WET NON-WOVEN FABRIC FOR FILTER, FILTER MEDIUM FOR FILTER, AND FILTER

Abstract

The wet non-woven fabric for a filter of the present invention comprises vinylon, polyester, and polyvinyl alcohol, the wet non-woven fabric comprises 10 to 20% by weight of the polyvinyl alcohol, and a surface, of the wet non-woven fabric, that is located on an upstream side of air flow has a surface roughness (SMD) of not larger than 2.7 m.

Claims

1. A wet non-woven fabric for a filter, wherein the wet non-woven fabric comprises vinylon, polyester, and polyvinyl alcohol, and a surface, of the wet non-woven fabric, that is located on an upstream side of air flow has a surface roughness (SMD) of not larger than 2.7 m.

2. The wet non-woven fabric far a filter according to claim 1, wherein the surface located on the upstream side of air flow has an average friction coefficient (MIU) of not larger than 0.15.

3. The wet non-woven fabric for a filter according to claim 1, the wet non-woven fabric comprises 10 to 20% by weight of the polyvinyl alcohol.

4. The wet non-woven fabric for a filter according to claim 1, the wet non-woven fabric comprises 0.001 to 0.1% by weight of a polyacrylic acid ester.

5. The wet non-woven fabric for a filter according to claim 1, the wet non-woven fabric comprises a fiber having a length of not longer than 30 mm.

6. A filter in which the wet non-woven fabric for a filter according to claim 1 is used.

7. A filter medium for a filter having a laminate structure in which a long-fiber non-woven fabric and the wet non-woven fabric for a filter according to claim 1 are stacked.

8. The filter medium for a filter according to claim 7, wherein the long-fiber non-woven fabric is a spunbonded non-woven fabric.

9. The filter medium for a filter according to claim 7, wherein an adsorbent is held between the long-fiber non-woven fabric and the wet non-woven fabric.

10. A filter in which the filter medium for a filter according to claim 7 is used.

Description

EXAMPLES

[0050] Hereinafter, the present invention will be more specifically described by means of examples. However, the present invention is not limited to the examples. First, a method for measuring physical properties of wet non-woven fabrics and filter mediums for filters used in examples and comparative examples will be described.

Surface Irregularity

[0051] Evaluation is conducted by using a friction tester (KES-SE) manufactured by KATO TECH CO., LTD. Each sample (non-woven fabric) fixed to a table is scanned with a contact piece while applying a load of 10 gf at a speed of 1 mm/s. Then, an average deviation from data of detected surface irregularities is regarded as the value of surface roughness (SMD).

Average Friction Coefficient

[0052] Evaluation is conducted by using the friction tester (KES-SE) manufactured by KATO TECH CO., LTD. Each sample fixed to the table is scanned with the contact piece while applying a load of 25 gf at a speed of 1 mm/s. Then, an average friction coefficient (MIU) is calculated based on the detection result.

Foreign Object Removal Performance

[0053] Each sample is cut into a size of 15 cm-square, JIS15-type powder dust is caused to fall on the sample at 5 m.sup.3/min, and the falling is stopped at the time when the air-flow resistance of the sample has increased by 50 Pa from a base value. Evaluation based on the amount of powder dust caught by the sample is made in terms of the weight. Then, the sample having a size of 15 cm-square is set on a jig perpendicularly to a table and caused to fall off from a height of 10 cm ten times. Lastly, the weight of the sample is measured, and the weight of powder dust having fallen off from the sample is obtained. If the weight of the powder dust having fallen off from the sample is 70% of the adhesion amount, the foreign object removal performance is determined to be good ().

Pressure Loss

[0054] Each filter medium is placed in a duct, and air is caused to flow through the filter medium at an air filtering speed of 50 cm/second. Then, a differential pressure gauge is read to obtain the difference in static pressure between the upstream side and the downstream side of the sample, whereby a pressure loss (Pa) is measured.

Peel Strength

[0055] The average peel strength between the long-fiber non-woven fabric and the wet non-woven fabric is measured. A test is performed at a tensile strength of 100 mm/minute on each test piece, the size of which is such that the width is 50 mm and the length is 200 mm.

Rigidity

[0056] A stiffness in a machine direction is measured according to Method A (Gurley method) of JIS L-1096.

Example 1

[0057] Vinylon fibers (17 dtex, average fiber length: 12 mm, average fiber diameter: 40 m), vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 26:31.25:5.25:11.25:11.25:15. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet. paper-making.

[0058] The undiluted liquid for wet paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet non-woven fabric for Example 1 having a weight per unit area of 40 g/m.sup.2 and a thickness of 0.3 mm.

[0059] Next, a mixed powder of which the weight ratio between a coconut husk activated carbon having an average particle diameter of 200 m and a polyester-based thermoplastic resin having an average particle diameter of 200 m was 1:0.5, was dispersed on a downstream side relative to the obtained wet non-woven fabric for Example 1 so as to obtain a weight per unit area of 90 g/m.sup.2. Furthermore, a polyester-based long-fiber non-woven fabric having a weight per unit area of 20 g/m.sup.2 was stacked on the dispersed mixed powder. The resultant stack was subjected to a heating process at 140 C. to be formed as a sheet, thereby producing a filter medium for a filter for Example 1.

Example 2

[0060] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 .dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 51:7.6:16.2:16.2:9. Furthermore, a polyacrylic acid ester was added while measurement was performed such that the proportion of the weight of the polyacrylic acid ester was 0.05% with respect to the weight of the fibers. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet paper-making.

[0061] The undiluted liquid for wet paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet non-woven fabric for Example 2 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0062] Next, a filter medium for a filter for Example 2 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Example 2 was used instead of the wet non-woven fabric for Example 1.

Example 3

[0063] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 45:7.6:16.2:16.2:15. Furthermore, a polyacrylic acid ester was added while measurement was performed such that the proportion of the weight of the polyacrylic acid ester was 0.05% with respect to the weight of the fibers. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet paper-making.

[0064] The undiluted liquid for wet. paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C. thereby obtaining a wet non-woven fabric for Example 3 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0065] Next, a filter medium for a filter far Example 3 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Example 3 was used instead of the wet non-woven fabric for Example 1.

Example 4

[0066] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 39:7.6:16.2:16.2:21. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid far wet paper-making.

[0067] The undiluted liquid for wet paper-making was subjected to paper making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet non-woven fabric for Example 4 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0068] Next, a filter medium for a filter for Example 4 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Example 4 was used instead of the wet non-woven fabric for Example 1.

Example 5

[0069] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 45:7.6:16.2:16.2:15. Furthermore, a polyacrylic acid ester was added while measurement was performed such that the proportion of the weight of the polyacrylic acid ester was 0.15% with respect to the weight of the fibers. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet paper-making.

[0070] The undiluted liquid for wet paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet non-woven fabric for Example 5 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0071] Next, a filter medium for a filter for Example 5 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Example 5 was used instead of the wet non-woven fabric for Example 1.

Comparative Example 1

[0072] Low-melting polyester fibers (22 dtex, average fiber length: 64 mm, average fiber diameter: 45 m), low-melting polyester fibers (4.4 dtex, average fiber length: 51 mm, average fiber diameter: 20 m), and regular polyester fibers (17 dtex, average fiber length: 51 mm, average fiber diameter: 40 m) were mixed together at a weight ratio of 5:3:2. Then, by thermal bonding the mixed fibers, and as a result, obtaining a thermally bonded non-woven fabric for Comparative Example 1 having a weight per unit area of 65 g/m.sup.2 and a thickness of 0.2 mm.

[0073] Next, a filter medium for a filter for Comparative Example 1 was produced in the same manner as for Example 1, except that the thermally bonded non-woven fabric for Comparative Example 1 was used instead of the wet non-woven fabric for Example 1.

Comparative Example 2

[0074] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 mm) were mixed together at a weight ratio of 51:7.6:16.2:16.2:9. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet paper-making.

[0075] The undiluted liquid for wet paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet, non-woven fabric for Comparative Example 2 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0076] Next, a filter medium for a filter for Comparative Example 2 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Comparative Example 2 was used instead at the wet non-woven fabric for Example 1.

Comparative Example 3

[0077] Vinylon fibers (7 dtex, average fiber length: 10 mm, average fiber diameter: 25 m), vinylon fibers (2.2 dtex, average fiber length: 6 mm, average fiber diameter: 15 m), polyester fibers (0.6 dtex, average fiber length: 5 mm, average fiber diameter: 8 m), polyester fibers (2.2 dtex, average fiber length: 5 mm, average fiber diameter: 15 m), and PVA fibers (1.1 dtex, average fiber length: 3 mm, average fiber diameter: 10 m) were mixed together at a weight ratio of 45:7.6:16.2:16.2:15. Furthermore, a polyacrylic acid ester was added while measurement was performed such that the proportion of the weight of the polyacrylic acid ester was 0.0009% with respect to the weight of the fibers. Then, the mixture was dispersed in water with a pulper, thereby preparing an undiluted liquid for wet paper-making.

[0078] The undiluted liquid for wet paper-making was subjected to paper-making by a short net type paper-making method, thereby making a wet web. Thereafter, the wet web was gently squeezed with a press roller and dried with a rotary drying drum at 140 C., thereby obtaining a wet non-woven fabric for Comparative Example 3 having a weight per unit area of 30 g/m.sup.2 and a thickness of 0.2 mm.

[0079] Next, a filter medium for a filter for Comparative Example 3 was produced in the same manner as for Example 1, except that the wet non-woven fabric for Comparative Example 3 was used instead of the wet non-woven fabric for Example 1.

[0080] Table 1 indicates the results of the evaluations regarding the wet non-woven fabrics and the thermally bonded non-woven fabric for the examples and the comparative examples.

TABLE-US-00001 TABLE 1 Example Example Example Example Example Comparative Comparative Comparative Item 1 2 3 4 5 Example 1 Example 2 Example 3 Wet non- Material Vinylon, Vinylon, Vinylon, Vinylon, Vinylon, Polyester Vinylon, Vinylon, woven Polyester, Polyester, Polyester, Polyester, Polyester, Polyester, Polyester, fabric PVA PVA PVA PVA PVA PVA PVA Production method Wet paper- Wet paper- Wet paper- Wet paper- Wet paper- Thermally Wet paper- Wet paper- making making making making making bonded making making PVA ratio (%) 15 9 15 21 15 9 15 Content ratio of Poly- 0.05 0.05 0.15 0.0009 acrylic acid ester (%) Weight per unit 30 30 30 30 30 65 30 30 area (g/m.sup.2) Surface Irregularity 2.4 2.5 1.5 2.3 2.5 4.3 4.1 3.1 Average Friction 0.1 0.13 0.04 0.1 0.14 0.31 0.25 Coefficient Air-flow resistance 5.5 6 6 9.0 8.8 5 4.5 5.6 (Pa), 30 cm/s Foreign Object Removal Performance x x x

[0081] From Table 1, it is found that the foreign object removal performance is excellent if a wet non-woven fabric of which a surface located on the upstream side of air flow ha a surface roughness (SMD) of not larger than 2.7 m is used. That is, a filter in which the wet non-woven fabric for a filter of the present invention is used, can be easily cleaned.

[0082] Next, Table 2 indicates the results of the evaluations regarding the filter mediums produced for the examples and the comparative examples. Measurement was performed on each of the filter mediums for Examples 1 to 5 and the filter mediums for Comparative Examples 2 and 3, with the wet non-woven fabric being located on the upstream side of air flow and with the long-fiber non-woven fabric being located on the downstream side of air flow Meanwhile, measurement was performed on the filter medium for Comparative Example 1, with the thermally bonded non-woven fabric being located on the upstream side of air flow and with the long-fiber non-woven fabric being located on the downstream side of air flow.

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 1 Example 2 Example 3 Wet non- Material Vinylon, Vinylon, Vinylon, Vinylon, Vinylon, Polyester Vinylon, Vinylon, woven fabric Polyester, Polyester, Polyester, Polyester, Polyester, Polyester, Polyester, PVA PVA PVA PVA PVA PVA PVA Production method Wet paper- Wet paper- Wet paper- Wet paper- Wet paper- Thermally Wet paper- Wet paper- making making making making making bonded making making Weight per unit area (g/m.sup.2) 30 30 30 30 30 65 30 30 Surface Irregularity 2.4 2.5 1.5 2.3 2.5 4.3 4.1 3.1 Average Friction Coefficient 0.1 0.13 0.04 0.1 0.14 0.31 0.25 Content ratio of 0.05 0.05 0.15 0.0009 Polyacrylic acid ester (%) Middle layer Particle size of 200 200 200 200 200 200 200 200 Granular activated carbon or Silica gel (m) Particle size of Granular 200 200 200 200 200 200 200 200 binder resin (m) Material of Granular EVA EVA EVA EVA EVA EVA EVA EVA binder resin Long-fiber Material Polyester Polyester Polyester Polyester Polyester Polyester Polyester Polyester non-woven Production method Spunbond Spunbond Spunbond Spunbond Spunbond Spunbond Spunbond Spunbond fabric Weight per unit area (g/m.sup.2) 20 20 20 20 20 20 20 2 Performance Pressure Loss (Pa) 38 36 40 39 39 41 39 40 of Filter Peel Strength (N) 3.7 3.5 3.3 3.6 3.9 2.7 3.1 3.6 mediums Rigidity (MD direction) (mg) 645 601 632 643 639 438 602 630 Foreigp Object Removal Performance x x x

[0083] From Table 2, it is found that, if a wet non-woven fabric of which the surface located on the most upstream side of air flow has a surface roughness (SMD) of not larger than 2.7 m is used, the filter medium is excellent in removal of a foreign object.

[0084] It should be understood that all of the embodiment and the examples described above are exemplary and not restrictive. Any embodiments and examples obtained by combining, as appropriate, configurations disclosed in the embodiment and the examples are also included in the present invention. That is, the technical scope of the present invention is valid within the scope of the claims and encompasses all changes, modifications, substitutions, and the like that are made within meanings and scopes equivalent to those described in CLAIMS.

Industrial Application

[0085] The non-woven fabric for a filter, the filter medium for a filter, and the filter of the present invention are excellent in removal of a foreign object at the time of cleaning, and can be effectively used for/as general filters for use in, for example, automobiles, air cleaners, air conditioners, copying machines, printers, multifunctional OA devices, toilet deodorizers, and the like.