JPH08192018A - Filter cloth with improved durability - Google Patents

Abstract

PURPOSE: To attain not only excellent heat resistance and inflammability but excellent strength and chemical resistance, to increase the air permeability of a filter cloth and to reduce the increase of air permeable resistance caused by the clogging or dust after being used for a long term by using a polyphenylenesulfide fiber for a reinforcing base cloth of a felt. CONSTITUTION: In the filter cloth composed of a metal-aramid fiber felt, the polyphenylenesulfide fiber is used for the reinforcing base cloth of the felt. Using the polyphenylenesulfide fiber for the reinforcing base cloth for the felt means using a fiber composed substantially of the polyphenylenesulfide as the base cloth. The single fiber fineness of the polyphenylenesulfide fiber is preferably 1.5-5.0 denier, more preferably 1.5-2.0 denier. The yarn of the polyphenylenesulfide fiber is constituted of a single fiber of 50-2000, preferably 500-1000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a dust collecting filter cloth, particularly 12
The present invention relates to a filter cloth for dust collection which is excellent in chemical resistance when used at a relatively high temperature of 0 to 180 ° C.

[0002]

2. Description of the Related Art A bag filter is a dust collector using a filter cloth. The bag filter collects dust by suspending a cylindrical, envelope or flat filter cloth in the dust collecting chamber. Dust adhering to the filter cloth is removed from each chamber, and dust collection and removal are repeated to enable long-term dust collection. Filter cloths for bag filters are roughly classified into two types, woven cloth and non-woven cloth such as needle punched felt. Of these, the base cloth and felt of the non-woven cloth are made of aramid fiber from the viewpoint of heat resistance. Has been used.

For example, "a filter cloth for dry use, in which felt made of wholly aromatic polyamide resin fibers is set under pressure at a temperature not lower than the glass transition point of the resin" (Japanese Patent Laid-Open No. 58-8531).
Gazette) "Heat-resistant filter material using a crystalline complex obtained by contacting an aromatic polyamide in which at least 75 mol% of repeating structural units are m-phenyleneisophthalamide with an organic solvent as a bonding material" (JP-A-58). -8531
Gazette) "Air filter for high temperature, characterized in that the fibers of a filter made of heat-resistant fiber are adhered to each other by a polysiloxane compound" (JP-A-60-8782).
No. 2) and the like are disclosed.

As aramid, there are a so-called para type such as polyparaphenylene terephthalamide (PPTA) and a so-called meta type such as polymetaphenylene terephthalamide (PMIA). Conventionally, at a relatively high temperature of 120 to 200 ° C. In this case, as the non-woven fabric, a yarn (yarn) of 100% meta-aramid fiber is generally used for both the base fabric and the felt. However, the exhaust gas is 30-5
Containing 0% by volume of water, HCl, Sox, N
If there is a large amount of acid gas such as ox, or if Ca is present in the piping until it reaches the dust collector for the purpose of acid gas removal.
When (OH) ₂ or the like was added, meta-aramid was weak against these chemicals and had a problem in durability.

[0005]

The object of the present invention is to provide not only heat resistance and flame retardancy required for a filter cloth, but also excellent strength and chemical resistance. Further, the air permeability of the base cloth is increased, and the cloth is used for a long time. Another object of the present invention is to provide a durable filter cloth in which an increase in ventilation resistance due to clogging of dust is reduced.

[0006]

That is, the present invention provides: ((Claim 1) A filter cloth comprising a meta-aramid fiber felt, wherein a polyphenylene sulfide fiber is used as a base cloth for reinforcing the felt, and the filter cloth has improved durability. It is.

The use of polyphenylene sulfide fiber for the reinforcing base fabric of the felt means to use a fiber consisting essentially of polyphenylene sulfide as the base fabric. For example, a fiber made of a copolymer of 80% polyphenylene sulfide may be used, or a mixed yarn of a fiber made of 100% polyphenylene sulfide and another fiber may be used. “Substantially” is a range in which the mixing ratio of polyphenylene sulfide is capable of exhibiting the effects of the present invention. The meta-type aramid is an aromatic ring having an amide bond at the meta position. A typical example is polymetaphenylene isophthalamide, and Conex (manufactured by Teijin Limited), Nomex (manufactured by Deyupon Corporation) and the like are commercially available. A copolymer in which 80% or more of the repeating units are amide-bonded at the meta position is also included.

Polyphenylene sulfide is a compound in which aromatic rings are bound to each other in the para-position. Teijin PPS and the like are commercially available products. A copolymer in which 80% or more of the repeating units are sulfide-bonded at the para position is also included.

The single yarn fineness of the polyphenylene sulfide fiber is preferably 1.5 to 5.0 denier, more preferably 1.5 to 2.0 denier. Single yarn fineness is 1.
When it is less than 5 denier, the strength of the single yarn varies and sufficient tenacity cannot be exhibited when the yarn is formed. When the single yarn fineness exceeds 5.0 denier, the fibers become hard, and the filter cloth formed by using the base cloth made of polyphenylene sulfide fibers also becomes hard, so that the removal performance is deteriorated.

The polyphenylene sulfide fiber yarn (yarn) is 500 to 2000, more preferably 500.
It is composed of 1000 single yarns. The number of fiber yarns is 50
If the number is less than 0, strong expression will be insufficient. If the number of fiber yarns exceeds 2000, the fiber yarns become hard and the filter cloth formed by using the base cloth made of polyphenylene sulfide fiber also becomes hard, so that the removal performance is deteriorated.

The base fabric is a woven fabric, a knitted fabric, a non-woven fabric, or
A mixture of these may be used, but a woven fabric is preferable in view of the required characteristics of the filter cloth. When a woven fabric is used, it is preferable that the yarn is woven at a density of 5 to 15 yarns / inch each to form a base fabric. A plain weave, a twill weave, a multiple weave, or the like can be used for weaving, but a plain weave is preferable in view of the required characteristics of the filter cloth. If the density of the base cloth is increased too much in order to increase the durability of the filter cloth, the ventilation resistance is increased, which causes clogging of dust due to long-term use. The base cloth density is designed according to the purpose of use so that durability and ventilation resistance are practically compatible with each other.

A conventional base cloth composed of 100% of meta-aramid fiber has a weft density of 15 to 20 fibers / inch, and the polyphenylene sulfide fiber is more preferable in terms of ventilation resistance and This is advantageous from the viewpoint of preventing clogging.

As a method of reinforcing the felt with a base cloth,
A method in which a nonwoven fabric (web) is entangled with a base cloth by needle punching is often used. In that case, the above-mentioned meta-aramid single fiber is used as the web. The single yarn fineness of the meta-aramid single fiber is preferably 0.8 to 5.0.
Denier, more preferably 0.8 to 2.0 denier. When the monofilament fineness of the meta-aramid single fiber is less than 0.8 denier, the entanglement by the needle punching cannot be sufficiently performed, and as a result, uneven weight is generated. When the single yarn fineness of the meta-aramid single fiber exceeds 5.0 denier, the dust collection performance of the filter cloth deteriorates.

The fiber length is preferably 38 to 103 mm,
More preferably, it is 51 to 76 mm. Fiber length is 38m
If it is less than m, entanglement by the needle punch becomes insufficient, and as a result, sufficient strength development cannot be achieved. If the fiber length exceeds 103 mm, it becomes difficult to align the fiber yarns when forming the web.

100% polyphenylene sulfide fiber
On both sides or one side of the base fabric consisting of, preferably on both sides,
Made from meta-type aramid short fibers by the needle punch method.
To form a fiber layer (web layer). Punching tight
300-500 times / cm ²Is preferred. In addition,
Burning with a burner on one side of the fiber layer (web layer)
Or surface smoothing with a calendar
Is preferred.

[0016]

The filter cloth of the present invention is suitable for use at a high temperature, for example, at 120 to 200 ° C. The base fabric is much stronger than conventional products and can be used for a long period of time. Furthermore, since the area occupied by the base cloth is smaller than that of the conventional product, ventilation resistance is small, and clogging of the base cloth due to dust after long-term use can be prevented, so that a filter cloth capable of maintaining a low pressure loss can be obtained. .

The present invention will be specifically described below with reference to examples. The characteristics of the obtained filter cloth were evaluated by the following methods.

<Tensile Strength> According to JIS-L-1096A. That is, using a constant-speed long-type tensile tester, gripping distance 10 cm, pulling speed 100 mm / min, width 2 c
A test piece of m and 20 cm in length was stretched to break.

<Acid resistance> 7% H _{2 in} a beaker that can be depressurized
An aqueous solution of SO ₄ is added, and the sample is completely immersed in the aqueous solution. Then, the inside of the beaker was depressurized with an aspirator or a vacuum pump for 1.5 hours to sufficiently impregnate the sample with sulfuric acid water, and then the sample was taken out and heat-treated at 150 ° C. for 1 hour, and then the strength retention was measured. .

<Filtration performance> Effective area is 30 cm × 30 c
m flat filter cloth sample was used. Filtration rate 2.0
m / min. The test powder (10 kinds of JIS standard dust) was filtered at a temperature of 200 ° C., and the time until the differential pressure before and after the filter reached the water column of 80 mm was measured. A pulse jet of 3 kg / m ² was used for the removal.
The results in the table are shown by the time required to reach the 80 mm water column after 50 times of the removal.

[0021]

Examples 1 to 5 Polyphenylene sulfide fiber (manufactured by Teijin Ltd., single yarn fineness 1.5 denier, number of fiber yarns 500 to 2000) 100% woven fabric (warp / weft density of 5 to 20 / inch) A web made of meta type aramid short fibers (Conex, Teijin Ltd., 2 denier x 51 mm) was laminated on both sides of the plain woven fabric (the web was made by a normal web warmer), and the punching density was 460 times / Normal needle punching was performed at cm ² to produce a filter cloth having a weight of 550 g / mm ² and a thickness of 20 mm. The evaluation results of the obtained filter cloth are shown in Table 1.

[0022]

Comparative Example 1 The spun yarn made of the meta-aramid short fibers used in Example 1 was used for both the warp and the weft, and the warp was 1
No. 0 twin yarn, hammering density 20 / inch, weft 20
Except for the count twin yarn and the shot density of 16 threads / inch,
Carrying out in the same manner as in Example 1, weight 500 g / m ² , thickness 2
A 0 mm filter cloth was prepared. The evaluation results of the obtained filter cloth are shown in Table 2.

[0023]

[Table 1]

[0024]

[Table 2]

Claims (1)

[Claims] 1. A filter cloth comprising a meta-aramid fiber felt, wherein a polyphenylene sulfide fiber is used as a base cloth for reinforcing the felt, which is a durability-improving filter cloth.