two protrusions. It is an example which shows the nozzle for cross-sectional shape fibers which can be used by this invention and has three protrusions. It is an example which shows the nozzle for cross-sectional shape fibers which can be used by this invention and has four protrusions.

Claims (4)

At least one or more layers of non-woven fabric using hollow cross-sectional polyphenylene sulfide short fibers having a hollow ratio of 5 to 50%, a specific volume of 50 cm ³ / g or more, and a compression ratio of 75% or less are used. Filter felt.   The felt for felts according to claim 1, wherein the hollow cross-sectional polyphenylene sulfide short fiber is a hollow irregular cross-sectional polyphenylene sulfide short fiber having a cross-sectional shape in which at least two protrusions are present. 2. The filter felt according to claim 1, wherein the polyphenylene sulfide short fibers have a specific volume of 70 cm ³ / g or more and a compressibility of 65% or less. The filter felt according to any one of claims 1 to 3, wherein the polyphenylene sulfide short fibers have steric crimps.

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