JP3295132B2 - Filter media for dust collection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a front surface filtration filter medium Ru used to clean the high dust (dust) density pneumatic.

[0002]

2. Description of the Related Art Filter media for purifying air containing dust include:
There are filter media for internal filtration used in air conditioners and the like, and filter media for surface filtration used in dust collectors and vacuum cleaners, and both have different filtration principles. Internal filtration is used to purify air with relatively low dust concentration. The dust-containing airflow passes through the relatively coarse filter media as it is, and when the airflow passes through the filter media, the dust is collected inside the filter media. Is what you do. On the other hand, surface filtration is used for cleaning air having a relatively high dust concentration, and uses a filter medium having relatively fine eyes. That is, dust is collected on the surface of the filter medium to form a dust layer on the surface of the filter medium, and the dust layer successively collects dust. When the dust layer has a certain thickness, the dust layer is removed from the surface of the filter medium. The operation of removing and again forming a dust layer on the surface of the filter medium is repeated. Conventionally, as a filter material for surface filtration using a nonwoven fabric, a needle punch felt having a smooth surface by sintering, a needle punch felt having a smooth surface by pressurizing and heating (calender) treatment,
Further, there is known a needle punched felt in which a silicone resin or a Teflon resin is resin-processed on the surface to impart high releasability. However, in the case of these filter media, the pore size (opening diameter) increases, and dust easily enters the interior of the filter media. Therefore, it is difficult to remove the dust that has entered the interior of the filter media, and the life of the filter media is shortened. Also, if you try to reduce the pore size by these surface treatments,
It was difficult to control the pore size, and the ventilation resistance tended to be too large. Also, a filter medium in which a Teflon microporous membrane is laminated on the surface of a needle punch felt is known. This filter medium has a microporous membrane that prevents dust from entering the filter medium, performs efficient surface filtration, and excels in removing dust, but has the disadvantage that the thin film is easily damaged during the removal operation and the cost is high. was there.

[0003]

SUMMARY OF THE INVENTION The present inventor has prepared a high-density dense nonwoven fabric by hydroentangling a fibrous web made of fine fibers, and disposing the nonwoven fabric on the air inflow side of a filter medium forming a dust layer. Then, they found that a filter medium for surface filtration having a long life, high strength, and low cost was obtained. The present invention is based on these findings.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a water-entangled fibrous web composed of fibers having an average fineness of 3 deniers or less, and has an apparent density of 0.15 to 0.3 g / cm ^3.
The present invention relates to a dust-collecting filter medium for surface filtration , characterized by having a dense layer made of a nonwoven fabric on the air inflow side. According to a preferred embodiment of the present invention, the fibrous web contains split fibers or modified cross-section fibers (particularly in an amount of 25% by weight or more). Further, the filter material for dust collection for surface filtration according to another preferred embodiment of the present invention is formed into an electret by treating with a corona discharge.

The filter for dust collection of the present invention has a dense layer made of a nonwoven fabric at least on the air inflow side. This non-woven fabric
By using fine fibers having an average fineness of 3 denier or less as the web constituent fibers, the pore size is reduced, and the web is entangled at a high density by water entanglement, and further, the surface on the side subjected to water flow is provided with smoothness. be able to. These points indicate that it is difficult to entangle fine fibers at a high density in the needle punching process used in conventional nonwoven fabric filter media, and it was not easy to reduce the pore size. This is an excellent point of the present invention as compared with the necessity of smoothing treatment such as scabbing and heating and pressurizing. In addition, if the average fineness is larger than 3 denier, the pore size will increase,
The trapping effect is reduced, and the dust wiping property is deteriorated. The lower limit of the average fineness is not particularly limited. Furthermore,
The apparent density of the nonwoven fabric forming the dense layer is 0.15 g / cm
^{If it is} smaller than ³ , the effect of collecting the filter medium will decrease. On the other hand, if the apparent density is larger than 0.3 g / cm ³ , the airflow resistance becomes too large.

[0006] The constituent fibers of the nonwoven fabric constituting the dense layer of the filter medium of the present invention are not particularly limited.
Polypropylene, polyamide, rayon or the like can be used, but it is preferable to include at least a part of split fibers and / or fibers of irregular cross section. As the split fibers, for example, fibers made of a resin having two or more components having a fiber cross section as shown in FIG. 1 can be used. Before splitting, the split fiber 1 in FIG. 1 has, for example, a single yarn shape in which a polyamide fiber portion 2 and a polyester fiber portion 3 are combined (FIG. 1A), but is subjected to mechanical shock or the like. Easily divided into a polyamide fiber portion 2 (FIG. 1 (b)) and a polyester fiber portion 3 (FIG. 1 (c)),
Since each of the fiber portions 2 and 3 becomes a thinner yarn than the yarn before splitting and forms a nonwoven fabric, the denseness is improved and the surface area is increased. Suitable combinations of resins include polyamide-polyester, polyamide-polyethylene terephthalate, polypropylene-polyester, and polypropylene-polyethylene. Also, many cross-sectional shapes other than those shown in FIG. 1 are known, and any of them can be used. As split fibers,
Fibers that can be split by mechanical impact or by extracting one component can be used. In particular, it is preferable to use a fiber that is split by mechanical impact at the time of water entanglement, because the splitting and entanglement of the fiber can be performed simultaneously. In addition, in this specification, the average fineness of the split fiber is a numerical value before splitting.

As the irregular cross-section fiber (fiber having a non-circular cross section), fibers having various cross-sections can be arbitrarily used. For example, rayon-based fibers having a fiber cross-section as shown in FIG. 2 can be used. it can. By using these modified cross-section fibers, the surface area is increased. When the web is usually made of fibers, it is preferable to use thin fibers. When using split fibers and / or deformed fibers,
It is preferred that by containing them in an amount of 25% by weight or more, the compactness is improved and the surface filtration effect is increased.
The fibers constituting the filter material for dust collection, including the dense layer, include heat-resistant fibers such as aromatic polyamide fibers, polyphenylene sulfide (PPS) fibers, and polyimide fibers. The dust filter medium can be made heat-resistant.

The filter material for dust collection of the present invention may be a single layer or a multilayer, but the surface layer on the air inflow side must be the dense layer described above. The thickness of the dense layer is not particularly limited. The other layers are not particularly limited, but those having a lower density than the dense layer are preferable in consideration of the ventilation resistance of the entire filter for dust collection. Further, a reinforcing material such as a woven fabric, a mesh, or a filament may be laminated for reinforcement. In this case, it is desirable to use a reinforcing material having a tensile strength of 10 kg / 5 cm width or more. The water entanglement of the present invention has a water pressure of 5
It can be performed under the conditions of 0 to 200 kg / cm ² . Furthermore,
In order to increase the tensile strength of the filter material for dust collection, bonding with a thermoadhesive fiber or an adhesive may be used as the fiber bonding means in addition to the hydroentanglement. In particular, it is preferable to heat and press the entire surface or a part of the filter medium because not only the strength of the filter medium can be improved, but also the surface resistance and the surface smoothness can be increased.
In the filter for dust collection of the present invention, it is preferable that at least the dense layer is electretized to be in a charged state, and the dust collection efficiency is improved by utilizing static electricity. The electretization can be performed by, for example, corona discharge treatment with an electric field strength of 4 kV / cm or more.

[0009]

EXAMPLES The present invention will be described below in more detail with reference to examples, but these examples do not limit the scope of the present invention. In the following examples, the dust collection efficiency and the initial pressure loss are values measured by passing an airflow containing atmospheric dust having an average particle size of 0.5 μm at a wind speed of 5 cm / sec. Example 1: Filtered fiber non-woven fabric filter material A fiber web having a basis weight of 150 g / m ² composed of divided fibers (denier: 2 denier; fiber length: 51 mm) having a combination of a polyamide-polyester resin component having a fiber cross section shown in FIG. Under the condition of a water pressure of 100 kg / cm ^2, the fibers are entangled to split the split fibers (see FIGS. 1 (b) and (c)), and the fibers are entangled to have a thickness of 0.7 mm and an apparent density of 0. A filter material for dust collection of 0.21 g / cm ³ was obtained. In the dust collecting effect is 45% of the filter medium, the initial pressure loss was 6mmH ₂ O.

Example 2: Non-woven fabric of modified fiber and ordinary fiber
Filtering material : 180% / m ² basis weight composed of 50% irregular rayon fiber (1.5 denier fineness; fiber length 51 mm) having a fiber cross section of FIG. 2 and 50% polyester fiber (1.5 denier fineness; 51 mm fiber length) Water pressure of 100 on fiber web
Water entanglement was performed under the condition of kg / cm ² to obtain a filter material for dust collection having a thickness of 1.1 mm and an apparent density of 0.16 g / cm ³ . This filter medium has a dust collection efficiency of 46% and an initial pressure loss of 1.4 mm.
Was H ₂ O.

Comparative Example 1: Needle punch / non-woven fabric
Cloth filter media polyester fiber (denier 1.5 denier; fiber length 51m)
m), a fiber web having a basis weight of 500 g / m ² was subjected to needle punching under the condition of a needle density of 500 needles / cm ² to obtain a filter medium for dust collection having a thickness of 2.0 mm and an apparent density of 0.25 g / cm ^3. Obtained. The dust collection efficiency of this filter medium was 30%, and the initial pressure loss was 3.0 mmH ₂ O.

Comparative Example 2: Hydro-entangled nonwoven of large fineness ordinary fiber
Cloth filter media polyester fibers; a of basis weight 150 g / m ² consisting of (fineness 4 deniers fiber length 51 mm) fiber web, pressure 100
Water entanglement was performed under the condition of kg / cm ² to obtain a filter material for dust collection having a thickness of 0.9 mm and an apparent density of 0.17 g / cm ³ . This filter medium has a dust collection efficiency of 20% and an initial pressure loss of 1.5 mm.
Was H ₂ O.

Example 3: Nonwoven fabric of split fiber and ordinary fiber
Filter media : 30% of split fibers (fineness: 2 denier; fiber length: 51 mm) having a combination of the polyamide-polyester resin components used in Example 1 and 70% of polyester fibers (fineness: 1.5 denier; fiber length: 51 mm) Net weight 150g /
A water entanglement is applied to the fiber web of m ² under the condition of a water pressure of 100 kg / cm ² to split the split fibers and entangle the fibers to obtain a 0.8 mm thick, 0.19 g / cm ³ apparent density. A filter material for dust collection was obtained. The dust collection efficiency of this filter medium is 38%,
Initial pressure loss was 4.5mmH ₂ O.

Example 4: Non-woven fabric of modified fiber and ordinary fiber
Filter media Rayon fiber with irregular cross section used in Example 2 (fineness 1.
100 kg of water pressure is applied to a fiber web having a basis weight of 180 g / m ² , which is composed of 30% of 5 denier; fiber length 51 mm) and 70% of polyester fiber (fineness 1.5 denier; fiber length 51 mm).
/ Cm ² to obtain a filter medium for dust collection having a thickness of 0.12 mm and an apparent density of 0.15 g / cm ³ . This filter medium has a dust collection efficiency of 40% and an initial pressure loss of 0.8 mm.
Was H ₂ O.

Example 5: Electretized filter medium polypropylene fiber (denier 2 denier; fiber length 51 mm)
A fibrous web with a basis weight of 120 g / m ² consisting of
Water entanglement under the condition of 0 kg / cm ² , thickness 0.8 mm,
An apparent density of 0.15 g / cm ³ was obtained, and then a corona discharge treatment was performed at 5 KV / cm to obtain an electretized filter material for dust collection. The dust collection efficiency of this filter medium is 55%,
Initial pressure loss was 1.0mmH ₂ O.

Example 6: 30% of aromatic polyamide fiber (fineness: 2 denier; fiber length: 51 mm), 30% of polyimide fiber (fineness: 1.5 denier, fiber length: 51 mm) as a fiber layer on the air inlet side of the heat-resistant filter medium . And a fiber web having a basis weight of 60 g / m ² composed of 40% of polyphenylene sulfide fiber (fineness: 2 denier; fiber length: 51 mm) and aromatic polyamide fiber (fineness: 3 denier; fiber length: 51 mm) 60% as a fiber layer on the air outflow side. And a polyphenylene sulfide fiber (denier: 2 denier; fiber length: 51 mm), a fiber web having a basis weight of 100 g / m ² and a water entanglement under a water pressure of 150 kg / cm ² . 9mm, apparent density 0.17g / cm
^The filter material for dust collection of No. ³ was obtained. The dust collection efficiency of this filter medium is 45
%, The initial pressure loss was 0.8mmH ₂ O.

Example 7: Wet water entangled ordinary fiber non-woven fabric filter
Material polyester fiber (fineness 0.1 denier; fiber length 5 mm)
100 g / m ² of a fiber web made by wet papermaking, and then subjected to hydroentanglement under the condition of a water pressure of 100 kg / cm ² to obtain a filter material for dust collection having a thickness of 0.6 mm and an apparent density of 0.17 g / cm ^3. Obtained. In the dust collecting effect is 55% of the filter medium, the initial pressure loss was 16mmH ₂ O.

[0018]

The filter medium for dust collection according to the present invention has a long life and a large strength as a filter medium for surface filtration because a high-density dense nonwoven fabric layer made of fine fibers is arranged on the air inflow side. Cost is low. The filter medium of the present invention is useful, for example, as a filter medium for dust collectors and vacuum cleaners.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a split fiber that can be used in the present invention, where (a) is a cross-sectional view before splitting, (b) is a cross-sectional view of a polyamide fiber portion after splitting, and (c) is a cross-sectional view after splitting. FIG. 2 is a cross-sectional view of a polyester fiber portion.

FIG. 2 is a cross-sectional view of a modified fiber that can be used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Split fiber 2 ... Polyamide fiber part 3 ... Polyester fiber part

Claims (3)

(57) [Claims] An apparent density of 0.1 formed by hydroentanglement of a fiber web composed of fibers having an average fineness of 3 deniers or less.
A dust-collecting filter medium for surface filtration , comprising a dense layer made of a nonwoven fabric of 5 to 0.3 g / cm ^{3 on} the air inflow side. 2. The filter material for dust collection for surface filtration according to claim 1, wherein the fibrous web contains split fibers or modified fibers. 3. The filter medium for surface filtration according to claim 2, wherein the fibrous web contains at least 25% by weight of split fibers or irregular fibers.