JP2006150273A - Filter material for ultraviolet resistant air-conditioner filter and sock filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter material for an ultraviolet resistant air-conditioner filter and a sock filter which exhibit a high particle collecting efficiency against fine dust with low pressure loss, which keep the strength hardly deteriorated even if the filter material and the sock filter are used in the vicinity of an ultraviolet lamp in food processing factories, and which can be utilized for a long period of time. <P>SOLUTION: The filter material for an ultraviolet resistant air-conditioner filter is constituted of at least two layers of a layer comprising a melt blow nonwoven fabric and a layer comprising a short fiber nonwoven fabric. The sock filter is constituted of the above filter material and adopted the melt blow nonwoven material as an inner layer and the short fiber nonwoven fabric as an outer layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention is a filter material for UV-resistant air-conditioning filters suitable for filtering and supplying a large volume of air in food processing factories and the like, and more specifically, deterioration of strength and performance hardly occur even when subjected to UV irradiation, The present invention relates to a filter medium that can be used for a long time and a sock filter composed of the filter medium.

  Conventionally, what was comprised with the textile fabric as a sock filter is known. In order to improve the collection performance with the woven fabric, it is necessary to have a textured structure in order to reduce the pore size, resulting in a thick and heavy structure and high cost. For this reason, in consideration of economic efficiency, washing is performed and reused, but the length of the sock filter is usually 5 to 20 m, and washing is not easy, and for mechanical collection, In particular, there was a drawback of poor dust collection.

On the other hand, in order to solve these problems, Patent Document 1 discloses a sock filter in which a melt-blown nonwoven fabric is used as a filter cloth and a spunbond nonwoven fabric is used as a support. Polypropylene is described. However, sock filters are sometimes used in the vicinity of ultraviolet lamps in food processing plants and the like for the purpose of maintaining a sanitary environment. In such cases, in melt-blown and spunbonded nonwoven fabrics, the strength is easily reduced due to UV degradation. There was a problem that the filter had to be changed frequently.
JP-A-10-272316

  The present invention is intended to provide a filter material for a UV-resistant air-conditioning filter and a sock filter that can exhibit high particle collection efficiency with low pressure loss and also have durability against UV irradiation.

A filter medium for an ultraviolet-resistant air-conditioning filter comprising at least two layers of a layer made of a melt blown nonwoven fabric and a layer made of a short fiber nonwoven fabric.
The melt-blown nonwoven fabric is composed of polypropylene fiber and / or polyester fiber, and is further electretized.
In addition, the short fiber nonwoven fabric contains at least 50% of any one of polyester fiber and acrylic fiber.
Further, the sock filter is composed of the above-mentioned filter material for UV-resistant air-conditioning filter, and has a melt blown nonwoven fabric as an inner layer and a short fiber nonwoven fabric as an outer layer.

  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. In addition, since it has an outermost layer made of a short fiber nonwoven fabric, even when used in the vicinity of an ultraviolet lamp in a food processing factory or the like, it does not easily deteriorate in strength or deteriorate in performance due to ultraviolet rays, and can be used for a long time.

The present invention is described in detail below.
The filter medium for an ultraviolet-resistant air-conditioning filter of the present invention is a filter medium for an ultraviolet-resistant air-conditioning filter, characterized in that it is composed of at least two layers of a layer made of a melt blown nonwoven fabric and a layer made of a short fiber nonwoven fabric. Is preferred.

  The average diameter of the fibers constituting the meltblown nonwoven fabric in the present invention is preferably 0.02 dtex or more and 0.5 dtex or less. If the average diameter is smaller than 0.02 dtex, the pressure loss is too large and the particles are clogged quickly, so that it cannot withstand long-term use. On the other hand, if the average diameter is larger than 0.5 dtex, sufficient particle collection efficiency cannot be expressed for fine dust.

Further, the basis weight of the melt blown nonwoven fabric is preferably 10 g / m ² or more and 100 g / m ² or less, more preferably 20 g / m ² or more and 60 g / m ² or less. The sock filter is often installed near the ceiling of a food processing factory or the like, and if the basis weight is too large, there is a problem that the entire sock filter becomes heavy and installation work becomes difficult. If the basis weight is too small, sufficient particle collection efficiency cannot be expressed for fine dust.

  The short fiber nonwoven fabric in the present invention is a nonwoven fabric produced mainly by a dry method using short fibers. Specifically, short fibers are opened and carded to produce a web, and then bonded and entangled by needle punching or spunlace processing to obtain a nonwoven fabric.

  The average diameter of the short fibers constituting the short fiber 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, the pressure loss is too large. Also, if the average diameter is larger than 0.5 dtex, it is affected by the basis weight, but the gap between the fibers becomes too large, and the ultraviolet rays easily pass through the short fiber nonwoven fabric, and the inner layer melt blown nonwoven fabric is likely to deteriorate. It is not preferable.

The basis weight of such a short fiber nonwoven fabric is preferably 30 g / m ² or more and 150 g / m ² or less, and more preferably 50 g / m ² or more and 120 g / m ² or less. If the basis weight is smaller than this, the strength is weak and there is a problem that ultraviolet rays are easily transmitted in addition to poor processability when the filter is processed into a bag shape. Further, if the basis weight is larger than this, there is a problem that the pressure loss is increased and the weight of the sock filter is increased.

In the present invention, the short fiber nonwoven fabric is used because of its excellent durability against ultraviolet rays. The constituent fibers of the inner layer melt blown nonwoven fabric and the spunbond nonwoven fabric disclosed in Patent Document 1 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 has been reported that the structural defect in the polymer chain becomes a degradation starting point and the degradation proceeds.

  In the present invention, the melt-blown nonwoven fabric and the short-fiber nonwoven fabric may be laminated in a non-adhesive state, but bonded or laminated by a method such as heat embossing, ultrasonic adhesion, adhesion by an adhesive resin, adhesion by a thermal adhesive sheet, adhesion by a welder, etc. Is used.

  In addition to the melt blown nonwoven fabric and the short fiber nonwoven fabric, other nonwoven fabrics, nets and the like may be laminated to the filter medium for ultraviolet resistant air conditioning filter of the present invention within the range not impairing the object of the present invention.

  In the filter medium for ultraviolet-resistant air-conditioning filter of the present invention, the melt blown nonwoven fabric is preferably composed of polypropylene fiber or polyester fiber, and is preferably electretized. Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, and polylactic acid. As a method for electretization, a conventionally known charge imparting method can be used. In other words, the method of applying charge by friction and contact with a solid or liquid, the method of applying charge by colliding with charged particles such as electron beams, and the photoelectric effect by irradiating high-energy electromagnetic waves such as ultraviolet rays and X-rays. And ionizing ions generated by corona discharge, plasma and the like, and a method of injecting and adhering charges.

  In the filter medium for an ultraviolet-resistant air-conditioning filter of the present invention, the short fiber nonwoven fabric preferably contains either polyester fiber or acrylic fiber alone or in a total of 50% or more. This is because if any of the fibers is contained in an amount of 50% or more, durability during ultraviolet irradiation is further improved.

The short fiber nonwoven fabric is preferably provided with antibacterial properties, antifungal properties, and flame retardancy as required. As a method for providing them, a method of mixing antibacterial, antifungal, and flame retardant fibers as a constituent fiber of the nonwoven fabric, or an antibacterial, antifungal, and flame retardant agent is applied after the nonwoven fabric is manufactured. There is a way.

The sock filter of the present invention is composed of the above-mentioned filter medium for UV-resistant air-conditioning filter, and is characterized by having a melt blown nonwoven fabric as an inner layer and a short fiber nonwoven 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. A sock filter having a predetermined size can be manufactured by sewing the filter medium for the UV-resistant air-conditioning filter.

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

(Measurement of filtration performance of filter media)
The pressure loss was obtained by placing a filter medium sample in a duct and controlling the air filtration speed to be 10 cm / second, and reading the static pressure difference between the 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 μm.

(Manufacture of electret melt blown nonwoven fabric)
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%.

(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.

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

Example 1
Using a polyethylene terephthalate short fiber having an average diameter of 2.2 dtex, a spunlace nonwoven fabric having a basis weight of 80 g / m ² was produced. The pressure loss at 10 cm / sec of this nonwoven fabric was 8 Pa. This nonwoven fabric and the aforementioned electret meltblown nonwoven fabric are bonded by hot embossing to obtain a filter medium. A sock filter was prepared and an actual use test was conducted.

(Example 2)
Using a polyethylene terephthalate short fiber with an average diameter of 1.7 dtex and an acrylic short fiber with 3.3 dtex, a needle punched nonwoven fabric with a basis weight of 100 g / m ² was prepared at a mixing ratio of both fibers of 50%. The pressure loss at 10 cm / sec of this nonwoven fabric was 10 Pa. This nonwoven fabric and the aforementioned electret meltblown nonwoven fabric are bonded by hot embossing to obtain a filter medium. A sock filter was prepared and an actual use test was conducted.

(Comparative Example 1)
A sock filter having a diameter of 30 cm and a length of 10 m was manufactured by sewing only the above-described electret meltblown nonwoven fabric, and an actual use test was performed.

(Comparative Example 2)
A polypropylene spunbonded nonwoven fabric having an average diameter of 2.2 dtex and a basis weight of 70 g / m ² was produced. The pressure loss at 10 cm / sec of this nonwoven fabric was 9 Pa. This nonwoven fabric and the above-mentioned electret meltblown nonwoven fabric are bonded by hot embossing to form a filter medium, and the electretized meltblown nonwoven fabric side is an inner layer and the short fiber nonwoven fabric side is the outermost layer, and is 30 cm in diameter and 10 m in length. A sock filter was prepared 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. Although the ultraviolet irradiation light spot was slightly discolored to yellow, no remarkable reduction in intensity was observed. On the other hand, the sock filter of Comparative Example 1 was clearly perforated after 3 months of operation, and no atmospheric dust particles of 0.3 to 0.5 μm could be collected. In the sock filter of Comparative Example 2, the fibers of the outermost spunbond nonwoven fabric dropped out, and the strength was considerably lowered. Also, the particle collection efficiency was greatly reduced.

  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. In addition, 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 deterioration hardly occur, and it can be used for a long time.

Claims (4)

A filter medium for an ultraviolet-resistant air-conditioning filter comprising at least two layers of a layer made of a melt blown nonwoven fabric and a layer made of a short fiber nonwoven fabric. The filter material for an ultraviolet-resistant air-conditioning filter according to claim 1, wherein the melt-blown nonwoven fabric is made of polypropylene fiber and / or polyester fiber and further electretized. The filter medium for an ultraviolet-resistant air-conditioning filter according to claim 1 or 2, wherein the short fiber nonwoven fabric contains 50% or more of any one of polyester fiber and acrylic fiber. A sock filter comprising the ultraviolet-resistant air-conditioning filter material according to any one of claims 1 to 3, wherein the melt blown nonwoven fabric is an inner layer and the short fiber nonwoven fabric is an outer layer.