JPH0716570B2 - Filter cloth with high collection efficiency and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, fibers in the absence relates filter cloth and a manufacturing method thereof with high shape retention and tensile strength when used in such a bag filter, the foreign substance which inhibits filtration performance intermediate Thickness gradually increases from the front to the back
The present invention relates to a filter cloth excellent in dust collection efficiency by being distributed in such a manner and a method for manufacturing the same.

[0002]

2. Description of the Related Art A bag filter is required to have a shape-retaining property and a tensile strength capable of withstanding a mechanical action of periodically removing dust adhering to a filter cloth for a long period of time. Woven cloth or felt is used for the filter cloth. In recent years, dye powder, talc, cement powder, etc. are often filtered as dust to be filtered, and the dust is gradually made finer, so that the conventional filter cloth can achieve a sufficient dust collecting effect. I can't.

[0003]

In response to this tendency of dust granulation, the surface of woven cloth or felt is coated with urethane foam or acrylic resin having open cells, or PTF.
The unfired film of E is laminated. However, in the former case, the pressure loss of the filter cloth is too high to obtain a sufficient dust collecting effect, while in the latter case, the dust releasability is good but the durability is poor.

It has been proposed to use a non-woven fabric sheet of microfibers or ultrafine fibers in order to further enhance the dust collection effect than before, but this non-woven fabric sheet is not so high in tensile strength, and as a single body, it is used in automobiles and the like. Only applicable to air filters. Recently, in order to improve the durability of this nonwoven sheet, the sheet may be laminated on the surface of a normal needle felt sheet. In this case, a heat-sealing film may be interposed between the non-woven sheet and the needle felt sheet, or the surface of the felt sheet may be mixed with heat-fusible fibers, both sheets may be polymerized, and then heat-melted by passing between heat rolls. The adhesive fiber is melted and adhered.

In the above-mentioned method, the melted heat-bonding film or heat-meltable fiber is interposed as a foreign substance between the non-woven sheet such as microfiber or ultrafine fiber and the needle felt sheet, and the obtained filtration cloth is filtered. It becomes a factor that hinders the performance. Further, the non-woven sheet and the needle felt sheet are completely separated by the heat-sealing film or the heat-sealable fiber, the amount of the heat-sealable film or the heat-sealable fiber used is small, or the melting is not complete. There is a risk of peeling during dust removal work.

The present invention has been proposed in order to improve the above-mentioned problems associated with conventional filter cloths used for bag filters and the like, and has high shape retention and tensile strength even after repeated dust-off operations. Moreover, it is an object of the present invention to provide a filter cloth having excellent dust collection efficiency and a method for producing the same.

[0007]

In order to achieve the above object, a filter cloth 1 according to the present invention has a relatively thin upper fine fiber layer 2 and a relatively thick lower fiber layer 2 as shown in FIG. And the felt base material layer 3. Both layers 2 and 3 are integrated by vertical needle punching, and the fibers of the fiber layer 2 and the base material layer 3 are entangled with each other. If desired, a small amount of heat-fusible fibers may be mixed in the lower part of the fiber layer 2 or the upper part of the base material layer 3 and then fused by calendering for finishing.

A sheet 4 to be the ultrafine fiber layer 2 (FIG. 1)
Is composed of fibers that can be divided into a large number in the longitudinal direction by a mechanical action such as a high-pressure water jet punch or a chemical treatment with a solvent, and it is also possible to mix ordinary fibers with the fibers. The fibers of the ultrafine fiber layer 2 generally have a denier of about 3 to 4 before processing and a denier of about 0.1 to 0.2 after processing. The unprocessed ultrafine fiber sheet 4 is, for example, a single-layer nonwoven fabric formed by a spunbond method, a melt-blowing method, or the like, or a multilayer nonwoven fabric or felt formed by laminating these nonwoven fabrics.

The sheet 5 (FIG. 1) to be the felt base material layer 3 has a porosity larger than that of the fiber layer 2 after processing,
The filter cloth 1 may be of any type as long as it has sufficient tensile strength. Generally, a known needle felt such as polyester fiber or polyamide fiber is used for the sheet 5. When used in a bag filter or the like, it is preferable to interpose a base fabric 6 such as a plain woven fabric in the middle of the sheet 5 in order to obtain high shape retention and tensile strength.

In order to manufacture the filter cloth 1 of the present invention, the raw ultrafine fiber sheet 4 and the felt base sheet 5 are polymerized, and both sheets 4 and 5 are integrated by vertical needle punching. (See Figure 2). By this needle punching, ultrafine fibers 7 (Fig. 4) or 8
(FIG. 5) is distributed while gradually decreasing from the front surface to the back surface in the filter cloth 1. The ultrathinnable fibers in the integrated sheet are longitudinally divided into a large number by mechanical action such as a high-pressure water jet punch or chemical treatment with a solvent.

The ultra-thinnable fibers 7 of about 2-3 denier illustrated in FIG. 4 become, for example, 8 or 16 along a predetermined longitudinal line 9 when a mechanical action such as a high-pressure water jet is applied. It will be divided into about 0.1-0.2 denier. Further, in the ultrafine fiber 8 shown in FIG. 5, the soluble portion 10 is dissolved by the chemical treatment with the solvent, and the fiber 11 having about 0.1 to 0.2 denier is separated into a large number in the longitudinal direction. Finally, the filter cloth 1 is calendered between appropriate rolls 12 and 12 and dried, and the surface is flattened to adjust the thickness.

[0012]

The filter cloth 1 of the present invention has no foreign matter between the ultrafine fiber layer 2 and the felt base material layer 3 which hinders the filtration performance.
Distribution that the fiber thickness gradually increases from the front surface to the back surface
Since the are collecting efficiency of the dust is high. Further, the ultrafine fiber layer 2 and the felt base material layer 3 are almost completely integrated by needle punching in the vertical direction, and the relatively weak ultrafine fiber layer 2 is reinforced by the felt base material layer 3 to maintain a high form. It possesses good properties and tensile strength.

Further, in the method of the present invention, the ultrafine fiber 7 or 8 is not yet ultrafine when the sheets 4 and 5 are integrated by needle punching, and maintains a fineness similar to that of a normal fiber. Therefore, the needle punching rarely cuts.

[0014]

EXAMPLES Next, the present invention will be explained based on examples. Examples 1 and 2 As the felt substrate sheet 5, a web composed of 50% polyester fibers having an average fineness of 2 denier and 50% polyester fibers having an average fineness of 3 denier is used. In the middle of this web, a plain woven base fabric 2 made of polyester filament of 200 denier and having a size of 25 × 20 filaments / inch was interposed, and a basis weight was 300 g / by needle punching.
obtaining a felt base sheet 5 of the m ^2.

On the other hand, as the ultrafine fiber sheet 4,
A 2-denier 16-division type fiber (trade name: Tylylin, made by Nanya Plastics) made of polyamide / polyester is used.
An ultrafine fiber sheet 4 of 0 g / m ² is obtained. As shown in FIG. 1, the ultrafine fiber sheet 4 is superposed on the felt base sheet 5 and integrated by vertical needle punching, whereby the ultrafine fiber layer 2 and the felt base layer 3 are integrated. Intertwining the fibers in.

Next, the surface of the integrated sheet is treated with a high-pressure water jet punch of the same pressure three times to divide the ultrafine fiber 7 (FIG. 4) into fine pieces, and then the sheet is dried. Calendar processing is performed between the rolls 12 and 12. As a result, in the obtained filter cloth 1, the distribution of the ultrafine fibers gradually decreases from the front surface of the sheet toward the back surface. Filter cloths 1 shown in Table 1 below are obtained according to the conditions of the high-pressure water jet punch.

[0017]

[Table 1]

The performance of the filter cloths obtained in Examples 1 and 2 was
Known with needle felt made of polyester fiber
The results are shown in Table 2 below in comparison with the filter cloth. This ratio
For the comparison test, talc with a particle size of 9.7 μm was used as the powder.
(Corresponding to JIS 4 types), F = 1.5m³/ M²・ Minute, F = 2.
0m³/ M²・ Minute, F = 2.5m³/ M In 2 minutes,
It runs for 8 hours each with a loss interval of 14 seconds.

The measurement unit is pressure loss: mmH ₂ O, outlet concentration: mg / m ³ , collection efficiency:%, and the outlet concentration is measured by a dust tube method.

[0020]

[Table 2]

The filter cloths of Examples 1 and 2 have a higher collection efficiency than the conventional filter cloths having a high basis weight. Further, since the filter cloth of the present invention has good dust releasability, there is no large difference in pressure loss, and it is suitable for bag filters and the like.

Example 3 The felt base material sheet 5 is the same as in Example 1, and as the ultrafine fiber sheet 4, 2 denier 16 division type fibers made of polyamide / polyester (trade name: Tyrylline, manufactured by Nanya Plastic Co., Ltd.) ) 30% and 6.7 denier Teflon fiber (trade name: Toyofuron, Showa Kogyo)
A felt having a basis weight of 150 g / m ² consisting of 70% is used. The ultrafine fiber sheet 4 is polymerized on the felt base sheet 5, and then treated in the same manner as in Example 1 to obtain the filter cloth 1.
To get

The filter cloth of Example 3 has a high collection efficiency similar to that of Example 1. In addition, the filter cloth of Example 3 has better dust releasability and a pressure loss of 120.
It does not exceed mmH ₂ O.

Example 4 As the felt base sheet 5, a web made of 100% of 3 denier polyamide fiber is used. In the middle of this web, a plain woven base fabric 2 made of polyamide filament of 200 denier and having an injection rate of 20 × 18 fibers / inch is interposed, and a basis weight of 300 g / is obtained by needle punching.
obtaining a felt base sheet 5 of the m ^2. On the other hand, the ultrafine fiber sheet 4 is the same felt as in Example 1. The ultra-thinnable fiber sheet 4 is polymerized on the felt base sheet 5, and they are integrated by needle punching in the vertical direction.

Next, the integrated sheet is treated with 3% NaOH.
After being immersed in the solution, boiled for 20 minutes, washed with water and dried to divide the ultrafine fiber 8 (FIG. 5) into a large number of fibers 11, calendering is further performed between the rolls 12 and 12. As a result, in the obtained filter cloth 1, the distribution of the ultrafine fibers gradually decreases from the front surface of the sheet toward the back surface. The filter cloth of Example 4 also has a high collection efficiency as that of Example 1.

[0026]

INDUSTRIAL APPLICABILITY The filter cloth of the present invention is free from foreign substances such as a heat-sealing film, a heat-sealing fiber or an adhesive which hinders the filtration performance between the ultrafine fiber layer and the felt base material layer. , Fiber
Is distributed so that the thickness of the
As a result, the dust collection efficiency is high. In the method of the present invention, the ultrafine fiber-capable sheet and the felt substrate sheet are entangled with each other by needle punching in the vertical direction so that the whole is almost completely integrated, so that it is separated into two layers even if the dust removing operation is repeated. There is no fear that it retains high shape retention and tensile strength even after long-term use.

Further, in the method of the present invention, the ultrafine fiber is not ultrafine when integrated by vertical needlepunching, and has the same fineness as ordinary fiber. It is rarely cut off. In the method of the present invention, after needle-punching in the vertical direction, the ultrafine fiber is divided into a large number in the longitudinal direction by a mechanical action such as high-pressure water jet punching or a chemical treatment with a solvent. On the other hand, it is possible to surely obtain fine pores by the ultrafine fibers.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an ultrafine fiber sheet and a felt substrate sheet used in the present invention.

FIG. 2 is a schematic cross-sectional view showing a state in which a polymerized ultrafine fiber sheet and a felt substrate sheet are integrated by needle punching.

FIG. 3 is a schematic side view illustrating the finishing process of the filter cloth according to the present invention.

FIG. 4 is an enlarged cross-sectional view showing an example of ultrafine fiber that can be used in the present invention.

FIG. 5 is an enlarged cross-sectional view showing another example of ultrafine fiber.

[Explanation of symbols]

 1 Filter cloth 2 Ultrafine fiber layer 3 Felt base material layer 4 Ultrafine fiber sheet 5 Felt base material sheet 6 Base cloth

Claims (3)

[Claims] 1. A relatively thin upper ultrafine fiber layer and a relatively thick lower felt base material layer, wherein the ultrafine fiber layer is suspended.
Directly needle punching with the fibers of the felt base layer
By the ultrafine processing of the ultrafine fibers that are entangled with each other
Consists divided fibers, fiber after the microfine treatment
The thickness of the fibers is distributed so that it gradually increases from the front surface to the back surface.
And that the collection efficiency of the high filtration cloth. 2. A raw ultrafine fiber sheet and a felt base sheet are polymerized, and the two sheets are integrated by vertical needle punching to gradually reduce the distribution of the ultrafine fiber from the front surface to the back surface. , Then, by using a high-pressure water jet punch, the fibers can be divided into fine particles by dividing them into fine particles,
A method for manufacturing a filter cloth, which comprises calendering between rolls for finishing. 3. A raw ultrafine fiber sheet and a felt base sheet are polymerized, and both sheets are integrated by vertical needle punching to gradually reduce the distribution of the ultrafine fiber from the front surface to the back surface. Then, a method for producing a filter cloth, in which the ultrafine fiber is divided into ultrafine fibers by treating the ultrafine fiber with a solution in which the ultrafine fibers are partially dissolved, and then calendered between rolls to finish.