JPH10216433A - Nonwoven fabric for take-up type air filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a take-up type air filter having a long life at a low cost by using a filament nonwoven fabric of a specified unit weight comprising a thermoplastic fiber of a specified fiber diameter in which a specified amt. of the structural fiber consists of a core-sheath conjugate fiber and forming the filter to have specified characteristics such as initial pressure loss and dust retaining amt. SOLUTION: In the production of a nonwoven fabric used for a take-up type air filter material, a filament nonwoven fabric having 30 to 100g/m<2> unit weight is used. The nonwoven fabric consists of a thermoplastic fiber of 25 to 50μm fiber diameter in which >50wt.% of the structural fiber consists of a core-sheath conjugate fiber. The main component of the core-sheath conjugate fiber is a high melting point polymer such as polyethylene terephthalate. As for the sheath component, a polyester prepared by copolymn. of isophthalic acid is used so that the sheath acts as an adhesive component. The thickness of the nonwoven fabric is specified to 0.15 to 0.40mm. Thereby, the obtd. nonwoven fabric for a take-up type air filter has such performances as <=100Pa initial pressure drop and >=15g/m<2> dust holding amt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for a wind-up air filter, and more particularly to a nonwoven fabric having a regular arrangement of fibers, a small thickness and low pressure loss, which is the most important filter performance. The present invention relates to a nonwoven fabric for a wind-up air filter, which achieves a long life and space saving.

[0002]

2. Description of the Related Art Conventionally, as a roll-type air filter medium, a resin-bonded short-fiber nonwoven fabric made of synthetic fiber or a glass fiber filter medium has been used, but in order to achieve a low pressure loss, both are bulky types. In addition, the thickness was several mm to 20 mm, and in order to prolong the service life of the filter medium with a single winding roll, the winding type air filter device was increased in size and required a large space.

A conventional long-fiber nonwoven fabric has a fiber diameter of 1
0-20 μm, with narrow fiber gap and crimping type by hot embossing, the number of fused parts between fibers increases, and the pressure loss is large and the rigidity and Young's modulus are small. It was not used to be used.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conventional air-wound air filter medium for coarse dust, which is bulky in order to obtain a low pressure loss and a long life.
An object of the present invention is to solve the drawbacks of the prior art that a large space is required, and to provide a long-life, space-saving, low-cost nonwoven fabric for a wind-up air filter for coarse dust.

[0005]

The present invention employs the following means to solve the above-mentioned problems. That is, the present invention comprises a thermoplastic fiber having a fiber diameter of 25 to 50 μm, and 50% by weight or more of the constituent fiber is a core-sheath composite fiber,
A long-fiber nonwoven fabric having a mass per unit area of 30 to 100 g / m ^2, initial pressure loss 100Pa or less, the dust holding amount 15 g / m ²
It is a nonwoven fabric for a roll-up air filter having the above performance.

Hereinafter, the present invention will be described in detail. In the present invention, the diameter of the thermoplastic fiber must be 25 to 50 μm. It is necessary to configure the rigidity and low pressure loss as a filter medium. In particular, if it exceeds 50 μm, the dust retention cannot be maintained. Preferred fiber diameter is 30-40
μm.

It is necessary that at least 50% by weight of the constituent fibers of the thermoplastic fibers be core-sheath conjugate fibers. If it is less than 50% by weight, the adhesive strength is not sufficient, and it is easy to fluff and is not suitable for use. As the main (core) component, a relatively high-melting polymer such as polyethylene terephthalate or nylon 6,6 (polyamide 6,6) is used, and the sheath component plays a role as an adhesive component. It is necessary to have, for example, polyester copolymerized isophthalic acid, polybutylene terephthalate or a mixture thereof,
Nylon 6, polypropylene, polyethylene and the like.

[0008] basis weight of the nonwoven fabric is about 30 to 100 g / m ² is not sufficient rigidity is obtained nonwoven fabric is less than the basis weight 30 g / m ^2, also the pressure loss increases exceeds basis weight 100 g / m ² only crude Not suitable for non-woven fabric for roll-up air filters for dust.

When the initial pressure loss satisfies the condition of 100 Pa or less at a wind speed of 2.5 m / sec, a long service life of the filter medium is achieved only when the initial pressure loss exceeds 100 Pa. The increase in loss is large, and the desired long-life filter medium cannot be obtained.

Next, the amount of retained dust is 15 g / m
Must be at least ² . If the pressure is less than 15 g / m ² , the rate of increase of the pressure loss becomes too large, and as a result, the winding speed must be increased. Preferably it is 30 g / m ² or more.

The thickness of the nonwoven fabric is 0.15 to 0.40.
When the thickness is within the range of mm, it is necessary to save the space of the wind-up type air filter device, and a thermocompression bonding method is suitable as a method of adjusting the thickness. As the bonding method, a thermocompression bonding type is used.
It can be done by penetration of hot gas. When a material with high shrinkage is bonded to a single yarn, the modulus and strength of the sheet may be significantly reduced due to processing shrinkage. In such a case, it is necessary to carry out crystallization by heating in the spinning process or to use a binding type bonding machine. Adhesion by hot embossing is not preferable because not only the area of the filter is reduced but also the pressure loss is increased because of fusion between fibers.

Further, a flame retardant can be contained in the nonwoven fabric of the present invention. This makes it possible to impart heat resistance and nonwoven fabric, which are recently required for filters.

As such a flame retardant, generally known flame retardants can be used.
Bis (haloalkyl) phosphoroxy.haloalkylphosphonate shown in Chemical formula 1 described in JP-A-214 is mentioned.

[0014]

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In the present invention, the nonwoven fabric may contain a phosphorus-based flame retardant at a phosphorus concentration of 0.1 to 3% by weight based on the total weight of the nonwoven fabric. If the phosphorus concentration is less than 0.1% by weight, the desired flame retardancy cannot be maintained, while if the phosphorus concentration exceeds 3% by weight, the yarn is liable to break during spinning and stretching, and the operability decreases. In addition, the nonwoven fabric of the present invention, in which 50% or more of the constituent fibers are core-sheath conjugate fibers, is effective in adding the above flame retardant. That is, in places where the core-sheath composite fiber ratio in the nonwoven fabric constituent fiber is high, the addition of the flame retardant and the antibacterial agent may be both sheath components only. Not adding to the components has a great effect on securing operability and production cost.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the present invention. The measurement method used in the present specification is shown below. (A) Abrasion resistance A1 method (Taber method) according to JIS L-1096. Abrasion wheel NO: CS-10 Load 250gf at 500 days (b) the initial pressure loss, the dust holding amount testing apparatus: JIS Vertical Test Equipment Wind: 2.5 m / s final pressure drop: 196Pa (20mmH ₂ O) powder: JIS-Z-8901 NO15

Examples 1 to 4 Polyethylene terephthalate having an intrinsic viscosity (phenol / tetrachloroethane = 6/4 weight ratio, measured at 30 ° C.) of 0.63 was used as a core component, and terephthalic acid was used during polymerization of the polyethylene terephthalate. A mixed polymer of a copolyester and polybutylene terephthalate (mixing weight ratio 50/50) copolymerized by adding 10 to 15 mol% of isophthalic acid is used as a sheath component, and the weight ratio of the sheath component to the core component is 2: 8. Core-sheath type composite fiber, diameter 0.3 mm,
From a short nozzle having 315 orifices (holes) having a length of 0.6 mm, a temperature of 280 ° C. and a discharge rate of 0.56 g / min. A belt was stretched five times with a feed roller having a surface speed of 200 m / min and four draw rollers (the latter three heated at 85 ° C.) and a draw roller having a surface speed of 1000 m / min to obtain a polyester filament. The above polyester filament is 570m with ID
m was fed to a slit-shaped air jet device, and a web having fibers arranged in the width direction was obtained below the slit by a deflection guide plate. Next, the obtained web was sandwiched between two upper and lower net conveyors, and hot air of 240 ° C. and 4.3 m / s was passed therethrough to melt the sheath component polymer and bond the core component polyethylene terephthalate filament. The thus obtained long-fiber nonwoven fabrics of Examples 1 to 4 (basis weight 40 to 10
0 g / m ² ) is shown in Table 1.

[0018]

[Table 1]

Comparative Example 1 A nonwoven fabric (regular type) having a basis weight of 40 g / m ² in which polyester filaments having a fiber diameter of 14 μm were randomly arranged was subjected to thermocompression bonding, and the physical properties thereof are shown in Table 1. The thermocompression bonding conditions are as follows. Linear pressure is 6 at 250 ° C
Thermocompression bonding was performed between an embossing roll of 0 kg / cm and a flat roll.

Comparative Example 2 A short fiber non-woven fabric was prepared in which the intersections of polyester short fibers (average fiber length 60 mm) having an average fiber diameter of 35 μm were bonded with a thermoplastic binder (vinylidene chloride), and the physical properties thereof are shown in Table 1.

Comparative Example 3 The physical properties of a glass fiber filter material having an average fiber diameter of 35 μm for a roll filter (thickness: 50 mm, basis weight: 600 g / m ² , bulk height: 83 cm ³ / g) are also shown in Table 1.

The following is confirmed from Table 1. It was confirmed that the thickness is thin and low pressure loss, long life and space saving, which are the most important performances as filter performance, can be achieved.

[0023]

The nonwoven fabric for a roll-type air filter according to the present invention has the effects of long life, space saving, and low cost disposable, and can be greatly applied to the dust field.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Nishimura 1-1-1, Nadamachi, Iwakuni-shi, Yamaguchi Prefecture Inside the Iwakuni Plant (72) Inventor Kimio Kawado 1-1-1, Nadamachi, Iwakuni-shi, Yamaguchi Prefecture Toyobo Inside Iwakuni Plant

Claims (3)

[Claims] 1. A long-fiber nonwoven fabric comprising a thermoplastic fiber having a fiber diameter of 25 to 50 μm, wherein at least 50% by weight of a constituent fiber is a core-sheath conjugate fiber, and a long-fiber nonwoven fabric having a basis weight of 30 to 100 g / m ^2. 100Pa or less, dust holding amount 15g
/ M ² nonwoven fabric for roll-up air filters. 2. The nonwoven fabric for a roll-type air filter according to claim 1, wherein the thickness of the nonwoven fabric is 0.15 to 0.4 mm. 3. The nonwoven fabric for a roll-type air filter according to claim 1, wherein the phosphorus-based flame retardant is contained in a concentration of 0.1 to 3% by weight based on the total weight of the nonwoven fabric.