Melt-blown nonwoven fabric and mask filter material

Abstract

To provide a melt-blown nonwoven fabric and a mask having low pressure loss and high collection performance.SOLUTION: There is provided a melt-blown nonwoven fabric primarily composed of non-conductive fibers, wherein the melt-blown nonwoven fabric contains hindered amine compounds of 0.1 mass % or more and 5.0 mass % or less; the non-conductive fibers have an average fiber diameter of 1.0 μm or more and 3.0 μm or less; the melt-blown nonwoven fabrics have a weight of fabric of 8 g / m2 or more and 18 g / m2 or less, and a formation index of 300 or more and 550 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a meltblown nonwoven fabric and a mask filter material. [Background technology]

[0002] BACKGROUND ART Masks using nonwoven fabric as a filter have been used in the past to remove pollen, dust, droplets, and the like from the air.

[0003] In general, it is difficult to reduce pressure loss while increasing collection efficiency in filters using nonwoven fabrics. Therefore, attempts have been made to obtain nonwoven fabrics that are suitable for use as components of filters by subjecting the nonwoven fabrics to electret processing, thereby utilizing electrostatic action in addition to physical action.

[0004] For example, Patent Document 1 proposes a mask that combines low pressure loss with high collection efficiency, consisting of an inner material made of electret melt-blown nonwoven fabric and an outer material made of rayon short fiber nonwoven fabric sandwiched between the inner material.

[0005] Patent Document 2 proposes an air filter material in which polyester spunbond nonwoven fabric is laminated on both sides of an electret meltblown nonwoven fabric made of two types of fibers with different melting points, thereby increasing the adhesion of the meltblown nonwoven fabric and achieving both low pressure loss and high collection efficiency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 61-272063 [Patent Document 2] Re-tabled publication No. 2011 / 004696 Summary of the Invention [Problem to be solved by the invention]

[0007] As proposed in Patent Documents 1 and 2 above, by converting a melt-blown nonwoven fabric into an electret, the collection performance can be improved to some extent. However, when used as a mask filter, for example, there is a demand for a filter with low pressure loss that is easier to breathe without impairing the collection efficiency.

[0008] Therefore, an object of the present invention is to address the above-mentioned problems and to provide a melt-blown nonwoven fabric having low pressure loss and high collection performance. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention has the following configuration. [1] A melt-blown nonwoven fabric mainly comprising non-conductive fibers, wherein the melt-blown nonwoven fabric contains 0.1% by mass or more and 5.0% by mass or less of a hindered amine compound, the average fiber diameter of the non-conductive fibers is 1.0 μm or more and 3.0 μm or less, and the basis weight is 8 g / m 2 More than 18g / m 2 and a texture index of 300 or more and 550 or less. [2] The melt-blown nonwoven fabric according to [1], wherein the non-conductive fibers are made of a polyolefin resin. [3] A mask filter material made of the melt-blown nonwoven fabric according to [1] or [2]. [Effects of the Invention]

[0010] According to the present invention, a melt-blown nonwoven fabric and a mask filter material having low pressure loss and high collection performance can be obtained. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic side view showing a measurement device for collection efficiency and pressure loss. DETAILED DESCRIPTION OF THE INVENTION

[0012] The meltblown nonwoven fabric of the present invention comprises primarily non-conductive fibers.

[0013] In the present invention, the non-conductive fiber is a fiber having a volume resistivity of 10 12 It refers to fibers with a volume resistivity of 10 Ω·cm or more. 12 Ω·cm or more, preferably 10 14 By having a resistivity of Ω·cm or more, a large amount of charge can be retained when converted into an electret, resulting in a melt-blown nonwoven fabric with excellent collection performance and low pressure loss.

[0014] Examples of resins that form the non-conductive fibers include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and polylactic acid, polycarbonate resins, polystyrene resins, polyphenylene sulfide resins, fluorine-based resins, elastomers such as polystyrene elastomers, polyolefin elastomers, polyester elastomers, polyamide elastomers and polyurethane elastomers, and copolymers or mixtures thereof.

[0015] Among these, polyolefin resins are preferably used. That is, the non-conductive fibers are preferably made of polyolefin resins. Polyolefin resins have high volume resistivity and low water absorption, so when made into fibers, they have strong charging and charge retention properties. Therefore, high collection efficiency can be achieved.

[0016] Examples of the polyolefin resin include homopolymers such as polyethylene, polypropylene, polybutene, and polymethylpentene. Copolymers obtained by copolymerizing different components with these homopolymers, and blends of two or more different polymers, can also be used. Among these, polypropylene and polymethylpentene are preferred from the viewpoint of charge retention. Polypropylene is more preferred from the viewpoints of low cost and ease of reducing the fiber diameter.

[0017] The non-conductive fibers may also contain additives such as stabilizers, weatherproofing agents, and polymerization inhibitors, as well as inorganic fillers and / or organic fillers, as long as the effects of the present invention are not impaired.

[0018] The non-conductive fiber may be a composite fiber, such as a core-sheath type, an eccentric core-sheath type, a side-by-side type, a split type, an island-in-the-sea type, or an alloy type.

[0019] The non-conductive fibers have an average fiber diameter of 1.0 μm or more and 3.0 μm or less. By making the average fiber diameter 1.0 μm or more, more preferably 1.5 μm or more, the strength of the melt-blown nonwoven fabric can be improved. On the other hand, by making the average fiber diameter 3.0 μm or less, the collection efficiency of the melt-blown nonwoven fabric can be improved.

[0020] To measure the average fiber diameter of the fibers that make up the meltblown nonwoven fabric, 15 3mm x 3mm measurement samples are taken from three points across the width of the nonwoven fabric (two side edges and one center point) and five points spaced 5cm apart in the longitudinal direction, for a total of 15 points. Then, using a scanning electron microscope (such as the Keyence VE-9800) at a magnification of 2000x, one photograph of the fiber surface is taken from each of the sampled measurement samples, for a total of 15 photographs. The fiber diameters of the fibers whose diameters (fiber diameters) can be clearly seen in the photographs are measured, and the average value is rounded to one decimal place.

[0021] The content of the non-conductive fibers in the meltblown nonwoven fabric is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 97% by mass or more, so that electret performance can be effectively obtained.

[0022] The meltblown nonwoven fabric contains a hindered amine compound.

[0023] Examples of the hindered amine compound include poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl)((2,2,6,6-tetramethyl-4-piperidyl)imino)hexamethylene((2,2,6,6-tetramethyl-4-piperidyl)imino)] (a commercially available product is Chimassorb (registered trademark) 944LD, manufactured by BASF Japan Ltd.), dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (a commercially available product is B Examples of such an amine include bis(1,2,2,6,6-pentamethyl-4-piperidyl) 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate (commercially available as TINUVIN (registered trademark) 144, manufactured by BASF Japan Ltd.), and a reaction product of N-butyl-1-butanamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine (commercially available as CHIMASSORB (registered trademark) 2020FDL, manufactured by BASF Japan Ltd.).

[0024] The content of the hindered amine compound in the meltblown nonwoven fabric is 0.1% by mass or more and 5.0% by mass or less. By having the content of the hindered amine compound be 0.1% by mass or more, preferably 0.7% by mass or more, excellent chargeability and charge retention properties can be obtained when the meltblown nonwoven fabric is subjected to electret processing. On the other hand, by having the content of the hindered amine compound be 5.0% by mass or less, preferably 3.0% by mass or less, it is possible to achieve the chargeability and charge retention properties at lower cost.

[0025] The content of hindered amine compounds can be determined as follows. Specifically, the nonwoven fabric is subjected to Soxhlet extraction with a methanol / chloroform mixed solution, and the extract is repeatedly fractionated by high-performance liquid chromatography (HPLC), and the structure of each fraction is confirmed. The structure can be confirmed by infrared absorption spectroscopy (IR), gas chromatography (GC), gas chromatography mass spectrometry (GC / MS), matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS), 1H-NMR measurement, and 13C-NMR measurement. The masses of the fractions containing hindered amine compounds are added together, and the percentage of the mass relative to the total mass of the nonwoven fabric is calculated. This is the hindered amine compound content.

[0026] The meltblown nonwoven fabric has a basis weight of 8 g / m 2 More than 18g / m 2 The weight is 8g / m 2 or more, preferably 10 g / m 2 By setting the weight to 18 g / m or more, the collection efficiency of the melt-blown nonwoven fabric can be improved. 2 or less, preferably 16 g / m 2 By setting the above as follows, the pressure loss of the melt-blown nonwoven fabric can be reduced.

[0027] The basis weight of meltblown nonwoven fabric is measured by taking a sample of 15cm length x 15cm width from the nonwoven fabric. The mass of the sample is measured and the value obtained is expressed as 1m 2 The value is converted to the unit weight of the meltblown nonwoven fabric (g / m2) and rounded off to the nearest whole number. 2 )

[0028] The meltblown nonwoven fabric has a formation index of 300 or more and 550 or less. A formation index of 300 or more, preferably 350 or more, can reduce pressure loss. On the other hand, a formation index of 550 or less, preferably 500 or less, more preferably 450 or less, can provide high collection performance.

[0029] The melt-blown nonwoven fabric is preferably electret-treated (charged), which can effectively improve collection efficiency.

[0030] The presence or absence of electret treatment can be determined by the state of adhesion of toner particles. A mixture of positively charged red toner particles and negatively charged blue toner particles is sprinkled onto electret-treated nonwoven fabric. After shaking off the excess toner particles that remain without static electricity, the nonwoven fabric is observed under a microscope (for example, Keyence VHX-8000).

[0031] A sample in which red and blue toner particles are separated and attached is determined to be electret, whereas a sample in which red and blue toner particles are mixed and attached, appearing purple, or a sample in which particles have fallen off and not attached, is determined to not be electret.

[0032] Next, a method for producing the melt-blown nonwoven fabric of the present invention will be described.

[0033] (Resin composition) The resin constituting the melt-blown nonwoven fabric of the present invention can be a commercially available resin, can be prepared by mixing the resin and the hindered amine compound at once, or can be prepared by chip blending a masterbatch of the resin and the hindered amine compound.

[0034] A method for mixing and preparing the resin and the hindered amine compound at once includes a method of extruding using a twin-screw extruder, etc. Note that it is also possible to compound other fillers together with the hindered amine compound to form a resin composition.

[0035] Furthermore, as a method for preparing a resin composition by chip blending a master batch of a resin and a hindered amine compound, for example, a master batch in which a hindered amine compound is kneaded into a resin at a high concentration is prepared, and the resin is chip blended with this and kneaded in an extruder. Hereinafter, the resin and the resin composition may be collectively referred to as a resin composition.

[0036] (meltblown nonwoven fabric) A melt-blown nonwoven fabric is formed from a resin composition. In the melt-blowing method, molten resin is extruded from a nozzle with a specified hole diameter to form threads. Hot air is sprayed at the extruded threads from a certain angle to thin the threads, and the threads are then deposited (collected) in a collection section to form a nonwoven fabric.

[0037] (electret treatment) As a method for electretizing a melt-blown nonwoven fabric, for example, a method in which a melt-blown nonwoven fabric is brought into contact with an earth electrode, and high voltage is applied with a non-contact application electrode while moving both the earth electrode and the melt-blown nonwoven fabric to continuously electretize it, a method in which a jet of water or a water droplet flow is sprayed onto the melt-blown nonwoven fabric with sufficient pressure to penetrate the interior of the melt-blown nonwoven fabric, thereby electretizing it and uniformly mixing positive and negative charges, or a method in which the melt-blown nonwoven fabric is passed over a slit-shaped nozzle and the water is sucked into the nozzle to penetrate the melt-blown nonwoven fabric, thereby uniformly mixing positive and negative charges (hydrocharge method), etc., can be used.

[0038] The melt-blown nonwoven fabric of the present invention has excellent collection performance and small pressure loss, so that when used as a filter material for a mask for hygiene products, it can reduce breathlessness when worn. That is, the mask filter material of the present invention is made of the melt-blown nonwoven fabric of the present invention. [Example]

[0039] The present invention will now be described in detail with reference to examples, although the present invention is not limited to these examples.

[0040] [Measurement method] (1) Average fiber diameter The average fiber diameter of the melt-blown nonwoven fabric was measured by the above-mentioned method using a scanning electron microscope, VE-9800 manufactured by Keyence Corporation.

[0041] (2) Thickness of meltblown nonwoven fabric Using a thickness meter (TECLOCK (registered trademark) SMD550 manufactured by TECLOCK Corporation), the thickness of the electret fiber sheet was measured at 10 points at equal intervals in the width direction, and the average value was rounded to three decimal places to obtain the thickness.

[0042] (3) Metsuke The basis weight of the meltblown nonwoven fabric was measured by the above-mentioned method.

[0043] (4) Collection efficiency and pressure loss The collection efficiency and pressure loss were measured and calculated using the following procedures. 1) Measurement samples M, each measuring 15 cm in length and 15 cm in width, were taken from five locations across the width of the fiber sheet of the laminated electret nonwoven fabric (a total of five samples). 2) In the collection efficiency measuring device shown in FIG. 1, the dust inlet 2 was opened to introduce air. 3) Place the measurement sample M in the sample holder 1, and adjust the airflow rate with the flow control valve 4 so that the filter passing speed is 1.5 m / min. The atmospheric dust concentration is set to 10,000 to 40,000 particles / 2.83 x 10 -4 m 3 It was confirmed that the above was stable. 4) A KC-01E particle counter manufactured by Rion Co., Ltd. was used. The number of dust particles D on the upstream side of the measurement sample M was measured using the upstream particle counter 6, and the number of dust particles d on the downstream side was measured using the downstream particle counter 7, three times per measurement sample. 5) Based on JIS K0901:1991 "Test methods for shape, dimensions and performance of filter media for collecting dust samples in gas," the collection efficiency (%) of 0.3 to 0.5 μm particles was calculated using the following formula. Collection efficiency (%) = [1-(d / D)] x 100 Here, d: Total number of downstream dust particles measured three times D: Total number of dust particles measured upstream three times. 6) In addition, the static pressure difference between the upstream and downstream sides of the measurement sample M was read using a pressure gauge 8, and the pressure loss (Pa) of the measurement sample M was calculated. 7) The average collection efficiency (%) for the five measurement samples M was calculated, and the value obtained by rounding off to three decimal places was taken as the collection efficiency (%) of the melt-blown nonwoven fabric. 8) The average value of the pressure loss (Pa) for the five measurement samples M was calculated, and the value obtained by rounding off to two decimal places was defined as the pressure loss (Pa) of the meltblown nonwoven fabric.

[0044] (5) Formation index The formation index was determined using a formation meter (Formation Tester FMT-4, manufactured by Nomura Shoji Co., Ltd.). A sample of meltblown nonwoven fabric was placed on a sample stage, and the transmitted image when light was irradiated from one side of the sample was captured with a CMOS camera. The entire image was divided into approximately 1.36 million pixels (1350 x 1012), and the light intensity received by each pixel was measured. The transmittance t for each pixel was calculated from the measured light intensity using the following formula. t=[(Vt-Vr) / (V 100 -V0)] × 100 Here, t: Absolute transmittance (%) Vt: The light intensity measured when the sample is placed and irradiated with LED light. Vr: The light intensity measured when the sample is placed and the LED light is turned off V 100 : The light intensity measured when the sample is removed and the LED light is irradiated. V0: The light intensity measured when the sample is removed and the LED light is turned off. The absorbance E was calculated from the obtained absolute transmittance t according to the following formula. E=(2-logt)×10000 The formation index was calculated from the absorbance E obtained using the following formula. Formation index = Coefficient of variation of absorbance E × 1000 = [Standard deviation of absorbance (σ)] / [Average value of absorbance (Eave.)].

[0045] [Example 1] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0046] (Resin composition) The resin composition used as the raw material was a polypropylene resin containing 1.0 mass % of a hindered amine compound, Chimassorb (registered trademark) 944 (manufactured by BASF Japan Ltd.), and having a melt flow rate of 850 g / 10 min.

[0047] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of a 0.30 mm diameter spinning nozzle set to 0.300 g / min. Air heated and compressed at a set temperature of 290°C was blown from both sides of the spinning nozzle at a rate of 1100 Nm 3 / hr and by adjusting the speed of the collector, the average basis weight is 10g / m 2 A melt-blown nonwoven fabric was obtained.

[0048] (electret treatment) Next, the obtained melt-blown nonwoven fabric was run along the water surface of a water tank to which pure water was supplied, and a slit-shaped suction nozzle was brought into contact with the surface to suck out the water, thereby allowing the water to penetrate the entire surface of the melt-blown nonwoven fabric. After draining the water, the fabric was dried with hot air at a temperature of 100°C to obtain an electret-treated melt-blown nonwoven fabric (electret melt-blown nonwoven fabric).

[0049] [Example 2] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0050] (Resin composition) The same resin composition as used in Example 1 was used.

[0051] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.480 g / min. Air heated and compressed at a set temperature of 290°C was blown from both sides of the spinning nozzle at a pressure of 1000 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 15g / m 2 A melt-blown nonwoven fabric was obtained.

[0052] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0053] [Example 3] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0054] (Resin composition) The same resin composition as used in Example 1 was used.

[0055] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.480 g / min. Air heated and compressed at a set temperature of 290°C was blown from both sides of the spinning nozzle at a pressure of 1000 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 18g / m 2 A melt-blown nonwoven fabric was obtained.

[0056] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0057] [Example 4] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0058] (Resin composition) The same resin composition as used in Example 1 was used.

[0059] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus described above, with the die temperature set to 298°C and the extrusion rate per hole of the spinning nozzle set to 0.161 g / min. Air heated and compressed at a set temperature of 298°C was blown from both sides of the spinning nozzle at a flow rate of 950 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 8g / m 2 A melt-blown nonwoven fabric was obtained.

[0060] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0061] [Example 5] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0062] (Resin composition) The same resin composition as used in Example 1 was used.

[0063] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus described above, with the die temperature set to 298°C and the extrusion rate per hole of the spinning nozzle set to 0.161 g / min. Air heated and compressed at a set temperature of 298°C was blown from both sides of the spinning nozzle at a flow rate of 950 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 10g / m 2 A melt-blown nonwoven fabric was obtained.

[0064] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0065] [Comparative Example 1] Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0066] (Resin composition) The same resin composition as used in Example 1 was used.

[0067] (meltblown nonwoven fabric) The polypropylene resin was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.480 g / min. Air heated and compressed at a set temperature of 290°C was blown from both sides of the spinning nozzle at a pressure of 1000 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 20g / m 2 A melt-blown nonwoven fabric was obtained.

[0068] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0069] Comparative Example 2 Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured from a polypropylene resin composition as a raw material.

[0070] (Resin composition) The same resin composition as used in Example 1 was used.

[0071] (meltblown nonwoven fabric) The polypropylene resin was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.480 g / min. Air heated and compressed at a set temperature of 285°C was blown from both sides of the spinning nozzle at a pressure of 950 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 15g / m 2 A melt-blown nonwoven fabric was obtained.

[0072] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0073] Comparative Example 3 Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured using polypropylene resin as a raw material.

[0074] (Resin composition) The same resin composition as used in Example 1 was used.

[0075] (meltblown nonwoven fabric) The resin composition was used in the manufacturing apparatus described above, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.397 g / min. Air heated and compressed at a set temperature of 254°C was blown from both sides of the spinning nozzle at a pressure of 1050 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 15g / m 2 A melt-blown nonwoven fabric was obtained.

[0076] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0077] Comparative Example 4 Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured using polypropylene resin as a raw material.

[0078] (resin) The raw material used was a polypropylene resin containing no hindered amine compounds and having a melt flow rate of 160 g / 10 min.

[0079] (meltblown nonwoven fabric) The polypropylene resin was used in the manufacturing apparatus, with the die temperature set to 290°C and the extrusion rate per hole of the spinning nozzle set to 0.397 g / min. Air heated and compressed at a set temperature of 254°C was blown from both sides of the spinning nozzle at a flow rate of 1150 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 15g / m 2 A melt-blown nonwoven fabric was obtained.

[0080] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0081] Comparative Example 5 Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured using polypropylene resin as a raw material.

[0082] (resin) The same resin composition as used in Example 1 was used.

[0083] (meltblown nonwoven fabric) The polypropylene resin was used in the manufacturing apparatus, with the die temperature set to 298°C and the extrusion rate per hole of the spinning nozzle set to 0.161 g / min. Air heated and compressed at a set temperature of 298°C was blown from both sides of the spinning nozzle at a pressure of 950 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 7g / m 2 A melt-blown nonwoven fabric was obtained.

[0084] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0085] Comparative Example 6 Using a melt-blown nonwoven fabric manufacturing apparatus, a melt-blown nonwoven fabric was manufactured using polypropylene resin as a raw material.

[0086] (resin) The same resin composition as used in Example 1 was used.

[0087] (meltblown nonwoven fabric) The polypropylene resin was used in the manufacturing apparatus, with the die temperature set to 265°C and the extrusion rate per hole of the spinning nozzle set to 0.017 g / min. Air heated and compressed at a set temperature of 265°C was blown from both sides of the spinning nozzle at a pressure of 700 Nm. 3 / hr and by adjusting the speed of the collector, the average basis weight is 15g / m 2 A melt-blown nonwoven fabric was obtained.

[0088] (electret treatment) The above melt-blown nonwoven fabric was subjected to electret treatment in the same manner as in Example 1 to obtain an electret melt-blown nonwoven fabric.

[0089] The physical properties of the obtained electret melt-blown nonwoven fabric were measured by the above-mentioned methods, and the results are shown in Table 1.

[0090] [Table 1] [Explanation of symbols]

[0091] 1: Sample holder 2: Dust inlet 3:Flow meter 4: Flow control valve 5: Blower 6: Upstream particle counter 7: Downstream particle counter 8: Pressure gauge M: Measurement sample

Claims

1. A melt-blown nonwoven fabric mainly comprising non-conductive fibers, the melt-blown nonwoven fabric containing 0.1% by mass or more and 5.0% by mass or less of a hindered amine compound, the non-conductive fibers having an average fiber diameter of 1.0 μm or more and 3.0 μm or less, and a basis weight of 8 g / m ２ 18g / m or more ２ A melt-blown nonwoven fabric having a texture index of 300 or more and 550 or less.

2. The meltblown nonwoven fabric according to claim 1, wherein the nonconductive fibers are made of a polyolefin resin.

3. A mask filter material comprising the melt-blown nonwoven fabric according to claim 1 or 2.

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