JP2554259Y2 - Filter cloth - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter cloth for a bag filter suitable for capturing and collecting fine dust in a fluid.

[0002]

2. Description of the Related Art Filter cloth used for collecting fine dust in a gas, such as a bag filter, is required to be dense in addition to high strength and form stability. And heavy woven and non-woven fabrics are used. However, in recent years, more accurate dust collection has been required in various fields, and it is difficult to meet these requirements with conventional filter cloths. I have. In response to this demand, for example, as disclosed in Japanese Patent Application Laid-Open No. 3-60712, there has been proposed a filter cloth in which a nonwoven fabric sheet made of ultrafine fibers having an average fineness of 0.2 denier or less is laminated on the surface of a needle felt.

[0003]

However, a filter cloth obtained by laminating a nonwoven fabric sheet made of ultrafine fibers having an average fineness of 0.2 denier or less on the surface of a needle felt is excellent in strength, form stability and fine particle collection. Although it has many advantages of good dust efficiency, the filtration surface (dust supply side) is only smoothed by pressing during lamination, and it is not always satisfactory in removing dust attached to the filtration surface Not something to do. And the pay-off of the good or bad will be及boss an effect on the exchange period of pressure loss and filtration cloth. The present invention has been made to improve the above problems.

[0004]

SUMMARY OF THE INVENTION The present invention uses a low-melting ultrafine fiber and a high-melting ultrafine fiber for at least a part of a non-woven fabric to be bonded onto a woven fabric base, and smoothes the filtration surface with a hot roll. In some cases, the low-melting ultrafine fibers were softened to suppress the air permeability, further increase the smoothness of the filtration surface, and improve the dust removal property. That is, the present invention has, on basis weight of the fabric the base fabric of 200 to 800 g / m ^2, the splittable conjugate fibers
There the low melting point microfine fiber thickness 0.5 denier or less that are formed by dividing a high melting point microfine fibers is 1: The mixed ultrafine fiber material in a ratio of 1 contains at least 50% by weight or more, and
Needle punch or high
A nonwoven fabric having a basis weight of 60 to 250 g / m ² entangled by a pressurized liquid flow is joined via a binder, and the surface of the nonwoven fabric is subjected to a heat calendering treatment to soften the low-melting point ultrafine fibers on the filtration surface and to reduce the distance between adjacent fibers. The filter surface is smoothed by bonding, and the air permeability is suppressed to 3 to 15 ml / cm ² / sec to form a filter cloth.

[0005] The low melting point ultrafine fiber and the high melting point ultrafine fiber are:
The ultrafine fiber material of 0.5 denier or less mixed at a ratio of 1 can be obtained by dividing the splittable conjugate fiber. As constituent components of the splittable conjugate fiber, for example, polyethylene, polypropylene, poly-4-methylpentene-1, ethylene-vinyl alcohol copolymer, polyolefin-based polymer or copolymer such as ethylene-vinyl acetate copolymer, Polyester polymers or copolymers such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 66, nylon 1
Although it can be appropriately selected from polyamide-based polymers or copolymers such as No. 2 and the like, it may be composed of two or more components having a melting point difference of 20 ° C. or more. Various fiber cross-sectional shapes of the splittable conjugate fiber can be considered and are not particularly limited, but a radial type is preferable.

[0006] The nonwoven fabric layer serving as a filtration surface contains at least 50% by weight, preferably at least 85% by weight, of ultrafine fibers of 0.5 denier or less obtained by dividing the splittable conjugate fiber.
Nonwoven to 250 g / m ² is preferred. For the non-woven fabric, the above fibers are formed by a card method, a cross-layer method, a random webber method,
Nonwoven fabrics are formed by wet papermaking, dry or wet heat bonding, needle punching, high-pressure liquid flow, etc. High pressure liquid flow treatment is particularly preferable, and the discharge water pressure is 30 to 200 kg.
/ cm ² , preferably 80-150 kg / cm ² , speed 1-5 m /
It is preferable to perform the treatment at least twice on each of the front and back sides with min.
If the discharge water pressure is less than 30 kg / cm ² and the speed is higher than 5 m / min, the division will be insufficient, the efficiency of collecting fine particles will not be improved, and if the discharge water pressure is higher than 200 kg / cm ² and the speed is less than 1 m / min, excessive processing will be performed. It is uneconomical. In addition, 5
Other fibers of less than 0% by weight can be mixed, but other fibers may be selected from natural fibers such as cotton and hemp, semi-synthetic fibers such as rayon, and synthetic fibers such as polyolefin, polyester and polyamide according to the intended use. May be selected as appropriate.
If the ultrafine fibers exceed 0.5 denier, if the content of the ultrafine fibers is less than 50% by weight, and if the basis weight is less than 60 g / m ² , fine particle capture cannot be expected. Conversely, even if the basis weight of the nonwoven fabric is 250 g / m ² or more, the efficiency of capturing fine particles does not increase so much and only the cost increases.

The woven fabric base fabric may be any fabric that is made of fibers having a melting point higher than that of the low melting point component of the nonwoven fabric layer. For example, it is composed of synthetic fiber spun yarn of 1.5 denier or more, multifilament, and filter cloth. A woven fabric that can maintain strength and form is preferred. As the synthetic fibers used in the woven fabric, any of single component fibers or side-by-side, core-sheath, split, and sea-island composite fibers can be used.
From the viewpoint of economy, a monocomponent fiber is preferable. For example, the above-mentioned fibers such as polyolefin, polyester, and polyamide may be used. The basis weight of the woven fabric is 200 to 80
0 g / m ² , preferably 400 to 600 g / m ² , if the basis weight is less than 200 g / m ^2, it is difficult to maintain the form as a filter cloth, and if it is more than 800 g / m ² , the filter cloth becomes bulky. Become.

[0008] The filter cloth of the present invention is integrally formed by hot calendering with a hot melt agent interposed between the nonwoven fabric obtained above and the woven fabric base cloth. At the time of this heat calendering, the low-melting ultrafine fibers on the surface of the nonwoven fabric layer are softened or partially melted and joined to the adjacent fibers, and the degree of softening or melting is adjusted so that the air permeability is 3 to 15 ml.
/ cm ² / sec, preferably 5 to 10 ml / cm ² / sec. If the softening and melting of the low-melting ultrafine fibers become excessive, the resinification of the surface becomes remarkable, the air permeability becomes less than 3 ml / cm ² / sec, and the dust wiping property is improved. A load is applied and the filter cloth needs to be replaced in a short period of time. In addition, if the softening of the low melting point ultrafine fibers on the surface of the non-woven fabric layer is insufficient, the fibers cannot be bonded to each other, the air permeability exceeds 15 ml / cm ² / sec, and the pressure loss during use is small, but the surface smoothness is low. Insufficiently, the ability to remove dust adhering to the surface of the nonwoven fabric is deteriorated, and the dust collection efficiency is reduced.

As a hot-melt agent for joining the nonwoven fabric layer and the woven fabric, generally used low melting point materials such as polyamide, polyester, and polyolefin may be used. And the like are preferred.

[0010] The conditions of the heat calendering process for joining the nonwoven fabric layer and the woven fabric base are as follows: a hot roll and a normal temperature roll having a range from the softening point of the low melting point ultrafine fiber of the nonwoven fabric layer to the melting point of the high melting point component. Using a calender roll with a non-woven fabric layer side as a heat roll, a linear pressure of 50 to 100 kg / cm, and a speed of 3
処理 7m / min. Linear pressure 100kg / c
If the speed is not less than 3 m / min and less than 3 m / min, the low-melting ultrafine fibers are excessively softened and melted, and the air permeability is reduced. On the other hand, if the linear pressure is lower than 50 kg / cm and the processing speed is higher than 7 m / min, the softening of the low melting point ultrafine fibers on the surface of the non-woven fabric layer becomes insufficient, so that the fibers cannot be bonded to each other, and the dust can be easily removed. Cannot make surface .

[0011]

The filter cloth of the present invention is a non-woven fabric containing ultra-fine fibers of 0.5 denier or less, which maintains the strength and dimensional stability with a woven fabric base and forms a filtration surface (dust supply side surface). The layer collects fine dust. The smooth surface formed by the fiber bonding due to the softening of the low-melting ultrafine fibers suppresses fluff, improves the dust collection efficiency of the fine particles, and improves the dust removing property.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings showing an embodiment of the present invention, FIG. 1 shows (1) a filter cloth, (2) a nonwoven fabric layer, and (3) a fabric base cloth. I have. As shown in FIG. 2, the nonwoven fabric layer (2) has nylon 6 (melting point 214 ° C.)
A splittable conjugate fiber (16-split type) obtained by alternately arranging polyethylene terephthalate (melting point: 256 ° C.) as a component B (5) to be a high melting point ultrafine fiber at a spinning temperature of 29
Spun at 0 ° C for melt composite extrusion, stretched 3 times in hot water at 75 ° C, cut and cut to 3 denier, 45 mm splittable composite fiber
The staple of (6) is used, and this splittable conjugate fiber (6) is
After making a card web with a card machine by using a 100% by weight, a high-pressure liquid flow treatment was performed three times on each of the front and back sides at a water pressure of 150 kg / cm ² and a speed of 3 m / min to reduce the splittable conjugate fiber (6) to a low A component (4) A non-woven fabric having a basis weight of 120 g / m ² , which was divided into ultra-melting point ultrafine fibers (0.19 denier in thickness) and high-melting point ultra-fine fibers of component B (5) (0.19 denier in thickness) and entangled between the fibers, was used.

As the woven fabric fabric (3), a plain woven fabric having a basis weight of 400 g / m ² woven by using twisted yarns obtained by twisting three polyester spun yarns having a cotton count of 5 ^S as warps and wefts was used. .

A low-melting polyester-based hot melt agent (7) having a basis weight of 25 g / m ² is interposed between the nonwoven fabric layer (2) and the woven fabric base fabric (3). Using a heat roller at ℃ and a calender roller with the fabric base fabric (3) side as a normal temperature roller, calendering is performed at a linear pressure of 100 kg / cm and a speed of 4 m / min to obtain a low melting point on the surface side of the nonwoven fabric layer (2). The ultrafine fibers are softened to bond the adjacent fibers (8), and the hot melt agent (7) is melted to integrate the nonwoven fabric layer (2) and the fabric base fabric (3) to form a filter cloth (1). Done This filter cloth
The air permeability of (1) was 6.2 ml / cm ² / sec.

[Comparative Example 1] A filter cloth was formed in the same manner as in the example using the same woven fabric as the example and the basis weight of the nonwoven fabric layer in the example was 50 g / m ² . The air permeability of this filter cloth was 9.6 ml / cm ² / sec.

Comparative Example 2 A nonwoven fabric having a basis weight of 120 g / m ² was used as a nonwoven fabric layer, and a low-melting hot-melt agent was interposed on the same woven fabric as in the example. The filter cloth was adhered to form a filter cloth without softening or melting of the ultrafine fibers on the surface. The air permeability of this filter cloth is 18
ml / cm ² / sec.

Table 1 shows the results of evaluating the filtration performance of the filter cloths of the examples and comparative examples 1 and 2.

The filtration performance was evaluated as follows. Using 10 kinds of JIS test dusts, a test was conducted with a pulse type dust tester. The conditions of the tester were set as follows. Air volume 2.5m ³ / min, filtration area 0.66m ² , pulse interval 2min, 0.1sec / 1 pulse, pulse pressure 3kg / cm ² , test time 7hr, temperature (room temperature), primary adhesion layer for acceleration The formation was performed without dusting off until the pressure on the filter cloth reached ΔP = 150 mmH ₂ O.

Dust leakage amount (g): Weight collected by filter paper capable of collecting up to 0.1 μm of dust that has passed through the filter cloth. Dust collection efficiency (%): Inlet dust concentration A from dust feeder
(G / m ³ ), and the outlet dust concentration B (g / m ³ ) was measured based on the amount of air passing through the filter cloth and the amount of dust leakage, and the dust collection efficiency (%) = [1- (B / A) )] × 100. Permeability decrease (%): Permeability C (ml / cm ² / se) before the above test
c) and the air permeability D (ml / cm ² / sec) after the test were measured, and calculated from the equation of air permeability reduction (%) = [1- (D / C)] × 100. Pressure loss (mmH ₂ O): the test ΔP = 150mmH ₂ maximum value after O. Dust removing property [Dust adhesion amount (g / m ² )]: Dust weight obtained by measuring the weight of the filter cloth after the above test and subtracting the weight of the filter cloth before the test. (The smaller the dust weight, the better the peelability.)

[0020]

[Table 1]

[0021]

[Effect of the Invention] The filter cloth (1) of the present invention has a basis weight of 200 to
On the 800 g / m ² woven fabric base (3), the splittable conjugate fibers are separated.
Split by a low melting point microfine fiber thickness below 0.5 denier formed by the high melting point microfine fibers is 1: The mixed ultrafine fiber material in a ratio of 1 contains at least 50 wt% or more, and non-woven
Needle punch or high pressure liquid
The nonwoven fabric entangled by the body flow is bonded via a binder, and the surface of the nonwoven fabric layer (2) is subjected to a heat calendering treatment to soften the low-melting-point ultrafine fibers on the surface and adhere (4) between adjacent fibers. Smoothed and air permeability 3-15ml / cm ²
/ sec, the filtration accuracy can be remarkably improved by the entangled denseness of the fine fibers of the nonwoven fabric layer (2) and the regulation of the air permeability, and the softening of the low melting point fine fibers of the filtration surface The fiber-to-fiber bonding (4) reduces fluff, improves dust removal and reduces pressure loss. The woven fabric base (3) maintains the dimensional stability and strength of the filter cloth (1) and can withstand severe use. Therefore, it is particularly suitable for a bag filter.

[Brief description of the drawings]

FIG. 1 is a sectional view of the filter cloth of the present invention.

FIG. 2 is a fiber sectional view showing an example of a conjugate fiber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filtration cloth 2 Nonwoven fabric layer 3 Fabric base cloth 4 A component 5 B component 6 Splittable composite fiber 7 Hot melt agent 8 Adhesion between fibers

Claims (1)

(57) [Scope of request for utility model registration] [Claim 1] A splittable conjugate fiber is formed on a woven fabric base fabric having a basis weight of 200 to 800 g / m ² by a thickness of 0.5.
An ultrafine fiber material in which a low melting point ultrafine fiber having a denier or less and a high melting point ultrafine fiber are mixed at a ratio of 1: 1 is used in at least 50 parts.
% By weight and the fibers constituting the nonwoven fabric
A nonwoven fabric having a basis weight of 60 to 250 g / m ² entangled by a needle punch or a high-pressure liquid flow is joined via a binder, and the surface of the nonwoven fabric is subjected to a heat calendering treatment to soften the low-melting-point ultrafine fibers on the surface and to form adjacent fibers A filter cloth characterized in that the gap is adhered and smoothed, and the air permeability is suppressed to 3 to 15 ml / cm ² / sec.