JP5022987B2 - Spunbond nonwoven fabric and air filter using the same - Google Patents

Description

  The present invention relates to a spunbond nonwoven fabric. In particular, when used as an air filter, the present invention relates to a spunbonded nonwoven fabric that can exhibit high collection performance with low pressure loss and an air filter using the spunbonded nonwoven fabric.

  Conventionally, an air filter has been used to remove pollen, dust, and the like in a gas, and a fiber sheet is often used as a filter medium.

  The performance required for the air filter is a high collection performance capable of collecting a large amount of micro dust and a low pressure loss characteristic with low resistance when gas passes through the inside of the air filter.

  The collection mechanism of the air filter is mainly due to physical action such as Brownian diffusion, shielding, and inertial collision. Therefore, in order to obtain a filter medium having high collection performance, for example, a fiber sheet that is configured like a melt blown nonwoven fabric. Is relatively fine, but on the other hand, the pressure loss increases as the fiber density in the sheet increases.

  Further, in order to obtain a filter medium having a low pressure loss, for example, it is suitable that the fiber sheet to be configured has a relatively large fineness, such as a short fiber nonwoven fabric or a spunbond nonwoven fabric. Since the gap between the fibers is widened, the collection performance is lowered.

  Thus, having high collection performance and having low pressure loss characteristics are in a contradictory relationship, and it is difficult to achieve both.

  For this reason, in general, the usage is selected depending on the type of fiber sheet, such as a fine sheet for applications that emphasize high collection performance and a thick sheet for applications that emphasize low pressure loss characteristics.

  By the way, the technique which improves a collection performance is known by charging a fiber sheet and utilizing an electrostatic action in addition to a physical action. For example, an electret fibrous sheet that is continuously electretized by applying a high voltage with a non-contact type application electrode while moving the ground electrode and the fiber sheet together while the fibrous sheet is in contact with the ground electrode Has been proposed (Patent Document 1). This is because the non-woven fabric is polarized by causing electron injection, ion movement, dipole orientation, and the like, thereby imparting a charge to the fiber.

  The fiber sheet described in the example of Patent Document 1 is a melt-blown nonwoven fabric electretized by applying a high pressure. Generally, a fine sheet such as a melt-blown nonwoven sheet is included per unit volume as compared with a thick sheet. Since the total surface area of the fiber is large and a larger charging effect can be obtained, the collection performance can be further improved, and the fiber can be used for applications that place more importance on high collection.

  On the other hand, an attempt has been made to apply this charging technology to a thick sheet to add high collection performance to the original low pressure loss characteristics.

  For example, a charged filter medium characterized by comprising a blend of polyester fiber and polypropylene fiber has been proposed (Patent Document 2). This charged filter medium is a short fiber nonwoven fabric, and relates to a frictionally charged nonwoven fabric in which one fiber is positively charged and one fiber is negatively charged in accordance with a charge train when two different types of fibers are rubbed with each other. However, in this patent document, the relationship between the collection performance and the pressure loss is unclear, and before carrying out tribocharging, it is necessary to wash and remove additives such as lubricants and antistatic agents that adhere to the fibers that prevent charging. There are many processes compared with other nonwoven fabric processes, and it is disadvantageous in terms of production cost.

As a method for obtaining a sheet having a relatively large fineness more easily than a short fiber nonwoven fabric, there is a spunbond method, and studies have been made to charge a nonwoven fabric obtained by the spunbond method.
For example, the applicant previously described a nonwoven fabric composed of a core-sheath type composite fiber in which the core component is a polyester resin and the sheath component is a polyolefin resin, and the nonwoven fabric is an electret processed nonwoven fabric. Proposed (Japanese Patent Application No. 2006-342268).
However, the non-woven fabric proposed here is a spunbonded non-woven fabric. By using polyolefin as the sheath and polyester as the core, it is possible to provide a sheet with excellent electret characteristics, rigidity, and dimensional stability. Was clear, but the electret characteristics and collection performance were not clear.

As described above, in a thick sheet with an emphasis on low pressure loss characteristics, attempts to add high collection performance have been made, but a sufficient level has not been obtained.
JP-A 61-289177 Special table 2003-512147 gazette

  An object of the present invention is to provide a spunbonded nonwoven fabric that has low pressure loss and excellent collection performance, particularly a spunbonded nonwoven fabric that can be suitably used for an air filter, in view of the above-described conventional technology.

  Another object of the present invention is to provide an air filter that uses the spunbonded nonwoven fabric and has low pressure loss and excellent collection performance.

  The electret fiber sheet of the present invention that solves this problem has the following configuration (1).

(1) A spunbonded nonwoven fabric mainly comprising nonconductive fibers, wherein the nonconductive fibers are charged, the pressure loss at a wind speed of 6.5 m / min is 9 Pa or less, and the diameter is 0.3 to 0.5 μm. The particle collection efficiency is 80% or more, and the QF value is 0.35 Pa ⁻¹ or more.
A more specifically preferred embodiment of such a spunbonded nonwoven fabric has one of the following configurations (2) to (7) .

(2) The spunbonded nonwoven fabric according to (1), wherein the spunbonded nonwoven fabric contains 0.1 to 5% by weight of a hindered amine compound.

（ここで、Ｒ₁ 〜Ｒ₃ は水素または炭素原子数１〜２のアルキル基、Ｒ₄ は水素または炭素数１〜６のアルキル基である） (3) the hindered amine spunbonded nonwoven fabric according to (2) the compound is characterized by having a structure represented by the following general formula (1).

(Where R _{1 to} R ₃ are hydrogen or an alkyl group having 1 to 2 carbon atoms, and R ₄ is hydrogen or an alkyl group having 1 to 6 carbon atoms)

(4) The spunbonded nonwoven fabric according to (3) above, wherein the compound having the structure represented by the general formula (1) is a compound having a structure represented by the following general formula (2) .

(5) The spunbonded nonwoven fabric according to any one of (1) to (4) , wherein the nonconductive fiber is a polyolefin fiber.

(6) The spunbonded nonwoven fabric according to (5) , wherein the polyolefin fiber is mainly composed of polypropylene.

(7) An air filter comprising the spunbonded nonwoven fabric according to any one of (1) to (6) .

  According to the present invention, it is possible to provide an excellent spunbonded nonwoven fabric having low pressure loss and high collection performance.

  If such a spunbond nonwoven fabric is used as a filter medium for an air filter, a high-performance air filter capable of exhibiting high collection and low pressure loss can be provided.

The spunbonded nonwoven fabric of the present invention is a spunbonded nonwoven fabric mainly comprising nonconductive fibers, the nonconductive fibers are charged, the pressure loss at a wind speed of 6.5 m / min is 9 Pa or less, the diameter is 0.00. It is characterized in that the collection efficiency of 3-0.5 μm particles is 80% or more and the QF value is 0.35 Pa ⁻¹ or more.

  The spunbond nonwoven fabric according to the present invention extrudes a molten polymer from a nozzle, sucks and stretches the polymer with a high-speed suction gas, collects fibers on a moving conveyor to form a web, and further continuously heat bonds, entangles, etc. It is possible to manufacture by a so-called spunbond method in which the sheet is integrated into a sheet.

  For the spunbond nonwoven fabric of the present invention, the existing bonding and entanglement methods such as thermal bonding using a binder, thermal embossing bonding, ultrasonic embossing bonding, thermal calender bonding, needle punch entanglement, water jet entanglement can be used as the bonding method. However, needle punch entanglement or water jet entanglement in which the surface area of the fibers constituting the sheet is effectively utilized and there are many voids between the internal fibers of the sheet is particularly preferable.

The nonconductive fiber referred to in the present invention is not particularly limited as long as it mainly contains fibers made of a nonconductive polymer. The non-conductivity here has a volume resistivity of preferably 10 ¹² · Ω · cm or more, and more preferably 10 ¹⁴ · Ω · cm or more. Volume resistivity is measured according to ASTM D257. When a non-woven fabric comprising such fibers is charged, a large amount of charge can be retained, and as a result, the collection performance can be improved.

  Examples of such nonconductive materials include polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyesters such as polylactic acid, polycarbonate, polystyrene, polyphenylene sulfide, fluorine-based resins, and These copolymers or mixtures can be mentioned. Among these materials, those mainly composed of polyolefin are preferable from the viewpoint of exhibiting electret performance. Further, other components may be copolymerized as long as the properties of the polymer are not impaired. Among polyolefins, polypropylene is more preferable because it is excellent in heat resistance. Further, the non-conductive fiber referred to in the present invention may be two or more kinds of mixed fibers composed of these materials.

  In addition, the non-conductive fiber referred to in the present invention is not particularly limited, such as a single component fiber, a composite component type fiber such as a core-sheath type or a sea-island type. Then, since there is a possibility that electric charge leaks due to a difference in electrical resistance between resins, it is desirable to use a single component fiber.

  Furthermore, it is important that the spunbond nonwoven fabric of the present invention is charged. By using a charged spunbond nonwoven fabric, it is possible to obtain high collection performance while maintaining low pressure loss characteristics due to the electrostatic adsorption effect. It can be done.

  In producing a charged spunbonded nonwoven fabric, the charging method is not particularly limited, but according to the various knowledge of the present inventors, in particular, the corona charging method is charged by drying after applying water to the nonwoven fabric sheet. (E.g., the method described in JP-A-9-501604, JP-A-2002-249978, etc.), the thermal electret method, and the like are preferably used. In the case of the corona charging method, an electric field strength of preferably 15 kV / cm or more, more preferably 20 kV / cm or more is suitable. In addition, the charging process may be performed continuously during the production of the nonwoven fabric, or the produced nonwoven fabric may be wound once and processed in a separate step.

Also, spunbonded nonwoven fabric of the present invention, first, the pressure loss 9Pa less in wind speed 6.5m / min, more than 70% trapping efficiency of particles with a diameter of 0.3 to 0.5 [mu] m, QF value 0.25Pa ^-1 or more, and more than that, the trapping efficiency of particles having a pressure loss of 9 Pa or less and a diameter of 0.3 to 0.5 μm at a wind speed of 6.5 m / min is 80% or more. The spunbonded nonwoven fabric of the present invention is characterized by a QF value of 0.35 Pa ⁻¹ or more.
Incidentally, the pressure loss at the aforementioned wind speed of 6.5 m / min is 9 Pa or less, the collection efficiency of particles having a diameter of 0.3 to 0.5 μm is 70% or more, and the QF value is 0.25 Pa ⁻¹ or more. For the sake of convenience, a material having a level that does not satisfy the above-described collection efficiency and QF value of the present invention may be referred to as a “reference example” spunbond nonwoven fabric.

  Here, the pressure loss and the collection performance in the present invention are measured by the following measuring method or a measuring method capable of obtaining the same result. That is, five 15 cm × 15 cm measurement samples are collected from an arbitrary portion of the nonwoven fabric, and the collection performance and pressure loss of each sample are measured with the collection performance measuring apparatus schematically shown in FIG.

This collection performance measuring apparatus has a configuration in which a dust storage box 2 is connected to the upstream side of a sample holder 1 for setting a measurement sample M, and a flow meter 3, a flow rate adjusting valve 4 and a blower 5 are connected to the downstream side. Yes. In addition, the particle counter 6 is used for the sample holder 1, and the number of dusts on the upstream side and the number of dusts on the downstream side of the measurement sample M can be measured via the switching cock 7. Furthermore, the sample holder 1 includes a pressure gauge 8 and can read the static pressure difference between the upstream and downstream of the sample M. In measuring the collection performance, a solution containing polystyrene particles having a diameter of 0.3 to 0.5 μm (for example, a 0.309 U polystyrene 10 wt% solution manufactured by Nacalai Tech) is diluted with distilled water (for example, Nacalai Tech 0 In the case of 309U, it is diluted up to 200 times) and filled in the dust storage box 2. Next, the sample M is set in the holder 1, the air volume is adjusted with the flow rate adjusting valve 4 so that the filter passing speed is 6.5 m / min, and the dust concentration is 20,000 to 40,000 pieces / 2.83 × 10 ^{−. 4} m ³ (0.01 ft ³ ), the number of dusts D upstream of the sample M and the number of dusts d downstream of the sample M are set to a particle size of 0. 0 with a particle counter 6 (for example, KC-01D manufactured by Rion Co., Ltd.). Each sample is measured five times in the range of 3 to 0.5 μm, and the collection performance (%) of each sample is obtained by the following calculation formula.
Collection performance of each sample (%) = [1- (D1 / D2)] × 100
Here, D1: number of dusts downstream (total of 5 times)
D2: Number of upstream dust (total of 5 times)
The final collection performance (%) is obtained by rounding off the third decimal place of the average value of 5 samples.

  In addition, since the number of downstream dusts decreases as the non-collected nonwoven fabric increases, the value of the collection performance increases.

  The pressure loss (Pa) is calculated by reading the difference in static pressure between the upstream and downstream of the sample M at the time of collecting performance measurement with a pressure gauge 8 and rounding off the first decimal place of the average value of 5 samples. is there.

Further, there is a QF value as an index of filtration performance, which is obtained by calculating the following formula using the collection performance and pressure loss, and rounding off the third decimal place.
QF value (Pa ⁻¹ ) = − [ln (1- [collecting performance (%)] / 100)] / [pressure loss (Pa)]

From the above equation, the QF value can be said to indicate the collection performance per unit pressure loss, and the higher the QF value, the better the filtration performance. Here, when the QF value shows a high value, the following two cases can be considered. That is, a case where the collection performance shows a relatively high value and a case where the pressure loss shows a relatively low value. In the present invention, in consideration of these two cases, in addition to the QF value range (0.25 Pa ⁻¹ or more) showing excellent filtration performance, the highest pressure loss line when the collection performance shows a relatively high value. Is set to 9 Pa, and the minimum line of the collection performance when the pressure loss shows a relatively low value is set to 70% (however, this is the level of the above-mentioned “reference example”) . That is, it is important that the pressure loss, the collection performance and the QF value satisfy the above-mentioned range at the same time. If any one of these three characteristics is out of the range, the low pressure loss and the high collection rate It means that it is not a high-performance spunbonded nonwoven fabric that exhibits performance at the same time.

In addition, the spunbonded nonwoven fabric of the present invention further has a pressure loss of 9 Pa or less at a wind speed of 6.5 m / min, a collection efficiency of particles having a diameter of 0.3 to 0.5 μm of 80% or more, and a QF value. It shows the physical property of 0.35 Pa ⁻¹ or more , which indicates that it has a high collection performance with a low pressure loss. The spunbond of the present invention satisfies these characteristics. This is a characteristic of nonwoven fabric.

In addition, the spunbonded nonwoven fabric of the present invention preferably contains 0.1% by weight or more of a hindered amine compound, and 0.3% by weight or more from the viewpoint of improving the charging performance of the fiber and improving the weather resistance. It is more preferable that the content is 0.5% by weight or more. The content is preferably 5.0% by weight or less, more preferably 4.0% by weight or less, and particularly preferably 3.0% by weight or less. The content of the compound here is determined as follows.

After Soxhlet extraction of 2 g of nonwoven fabric with chloroform, HPLC fractionation is repeated for the extract, and the structure of each fraction is confirmed by ¹ H-NMR measurement. The weights of the fractions containing the compound are totaled to determine the ratio to the whole nonwoven fabric, and this is defined as the compound content.

  If the content of the hindered amine compound is 0.1% by weight or more, an effect of improving the charging performance of the fiber can be obtained. However, if the content of the hindered amine compound exceeds 5.0% by weight, the spinnability deteriorates when the nonwoven fabric is produced, and the productivity tends to be inferior.

  Such hindered amine compounds include poly [(6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl) ((2,2,6,6 -Tetramethyl-4-piperidyl) imino) hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino)] (manufactured by Ciba Japan, Kimasorb (registered trademark) 944LD), dimethyl succinate- 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (manufactured by Ciba Japan, Tinuvin (registered trademark) 622LD), 2- (3,5-di- t-Butyl-4-hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl) (manufactured by Ciba Japan, Tinuvin (registered trademark) 14) ), And the like.

Among these, a hindered amine compound having a structure represented by the following general formula (1) is preferable in terms of improving the charging performance of the fiber.

As described above, the filter performance is surprisingly improved by making the spunbond nonwoven fabric composed of the fibers containing the hindered amine compound having a specific structure charged. That is, by including a hindered amine compound having a specific structure, the pressure loss at a wind speed of 6.5 m / min is 9 Pa or less, the collection efficiency of particles having a diameter of 0.3 to 0.5 μm is 70% or more, and the QF value. Can produce a spunbonded nonwoven fabric having a low pressure loss and a high collection efficiency (the level of the reference example) of 0.25 Pa ⁻¹ or more.

Such a compound is not particularly limited as long as it is a compound having the structure described above. Among R _{1 to} R _{4 in} the general formula (1), R _{1 to} R ₃ are hydrogen and R ₄ is carbon. A compound having a structure which is an alkyl group of formula 4, particularly an n-butyl group, is particularly preferred. That is, it is a compound having a structure represented by the following general formula (2), and the compound B used in Example 1 and Example 2 described later is preferable for obtaining the spunbonded nonwoven fabric of the present invention .

  In addition, the compound which has a structure represented by General formula (1) may be 1 type, or may be a mixture of multiple types.

  By allowing the compound to be present in the spunbond nonwoven fabric, the charge imparted by charging can be more effectively stabilized. Therefore, when the spunbond nonwoven fabric is used as a filter medium for air filters, the collection performance is improved. Thus, an air filter having a high collection performance with a low pressure loss can be realized.

  The spunbonded nonwoven fabric of the present invention contains a non-conductive polymer containing the above-mentioned compound. In addition to the above-mentioned compound, the polymer contains an antioxidant, a light stabilizer, a heat stabilizer, etc. The stabilizer normally contained in the resin material may be included.

  The average fiber diameter of the fibers constituting the spunbonded nonwoven fabric of the present invention is not particularly limited as long as the obtained spunbonded nonwoven fabric is suitable for filter applications, but is preferably 5 μm or more, more preferably 10 μm or more. Moreover, 30 micrometers or less are preferable and 25 micrometers or less are more preferable. When the average fiber diameter is smaller than 5 μm, the pressure loss of the spunbonded nonwoven fabric tends to increase, which is not preferable. On the other hand, when the average fiber diameter is larger than 30 μm, the fiber surface area per unit amount of the spunbonded nonwoven fabric is too small, and the collection performance of the spunbonded nonwoven fabric tends to be lowered, which is not preferable. In addition, the average fiber diameter here is 10 pieces of small sample taken at random from the spunbond nonwoven fabric, photographed 500 to 3000 times with a scanning electron microscope or the like, 10 pieces from each sample, 100 pieces in total. The fiber diameter is measured and the average value is calculated by rounding off the first decimal place.

  Furthermore, the cross-sectional shape of the fibers constituting the spunbonded nonwoven fabric of the present invention is not particularly limited as long as the obtained spunbonded nonwoven fabric is suitable for filter applications, but it is not limited to a circular shape, a hollow circular shape, an elliptical shape, a flat shape, or An irregular shape such as X-type and Y-type, a polygonal shape, a multi-leaf shape, and the like are preferable forms. The fiber diameter of the non-circular fiber is obtained by taking a circumscribed circle and an inscribed circle with respect to the fiber cross section, and obtaining an average value of the respective diameters as the fiber diameter.

Further, the basis weight of the spunbonded nonwoven fabric of the present invention is not particularly limited as long as it is suitable for filter applications, but it is preferably 20 g / m ² or more, more preferably 40 g / m ² or more. 60 g / m ² or more is particularly preferable. Further, it is preferably 300 g / m ² or less, more preferably 250 g / m ² or less, and particularly preferably 200 g / m ² or less. When the basis weight is less than 20 g / m ² , the strength and rigidity of the nonwoven fabric may be insufficient, which is not preferable. On the other hand, when the weight per unit area exceeds 300 g / m ² , the pressure loss tends to decrease, which is not preferable in terms of cost. According to JIS L 1906 (2000 edition) 5.2, the basis weight here is a value obtained by measuring three samples each having a length of 50 cm and a width of 50 cm and measuring the weight of each sample. The average value is calculated per unit area and rounded to the first decimal place.

  Furthermore, the spunbond nonwoven fabric of the present invention may be laminated with other sheets to form a laminated fiber sheet. For example, it is preferable to use a spunbonded nonwoven fabric and a sheet having higher rigidity than the laminated sheet to improve product strength, or to use in combination with a sheet having functionalities such as deodorization and antibacterial properties.

  Although the manufacturing method of the spun bond nonwoven fabric of this invention is not specifically limited, For example, it can manufacture with the following method.

First, a resin material is prepared, and a spunbonded nonwoven fabric is obtained by the spunbond method described above. When a compound such as a hindered amine compound is contained in the spunbond nonwoven fabric, the resin material and the compound are kneaded in advance. As a method of kneading the resin material and the compound, they are mixed and supplied to an extruder hopper of a spinning machine, kneaded in the extruder, and directly fed to the die, or the compound and the resin material are kneaded in advance. There is a method in which a master chip is prepared by kneading with an extruder or a static kneader, and this is melted in the extruder and supplied to the die part.
Next, the spunbonded nonwoven fabric is subjected to charging treatment to obtain a charged spunbonded nonwoven fabric. The charging treatment may be performed on a spunbond nonwoven fabric single layer or a laminated fiber sheet laminated with other sheets. In particular, the nonconductive fiber is charged, the pressure loss at a wind speed of 6.5 m / min is 9 Pa or less, the collection efficiency of particles having a diameter of 0.3 to 0.5 μm is 70% or more, and the QF value is 0.25 Pa ^−1. In order to obtain the above spunbonded nonwoven fabric (level of reference example) , the hindered amine compound is contained in an amount of 0.1 to 5% by weight, and the hindered compound has a structure represented by the following general formula (1). it is effective.

Furthermore, in order to obtain a spunbonded nonwoven fabric in which the collection efficiency of particles having a diameter of 0.3 to 0.5 μm at a wind speed of 6.5 m / min according to the present invention is 80% or more and the QF value is 0.35 Pa ⁻¹ or more. In particular, it is important that the compound having the structure represented by the general formula (1) is a compound having a structure represented by the following general formula (2).

  Since the use of the spunbond nonwoven fabric of the present invention is excellent in dust collection performance, it can be used as a filter medium. The filter medium is suitable for high-performance applications such as air filters in general, air conditioning filters, air cleaner filters, automobile cabin filters, vacuum cleaner filters, mask filters, but the application range is limited to these. It is not a thing.

Hereinafter, the present invention will be described more specifically with reference to Examples , Reference Examples and Comparative Examples . In addition, each characteristic value of the above-mentioned spunbonded nonwoven fabric, and each characteristic value in the following examples etc. are measured by the following method.

(1) Weight per unit (g / m ² )
In accordance with JIS L 1906 (2000 version) 5.2, three samples of 50 cm in the vertical direction and 50 cm in the horizontal direction were collected, and the weight of each sample was measured. Rounded down to the nearest decimal place.

(2) Average fiber diameter (μm)
Ten small sample pieces were randomly collected from the spunbond nonwoven fabric, photographed with a scanning electron microscope at a magnification of 500 to 3000 times, 10 from each sample, and a total of 100 fiber diameters were measured in μm units. The value was calculated by rounding off the first decimal place.

(3) Collection performance (%), pressure loss (Pa), QF value (Pa ⁻¹ )
The dust collection performance was measured by the following method.

Five samples of 15 cm × 15 cm were taken from any part of the spunbonded nonwoven fabric, and the collection performance of each sample was measured with the collection performance measuring apparatus shown in FIG. This collection performance measuring apparatus has a configuration in which a dust storage box 2 is connected to the upstream side of a sample holder 1 for setting a measurement sample M, and a flow meter 3, a flow rate adjusting valve 4 and a blower 5 are connected to the downstream side. Yes. Further, the particle counter 6 is connected to the sample holder 1, and the number of dusts on the upstream side and the number of dusts on the downstream side of the measurement sample M can be measured via the switching cock 7. In measuring the collection efficiency, a 10% by weight polystyrene 0.309U solution (manufactured by Nacalai Tech) is diluted 200 times with distilled water and filled in the dust storage box 2. Next, the sample M is set in the holder 1, and the air volume is adjusted by the flow rate adjusting valve 4 so that the filter passing speed is 6.5 m / min, and the dust concentration is 20,000 to 40,000 pieces / (2.83 × 10 8). ⁻⁴ m ³ (0.01 ft ³ )), the dust number D2 upstream of the sample M and the dust number D1 downstream are sampled by a particle counter 6 (manufactured by Lion Co., Ltd., KC-01D) with a dust particle size of 0.1. Each sample was measured 10 times in the range of 3 to 0.5 μm, and the collection performance (%) of each sample was determined by the following calculation formula.
Collection performance of each sample (%) = [1- (D1 / D2)] × 100
Here, D1: number of dusts downstream (total of 5 times)
D2: Number of upstream dust (total of 5 times)
The final collection performance (%) was obtained by rounding off the third decimal place of the average value of 5 samples.

  Further, the pressure loss (Pa) was calculated by reading the static pressure difference between the upstream and downstream of the sample M during the collection performance measurement with the pressure gauge 8 and rounding off the first decimal place of the average value of the five samples.

Furthermore, QF value is the following equation using the value of collection performance and pressure loss obtained by the above method,
QF value (Pa ⁻¹ ) = − [ln (1- [collecting performance (%)] / 100)] / [pressure loss (Pa)]
Calculated by rounding off the third decimal place.

得られたスパンボンド不織布に、コロナ荷電法により２５ｋＶ／ｃｍの印加電圧で帯電処理を実施し、帯電スパンボンド不織布を得た。この帯電スパンボンド不織布の特性値を測定し、表１に示した。 Reference example 1
MFR30, melting point 170, to which 1.0% by weight of Kimasorb (registered trademark) 944 (manufactured by Ciba Japan, having a structure represented by the following general formula (3), hereinafter abbreviated as compound A) was added. Polypropylene resin at 0 ° C. was spun from the pores at a die temperature of 300 ° C. by the spunbond method, and then spun at a spinning speed of 4400 m / min by an ejector and collected as a fiber web on a moving net conveyor. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 14 μm and a basis weight of 70 g / m ² .

The obtained spunbonded nonwoven fabric was charged with an applied voltage of 25 kV / cm by a corona charging method to obtain a charged spunbonded nonwoven fabric. The characteristic values of this charged spunbond nonwoven fabric were measured and shown in Table 1.

Reference example 2
The polypropylene resin used in Reference Example 1 was spun from the pores at a die temperature of 300 ° C. by the spunbond method, then spun at a spinning speed of 4000 m / min by an ejector, and collected as a fiber web on a moving net conveyor. did. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 20 μm and a basis weight of 100 g / m ² .
While running the obtained spunbond nonwoven fabric along the water surface of the water tank to which the reverse osmosis membrane filtered water is supplied, the surface is infiltrated by abutting a slit-like suction nozzle to suck the water, A charged spunbonded nonwoven fabric was obtained by drying with hot air at 80 ° C. for 20 minutes after draining. The characteristic values of this charged spunbond nonwoven fabric were measured and shown in Table 1.

得られたスパンボンド不織布を参考例１と同様の方法で帯電処理した後、特性値を測定し、表１に示した。 Example 1
MFR30 having a melting point of 1.0% by weight of Kimasorb (registered trademark) 2020 (manufactured by Ciba Japan, having a structure represented by the following general formula (4), hereinafter abbreviated as compound B), melting point A polypropylene resin at 170 ° C. was spun from the pores at a die temperature of 300 ° C. by the spunbond method, and then spun at a spinning speed of 4000 m / min by an ejector and collected as a fiber web on a moving net conveyor. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 14 μm and a basis weight of 70 g / m ² .

The obtained spunbonded nonwoven fabric was charged in the same manner as in Reference Example 1, and then the characteristic values were measured and shown in Table 1.

Example 2
The polypropylene resin used in Example 1 was spun from the pores at a die temperature of 300 ° C. by the spunbond method, and then spun at a spinning speed of 4000 m / min by an ejector and collected as a fiber web on a moving net conveyor. did. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 20 μm and a basis weight of 100 g / m ² .
The obtained spunbonded nonwoven fabric was charged in the same manner as in Reference Example 2, and then the characteristic values were measured and shown in Table 1.

Comparative Example 1
The same polypropylene resin as that used in Reference Example 1 except that it does not contain compound A was spun from the pores at a die temperature of 300 ° C. by the spunbond method, and then spun at a spinning speed of 4400 m / min by an ejector. Was collected as a fiber web on a net conveyor. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 14 μm and a basis weight of 70 g / m ² .
The obtained spunbonded nonwoven fabric was charged in the same manner as in Reference Example 1, and then the characteristic values were measured and shown in Table 1.

Comparative Example 2
The polypropylene resin used in Comparative Example 1 was spun from the pores at a die temperature of 300 ° C. by the spunbond method, then spun at a spinning speed of 4000 m / min by an ejector, and collected as a fiber web on a moving net conveyor. did. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 20 μm and a basis weight of 100 g / m ² .
The obtained spunbonded nonwoven fabric was charged in the same manner as in Reference Example 2, and then the characteristic values were measured and shown in Table 1.

Comparative Example 3
The polypropylene resin used in Comparative Example 1 was spun from the pores at a die temperature of 300 ° C. by the spunbond method, then spun at a spinning speed of 4000 m / min by an ejector, and collected as a fiber web on a moving net conveyor. did. The collected fiber web was needle punched to obtain a spunbonded nonwoven fabric having an average fiber diameter of 20 μm and a basis weight of 120 g / m ² .
The obtained spunbonded nonwoven fabric was charged in the same manner as in Reference Example 2, and then the characteristic values were measured and shown in Table 1.

Comparative Example 4
MFR800 added with 1.0% by weight of compound A, polypropylene resin having a melting point of 170 ° C., melt discharge method, a nozzle having a diameter of 0.4 mm, a polymer discharge rate of 40 g / min, a nozzle temperature of 280 ° C., an air pressure of 0 The melt blown nonwoven fabric having an average fiber diameter of 5 μm and a weight per unit area of 20 g / m ² was obtained by spraying under a condition of 0.04 MPa and collecting on a moving net conveyor.
The obtained meltblown nonwoven fabric was electret-treated in the same manner as in Reference Example 2, and then the characteristic values were measured and shown in Table 1.

Comparative Example 5
MFR800 added with 1.0% by weight of compound B, polypropylene resin having a melting point of 170 ° C., melt blow method, a nozzle having a diameter of 0.4 mm, a polymer discharge rate of 40 g / min, a nozzle temperature of 280 ° C., an air pressure of 0 The melt-blown nonwoven fabric having an average fiber diameter of 3 μm and a basis weight of 30 g / m ² was obtained by spraying under a condition of 0.06 MPa and collecting on a moving net conveyor.
The obtained meltblown nonwoven fabric was electret-treated in the same manner as in Reference Example 2, and then the characteristic values were measured and shown in Table 1.

Examples 1-2 and Reference Examples 1-2 produced by a spunbond method using a polypropylene resin containing a hindered amine compound show high collection performance while having a low pressure loss, and have a high QF value. showed that. In particular, in Examples 1 and 2 containing the compound B having the structure represented by the general formula (4) among the hindered amine compounds, the effect was remarkable.

  On the other hand, for Comparative Examples 1 to 3 manufactured by the spunbond method using a polypropylene resin not containing a hindered amine compound, the pressure loss was low in Comparative Example 1, but the collection performance and QF value were low. In Comparative Example 2, the pressure loss was low and the collection performance was high, but the QF value was low, and in Comparative Example 3, the collection performance was high, but the pressure loss was high, and QF The value was also low, and none of them was a spunbonded nonwoven fabric satisfying low pressure loss and high collection performance.

  Moreover, about the comparative examples 3 and 4 manufactured by the melt blow method using the polypropylene resin containing the hindered amine compound, the pressure loss was low in Comparative Example 3, but the collection performance and the QF value were low. In Comparative Example 4, the collection performance showed a high value, but the pressure loss was high and the QF value was low, and it was not suitable as a nonwoven fabric satisfying the high collection performance with a low pressure loss.

  As described above, the spunbonded nonwoven fabric of the present invention is a high-performance spunbonded nonwoven fabric that simultaneously satisfies the two contradictory properties that are excellent in low pressure loss characteristics and have high collection performance.

  According to the present invention, a high-performance spunbond having a low pressure loss and high collection performance can be obtained, and this spunbond nonwoven fabric can be preferably used as an air filter as a filter medium, but its application range is not limited to these. Absent.

FIG. 1 is a schematic diagram showing a measuring device for collecting performance and pressure loss.

Explanation of symbols

1 Holder 2 Dust Storage Box 3 Flowmeter 4 Flow Control Valve 5 Blower 6 Particle Counter 7 Switching Cock 8 Pressure Gauge M Measurement Sample

Claims (7)

A spunbonded nonwoven fabric mainly comprising non-conductive fibers, wherein the non-conductive fibers are charged, and the pressure loss at a wind speed of 6.5 m / min is 9 Pa or less and the diameter is 0.3 to 0.5 μm. A spunbonded nonwoven fabric having a collection efficiency of 80% or more and a QF value of 0.35 Pa- ¹ or more.   The spunbonded nonwoven fabric according to claim 1, wherein the spunbonded nonwoven fabric contains 0.1 to 5% by weight of a hindered amine compound. Spunbonded nonwoven fabric according to claim 2, characterized by having a structure wherein the hindered amine compound is represented by the following general formula (1).

(Where R _{1 to} R ₃ are hydrogen or an alkyl group having 1 to 2 carbon atoms, and R ₄ is hydrogen or an alkyl group having 1 to 6 carbon atoms) Compounds having the structure represented by the general formula (1) is, spunbonded nonwoven fabric according to claim 3, characterized in that a compound having a structure represented by the following general formula (2).

The spunbonded nonwoven fabric according to any one of claims 1 to 4 , wherein the non-conductive fibers are polyolefin fibers. The spunbonded nonwoven fabric according to claim 5 , wherein the polyolefin fiber is mainly composed of polypropylene. It is comprised with the spun bond nonwoven fabric in any one of Claims 1-6 , The air filter characterized by the above-mentioned.

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