JP2554254Y2 - 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 suitable for a bag filter used for filtering gas.

[0002]

2. Description of the Related Art Fabrics and felts are mainly used as conventional filter cloths for bag filters, but it is difficult to collect fine particles with a mere fabric or felt. For this reason, as disclosed in JP-A-3-60712, a filter cloth has been proposed 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 as disclosed in JP-A-3-60712. .

[0003]

[Problems to be Solved by the Invention] However, a filter cloth obtained by laminating a nonwoven sheet made of ultrafine fibers having an average fineness of 0.2 denier or less on the surface of a needle felt has a good dust collection efficiency of fine particles, but has a good dust removing property. Since the filter cloth is bad, clogging occurs and the pressure loss increases early, so that the filter cloth must be replaced in a relatively short time. SUMMARY OF THE INVENTION An object of the present invention is to improve the efficiency of collecting fine particles and removing dust by improving the filtering surface, to delay the rise of pressure loss, and to extend the replacement cycle of the filter cloth.

[0004]

According to the present invention, in order to achieve the above object, low-melting-point ultrafine fibers are mixed in a fiber group constituting a dust supply side (hereinafter sometimes referred to as a filtration side) of a filter cloth. Then, the low-melting point ultrafine fibers exposed on the filtration surface were made into a molten resin to smooth and densify the filtration surface.

[0005] That is, the filter cloth of the present invention has a split type composite fiber.
At least 50% by weight or more of ultrafine fibers of 0.5 denier or less in which ultrafine fibers of the low melting point component and ultrafine fibers of the high melting point component are mixed at a ratio of 1: 1 are formed at least on the dust supply side surface , And the constituent fibers are needle punched
Or a basis weight of 100 to 150 entangled by a high-pressure liquid flow.
g / m ² non-woven fabric layer, the basis weight of synthetic fibers of 1.5 denier or more including the base fabric is laminated on the base layer of the non-woven fabric of 200 to 450 g / m ² , At least a part of the low-melting ultrafine fibers on the supply side is melted and resinized to smooth the filtration surface, and the air permeability is densified to ² to 10 ml / cm ² / sec.

As the ultrafine fibers of 0.5 denier or less in which the ultrafine fibers of the low melting point component and the ultrafine fibers of the high melting point component are mixed, a splittable conjugate fiber is preferable, but is not particularly limited. As constituent components of the conjugate fiber, for example, polyethylene, polypropylene, poly 4-methylpentene-1,
Polyolefin polymers or copolymers such as ethylene-vinyl alcohol copolymers and ethylene-vinyl acetate copolymers; polyester polymers or copolymers such as polyethylene terephthalate and polybutylene terephthalate; nylon 6, nylon 66, nylon Although it can be appropriately selected from polyamide-based polymers or copolymers such as No. 12 and the like, it is preferable to comprise two or more components having a melting point difference of 20 ° C. or more. The invention is not limited to the above-mentioned polymer or copolymer. Various fiber cross-sectional shapes of the splittable conjugate fiber can be considered and are not particularly limited, but a radial type is preferable.

[0007] The layer on the filtration surface side is composed of 50% by weight or more, preferably 85% by weight, of fibers obtained by splitting the splittable bicomponent fiber having the above-mentioned melting point difference and making it ultrafine to 0.5 denier or less.
It is preferable to use a nonwoven fabric having a basis weight of 100 to 120 g / m ² containing not less than 100% by weight. In this nonwoven fabric, the splittable conjugate fiber is formed into a nonwoven fabric by a card method, a cross-layer method, a random webber method, a wet papermaking method, a dry or wet heat bonding method, a needle punch method, a high-pressure liquid flow method, etc. Insufficiency of the composition may be further subjected to a treatment such as needle punching treatment, high-pressure liquid flow treatment, or ultrasonic treatment. Particularly, high-pressure liquid flow treatment is preferable for division and entanglement of fibers.

The conditions for the high-pressure liquid flow treatment are as follows: discharge water pressure 30 to 200 kg / cm ² , preferably 80 to 150 kg / c
It is desirable to perform the treatment at least twice on each of the front and back sides at m ² and a speed of 1 to 5 m / 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. The non-woven fabric may be mixed with natural fibers such as cotton and hemp, semi-synthetic fibers such as rayon, and other fibers such as polyolefin, polyester, and polyamide at less than 50% by weight. If the thickness of the ultrafine fibers exceeds 0.5 denier, or if the mixing ratio of the ultrafine fibers is less than 50% by weight, desired surface resinification cannot be obtained, and the basis weight of this nonwoven fabric layer is less than 100 g / m ² . If it is, dust collection is not expected. And even if the basis weight is 150 g / m ² or more, the efficiency of collecting fine particles does not increase so much and the cost is only high.

As the base material layer, a nonwoven fabric in which synthetic fibers having a melting point of 1.5 denier or more having a melting point higher than that of the low melting point ultrafine fibers are entangled with a base cloth is preferable. As the synthetic fiber of the base layer, any of a single fiber or a composite fiber such as a parallel type, a core-sheath type, a split type, and a sea-island type can be used. A single fiber having a denier of 3 to 3 deniers is preferable, and the above-mentioned components such as polyolefin, polyester, and polyamide may be used. The basis weight of the base material layer is 200 to 450 g / m ² , preferably 300 to 450 g / m ² .
If it is 400 g / m ² and the basis weight is less than 200 g / m ^2, it is difficult to maintain the form as a filter cloth, and if it exceeds 450 g / m ² , the filter cloth becomes bulky.

[0010] A hot melt agent is interposed between the non-woven fabric layer and the base material layer obtained as described above, and they are integrated by heat calendering. At this time, a part of the low-melting point ultrafine fibers on the surface of the nonwoven fabric layer is melted to resin to adjust the air permeability.
10ml / cm ² / sec, preferably a filter cloth 5~8ml / cm ² / sec. Air permeability pressure loss is increased is less than 2ml / cm ² / sec, dust brushing resistance becomes greater than 10ml / cm ² / sec, the dust collection efficiency is lowered. As the hot melt agent for joining the nonwoven fabric and the substrate layer constituting the filtration surface, polyamide-based, polyester-based, and polyolefin-based hot melt agents can be used without particular limitation, but are similar to the fiber material used for the filter cloth. Systems are preferred.

The conditions of the heat calendering are as follows. Two calender rolls, a hot roll and a normal-temperature roll, having a melting point of the low-melting-point ultrafine fiber component of the nonwoven fabric layer and a melting point of the high-melting-point ultrafine fiber component thereof are used. It is preferable that the side is treated as a hot roll at a linear pressure of 50 to 100 kg / cm and a speed of 3 to 7 m / min. If the linear pressure is less than 50 kg / cm and the speed is 7 m / min or more, the filtration surface becomes insufficiently molten and the air permeability exceeds 10 ml / cm ² / sec. , that the dust collection efficiency is make low. The linear pressure is 100kg / c
If it is higher than m and the speed is 3 m / min or less, the filtration surface becomes excessively molten resin, the air permeability becomes 2 ml / cm ² / sec or less, and the pressure loss of the filter cloth increases.

[0012]

[Function] The filter cloth of the present invention is divided into multiple parts on the dust supply side.
The ultrafine fibers of a low melting point component and a high melting point component of 0.5 denier or less that if fibers are formed by dividing seen including, and constituent fibers same
By a needle punch or the action of high pressure liquid flow.
By arranging the non-woven fabric layer which is entangled and further converting at least a part of the low melting point ultrafine fiber component in the non-woven fabric layer on the surface into a molten resin, the fuzz on the surface is suppressed, the surface is smoothed, and the filtration cloth is ventilated. The degree can be between ² and 10 ml / cm ² / sec. Then the smoothed through the gas of the filtering surface by adjusting in this manner, improved fine dust collecting efficiency, the dust brushing property becomes better, it is possible to extend the replacement period of the filter cloth.

[0013]

1 is an enlarged cross-sectional view of the filter cloth of the present invention in the longitudinal direction, wherein (1) is a filter cloth, (2) is a nonwoven fabric layer, and (3) is a base material layer. The fibers of the non-woven fabric layer (2) have a fiber cross section as shown in FIG. 2 (however, 16 divisions), and a low melting point nylon 6 as the A component (9) and a high melting point polyethylene terephthalate as the B component are used. It is melt-composite extruded and spun at a spinning temperature of 290 ° C., stretched three times in warm water at 75 ° C., and cut to obtain a 3-denier, 45 mm long splittable conjugate fiber (8). ing. And this split type composite fiber
(8) was made into a card web by a card machine using 100% by weight, and subjected to a high-pressure liquid flow treatment 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 form a nonwoven fabric layer (2) having a basis weight of 120 g / m ^2. did. At this time, the A component (9) and the B component (10) of the composite fiber (8) were split, and each was split into ultrafine fibers (5) having an average thickness of 0.19 denier.

As the base layer (3), a felt having a basis weight of 400 g / m ^{2 made} of polyethylene terephthalate fiber (2 denier in thickness) having a base cloth (6) [trade name: FT-040]
8, manufactured by Nippon Felt Industry Co., Ltd.].

Then, a hot-melt agent of low melting point nylon having a basis weight of 20 g / m ² is provided between the nonwoven fabric layer (2) and the base material layer (3).
(7), the non-woven fabric layer (2) side is a heat roller at a temperature of 195 ° C., the base material layer (3) side is a room temperature roller, and the linear pressure is 100 kg / c.
m, calendering at a speed of 4 m / min to convert a part of the low melting point component into molten resin (4) and hot melt agent (7)
And the nonwoven fabric layer (2) and the base material layer (3) were integrated into a filter cloth (1) having an air permeability of 6 ml / cm ² / sec.

Comparative Example The basis weight of the nonwoven fabric layer of the example was 8
It was set to 0 g / m ^2, and a filter cloth was formed by the same means as in the example using the same substrate layer as in the example.

Table 1 shows the results of evaluating the filtration performance of the filter cloth of the example and the filter cloth of the comparative example.

The filtration performance was evaluated as follows. Ten kinds of JIS test dusts were used and tested with a pulse-type dust collector. 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 removing dust until the pressure on the filter cloth surface 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 removal property (dust adhesion amount (g / m ² )): The weight of the dust after 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 is a split-type composite fiber.
The ultrafine fibers of 0.5 denier or less (5) in which the ultrafine fibers of the low melting point component and the ultrafine fibers of the high melting point component are mixed at a ratio of 1: 1 are formed at least on the dust supply side.
0% by weight or more and constituent fibers are needle pan
Weight or weight entangled by the action of high pressure liquid flow 1
A nonwoven fabric layer (2) of 100 to 150 g / m ² and a base fabric (6) and a basis weight of synthetic fiber of 1.5 denier or more including 200 to 200 g / m ²
A substrate layer (3) of 450 g / m ² nonwoven fabric is laminated and integrated, and at least a portion of the low melting point ultrafine fibers on the dust supply side is made into a molten resin (4) and smoothed, and air permeability is reduced. Is adjusted to ² to 10 ml / cm ² / sec, so that the filtration accuracy is remarkably improved by the ultrafine fibers of the nonwoven fabric layer (2) forming the filtration surface side, and the low melting point ultrafine fibers on the filtration surface side The fuzz is suppressed by the melt resinification, and the dust removal property and the dust collection efficiency of fine particles are improved by regulating the air permeability, so that the replacement cycle of the filter cloth can be greatly extended, which is excellent. It is effective. Therefore, the filter cloth (1) of the present invention is particularly suitable for bag filters.

[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 Base material layer 4 Melt resinization 5 Microfiber 6 Base fabric 7 Hot melt agent 8 Splittable composite fiber 9 A component 10 B component

Claims (1)

(57) [Scope of request for utility model registration] An ultra-fine fiber having a low melting point component and an ultra-fine fiber having a high melting point component formed by dividing a splittable conjugate fiber are 1: 1.
The ultrafine fibers of 0.5 denier or less mixed at a ratio of 50% by weight or more exist on at least the dust supply side , and
Needle punch or high pressure liquid flow
Entangled with a nonwoven layer having a basis weight of 100 to 150 g / m ² comprising, in weight per unit area consisting of 1.5 denier or more synthetic fibers include base fabric and a base material layer of the nonwoven 200~450g / m ² is laminated structure And at least a part of the low melting point ultrafine fiber on the dust supply side is melted and smoothed, and the air permeability is 2 to 2.
A filter cloth characterized by 10 ml / cm ² / sec.