JPS588531A - Filter cloth - Google Patents

Abstract

PURPOSE:To obtain the filter cloth generating no swelling in a thickness direction during use, by pressing and setting a felt wholly comprising an aromatic polyamide type resin fiber as a dry filter cloth at a temp. of vitrification transition temp. or more. CONSTITUTION:A felt wholly comprising an aromatic resin type fiber such as a polymethaphenylene isophthalamide fiber is pressed and set at a temp. 270- 320 deg.C equal to or higher than glass transition temp. of said resin to form a dry filter cloth. Because this filter cloth is not swollen in a thikness direction during use, it is suitable for collecting a powder at a relatively high temp. and used in a lime factory or a clay factory.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to dry oven fabrics, particularly to dry oven fabrics suitable for use at relatively high temperatures of 160-1180°C.

Traditionally, glass fiber oven cloths have been used for high-temperature applications. Glass fiber furnace cloth is relatively inexpensive, but when used,
One drawback was that it was damaged due to bending and could not be made to withstand long-term use. To compensate for these drawbacks, furnace cloths made of wholly aromatic borioid fibers have come into use, and despite their relatively high price, they have become widely used in recent years because they can withstand long-term use. It's like K. However, the conventionally used dry P fabric made of fully aromatic boria (F-based fibers) begins to swell in the thickness direction after about one month of use, and due to the kernels, the F fabric O pores expand and become microscopic. The disadvantage of powder leakage was that it was not possible to achieve 1 m.For the sake of thickness, - increase the thickness of the fabric, or increase the number of threads of the base fabric by a certain percentage (and give up). We had no choice but to take such measures.

The present invention is based on the conventional dry method of fully aromatic porous fiber embroidery.
To provide a dry kiln cloth which does not undergo swelling in the thickness direction during use, which the cloth has.

Examples of the wholly aromatic polyamide resin used in the dry oven cloth of the present invention include polymethanephenylene inphthaland and polyvaraphenylene. Among them, Polymetha 7enji/Inphtaland is preferably used.

There is no limit to the thickness of the fibers used in the present invention, but preferably those with a thickness of L6 to large denier are used.
If necessary, a combination of fibers of two or more different thicknesses can be used as appropriate depending on the properties of the powder to be collected.

Further, the length of the fiber is not particularly limited, but preferably 38~
Fibers with a length of 102 mm, particularly preferably from 51 to 76 mm, are used.

The "felt" of the present invention made of such fibers refers to a so-called relatively thin woven material or a relatively thick felt material, and preferably needle-bunched material is used. These webs can be suitably made from raw cotton by conventional techniques such as card or sheet 7 ohm. Must see again!
Depending on the requirements, when wrapping the web, it is used to overlap the base fabric t-web.

The felt used in the present invention is preferably BOO~
Good for 600 f/&%, IL, <a400~500
A basis weight of f/- is adopted, and the apparent specific gravity is approximately αl to approximately α
1M is suitably used. 7/ The sealing of the needle punch which is a preferred embodiment [is 150
~300@/gd, preferably t! 1110~RIO Sashi/
- is used.

The dry F-fabric frame of the present invention is made of the felt prepared as described above and a wholly aromatic boria-based resin glass (15).

It is obtained by pressurizing and setting at a temperature higher than the transition point, preferably higher than the glass transition point, and up to a temperature exceeding the glass transition point t-sO°C. In the case of polymetaphenylene inphthalamide resin, which is a preferred dormitory axis of the present invention, VCFi
Pressure is set at a temperature of 27°C to 820°C, preferably above the glass transition point of 260 to 270°C. As used herein, "pressure setting" refers to an operation of processing felt so as to maintain a predetermined and stable thickness by applying pressure under heating conditions.

The pressure setting method is not particularly limited as long as it presses the felt at a temperature higher than the glass transition point for a certain period of time, but a flat plate press method and a heated roll method are preferable, and a flat plate press method is particularly preferable. will be adopted. In the flat plate pressing method, raw material felt is placed between flat plates preheated to a predetermined temperature above the glass transition point of fully aromatic polyamide resin, and is pressurized for a long period of time to prevent swelling and aeration over a long period of time. A dry kiln cloth with a stable finish can be obtained.

The press temperature fjt should be equal to or higher than the glass transition point of the resin, preferably 270-3! Preferably 2〒6 to 0℃%
~300°C is adopted. If it is less than s'to'c, the non-swelling properties of the obtained furnace cloth will be insufficient, and if it exceeds ato'ct, the Fi furnace cloth will harden into a paper-like shape and become brittle, which is undesirable. Although not particularly limited, it is preferable to adopt Fizo-too seconds of 4?, preferably 40 to 70 seconds; less than 20 seconds is not preferable because the obtained furnace cloth will have insufficient non-swelling properties; Beyond Fip
This is not preferable because the cloth hardens into a paper-like state.

The heating roll method is carried out by placing the felt on a heating roll having a heating medium or electric heating means as appropriate, and the heating source f is applied to the surface of the roll. −・〜B$O℃ is good jl
, (,8m)0℃～B! 11: is particularly preferred, 29
Below 0°C, - the non-swelling properties of the fabric are insufficient;
On the other hand, if the ct is too high, the furnace cloth will harden into a paper-like state, which is undesirable, but an embodiment in which the heating hole method or the raw felt is preheated is preferably adopted. Preheat with an appropriate heater! It is carried out at 70-ago°C, preferably 280-SOO°C. By performing preheating, the speed of rolling can be significantly increased, improving productivity.

The compression ratio in the flat plate press method and heated roll method (the ratio of the thickness of the product to the fabric to the thickness of the raw material felt) is preferably 1O2 to 10:3, and particularly preferably 1026 to 10:4. . . Press pressure and roll pressure are appropriately selected so as to obtain a predetermined compression ratio.

The dry fabric of the present invention thus obtained generally has an apparent density of a! 5 to aao1, thickness l-2-1
Air permeability is I m-100C/CIIIL'/a a
a (where Δp=12.Qi water column). However, the appearance, density, thickness, and air permeability can be changed as necessary, and the present invention is not limited to this scope.

Thus, the dry furnace cloth obtained according to the present invention hardly swells even when used at a relatively high temperature of 1180 to 2 sO ℃ and for a long period of time, compared to the furnace cloth according to the prior art. It has an excellent property of maintaining stable ventilation f. The disadvantage of conventional products is that the thickness increases and swells after a month of use, and as a result, the air permeability increases over time, making collection of relatively fine particles incomplete or impossible. The dry-fabric of the present invention overcomes this problem.

The dry oven cloth of the present invention has a special Kl@0~! ! 3G'CO is suitable for collecting powder at relatively high temperatures, such as lime factories, etc.
For collecting dust or powder products at china clay factories, chemical factories, cement factories, etc., and for collecting fine powder in waste gas from Kiepora, electric furnaces, heavy oil boilers, coal boilers, wood powder boilers, metal melting furnaces, asphalt plants, etc. Preferably used.

Example 1 Polymetaphenylene isophthalide resin fiber (borrowed,
Woven fabric made of cornex@) (number of threads vertically 24 x
ii 22/Z, 5 all, electric 100f/r
r? ) was attached with a web made of the fibers (denier x 76 m5) obtained using a normal web former, and a raw material felt (weight 4 sots/-1 thickness (size 8■) was set under pressure using a flat plate press under the following conditions.(Compression ratio 1G
:&? ) Experiment number Temperature Pressure Time
Spacer gauge l (conventional product) 150-160'Ctsi9/j so
Second lSm2 24G-250℃1.5Kp/m
60 seconds 155w+3280~290℃LrhKe/c
d 60#L'm4310~32Q'CL, S scent/c
d6G? First, the non-swellability of the obtained felt cloth was tested using the following swelling acceleration test method. The comparative evaluation results are shown in the table below, and the evaluation is based on the thickness before and after the swelling acceleration test
It depends on the increase rate of a) and the texture of the furnace cloth.

Swelling acceleration test method: The sample is soaked in boiling water for 5 hours.

Then in the oven at 200℃! ! After exposing the sample to hot air for 4 hours, a bag was made from the sample of test number 1 (conventional product) and the sample of experiment number 3, and it was attached to a dust collector (Micropulse Air) for Cubola exhaust gas. The non-swelling properties of Ru-fabric were comparatively evaluated in mixed operation. The results are shown in the table below.

Operating conditions Exhaust gas - strange 100'cX! 4-hour operation exhaust gas dust-containing device 6f/Ngl exhaust gas dust-containing pipe 300i/111 (co-filtration area
! 4-0- Filtration rate 1 [L! Shukaku/S (@ The drawing shows an enlarged schematic diagram of the cross section of the furnace fabric sample tested.

Figure 1 shows the samples of experiment number l and experiment number snow before the test, Figure 2 shows the samples of experiment number 3 after 6 months of use, and Figure 3 shows the samples of experiment number l after 6 months of use. It is an enlarged schematic diagram of a cross section. T, I is L @ m,? ', is 'L8-1? '
, Filjl ■.

Woven fabric made of cornex@n (number of threads vertically! 4 x
w=r11 pieces/L 6 as'), weight 1 ($02/
y/'s rMK normal questup foo! A 9-raw material felt (weight @ 4B
0f/d, thickness 3LOw, ) T-flat plate press was set under pressure under the following conditions. (Compression ratio 1:&3) Temperature Pressure Time Great! - Gauge mso℃
Limp/j 6o seconds LgwNon-liquidity tube was evaluated by the swelling acceleration test described in Example IK.

Thickness increase rate Ventilation increase rate Hearth cloth texture Overall evaluation t
ts* as-good 0 Example 3 1I! II/IAf! The raw material felt obtained in step 41 was pressurized and set in a heating roll (11 m + - x 2 rolls) for 1 - next OS condition. (Compression ratio l・:&S) Temperature Pressure Roll speed Clearance me・
-110'c 8Ky/ml lL4M/s (s
LlmThe non-swelling properties of the obtained felt-cloth are shown in Example 1.
011! Evaluations similar to those of the sample in the experimental series were obtained.

The raw material felt obtained in Example *N1 was set under pressure using a heating roll equipped with a preheated opening under the following conditions. (Compression ratio 10:&8) Preheat open Clear temperature Roll temperature Roll * rl 9
280-2110℃800-110℃ a6M
The non-swellability of the obtained furnace cloth was evaluated as the same as that of the sample of Experiment No. 3 in the Examples.

[Brief explanation of the drawing]

FIGS. 1 to 3 are enlarged schematic cross-sectional views of the furnace cloth, where l indicates a felt layer and 2 indicates an attached dust layer.

Claims (1)

[Scope of Claims] l) Dry F cloth made by pressing felt made of wholly aromatic boriad resin fibers at a temperature higher than the glass transition point of the resin; 2) The felt is needle punch felt. A dry F fabric according to claim 1. 3) The P fabric for dry process according to claim 113 or *g*, wherein the wholly aromatic polyamide is a volume 7 aerene isophthalate. Reef) Claim 1, which is a dry type fabric for a slag collecting machine
The dry-processed cloth according to any one of Items 1 to 3.