JPH0526122U - Filter cloth - Google Patents

Abstract

(57) [Abstract] [Purpose] In a filter cloth for fluid, it improves the dust collection efficiency of fine particles and the dust removal property without lowering the strength of the filter cloth, and prolongs the replacement cycle of the filter cloth. [Structure] A woven fabric base fabric with an ultrafine fiber of 0.5 denier or less composed of a low melting point component and a high melting point component as a nonwoven fabric layer (2)
It is joined to the surface of (3) to form a filtration surface, and the filtration surface side is heat calendered to bond the fibers by softening the low melting point component of the surface (8) to smooth the surface and improve air permeability. Was suppressed to 3 to 15 ml / cm ² / sec and the filter cloth (1) was excellent in dimensional stability and strength.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a filter cloth for a bag filter suitable for capturing and collecting fine dust in a fluid.

[0002]

[Prior Art]

 The filter cloth used to collect the fine dust in the gas, such as a bag filter, requires high strength and morphological stability as well as denseness, so that the filter cloth has conventionally been made of heavy fabric or Nonwoven fabric is used. However, in recent years, more accurate dust collection performance has been required in various fields, and it is difficult for conventional filter cloths to meet these requirements, and therefore filter cloths with high filtration accuracy are required. ing. In response to such a demand, for example, as shown in JP-A-3-60712, the average fineness of 0. A filter cloth laminated with a non-woven fabric sheet made of ultrafine fibers of 2 denier or less has been proposed.

[0003]

[Problems to be solved by the device]

 However, a filter cloth obtained by laminating a non-woven fabric sheet made of ultrafine fibers with an average fineness of 0.2 denier or less on the surface of the needle felt is excellent in strength and morphological stability, and also has a high dust collection efficiency for fine particles. Although it has advantages, the filtration surface (dust supply side) is only smoothed by the pressure applied during lamination, and it is not always satisfactory in terms of removing dust adhered to the filtration surface. The goodness and badness of the removal property affect the pressure loss and the replacement cycle of the filter cloth. The present invention has been made for the purpose of improving the above problems.

[0004]

[Means for Solving the Problems]

The present invention uses low-melting point ultrafine fibers and high-melting point ultrafine fibers in at least a part of the non-woven fabric that is bonded onto the woven base fabric, and softens the low-melting point ultrafine fibers during the smoothing process on the filtration surface side with a heat roll. As a result, the air permeability was suppressed and the smoothness of the filtration surface was further improved, improving the dust removal property. That is, the present invention is an ultrafine fiber in which a low melting point ultrafine fiber having a thickness of 0.5 denier or less and a high melting point ultrafine fiber are mixed in a ratio of 1: 1 on a woven fabric having a basis weight of 200 to 800 g / m ^2. A non-woven fabric having a basis weight of 60 to 250 g / m ² containing at least 50% by weight of the fibrous material is joined with a binder, and the non-woven fabric surface is subjected to thermal calendering to soften the low melting point component of the filtration surface and adjoin it. By bonding the fibers to each other, the filtration surface was made smooth, and the air permeability was suppressed to 3 to 15 ml / cm ² / sec to give a filter cloth.

An ultrafine fiber material of 0.5 denier or less in which low melting ultrafine fibers and high melting ultrafine fibers are mixed in a ratio of 1: 1 can be obtained by dividing a splittable conjugate fiber. Examples of the constituent components of the splittable conjugate fiber include polyolefin-based polymers such as polyethylene, polypropylene, poly-4-methylpentene-1, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, or copolymers. It can be appropriately selected from a polymer, a polyester-based polymer or copolymer such as polyethylene terephthalate and polybutylene terephthalate, and a polyamide-based polymer or copolymer such as nylon 6, nylon 66 and nylon 12. It is preferable that it is composed of two or more components having a melting point difference of 20 ° C. or higher. There are various conceivable fiber cross-sectional shapes of the splittable conjugate fiber, and although not particularly limited, a radial type is preferable.

The non-woven fabric layer serving as a filtration surface has a basis weight of 60 to 250 g / m ² containing 50% by weight or more, preferably 85% by weight or more, of ultrafine fibers of 0.5 denier or less obtained by dividing the splittable conjugate fiber. Nonwoven fabrics are preferred. The non-woven fabric is formed by the card method, the cross-layer method, the random webber method, the wet papermaking method, the dry or wet heat bonding method, the needle punch method, the high-pressure liquid flow method, etc., but the division is insufficient at this point. The product is further subjected to treatments such as needle punching, high-pressure liquid flow treatment, and ultrasonic treatment, but high-pressure liquid flow treatment is particularly preferable, and the discharge water pressure is 30 to 200 kg / cm ² , preferably 80 to 150 kg / cm ² . ^2. It is preferable to perform the treatment at a speed of 1 to 5 m / min at least twice for each of the front and back sides. If the discharge water pressure is less than 30 kg / cm ² and the speed is faster than 5 m / min, the division will be insufficient and the particulate collection efficiency will not be improved. If the discharge water pressure is greater than 200 kg / cm ² and the speed is less than 1 m / min, it will be over-treated. It is uneconomical. In addition, the non-woven fabric can be mixed with other fibers of less than 50% by weight. As the other fibers, natural fibers such as cotton and hemp, semi-synthetic fibers such as rayon, synthetic fibers such as polyolefin, polyester and polyamide. It may be appropriately selected from among these depending on the intended use. If the ultrafine fibers are more than 0.5 denier, the content of the ultrafine fibers is less than 50% by weight, and the basis weight is less than 60 g / m ² , fine particles cannot be expected to be captured. On the contrary, even if the basis weight of the above-mentioned non-woven fabric is set to 250 g / m ² or more, the efficiency of capturing fine particles is not improved so much and the cost is increased.

The woven base fabric may be a base fabric composed of fibers having a higher melting point than the low melting point component of the non-woven fabric layer, for example, synthetic fiber spun yarn of 1.5 denier or more, multifilament, and filtration. A woven fabric that can maintain strength and form is preferable as the cloth. As the synthetic fiber used for the woven base fabric, a single component fiber or a composite fiber such as a parallel type, a core-sheath type, a split type or a sea-island type can be used. Are preferable, and for example, fibers such as the above-mentioned polyolefin, polyester, polyamide, etc. may be used. The basis weight of the woven base fabric is 200 to 800 g / m ² , preferably 400 to 600 g / m ² , and when the basis weight is less than 200 g / m ^2, it is difficult to maintain the shape as a filter fabric, and 800 g / m 2 ^If it is larger than ² , the filter cloth becomes bulky.

The filter cloth of the present invention is formed by intercalating a hot-melting agent between the non-woven fabric obtained above and the woven fabric base, and subjecting it to thermal calendering. During this heat calendering, the low melting ultrafine fibers on the surface of the non-woven fabric layer are softened or partially melted to be bonded to the adjacent fibers, and the softening or melting degree is adjusted to adjust the air permeability to 3 to 15 ml / cm ² / sec, preferably. Is a filter cloth suppressed to 5 to 10 ml / cm ² / sec. Low melting point If the softening and melting of the ultrafine fibers becomes excessive, the surface becomes resinous and the air permeability becomes less than 3 ml / cm ² / sec, and the dust removal property improves, but the pressure loss during use increases and the motor The load is high and it is necessary to replace the filter cloth in a short period of time. If the softening point of the low melting point ultrafine fibers on the surface of the non-woven fabric layer is insufficient, fiber-to-fiber bonding cannot be achieved and the air permeability exceeds 15 ml / cm ² / sec and the pressure loss during use is small, but the surface is smooth. As the property becomes insufficient, the dust removal efficiency of the dust adhering to the non-woven fabric surface deteriorates, and the dust collection efficiency decreases.

As the hot-melt agent for joining the non-woven fabric layer and the woven fabric, a commonly used low-melting agent such as polyamide, polyester, or polyolefin may be used, which is particularly used for the filter cloth. A hot-melting agent of the same family as the material is preferable.

The conditions for the thermal calendaring for joining the non-woven fabric layer and the woven base fabric are as follows: a heat roll and a normal temperature roll in the range from the softening point of the low melting point ultrafine fibers of the non-woven fabric layer to the melting point of the high melting point component It is advisable to use two calender rolls, the non-woven fabric layer side as a heat roll, and a linear pressure of 50 to 100 kg / cm at a speed of 3 to 7 m / min. When the linear pressure is 100 kg / cm or more and the speed is less than 3 m / min, the low melting point ultrafine fibers are excessively softened and made into a molten resin, and the air permeability is lowered. 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 ultrafine fibers on the surface of the non-woven fabric will be insufficient and interfiber bonding will not be possible, resulting in a smooth and dust-dispelling property. Can't do with the surface. .

[0011]

[Action]

 The filter cloth of the present invention has strength and dimensional stability with a woven base cloth, and contains the ultrafine fibers of 0.5 denier or less forming the filter surface (dust supply side). Fine dust. The smooth surface formed by the fiber attachment by softening the low-melting ultrafine fibers suppresses fluff, improves the dust collection efficiency of fine particles, and improves the dust removal property.

[0012]

【Example】

Referring to the drawings showing the embodiments of the present invention, in FIG. 1, (1) shows a filter cloth, (2) shows a non-woven fabric layer, and (3) shows a woven base cloth. As shown in FIG. 2, the non-woven fabric layer (2) has nylon 6 (melting point 214 ° C.) as the A component (4) which becomes the low melting point ultrafine fiber and B component (5) which becomes the high melting point ultrafine fiber. Polyethylene terephthalate (melting point 256 ° C) are alternately arranged in a radial pattern. Splittable conjugate fibers (16 splittables) are melt-composite-spun at a spinning temperature of 290 ° C and stretched 3 times in warm water at 75 ° C. It was cut into 3 denier and 45 mm split-type composite fiber (6) staples. 100% by weight of this split-type composite fiber (6) was used to make a card web with a card machine, and then water pressure was 150 kg / cm ² , Split-type composite fiber (6) is treated with high-pressure liquid flow at a speed of 3 m / min three times for each of the front and back sides, and the splitting type composite fiber (6) has a low melting point of A component (4) and a high melting point of B component (5) Divide into ultrafine fibers (thickness 0.19 denier) and entangle the fibers Using basis weight 120 g / m ² nonwoven fabric.

As the woven base fabric (3), a plain weave having a basis weight of 400 g / m ² is used, which is formed by weaving three twisted polyester spun yarns of cotton count 5 ^S for warp and weft. It was

Then, a low-melting-point polyester hot-melt agent (7) having a basis weight of 25 g / m ² is interposed between the non-woven fabric layer (2) and the woven base fabric (3), and the non-woven fabric layer (2) side is heated to a temperature of The surface of the non-woven fabric layer (2) was calendered at a linear pressure of 100 kg / cm and a speed of 4 m / min using a 195 ° C heat roller and a calender roller with the woven base fabric (3) side at room temperature. Low melting point on the side Softening the ultrafine fibers to bond adjacent fibers (8) and melting the hot melt agent (7) to integrate the non-woven fabric layer (2) and woven base fabric (3) into a filter cloth (1) The air permeability of this filter cloth (1) was 6.2 ml / cm ² / sec.

Comparative Example 1 A non-woven fabric layer of Example was made to have a basis weight of 50 g / m ² , and the same woven fabric fabric as in Example was used to obtain a filter fabric in the same manner as in Example. The air permeability of this filter cloth is 9. It was 6 ml / cm ² / sec.

[Comparative Example 2] A non-woven fabric having the same basis weight of 120 g / m ² as in the example was used as the non-woven fabric layer, and the hot-melting agent having a low melting point was interposed on the same woven base fabric as in the example, and the heat calender roller was used. 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 was 18 ml / cm ² / sec.

“Table 1” shows the filtration performance evaluation results of the filter cloths of Examples and Comparative Examples 1 and 2.

The filtration performance was evaluated as follows. Ten types of JIS test dust were used and tested with a pulse type dust collector. The conditions of the test machine were set as follows. Air volume 2.5 m ³ / min, filtration area 0.66 m ² , pulse interval 2 min, 0.1 sec / 1 pulse, pulse pressure 3 kg / cm ² , test time 7 hr, temperature (room temperature) for acceleration and primary adhesion layer In order to form the film, dust was not removed until the pressure on the surface of the filter cloth reached ΔP = 150 mmH ₂ O.

Dust leakage amount (g): Dust that has passed through the filter cloth and is collected by a filter paper capable of collecting up to 0.1 μm of dust. Dust collection efficiency (%): Inlet dust concentration A (g / m ³ ) was measured from the dust feeder, and outlet dust concentration B (g / m ³ ) was measured by the air volume passing through the filter cloth and the above-mentioned dust leakage amount. , Dust collection efficiency (%) = [1- (B / A)] × 100. Permeability decrease (%): The air permeability C (ml / cm ² / sec) before the above test and the air permeability D (ml / cm ² / sec) after the test were measured, and the air permeability decrease (%) = [ 1- (D / C)] × 100. Pressure loss (mmH ₂ O): the test ΔP = 150mmH ₂ maximum value after O. Dust removal property [Amount of dust adhered (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 device]

The filter cloth (1) of the present invention has a low-melting point ultrafine fiber having a thickness of 0.5 denier or less and a high-melting point ultrafine fiber on a woven fabric base cloth (3) having a basis weight of 200 to 800 g / m ^2. A non-woven fabric containing at least 50% by weight or more of the ultrafine fiber material mixed in a ratio of 1 is joined through a binder, and the non-woven fabric layer (2) is subjected to a thermal calendering treatment to the above-mentioned low melting point of the surface. Since the component is softened and the adjacent fibers are bonded (4) to make it smooth, and the air permeability is suppressed to 3 to 15 ml / cm ² / sec, the entangled denseness of the ultrafine fibers of the nonwoven fabric layer (2) The filtration accuracy can be significantly improved by controlling the air permeability and air permeability.However, the fluff is suppressed by the interfiber bonding (4) due to the softening of the low-melting ultrafine fibers on the filtration surface, which improves the dust removal performance and reduces the pressure loss. Is reduced. And since the woven base fabric (3) retains the dimensional stability and strength of the filtration fabric (1), it can withstand severe use. Therefore, it is particularly suitable for bag filters.

[Brief description of drawings]

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

FIG. 2 is a fiber cross-sectional view showing an example of a composite fiber.

[Explanation of symbols]

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

Claims (1)

[Scope of utility model registration request] 1. An ultrafine fiber in which a low melting point ultrafine fiber having a thickness of 0.5 denier or less and a high melting point ultrafine fiber are mixed at a ratio of 1: 1 on a woven fabric having a basis weight of 200 to 800 g / m ^2. Fabric weight 60-25 containing at least 50% by weight of material
A non-woven fabric of 0 g / m ² is joined via a binder, and the non-woven fabric surface is subjected to a heat calendering treatment to soften the low melting point component on the surface and to bond and smooth adjacent fibers,
A filter cloth having an air permeability of 3 to 15 ml / cm ² / sec.