JP3233988B2 - Filter cloth and method for producing the same - 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 applied to gas filtration and a method for producing the same.

[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]

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 good dust collection efficiency of fine particles, but has a low dust removal 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. In addition, the needle felt and the microfiber nonwoven sheet, which are the sheet base materials, are laminated with a hot-melt type adhesive or by melting the surface layer of the needle felt. For example, when used as a bag filter, the temperature of the filter cloth increases. Due to such factors, the bonding surface is softened, and delamination occurs partially due to dust sweeping vibration, which often causes a situation in which the device cannot be used early.

[0004] It is an object of the present invention to improve the collection efficiency of fine particles and the dust removing property by improving the filtration surface,
It delays the rise of pressure loss and extends the exchange cycle of the filter cloth.Furthermore, the ultrafine fiber layer constituting the filter surface is entangled and integrated with the sheet substrate without using an adhesive, and filtration without delamination is performed. It is an object of the present invention to provide a fabric and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a layer constituting a dust supply side (hereinafter sometimes referred to as a filtration side) of a filter cloth is formed by a group of fibers obtained by dividing a splittable conjugate fiber. The object has been solved by entanglement of the conjugate fiber with the sheet base material and by smoothing the filtration surface formed of the ultrafine fibers.

Namely filter cloth of the present invention, on one surface of the sheet over preparative substrate, average fineness, which is integrated by the sheet substrate and the fiber entangled nonwoven layer according to the following ultrafine fibers 0.5 denier distribution is filtered surface is formed, characterized in that the surface of the nonwoven fabric layer of the ultrafine fibers is smoothed, also in the manufacturing method of the filter cloth, divided into one surface of the sheet over preparative substrate A split type composite fiber web having an average fineness of 0.5 denier or less is superimposed, needle-punched from the web side to entangle the split type composite fiber web with the sheet substrate, and then a high pressure liquid is applied from the web side. Flow treatment is performed to divide the splittable conjugate fiber, form a nonwoven fabric layer of ultrafine fibers on the surface of the sheet substrate, and form a filtration surface after drying.
The web surface is smoothed by a heating roll heated to such an extent that the ultrafine fibers do not melt .

[0007] 0.5 to form the filtration surface of the filter cloth of the present invention
As the ultrafine fiber having a denier or less, a staple of a splittable conjugate fiber in which two different components are alternately present is preferable. As the 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 12
Although it can be appropriately selected from polyamide-based polymers or copolymers such as those described above, it is particularly preferable that the composition be composed of two components having a melting point difference of 20 ° C. or more. The fiber cross-sectional shape of the splittable conjugate fiber is not particularly limited, but a radial type which is easily split by a high-pressure water flow is preferable.

[0008] layer of the filtration surface, after entangling integrated both subjected to needle punching by superposing a web of splittable conjugate fibers onto the sheet over preparative substrate, high-pressure water from the web side of the splittable conjugate fiber It is preferable to divide the splittable conjugate fiber to make it ultrafine, and then to perform roller processing to smooth the surface.

[0009] As another method, the splittable conjugate fiber is divided into ultrafine fibers of 0.5 denier or less and at least 50 deniers.
A web comprising wt% superimposed on the sheet over preparative substrate, after both were entangled integrally subjected to needle punching, the surface may be smoothed by a roller machining.

The conditions of the high-pressure water flow treatment for splitting the splittable conjugate fiber include a discharge water pressure of 30 to 200 kg / cm ² ,
It is preferably 80 to 150 kg / cm ² , and the moving speed of the object is preferably about 1 to 5 m / min. Discharge water pressure is 30kg / c
less than m ^2, the speed is insufficient dividing faster than 5 m / min,
If the discharge water pressure is higher than 200 kg / cm ^2, it is excessively processed, which is uneconomical.

If the thickness of the ultrafine fibers exceeds 0.5 denier, or if the composition ratio of the ultrafine fibers in the nonwoven fabric layer forming the filtration surface is less than 50% by weight, a filtration surface with a desired accuracy cannot be obtained.
If the basis weight of the nonwoven fabric layer is less than 100 g / m ² , dust collection cannot be expected. The basis weight since no sufficiently enhanced fine particle dust efficiently even a 150 g / m ² or more, the basis weight of the microfiber layer is about 100 to 150 g / m ² is economically.

[0012] As the sheet substrate, woven fabric weight obtained by interposing a base fabric of the city sales of needle punching the nonwoven fabric and 300 to 500 g / m ^2, interwoven with Parokku yarns or multifilament yarns of low yarn count fabric Is preferably applicable.

The air permeability of the filter cloth is, for example, ^{2 to} 10 ml / cm ² / sec, preferably ^{2 to} 6 ml for a bag filter.
The range of / cm ² / sec is good. 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 conditions for the roll processing for smoothing the filtration surface, two calender rolls, a hot roll and a normal temperature roll, which are heated to such an extent that the ultrafine fibers forming the filtration surface are not melted, are used. The ultrafine fiber layer side may be treated as a heat roll with a linear pressure of 50 to 100 kg / cm and a speed of 3 to 7 m / min, and the smoothness and air permeability can be adjusted by adjusting the linear pressure of the roll.

[0015]

According to the filter cloth of the present invention, the non-woven fabric layer containing the ultrafine fibers having a thickness of 0.5 denier or less constituting the dust supply side surface, that is, the filter surface side, is formed on the sheet base without using an adhesive. Since the fiber entanglement is integrated with the sheet substrate, the temperature of the filter cloth rises during use, and delamination does not occur even if the filter cloth is frequently shaken off by dust at the temperature rise. The smoothed filtration surface of the aggregate layer of the microfibers improves the particulate collection efficiency, improves the dust removal property, and contributes to the extension of the filter cloth replacement cycle.

[0016]

EXAMPLES Example 1 FIG. 1 is an enlarged cross-sectional view of a filter cloth of the present invention in the longitudinal direction, wherein (1) is a filter cloth, and (2) is a nonwoven fabric layer of ultrafine fibers forming a filter surface. And (3) are sheet substrates. The non-woven fabric layer (2) has a fiber cross section as shown in FIG. 4 (however, divided into 16), and is made of a flat material comprising polyester as the component (8) and nylon-6 as the component (9).
The split-fiber composite fiber (10) having an average fineness of 3 deniers is composed of microfibers having an average fineness of 0.19 denier when divided, and the sheet substrate (3) has a reinforcing base cloth (4). Needle-punched nonwoven fabric with a basis weight of 400 g / m ^{2 made} of polyethylene terephthalate fiber (thickness: 2 denier) [trade name: FT0408. Manufactured by Nippon Felt Industry Co., Ltd.], which are joined and integrated by fiber entanglement by needle punching means. The surface of the non-woven fabric layer of microfibers (2) is processed with a hot roll heated to about the softening and melting temperature of the low melting point component side (B component) of the microfibers, so that the smooth filtration surface without fluff (5) It has become.

The filter cloth (1) of the above [Example 1] was produced as follows. The split-split conjugate fiber as exemplified in FIG. 4, that is, polyester as component A (8) and component B
As (9), a splittable composite fiber obtained by disposing nylon-6 is melt-composite-extruded, spun three times, and cut to obtain a flat composite fiber.
After preparing a splittable conjugate fiber (10) having a uniformity of 3 denier and a length of 45 mm, a card web is formed by a carding machine using 100% by weight of the splittable conjugate fiber (10). The web was then made into a web sheet with a basis weight of about 125 g / m ² , and as shown schematically in FIG.
A web sheet (11) is overlaid on (3) and needle-punched from the web side to entangle the splittable conjugate fiber web with the sheet substrate (3). While moving at a speed of 4 m / min, a water pressure of 150 kg / c is applied from a split type composite fiber web side by a high pressure liquid flow treatment device (13) in which a number of fine nozzles are arranged in the width direction.
performing division processing of splittable conjugate fibers with m ^{2, and} the sheet substrate and the nonwoven fabric layer by an average fineness 0.19 denier microfine fibers on the surface of (3) (2) composite nonwoven fabric which is formed (14) None, dried. In the composite non-woven fabric (14) thus obtained, the splittable composite fibers on the surface of the non-woven fabric layer (2) are mostly ultrafine,
In addition, the puncture hole of the needle in the needle punching in the previous process was deleted. Thereafter, a pair of rollers (15) and (16) having a non-woven fabric layer (2) side having a heat roller (15) at a temperature of 185 ° C. and a sheet substrate (3) side having a room temperature roller (16) has a linear pressure of 100 kg / cm. ,
Calendering is performed at a speed of 4 m / min, and the nylon-6 component of the non-woven fabric layer (2) is softened and smoothed by a hot roll (15) to obtain a filter cloth (1) having a smooth filtration surface (5). did.
The air permeability of the obtained filter cloth (1) was 4.2 ml / cm ² / sec.

[0018] [Example 2] over preparative substrate as a (3), 3 Parokku spun yarn polypropylene fibers of cotton count 5 ^S
This twisted yarn was used for the warp and the weft, and a heavy plain fabric having a warp density of 16 yarns / inch and a weft density of 15 yarns / inch was used. Then, in the same manner as in Example 1 above, a split-type composite fiber web sheet having a basis weight of about 125 g / m ² was superposed on the sheet base material (3), needle-punched, followed by high-pressure water-flow treatment, and after drying, By performing calendering, the fibers of the nonwoven fabric layer (2) are entangled and integrated with the sheet substrate (3) as shown in FIG. 5) became a smooth filter cloth (1).

In the obtained filter cloth (1), the nonwoven fabric layer (2) on the filter surface is composed of ultrafine fibers, the surface of which is extremely smooth, is more flexible than that of Example 1, and has a ventilation The degree was 2.1 ml / cm ² / sec.

Comparative Example A web sheet having a basis weight of 125 g / m ^{2 was} prepared using the splittable conjugate fiber of the example, and the web sheet was subjected to a high-pressure water flow treatment to make the splittable conjugate fiber extremely fine and to entangle the fibers. Then, the non-woven fabric was formed into an ultra-fine fiber non-woven fabric. The non-woven fabric was bonded to one surface of the sheet substrate of Example 1 with a hot melt agent, and then calendered in the same manner as in Example to filter the ultra-fine fiber non-woven fabric layer. Made with cloth. In addition, as a hot melt agent, [polyamide.
Daiamide 1000 # (Daicel Chemical Co., Ltd.) was used.

The filtering performance of the filter cloths of Example 1 and Comparative Example was as shown in Table 1.

[0022]

[Table 1]

The filtration performance was evaluated as follows. Using 11 kinds of JIS test dusts, a test was conducted with a flat type dust tester (manufactured by the company). The conditions of the testing machine were
The filtration area was set at 44.156 cm ² , the filtration speed was 3 m / mim, and the filtration was performed until the pressure on the cloth surface reached 200 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 adhesion amount (g): Dust weight obtained by measuring the weight of the filter cloth after the test and subtracting the weight of the filter cloth before the test. Dust collection efficiency (%) = Dust collection efficiency = [B / (A +)
B)] × 100. Initial pressure loss (mmH ₂ O): filtration surface pressure when dust is not supplied. D. H. C (g / m ² ): Capability of collecting dust per m ² . Dust brushing rate (%): the filter cloth after the above test, the pressure air of 5kg / cm ² in a direction opposite to the until now 0.25
After a second flow, the dust on the filter cloth was wiped off and the residual dust weight C on the filter cloth was measured, and the dust removal rate (%) = [1- (C / B)] × 100 Calculated.

The delamination strength of the filter cloths of Example 1 and Comparative Example was as shown in Table 2. The peel strength is J
It measured based on IS-L-1089 5.10.

[0026]

[Table 2]

With the filter cloths of Example 1 and Comparative Example,
Practical tests were conducted in a porcelain clay filtration room equipped with a 20 mm, 200 cm long bag filter and a pulse interval of 2 min, 0.1 sec / 1 pulse. The filtration performance and dust removal were both good. However, inspection was conducted at a point in time when the total use time reached 1300 hours. As a result, delamination between the sheet base material and the nonwoven fabric layer was observed in the bag filter of the comparative example, and subsequent use was impossible.
However, no delamination was observed in the bag filter using the filter cloth of Example 1.

[0028]

[Effect of the Invention] filter cloth according to the present invention in this way (1), on one surface of the sheet over <br/> preparative substrate (3), the sheet substrate and (3) are integrated by fiber entanglement A nonwoven fabric layer (2) made of ultrafine fibers having an average fineness of 0.5 denier or less is arranged to form a filtration surface (5), and the surface of the nonwoven fabric layer (2) of the ultrafine fibers is smoothed. There is an extra fine fiber non-woven fabric layer on the filtration side
By (2), the filtration accuracy and the dust collection efficiency of fine particles are remarkably improved, and the filtering surface (5) of the surface layer is smoothed, so that dust can be easily removed. In addition, sheet base
Since (3) and the nonwoven fabric layer (2) of microfibers are joined and integrated by entanglement of the fibers without using an adhesive,
Even if the filter cloth is subjected to a sweeping vibration in a use environment where the temperature is rising, there is no fear of delamination and the useful life of the filter cloth can be greatly extended. Therefore, the filter cloth (1) of the present invention is suitable for bag filters.

Since the nonwoven fabric layer (2) of microfibers is formed by needle-punching a splittable composite fiber web on a sheet substrate and then performing a high-pressure liquid flow treatment, the needle-punching is performed by the high-pressure liquid flow treatment. is erased needle piercing hole of time, the filter cloth is obtained with a proportioned fine pore diameter over the entire surface.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing another embodiment of the present invention.

FIG. 3 is a schematic explanatory view of a method for producing the filter cloth of FIG.

FIG. 4 is a fiber sectional view showing an example of a splittable conjugate fiber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filtration cloth 2 Microfiber nonwoven fabric layer 3 Sheet base material 4 Reinforcement base cloth 5

────────────────────────────────────────────────── ─── Continuing from the front page Examiner Tomoo Niida (56) References Japanese Utility Model No. 5-18615 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 39/00-39 / 20

Claims (3)

(57) [Claims] On one surface of 1. A sheet over preparative substrate, average fineness, which is integrated by the sheet substrate and the fibers entangled filtration surface nonwoven layer is arranged for the following ultrafine fibers 0.5 denier formed is, surface ultrafine fibers of the nonwoven fabric layer of the ultrafine fibers
Is a filter cloth characterized by being smoothed without melting . 2. The fabric weight of the ultrafine fiber layer is 100 to 15
^2. The filter cloth according to claim 1, wherein the amount is 0 g / m ² . 3. A sheet over preparative group one surface in the thickness after the division is less than 0.5 deniers splittable conjugate fiber by overlapping web splittable conjugate fiber is subjected to needle punching from the web side of the material the web is entangled to the sheet substrate, then dividing the splittable conjugate fiber by performing a high-pressure liquid jet process to form a nonwoven layer by ultrafine fiber on the surface of the sheet base material from the web side, after drying, the filtering surface The ultrafine fibers that are forming
A method for producing a filter cloth, wherein the web surface is smoothed by a heating roll heated so as not to melt .