Filter media and filters

Abstract

A filtering medium for a filter according to the present invention has a laminated structure in which a long fiber non-woven fabric and a substrate layer non-woven fabric are laminated, wherein the substrate layer non-woven fabric is arranged in an outermost layer of the filtering medium for a filter, and the average friction coefficient of a surface arranged in the outermost layer is 0.15 or more.

Description

[Technical Field]

[0001] This invention relates to filter media and filters. [Background technology]

[0002] In recent years, there has been a growing demand for high-performance and low-cost filter media in filters for air conditioning, automobiles, and other applications. As a result, much research has been conducted on filter media that can achieve both dust removal and deodorizing performance (see, for example, Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. "JP-A-11-5058" [Patent Document 2] Japanese Patent Publication No. "JP-A-3-98642" [Patent Document 3] Japanese Patent Publication No. 2001-218824 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Such filter media have the problem of the collected dust being re-scattered. Therefore, in view of the above problem, the present invention aims to provide a filter media and a filter that reduce the re-scattering of collected dust. [Means for solving the problem]

[0005] As a result of diligent research, the inventors of this invention have found that the above problems can be solved by the means described below, and have arrived at the present invention. That is, the present invention is as follows. A filter medium for a filter having a laminate structure in which a long fiber nonwoven fabric and a base layer nonwoven fabric are laminated, wherein the base layer nonwoven fabric is disposed on the outermost layer of the filter medium for a filter, and the average coefficient of friction of the outermost surface is 0.15 or more. (2) The base layer nonwoven fabric contains 0.1 g / m

[0007] or more to 1.5 g / m 2 or less of a thickener. The filter medium for a filter according to (1) above. (3) The base layer nonwoven fabric is a spunbond nonwoven fabric, a wet nonwoven fabric, or a thermal bond nonwoven fabric containing a polyester resin. The filter medium for a filter according to (1) or (2) above. (4) The long fiber nonwoven fabric is electretized. The filter medium for a filter according to any one of (1) to (3) above. (5) The long fiber nonwoven fabric is a melt blown nonwoven fabric. The filter medium for a filter according to any one of (1) to (4) above. (6) An adsorbent is sandwiched between the long fiber nonwoven fabric and the base layer nonwoven fabric. The filter medium for a filter according to any one of (1) to (5) above. (7) A filter using the filter medium for a filter according to any one of (1) to (6) above.

Effect of the Invention

[0008] In this specification, the average coefficient of friction refers to the value of MIU indicating the ease of sliding of the surface in the evaluation by a friction feeling tester (KES-SE) manufactured by Kato Tech. As the value of MIU increases, it indicates that the surface is difficult to slide. <{

[0009] In the filter medium of this embodiment, the base material layer nonwoven fabric is disposed on the outermost layer of the filter medium for the filter, and the average coefficient of friction of the outermost surface is 0.15 or more, so that the collected dust is likely to get caught and the dust can be retained, thus preventing the re-scattering of the dust. If the average coefficient of friction of the outermost surface is less than 0.15, the collected dust will re-scatter.

[0010] In the filter medium of this embodiment, as the material constituting the long fiber nonwoven fabric, polyolefin-based resins, polyester-based resins, polyamide-based resins, polyurethane-based resins, etc. can be used. If it is a polyolefin-based resin, since the rigidity is relatively high, the strength of the filter medium increases and the processing becomes easy when pleating is performed.

[0011] [[ID=I5]] In the filter medium of this embodiment, the fiber orientation of the long fiber nonwoven fabric is not particularly limited, and for example, it may be random, cross-shaped, or parallel.

[0012] The basis weight of the long fiber nonwoven fabric of this embodiment is preferably 5 to 100 g / m 2 and more preferably 10 to 80 g / m 2 If the basis weight is less than 5 g / m 2 the rigidity becomes weak. On the other hand, if it exceeds 100 g / m 2 not only does the pressure loss increase with the increase in the number of fibers, but the dust retention space between the fibers decreases and the dust retention amount decreases.

[0013] In this embodiment, the average fiber diameter of the constituent fibers of the long-fiber nonwoven fabric is preferably 1 to 100 μm, and more preferably 1 to 50 μm. The long-fiber nonwoven fabric is positioned downstream of the airflow during air purification. Therefore, as it is the inlet surface for the air to be treated, if the average fiber diameter of the constituent fibers is less than 1 μm, the gaps between the fibers become narrower, dust in the air accumulates on the nonwoven fabric, and the airflow resistance increases sharply. If the average fiber diameter of the constituent fibers is greater than 100 μm, and an adsorbent is sandwiched between the base layer nonwoven fabric, the adsorbent may pop out or fall off, especially during pleating.

[0014] Furthermore, the long-fiber nonwoven fabric may be subjected to electret processing. When processed, the filter's ability to remove submicron particles, including tobacco smoke particles, carbon particles, and sea salt particles, is increased, extending the filter's lifespan. Electret processing is not particularly limited and can be carried out by known methods such as corona discharge or water flow charging.

[0015] In this embodiment, the long-fiber nonwoven fabric is preferably a melt-blown nonwoven fabric from the viewpoint of collection efficiency and dust retention.

[0016] In the filter material of this embodiment, the materials constituting the base layer nonwoven fabric can be polyolefin resins, polyester resins, cellulose resins, polyamide resins, polyurethane resins, acrylic resins, polyvinyl alcohol resins, polycarbonate resins, and the like.

[0017] In the filter material of this embodiment, the fiber orientation of the base layer nonwoven fabric is not particularly limited and may be random, cross-shaped, or parallel.

[0018] In the filter material of this embodiment, the average fiber diameter of the constituent fibers of the base layer nonwoven fabric is preferably 1 to 100 μm, and more preferably 5 to 50 μm. If the average fiber diameter of the constituent fibers is smaller than 1 μm, the gaps between the fibers become narrower, dust from the air accumulates, and the airflow resistance increases sharply. If the average fiber diameter of the constituent fibers is larger than 100 μm, it becomes difficult to remove (capture) foreign matter.

[0019] In the filter medium of the present embodiment, the basis weight of the base material layer non-woven fabric is preferably 10 to 100 g / m 2 and more preferably 20 to 80 g / m 2 . If the basis weight is less than 10 g / m 2 , the texture will deteriorate. If the basis weight exceeds 100 g / m 2 , the thickness of the filter medium will increase, and when it is made into a pleated filter, the structural resistance will increase.

[0020] In the filter medium of the present embodiment, it is preferable that the base material layer non-woven fabric contains a thickener. By containing a thickener, the smoothness of the non-woven fabric surface can be adjusted. The thickener is not particularly limited as long as it is water-soluble and has a thickening effect. Examples thereof include sodium carboxymethyl cellulose, xanthan gum, carrageenan, cellulose, hydroxyethyl cellulose, and the like.

[0021] The filter medium of the present embodiment preferably has a thickness of 0.1 to 3.0 mm. If the thickness is less than 0.1 mm, the texture will deteriorate. If the thickness is greater than 3.0 mm, it will be too thick, and when it is made into a pleated filter, the structural resistance will increase, and as a result, the ventilation resistance of the entire filter will be too high, which causes practical problems.

[0022] In the filter medium of the present embodiment, an adsorbent may be sandwiched between the long fiber non-woven fabric and the base material layer non-woven fabric.

[0023] As the adsorbent of the filter medium of the present embodiment, in addition to inorganic substances such as activated carbon, silica gel, zeolite, and sepiolite, organic porous bodies typified by styrene-divinylbenzene cross-linked bodies can be used. In particular, activated carbon and silica gel are preferable because they have an extremely large specific surface area. The shape and size of the adsorbent may be those known to be used in filters.

[0024] When using activated carbon as an adsorbent, suitable types include those derived from coconut shells, wood, coal, and pitch. A higher number of internal pores, or macropores, as observed by surface observation, is preferable. A higher number of macropores allows for the opening of adsorption-capable pores during hot pressing, even if the binder coats the surface of the activated carbon when manufacturing a mixed powder or granular material consisting of activated carbon and a granular binder. Furthermore, a somewhat rough surface of the activated carbon reduces the fluidity of the molten binder resin, thus suppressing a decrease in adsorption performance.

[0025] In this embodiment, the filter material may be treated with chemicals to improve the adsorption performance of polar substances and aldehydes. Examples of chemicals used for this treatment include amine-based agents such as ethanolamine, polyethyleneimine, aniline, p-anisidine, sulfanilic acid, tetrahydro-1,4-oxazine, and hydrazide compounds, when the adsorbent is an aldehyde gas, nitrogen compounds such as NOx, sulfur compounds such as SOx, or acidic polar substances such as acetic acid. Tetrahydro-1,4-oxazine is preferred as the amine-based agent. It is relatively easy to obtain and readily soluble in water, making impregnation easy. In addition, sodium hydroxide, potassium hydroxide, guanidine carbonate, guanidine phosphate, aminoguanidine sulfate, 5,5-dimethylhydantoin, benzoguanamine, 2,2-iminodiethanol, 2,2,2-nitrotriethanol, ethanolamine hydrochloride, 2-aminoethanol, 2,2-iminodiethanol hydrochloride, p-aminobenzoic acid, sodium sulfanilate, L-arginine, methylamine hydrochloride, semicarbazide hydrochloride, hydrazine, hydroquinone, hydroxylamine sulfate, permanganate, potassium carbonate, potassium bicarbonate, etc. are also suitably used. When the adsorbent is a basic polar substance such as ammonia, methylamine, trimethylamine, or pyridine, for example, phosphoric acid, citric acid, malic acid, ascorbic acid, or tartaric acid are suitably used. Adsorbents treated with these chemicals may be used alone or mixed with untreated adsorbents.

[0026] Chemical treatment is carried out, for example, by supporting or impregnating the adsorbent with the chemical. In addition to directly treating the adsorbent with the chemical, it is also possible to impregnate the surface of the filter media using conventional coating methods, or to impregnate the entire filter media with the chemical. In this case, it is also possible to prepare an aqueous solution of the chemical mixed with a thickener such as sodium alginate or polyethylene oxide and then support or impregnate it with this solution. This method is effective for supporting or impregnating chemicals with low solubility in water and also helps to suppress the shedding of the chemical.

[0027] A binder can be used to fix the adsorbent to the long-fiber nonwoven fabric and / or the base layer nonwoven fabric. The binder is preferably made of a thermoplastic resin, and examples of thermoplastic resins include polyolefin resins, polyamide resins, polyester resins, and ethylene-acrylic copolymer resins. The components of the binder are not particularly limited, but polyolefin resins and polyester resins are preferred. This is because the interface between the long-fiber nonwoven fabric and / or the base layer nonwoven fabric and the binder is firmly bonded, resulting in high peel strength.

[0028] The thermoplastic resin used as the binder for the filter media in this embodiment is preferably in powder (granular) form with an average particle size of 100 to 400 μm. If the granular thermoplastic resin (granular binder) is less than 100 μm, adhesive forces due to van der Waals forces and electrostatic forces act between the adsorbent and the thermoplastic resin, preventing the thermoplastic resin from actively contacting the substrate layer, and thus insufficient peel strength can be obtained. On the other hand, if it exceeds 400 μm, the thickness of the filter media increases, increasing the structural resistance when used as a filter, which is undesirable in practical terms.

[0029] The binder used in the filter material of this embodiment is preferably used in an amount of 10 to 80% by weight relative to the adsorbent, and more preferably in an amount of 20 to 60% by weight. Within this range, a filter material with excellent adhesion to the base layer, pressure loss, and deodorizing performance can be obtained.

[0030] The thermoplastic resin used as the binder for the filter media in this embodiment is preferably in powder (granular) form with an average particle size of 100 to 400 μm. If the granular thermoplastic resin (granular binder) is less than 100 μm, adhesive forces due to van der Waals forces and electrostatic forces act between the granular adsorbent and the thermoplastic resin, preventing the thermoplastic resin from actively contacting the substrate layer, and thus insufficient peel strength can be obtained. On the other hand, if it exceeds 400 μm, the thickness of the filter media increases, increasing the structural resistance when used as a filter, which is undesirable in practical terms.

[0031] The granular binder used in the filter material of this embodiment is preferably used in an amount of 10 to 80% by weight relative to the granular adsorbent, and more preferably in an amount of 20 to 60% by weight. Within this range, a filter material with excellent adhesion to the base layer, pressure loss, and deodorizing performance can be obtained.

[0032] The filter material of this embodiment may include components with additional functions such as antibacterial agents, antifungal agents, antiviral agents, and flame retardants. These components may be kneaded into the fibers or nonwoven fabrics that make up the base layer, or they may be impregnated and supported during post-processing. For example, by including a flame retardant in the filter material, it is possible to manufacture a filter material that conforms to the flame retardancy standards specified in FMVSS.302 and the UL flame retardancy standards.

[0033] A filter of this embodiment using the filter material of this embodiment is also within the scope of the present invention. The filter of this embodiment may be subjected to, for example, pleating or mounting to a frame. Furthermore, the filter of this embodiment may be formed by combining the filter material of this embodiment with other materials. [Examples]

[0034] The present invention will be described in more detail below with reference to examples. The characteristics shown in the following examples and comparative examples were measured by the following methods. Note that the present invention is not limited to those described in the examples.

[0035] (Atmospheric dust efficiency) A filter material punched to a diameter of 72 mm is attached to an adapter with an effective airflow diameter of 50 mm, and the atmospheric dust efficiency is calculated using a light scattering particle counter under the following conditions. Particles evaluated: atmospheric dust particles Wind speed: 10cm / sec Particle count: Calculated using the light scattering counting method for 0.3 μm particles. Airborne dust efficiency (%) = {1 - (number of particles downstream of the sample / number of particles upstream of the sample)} × 100

[0036] (Pressure loss) The filter media is installed inside the duct, and air is passed through it so that the air filtration rate is 50 cm / second. The static pressure difference upstream and downstream of the filter media is read using a differential pressure gauge, and the pressure loss (Pa) is measured.

[0037] (Average coefficient of friction) The average coefficient of friction is evaluated using a friction tester (KES-SE) manufactured by Kato Tech. The sample is fixed to a table, and the contactor is swept at a speed of 1 mm / s while applying a load of 50 gf, and the detected average coefficient of friction (MIU) is calculated.

[0038] (Filter's performance in suppressing re-dispersion of airborne particles) Cut the sample into 15cm square pieces and apply JIS Class 15 dust for 5m 3 The load is applied at a rate of / min, and the load is stopped when the airflow resistance increases by 50 Pa above the base level. The amount of dust collected in the sample is evaluated by weight. A 15 cm square sample is then placed vertically on a jig on the tabletop, and a 5 m load is applied from a height of 10 cm. 3 Blowing off the dust at a rate of / min. Finally, weigh the sample to confirm the weight of the dust that fell from the sample. If the weight of the dust that fell from the sample is 30% or less of the amount of dust attached, the re-scattering suppression performance is judged to be good (○). If it exceeds 30%, the re-scattering suppression performance is judged to be poor (×).

[0039] [Example 1] Average fiber diameter 2 μm, basis weight 18 g / m 2 A melt-blown nonwoven fabric made of white polypropylene fibers that has undergone electret treatment was used as the downstream layer (long-fiber nonwoven fabric). Average particle size 250μm, BET specific surface area 950m 2 Coconut shell-based granular activated carbon (at a weight of / g), EVA resin (average particle size 250 μm, MI 20 g / 10 min, melting point 110°C) as a thermoplastic powder resin, and silica gel containing adipic acid dihydrazide were weighed in a ratio of 80:30:32. After mixing for 15 minutes using a hoop shaker (manufactured by Kyomachi Sangyo Sharyo Co., Ltd.), this mixed powder was added to the downstream layer in a total volume of 90 g / m³. 2 The material was evenly dispersed to form an intermediate layer. Add 0.3 g / m² of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond nonwoven fabric (average fiber diameter 30 μm, basis weight 40 g / m²). 2 The material was layered as the upstream layer (base layer nonwoven fabric), sandwiched between Teflon® / glass belts, and the belt spacing was set to 0.5 mm and the pressure to 100 kPa. A hot press was then performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Example 2] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.5 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond nonwoven fabric (average fiber diameter 30 μm, basis weight 40 g / m²). 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Example 3] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.1 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond nonwoven fabric (average fiber diameter 30 μm, basis weight 40 g / m²). 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Example 4] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 1.5 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond nonwoven fabric (average fiber diameter 30 μm, basis weight 40 g / m²). 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Example 5] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.5 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond nonwoven fabric (average fiber diameter 30 μm, basis weight 40 g / m²). 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Example 6] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.5 g / m² of sodium carboxymethylcellulose to the aforementioned intermediate layer. 2 Nonwoven fabric containing polyester resin manufactured by wet papermaking method (average fiber diameter 30 μm, basis weight 30 g / m²) 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Comparative Example 1] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.09 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond (average fiber diameter 30 μm, basis weight 40 g / m²) 2The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Comparative Example 2] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.4 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond (average fiber diameter 30 μm, basis weight 40 g / m²) 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Comparative Example 3] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 1.6 g / m² of sodium carboxymethylcellulose to the above intermediate layer. 2 Contains polyester spunbond (average fiber diameter 30 μm, basis weight 40 g / m²) 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Comparative Example 4] The downstream and intermediate layers were prepared in the same manner as in Example 1. Add 0.5 g / m of sodium carboxymethylcellulose to the above intermediate layer. 2 Polypropylene spunbond with an average friction coefficient of 0.10 (average fiber diameter 30 μm, basis weight 40 g / m²) 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained. [Reference example 1] Average fiber diameter 10 μm, basis weight 18 g / m 2An electret-treated spunbond nonwoven fabric made of white polypropylene fibers was used as the downstream layer. An intermediate layer similar to that in Example 1 was prepared on top of this downstream layer. Add 0.3 g / m² of sodium carboxymethylcellulose to the above intermediate layer. 2 Polyester spunbond with an average friction coefficient of 0.20 (average fiber diameter 30 μm, basis weight 40 g / m²) 2 The upper layer was stacked and sandwiched between Teflon® / glass belts. The belt spacing was set to 0.5 mm and the pressure to 100 kPa, and a hot press was performed at 110°C for 15 seconds. After cooling, the filter material was obtained.

[0040] [Table 1]

[0041] Table 1 shows that by using a filter material in which the average friction coefficient of the surface placed in the upstream layer of the filter material is 0.15 or higher, it is possible to provide a filter material that reduces the re-scattering of collected dust. [Industrial applicability]

[0042] The filter material of the present invention exhibits low re-scattering of collected dust, making it highly useful in industry. For example, it can be used in filters for automobiles, air purifiers and air conditioners, photocopiers, printers, multi-functional office automation equipment, and toilet deodorizers, significantly contributing to improved performance.

Claims

1. A filter material having a laminated structure in which a long-fiber nonwoven fabric and a base layer nonwoven fabric are laminated, The base layer nonwoven fabric contains a polyester resin, and the base layer nonwoven fabric contains a thickening agent in an amount of 0.1 g / m² to 1.5 g / m². The aforementioned base material nonwoven fabric is arranged in the outermost layer of the filter material, and the average coefficient of friction of the outermost surface is 0.15 or more, characterized in that it is a filter material.

2. The filter material for a filter according to claim 1, characterized in that the base material nonwoven fabric is a spunbond nonwoven fabric, a wet-laid nonwoven fabric, or a thermal-bonded nonwoven fabric.

3. The filter material for a filter according to claim 1, characterized in that the long-fiber nonwoven fabric is electretized.

4. The filter material for a filter according to claim 1, characterized in that the long-fiber nonwoven fabric is a melt-blown nonwoven fabric.

5. The filter material for a filter according to claim 1, characterized in that an adsorbent is sandwiched between the long fiber nonwoven fabric and the base layer nonwoven fabric.

6. A filter using the filter material described in claim 1.

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