JP2002348765A - Fabric and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a fabric having excellent collecting properties of fine dusts and excellent abrasion resistance without deteriorating characteristics of fluororesin fibers and a method for producing the fabric. SOLUTION: In this fabric, fibrillated fluororesin fibers produced by an emulsion spinning method are present on the surface of the fabric, unfibrillated heat-resistant fibers are present in the interior of the fabric and the minimum fineness of the fibrillated fluororesin fibers is <=0.1 dtex. The method for producing the fabric is characterized by applying physical shocks to the surface of the fabric composed of only the unfibrillated fluororesin fibers and producing the fibrillated fluororesin fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cloth used as a material for a filter or a material for sealing fine particles.
The present invention relates to a fabric having a high dust collection efficiency of μm or less and having excellent abrasion resistance, and also relates to a method for producing the fabric.

[0002]

2. Description of the Related Art Fluororesin-based fibers are known for their excellent heat resistance, chemical resistance, electrical properties, and low friction coefficient.
Widely used for industrial materials. Above all, it is widely used for bag filters in garbage incinerators, and composites of fluororesin fibers and glass fibers are widely used. Alternatively, a bag filter using a heat-resistant fiber other than glass fiber, for example, aramid, polyphenylene sulfide, polyimide, or polyparaphenylene benzoxazole is widely used.

With respect to the bag filter using the above-mentioned heat-resistant fiber, a bag filter having higher dust collection efficiency is required at present. This is, for example, a bag filter used in a gasification melting processing furnace or the like, and is a filter having a high collection efficiency capable of collecting dust having a small particle diameter.

[0004] Alternatively, a fine particle sealing material using a fluororesin fiber is widely used. For example, it is a toner sealing material for a printer, and seals minute toner at a temperature of 150 ° C. or higher. As the colorization of toner progresses, there is a demand for a material that can seal finer toner.

Therefore, a method has been proposed in which a microporous film of a fluororesin is adhered to the felt surface of the heat-resistant fiber and dust is collected with high efficiency by the microporous film (Japanese Patent Laid-Open No. 2000-2000).
-140588, etc.). In this method, 0.5
Although the efficiency of collecting dust having a particle size of μm or less is high, there is a problem that the fine porous film made of fluororesin is peeled off due to poor adhesion between the material and other materials. Further, when used for a bag filter, friction occurs with the retainer when a backwash pulse is applied, and therefore, there is a problem that peeling occurs due to the frictional force.

[0006] Alternatively, Japanese Patent Application Laid-Open No. 4-032649
As described in the publication, the ultrafine fiber layer and the felt base material layer are integrated by needle punching, and the distribution of ultrafine fibers is gradually reduced from the front to the back, and then can be ultrafine by a high-pressure water punch. A filter having a high collection efficiency that divides and ultrafine fibers is known. However, in this method, it is necessary to laminate two or more different fibers, and there is a problem that there are many processing steps. Further, the ultra-fine-thinning fibers of this patent are merely exemplified as polyamide / polyester split fibers.

[0007] Japanese Patent Application Laid-Open No. 2000-61224 describes a filter medium using a fluororesin fiber having branches and / or loops. A fiber that is branched and / or looped by needle punching. The fabric having branches and / or loops obtained by this method has a problem in that the strength of the web is reduced because the fluororesin fibers are divided over the surface, inside, and the entirety.

[0008]

DISCLOSURE OF THE INVENTION In view of the background of the prior art, the present invention has improved fine dust collection and excellent abrasion resistance without impairing the characteristics of fluororesin fibers. It is intended to provide a fabric and a method for producing the same.

[0009]

The present invention employs the following means in order to solve the above problems. That is, the fabric of the present invention has fibrillated fluororesin-based fibers produced by an emulsion spinning method on the surface of the fabric, and heat-resistant fibers that are not fibrillated inside the fabric, and the fibrillated fibers. The minimum fineness of the obtained fluororesin-based fiber is 0.1 dtex or less. Further, the method for producing such a fabric includes applying a physical impact to the surface of the fabric composed of only the non-fibrillated fluororesin-based fibers to generate fibrillated fluororesin-based fibers on the surface. It is a feature.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been made to thoroughly study the above-mentioned problem, that is, a fabric excellent in collecting fine dust without deteriorating the characteristics of the fluororesin fiber, and forming a fibril on the surface of the fabric. By arranging the above-mentioned fluororesin-based fibers and arranging non-fibrillated heat-resistant fibers inside the fabric, the present inventors have sought to solve such a problem at once.

It is important that the fibrillated fluororesin fibers produced by the matrix spinning method of the present invention have a minimum fineness of 0.1 dtex or less. Fineness is 0.1d
tex or less fibril yarn,
This is for exhibiting an excellent function of collecting dust of 0.5 μm or less.

The emulsion spinning method referred to herein is a wet emulsion spinning method (emulsion spinning method) in which a matrix polymer and a fluororesin polymer are mixed to form an emulsion, and the emulsion is discharged from a molding die into a coagulation bath to form fibers. Or matrix spinning method).

The heat-resistant fiber mentioned here is preferably a fluororesin-based fiber. Because heat-resistant fibers such as aramid, polyphenylene sulfide, polyimide, polyparaphenylene benzoxazole or glass fiber are well known, each of these materials has superiority and inferiority. This is because they exhibit excellent performance in a well-balanced manner. For example, aramid has an excellent decomposition temperature of 500 ° C. or higher, but has a weak point of low acid resistance. Polyphenylene sulfide has excellent chemical resistance, but has a melting point of 285 ° C.
And heat resistance is slightly low. Polyimide has some problem in alkali resistance, and polyphenylene benzoxazole has high strength, but its market price is very high.
Although the glass fiber has a decomposition point of 700 ° C. or higher, there is no problem with heat resistance, but there is a problem with alkali resistance. On the other hand, fluororesin fibers, especially polytetrafluoroethylene (hereinafter PTFE), are very excellent except that they are soluble in a specific perfluorinated organic liquid at 299 ° C. or higher and are slightly attacked by molten alkali metal. Since it shows chemical resistance and has a high heat resistance of a high temperature of 327 ° C., it is suitable for filter applications.

As such a fluororesin fiber, PTF is used.
E is most preferred, but tetrafluoroethylene-6-fluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkoxy group copolymer (PFA) or tetrafluoroethylene-olefin copolymer (ETFE) Etc. can also be used.

In the fabric of the present invention, the fibrillated fluororesin fibers preferably occupy 50% or more of the total area of the fabric surface. If less than 50% of the total area is occupied, only a cloth having a low dust collection efficiency of 0.5 μm or less can be obtained.

[0016] In the fabric of the present invention, the minimum fineness of the surface is 0.1.
It is preferable to use a fabric in which there is a fibrillated fluororesin fiber having a dtex of 1 dtex or less, and the proportion of the fluororesin fiber having a large fineness gradually increases from the surface toward the inside. This is because a fabric made of a fluororesin fiber fibrillated entirely in the thickness direction of the fabric is not preferable because the constituent fibers are all finely divided and the strength of the fabric is reduced.

Further, JIS L 1096 of the fabric of the present invention is used.
Is preferably 10 cc / cm ² / sec or less. Because when used for bag filter applications, 10
In the case of a fabric having an air permeability exceeding cc / cm ² / sec, the effects of gravity settling and Brownian diffusion in the filtering mechanism of the filter are reduced, and as a result, the collection efficiency is undesirably reduced.

The collection efficiency referred to here is such that the particle diameter is 0.5 μm.
It is measured using a particle counter at a wind speed of 1 m / min with dust of m or less. Those having a collection efficiency of 60% or more are preferred as the fabric of the present invention. This is because a filter having a trapping efficiency of less than 60% has a low filtration function inherent in the filter, and therefore, the filtration of fly ash generated from a gasification melting processing furnace or the like is insufficient. At the same time, in the case of a fabric having a collection efficiency of less than 60%,
It is not preferable because it does not exert a sufficient effect on sealing the color toner. Further, a fabric having a collection efficiency of 80% or more, more preferably 90% or more under the same conditions is suitably used for a filter for collecting fine dust.

According to the fabric of the present invention, not only a filter for collecting fly ash and dust but also a filter for liquid can be used without any problem.
Such a material for a filter or a material for sealing fine particles can be provided. In addition to the filter material mentioned here, it can be used as a fine particle sealing material, for example, a toner sealing material for a printer, but is not limited to these applications.

Next, a method for manufacturing such a fabric will be described. That is, a cloth made of such a fibrillated fluororesin fiber is subjected to a physical impact on the surface of a cloth composed of only a non-fibrillated fluororesin fiber, whereby a fibrillated fluororesin fiber is formed on the surface. It is manufactured using means for producing fibers.

The cloth made of non-fibrillated fluororesin fibers can be used without any problem as long as it is a felt in which a web made of short fluororesin fibers is integrated with a needle punch. Further, in the felt referred to here, a web made of short fibers of a fluororesin fiber and a base fabric made of a woven fabric composed of multi-filaments or monofilaments of heat-resistant fibers may be laminated, or alternatively, from a fluororesin fiber. A simple woven or knitted fabric can be used without any problem.
Furthermore, the fabric made of the non-fibrillated fluororesin-based fiber may be a single web made of the fluororesin-based fiber, or a fabric obtained by calendering the web or a resin-bonded nonwoven fabric cured by attaching a resin. It can be used without.

The physical impact of the present invention is preferably a high pressure jet water treatment. This is because, by performing the high-pressure jet water flow treatment, a physical impact can be given while minimizing the occurrence of a needle hole generated by a needle punch or the like and a rupture of a fiber.

The high-pressure jet water flow treatment here is 5MP.
a. The above processing pressure is preferable. When the processing pressure is 5 MPa. If it is less than 50%, the fibers do not fibrillate, and only a cloth having a low dust collection efficiency of 0.5 μm or less can be obtained.

[0024]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

The method for measuring the physical properties of the fabric is as follows. [Ratio of fibril yarn to total area of fabric surface (hereinafter referred to as fibril ratio)] Take a photograph of the surface of the fabric,
The area occupied by fibril yarn was read. Shooting magnification is 5
At 0x, a video high scope was used. [Air permeability] It was measured based on the Frazier method specified in JIS L 1096. Five measurement samples were randomly selected and measured. [Minimum fiber diameter] A cross-sectional photograph of the fabric is taken with an electron microscope,
The fiber with the smallest fiber diameter is selected, and the fiber diameter of the fiber is read. The photographing magnification is 1000 times. [Wear strength] It was measured by the universal method described in JIS L 1096. Sandpaper of # 320 was used as the polishing paper. [Collection efficiency] The collection efficiency was measured by the air dust counting method.
This is data obtained by measuring the dust collection efficiency in the atmosphere using a particle counter with a dust particle size of 0.5 μm or less and a filtration wind speed of 1.0 m / min.

(Example 1) PTFE staple fiber (TOYOFLON 7.4 manufactured by Toray Fine Chemicals)
(dtex x 70 mm) to obtain a web. Thereafter, a woven fabric made of PTFE multifilament (TOYOFLON # manufactured by Toray Fine Chemicals Co., Ltd.)
4300), the above web is laminated on both sides,
Needle punching treatment was performed at 50 needles / cm ² to integrate them, and a felt 1 was obtained. The treatment water pressure was 15 MPa. 3 times from the front and back sides of the felt 1. Then, a water jet punch treatment was performed at a feed speed of 5 m / min to obtain a fabric 1 having a fibrillated surface. (Example 2) From the front and back surfaces of a woven fabric (# 1801 manufactured by Toray Fine Chemical Co., Ltd.) composed of PTFE multifilament, the treatment water pressure was 15 MPa. , Feed speed 3m / m
In, a water jet punch treatment was performed to obtain a fabric 2 having a fibrillated surface.

(Comparative Example 1) The felt 1 obtained in Example 1 was treated with a treatment water pressure of 4.5 MPa. ,
Water jet punch treatment was performed at a feed speed of 5 m / min to obtain a fabric 3 having a non-fibrillated surface.

Comparative Example 2 Staple fiber of polyethylene terephthalate (Tetron T205- manufactured by Toray)
(7.7 T x 64 mm) is carded to obtain a web. Needle punching was performed on the web at a rate of 350 needles / cm ² to integrate the web into a felt 2. After that, treatment water pressure 15MP 3 times from the front and back of felt 2
a. Water jet punching was performed at a feed speed of 5 m / min to obtain a fabric 4 having a non-fibrillated surface.

(Comparative Example 3) After the fluorine-based dispersion adhesive was sprayed on the felt 1 obtained in Example 1, P
A TFE membrane (Microtex manufactured by Nitto Denko Corporation) was laminated and dried, and the nonwoven fabric and the PTFE membrane were integrated to obtain Fabric 5.

[0030]

[Table 1]

As is clear from the test results in Table 1, the fabric of Comparative Example 1 has a large fiber diameter and a collection efficiency of less than 60%, which is lower than the collection efficiency of the fabric of the example. The fabric of Comparative Example 2 also has a low collection efficiency. Further, the cloth of Comparative Example 3 has a high collection efficiency because a microporous PTFE film is adhered thereto. However, when the abrasion strength was measured by a universal method, the PTFE film on the surface was peeled off after 50 times of abrasion. And the reduction of the collection efficiency is remarkable, which is inferior to the examples.

[0032]

According to the present invention, it is possible to provide a cloth which is excellent in collecting fine dust of 0.5 μm or less and which is excellent in abrasion resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D06B 19/00 D06B 19/00 Z D06M 17/00 D06M 17/00 J F-term (Reference) 3B154 AA09 AB21 AB22 BA25 BA51 BB02 BB33 BC08 BE04 BF02 BF06 BF07 BF14 BF30 DA30 4D019 AA01 BA13 BB02 BB03 BB10 BC12 BD01 BD02 BD04 BD10 CB06 DA01 DA03 DA08 4L032 AA04 AB02 AC01 BD05 CA00 DA00 EA00 EA06 4A04 A04 AB04 A04 AB04 A04 AB04 A04 AB04 A04 4A04 AB07 CA00 CA09 CA11 CA15 DA40 EB00 EB03

Claims (9)

[Claims] 1. A fibril-containing fluororesin-based fiber produced by an emulsion spinning method on the surface of a cloth, a non-fibrillated heat-resistant fiber inside the cloth, and the fibrillated fluororesin. A fabric, wherein the minimum fineness of the system fiber is 0.1 dtex or less. 2. The fibrillated fluororesin fiber comprises:
2. The fabric according to claim 1, wherein the fabric occupies 50% or more of the total area of the fabric surface. 3. A minimum fineness of 0.1 dte on the surface of the fabric.
2. The ratio of the fluororesin fiber having a fineness gradually increasing from the surface toward the inside of the fibrilized fluororesin fiber which is equal to or less than x.
Or the fabric according to 2. 4. The air permeability of the cloth measured according to the Frazier method defined in JIS L 1096 is 10c.
fabric according to any one of claims 1 to 3, characterized in that c / cm ² / sec or less. 5. The cloth according to claim 1, wherein the collection efficiency of dust having a particle diameter of 0.5 μm or less is 60% or more at a wind speed of 1 m / min. Cloth. 6. The fabric according to claim 1, wherein the fabric is a filter material or a fine particle sealing material. 7. A fabric characterized in that a physical impact is applied to the surface of a fabric composed solely of non-fibrillated fluororesin fibers to produce fibrillated fluororesin fibers on the surface. Manufacturing method. 8. The method for producing a fabric according to claim 7, wherein said physical impact is a high-pressure jet water flow treatment. 9. The processing pressure of the high-pressure jet water flow treatment is 5MP.
a. 9. The method for producing a fabric according to claim 8, wherein: