JP2014151299A - Filter material for filter and air filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter which can solve a safety problem and is low in cost.SOLUTION: A filter material is formed of two or more layers. At least one layer is a sheet containing glass fiber. The sheet containing the glass fiber contains glass short fiber, organic short fiber, and a binder. The organic short fiber contains at least organic short fiber of 1-20 μm. The sheet contains the organic short fiber of 1-20 μm in diameter of at least 25% or more to the mass of the glass short fiber. The other layer contains a sheet of a meltblown unwoven fabric which is subjected to electret processing.

Description

  The present invention relates to a filter medium which can be used for general industrial use, air conditioning use, air purifier use, cleaning raising use, air conditioner use, in-vehicle use and the like, and particularly excellent in forming a three-dimensional shape such as a pleated type.

  Air conditioners and air purifiers used in buildings, factories, automobiles, general homes, etc. are used as air filters using filter media stored in a frame. Such a filter increases the filtration area by applying a mountain-like process called pleating process in order to put more filter medium in a limited size. These pleated filter media are maintained in shape using a separator or the like, a gap between the pleats is secured, and a frame is attached to be used as a filter.

Filter media used in these filters are often used in which a plurality of sheets having different densities are laminated in order to maintain the strength as a filter and to achieve high collection and low pressure loss. The laminate is composed of an aggregate layer for maintaining the strength as a filter and a collection layer for collecting particles. In particular, the aggregate layer is required to have high strength and low pressure loss.
For example, according to Patent Document 1 and Patent Document 2, a filter in which a glass fiber sheet is used as an aggregate and a melt blown nonwoven fabric is superimposed on the glass fiber sheet is disclosed. With such a filter, it is possible to suppress the pressure loss while increasing the strength. However, when the filter is pleated, the glass fiber is easily broken, so that the broken glass fiber is easily scattered or fluffed from the filter medium. There is a problem.
On the other hand, according to Patent Document 3, it is possible to prevent the glass fiber from scattering and fluffing by providing the nonwoven fabric on both sides of the glass fiber sheet, but the pressure loss increases because it is necessary to provide a nonwoven fabric layer on both sides. There was a problem that it became easy to do.
In addition, there is a filter using organic fibers for the aggregate, but there is a problem that the cost becomes higher as compared with the case where glass fibers are used to obtain the same strength as the glass fiber sheet.

JP-A-6-198108 JP-A-6-205915 Japanese Patent Laid-Open No. 2002-18216

  An object of the present invention is to provide a filter medium for a filter with less fuzz even when pleated.

In order to achieve the above object, the present invention has the following configuration.
(1) A filter medium including two or more sheets,
At least the first sheet includes short glass fibers, organic short fibers, and a binder resin, and the organic short fibers include fibers having a fiber diameter of at least 1 to 20 μm, and the 1 to 20 μm organic short fibers are short glass. At least 25% by weight with respect to the fiber,
A filter medium for a filter, wherein the second sheet is an electret-woven non-woven sheet;
(2) The organic short fiber having a fiber diameter of 1 to 20 μm in the first sheet is 100% by mass or less with respect to the glass short fiber, and the mass (A) of the whole organic fiber in the first sheet and glass The filter medium, wherein the fiber mass (B) ratio (A / B) is 25% to 400%,
(3) An air filter obtained by pleating one of the filter media.

  According to the present invention, there are provided a filter medium and an air filter for a filter with less fuzz even when pleated.

The filter medium of the present invention is a filter medium composed of at least two layers of sheets, preferably a non-woven sheet. In particular, in air filter applications used in home air purifiers and air conditioning equipment such as buildings, factories, and automobiles, the pressure loss is small in order not to impair the air permeability, and it has sufficient strength against wind pressure. In addition, when processed into a shape such as pleats, it is necessary to have rigidity that can maintain the shape and suppress an increase in pressure loss due to shape change, and excellent workability when forming into a shape such as pleats. And high collection efficiency is required. Therefore, in the present invention, in order to achieve strength and high collection, it is a laminated filter medium composed of two or more layers, at least the first sheet is a sheet containing glass fibers for maintaining strength, and the second sheet is high. It consists of a sheet of meltblown nonwoven fabric that has been electret processed to achieve collection. Furthermore, another layer can be included for further functionalization. In addition, it is preferable to arrange | position the sheet | seat containing glass fiber to an upstream, and the sheet | seat of a melt blown nonwoven fabric to a downstream from the problem of filter media lifetime.
The first sheet contains short glass fibers, organic short fibers, and a binder, and the fiber diameter of the organic short fibers needs to include at least 1 to 20 μm. If only the organic short fibers have a small fiber diameter, the pressure loss as a filter medium increases. If only the large organic fibers are large, there is a problem that the glass fibers tend to jump out from the gaps between the organic fibers during pleating. In particular, in order to achieve both pressure loss, glass fiber scattering, and fluff prevention, it is preferable to include many fibers having a fiber diameter of 10 to 20 μm, for example, 30% by mass or more in organic short fibers. From the viewpoint of an increase in pressure loss, organic short fibers having a fiber diameter of more than 20 and up to 50 μm may be included. Further, from the viewpoint of preventing the glass fiber from scattering and fluffing, the length average fiber length of the organic short fibers is preferably 5 mm or more. On the other hand, the average length is preferably 30 mm or less.
The organic short fibers are not particularly limited, and polyester fibers, vinylon fibers, and the like can be used.
The organic short fiber having a fiber diameter of 1 to 20 μm needs to be at least 25% or more with respect to the mass of the short glass fiber, and 30% or more is particularly preferable for preventing the glass fiber from scattering and fluffing. When there are few organic short fibers with respect to a glass fiber, the confounding property of an organic fiber and a glass fiber will worsen, and it exists in the tendency for scattering of a glass fiber and a fuzz to increase by the above-mentioned pleating process. On the contrary, if the amount is too large, the pressure loss tends to increase. Therefore, the upper portion is preferably 100% or less.
The ratio (A / B) of the total organic fiber mass (A) and the glass fiber mass (B) in the sheet containing glass fibers is preferably 25% to 400%. When the mass ratio (A / B) is large, the blending amount of the glass fiber is small, and usually it is expensive. The length average fiber length of the entire organic short fiber is preferably 5 mm or more, and preferably 30 mm or less, as in the case of 1 to 20 μm.
Although the fiber diameter of the short glass fiber is not particularly limited, it is preferably 1 μm or more because the pressure loss as a filter medium increases if it is small like the organic fiber, and the rigidity of the glass fiber increases if the diameter is large. Then, the glass fiber breaks the organic fiber during the pleating process, and the broken glass fiber pops out to reduce the scattering prevention effect. In addition, when the fiber length is short, the number of tangled points with one short glass fiber with the organic short fiber is reduced, and the glass fiber is likely to be scattered from the sheet. Therefore, the length average fiber length is 10 mm or more. Is preferable, and it is preferable that it is 30 mm or less. Moreover, it is preferable that a glass short fiber is 20 to 50% with respect to sheet | seat mass. If it is less, the amount of short glass fibers will be reduced and the effect of cost reduction will be lessened. If it is more, the effect of preventing scattering of organic short fibers will be lessened.

  The first sheet includes a binder resin. The binder resin has a function of bonding fibers and imparting strength to the sheet. The binder is not particularly limited, and polyvinyl alcohol resin, vinyl acetate resin, acrylic resin, urethane resin and the like can be used. In particular, it is preferable to use a polyvinyl alcohol resin or an acrylic resin because there is little off-flavor. Moreover, it is preferable that a binder is 10-40 mass% in a 1st sheet | seat. When the amount is small, the strength of the sheet tends to decrease, and when the amount is large, the pressure loss as a filter tends to increase.

  In addition to the short glass fiber, the organic short fiber, and the binder resin, the first sheet can be mixed with pulp and the like. In addition, pigments, dyes, colorants, water repellents, water absorbents, flame retardants, stabilizers, antioxidants, ultraviolet absorbers, inorganic particles such as metal particles, crystal nucleating agents, lubricants, plasticizers, perfumes, A deodorizing agent, an antibacterial agent, an antifungal agent, an antiviral agent, an antiallergen agent, a repellent, a gas adsorbent, a gas adsorbing porous material, and the like can be added.

The first sheet is retained strength To impart low pressure loss, as the basis weight of preferably 10 to 100 g / ^{m 2,} more preferably from 20 to 70 g / ^{m 2.} For the same reason, the thickness is preferably 0.05 to 0.5 mm, more preferably 0.15 to 0.4 mm.

  The method for producing the first sheet is not particularly limited and can be arbitrarily selected from known methods. However, the paper making method is preferable from the viewpoint of uniformly mixing the glass short fibers and the organic short fibers.

  In order to achieve high collection efficiency, the filter medium of the present invention includes a non-woven fabric layer as the second sheet. The second sheet is preferably a melt blown nonwoven fabric. In order to achieve a higher collection efficiency, polyolefin-based materials, particularly preferably polypropylene, is preferably used. And electret processing is done.

The electret processing method is not particularly limited, and can be arbitrarily selected from a charging method such as a corona discharge method, a pure water suction method, and a friction charging method for the nonwoven fabric sheet.
Moreover, the fiber used for the electret nonwoven fabric in this invention may contain the additive for improving the charging effect by electret processing. Various additives can be used as such additives, and hindered amine and triazine additives are more preferable because they can easily maintain static electricity.

Since the second sheet has both high collection performance and low pressure loss, the basis weight is preferably 10 to 50 g / m ² , more preferably 15 to 40 g / m ² . For the same reason, the thickness is preferably 0.05 to 0.4 mm.

  Two sheets are laminated. It is possible to arbitrarily select a sheet in which two sheets are simply stacked or a sheet in which sheets are bonded via an adhesive such as a heat fusion resin or a moisture curable resin. Among them, the method of bonding sheets with an adhesive is preferable because the performance of the electret nonwoven fabric before lamination is easily maintained and the sheets are not easily peeled off during pleating. When using heat-sealing resin, one sheet can be sprayed with powder adhesive and heated in the furnace, and then laminated with the other sheet, and one sheet with powder adhesive. It is possible to scatter and sandwich the other sheet with a heating roll and stack them. When using a moisture curable resin, an adhesive is applied to one sheet, and the other sheet is laminated and adhered.

When the filter medium is used as an air filter, the filter medium may be used as it is. However, in order to put more filter medium in a limited size, it is preferable to increase the sheet area by applying a mountain-like pleating process.
Examples of the pleating method include a reciprocating method and a rotary method. Further, in order to maintain the pleated shape, it is preferable to perform a separator process for inserting a separator such as a comb or a bead for maintaining a gap between the peaks, and it is preferable to perform a process by bead bonding from the viewpoint of production efficiency. Bead application may be either continuous or intermittent.
Moreover, it becomes possible to finish thin filter medium thickness by using glass fiber for a 1st sheet | seat. Normally, the smaller the gap between the mountains, the worse the wind and the higher the pressure loss of the pleated filter, but it becomes possible to widen the gap even at the same pitch by thinning the filter medium. And the pressure loss can be reduced.
The filter unit is manufactured by pasting a frame material coated with an adhesive around the pleated filter medium. In addition, a sheet with functional particles such as fungicides, anti-allergens, and gas-adsorbing porous materials attached or sandwiched between upstream and downstream of the pleated filter medium is attached to the frame material together with the pleated filter medium and fixed. Also good.
As the frame material, a metal frame, a nonwoven fabric frame, a paper frame or the like can be used, and any shape may be used. In addition, an adhesive tape, a urethane adhesive, a hot melt adhesive, or the like can be used for adhesion between the frame material and the pleated filter medium, but a hot melt adhesive is preferable from the viewpoint of workability and adhesiveness.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the evaluation method of each characteristic of the filter medium in a present Example is described below.
<Thickness>
The thickness of 10 locations was determined with a measurement sample area of 1 m ² using SM114 manufactured by Teclock Co., Ltd., and the arithmetic average value was used.
<Unit weight>
The sample is allowed to stand at 24 ° C. and 60% RH for 8 hours or longer to obtain the mass of the sample to be evaluated, and the mass per 1 m ² is corrected from the area to obtain the basis weight of each sample to be evaluated. The minimum area for measurement was 0.01 m ² or more.
<Pressure loss>
Two plate-shaped flanges that open to the size of the filter unit are set in the measurement device in advance, and the filter unit that is the object to be measured is set between the two flanges. The pressure was measured with a digital manometer (MA2-04P manufactured by MODUS) when the air was passed at a treatment air volume of 5.1 m ³ / min.

<Fuzzing>
Observe the apex (length 20mm) of the peak after pleating with a microscope. If the fiber length is not 2mm or more, ◎ 2mm or more is 1 or less. ○ 2mm or more The case where the number of protrusions was 2 or more was marked as x.

<Example 1>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . As composition, glass fiber (fiber diameter 15 μm, fiber length 20 mm) 30 mass%, polyester fiber ((1) fiber diameter 15 μm, fiber length 10 mm) 9 mass%, glass fiber (2) fiber diameter 25 μm, fiber length 10 mm) 10 Mass%, glass fiber (3) fiber diameter 40 μm, fiber length 10 mm) 11 mass%), pulp (10 mass%), binder resin (styrene acrylic polymer (glass transition temperature Tg 30 ° C., film-forming temperature 45 ° C.) 30 It adjusted so that it might become mass%.

(Second sheet)
A nonwoven fabric having a basis weight of 25 g / m ² was prepared from a polypropylene added with 1% by mass of “Kimasorb” (registered trademark) 944 (manufactured by Ciba Geigy Japan), which is a triazine compound, by a melt blow method. Furthermore, the obtained nonwoven fabric was electret-processed by the corona discharge method, and the electret nonwoven fabric was produced.

(Laminated filter media)
A moisture curable urethane resin was sprayed on the ^two sheets at 5 g / m ² to bond the seeds together to obtain a filter medium having a basis weight of 65 g / m ² .

(Pleats, beads, framed)
The filter medium is 235mm wide, 35mm high, and pleated at a pitch of 3.2mm. The non-woven frame is coated with a hot melt adhesive after cutting the pleated crest with 120 ridges as one filter unit. The four sides were sealed using a to prepare a filter. The obtained performance is shown in Table 1.

<Example 2>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . As a constitution, glass fiber (fiber diameter 15 μm, fiber length 20 mm) 30 mass%, polyester fiber (fiber diameter 15 μm, fiber length 10 mm) 30 mass%, pulp 10 mass%, binder (styrene acrylic polymer (glass transition temperature Tg30). C., film forming temperature 45.degree. C.) and 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A laminated filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

<Example 3>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . Composition is glass fiber (fiber diameter 15 μm, fiber length 20 mm) 30% by mass, polyester fiber ((1) fiber diameter 15 μm, fiber length 10 mm 8% by mass, glass fiber (2) fiber diameter 25 μm, fiber length 10 mm. 10% by mass, glass fiber (3) fiber diameter of 40 μm, fiber length of 10 mm, 12% by mass), pulp (10% by mass), binder (styrene acrylic polymer (glass transition temperature Tg 30 ° C., film forming temperature) 45 ° C.) 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

<Example 4>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . The composition is glass fiber (fiber diameter 15 μm, fiber length 20 mm, 47 mass%), polyester fiber (fiber diameter 15 μm, fiber length 10 mm, 13 mass%), pulp (10 mass%), binder (styrene acrylic) It was adjusted to be a polymer (glass transition temperature Tg 30 ° C., film-forming temperature 45 ° C. 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A laminated filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

<Comparative Example 1>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . As a constitution, glass fiber (fiber diameter 15 μm, fiber length 20 mm is 30% by mass), polyester fiber ((1) fiber diameter 25 μm, fiber length 10 mm is 12% by mass, (2) fiber diameter 40 μm, fiber length It was adjusted so as to be 10 mm (18% by mass), pulp (10% by mass), and binder (styrene acrylic polymer (glass transition temperature Tg 30 ° C., film forming temperature 45 ° C.) 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A laminated filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

<Comparative example 2>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . As a constitution, glass fiber (fiber diameter 15 μm, fiber length 20 mm is 30% by mass), polyester fiber ((1) fiber diameter 15 μm, fiber length 10 mm is 5% by mass, (2) fiber diameter 25 μm, fiber length 12% by weight for 10 mm, (3) fiber diameter 40 μm, 13% by weight for fiber length 10 mm), pulp (10% by weight), binder (styrene acrylic polymer (glass transition temperature Tg 30 ° C., film forming temperature) 45 ° C.) 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A laminated filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

<Comparative Example 3>
(First sheet)
After producing a fiber aggregate by an inclined wire-type wet papermaking method, the fiber aggregate was impregnated in a binder and dried and heat-treated to produce a sheet having a basis weight of 35 g / m ² . Consists of glass fiber (fiber diameter 15 μm, fiber length 20 mm, 50 mass%), polyester fiber (fiber diameter 15 μm, fiber length 10 mm, 10 mass%), pulp (10 mass%), binder (styrene acrylic) It was adjusted to be a polymer (glass transition temperature Tg 30 ° C., film-forming temperature 45 ° C. 30% by mass).

(Second sheet)
The same nonwoven fabric as in Example 1 was used.

(Laminated filter media)
A laminated filter medium having a basis weight of 65 g / m ² was obtained by the same laminating method as in Example 1.

(Pleats, beads, framed)
In the same manner as in Example 1, pleats, beads, and frame processing were performed to produce a filter. The obtained performance is shown in Table 1.

  Comparing the example and the comparative example, it can be seen that those within the scope of the present invention can suppress fuzz caused by pleating without significantly deteriorating the pressure loss.

  The filter medium of the present invention can be used for air filters used in home air purifiers and air conditioning equipment for buildings, factories, and vehicles.

Claims (3)

A filter medium comprising two or more sheets,
At least the first sheet includes glass short fibers, organic short fibers, and a binder resin, and the organic short fibers include fibers having a fiber diameter of at least 1 to 20 μm, and the organic short fibers having a fiber diameter of 1 to 20 μm. Is at least 25% by weight with respect to short glass fibers,
A filter medium for a filter, wherein the second sheet is a non-woven sheet subjected to electret processing.   The organic short fiber having a fiber diameter of 1 to 20 μm in the first sheet is 100% by mass or less based on the short glass fiber, and the mass (A) of the whole organic fiber in the first sheet and the mass of the glass fiber. The filter medium according to claim 1, wherein the ratio (A / B) of (B) is 25% to 400%.   An air filter obtained by pleating the filter medium according to claim 1.