JP2006192345A - Filter medium for ultraviolet-resistant air-conditioning filter, and sock filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an incombustible filter medium for an ultraviolet-resistant air-conditioning filter realizing a high particle collection efficiency with a low pressure drop, having gradual pressure drop increase due to dust clogging, and to provide a sock filter composed of the filter medium. <P>SOLUTION: This filter medium for the ultraviolet-resistant air-conditioning filter is composed of a filter medium containing triboelectric charging nonwoven fabric. The triboelectric charging nonwoven fabric comprises at least 20 mass% polyester-based fiber containing phosphinic compound and/or sulfonic compound, and at least 30 mass% polyolefin fiber. The sock filter is composed of the filter medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a filter medium for an ultraviolet-resistant air-conditioning filter suitable for filtering and supplying a large volume of air in a food processing factory or the like. That is, the present invention relates to a filter medium for an ultraviolet-resistant air-conditioning filter that can exhibit high particle collection efficiency with low pressure loss, has a moderate increase in pressure loss due to dust clogging, and has flame retardancy, and a sock filter composed of the filter medium.

  Conventionally, a sock filter made of a woven fabric has been used, and as the configuration, a structure with a texture is adopted to reduce the pore size in order to ensure sufficient collection performance. . However, as a result of adopting such a structure, there is a problem that the filter is thick and heavy and has a high pressure loss. In addition, the cost is high, so it is reused by washing, but the length of the sock filter is usually 5 to 20 m, which is not easy, and in addition, it is particularly easy to collect fine dust for mechanical collection. There was a drawback of being scarce.

On the other hand, in order to solve these problems, a sock filter using an electret meltblown nonwoven fabric as a filter cloth and a spunbond nonwoven fabric as a support has been proposed, and both meltblown nonwoven fabric and spunbond nonwoven fabric are disclosed as polypropylene. (For example, refer to Patent Document 1). However, while the electret meltblown nonwoven fabric exhibits excellent collection performance against fine dust, there is a problem that the pressure loss increases quickly due to dust clogging. Furthermore, these sock filters may be used in the vicinity of ultraviolet lamps for the purpose of maintaining a sanitary environment in food processing factories and the like. Because of this, there was a problem that the filter had to be changed frequently.
JP-A-10-272316

By the way, a frictionally charged nonwoven fabric in which different types of fibers are mixed has attracted attention as a filter medium having a low pressure loss and a relatively high particle collection efficiency, and so far, various combinations of fiber configurations have been proposed (for example, (See Patent Documents 2 to 4).
US Pat. No. 4,798,850 JP 2000-170068 A Special table 2003-512147 gazette

These filter media have been proposed in which a combination of polyolefin fibers and modacrylic, acrylic, and polyester fibers is obtained by removing the oil agent from the fibers to clean the surface and then triboelectrically charging. However, none of the literature discusses the flammability of the filter medium, and it may not be used depending on the application. For example, when used for an air purifying unit in an automobile interior, it is essential that the combustibility classification according to “JIS D 1201 (1977) Method for testing the flammability of organic materials for automobile interiors” is self-extinguishing. However, among the fiber configurations of conventional filter media, the combination of polyolefin fibers and acrylic fibers is not self-extinguishing because acrylic fibers are extremely flammable, although the filtration performance is high. The combination of polyolefin fiber and modacrylic fiber exhibits self-extinguishing properties, but modacrylic contains chlorine and is not environmentally preferable because it may generate harmful dioxins during incineration.

  In addition, the combination of polyolefin fibers and standard aromatic polyester fibers (hereinafter referred to as standard polyester fibers) is less flammable than the combination of polyolefin fibers and acrylic fibers, but does not necessarily exhibit self-extinguishing properties. There is a problem that the filtration performance is also poor. Furthermore, although a filter medium composed of polyolefin fibers and polyester fibers has been disclosed, it cannot be said that the chargeability is sufficient, and in particular, the collection efficiency of fine particles of about 0.3 mμ is not sufficient, and high filtration performance and self-extinguishing. No investigation has been made on the structure of the polyester for expressing the properties.

  The present invention relates to a filter medium for an ultraviolet-resistant air-conditioning filter that can exhibit high particle collection efficiency with low pressure loss, has a moderate increase in pressure loss due to dust clogging, and has flame retardancy, and a sock filter composed of the filter medium Is intended to provide.

The present invention is composed of a frictionally charged non-woven fabric comprising at least 20% by mass of a polyester fiber containing a phosphinic acid compound and / or a sulfonic acid compound and at least 30% by mass of a polyolefin fiber. This is a filter medium for air conditioning filters.
In the polyester fiber contained in the frictionally charged non-woven fabric, the filter material for an ultraviolet-resistant air-conditioning filter is characterized in that a phosphinic acid compound and / or a sulfonic acid compound are copolymerized with a polyester molecular chain.
The frictionally charged non-woven fabric is a filter medium for an ultraviolet-resistant air-conditioning filter, wherein the combustibility classification according to the flammability test method for organic materials for automobile interiors is self-extinguishing property according to JIS D 1201 (1977).
Furthermore, it is a sock filter which is comprised by the said filter medium for ultraviolet-resistant air-conditioning filters, and uses a friction charging nonwoven fabric as an outer layer.

  The filter material for an ultraviolet-resistant air-conditioning filter of the present invention can exhibit high particle collection efficiency with respect to fine dust with low pressure loss. Moreover, since the frictionally charged non-woven fabric is a relatively bulky non-woven fabric composed of short fibers, the increase in pressure loss due to dust clogging is moderate. Even when used in the vicinity of an ultraviolet lamp in a food processing factory or the like, strength deterioration and performance deterioration due to ultraviolet rays hardly occur, and it can be used for a long period of time. In addition, the filter medium itself is self-extinguishing according to JIS D 1201 (1977) automotive interior material flammability test method, and has both flame retardancy.

The present invention is described in detail below.
The present invention is an ultraviolet-resistant air-conditioning filter medium comprising a filter medium containing a frictionally charged nonwoven fabric, and the frictionally charged nonwoven fabric contains at least 20% by mass of a polyester fiber containing a phosphinic acid compound and / or a sulfonic acid compound. A filter medium for an ultraviolet-resistant air-conditioning filter, which is a nonwoven fabric containing at least 30% by mass of a polyolefin fiber.

（式中、Ｘ¹はエステル形成性官能基、Ｒ¹は低級アルキレン基あるいはアリーレン（Ａｒｙｌｅｎｅ）基、Ｒ²、Ｒ³は同一もしくは異なる炭素数１〜１０の炭化水素基、ｎ₁は１または２の整数、びｎ₂、ｎ₃はそれぞれ０〜４の整数を表す。） The phosphinic acid compound in the present invention is preferably a compound represented by the following general formula (1).

Wherein X ¹ is an ester-forming functional group, R ¹ is a lower alkylene group or an arylene group, R ² and R ³ are the same or different hydrocarbon groups having 1 to 10 carbon atoms, and n ₁ is 1 or (The integers ₂ and n ₂ and n ₃ each represent an integer of 0 to 4.)

（式中、Ｘ²はエステル形成性官能基、Ｘ³はＸ²と同一もしくは異なるエステル形成性官能基あるいは水素原子、Ａ¹は芳香族または脂肪族の基、Ｍ¹はアルカリ金属またはアルカリ土類金属を示す。）

（式中、Ｘ⁴はエステル形成性官能基、Ｘ⁵はＸ⁴と同一もしくは異なるエステル形成性官能基あるいは水素原子、Ａ²は芳香族または脂肪族の基、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷は水素、アルキル基、アリール（Ａｒｙｌ）基、ヒドロキシアルキル基から選ばれた同一または異なる基、ｎ₄は１または２の整数を示す。） The sulfonic acid compound in the present invention may be a sulfonic acid metal salt represented by the following general formula (2) or a sulfonic acid phosphonium salt represented by the following general formula (3).

Wherein X ² is an ester-forming functional group, X ³ is the same or different ester-forming functional group or hydrogen atom as X ² , A ¹ is an aromatic or aliphatic group, M ¹ is an alkali metal or alkaline earth Indicates a similar metal.)

Wherein X ⁴ is an ester-forming functional group, X ⁵ is the same or different ester-forming functional group or hydrogen atom as X ⁴ , A ² is an aromatic or aliphatic group, R ⁴ , R ⁵ , R ⁶ R ⁷ is the same or different group selected from hydrogen, an alkyl group, an aryl group, and a hydroxyalkyl group, and n ₄ represents an integer of 1 or 2.)

In the present invention, in the general formula (1), X ¹ is specifically a carboxyl group, an alkyl ester having 1 to 6 carbon atoms in the carboxyl group, a cycloalkyl ester, an aryl (Aryl) ester, a hydroxyl group, and 2 carbon atoms. -7 hydroxyl alkoxycarbonyl groups and the like. Preferred examples of R ¹ include lower alkylene groups such as methylene, ethylene, 1,2-propylene and 1,3-propylene, and arylene groups such as 1,3-phenylene and 1,4-phenylene. . Preferred examples of R ² and R ³ include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, an aryl group, and the monovalent group of X ¹ described above.

Specific examples of the phosphinic acid compound represented by the general formula (1) include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA) and other chemical formulas (a ) To (z).

（式中、Ｒ⁸は炭素数１以上２２以下のアルキル基、フェニル基、ナフチル基およびアントラセン基を示し、Ｍ²は金属イオン、アンモニウムイオン、ホスホニウムイオンを示す。） Further, as the phosphinic acid compound, in addition to the above, a compound of the following general formula (4) and a carboxyphosphinic acid represented by the general formula (5) and derivatives thereof are also effective.

(In the formula, R ⁸ represents an alkyl group having 1 to 22 carbon atoms, a phenyl group, a naphthyl group, and an anthracene group, and M ² represents a metal ion, an ammonium ion, or a phosphonium ion.)

Specific examples of the compound represented by the general formula (4) include sodium phenylphosphinate, potassium phenylphosphinate, lithium phenylphosphinate, calcium phenylphosphinate, magnesium phenylphosphinate and the like.

（式中、Ｒ¹¹ は炭素原子数４以上の分岐したアルキル基または芳香族基、Ｒ¹² 、Ｒ¹³ は水素原子または炭素原子数１〜６の１価の有機基またはヒドロキシル基を有する有機基で互いに同じでも違っていてもよい。また、Ａ³は２価または３価の有機残基を表す。）

(Wherein R ¹¹ is a branched alkyl group or aromatic group having 4 or more carbon atoms, R ¹² and R ¹³ are hydrogen atoms, monovalent organic groups having 1 to 6 carbon atoms or organic groups having a hydroxyl group. And A ³ represents a divalent or trivalent organic residue.)

Specific examples of the carboxyphosphinic acid represented by the general formula (5) and derivatives thereof include (2-carboxyethyl) phenylphosphinic acid, (2-carboxyethyl) -tertbutylphosphinic acid, (2-carboxyethyl) 1, 1-dimethylhexylphosphinic acid, (2-carboxyethyl) naphthylphosphinic acid, (2-carboxyethyl) toluylphosphinic acid, (2-carboxyethyl) 2,5-dimethylphenylphosphinic acid, (2-carboxyethyl) cyclohexylphosphine Acid, (2-carboxyethyl) -4-chlorophenylphosphinic acid, (4-carboxyphenyl) phenylphosphinic acid, (3-carboxyphenyl) phenylphosphinic acid, carboxymethylphenylphosphinic acid, carboxymethylnaphthylphos Fin acids and their lower alcohol esters, lower alcohol diester, and a cyclic anhydride.

In the general formula (2), which is a sulfonic acid compound in the present invention, X ² represents an ester-forming functional group, and X ³ represents the same or different ester-forming functional group or hydrogen atom as X ² . Specific examples of the ester-forming functional group include -COOH, -COOR, -OH, -OR [wherein R is a lower alkyl group or a phenyl group]. In addition, as a lower alkyl group represented by R, the linear or branched thing whose carbon number is 1-4, for example is preferable. A ¹ represents an aromatic or aliphatic group, and among them, an aromatic group is preferable. M ¹ represents an alkali metal or an alkaline earth metal. Examples of the alkali metal include sodium, potassium, and lithium, and examples of the alkaline earth metal include calcium and magnesium.

  The sulfonic acid compound represented by the general formula (2) may be added as a reaction product with glycol. Particularly preferred examples of such sulfonic acid compounds include 5-sodium sulfoisophthalic acid (and its methyl ester, ethylene glycol ester), m-sodium sulfobenzoic acid (and its methyl ester, ethylene glycol ester), p-sodium sulfobenzoic acid. Acid (and its methyl ester, ethylene glycol ester), o-sodium sulfobenzoic acid (and its methyl ester, ethylene glycol ester), 4-hydroxy-3-sodium sulfobenzoic acid (and its methyl ester, ethylene glycol ester), 3-hydroxy-4-sodiumsulfobenzoic acid (and its methyl ester, ethylene glycol ester), 3-sodium sulfosalicylic acid (and its methyl ester, ethylene Mention may be made of a recall ester), and the like.

In the present invention, in the general formula (3), X ⁴ represents an ester-forming functional group, and X ⁵ represents the same or different ester-forming functional group or hydrogen atom as X ⁴ . Specific examples of the ester-forming functional group include -COOH, -COOR, -OH, -OR [wherein R is a lower alkyl group or a phenyl group]. In addition, as a lower alkyl group represented by R, the linear or branched thing whose carbon number is 1-4, for example is preferable. A ¹ represents an aromatic or aliphatic group, and among them, an aromatic group is preferable.

R ⁴ , R ⁵ , R ⁶ and R ⁷ represent the same or different groups selected from the group consisting of hydrogen, alkyl groups, aryl groups, and hydroxyalkyl groups. Such sulfonic acid phosphonium salts can be easily synthesized by a reaction between a corresponding sulfonic acid and a phosphine or a reaction between a corresponding sulfonic acid metal salt and a phosphonium halide.

The sulfonic acid phosphonium salt represented by the general formula (3) may be added as a reaction product with glycol. Preferred examples of the sulfonic acid phosphonium salt include tetrabutylphosphonium salt of 3,5-dicarboxybenzenesulfonic acid, ethyltributylphosphonium salt of 3,5-dicarboxybenzenesulfonic acid, and benzyltributyl 3,5-dicarboxybenzenesulfonic acid. Phosphonium salt, 3,5-dicarboxybenzenesulfonic acid phenyltributylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid tetraphenylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid ethyltriphenylphosphonium salt, 3,5- Dibutylbenzenesulfonic acid butyltriphenylphosphonium salt, 3,5-dicarboxybenzenesulfonic acid benzyltriphenylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonic acid tetra Tylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonic acid ethyl tributylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonic acid benzyltributylphosphonium salt, 3-carbomethoxybenzenesulfonic acid tetrabutylphosphonium salt, 3-carbomethoxy Benzenesulfonic acid tetraphenylphosphonium salt, 3,5-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, 3,5-di (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetraphenylphosphonium salt, 3- (Β-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, 3- (β-hydroxyethoxycarbonyl) benzenesulfonic acid tetraphenylphosphonium salt, 4-hydride Examples include roxyethoxybenzenesulfonic acid tetrabutylphosphonium salt, 2,6-dicarboxynaphthalene-4-sulfonic acid tetrabutylphosphonium salt, and α-tetrabutylphosphonium succinic acid. Two or more of the sulfonic acid phosphonium salts may be used in combination.

In the present invention, the phosphinic acid compound and / or sulfonic acid compound is preferably copolymerized with a polyester molecular chain. The polyester molecular chain has at least one selected from terephthalic acid or an ester-forming derivative thereof in the dicarboxylic acid component and 80% or more in the glycol component from ethylene glycol, trimethylene glycol, and tetramethylene glycol. Those derived from certain alkylene glycols or ester-forming derivatives thereof. The content of the phosphinic acid compound and / or sulfonic acid compound in the copolymer is 0.5 to 5 mol%, preferably 1 to 3 mol% of the total carboxylic acid component as the phosphinic acid compound and sulfonic acid compound. The phosphinic acid compound and the sulfonic acid compound may coexist in the same polyester molecular chain. In the production of these copolyesters, conventionally known catalysts and reaction conditions can be employed for both the ester exchange reaction and the polycondensation reaction. In addition, short fibers can be produced by a conventional method using these copolyester resins as raw materials.

  The copolyester fiber is mixed with a polyolefin-based fiber, and a charged charge is generated by rubbing the fibers with an appropriate method. However, the charge level is much higher than when standard polyester fiber is used. Therefore, the frictionally charged nonwoven fabric of the present invention is characterized in that the particle collecting performance is superior to the frictionally charged nonwoven fabric of standard polyester fiber and polyolefin fiber.

Further, the copolymerized polyester fiber is excellent in flame retardancy as compared with a standard polyester fiber. It is considered that this is because the phosphinic acid compound and / or the sulfonic acid compound is contained in the polymer, so that the drip property at the time of combustion is developed and contributes to the flame retardant effect. Therefore, the triboelectrically charged nonwoven fabric of the present invention can easily be self-extinguishing according to “JIS D 1201 (1977) Method for testing the flammability of organic materials for automobile interiors”.

Examples of the polyolefin fiber in the present invention include polyethylene fiber, polypropylene fiber, and polyethylene-polypropylene composite fiber, and polypropylene fiber is preferable. These polyolefin fibers may contain a flame retardant.

In order to increase the electrification level due to friction in the frictionally charged nonwoven fabric, it is considered effective to increase the contact frequency between different fibers and increase the amount of charge generated by the contact. Among the latter, as described above, the charge level is increased by mixing and rubbing the copolymerized polyester fiber and the polyolefin fiber. Regarding the former, there is an optimum region of the mixing ratio of the polyester fiber and the polyolefin fiber, and the charge level does not increase if it is outside this range.

Therefore, in this invention, it is preferable that the said polyester fiber containing a phosphinic acid compound and / or a sulfonic acid compound is contained 20 mass% or more with respect to all the constituent fibers. If it is less than 20% by mass, the effect of increasing the charge and the effect of making it flame-retardant are not sufficient. It is especially preferable that it is 30-70 mass%.

  In the present invention, the polyolefin fiber content is preferably 30% by mass or more, and preferably 30 to 70% by mass with respect to all the constituent fibers in order to develop a charging effect due to friction.

The frictionally charged nonwoven fabric of the present invention may contain other fibers in addition to the polyester fiber and the polyolefin fiber containing a phosphinic acid compound and / or a sulfonic acid compound. Suitable fibers include standard polyester fibers, polylactic acid fibers, acrylic fibers and the like.

  The average diameter of the short fibers constituting the frictionally charged nonwoven fabric is preferably 1.1 dtex or more and 6.7 dtex or less. When the average diameter is smaller than 1.1 dtex, pressure loss is large and dust clogging is likely to occur. Further, when the average diameter is larger than 6.7 dtex, the particle collecting performance is low, and sufficient characteristics as a filter medium for an air conditioning filter and a sock filter are hardly exhibited.

The basis weight of the frictionally charged nonwoven fabric is preferably 30 g / m ² or more and 200 g / m ² or less, and more preferably 50 g / m ² or more and 150 g / m ² or less. If the basis weight is smaller than this, the particle collecting performance as a filter medium for an air conditioning filter is not sufficient, and the strength is weak and the processability when processing the filter into various shapes is poor. Further, if the basis weight is larger than this, the pressure loss becomes large, and there is a problem that the whole weight becomes heavy when used as a sock filter suspended from the ceiling.

In addition to the friction-charged non-woven fabric, other non-woven fabrics and nets may be laminated on the filter medium for ultraviolet resistant air-conditioning filter of the present invention as long as the object of the present invention is not impaired. These materials may have various functions such as antibacterial, antifungal and flame retardant properties as required.

An example of a suitable method for producing the filter medium for an ultraviolet resistant air conditioning filter of the present invention will be described below. First, the frictionally charged non-woven fabric is produced by the following procedure. A plurality of short fiber components including the short fibers are mixed and carded at a predetermined mass mixing ratio to produce a mixed fiber web, and then entangled by a needle punch, a water punch or the like. Thereafter, the oil agent is removed by a scouring process. Next, the dried web is subjected to friction treatment to obtain a frictionally charged nonwoven fabric. As a method of friction processing, for example, there are a method of performing friction while meshing and passing a nonwoven fabric between two gear rolls, and a method of simultaneously performing friction and confounding using needle punch processing. In these friction processes, the web can be stretched and adjusted to a predetermined basis weight at the same time as the charging process, or can be bonded to a reinforcing material. As the reinforcing material, conventionally known materials such as a net, a spunbond nonwoven fabric, a thermal bond nonwoven fabric, a melt blown nonwoven fabric, and a wet papermaking paper can be used.

The sock filter of the present invention is constituted by the above-mentioned filter medium for UV-resistant air-conditioning filter, and is characterized by using a frictionally charged non-woven fabric as an outer layer. A sock filter is a cylindrical duct-type filter used in air-conditioning equipment such as food processing factories. It collects dust and bacteria in the factory and makes the air velocity at the outlet low and uniform. It is a filter that has the effect of preventing a decrease in the temperature of the body. It is important to design the frictionally charged non-woven fabric as an outer layer and to irradiate this layer with ultraviolet rays. A sock filter of a predetermined size can be manufactured by sewing a filter medium for an ultraviolet-resistant air-conditioning filter.

The filter medium and the sock filter for ultraviolet-resistant air-conditioning filter of the present invention are more durable against ultraviolet rays than a sock filter configured by laminating a melt blown nonwoven fabric and a spunbond nonwoven fabric as disclosed in Patent Document 1, for example. There is an advantage of being excellent. The constituent fibers of the meltblown nonwoven fabric and the spunbond nonwoven fabric are substantially undrawn yarns, and a number of structural defects remain in the polymer chain. In contrast, short fibers are stretched by a hot roll or the like after spinning, so that oriented crystallization advances and structural defects in the polymer chain are considerably reduced. Although the mechanism of UV degradation has not been completely elucidated, it is presumed that the structural progress in the polymer chain becomes a degradation starting point and the degradation proceeds.

  Hereinafter, the present invention will be described in detail by way of examples.

(Manufacture of copolyester fiber)
(Production Example 1)
194 parts by mass of dimethyl terephthalate (DMT), 124 parts by mass of ethylene glycol, and 2 mol% of the phosphinic acid compound of the compound (r) with respect to DMT were put in a reaction vessel, and 0.1 mol% of DMT was added thereto. Zinc acetate and 0.02 mol% antimony trioxide were added, and the ester exchange reaction was carried out while raising the temperature from 150 ° C. to 230 ° C. over 2 hours in a nitrogen gas atmosphere. Next, this product was transferred to a polycondensation can and subjected to a polycondensation reaction at 280 ° C. under a reduced pressure of 1 mmHg or less for 5 hours to obtain a copolyester resin. Using this resin as a raw material, 2.2 dtex short fiber A was produced by a conventional method.

(Production Example 2)
194 parts by mass of dimethyl terephthalate (DMT), 124 parts by mass of ethylene glycol, and 3 mol% of ethylene glycol ester of 5-sodium sulfoisophthalic acid with respect to DMT were put in a reaction vessel, and 0.1 mol with respect to DMT was added thereto. % Zinc acetate and 0.02 mol% antimony trioxide were added, and the ester exchange reaction was carried out while raising the temperature from 150 ° C. to 230 ° C. over 2 hours in a nitrogen gas atmosphere. Next, this product was transferred to a polycondensation can and subjected to a polycondensation reaction at 280 ° C. under a reduced pressure of 1 mmHg or less for 5 hours to obtain a copolyester resin. Using this resin as a raw material, 2.2 dtex short fiber B was produced by a conventional method.

(Method for producing frictionally charged nonwoven fabric)
A blended web having a predetermined basis weight was prepared by blending short fibers having a predetermined mass mixing ratio, carding, and water punching. This mixed fiber web was subjected to a scouring treatment using an open soap scourer at a sodium hydroxide of 2 g / liter, a nonionic surfactant of 1 g / liter, and a liquid temperature of 90 ° C., and then washed with hot water and dried. Further, a needle punching process was performed at a needle density of 50 / cm ² , and friction charging and entanglement were performed simultaneously to obtain a frictionally charged nonwoven fabric. The temperature and humidity during the needle punching process were 27 ° C. and 55 RH%.

(Measurement of filtration performance of non-woven filter media)
The pressure loss was determined by placing a nonwoven fabric sample in a duct and controlling the air filtration speed to be 10 cm / second, and reading the static pressure difference upstream and downstream of the filter medium with a pressure gauge. The particle collection efficiency (%) was evaluated at 10 cm / second using NaCl particles having a particle diameter of 0.3 to 0.5 μm.

(Flammability evaluation)
It was carried out in accordance with JIS D 1201 (1977) flammability test method for organic materials for automobile interiors. The number of test points was 5 in each MD direction and TD direction of each nonwoven fabric.

(Sock filter actual use test)
A sock filter was installed in the food processing factory, and 30 Nm ³ / min of air was circulated with a blower. Six UV germicidal lamps (GL-30) are installed in the longitudinal direction of the sock filter at a distance of about 30 cm from this sock filter, and only when there are no workers in the factory (8 hours per day) Irradiated. First, a sock filter was installed and one hour after the operation of the blower, air was sampled in the immediate vicinity of the outermost layer near the germicidal lamp, and the atmospheric dust particle concentration (N) at the particle counter was measured. In addition, the atmospheric dust particle concentration (N ₀ ) of 0.3 to 0.5 μm in the outside air was measured in the same manner, and the particle collection efficiency (%) was calculated by Equation 1 to obtain the initial performance. After operating the sock filter for 3 months, air is sampled at the same location as the initial performance measurement, and the air dust particle concentration of 0.3 to 0.5 μm is measured in the same manner to collect the particles (%). Was calculated. Thereafter, the sock filter was removed, and the filter medium at a portion not irradiated with ultraviolet rays was cut out, and the pressure loss at 10 cm / second of the nonwoven fabric filter medium was measured.

(Equation 1) Particle collection efficiency (%) = [1- (N / N ₀ )] × 100

Example 1
Using the above-mentioned short fibers A and polypropylene short fibers having an average diameter of 1.7 dtex (NC manufactured by Ube Nitto Kasei), a triboelectrically charged nonwoven fabric having a basis weight of 120 g / m ² was prepared at a mixing rate of 50% by the above-described method. The pressure loss at 10 cm / sec of this nonwoven fabric was 12 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 95%. Further, as a result of the flammability evaluation, self-extinguishing properties were exhibited in both the MD and TD directions. This nonwoven fabric was sewn into a sock filter having a diameter of 30 cm and a length of 10 m, and an actual use test was conducted.

(Example 2)
Using the above-mentioned short fibers B and the same polypropylene short fibers as in Example 1, a frictionally charged nonwoven fabric having a basis weight of 100 g / m ² was prepared at a mixing rate of 50% by the above-described method. The pressure loss at 10 cm / sec of this nonwoven fabric was 10 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 93%. Further, as a result of the flammability evaluation, self-extinguishing properties were exhibited in both the MD and TD directions. This nonwoven fabric was sewn into a sock filter having a diameter of 30 cm and a length of 10 m, and an actual use test was conducted.

(Comparative Example 1)
While supplying a polypropylene melt blown nonwoven fabric having an average fiber diameter of 0.03 dtex and a basis weight of 30 g / m ² onto an earth drum, a corona discharge treatment was performed at an electric field strength of +20 kV / cm using a needle electrode to perform an electret treatment. The pressure loss of this nonwoven fabric at 10 cm / sec was 60 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 98%. Further, as a result of the flammability evaluation, self-extinguishing properties were exhibited in both the MD and TD directions. This nonwoven fabric was sewn into a sock filter having a diameter of 30 cm and a length of 10 m, and an actual use test was conducted.

(Comparative Example 2)
The electret meltblown nonwoven fabric of Comparative Example 1 and a polypropylene spunbond nonwoven fabric having an average diameter of 2.2 dtex and a basis weight of 70 g / m ² were laminated and bonded by hot embossing. The pressure loss of this nonwoven fabric at 10 cm / sec was 75 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 98%. Further, as a result of the flammability evaluation, self-extinguishing properties were exhibited in both the MD and TD directions. Next, a sock filter having a diameter of 30 cm and a length of 10 m was prepared by sewing a sewing machine so that the electret meltblown nonwoven fabric side was the inner layer and the spunbond nonwoven fabric was the outer layer, and an actual use test was performed.

(Comparative Example 3)
Using only the polypropylene short fibers used in Examples 1 and ^2, a frictionally charged nonwoven fabric having a basis weight of 120 g / m ² was prepared by the above-described method. The pressure loss at 10 cm / sec of this nonwoven fabric was 12 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 33%. Further, as a result of the flammability evaluation, self-extinguishing properties were exhibited in both the MD and TD directions. This nonwoven fabric was sewn into a sock filter having a diameter of 30 cm and a length of 10 m, and an actual use test was conducted.

(Comparative Example 4)
Using a polypropylene short fiber used in Examples 1 and 2 and a standard polyester short fiber of 2.2 dtex (707, manufactured by Toyobo Co., Ltd.), a frictionally charged non-woven fabric having a basis weight of 120 g / m ² was produced in the same manner as in Example. . The pressure loss at 10 cm / second of this nonwoven fabric was 12 Pa, and the collection efficiency of NaCl particles of 0.3 to 0.5 μm was 58%. Moreover, as a result of the flammability evaluation, it showed flammability in the MD direction and slow flammability in the TD direction. This nonwoven fabric was sewn into a sock filter having a diameter of 30 cm and a length of 10 m, and an actual use test was conducted.

The actual use test results of the sock filters of Examples and Comparative Examples are shown in Table 1. The sock filter of the example showed excellent particle collection efficiency both at the initial stage and after three months of operation. There was a slight increase in UV and pressure loss after 3 months. The irradiated portion of the line germicidal lamp was slightly discolored to yellow, but no noticeable decrease in strength was observed. On the other hand, after 3 months of operation, the sock filter of Comparative Example 1 had a large hole at the ultraviolet irradiation site, and no atmospheric dust particles of 0.3 to 0.5 μm could be collected. In the sock filter of Comparative Example 2, the spunbond nonwoven fabric fibers in the outer layer of the filter medium were pulverized, and the strength of the meltblown nonwoven fabric in the inner layer was considerably reduced. Also, the particle collection efficiency was greatly reduced. In Comparative Examples 1 and 2, the pressure loss of the cut filter media was greatly increased due to the clogging of dust in the meltblown layer. The sock filter of Comparative Example 3 had a low particle collection efficiency from the beginning. In Comparative Example 4, the filtration characteristics were slightly poor, and the filter medium did not exhibit self-extinguishing properties.

  The filter medium for ultraviolet-resistant air-conditioning filter and the sock filter of the present invention can exhibit high particle collection efficiency with respect to fine dust with low pressure loss. Moreover, since the frictionally charged non-woven fabric is a relatively bulky non-woven fabric composed of short fibers, the increase in pressure loss due to dust clogging is moderate. Even when used in the vicinity of ultraviolet lamps in food processing factories, etc., it is a UV-resistant air-conditioning filter medium and sock filter that is resistant to UV-induced strength deterioration and performance degradation, can be used for a long time, and has flame resistance. is there.

Claims (4)

A UV-resistant air-conditioning filter comprising a frictionally charged nonwoven fabric comprising at least 20% by mass of a polyester fiber containing a phosphinic acid compound and / or a sulfonic acid compound and at least 30% by mass of a polyolefin fiber. Filter media. The filter medium for an ultraviolet-resistant air-conditioning filter according to claim 1, wherein a phosphinic acid compound and / or a sulfonic acid compound is copolymerized with a polyester molecular chain in the polyester fiber contained in the frictionally charged nonwoven fabric. The anti-ultraviolet ray according to claim 1 or 2, wherein the frictionally charged non-woven fabric is self-extinguishing according to a flammability classification method according to a flammability test method for organic materials for automobile interiors of JIS D 1201 (1977). Filter medium for air conditioning filters. A sock filter comprising the ultraviolet-resistant air-conditioning filter material according to any one of claims 1 to 3, wherein a frictionally charged non-woven fabric is used as an outer layer.