WO2021153296A1

WO2021153296A1 - Layered electret nonwoven fabric, and air filter unit and air purifier using same

Info

Publication number: WO2021153296A1
Application number: PCT/JP2021/001409
Authority: WO
Inventors: 山野浩司; 小出現
Original assignee: 東レ株式会社
Priority date: 2020-01-27
Filing date: 2021-01-18
Publication date: 2021-08-05
Also published as: TW202146730A; KR20220124188A; CN114981494A; JPWO2021153296A1

Abstract

A goal of the present invention is to provide: a layered electret nonwoven fabric that has low pressure loss and high trapping efficiency, as well as superior moldability into filter form; and an air filter unit and an air purifier that use said layered electret nonwoven fabric.　A layered electret nonwoven fabric according to the present invention is such that a spunbond nonwoven fabric layer constituted of fibers formed from a polyolefin resin (A), and a melt-blown nonwoven fabric layer constituted of fibers formed from a polyolefin resin (B), are layered. The layered electret nonwoven fabric contains 0.1–5% by mass of a hindered amine compound. The fabric weight of the layered electret nonwoven fabric is 5–60 g/m². The melt-blown nonwoven fabric layer constitutes 1–15% by mass of the mass of the layered electret nonwoven fabric.

Description

Laminated electret non-woven fabric, air filter unit using this, air purifier

The present invention comprises a laminated electret non-woven fabric, which is composed of fibers formed of a polyolefin resin, is lightweight and has excellent flexibility, has high collection efficiency with low pressure loss, and is excellent in filter workability, and the laminated electret. Regarding an air filter composed of non-woven fabric.

Conventionally, an air filter has been used to remove pollen, dust, etc. in gas, and a fiber sheet is often used as a filter medium. The performance required for the air filter is that it can collect a large amount of microscopic dust (high collection performance) and that there is little resistance when gas passes through the inside of the air filter (low pressure loss). be.

Melt blown non-woven fabrics with an average fiber of 15 μm or less are often used for these air filter materials in order to form a dense matrix. The shape used is a cup shape or a pleated shape.

On the other hand, since the melt blown non-woven fabric has low strength, a packing material or a reinforcing material was required when it was used as an air filter material. Patent Document 1 proposes an air filter in which a melt-blown non-woven fabric and a spunbonded non-woven fabric are laminated. By appropriately controlling the surface structure and breathability of the laminated non-woven fabric, it is possible to improve the mechanical collection performance of the laminated non-woven fabric, and further, the high level of durability and flexibility that the laminated non-woven fabric aims at. , It is possible to have workability.

By the way, there is known a technique for improving the collection performance by charging the fiber sheet and utilizing the electrostatic action in addition to the physical action. Patent Document 2 proposes a laminated electret non-woven fabric in which a melt-blown non-woven fabric and a spunbonded non-woven fabric are laminated to form an electret. This is because the fibers that make up the melt-blown non-woven fabric are a mixture of two types of fibers with different melting points, so that when laminated with spunbonded non-woven fabric and embossed rolls, the fused portion can be reduced and the pressure loss can be reduced. It is possible.

Japanese Patent Application Laid-Open No. 2019-151962 International Publication No. 2011/004696

However, in the laminated non-woven fabric as in Patent Document 1, since the electrical collection effect does not work, the collection efficiency is low and the collection performance is low. Further, in the laminated electret non-woven fabric as in Patent Document 2, since it is necessary to increase the grain size and the melt blow content of the laminated electret non-woven fabric in order to obtain high collection efficiency, the flexibility is lowered and the bleeds have a mountain shape during filter molding. Is rounded, and an increase in structural pressure loss as a filter is an issue.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to have low pressure loss, high collection efficiency, and excellent ease of molding into a filter shape. It is an object of the present invention to provide a laminated electret non-woven fabric, an air filter unit using the laminated electret non-woven fabric, and an air purifier.

As a result of diligent studies to solve the problems of the prior art, the present inventors have made one layer of a spunbonded nonwoven fabric formed of a polyolefin-based resin on at least one surface of the melt-blown nonwoven fabric formed of a polyolefin-based resin. Alternatively, by using a structure in which multiple layers are laminated, the texture is within a specific range, the content of the melt blown non-woven fabric is within a specific range, and the electlet processing is performed, the pressure loss is reduced and the collection efficiency is increased. In addition, because of its excellent flexibility, it is easy to mold into a filter, and the peaks of the peaks that occur when folded during molding become sharp (sharp angles), and the increase in structural pressure loss can be suppressed. It has been found that it is possible to obtain a non-woven fabric. Furthermore, it has been found that this laminated electret non-woven fabric is suitably used for an air filter unit and an air purifier incorporating the air filter unit.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.

The laminated electret nonwoven fabric of the present invention includes a spunbonded nonwoven fabric layer composed of fibers formed of a polyolefin resin (A) and a melt blow nonwoven fabric layer composed of fibers formed of a polyolefin resin (B). The laminated electret non-woven fabric is a laminated electlet non-woven fabric, which contains 0.1 to 5% by mass of a hindered amine compound, and the texture of the laminated electlet non-woven fabric is 5 to 80 g / m ² . Further, the content of the melt-blown non-woven fabric layer is 1 to 50% by mass with respect to the mass of the laminated electlet non-woven fabric.

According to a preferred embodiment of the laminated electret non-woven fabric of the present invention, the texture of the laminated electret non-woven fabric is 5 to 60 g / m ² , and the content of the melt-blown non-woven fabric layer is relative to the mass of the laminated electret non-woven fabric. It is 1 to 15% by mass.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the laminated electret nonwoven fabric contains a crystal nucleating agent.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, 0.001 to 1% by mass of the nucleating agent of the crystal is contained in the laminated electret nonwoven fabric.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the average single fiber diameter of the fibers constituting the spunbonded nonwoven fabric layer is 6.5 to 22 μm.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the hindered amine compound is a compound represented by the following general formula (1).

(Here, 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).

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the melt flow rate (MFR) of the fiber formed from the polyolefin resin (A) is 32 to 850 g / 10 minutes.

According to a preferred embodiment of the laminated electret non-woven fabric of the present invention, the ratio of the MFR of the polyolefin-based resin (A) to the polyolefin-based resin (B) (MFR _B / MFR _A ) is 1 to 13.

According to a preferred embodiment of the laminated electret non-woven fabric of the present invention, the thickness of the laminated electret non-woven fabric is 0.05 to 1 mm.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the longitudinal tensile strength per unit basis weight is 0.3 (N / 5 cm) / (g / m ² ) or more.

According to a preferred embodiment of the laminated electret nonwoven fabric of the present invention, the pressure loss per unit is 0.1 to 0.5 (Pa) / (g / m ² ).

The air filter unit of the present invention uses the above-mentioned laminated electret non-woven fabric as a filter medium, and a pleated joint formed of the filter medium and a reinforcing material is gripped by a fixing material.

Further, the air purifier of the present invention incorporates the above-mentioned air filter unit.

According to the laminated electret non-woven fabric of the present invention, the laminated electret non-woven fabric exhibiting high collection performance with low pressure loss can be obtained by the above configuration, and further, the laminated electret non-woven fabric has a workability and a filter shape. An air filter unit and an air purifier having excellent moldability and excellent collection performance can be obtained.

FIG. 1 is a schematic side view showing a collection efficiency and pressure loss measuring device.

The laminated electret nonwoven fabric of the present invention includes a spunbonded nonwoven fabric layer composed of fibers formed of a polyolefin resin (A) and a melt blow nonwoven fabric layer composed of fibers formed of a polyolefin resin (B). there are laminated, a laminated electret nonwoven, a hindered amine compound is 0.1 to 5 mass%, the mass per unit area of the laminated electret nonwoven fabric, a 5 ~ 80g / m ^2, containing the meltblown nonwoven fabric layer The amount is 1 to 50% by mass with respect to the mass of the laminated electlet non-woven fabric. The components thereof will be described in detail below, but the present invention is not limited to the scope described below as long as the gist thereof is not exceeded.

[Polyolefin-based resin (A), Polyolefin-based resin (B)]
The melt flow rate (MFR) showing the flow characteristics of the polyolefin-based resin (A) of the fiber constituting the spunbonded nonwoven fabric layer and the polyolefin-based resin (B) of the fiber constituting the melt-blown nonwoven fabric layer according to the present invention. (May be abbreviated) adopts the value measured by ASTM D1238 (method A).

According to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C.

First, the MFR of the polyolefin resin (A) of the fiber constituting the spunbonded non-woven fabric layer is preferably 32 to 850 g / 10 minutes. The MFR of the polyolefin resin (A) is 32 g / 10 minutes or more, more preferably 60 g / 10 minutes or more, further preferably 80 g / 10 minutes or more, particularly preferably 120 g / 10 minutes or more, and most preferably 155 g / 10 minutes. That is all. By doing so, when spinning the fibers constituting the spunbonded non-woven fabric layer, the melted polyolefin resin is discharged from the mouthpiece, cooled, and solidified, and the fibers are uniformly thinned (behavior). Hereinafter, it may be abbreviated as fiber thinning behavior), and even if it is drawn at a high spinning speed in order to increase productivity, stable spinning is possible and the thinning behavior is stabilized. As a result, the yarn sway is suppressed, and unevenness when collecting in the form of a sheet is less likely to occur. On the other hand, the MFR of the polyolefin resin (A) is 850 g / 10 minutes or less, more preferably 600 g / 10 minutes or less, and further preferably 400 g / 10 minutes or less. By doing so, it becomes possible to draw the fiber at a stable and high spinning speed, the crystal orientation of the polyolefin resin constituting the fiber is aligned, and the fiber can be made into a fiber having high mechanical strength. preferable.

Further, the MFR of the polyolefin resin (B) of the fibers constituting the melt-blown non-woven fabric layer is preferably 200 to 2500 g / 10 minutes. When the MFR of the polyolefin resin (B) is 200 g / 10 minutes or more, more preferably 400 g / 10 minutes or more, still more preferably 600 g / 10 minutes or more, the thinning behavior when the fibers are stretched is stable. However, even if it is stretched at a high spinning speed in order to increase productivity, it can be spun stably. In addition, by stabilizing the thinning behavior, yarn sway is suppressed, and unevenness when collecting in the form of a sheet is less likely to occur. Further, fibers having an average single fiber diameter of several μm can be easily spun. On the other hand, when the MFR of the polyolefin resin (B) is 2500 g / 10 minutes or less, more preferably 2000 g / 10 minutes or less, and further preferably 1500 g / 10 minutes or less, the tension is increased when the fibers are stretched. It is possible to suppress the increase in thread sway and the decrease in mechanical strength due to the difficulty in applying.

Examples of the polyolefin-based resins (A) and (B) used in the present invention include polyethylene-based resins and polypropylene-based resins. Examples of the polyethylene-based resin include a homopolymer of ethylene or a copolymer of ethylene and various α-olefins. Examples of polypropylene-based resins include homopolymers of propylene and copolymers of propylene and various α-olefins. Among these materials, those mainly composed of polypropylene have particularly excellent electret performance. It is preferable from the viewpoint of exerting it. Further, other components may be copolymerized as long as the properties of the polymer are not impaired.

Regarding the polyolefin resin used in the present invention, the proportion of the homopolymer of propylene is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. Within the above range, good spinnability can be maintained and strength can be improved.

The polyolefin-based resin used in the present invention may be a mixture of two or more kinds, and a resin composition containing other polyolefin-based resin, thermoplastic elastomer, or the like can also be used. Of course, the MFR of the polyolefin-based resin (A) and / or the polyolefin-based resin (B) can be adjusted by blending two or more kinds of resins having different MFRs at an arbitrary ratio. In this case, the MFR of the resin to be blended with the main polyolefin resin is preferably 10 to 1000 g / 10 minutes, more preferably 20 to 800 g / 10 minutes, and further preferably 30 to 600 g / 10 minutes. Is. By doing so, it is possible to prevent the blended polyolefin resin from having partial viscosity unevenness, non-uniform fiber diameter, and deterioration of spinnability.

In the laminated electret non-woven fabric of the present invention, the ratio of the MFR of the polyolefin-based resin (A) to the polyolefin-based resin (B) (MFR _B / MFR _{A) constituting each of the spunbonded non-woven fabric layer and the melt-blown non-woven fabric layer.} ) Is preferably 1 to 13. The ratio of the MFR of the polyolefin resin (A) to the polyolefin resin (B) (MFR _B / MFR _A ) is 1 or more, more preferably 1.5 or more, so that the spunbonded non-woven fabric layer and the melt-blown non-woven fabric layer can be formed. A laminated electret non-woven fabric can be obtained in which the single fiber diameters of the constituent fibers are appropriately balanced, the pressure loss is low, and the collection efficiency is high. On the other hand, the ratio of the MFR of the polyolefin resin (A) to the polyolefin resin (B) (MFR _B / MFR _A ) is 13 or less, more preferably 12 or less, so that the melt blown nonwoven fabric is laminated on the spunbonded nonwoven fabric. Adhesion is easy to proceed, and physical properties such as peeling strength can be improved.

Further, when spinning the fiber described later, this resin is decomposed with respect to the resin used in order to prevent the occurrence of partial viscosity unevenness, make the fineness of the fiber uniform, and further reduce the fiber diameter as described later. It is also conceivable to adjust the MFR. However, for example, it is preferable not to add a peroxide, particularly a free radical agent such as a dialkyl peroxide. When this method is used, viscosity spots are partially generated and the fineness becomes non-uniform, making it difficult to sufficiently reduce the fiber diameter, and spinnability deteriorates due to viscosity spots and air bubbles caused by decomposition gas. In some cases.

The melting point of the polyolefin resin used in the present invention is preferably 80 to 200 ° C, more preferably 100 to 180 ° C. By setting the melting point to preferably 80 ° C. or higher, and more preferably 100 ° C. or higher, it becomes easy to obtain heat resistance that can withstand practical use. Further, by setting the melting point to preferably 200 ° C. or lower, more preferably 180 ° C. or lower, it becomes easier to cool the yarn discharged from the mouthpiece, fusion of fibers is suppressed, and stable spinning becomes easier. The melting point referred to here is a value obtained by measuring with a differential scanning calorimeter (for example, "DSC-2 type" manufactured by PerkinElmer Co., Ltd.) under the condition of a heating rate of 20 ° C./min.

Further, the polyolefin-based resin used in the present invention also contains a commonly used antioxidant, weather stabilizer, light-resistant stabilizer, antistatic agent, antifoaming agent, blocking inhibitor, and lubricant as long as the effects of the present invention are not impaired. , Nuclear agents, additives such as pigments, or other polymers can be added as needed.

The laminated electret non-woven fabric of the present invention can be added with additives such as a heat stabilizer, a weather resistant agent and a polymerization inhibitor, and from the viewpoint of improving the chargeability and charge retention when the non-woven fabric is electret-treated. It is important that the fibrous material contains a hindered amine compound, preferably a compound represented by the general formula (1) (hindered amine compound).

(Here, 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).
It is important that the hindered amine compound is contained in an amount of 0.1 to 5% by mass, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and 0.5% by mass or more as the lower limit. Is particularly preferred. The content is preferably 4% by mass or less, more preferably 3% by mass or less, and particularly preferably 2.5% by mass or less.

Examples of the hindered amine compound include poly [(6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl) ((2,2,6)). 6-Tetramethyl-4-piperidyl) imino) Hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino)] (BASF Japan Co., Ltd., "Kimasorb" (registered trademark) 944LD), Dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (BASF Japan, Inc., "Tinubin"® 622LD), and 2 -(3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalate bis (1,2,2,6,6-pentamethyl-4-piperidyl) (manufactured by BASF Japan Co., Ltd., "Tinubin" (registered trademark) 144),

dibutylamine

1,3,5-triazine N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine N- (2,2,6,6-tetramethyl-4-piperidyl) A polycondensate of butylamine (manufactured by BASF Japan Co., Ltd., "Kimasorb" (registered trademark) 2020FDL) and the like can be mentioned. From the viewpoint of chargeability and charge retention, the compound represented by the above general formula (1) (hindered amine-based additive) is preferable, and specifically, poly [(6- (1,1,3,3-tetramethyl) Butyl) Amino-1,3,5-triazin-2,4-diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) Hexamethylene ((2,2,6,6-tetra) Methyl-4-piperidyl) imino)] (BASF Japan Co., Ltd., "Kimasorb" (registered trademark) 944LD),

dibutylamine

1,3,5-triazine N, N'-bis (2,2,6) A polycondensate of 6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine / N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (BASF Japan Co., Ltd., "Kimasorb" (registered trademark) 2020FDL) Is preferable.

The hindered amine compound such as a compound having a structure represented by the following general formula (1) may be used alone or as a mixture of a plurality of types.

Among them, it is preferable that the hindered amine compound contains a compound represented by the following general formula (1).

(Here, 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).
By doing so, the electric charge applied by the electric charge can be stabilized more effectively.

By allowing the compound to exist in the laminated electret non-woven fabric, the electric charge applied by charging can be stabilized more effectively. Therefore, when the laminated electret non-woven fabric is used for the air filter unit, the collection performance is improved. It is possible to realize an air filter with high collection performance with low pressure loss.

The fibers constituting the laminated electret non-woven fabric of the present invention may contain a crystal nucleating agent in addition to the compound represented by the above general formula (1).

Examples of the crystal nucleating agent include sorbitol-based nucleating agents, nonitol-based nucleating agents, xylitol-based nucleating agents, phosphoric acid-based nucleating agents, triaminobenzene derivative nucleating agents, and carboxylic acid metal salt nucleating agents.

Sorbitol-based nucleating agents include dibenzylidene sorbitol (DBS), monomethyldibenzylidene sorbitol (eg, 1,3: 2,4-bis (p-methylbenzylidene) sorbitol (p-MDBS)), and dimethyldibenzidene sorbitol (eg, p-MDBS). , 1,3: 2,4-bis (3,4-dimethylbenzylidene) sorbitol (3,4-DMDBS)), "Milllad" (registered trademark) 3988 (manufactured by Milliken Japan Co., Ltd.), and Examples thereof include "Gerol" (registered trademark) E-200 (manufactured by Shin Nihon Rika Co., Ltd.).

Nonitol-based nucleating agents include, for example, 1,2,3-trideoxy-4,6: 5,7-bis-[(4-propylphenyl) methylene] -nonitol and the like, "Millad" (registered trademark). NX8000 (manufactured by Milliken Japan Co., Ltd.) and the like can be mentioned.

Xylitol-based nucleating agents include, for example, bis-1,3: 2,4- (5', 6', 7', 8'-tetrahydro-2-naphthaldehydebenzylidene) 1-allylxylitol and the like. Further, the phosphoric acid-based nucleating agent includes, for example, aluminum-bis (4,4', 6,6'-tetra-tert-butyl-2,2'-methylenediphenyl-phosphate) -hydroxydo, and the like. Examples thereof include "ADEKA STAB" (registered trademark) NA-11 (manufactured by ADEKA Corporation) and "ADEKA STAB" (registered trademark) NA-21 (manufactured by ADEKA Corporation).

The triaminobenzene derivative nucleating agent contains, for example, 1,3,5-tris (2,2-dimethylpropanamide) benzene and the like, and is represented by the following general formula (2), "Irgaclear" (registered trademark). ) XT386 "(manufactured by BASF Japan Ltd.), and the like. Further, the carboxylic acid metal salt nucleating agent includes, for example, sodium benzoate, calcium 1,2-cyclohexanedicarboxylate and the like.

(In the general formula (2), R ₁ , R ₂ and R ₃ are independently alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 3 to 20 carbon atoms, and cycloalkyl groups having 5 to 12 carbon atoms. , A cycloalkenyl group having 5 to 9 carbon atoms, or an aryl group having 6 to 10 carbon atoms.).

The content of the crystal nucleating agent in the fibers constituting the laminated electret non-woven fabric is preferably 0.001 to 1% by mass. When the content of the crystal nucleating agent is 0.001% by mass or more, more preferably 0.005% by mass or more, the effect of the dust collecting property can be effectively enhanced. In addition, fusion between fibers can be suppressed and the amount of airflow can be increased. On the other hand, when the content of the crystal nucleating agent is 1% by mass or less, more preferably 0.5% by mass or less, the spinnability is stable and the cost is superior.

The laminated electret non-woven fabric of the present invention is composed of a polymer containing the above-mentioned compound, and the polymer can be used as a resin material such as an antioxidant, a light stabilizer, and a heat stabilizer in addition to the above-mentioned compound. It may contain a stabilizer that is normally contained.

The contents of the compound represented by the above general formula (1) and the crystal nucleating agent in the present invention are determined as follows.

The content referred to here can be determined, for example, as follows. After Soxhlet extraction of the non-woven fabric with a mixed solution of methanol / chloroform, HPLC fractionation was repeated for the extract, and IR measurement, GC measurement, GC / MS measurement, MALDI-MS measurement, ¹ H-NMR measurement, and 1 H-NMR measurement were repeated for each sample. ¹³ Confirm the structure by C-NMR measurement. The mass of the fraction containing the crystal nucleating agent is totaled, the ratio to the whole non-woven fabric is obtained, and this is taken as the content of the crystal nucleating agent. Similarly, for the compound represented by the above general formula (1), the masses of the preparative products contained therein are totaled, and the ratio to the entire non-woven fabric is calculated and used as the content of the compound.

[fiber]
The fiber formed of the polyolefin resin (A) constituting the spunbonded nonwoven fabric layer according to the present invention has an average single fiber diameter of 6.5 to 22 μm. When the average single fiber diameter is 6.5 μm or more, preferably 7.5 μm or more, more preferably 8.4 μm or more, deterioration of spinnability can be prevented, and a stable and high-quality non-woven fabric can be produced. On the other hand, when the average single fiber diameter is 22 μm or less, preferably 13 μm or less, more preferably 11.2 μm or less, and further preferably 10 μm or less, the denseness and uniformity are high, and the processing characteristics that can withstand practical use are excellent. Further, even when the content ratio of the melt blow nonwoven fabric layer is lowered, the collection efficiency can be high, so that the laminated electret nonwoven fabric having excellent flexibility can be obtained.

In the present invention, the average single fiber diameter (μm) of the fiber formed from the polyolefin resin (A) constituting the spunbonded nonwoven fabric layer adopts a value calculated by the following procedure. And.
(1) Randomly collect small pieces of sample from the laminated electret non-woven fabric.
(2) In the cross section of the collected small piece sample, take a photograph capable of measuring the thickness of the fiber in the range of 500 to 2000 times with a scanning electron microscope or the like.
(3) Ten fibers are arbitrarily selected from the photographs taken of each small piece sample, and the thickness thereof is measured to obtain a single fiber diameter. The fiber diameter of a non-circular fiber is a circumscribed circle and an inscribed circle with respect to the fiber cross section, and the average value of each diameter is taken as a single fiber diameter.
(4) The single fiber diameter calculated by rounding off the second decimal place of the measured single fiber diameter is 6.5 μm or more, and is formed from the polyolefin resin (A) constituting the spunbonded non-woven fabric layer. The single fiber diameter of the resulting fiber.
(5) Small pieces are sampled and measured so that the total number of fibers having a single fiber diameter of 6.5 μm or more is 100, and the arithmetic mean value thereof is defined as the average single fiber diameter (μm).

On the other hand, the fibers formed from the polyolefin resin (B) constituting the melt-blown nonwoven fabric according to the present invention preferably have an average single fiber diameter of 0.1 to 6 μm. When the average single fiber diameter is 0.1 μm or more, more preferably 0.4 μm or more, deterioration of spinnability can be prevented, and a stable and high-quality melt-blown non-woven fabric layer can be formed. On the other hand, when the average single fiber diameter is 6 μm or less, more preferably 5 μm or less, the flexibility and uniformity are high, and even when the content ratio of the melt-blown non-woven fabric layer (M) is lowered, the water resistance can withstand practical use. A laminated non-woven fabric having excellent characteristics can be obtained.

In the present invention, the average single fiber diameter (μm) of the fiber formed from the polyolefin resin (B) constituting the melt-blown non-woven fabric layer is a value calculated by the following procedure.
(1) Randomly collect small pieces of sample from the laminated electret non-woven fabric.
(2) In the cross section of the collected small piece sample, take a photograph capable of measuring the thickness of the fiber in the range of 500 to 2000 times with a scanning electron microscope or the like.
(3) Ten fibers are arbitrarily selected from the photographs taken of each small piece sample, and the thickness thereof is measured to obtain a single fiber diameter.
(4) The single fiber diameter calculated by rounding off the second decimal place of the measured single fiber diameter is 6.0 μm or less, and is formed of the polyolefin resin (B) constituting the melt blown non-woven fabric layer. The single fiber diameter of the fiber.
(5) Small pieces are sampled and measured so that the total number of fibers having a single fiber diameter of 6.0 μm or less is 100, and the arithmetic mean value thereof is defined as the average single fiber diameter (μm).

Further, in the present invention, it can also be used as a composite fiber in which the above-mentioned polyolefin resin is combined. Examples of the composite form of the composite fiber include a composite form such as a concentric sheath type, an eccentric core sheath type, and a sea island type. It is not particularly limited to single component fibers, composite component fibers such as core sheath type and sea island type, but in the case of composite component type fibers, depending on the selection of the resin, the charge is increased due to the difference in electrical resistance between the resins. A single component fiber is a preferred embodiment because it can leak.

Further, 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 is circular, hollow circular, oval, flat, or. Deformed types such as X-type and Y-type, polygonal type, multi-leaf type, and the like are preferable forms. The fiber diameter of a non-circular fiber is obtained by taking an circumscribed circle and an inscribed circle with respect to the fiber cross section and calculating the average value of the respective diameters as the fiber diameter.

[Laminated electret non-woven fabric]
It is important that the laminated electret non-woven fabric of the present invention is formed by laminating a spunbonded non-woven fabric layer and a melt-blown non-woven fabric layer. With this configuration, it is possible to impart workability, collection performance, and flexibility that are higher than the level required for a non-woven fabric for an air filter unit.

The MFR of the laminated electret non-woven fabric of the present invention is preferably 40 g / 10 minutes to 850 g / 10 minutes, more preferably 60 g / 10 minutes or more, still more preferably 80 g / 10 minutes or more, and particularly preferably 120 g / min. 10 minutes or more, most preferably 155 g / 10 minutes or more. As a result, the non-woven fabric can be made into a non-woven fabric with high collection efficiency due to the progress of thinning. On the other hand, by setting the weight to 850 g / 10 minutes or less, preferably 600 g / 10 minutes or less, more preferably 400 g / 10 minutes or less, the finening behavior of the fibers during spinning is stable and the productivity is increased. Even if it is drawn at a very high spinning speed, stable spinning is possible. _{Further, the ratio of MFR (MFR B} / MFR _A ) between the spunbonded non-woven fabric layer and the melt-blown non-woven fabric layer becomes small, and when the melt-blown non-woven fabric is laminated on the spunbonded non-woven fabric, adhesion easily proceeds and physical properties such as peeling strength are improved. Can be made to.

For the MFR of the laminated electret non-woven fabric of the present invention, the value measured by ASTM D1238 (method A) is adopted. According to this standard, for example, polypropylene is measured at a load of 2.16 kg and a temperature of 230 ° C., and polyethylene is measured at a load of 2.16 kg and a temperature of 190 ° C. When multiple types of resins are used, such as different polyolefin resins that make up the spunbonded non-woven fabric layer and melt-blown non-woven fabric layers, the highest measured temperature of each polyolefin-based resin. Measured by temperature.

Further, the laminated electret non-woven fabric of the present invention is charged (electretized). As a result, it is possible to have high collection performance while maintaining the characteristic of low pressure loss due to the electrostatic adsorption effect.

Here, the pressure loss and the collection efficiency in the present invention are measured by the following measuring method or a measuring method that can obtain the same result. That is, five measurement samples of 15 cm × 15 cm were collected from an arbitrary part of the laminated electret non-woven fabric, and the pressure loss and the collection efficiency were measured for each sample by the collection performance measuring device outlined in FIG. do.

Further, it is important that the basis weight of the laminated electret nonwoven fabric according to the present invention is 5 to 80 g / m ^{2 or less.} By setting the basis weight to 5 g / m ² or more, preferably 8 g / m ² or more, and more preferably 10 g / m ² or more, the strength and rigidity of the non-woven fabric can be increased. On the other hand, by setting the basis weight to 80 g / m ² or less, preferably 60 g / m ² or less, more preferably 50 g / m ² or less, and further preferably 40 g / m ² or less, the pressure loss is reduced and the flexibility is also increased. It can be in a preferred range.

In the present invention, the texture of the laminated electret non-woven fabric shall be the value measured by the following procedure in accordance with "6.2 Mass per unit area" of JIS L1913: 2010 "General non-woven fabric test method". do.
(1) Collect three 20 cm × 25 cm test pieces per 1 m of sample width.
(2) Weigh each mass (g) in the standard state.
(3) The arithmetic mean value is ^{expressed by the mass per 1 m 2} (g / m ² ), and the first decimal place is rounded off.

It is important that the content of the melt-blown non-woven fabric layer in the laminated electret non-woven fabric of the present invention is 1 to 50% by mass or less with respect to the mass of the laminated electret non-woven fabric. By setting the content of the melt blow nonwoven fabric layer to 1% by mass or more, preferably 2% by mass or more, the collection efficiency can be improved. Further, the content of the melt blow nonwoven fabric layer is set to 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less, further preferably 12% by mass or less, and most preferably 10% by mass or less. The hardness peculiar to the melt blown non-woven fabric can be reduced, and the moldability of the filter can be improved.

Further, by setting the content of the spunbonded non-woven fabric layer in the laminated electret non-woven fabric to more than 50% by mass and less than 99% by mass, it is possible to obtain a laminated electret non-woven fabric having excellent flexibility and workability.

In the present invention, the content ratio of the melt-blown non-woven fabric layer shall be a value measured by the following procedure.
(1) Three test pieces having a width of 100 mm × 100 mm are collected at equal intervals in the width direction of the laminated electret non-woven fabric.
(2) Collect only the non-adhesive part of the laminated electret non-woven fabric.
(3) The masses of the collected test piece and the melt-blown non-woven fabric collected from the test piece are measured.
(4) Calculate the content ratio of the melt-blown non-woven fabric in the laminated electret non-woven fabric.

The thickness of the laminated electret non-woven fabric of the present invention is preferably 0.05 to 1 mm. When the thickness is 0.05 mm or more, more preferably 0.08 mm or more, still more preferably 0.10 mm or more, the shape retention of the filter medium can be enhanced. On the other hand, when the thickness is 1 mm or less, more preferably 0.8 mm or less, still more preferably 0.5 mm or less, when the laminated electret nonwoven fabric according to the present invention is used as a filter medium for an air filter, the filter medium is stored in the unit. The sex can be improved.

In the present invention, the thickness (mm) of the laminated electret non-woven fabric is set to "6.1.1 A method" of "6.1 thickness (ISO method)" of JIS L1913: 2010 "General non-woven fabric test method". In accordance with this, the values measured by the following procedure shall be adopted.
(1) Using a pressurizer having a diameter of 10 mm, the thickness of 10 points per 1 m is measured in units of 0.01 mm at equal intervals in the width direction of the non-woven fabric under a load of 10 kPa.
(2) Round off the third decimal place of the average value of the above 10 points.

The laminated electret non-woven fabric of the present invention preferably has a longitudinal tensile strength per unit basis weight of 0.3 (N / 5 cm) / (g / m ² ) or more. The longitudinal tensile strength per unit number is 0.3 (N / 5 cm) / (g / m ² ) or more, preferably 0.5 (N / 5 cm) / (g / m ² ) or more, more preferably 1. By setting it to (N / 5 cm) / (g / m ² ) or more, particularly preferably 1.5 (N / 5 cm) / (g / m ² ) or more, it does not break during processing and has excellent workability. Can be. The longitudinal tensile strength per unit grain can be adjusted by adjusting the spinning speed of the fibers constituting the spunbonded non-woven fabric layer, the average single fiber diameter, and the thermal bonding conditions (adhesion rate, temperature, and linear pressure) of the spunbonded non-woven fabric. can. The vertical direction referred to here is the longitudinal direction of the non-woven fabric.

Further, the tensile elongation at maximum strength of the above tensile strength is preferably 15% or more, more preferably 20% or more, and further preferably 30% or more, so that the material breaks during molding or the like. Since it can be processed without being processed, it can be made excellent in processability.

The laminated electret non-woven fabric of the present invention preferably has a pressure loss of 0.1 to 0.5 (Pa) / (g / m ² ) per unit grain. The pressure loss per unit is 0.1 (Pa) / (g / m ² ) or more, more preferably 0.15 (Pa) / (g / m ² ) or more, still more preferably 0.2 (Pa) /. When it is (g / m ² ) or more, the number of fibers contained per unit grain is large or the total surface area is large, so that a laminated electlet non-woven fabric having excellent workability without breaking during processing can be obtained. be able to. On the other hand, 0.5 (Pa) / (g / m ² ) or less, more preferably 0.45 (Pa) / (g / m ² ) or less, still more preferably 0.4 (Pa) / (g / m ^{2) or less.} ) By setting the following, it is possible to obtain a laminated electret non-woven fabric in which the number of fibers contained per unit grain or the total surface area is appropriate and the pressure loss is low.

The laminated structure of the laminated electlet non-woven fabric of the present invention is formed by laminating one spunbonded non-woven fabric layer (S) on one side of the melt-blown non-woven fabric layer (M) (SM) or laminating a plurality of layers (for example, SSM). Laminated electret non-woven fabric, spunbonded non-woven fabric layer is laminated one layer at a time on both sides of the melt-blown non-woven fabric layer (SMS) or multiple layers are laminated (for example, SSMS). The number of laminated spunbonded non-woven fabric layers and the number of laminated spunbonded non-woven fabric layers laminated on the other side may be the same or different). Here, when the total number of laminated non-woven fabric layers of the spunbonded non-woven fabric layer laminated on the melt-blown non-woven fabric layer is a plurality of, each spunbonded non-woven fabric layer may be a spunbonded non-woven fabric layer having the same configuration. The condition is that the hindered amine compound is contained in an amount of 0.1 to 5% by mass, the texture of the laminated electret nonwoven fabric is in ^{the range of 5 to 80 g / m 2} , and the content of the melt blow nonwoven fabric layer is 1 to 50% by mass. The configurations may be different from each other as long as they are satisfied. The spunbonded non-woven fabric layers having different configurations include, for example, different types of fibers constituting one spunbonded non-woven fabric layer and the other spunbonded non-woven fabric layer, different melting points, different single components, and different composite components. If the cross-sectional shape is different, the thickness, strength, and pressure loss are different, any combination thereof may be used as long as the object of the present invention can be achieved. Then, it can be appropriately selected and used according to the purpose.

[Manufacturing method of laminated electret non-woven fabric]
Next, an example of the method for producing the laminated electret nonwoven fabric of the present invention will be described.

The laminated electret non-woven fabric of the present invention is composed of a non-woven fabric manufactured by the spunbond (S) method and the melt blow (M) method. The method for producing a laminated electret non-woven fabric of the present invention can be carried out according to any method as long as the spunbonded non-woven fabric layer and the melt-blown non-woven fabric layer can be laminated. For example, a method in which fibers formed by the melt-blow method are directly deposited on a non-woven fabric layer obtained by the spunbond method to form a melt-blow non-woven fabric layer, and then the spunbond non-woven fabric layer and the melt-blow non-woven fabric layer are fused, span. A method of superimposing a bonded non-woven fabric layer and a melt-blown non-woven fabric layer and fusing the two non-woven fabric layers by heating and pressurizing. A method of bonding or the like can be adopted. From the viewpoint of productivity, a method of directly forming the melt-blown non-woven fabric layer on the spunbonded non-woven fabric layer is a preferable embodiment.

Further, depending on the purpose, the spunbonded non-woven fabric layer (S) and the melt-blown non-woven fabric layer (M) can be laminated with SM, SMS, SMMS, SMSMS, SMS, or the like as described above.

In the spunbonded non-woven fabric layer according to the present invention, first, a molten polyolefin resin is spun from a spinneret as long fibers, which is suction-stretched with compressed air by an ejector, and then the fibers are collected on a moving net. Layer the non-woven fabric.

As the shape of the spinneret and the ejector, various shapes such as a round shape and a rectangular shape can be adopted. Among them, the combination of a rectangular base and a rectangular ejector is possible because the amount of compressed air used is relatively small and the energy cost is excellent, the threads are less likely to be fused or scratched, and the threads can be easily opened. It is preferably used.

In the present invention, the polyolefin resin is melted in an extruder, weighed and supplied to a spinneret, and spun as long fibers. The spinning temperature when the polyolefin resin is melted and spun is preferably 200 to 270 ° C. The spinning temperature is 200 ° C. or higher, more preferably 210 ° C. or higher, further preferably 220 ° C. or higher, or 270 ° C. or lower, more preferably 260 ° C. or lower, still more preferably 250 ° C. or lower. , A stable molten state can be obtained, and excellent spinning stability can be obtained.

The spun long fiber yarn is then cooled. Examples of the method of cooling the spun yarn include a method of forcibly blowing cold air on the yarn, a method of naturally cooling at the atmospheric temperature around the yarn, and a method of adjusting the distance between the spinneret and the ejector. Etc., or a method of combining these methods can be adopted. Further, the cooling conditions can be appropriately adjusted and adopted in consideration of the discharge amount per single hole of the spinneret, the spinning temperature, the atmospheric temperature and the like.

Next, the cooled and solidified yarn is towed and stretched by the compressed air injected from the ejector. The spinning speed is preferably 3000 to 6500 m / min. By setting the spinning speed to 3000 to 6500 m / min, more preferably 3500 to 6500 m / min, and even more preferably 4000 to 6500 m / min, high productivity can be obtained, and the polyolefin-based fiber constituting the fiber can be obtained. The crystal orientation of the resin proceeds in the same direction, and high-strength long fibers can be obtained. Normally, as the spinning speed is increased, the spinnability deteriorates and the filamentous shape cannot be stably produced. However, as described above, by using a polyolefin resin having a specific range of MFR, the intended polyolefin fiber is used. Can be stably spun.

Subsequently, the obtained long fibers are collected on a moving net to form a non-woven fabric layer. In the present invention, it is also a preferred embodiment that the heat flat roll is brought into contact with the non-woven fabric layer from one side on the net to temporarily bond the non-woven fabric layer. By doing so, it is possible to prevent the surface layer of the non-woven fabric layer from being turned over or blown off during transportation on the net and to deteriorate the formation, and to improve the transportability from collecting the threads to heat bonding. Can be improved.

In the present invention, it is a preferable aspect for an air filter application that the intersections of the obtained non-woven fiber webs are temporarily bonded with a heat flat roll before heat bonding.

It is preferable that the surface temperature of the thermal flat roll at the time of thermal temporary bonding is -60 to -25 ° C with respect to the melting point of the polyolefin resin used. By setting the surface temperature of the thermal flat roll to −60 ° C. or higher with respect to the melting point of the polyolefin resin, more preferably −55 ° C. or higher with respect to the melting point of the polyolefin resin, excessive thermal bonding is suppressed during the thermal bonding described above. However, it is possible to obtain strength and breathability suitable for use in air filter applications. Further, by setting the surface temperature of the thermal flat roll to −25 ° C. or lower with respect to the melting point of the polyolefin resin, more preferably −30 ° C. or lower with respect to the melting point of the polyolefin resin, the film formation of the non-woven fabric surface is suppressed. However, it is possible to obtain appropriate air permeability. When two or more types of polyolefin resins are blended and two or more melting points are observed, the temperature is adjusted to be within the above range with respect to the lowest temperature among the melting points of each polyolefin resin. do.

Next, as the melt blown non-woven fabric, a conventionally known method can be adopted. First, the polyolefin-based resin is melted in an extruder and supplied to the mouthpiece, and hot air is blown onto the threads extruded from the mouthpiece to make the yarn thinner, and then a non-woven fabric layer is formed on the collection net. In the melt blow method, fine fibers of several μm can be easily obtained without requiring a complicated process, and high collection efficiency can be easily achieved.

Subsequently, the obtained laminated non-woven fabric layer and the melt-blown non-woven fabric layer are laminated, and these are heat-bonded to obtain the intended laminated non-woven fabric.

The above-mentioned method of heat-bonding the heat-temporarily bonded non-woven layer includes a heat-embossed roll in which a pair of upper and lower roll surfaces are engraved (concavo-convex parts), and a roll in which one roll surface is flat (smooth). A method of heat bonding with various rolls, such as a thermal embossing roll consisting of a roll with engraving (unevenness) on the surface of the other roll, and a thermal calendar roll consisting of a pair of upper and lower flat (smooth) rolls. , A method such as ultrasonic bonding in which heat welding is performed by ultrasonic vibration of a horn. Among them, it is highly productive, it can give strength with a partial heat-bonded part, and it can maintain the texture and feel unique to non-woven fabric with a non-bonded part. ) Is applied, or a heat embossed roll consisting of a roll having a flat (smooth) surface on one roll and a roll having an engraving (unevenness) on the surface of the other roll is preferably used. It is an aspect.

As the surface material of the heat embossed roll, a metal roll and a metal roll are used in order to obtain a sufficient heat bonding effect and prevent the engraving (concavo-convex part) of one embossed roll from being transferred to the surface of the other roll. A pair is a preferred embodiment.

The embossing adhesion area ratio by such a heat embossing roll is preferably 3 to 30%. By setting the bonding area to 3% or more, more preferably 5% or more, and further preferably 8% or more, strength that can be put into practical use as a non-woven fabric can be obtained. On the other hand, by setting the adhesive area to preferably 30% or less, more preferably 25% or less, and further preferably 20% or less, it is possible to secure appropriate air permeability particularly suitable for use in air filter applications. can. Even when ultrasonic bonding is used, the bonding area ratio is preferably in the same range.

The adhesive area here refers to the ratio of the adhesive portion to the entire laminated non-woven fabric. Specifically, when heat-bonding is performed by a roll having a pair of irregularities, the convex portion of the upper roll and the convex portion of the lower roll overlap and occupy the entire laminated non-woven fabric of the portion (adhesive portion) that abuts on the non-woven fabric layer. Say the percentage. Further, in the case of thermal bonding between a roll having irregularities and a flat roll, it means the ratio of the convex portion of the roll having irregularities to the entire laminated nonwoven fabric of the portion (adhesive portion) in contact with the non-woven fabric layer. Further, in the case of ultrasonic bonding, it refers to the ratio of the portion (adhesive portion) to be heat-welded by ultrasonic processing to the entire laminated non-woven fabric.

As the shape of the bonded portion by thermal embossing roll or ultrasonic bonding, a circle, an ellipse, a square, a rectangle, a parallelogram, a rhombus, a regular hexagon, a regular octagon, etc. can be used. Further, it is preferable that the bonded portions are uniformly present at regular intervals in the longitudinal direction (conveying direction) and the width direction of the spunbonded nonwoven fabric layer. By doing so, it is possible to reduce variations in the strength of the spunbonded non-woven fabric layer.

It is preferable that the surface temperature of the heat embossed roll at the time of heat bonding is −50 to −15 ° C. with respect to the melting point of the polyolefin resin used. By setting the surface temperature of the thermal roll to −50 ° C. or higher with respect to the melting point of the polyolefin resin, and more preferably −45 ° C. or higher with respect to the melting point of the polyolefin resin, the strength that can be appropriately heat-bonded and put into practical use. Spunbonded non-woven fabric can be obtained. Further, by setting the surface temperature of the heat embossed roll to -15 ° C. or lower with respect to the melting point of the polyolefin resin, and more preferably -20 ° C. or lower with respect to the melting point of the polyolefin resin, excessive thermal adhesion is suppressed. As a laminated non-woven fabric, it is possible to obtain appropriate air permeability and processability particularly suitable for use in air filter applications.

When two or more types of polyolefin resins are blended and two or more melting points are observed, the temperature is adjusted to be within the above range with respect to the lowest temperature among the melting points of each polyolefin resin. And.

The linear pressure of the heat embossing roll at the time of heat bonding is preferably 10 to 500 N / cm. The linear pressure of the roll is preferably 10 N / cm or more, more preferably 50 N / cm or more, further preferably 100 N / cm or more, and particularly preferably 150 N / cm, so that it can be appropriately heat-bonded and put into practical use. A laminated non-woven fabric having a high strength can be obtained. On the other hand, by setting the linear pressure of the heat embossed roll to preferably 500 N / cm or less, more preferably 400 N / cm or less, and further preferably 300 N / cm or less, it is used as a laminated electret non-woven fabric, especially for air filter applications. It is possible to obtain appropriate breathability and workability suitable for.

Further, in the present invention, for the purpose of adjusting the thickness of the laminated electret non-woven fabric, heat bonding is performed by a heat calendar roll composed of a pair of upper and lower flat rolls before and / or after heat bonding by the above heat embossing roll. Can be done. A pair of upper and lower flat rolls is a metal roll or an elastic roll having no unevenness on the surface of the roll, and a metal roll and a metal roll may be paired, or a metal roll and an elastic roll may be paired. Can be used.

Further, the elastic roll here is a roll made of a material having elasticity as compared with a metal roll. Elastic rolls include so-called paper rolls such as paper, cotton and aramid paper, and resin rolls made of urethane-based resin, epoxy-based resin, silicon-based resin, polyester-based resin and hard rubber, and a mixture thereof. And so on.

In manufacturing the laminated electret non-woven fabric, the charging method is not particularly limited, and the corona discharge method, the hydrocharge method, the thermal electret method and the like are preferably used. The method of applying water in the hydrocharging method is a method of immersing water in a non-woven fabric sheet, a method of spraying water on the non-woven fabric sheet, a method of spraying water in a thread shape directly under the mouthpiece, or a combination of these methods as appropriate. May be good. Further, the charging process may be continuously performed at the time of manufacturing the non-woven fabric, or the manufactured non-woven fabric may be wound once and processed in a separate step.

[Reinforcing material]
By adhering the reinforcing material according to the present invention to a part of the mountain portion of the pleated filter medium, it is possible to obtain the effect of suppressing the deformation of the filter medium against the external force in the mountain valley folding direction on the air filter unit.

The composition of the reinforcing material can be arbitrarily selected as long as it has breathability, but it is preferable to use a non-woven fabric that can be easily adjusted to the desired breathability and rigidity by adjusting the type of fiber used and the basis weight. ..

The non-woven fabric that can be used as the reinforcing material can be manufactured by a known method such as a chemical bond method, a wet papermaking method, a spunbond method, a melt blow method, a spunlace method, or an airlaid method. Above all, it is preferable to use a non-woven fabric produced by a spun bond method or a chemical bond method, which can easily impart high rigidity as a reinforcing material.

The basis weight of the reinforcing material ^{is preferably 100 to 400 g / m 2} from the viewpoint of strength and cost, the lower limit is ^{more preferably 130 g / m 2} or more, and the upper limit is 300 g / m ² or less. It is more preferable to do so.

The thickness of the reinforcing material is preferably 0.3 to 1.5 mm from the viewpoint of ensuring strength against tearing and the ease of cutting to a desired size, and the lower limit thereof is 0.5 mm or more. The upper limit thereof is more preferably 1.3 mm or less.

[Pleated joint]
The pleated joint according to the present invention is composed of the above-mentioned filter medium and reinforcing material.

In the pleated joint according to the present invention, the filter medium forms a three-dimensional shape having peaks and valleys in a pleated state. Here, the pleated folding process is a process in which the above-mentioned filtration sheet or a laminate of the same sheet and another sheet is folded in a certain direction in a mountain valley shape at a predetermined folding height, and the folding method is a reciprocating type or a rotary. A method such as an expression can be used. By pleating, a larger area of filter media can be mounted as a filter in a certain volume, the wind speed through the filter media with respect to the passage of air is reduced, the pressure loss is reduced, and the ventilation resistance is reduced, that is, ventilation. An air filter unit having excellent properties can be obtained. Then, one of the surfaces of the filter medium becomes the inflow surface of air when mounted on the air purifier, and the opposite surface becomes the outflow surface.

Further, in order to keep the distance between the plurality of mountain valley shapes formed by the pleating process constant, a separator can be provided in the space generated between the adjacent mountains. Using a known method such as bead bonding in which molten resin is applied linearly along the ridgeline of the pleated peaks and adjacent resins are bonded and fixed to each other, the intervals between the filter media pleated into a plurality of peaks and valleys are fixed. May be retained by.

Further, the thickness of the filter medium is preferably 0.1 to 0.75 mm from the viewpoint of having a certain strength and increasing the area that can be accommodated in a certain volume when pleated. It is more preferable that the lower limit is 0.2 mm or more and the upper limit is 0.65 mm or less.

When a PTFE film or the like is further laminated on the filter medium, the combined thickness has a certain strength, and the filter medium obtained by pleating is 0.4. The lower limit is preferably 0.5 mm or more, and the upper limit is more preferably 1.75 mm or less.

In the pleated joint according to the present invention, the reinforcing material is fixed to the filter medium via two or more ridges out of seven ridges from the end of the pleats of the filter medium in the mountain valley folding direction. ing. As a result, two or more mountain portions are connected by the reinforcing material, and the distance between the connected mountain portions is maintained against an external force. In addition, the reinforcing material may extend from the end portion to eight or more mountain portions, and a part of the mountain portion and the reinforcing material may be adhered to each other to fix the reinforcing material. Further, the reinforcing material may be present on one end side of the air filter in the mountain / valley folding direction, but may also be present on the other end side.

As a method for adhering the mountain portion of the filter medium and the reinforcing material, a moisture / moisture curable adhesive such as a cyanoacrylate monomer or an isocyanate-based compound, a polyolefin-based resin, an ethylene-vinyl acetate copolymer resin, or the like, etc. An adhesive such as a heat-sealing adhesive may be applied to the surface of the reinforcing material and / or near the apex on the ridge of the filter filter material to bond the two, or the reinforcing material may be low due to polypropylene fibers or copolymerization. A method of heating a reinforcing material to weld a low melting point part and adhering it to the apex part of a filter filter medium using a material composed of a heat-sealing material such as melting point polyester. / Or can be selected from known methods such as a method of melt-bonding the contact portion of the mountain portion of the filter medium.

Further, the pleated joint according to the present invention may have a deodorant sandwiched between the filter medium and the reinforcing material. In this case, it is preferable that the reinforcing material has an effect of suppressing the deodorant from falling off.

The deodorant referred to here has the property of removing offensive odorous gas components such as ammonia and aldehydes by adsorption and reaction. Examples of the type include porous substances such as activated carbon, porous silica particles, zeolite, and sepiolite, and composites of these with a drug that enhances the reactivity with a peculiar gas component. Here, as a drug that enhances the reactivity with a peculiar gas component, an amine-based drug such as adipic acid dihydrazide or succinic acid hydrazide, an acid-based drug such as phosphoric acid, or an alkaline drug such as sodium hydroxide or potassium hydroxide is used. Drugs can be mentioned. Among them, activated carbon or porous silica particles have a large pore volume and have pores with a wide diameter and can remove various gases. Therefore, activated carbon, porous silica particles and gas components peculiar to them are used. It is preferable to use at least one selected from the group composed of a complex with an agent that enhances the reactivity of the deodorant.

The deodorant is preferable because the total amount of the deodorant used is in the ^{range of 40 to 500 g / m 2} so that the gas component in the air is efficiently adsorbed and the air permeability of the filter medium is not impaired.

[Reinforced air filter unit]
The reinforced air filter unit according to the present invention is formed by gripping the pleated joint body with a fixing material.

The fixing material according to the present invention is a fixing material that exists in the direction perpendicular to the direction of the ridgeline of the mountain portion in the reinforced air filter unit and is fixed to the end of the filter medium in the direction of the ridgeline of the mountain portion of the filter medium. Point to. The fixing material exists on two opposite sides of the filter medium, but may be in the form of surrounding the filter medium. When the fixing material surrounds the outer circumference of the filter medium, the fixing material may be referred to as a frame. By having the fixing material, the filter unit can be held in a predetermined shape. As the material used for the fixing material, a known material such as a non-woven fabric, paper, urethane foam, or other foamed resin can be used. As a method of adhering the fixing material member to the side surface of the filter filter medium, a heat-sealing adhesive such as a polyolefin resin or an ethylene-vinyl acetate copolymer resin is applied to the surface of the fixing material member, and the side surface of the filter filter medium is applied. There are methods such as crimping, solidifying and adhering to. Further, the fixing material and the reinforcing material can be made of the same member. In this case, as a method of adhering to the side surface of the filter medium and the mountain portion of the pleats, a fold groove is formed in advance in the flat plate-shaped reinforcing material, and a part of the material is attached to the side surface of the filter medium, and then the fold groove is formed. A method of bending a reinforcing material at the boundary and adhering it to the mountain part of the pleats can be mentioned.

The reinforced air filter unit according to the present invention is suitable for air filter applications. A particularly preferred embodiment is an air purifier in which the reinforced air filter unit is incorporated. Since the reinforced air filter unit has a low pressure loss and a high collection performance, this air purifier has an effect that it can be continuously used for a long time while maintaining a high collection performance.

Next, the laminated electret nonwoven fabric of the present invention will be described based on examples. However, the present invention is not limited to these examples, and any design modification according to the gist described in the present specification is included in the technical scope of the present invention. In addition, in the measurement of each physical property, if there is no particular description, the measurement is performed based on the above method.

[Measuring method]
(1) Metsuke of laminated electret non-woven fabric (g / m ² ):
The measurement was performed based on the above method.

(2) Average single fiber diameter (μm) of fiber:
As a scanning electron microscope, a scanning electron microscope "VHX-D500" manufactured by KEYENCE CORPORATION was used, and measurement was performed based on the above method.

(3) Thickness of laminated electret non-woven fabric (mm):
The measurement was performed according to the above method using a thickness gauge (“TECLOCK” (registered trademark) SM-114 manufactured by Teclock Co., Ltd.).

(4) Collection performance of laminated electret non-woven fabric (collection efficiency (%), pressure loss (Pa), QF value (Pa ^-1 )):
Measurement samples of vertical × horizontal = 15 cm × 15 cm were collected at five locations in the width direction of the laminated electret non-woven fabric, and the collection efficiency of each sample was measured using the collection efficiency measuring device shown in FIG. In the collection efficiency measuring device of FIG. 1, a dust storage box 2 is connected to the upstream side of the sample holder 1 in which the measurement sample M is set, and a flow meter 3, a flow rate adjusting valve 4 and a blower 5 are connected to the downstream side. Has been done. Further, using the particle counter 6 provided in the sample holder 1, 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, respectively. Further, the sample holder 1 is provided with a pressure gauge 8, and can read the static pressure difference between the upstream and the downstream of the measurement sample M.

In measuring the collection efficiency, a polystyrene 0.309U 10% solution (manufacturer: Nacalai Tesque Co., Ltd.) is diluted up to 200 times with distilled water and filled in the dust storage box 2. Next, the measurement sample M is set in the sample holder 1, 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 10,000 particles / (2.83). × ¹⁰ -4 ^{m 3)} or more 40,000 /(2.83×10 ^-4 m ³⁾ the range of (2.83 × ¹⁰ -4 ^{m 3} stabilizes in a range of equal to 0.01ft ^3), The number of dust D upstream and the number d downstream of the measurement sample M were measured three times per measurement sample with a particle counter 6 (“KC-01D” manufactured by Rion Co., Ltd.), and JIS K0901: 1991 “in gas”. In accordance with "5.2 Collection Rate Test" and "5.3 Pressure Loss Test" of "Shape, Dimensions and Performance Test Method of Dust Sample Collection Filter Material", use the following formula to calculate 0. The collection efficiency (%) of particles of 3 to 0.5 μm was determined. The average value of the three measurement samples was used as the final collection efficiency. Collection efficiency (%) = [1- (d / D)] × 100
(However, d represents the total number of downstream dusts measured three times, and D represents the total number of upstream dusts measured three times.).

The higher the collection of the non-woven fabric, the smaller the number of downstream dusts, and therefore the higher the collection efficiency value. Further, the pressure loss was obtained by reading the static pressure difference between the upstream and the downstream of the measurement sample M at the time of measuring the collection efficiency with the pressure gauge 8. The average value of the five measurement samples was taken as the final pressure drop. When the pressure loss is 25 Pa or less and the QF value, which is an index of collection performance calculated according to the following formula, is 0.15 Pa ^-1 or more, the QF value (Pa ^-1 ) = -Ln (1-collection efficiency (%) / 100) / pressure loss (Pa).

(5) Tensile strength per unit basis weight of laminated electret non-woven fabric ((N / 5 cm) / (g / m ² )):
The tensile strength in the vertical direction is as follows, in accordance with JIS L1913: 2010 "General non-woven fabric test method""6.3 Tensile strength and elongation (ISO method)""6.3.1 Standard time". The value measured in shall be adopted.
(A) Two test pieces having a width of 5 cm × 30 cm are collected from the laminated electret non-woven fabric.
(B) Grasp the test piece and set it in the tensile tester at an interval of 20 cm.
(C) A tensile test is performed at a tensile speed of 10 cm / min, and the strength when the sample breaks is defined as the tensile strength (N / 5 cm), and the average value of the three points is calculated by rounding off the second decimal place. The tensile strength of the non-woven fabric per unit basis weight is calculated by dividing the tensile strength obtained here by the basis weight measured in (1) above. In addition, when it was 0.3 (N / 5cm) / (g / m ² ) or more, it was considered that there was tensile strength.

(6) Pressure loss per unit basis weight of laminated electret non-woven fabric ((Pa) / (g / m ² )):
By dividing the pressure loss measured in (4) above by the scale measured in (1) above, the pressure loss of the non-woven fabric per unit scale is calculated, and the obtained value is rounded off to the third decimal place. When the pressure loss of the non-woven fabric per unit basis weight was 0.5 (Pa) / (g / m ² ) or less, it was judged to be acceptable.

(7) Density of laminated electret non-woven fabric (g / cm ³ ):
The density of the non-woven fabric is calculated by dividing the basis weight measured in (1) above by the thickness measured in (3) above. The obtained value was rounded to the fourth decimal place to calculate ^{the density (g / cm 3) of the laminated electret non-woven fabric.}

(8) Flexibility (processability) of laminated electret non-woven fabric:
As a sensory evaluation of the tactile sensation of the laminated electret non-woven fabric, the flexibility was scored according to the following criteria. This was performed by 10 people, and the average was evaluated as the texture of the non-woven fabric. It was judged that the higher each score was, the more flexible it was and the better the workability in various processing, and 4.0 points or more were passed.
<Flexibility (workability)>
5 points: Flexible (good workability)
4 points: Intermediate between 5 points and 3 points 3 points: Normal 2 points: Intermediate between 3 points and 1 point 1 point: Hard (poor workability).

(9) Pleat moldability (easiness to mold):
The laminated electret non-woven fabric was pleated, and the moldability was confirmed and evaluated in three stages of A, B, and C.
A: The pleated formability is good, and the pleated peak shape is an acute angle.
B: Pleated molding can be performed, but the pleated peaks are round. (Evaluation between A and C)
C: Does not retain the pleated shape.

[Example 1]
(Spanbond non-woven fabric layer (lower layer))
A polyolefin resin containing 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Co., Ltd.) represented by compound A in a polypropylene resin formed of a homopolymer having an MFR of 200 g / 10 minutes. A thread spun from a rectangular mouthpiece having a hole diameter of 0.30 mm and a hole depth of 2 mm at a spinning temperature of 235 ° C. and a single-hole discharge rate of 0.32 g / min was cooled and solidified by melting with an extruder. After that, it was towed and stretched by compressed air having an ejector pressure of 0.35 MPa with a rectangular ejector, and collected on a collection net. The obtained non-woven fiber web was heat-temporarily bonded at a temperature of 120 ° C. using a flat roll. A spunbonded non-woven fabric layer having ^{a basis weight of 7.0 g / m 2} of the obtained heat-temporarily bonded non-woven web was formed. The average single fiber diameter was 10.1 μm, and the spinnability was good with no yarn breakage after spinning for 1 hour.

(Melt blow non-woven fabric layer)
Next, a polyolefin resin containing 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) represented by compound A in a polypropylene resin having an MFR of 1100 g / min formed of a homopolymer. The resin was melted by an extruder and spun from a base having a pore diameter of 0.25 mm at a spinning temperature of 260 ° C. and a single-hole discharge rate of 0.10 g / min. Then, air was injected into the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and collected on the spunbonded non-woven fabric layer to form a melt-blown non-woven fabric layer. At this time, the basis weight of the melt-blown non-woven fabric layer separately collected on the collection net under the same conditions was 1.0 g / m ² , and the average single fiber diameter was 1.5 μm.

(Spanbond non-woven fabric layer (upper layer))
Further, polypropylene filaments were collected on the melt-blown non-woven fabric layer under the same conditions as the condition for forming the lower spunbonded non-woven fabric layer to form the spunbonded non-woven fabric layer. As a result, a spunbond-melt blow-spunbond (SMS) laminated fiber web having a total basis weight of 15.0 g / m ^{2 was obtained.}

(Laminated non-woven fabric)
Subsequently, the obtained laminated fiber web was used as an embossing roll having an adhesive area ratio of 16% with a metal polka dot pattern engraved on the upper roll, and a pair of upper and lower thermal embossing composed of a metal flat roll on the lower roll. Using a roll, a laminated non-woven fabric having a linear pressure of 30 N / cm and a heat bonding temperature of 130 ° C. was heat-bonded to obtain a laminated non-woven fabric having a ^{grain size of 15.0 g / m 2.}

(Laminated electret non-woven fabric)
Water permeates the entire surface of the fiber sheet by sucking water by bringing a slit-shaped suction nozzle into contact with the surface of the laminated non-woven fabric while running along the water surface of the water tank to which pure water is supplied. Then, after draining, the non-woven fabric was dried with hot air at a temperature of 100 ° C. to obtain a laminated electret non-woven fabric. Tables 1 and 2 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

(Filter material)
The obtained laminated electret non-woven fabric was slit to a width of 238 mm and then continuously pleated for 80 ridges at a folding height of 30 mm in the direction perpendicular to the slit width to obtain a pleated filter medium.

(Air filter unit)
The polyester fiber and the acrylic resin are composed of a mass ratio of 5: 5 in the direction perpendicular to the direction of the ridgeline of the pleated mountain so that the pitch of the adjacent pleated mountain of the pleated filter medium is about 5.0 mm. A chemical bond non-woven fabric with a grain size of 250 g / m ² , a thickness of 1.1 mm, and a width of 32 mm is used as a fixing material, and a polyolefin-based heat-sealing adhesive is applied and attached to the surface, and molded into an air filter unit with a length of 400 mm and a width of 238 mm. did.

(Reinforced air filter)
A spunbonded non-woven fabric (“Axter” (registered trademark) “G2260-1SBKO” manufactured by Toray Industries, Inc.) with a ^{breathability of 12 cm 3} / (cm ² seconds) was cut out from the obtained air filter unit as a reinforcing material. Four sheets having a length of 7 mm and a width of 130 mm were prepared. Reinforcing material is adhered to the pleated ridges at a total of four locations on both the upstream and downstream sides of the air of the air filter unit, and at both ends in the mountain valley folding direction, to obtain a reinforced air filter. rice field. Table 2 shows the pleated formability of the filter unit.

[Example 2]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Whereas a polypropylene resin made of a homopolymer having an MFR of 200 g / 10 minutes was used, a polypropylene resin made of a homopolymer having an MFR of 800 g / 10 minutes was used. A spunbonded non-woven fabric layer made of polypropylene filaments was formed in the same manner as in Example 1 except that the amount of 0.32 g / min was changed to 0.21 g / min. The characteristics of the long fibers constituting the formed spunbonded non-woven fabric layer were that each spunbonded non-woven fabric layer had a texture of 7.0 g / m ² and an average single fiber diameter of 7.2 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
A melt-blown non-woven fabric layer was formed in the same manner as in Example 1 except that the air pressure was changed from 0.10 MPa to 0.20 MPa. The characteristics of the fibers constituting the formed melt-blow non-woven fabric layer were 1.0 g / m ^{2 for} the basis weight of the melt-blow non-woven fabric layer and 1.0 μm for the average single fiber diameter.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 15.0 g / m 2 was obtained.} Tables 1 and 2 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

(Air filter unit-reinforced air filter)
With respect to the obtained laminated electret non-woven fabric, an air filter unit and a reinforced air filter were obtained in the same manner as in Example 1. Table 2 shows the pleated formability of the filter unit.

[Example 3]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Whereas a polypropylene resin made of a homopolymer having an MFR of 200 g / 10 minutes was used, a polypropylene resin made of a homopolymer having an MFR of 39 g / 10 minutes was used. A spunbonded non-woven fabric layer made of polypropylene filaments was formed in the same manner as in Example 1 except that the amount of 0.32 g / min was changed to 0.65 g / min. The characteristics of the long fibers constituting the formed spunbonded non-woven fabric layer were that each spunbonded non-woven fabric layer had a texture of 7.0 g / m ² and an average single fiber diameter of 21.5 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
Example 1 and Example 1 except that a polypropylene resin having an MFR of 1100 g / 10 min was used instead of a polypropylene resin having an MFR of 500 g / 10 min. A melt blown non-woven fabric layer was formed in the same manner. The characteristics of the fibers constituting the formed melt-blow non-woven fabric layer were that the basis weight of the melt-blow non-woven fabric layer was 1.0 g / m ² , and the average single fiber diameter was 4.1 μm.

[Example 4]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Hindered amine compound A "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Co., Ltd.) 1% by mass in a polypropylene resin formed of a homopolymer having an MFR of 200 g / 10 minutes, and a crystal nucleating agent represented by compound B. A polyolefin resin containing 0.05% by mass of "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Co., Ltd.) is melted by an extruder to form a rectangular base with a hole diameter of 0.30 mm and a hole depth of 2 mm. The yarn spun at a spinning temperature of 235 ° C. and a single-hole discharge rate of 0.32 g / min was cooled and solidified, and then pulled and stretched by compressed air having an ejector pressure of 0.35 MPa with a rectangular ejector. Collected on the collection net. The obtained non-woven fiber web was heat-temporarily bonded at a temperature of 120 ° C. using a flat roll. The characteristics of the long fibers constituting the formed spunbonded non-woven fabric layer were that each spunbonded non-woven fabric layer had a texture of 7.0 g / m ² and an average single fiber diameter of 10.0 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
1% by mass of hindered amine compound A "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) and a crystal nucleating agent represented by compound B in a polypropylene resin formed of a homopolymer having an MFR of 1100 g / 10 minutes. A polyolefin resin containing 0.05% by mass of "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) is melted by an extruder, and the spinning temperature is 260 ° C. from a base having a pore diameter of 0.25 mm. , Single-hole discharge rate was 0.10 g / min. Then, air was injected into the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and collected on the spunbonded non-woven fabric layer to form a melt-blown non-woven fabric layer. At this time, the basis weight of the melt-blown non-woven fabric layer separately collected on the collection net under the same conditions was 1.0 g / m ² , and the average single fiber diameter was 1.6 μm.

[Example 5]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Example 4 and Example 4 except that the amount of the crystalline nucleating agent "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) represented by compound B was changed from 0.05% by mass to 0.005% by mass. A spunbonded non-woven fabric layer was obtained in the same manner. The characteristics of the long fibers constituting the formed spunbonded non-woven fabric layer were that each spunbonded non-woven fabric layer ^{had a texture of 7.0 g / m 2} and an average single fiber diameter of 10.1 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
Example 4 and Example 4 except that the amount of the crystal nucleating agent "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) represented by compound B was changed from 0.05% by mass to 0.005% by mass. A melt blown non-woven fabric layer was obtained in the same manner. The characteristics of the fibers constituting the formed melt-blow non-woven fabric layer were 1.0 g / m ^{2 for} the basis weight of the melt-blow non-woven fabric and 1.5 μm for the average single fiber diameter.

[Example 6]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Example 4 and Example 4 except that the amount of the crystalline nucleating agent "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) represented by compound B was changed from 0.05% by mass to 0.5% by mass. A spunbonded non-woven fabric layer was obtained in the same manner. The basis weight of each spunbonded non-woven fabric layer formed was 7.0 g / m ² , and the average single fiber diameter was 10.1 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
Example 4 and Example 4 except that the amount of the crystal nucleating agent "Irgaclear" (registered trademark) XT386 (manufactured by BASF Japan Ltd.) represented by compound B was changed from 0.05% by mass to 0.5% by mass. A melt blown non-woven fabric layer was obtained in the same manner. The characteristics of the fibers constituting the formed melt-blow non-woven fabric layer were 1.0 g / m ^{2 for} the basis weight of the melt-blow non-woven fabric and 1.5 μm for the average single fiber diameter.

[Example 7]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
A polyolefin resin containing 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 2020FDL (manufactured by BASF Japan Co., Ltd.) represented by compound C in a polypropylene resin formed of a homopolymer having an MFR of 200 g / 10 minutes. A thread spun from a rectangular mouthpiece having a hole diameter of 0.30 mm and a hole depth of 2 mm at a spinning temperature of 235 ° C. and a single-hole discharge rate of 0.32 g / min was cooled and solidified by melting with an extruder. After that, it was towed and stretched by compressed air having an ejector pressure of 0.35 MPa with a rectangular ejector, and collected on a collection net. The obtained non-woven fiber web was heat-temporarily bonded using a flat roll at a temperature of 145 ° C., and the obtained heat-temporarily bonded non-woven web was engraved with a metal polka dot pattern on the upper roll. Using an embossing roll with an adhesive area ratio of 16% and a pair of upper and lower thermal embossing rolls composed of metal flat rolls as the lower roll, heat is applied at a linear pressure of 30 N / cm and a thermal bonding temperature of 145 ° C. Glued. The basis weight of each spunbonded non-woven fabric layer formed was 7.0 g / m ² , and the average single fiber diameter was 10.1 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
A polyolefin resin containing 1% by mass of hindered amine compound A "Kimasorb" (registered trademark) 2020FDL (manufactured by BASF Japan Ltd.) in a polypropylene resin formed of a homopolymer having an MFR of 1100 g / 10 min is melted by an extruder. Then, from a base having a hole diameter of 0.25 mm, spinning was performed at a spinning temperature of 260 ° C. and a single-hole discharge rate of 0.10 g / min. Then, air was injected into the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and collected on the spunbonded non-woven fabric layer to form a melt-blown non-woven fabric layer. At this time, the basis weight of the melt-blown non-woven fabric layer separately collected on the collection net under the same conditions was 1.0 g / m ² , and the average single fiber diameter was 1.5 μm.

[Example 8]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
A spunbonded non-woven fabric layer was obtained by the same method as in Example 1 except that the basis weight of each spunbonded nonwoven fabric layer ^{was changed from 7.0 g / m 2} to 28.0 g / m ^2.

(Melt blow non-woven fabric layer)
A melt-blow non-woven fabric layer was obtained in the same manner as in Example 1 except that the basis weight of the melt-blow non-woven fabric layer ^{was changed from 1.0 g / m 2} to 4.0 g / m ^2.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated non-woven fabric having ^{a total basis weight of 60.0 g / m 2 was obtained.} Tables 3 and 4 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

(Air filter unit-reinforced air filter)
With respect to the obtained laminated electret non-woven fabric, an air filter unit and a reinforced air filter were obtained in the same manner as in Example 1. Table 4 shows the pleated formability of the filter unit.

[Example 9]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
A spunbonded non-woven fabric layer was obtained by the same method as in Example 1 except that the basis weight of each spunbonded nonwoven fabric layer ^{was changed from 7.0 g / m 2} to 4.2 g / m ^2.

(Melt blow non-woven fabric layer)
A melt-blow non-woven fabric layer was obtained in the same manner as in Example 1 except that the basis weight of the melt-blow non-woven fabric layer ^{was changed from 1.0 g / m 2} to 0.6 g / m ^2.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 9.0 g / m 2 was obtained.} Tables 3 and 4 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

[Example 10]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Except that the basis weight of the spunbond nonwoven fabric layer was changed from 7.0 g / ^{m 2} to 29.5 g / ^{m 2,} to obtain a spunbonded nonwoven fabric layer in the same manner as in Example 1.

(Melt blow non-woven fabric layer)
A melt-blown non-woven fabric layer was obtained in the same manner as in Example 1.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 60.0 g / m 2 was obtained.} Tables 3 and 4 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

[Example 11]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Except that the basis weight of the spunbond nonwoven fabric layer was changed from 7.0 g / ^{m 2} to 25.5 g / ^{m 2,} to obtain a spunbonded nonwoven fabric layer in the same manner as in Example 1.

(Melt blow non-woven fabric layer)
A melt-blow non-woven fabric layer was obtained in the same manner as in Example 1 except that the basis weight of the melt-blow non-woven fabric layer ^{was changed from 1.0 g / m 2} to 9.0 g / m ^2.

[Example 12]
(Spanbond non-woven fabric layer (lower layer))
Except that the basis weight of the spunbond nonwoven fabric layer was changed from 7.0 g / ^{m 2} to 14.0 g / ^{m 2} was obtained spunbond nonwoven layer in the same manner as in Example 1. The average single fiber diameter was 10.1 μm, and the spinnability was good with no yarn breakage after spinning for 1 hour.

(Melt blow non-woven fabric layer)
Next, a polyolefin resin containing 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) represented by compound A in a polypropylene resin having an MFR of 1100 g / min formed of a homopolymer. The resin was melted by an extruder and spun from a base having a pore diameter of 0.25 mm at a spinning temperature of 260 ° C. and a single-hole discharge rate of 0.10 g / min. Then, air was injected into the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and collected on the spunbonded non-woven fabric layer to form a melt-blown non-woven fabric layer. At this time, the basis weight of the melt-blown non-woven fabric layer separately collected on the collection net under the same conditions was 1.0 g / m ² , and the average single fiber diameter was 1.5 μm. This gave a spunbond-melt blow (SM) laminated fiber web.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 15.0 g / m 2 was obtained.} Tables 3 and 4 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

[Example 13]
(Spanbond non-woven fabric layer (lower layer))
A spunbonded non-woven fabric layer (lower layer) was obtained in the same manner as in Example 1. The basis weight of the obtained spunbonded non-woven fabric layer was 7.0 g / m ² , and the average single fiber diameter was 10.1 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

(Melt blow non-woven fabric layer)
A melt-blown non-woven fabric layer was obtained in the same manner as in Example 1. The obtained melt-blown non-woven fabric layer had a basis weight of 1.0 g / m ² and an average single fiber diameter of 1.5 μm.

(Spanbond non-woven fabric layer (upper layer))
On this melt-blown non-woven fabric layer, a hindered amine compound "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Co., Ltd.) represented by compound A is added to a polypropylene resin formed of a homopolymer having an MFR of 100 g / 10 minutes. A polyolefin resin containing 1% by mass is melted by an extruder and spun from a rectangular mouthpiece having a pore diameter of 0.30 mm and a pore depth of 2 mm at a spinning temperature of 235 ° C and a single pore discharge rate of 0.65 g / min. The thread was cooled and solidified, and then pulled and stretched by compressed air having an ejector pressure of 0.50 MPa with a rectangular ejector, and collected on a collection net. The obtained non-woven fiber web was heat-temporarily bonded at a temperature of 120 ° C. using a flat roll. A spunbonded non-woven fabric layer having ^{a basis weight of 7.0 g / m 2} of the obtained heat-temporarily bonded non-woven web was formed. The average single fiber diameter was 15.3 μm, and the spinnability was good with no yarn breakage after spinning for 1 hour. This gave a spunbond-melt blow-spunbond (SMS) laminated fiber web.

[Comparative Example 1]
A polypropylene resin made of a homopolymer having an MFR of 800 g / min is melted by an extruder and spun from a mouthpiece having a pore diameter of φ0.25 mm at a spinning temperature of 260 ° C. and a single-hole discharge rate of 0.10 g / min. I put it out. Then, air was injected into the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, and collected on the heat-sealing non-woven fabric layer to form a melt-blown non-woven fabric. The basis weight of the non-woven fabric was 15 g / m ² , and the average single fiber diameter was 4.0 μm.

This non-woven fabric was subjected to an electret-forming treatment to obtain an electret melt-blown non-woven fabric. Tables 5 and 6 show the measured values and calculated values of the electret melt blown non-woven fabric.

The obtained non-woven fabric was very excellent in collection efficiency, but inferior in tensile strength and high pressure loss, and did not reach the range where it could be used for air filter applications.

For the obtained electret melt blown non-woven fabric, an air filter unit was obtained in the same manner as in Example 1. Table 6 shows the pleated formability of the filter unit.

[Comparative Example 2]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Same as Example 1 except that the amount of the hindered amine compound A "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) added to each spunbonded non-woven fabric layer was changed from 1% by mass to 0.09% by mass. A spunbonded non-woven fabric layer was obtained by the method.

(Melt blow non-woven fabric layer)
The same method as in Example 1 except that the amount of the hindered amine compound A "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) added to the melt blow nonwoven fabric layer was changed from 1% by mass to 0.09% by mass. A melt blown non-woven fabric layer was obtained.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 15.0 g / m 2 was obtained.} Tables 5 and 6 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

The obtained non-woven fabric had low collection efficiency and did not reach the range where it could be used for air filters.

(Air filter unit)
With respect to the obtained laminated electret non-woven fabric, an air filter unit was obtained in the same manner as in Example 1. Table 6 shows the pleated formability of the filter unit.

[Comparative Example 3]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Whereas a polypropylene resin made of a homopolymer having an MFR of 200 g / 10 minutes was used, a polypropylene resin made of a homopolymer having an MFR of 30 g / 10 minutes was used. A spunbonded non-woven fabric layer made of polypropylene filaments was formed in the same manner as in Example 1 except that the amount of 0.32 g / min was changed to 0.70 g / min. The characteristics of the long fibers constituting the formed spunbonded non-woven fabric layer were that each spunbonded non-woven fabric layer had a texture of 7.0 g / m ² and an average single fiber diameter of 22.5 μm. As for spinnability, no yarn breakage was observed after spinning for 1 hour, which was good.

[Comparative Example 4]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
A spunbonded non-woven fabric layer was obtained in the same manner as in Example 1.

(Melt blow non-woven fabric layer)
A polyolefin resin containing 1% by mass of the hindered amine compound "Kimasorb" (registered trademark) 944LD (manufactured by BASF Japan Ltd.) represented by compound A in a polypropylene resin formed of a homopolymer having an MFR of 1100 g / min. It was melted by an extruder and spun from a mouthpiece having a pore diameter of 0.25 mm at a spinning temperature of 260 ° C. and a single-hole discharge rate of 0.10 g / min. Then, by injecting air onto the yarn under the conditions of an air temperature of 290 ° C. and an air pressure of 0.10 MPa, a melt-blown non-woven fabric having a grain size of ^{15.0 g / m 2 and an average single fiber diameter of 1.5 μm was produced.} Was laminated on the spunbonded non-woven fabric layer (lower layer) as a melt-blown non-woven fabric layer.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 29.0 g / m 2 was obtained.} Tables 5 and 6 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

The obtained laminated electret non-woven fabric corresponds to a melt-blown non-woven fabric layer having a texture changed ^{from 1.0 g / m 2} to 15.0 g / m ^{2 as compared with the laminated electret non-woven fabric of Example 1.} Since the content of the melt-blown non-woven fabric layer was as high as 51.7%, the pressure loss was high and the flexibility was also low.

(Air filter unit)
With respect to the obtained laminated electret non-woven fabric, an air filter unit was obtained in the same manner as in Example 1. Table 6 shows the pleated formability of the filter unit. As described above, since the flexibility was low, the mountain shape of the pleats became round, the pressure loss due to the structural cause increased, and the workability was not satisfactory.

[Comparative Example 5]
(Spanbond non-woven fabric layer (lower layer) / (upper layer))
Except that the basis weight of the spunbond nonwoven fabric layer was changed from 15.0 g / ^{m 2} to 38.5 g / ^{m 2,} to obtain a spunbonded nonwoven fabric layer in the same manner as in Example 1.

(Melt blow non-woven fabric layer)
A melt-blow non-woven fabric layer was obtained in the same manner as in Example 1 except that the basis weight of the melt-blow non-woven fabric layer ^{was changed from 1.0 g / m 2} to 5.5 g / m ^2.

(Laminated non-woven fabric-laminated electret non-woven fabric)
In the same manner as in Example 1, a laminated electret non-woven fabric having ^{a total basis weight of 82.5 g / m 2 was obtained.} Tables 5 and 6 show the measured values and the calculated values of the obtained laminated electret non-woven fabric.

The obtained non-woven fabric had high pressure loss and low flexibility.

INDUSTRIAL APPLICABILITY According to the present invention, a high-performance laminated electret non-woven fabric having low pressure loss and exhibiting high collection performance can be obtained, and this laminated electret non-woven fabric can be preferably used as a filter medium in an air filter unit, but its application range is limited to these. It's not a thing.

1: Sample holder 2: Dust storage box 3: Flow meter 4: Flow rate adjustment valve 5: Blower 6: Particle counter 7: Switching cock 8: Pressure gauge M: Measurement sample

Claims

Laminated electlet in which a spunbonded non-woven fabric layer made of fibers made of a polyolefin resin (A) and a melt-blown non-woven fabric layer made of fibers made of a polyolefin resin (B) are laminated. The laminated non-woven fabric contains 0.1 to 5% by mass of a hindered amine compound, the laminated electlet non-woven fabric has a texture of 5 to 80 g / m 2 , and further contains the melt-blown non-woven fabric layer. A laminated electrette nonwoven fabric whose amount is 1 to 50% by mass with respect to the mass of the laminated electrette nonwoven fabric.
A laminated electret non-woven fabric having a texture of 5 to 60 g / m 2 and a content of the melt-blown non-woven fabric layer of 1 to 15% by mass with respect to the mass of the laminated electret non-woven fabric.
The laminated electret non-woven fabric according to claim 1 or 2, wherein the laminated electret non-woven fabric contains a crystal nucleating agent.
The laminated electret nonwoven fabric according to claim 3, wherein the crystal nucleating agent is contained in an amount of 0.001 to 1% by mass with respect to the laminated electret nonwoven fabric.
The laminated electret non-woven fabric according to any one of claims 1 to 4, wherein the average single fiber diameter of the fibers constituting the spunbonded non-woven fabric layer is 6.5 to 22 μm.
The laminated electret nonwoven fabric according to any one of claims 1 to 5, wherein the hindered amine compound is a compound represented by the following general formula (1).

(Here, 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).
The laminated electret non-woven fabric according to any one of claims 1 to 6, wherein the melt flow rate (MFR) of the fiber formed from the polyolefin resin (A) is 32 to 850 g / 10 minutes.
The laminated electret nonwoven fabric according to any one of claims 1 to 7, wherein the ratio of the MFR of the polyolefin resin (A) to the polyolefin resin (B) (MFR B / MFR A) is 1 to 13.
The laminated electret non-woven fabric according to any one of claims 1 to 8, wherein the thickness of the laminated electret non-woven fabric is 0.05 to 1 mm.
The laminated electret non-woven fabric according to any one of claims 1 to 9, wherein the tensile strength in the vertical direction per unit basis weight is 0.3 (N / 5 cm) / (g / m 2) or more.
The laminated electret non-woven fabric according to any one of claims 1 to 10, wherein the pressure loss per unit is 0.1 to 0.5 (Pa) / (g / m 2).
An air filter unit in which the laminated electret non-woven fabric according to any one of claims 1 to 11 is used as a filter medium, and a pleated joint formed of the filter medium and the reinforcing material is gripped by a fixing material.
An air purifier incorporating the air filter according to claim 12.