JPH0871336A - Filter cloth using hollow monofilament fiber - Google Patents

Abstract

PURPOSE: To smooth the surface of a filter cloth at high level by calendering under the mild temperature condition and provide good release properties and cleaning properties of cakes by making dense the weaving structure of the filter cloth and improving the performance for collecting fine particles. CONSTITUTION: Hollow monofilament fibers made of synthetic fibers are used for warps 1 and/or wefts 2 of a filter cloth 10. If necessary, the woven filter cloth is calendered after weaving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter cloth using hollow monofilament yarn, and has improved smoothness and compactness suitable for various filters such as pressure filters, vacuum filters and horizontal belt filters. Regarding filter cloth.

[0002]

2. Description of the Related Art In filtration machines such as pressure filters, vacuum filters and horizontal belt filters, solid monofilament yarns have been used as materials for forming warps or wefts of filter cloths. Since solid monofilament yarn has no risk of depositing fine particles or crystals precipitated from the filtrate, the filter cloth itself is less likely to be clogged and the cleaning process cycle can be extended relatively easily. It is possible to operate continuously for a long time.

[0003]

However, in a filter cloth woven from a solid monofilament yarn as a material for forming warp and weft yarns, due to the high rigidity of the solid monofilament yarn, the filter cloth at the entanglement point of the warp yarns and weft yarns is high. Due to the large openings and coarse texture, it becomes difficult to capture the fine particles contained in the filtrate. The filter cloth after weaving needs to be subjected to strong calendering in order to improve the capturing performance of fine particles, and defects such as breakage and melting occur in the solid monofilament yarn due to the strong calendering, and the mechanical strength of the filter cloth is increased. Not only does it decrease, but problems such as shortened service life and increased maintenance man-hours also occur.

In order to avoid strong calendering, as another method, a method has been proposed in which, in weaving a filter cloth, the fineness of the solid monofilament yarn used as a material for forming the warp and the weft is made fine and the woven structure is made dense. However, when this method is adopted, the woven filter cloth itself becomes thin because the warps and wefts themselves are thin, and it is difficult to secure sufficient strength and durability to suppress the occurrence of wrinkles and elongation. Met.

A first object of the present invention is that when a solid monofilament yarn is used as a material for forming a filter cloth, the woven structure becomes coarse due to high rigidity, and fine particles are trapped. It is to prevent performance deterioration and strong calendar processing.

A second object of the present invention is not only that it has a large resistance and resistance to the occurrence of wrinkles and elongation, but it is also used as a filtering means for slurries containing fibrous solids by performing appropriate calendering. In this case, it is an object of the present invention to provide a filter cloth that can keep a high peeling performance for the cake adhered to the surface of the filter cloth and that can be easily washed and regenerated.

[0007]

The filter cloth of the present invention is woven by using hollow monofilament yarns as warp yarns and / or weft yarns. In addition to hollow monofilament yarns for all of the warp yarns and weft yarns, it is also possible to weave the warp yarns and / or weft yarns using aligned yarns of hollow monofilament yarns and solid monofilament yarns. Nylon, polyester and polypropylene are suitable for the material of the hollow monofilament thread, and only one of these materials constitutes the hollow monofilament thread of the warp and / or the weft, or the material of the hollow monofilament of each of the warp and the weft Different types of. For example, nylon is used for the hollow monofilament yarn of the warp, and polyester is used for the hollow monofilament of the weft. Nylon is a general term for polyamide-based synthetic polymers. When high trapping performance of fine particles of the filtrate and high peelability of the cake are required, the filter cloth is calendered. The conditions for calendering at this time may be the same as those for normal calendering.

[0008]

[Function] Since the hollow monofilament yarn is excellent in flexibility, the contact pressure of the warp yarn and the weft yarn at the entanglement point flattens the hollow monofilament yarn to increase the entanglement point contact area, and the mesh opening of the filter cloth is correspondingly increased. Is smaller than in the past, and the performance of capturing fine particles in the filtrate is improved. As a result, while calendar processing of the filter cloth for the purpose of improving the capturing performance of fine particles is not always necessary,
The conditions for calendering may be the same as those for normal calendering even when higher capturing performance is required. After weaving,
By subjecting the hollow monofilament yarn to flattening generally by calendering, it is possible to obtain a high densification of the woven structure and a high trapping performance of fine particles and a high peelability of the cake due to the smoothness of the woven surface.

[0009]

EXAMPLES Hereinafter, five examples shown in FIGS. 1 to 5 and
Embodiments of the present invention will be described based on three comparative examples prepared corresponding to these examples.

FIG. 1 shows a first embodiment of the present invention, in which a warp yarn (1) constituting a filter cloth (10).
Hollow monofilament made of nylon is used for both the weft and the weft (2). As a weaving design, a 5-satin satin weave is adopted, and after weaving, heat setting and calendering are applied to flatten the warp (1) and the weft (2) as a whole, thereby forming a warp (1). The void size at the entanglement point (3) of the weft (2) is narrowed, and the gap (4) between the warp (1) and the gap (3 ′) between the wefts (2) is narrowed. Warp (1) and weft (2)
By using hollow monofilament yarn for both of them and calendering, the filter cloth (10) is smooth and peculiar to using monofilament yarn,
A filter having fine surface characteristics and having a dense liquid passage between the entangled structures of the warp (1) and the weft (2) is completed.

The calendering conditions vary depending on the type and molecular weight of the fiber-forming polymer used as the raw material for the warp (1) and the weft (2), but generally 140 ° C to 200 ° C.
100kgf / cm ~ 15 by roller heated to
1.5 m / min-under the pressure of 0 kgf / cm
By processing at a speed of 5.0 m / min,
Flattening of the yarn (1) and weft (2) and densification of the weave are achieved.

FIG. 2 shows a second embodiment of the present invention, in which the warp yarn (1) constituting the filter cloth (10).
A hollow monofilament yarn made of nylon is used for the weft yarn, while a solid monofilament yarn made of nylon is used for the weft yarn (5).

The mixing ratio of the solid monofilament yarn is set to be equal to or less than the weight of the hollow monofilament yarn used together so as not to obstruct the flattening of the hollow monofilament yarn and the densification of the woven structure of the filter cloth (10).

The nylon hollow monofilament yarn of the warp (1) is flattened by calendering, and the result is shown in FIG. 2 (B).
As shown in (1), the warp (1) is entangled with the weft (5) in such a manner as to enclose the weft (5). As a result, the entanglement gap between the warp yarn (1) and the weft yarn (5) becomes small, and a filter cloth (10) having a dense woven structure can be obtained.

[0015]

[Table 1]

In this case, as shown in Table 1, when the weaving density of the warp threads (1) is made higher than that of the weft threads (5), the flattened warp threads (1) are mostly on the surface of the filter cloth (10). To narrow the gap between the adjacent warp yarns (1).
As a result, the filter cloth (10) has a smooth and dense surface characteristic peculiar to the monofilament yarn, and has a fine liquid passage between the interlaced tissues of the warp (1) and the weft (5). It becomes a material. Filter cloth (10)
The smoothness and the denseness of the front side of the filter cloth (10) are improved, and correspondingly a relatively large liquid passage is formed on the back side of the filter cloth (10). As a result, the filter cloth (10) can be easily cleaned after the filtered cake is peeled off, and the function of preventing clogging is improved.

FIG. 3 shows a third embodiment of the present invention. Contrary to the second embodiment, a solid monofilament yarn made of polyester is used as the warp (6) and the weft (7) is used.
Similarly, a hollow monofilament made of polyester is used. The weft yarn (7) made of hollow monofilament yarn is flattened by calendering, and the gap between adjacent warp yarns (6) is almost the same as the filter cloth of the conventional solid monofilament yarn, but the warp yarn (6) and the weft yarn The woven structure is densified at the confounding point (3) of (7). As a result, the filter cloth (10) shown in FIG.
A filter cloth (10) having the same cleaning properties and improved clogging prevention function as described in (1) is obtained.

In the first, second and third embodiments described so far, the alignment density of the warp yarns (1) and (6) is higher than that of the weft yarns (2), (5) and (7). By using the satin weave structure, the warp yarns (1) and (6) mainly form the surface side of the filter cloth (10). The combination of the use of filament yarn and the woven structure improves the smoothness and the denseness of the surface of the filter cloth (10), and also the warp (1).
(6) and the wefts (2), (5), and (6) are reduced in number so that the adjacent warp (1) or (6)
A liquid passage is formed between them, and the filtration processing capacity is enhanced.

FIG. 4 shows a fourth embodiment of the present invention, in which the weave (1) and the weft (2) of the hollow monofilament yarn made of nylon and having a woven design of plain weave, and the diameter and unit thereof. Alignment density per length, filter cloth (1
Although the thickness of 0), the air permeability, and the pore diameter of the hollow monofilament yarn are different from those of the above-mentioned examples, the filter cloth (10) described in the first example has a cleaning processability and a filtration processability comparable to those of the filter cloth (10). . In this fourth embodiment, the warp (1) and the weft (2) made of hollow monofilament yarn are flattened by calendering after weaving, and the thickness at the entanglement point (3) of the warp (1) and the weft (2) is increased. Achieved narrowing of the void size by utilizing the decrease in
This enhances the ability to capture the fine particles contained in the filtrate to a desired level.

FIG. 5 shows a fifth embodiment of the present invention in which a five-woven satin weave is used as the weave and a hollow nylon monofilament yarn is used as the warp (1). However, the arrangement order of the wefts (2) is
Different from the embodiment, nylon solid monofilament yarn (5) is replaced with nylon hollow monofilament yarn (2).
Is a thread that is pinched from both sides. By adopting a dense weave design in which the hollow monofilament yarn (2) which is one constituent of the weft (2) is closely adhered to both sides of the solid monofilament yarn (5) which is the other weft (2) constituent Thus, the strength in the direction of the weft (2) is improved, and a filter cloth (10) capable of coping with high-pressure filtration is obtained. By disposing the hollow monofilament yarn (2) on the weft (2) side, the entanglement point (3) between the warp (1) and the wefts (2) and (5) is densified, and at the same time, the hollow monofilament yarn (2) ) And the solid monofilament yarn (5) function as a passage for the filtrate, so that the filtering ability of the filter cloth (10) is significantly improved.

The hollow monofilament yarn used in each example had a cross-sectional area ratio of 30% in the hollow portion.

Further, the cross-sectional area ratio of this hollow portion is 30 to 5
It is possible in the range of 0%.

Further, the outer diameter of the hollow monofilament yarn used in each example was 0.3 mm, but the outer diameter was 0.1.
It is possible in the range of mm to 0.5 mm.

Table 1 shows the characteristics of the filter cloth (10) described in the first to fifth embodiments and the filter cloth using the nylon solid monofilament yarn prepared as a comparative example for the warp and the weft. .

For the purpose of evaluating the performance of the filter cloth (10) according to the present invention as a filtering material, a filtering test was carried out on the first settling sludge of the sewage treatment plant which was subjected to the conditions shown in Tables 2 and 3. did.

[0026]

[Table 2]

[0027]

[Table 3]

The results of the filtration experiment are collectively shown in Table 4.

[0029]

[Table 4]

It is understood from Table 4 that in both the second and fourth examples, solid content particles are trapped on the surface of the filter cloth (10) from the initial stage of the filtration, and the filtration layer is rapidly formed by the cake. It By comparing with the measured value according to Comparative Example 1, it is understood that a filtered solution having less turbidity is obtained, and the cake is smoothly consolidated and the water content is reduced.

Next, as a second performance evaluation experiment, a filter cloth (10) according to the present invention was attached to a vacuum dehydrator for collecting dredges used in a cooking process of kraft pulp for corrugated board liner, and Comparative Example 2, A filtration experiment was performed on the green liquor slurry collected from the dressings recovery step while comparing with 3. The experimental conditions are shown in Table 5 and the experimental results are shown in Table 6.
Shown in

[0032]

[Table 5]

[0033]

[Table 6]

Table 7 shows the characteristics of the filter cloths used as Comparative Examples 2 and 3 in the second performance evaluation experiment.

[0035]

[Table 7]

From Table 6, it is found that when the filter cloths shown in the first and fourth examples are used, the same degree of filter clarification as the coarse filter cloth made of multifilament used as Comparative Example 3 can be obtained. did. In addition, the peelability of the cake and the performance of preventing clogging were maintained at good levels. On the other hand, in the filter cloth shown in Comparative Example 2, the clarity of the filtrate was low, and in the filter cloth shown in Comparative Example 3, the peelability of the cake was poor, so that neither of them could be adopted.

Finally, as a third performance evaluation experiment, a filter cloth (10) for a vacuum type horizontal belt filter used in a phosphoric acid production process was listed as a third example and a comparative example shown in Table 9. Table 8 while comparing with 4
A filtration experiment was performed according to the conditions shown in. Table 10 shows the results of the filtration experiment.

[0038]

[Table 8]

[0039]

[Table 9]

[0040]

[Table 10] In the filter cloth (10) shown in the third embodiment, although the peelability of the cake is not much different from that of Comparative Example 4, the conditions of calendering to be carried out for the purpose of smoothing the surface and adjusting the air permeability are shown in Comparative Example 4. Compared with the fact that the filter cloth (10) can be set much looser and the filter cloth (10) can be easily densified, it greatly contributes to a reduction in manufacturing cost.

[0041]

As described above, according to the present invention, since hollow monofilament yarns are used as the warp yarns and / or weft yarns of the filter cloth, the flexibility of the hollow monofilament yarns can narrow the voids at the entanglement points of the warp yarns and the weft yarns. The capturing performance of fine particles can be improved. In addition, calendering for the purpose of improving the capturing performance of fine particles is not always necessary, or it becomes possible to loosen the temperature conditions of calendering. It is possible to eliminate adverse effects such as decrease in mechanical strength, shortening of service life, and increase of maintenance man-hours.

A filter cloth containing a hollow monofilament is easy to be calendered due to its flexibility, and the hollow monofilament yarn is easily flattened even under normal processing conditions, so that the surface of the filter cloth is smoothed and the woven structure is densified. When it is installed on a machine and used, the clearance for passing the filtrate is adjusted, and the peelability of the cake is improved,
A remarkable effect is exerted on improvement of productivity and extension of cleaning cycle. In addition, since it is easy to clean and has good initial state recovery, it is possible to improve productivity and reduce maintenance labor.

[Brief description of drawings]

FIG. 1A is a first filter cloth according to the present invention.
The perspective top view of an Example, (B) is the cross section figure.

2A is a perspective plan view of a second embodiment of the filter cloth, and FIG. 2B is a cross-sectional view thereof.

3A is a perspective plan view of a third embodiment of the filter cloth, and FIG. 3B is a cross sectional view thereof.

FIG. 4A is a perspective plan view of a fourth embodiment of the filter cloth, and FIG. 4B is a cross sectional view thereof.

FIG. 5A is a perspective plan view of a fifth embodiment of the filter cloth, and FIG. 5B is a perspective view illustrating an arrangement order of wefts.

[Explanation of symbols]

 1 Warp 2 Weft 3 Entangling point of warp and weft 3'Gap size between warps or between wefts 4 Gap between warps 5 Weft 6 Warp 7 Weft 10 Filter cloth

Claims (7)

[Claims] 1. A filter cloth obtained by weaving hollow monofilament yarns as warp yarns and / or weft yarns. 2. A filter cloth obtained by weaving warp yarns and / or weft yarns using aligned yarns of hollow monofilament yarns and solid monofilament yarns. 3. A filter cloth obtained by calendering the filter cloth according to claim 1 or 2. 4. The filter cloth according to claim 1, wherein the warp yarn and the weft yarn of the hollow monofilament yarn are made of any one material selected from nylon, polyester and polypropylene. 5. The hollow monofilament yarn warp yarn is constituted by one of arbitrary two materials selected from nylon, polyester and polypropylene, and the hollow monofilament yarn weft yarn is constituted by the other. Filter cloth described in. 6. The filter cloth according to claim 1, wherein the hollow monofilament yarn has a hollow portion having a cross-sectional area ratio of 30% to 50%. 7. The outer diameter of the hollow monofilament yarn is set in a range of 0.1 mm to 0.5 mm.
Or the filter cloth according to item 6.