JPH10244110A - Bag filter laminated with cloth and polytetrafluoroethylene, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion between a cloth subjected to a water / oil repellent treatment and a porous polytetrafluoroethylene (PTFE) film, and to achieve both the acid resistance and the laminating property of the cloth. With the goal. SOLUTION: After subjecting a cloth to a water / oil repellent treatment, one side of the cloth is subjected to a flame treatment, and the treated cloth is laminated on a porous PTFE film, and a method for producing the bag filter. Bug filter obtained by.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bag filter used in a dust collector for filtering solid fine particles from an industrial gas stream.

[0002]

2. Description of the Related Art A bag filter collects dust by forming a cake layer of dust on the surface of a filter medium, and is widely used in industry. In recent years, in order to satisfy various characteristics required for bag filters such as high efficiency, heat resistance, chemical resistance, and low energy washability, porous polytetrafluoroethylene membranes (hereinafter “polytetrafluoroethylene” PTFE ”) is increasing.

[0003] When a porous PTFE membrane is used, it is common to laminate the porous PTFE membrane with another base material in order to obtain the strength required for removing dust and extend the life of the filter. It is. In addition, cloth is generally used as the other base material, and examples of the material of the cloth include glass fiber, graphitized fiber, polyamide fiber, polyester fiber, polyvinylidene chloride fiber, and fluorine fiber. Further, as a laminating method, the substrate melted by raising the temperature to a temperature higher than the melting point of the substrate is made of porous P.
Thermal lamination in which the TFE film is impregnated, lamination in which fibers or dispersion of a hot melt binder are sprayed on the interface, and the like are included.

[0004] Such a porous PTFE membrane has the best acid resistance among existing synthetic polymers, and can be used in a high-temperature gas in which an acid mist is expected to be present without impairing its performance. However, the acid resistance of a substrate is generally inferior to that of a porous PTFE membrane, and thus the acid resistance of a bag filter in which a porous PTFE film and a substrate are laminated is determined by the acid resistance of the substrate.

As a method for increasing the acid resistance of a substrate, there is a water / oil repellent treatment. Originally, the water / oil repellency treatment is a method used to enhance the water / oil repellency of the cloth. By coating the surface of the cloth with a fluorinated water / oil repellent, the surface free energy of the cloth is reduced, and the adhesion of water droplets and oil droplets is suppressed. By subjecting the bag filter base material to a water / oil repellent treatment, it is possible to prevent acid mist condensing from a gas stream from adhering and improve acid resistance. In addition, an improvement in acid resistance can be expected by coating the fiber surface of the cloth with a fluoropolymer having a carbon-fluorine bond having a large binding energy.

[0006]

However, when the water- and oil-repellent treatment is performed, the laminating property between the cloth and the porous PTFE film is deteriorated. Since the surface free energy of the adhesive surface of the cloth is reduced, the adhesion of the material that melts during lamination to the substrate is reduced, and sufficient lamination strength cannot be obtained.
When the laminate strength is reduced, there is a problem that the porous PTFE film and the base material are peeled off when the cake layer is removed, and the porous PTFE film is damaged.

[0007] The laminate of the present invention solves the above problems,
It is designed to achieve both acid resistance and laminating properties of the fabric.

[0008]

In order to solve the above-mentioned problems, a bag filter according to the present invention has a porous PTFE film laminated on one surface of a cloth subjected to a water-repellent and oil-repellent treatment with a scattered adhesive surface. Characterized by comprising a porous composite.

In the above bag filter, it is preferable that the scattered bonding surface is a bonding surface generated by flame-treating the cloth.

Further, the method of manufacturing a bag filter according to the present invention is characterized in that after performing a water / oil repellent treatment on the cloth, one side of the cloth is subjected to a flame treatment, and the treated cloth is laminated on a porous PTFE membrane. I do.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the bag filter of the present invention, a porous PTFE film is laminated on one surface of a cloth which has been subjected to a water / oil repellent treatment for imparting acid resistance, with a scattered adhesion surface. However, it is preferable that the scattered bonding surface is a bonding surface generated by flame-treating a cloth.

The flame treatment in the present invention refers to a treatment in which one surface of a cloth made of a heat-fusible material is instantaneously heated to a temperature equal to or higher than its melting point by a flame such as propane gas. By performing the flame treatment, the fibers on the cloth surface are partially melted, and the melted material contracts due to surface tension to form a large number of fine spherical pills. The surface of this pill loses its water / oil repellency effect.

When the flame-treated cloth and the porous PTFE film are laminated, the cloth and the porous PT
The FE film and the FE film are firmly laminated. In this case, since the water and oil repellency of the fiber surface of the cloth is preserved, the acid resistance of the cloth is not lost.

In order to achieve both laminating properties and acid resistance, it is desirable that the size of the pill is 0.2 to 0.6 mm in diameter and the distribution density of the pill is 3 to 10 / cm ² .

[0015] As the porous PTFE membrane, PTFE is used.
It is desirable to use a sheet obtained by a uniaxial stretching method or a biaxial stretching method in which the sheet is stretched in a direction perpendicular to the uniaxial direction. Normal thickness 5-200 μm, pore size 0.0
Those having a porosity of 1 to 50 μm and a porosity of 40 to 95% are used. The permeability of the membrane was 7 ml / at a pressure of 12.7 mmH ² O.
cm ² · sec (Fragile number 7) or more.

As the material of the cloth, a thermoplastic material is used for performing a flame treatment. Examples of the material of the cloth include polyamide fibers, polyester fibers, and polyvinylidene chloride fibers. The fabric may be a woven, knitted, non-woven, or the like. The thickness of the cloth used is desirably 0.1 to 2 mm.

The water / oil repellent treatment is performed to impart acid resistance, and is achieved by applying a water / oil repellent treating agent. As the water / oil repellent treatment agent, specifically, various fluorine-containing polymers are used. The polymer having a fluorinated side chain forms a film with low surface free energy on the surface of the fiber, and exhibits a water / oil repellent effect. Commercially available water- and oil-repellent treating agents include perfluoroalkyl polymers (trade names: Florard (manufactured by Sumitomo 3M), Texguard (manufactured by Daikin), Scotchguard (manufactured by Sumitomo 3M), Asahi Guard (Asahi Glass Co., Ltd.) Manufactured) can be used. As a method of applying the water / oil repellent treatment agent, impregnation, coating, spraying or the like can be used, but impregnation is preferred. The amount of the water / oil repellent agent is adjusted so that sufficient water / oil repellency is obtained and the air permeability of the cloth is not impaired within a significant range. Specifically, the application amount is 0.5 to 10
g / m ² is preferred.

When manufacturing the bag filter of the present invention,
Conditions for laminating the cloth and the porous PTFE film include a temperature of 290 to 340 ° C. and a pressure of 2 to 6 kg / c.
It is preferable to laminate at m ^{2 at} a speed of 1 to 5 m / min.

[0019]

Next, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

In the following Examples and Comparative Examples, a bag filter was prepared by heat laminating a porous PTFE membrane and a nonwoven fabric made of polyamide fiber. The porous PTFE membrane and the nonwoven fabric used were as follows. is there.

Porous PTFE membrane The porous PTFE membrane includes NTF1033 manufactured by Nitto Denko Corporation.
(A thickness of 15 μm and a pore size of 3.0 μ manufactured by a biaxial stretching method.
m, porosity 90%, and air permeability 20 ml / cm ² · sec).

Non-woven fabric The non-woven fabric is a Conex non-woven fabric FX408ZM manufactured by Nippon Felt Industry Co., Ltd. (thickness: 1.6 mm, basis weight: 475 g /
m ² , air permeability of 14 ml / cm ² · sec), and a water / oil repellent treatment was performed using a water / oil repellent treating agent Texguard TG-652 manufactured by Daikin. After impregnating the nonwoven fabric with a treating agent having a weight concentration of 6.5%, the nonwoven fabric was heated at 80 ° C. for 1 minute to form a film of the treating agent. The amount of the treatment agent attached is 10 g / m ^2.
Met.

Example 1 One side of a non-woven fabric was burnt with a propane gas flame to form hair balls having a diameter of about 0.5 mm / cm ² on average. The flame-treated surface of the nonwoven fabric and the porous PTFE film were thermally laminated. Lamination temperature 320 ° C, pressure 5kg / c
m ² , speed was 4 m / min, and air permeability after lamination was 3 ml / cm ² · sec.

Comparative Example 1 The nonwoven fabric and the porous PTFE film were laminated without performing the flame treatment. The laminating method is the same as in the first embodiment. The air permeability after lamination is 3 ml / cm ² · sec
Met.

The adhesiveness between the nonwoven fabric and the porous PTFE membrane of the laminates produced in Example 1 and Comparative Example 1 was evaluated. The results are shown in Table 1. In addition, this evaluation was performed as follows.

Evaluation Method of Adhesion High-pressure air was blown from the film surface of the laminate using an air gun (nozzle diameter: 2.0 mm). Spray angle is 3
0 °, the distance is 10 cm, and the time is 5 seconds. The presence or absence of peeling of the bonded surface between the nonwoven fabric and the porous PTFE membrane was examined.

[0027]

[Table 1]

From the results in Table 1, it was confirmed that the flame treatment improves the adhesion between the nonwoven fabric and the porous PTFE film.

[0029]

As described above, the bag filter according to the present invention, after laminating a cloth and a porous PTFE membrane, is subjected to a water / oil repellent treatment to impart acid resistance to the cloth, and then to the cloth. By laminating one side after the flame treatment, it is possible to improve the adhesion between the water- and oil-repellent cloth and the porous PTFE film.

[Brief description of the drawings]

FIG. 1 is a drawing showing a cross-sectional view of a representative laminate product of the present invention.

[Explanation of symbols]

 Reference Signs List 10 laminated product 11 porous PTFE membrane 12 pill 13 cloth (flame-treated product)

Claims (3)

[Claims] 1. A bag filter comprising a porous composite in which a porous polytetrafluoroethylene film is laminated on one surface of a cloth subjected to a water / oil repellent treatment by a scattered adhesive surface. 2. The bag filter according to claim 1, wherein the scattered adhesive surface is an adhesive surface formed by subjecting a cloth to a flame treatment. 3. A method for producing a bag filter, comprising: performing a water / oil repellent treatment on a cloth, performing a flame treatment on one side of the cloth, and laminating the treated cloth on a porous polytetrafluoroethylene film.