Fiber nonwoven fabric, filter, and method for producing fiber nonwoven fabric

Abstract

This fiber nonwoven fabric includes a fiber containing aromatic polyether ketone, wherein the coefficient of variation in the fiber diameter of the fiber is at most 100%.

Description

[Technical field]

[0001] The present invention relates to a fibrous nonwoven fabric, a filter, and a method for producing the fibrous nonwoven fabric. [Background technology]

[0002] Aromatic polyether ketones have a high melting point and excellent heat resistance, and therefore are sometimes used as nonwoven fabrics for filter media, battery separators, and the like.

[0003] For example, a heat-resistant melt-blown nonwoven fabric made of polyether ether ketone resin has an average fiber diameter of 1 to 20 μm and a basis weight of 5 to 120 g / m. 2 , air permeability is 1~400cc / cm 2 A melt-blown nonwoven fabric has been proposed that is characterized by having physical properties such as a fiber length of 100 mm / sec, a thickness of 0.05 to 1.0 mm, a tensile strength of 2 to 50 N / 25 mm, and a tensile elongation of 1 to 100% (see, for example, Patent Document 1).

[0004] Also proposed is a heat-resistant nonwoven fabric made of long fibers of aromatic polyether ketone, preferably having a fiber diameter of 3 to 50 μm and a crystallinity of 20 to 60%, and characterized in that the nonwoven fabric is integrated by thermocompression bonding with a bonding area ratio of 3% or more (see, for example, Patent Document 2). [Patent Document 1] JP 2008-81893 A [Patent Document 2] JP 2010-106388 A Summary of the Invention [Problem to be solved by the invention]

[0005] It has been found that the nonwoven fabrics made of polyether ether ketone resins described in Patent Documents 1 and 2 may have poor performance when used as filters. Filter performance is expressed, for example, as a quality factor (Q value). The Q value is a value calculated from the pressure loss and the particle collection efficiency.

[0006] When a nonwoven fabric is used as a filter, it is preferable that the Q value at room temperature is high and that the filter performance is maintained over a wide temperature range. Therefore, it is preferable that the Q value does not vary much even when the temperature changes, and it is desirable that the Q value does not decrease even after the filter is exposed to a high temperature. However, when a nonwoven fabric made of a thermoplastic resin is used as a filter, problems such as the thermoplastic resin constituting the nonwoven fabric melting when the filter is exposed to a high temperature, the Q value after the heat treatment is significantly lower than before the heat treatment, and the filter performance is deteriorated when the temperature changes, are likely to occur.

[0007] The present disclosure has been made in view of the above, and aims to provide a fibrous nonwoven fabric that has a high Q value at room temperature and is capable of suppressing a decrease in the Q value due to heat treatment, a filter including this fibrous nonwoven fabric, and a method for producing this fibrous nonwoven fabric. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> A fiber containing an aromatic polyether ketone, The fiber nonwoven fabric has a coefficient of variation of fiber diameter of 100% or less. <2> The viscosity of the fiber at 400°C is 50 Pa·s to 500 Pa·s. <1> The fiber nonwoven fabric described in claim 1. <3> The average fiber diameter of the fibers is 10 μm or less. <1> or <2> The fiber nonwoven fabric described in claim 1. <4> The aromatic polyether ketone comprises polyether ether ketone. <1> ~ <3> 13. The fiber nonwoven fabric according to claim 12 . <5> The fibrous nonwoven fabric includes a meltblown nonwoven fabric. <1> ~ <4> 13. The fiber nonwoven fabric according to claim 12 . <6> <1> ~ <5> A filter comprising the fibrous nonwoven fabric according to any one of claims 1 to 5. <7> The method includes a step of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or the resin composition by the heated gas to form a fibrous material, The flow rate of the heating gas is 150 Nm 3 / hour / m~1000Nm 3 / h / m, When the temperature of the heated gas is Ta (°C), the temperature of the molten resin or the resin composition is Tp (°C), the crystallization temperature of the aromatic polyether ketone is Tc (°C), and the melting point of the aromatic polyether ketone is Tm (°C), the discharge of the heated gas is performed so as to satisfy the following formulas (1) and (2): Formula (1) Tc <Ta≦Tm+200 Formula (2) 40≦Tp-Ta≦190 <8> The viscosity of the resin or the resin composition at 400°C is 50 Pa·s to 500 Pa·s. <7> A method for producing the fibrous nonwoven fabric according to claim 1. <9> The heated gas is discharged so as to further satisfy the following formula (1)': <7> or <8> A method for producing the fibrous nonwoven fabric according to claim 1. Formula (1)' Tm-30≦Ta≦Tm+200 <10> The flow rate of the heating gas is 250 Nm 3 / hour / m~850Nm 3 / h / m <7> ~ <9> 13. A method for producing a fibrous nonwoven fabric according to any one of claims 1 to 12. <11> A method for producing a fibrous nonwoven fabric, comprising the steps of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or resin composition with the heated gas while cooling the resin or resin composition with cooling gas supplied from both sides in the machine direction to form a fibrous material. Formula (3) 300℃≦Tp-Tq≦550℃ <12> The flow rate of the cooling gas is 1000 Nm 3 / hour / m~20000Nm 3 / h / m <11> A method for producing the fibrous nonwoven fabric according to claim 1. <13> The temperature of the cooling gas is 30° C. or less. <11> or <12> A method for producing the fibrous nonwoven fabric according to claim 1. <14> When the temperature of the molten resin or the resin composition is Tp (°C) and the temperature of the cooling gas is Tq (°C), the discharge of the heating gas and the supply of the cooling gas satisfy the following formula (3): <11> ~ <13> 13. A method for producing a fibrous nonwoven fabric according to any one of claims 1 to 12. Formula (3) 350℃≦Tp-Tq≦550℃ <15> The aromatic polyether ketone comprises polyether ether ketone. <7> ~ <14> 13. A method for producing a fibrous nonwoven fabric according to any one of claims 1 to 12. <16> The resin or resin composition containing the aromatic polyether ketone is melted using a twin-screw extruder. <11> ~ <15> 13. A method for producing a fibrous nonwoven fabric according to any one of claims 1 to 12. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a fibrous nonwoven fabric that has a high Q value at room temperature and is capable of suppressing a decrease in the Q value due to heat treatment, a filter including this fibrous nonwoven fabric, and a method for producing this fibrous nonwoven fabric. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a fibrous nonwoven fabric production apparatus used in the fibrous nonwoven fabric production method 1 of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of a fibrous nonwoven fabric production apparatus used in the fibrous nonwoven fabric production method 2 of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the present disclosure, the use of "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower limit and upper limit. In the present disclosure, in the ranges of numerical values ​​described stepwise, the upper limit or lower limit of one numerical range may be replaced with the upper limit or lower limit of another numerical range of numerical values ​​described stepwise. In addition, in the ranges of numerical values ​​described in the present disclosure, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. In the present disclosure, the term "step" refers not only to an independent step, but also to a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In this disclosure, when referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, it means the total amount of multiple substances present in the composition, unless otherwise specified.

[0012] In the present disclosure, the Q value of a fibrous nonwoven fabric is a value calculated by the following formula (a) using the collection efficiency and pressure loss. As shown in the formula below, the lower the pressure loss and the higher the collection performance, the higher the Q value, and it can be seen that the filtration performance is good when the fibrous nonwoven fabric is used as a filter. Q value (Pa -1 ) = -[ln(1-[Collection efficiency]) / (Pressure loss (Pa))] (a)

[0013] In the present disclosure, the collection efficiency and pressure loss can be measured by the method described in the Examples below.

[0014] Average fiber diameter d of the fibers constituting the fibrous nonwoven fabric f Collection efficiency Y(d f )(-) is represented by the following formula (b) as described in Russell, Stephen J. Handbook of nonwovens. Woodhead Publishing, p. 488, 2006. In the following formula (b), Y(d f ) is the average fiber diameter d f Collection efficiency at d f is the average fiber diameter (m), Φ is the volume fraction occupied by the fibrous nonwoven fabric (-), h is the thickness of the fibrous nonwoven fabric (m), E is the collection capacity per standard unit area for the flow perpendicular to the fibrous nonwoven fabric (-), ef represents the effective fiber length coefficient (-).

[0015]

number

[0016] Average fiber diameter d of the fibers constituting the fibrous nonwoven fabric f The pressure loss ΔP0 (Pa) at the fiber is expressed by the following formula (c) as described in Russell, Stephen J. Handbook of nonwovens. Woodhead Publishing, p. 488, 2006. In the following formula (c), ΔP0 is the average fiber diameter d f Pressure loss at (Pa), d f is the average fiber diameter (m), Φ is the volume fraction occupied by the fibrous nonwoven fabric (-), h is the thickness of the fibrous nonwoven fabric (m), η is the fluid viscosity (Pa s), and U0 is the fluid velocity (m / s).

[0017]

number

[0018] In the present disclosure, a fibrous nonwoven fabric having a superior Q value compared to another fibrous nonwoven fabric means that the Q value is higher when the average fiber diameter is converted to the same value, for example, an average fiber diameter of 5 μm.

[0019] Substituting the measured collection efficiency, the measured average fiber diameter, the volume fraction of the fibrous nonwoven fabric, and the thickness of the fibrous nonwoven fabric into equation (b), E / e f Next, the volume fraction of the fibrous nonwoven fabric, the thickness of the fibrous nonwoven fabric, and the calculated E / e f Substituting into formula (b), and further, the average fiber diameter d f as 5×10 -6 By substituting the value of m (5 μm) into equation (b), the collection efficiency when converted to an average fiber diameter of 5 μm can be calculated. By substituting the measured pressure loss, the measured average fiber diameter, the volume fraction of the fibrous nonwoven fabric, and the thickness of the fibrous nonwoven fabric into formula (c), U0η can be calculated. Next, the volume fraction of the fibrous nonwoven fabric, the thickness of the fibrous nonwoven fabric, and the calculated U0η are substituted into formula (c), and the average fiber diameter d f as 5×10 -6 By substituting the value of m (5 μm) into equation (c), the pressure loss when the average fiber diameter is converted to 5 μm can be calculated. The Q value when the average fiber diameter is converted to 5 μm can be calculated by substituting the collection efficiency when the average fiber diameter is converted to 5 μm and the pressure loss when the average fiber diameter is converted to 5 μm into equation (a).

[0020] [Nonwoven fiber fabric] The fibrous nonwoven fabric of the present disclosure includes fibers containing aromatic polyether ketone, and the fiber diameter coefficient of variation of the fibers is 100% or less. As a result, the fibrous nonwoven fabric of the present disclosure has a suppressed variation in fiber diameter, and therefore a filter formed using the fibrous nonwoven fabric has excellent collection efficiency. More specifically, a filter formed using the fibrous nonwoven fabric of the present disclosure not only has a high Q value at room temperature, but also maintains filter performance over a wide temperature range. Furthermore, even after the filter is exposed to a high temperature of about 250°C, a decrease in the Q value is suppressed. In addition, in a filter formed using the fibrous nonwoven fabric of the present disclosure, the difference between the Q value at room temperature and the Q value at room temperature after exposure to a high temperature is small, and the variation in the Q value is suppressed over a wide temperature range, and the fibrous nonwoven fabric of the present disclosure tends to have excellent performance retention.

[0021] In the fibrous nonwoven fabric of the present disclosure, from the viewpoint of suppressing spinning defects and reducing the average fiber diameter, the viscosity of the fibers at 400°C is preferably 50 Pa·s to 500 Pa·s, more preferably 60 Pa·s to 250 Pa·s, and even more preferably 70 Pa·s to 95 Pa·s. The method for measuring viscosity in the present disclosure is as described in the Examples below.

[0022] The average fiber diameter of the fibers constituting the fibrous nonwoven fabric of the present disclosure is preferably 10 μm or less, from the viewpoint of enabling a filter formed using the fibrous nonwoven fabric to effectively capture smaller particles, and from the viewpoints of the strength and collection efficiency of the fibrous nonwoven fabric, is more preferably 0.1 μm to 10 μm, even more preferably 0.3 μm to 8.0 μm, and particularly preferably 0.5 μm to 5.0 μm.

[0023] The average fiber diameter of the fibers constituting the fibrous nonwoven fabric can be determined as follows: An electron microscope photograph (magnification 1000 times) of the fibrous nonwoven fabric is taken, and the diameters of the fibers that can be measured from the obtained photograph are measured, and the photographing and measurement are repeated until the total number of fibers measured exceeds 100, and the arithmetic mean value of the obtained fiber diameters is defined as the aforementioned average fiber diameter.

[0024] The coefficient of variation (CV value) of the fiber diameter of the fibers constituting the fibrous nonwoven fabric of the present disclosure is 100% or less, and from the viewpoint of the collection efficiency formed using the fibrous nonwoven fabric, it is preferably 90% or less, and more preferably 85% or less. The CV value is not particularly limited as long as it is 0% or more, and may be, for example, 30% or more, or 50% or more. The CV value can be calculated by multiplying the value obtained by dividing the standard deviation (Dp) of the measurement result of the average fiber diameter by the average fiber diameter (Da) by 100 (see the following formula). CV value = [standard deviation (Dp) / average fiber diameter (Da)] x 100

[0025] Fiber nonwoven fabric hole weight 10g / m 2The average pore size measured by is preferably 0.01 μm to 10.0 μm, more preferably 0.1 μm to 3.0 μm. When the average pore size is 0.01 μm or more, when the fibrous nonwoven fabric is used as a filter, the pressure loss is not too high and the decrease in flow rate is easily suppressed. When the average pore size is 10.0 μm or less, when the fibrous nonwoven fabric is used as a filter, the collection efficiency tends to be improved. The average pore size of the fibrous nonwoven fabric can be measured by the bubble point method. Specifically, a test piece of the fibrous nonwoven fabric is impregnated with a fluorine-based inert liquid, and the pore size is measured by a capillary flow porometer.

[0026] The basis weight of the fibrous nonwoven fabric may be appropriately determined depending on the application. For example, 2 ~200g / m 2 It is preferable that the thickness is 5 g / m 2 ~100g / m 2 It is more preferable that the basis weight is 1 g / m 2 When the fiber weight is 200 g / m or more, the strength of the fibrous nonwoven fabric is improved and the fabrication becomes easier. 2 If it is equal to or less than this, the pressure loss will not be too high and there is a tendency that it can be suitably used as a filter. The method for measuring the basis weight of the fibrous nonwoven fabric in the present disclosure is as described in the Examples below.

[0027] The thickness of the fibrous nonwoven fabric may be appropriately determined depending on the application, and is preferably 0.01 mm to 1.00 mm, and more preferably 0.05 mm to 0.60 mm. When the thickness is 0.01 mm or more, the balance between the dust collection efficiency and the pressure loss is preferably ensured when the fabricated filter is used, and the Q value of the filter tends to be improved, and when the thickness is 1.00 mm or less, the thickness of the filter tends to be thin, and this is preferable. According to the fibrous nonwoven fabric of the present disclosure, the collection efficiency is improved by suppressing the variation in fiber diameter, and therefore the Q value tends to be excellent even when the thickness is thin compared to conventional fibrous nonwoven fabrics. The method for measuring the thickness of the fibrous nonwoven fabric in the present disclosure is as described in the Examples below.

[0028] The air permeability of the fibrous nonwoven fabric can be determined appropriately depending on the application. For example, 3 / cm 2 / sec~200cm 3 / cm 2 / sec is preferably 1.0 cm 3 / cm 2 / sec~150cm 3 / cm 2 It is more preferable that the air permeability is 0.1 cm / sec. 3 / cm 2 / sec or more, the pressure loss tends to be lower, and the air permeability is 200 cm 3 / cm 2 / sec or less, the collection efficiency tends to be improved. The method for measuring the air permeability of the fibrous nonwoven fabric in the present disclosure is as described in the Examples below.

[0029] The fibrous nonwoven fabric of the present disclosure is not particularly limited as long as it contains at least one type of nonwoven fabric. Examples of nonwoven fabrics contained in the fibrous nonwoven fabric of the present disclosure include meltblown nonwoven fabrics, spunbond nonwoven fabrics, wet nonwoven fabrics, spunlace nonwoven fabrics, dry nonwoven fabrics, dry pulp nonwoven fabrics, airlaid nonwoven fabrics, waterjet nonwoven fabrics, flash spun nonwoven fabrics, open fiber nonwoven fabrics, needle punch nonwoven fabrics, and various other known short fiber nonwoven fabrics and long fiber nonwoven fabrics (e.g. long fiber cellulose nonwoven fabrics). Among these, the fibrous nonwoven fabric of the present disclosure preferably contains a meltblown nonwoven fabric. The fibrous nonwoven fabric of the present disclosure may be composed of one type of nonwoven fabric, or may be composed of two or more types of nonwoven fabric.

[0030] The fibrous nonwoven fabric of the present disclosure may be used as a single-layer nonwoven fabric, or may be used as a nonwoven fabric constituting at least one layer of a laminate. Examples of other layers constituting the laminated nonwoven fabric include, in addition to the fibrous nonwoven fabric of the present disclosure, other nonwoven fabrics such as conventional meltblown nonwoven fabrics, spunbonded nonwoven fabrics, needlepunched nonwoven fabrics, and spunlace nonwoven fabrics, woven fabrics, knitted fabrics, and paper.

[0031] The fibrous nonwoven fabric of the present disclosure can be used in a wide range of applications for which fibrous nonwoven fabrics are typically used, including, for example, filters, sanitary materials, medical materials, packaging materials, battery separators, heat retaining materials, insulating materials, protective clothing, clothing materials, electronic materials, and sound absorbing materials.

[0032] The fibrous nonwoven fabric of the present disclosure can be preferably used as a filter such as a gas filter (air filter) or a liquid filter. The fibrous nonwoven fabric of the present disclosure has a small variation in the CV value, i.e., the fiber diameter, and therefore is less likely to form relatively large holes (missing areas) between the fibers. As a result, the fibrous nonwoven fabric of the present disclosure is preferably used for a high-performance filter with excellent filtration performance.

[0033] The fibrous nonwoven fabric of the present disclosure may be electrically charged. The electrically charged fibrous nonwoven fabric is preferably used for an air filter. The electrically charged fibrous nonwoven fabric is obtained by subjecting the fibrous nonwoven fabric before charging to an electrostatic charging process as described below.

[0034] The fibers contained in the fibrous nonwoven fabric of the present disclosure contain aromatic polyetherketone. The aromatic polyetherketone is not particularly limited as long as it is a polymer having a structure having an aromatic ring such as a benzene ring, an ether bond, and an aromatic ring such as a benzene ring in this order, and a structure having an aromatic ring such as a benzene ring, a ketone bond, and an aromatic ring such as a benzene ring in this order. In addition, the aromatic polyetherketone may further have a skeleton other than the aromatic ring, the ether bond, and the ketone bond, such as an ester bond.

[0035] Specific examples of aromatic polyether ketones include polyether ketone, polyether ketone ketone, polyether ether ketone ketone, polyether ketone ester, and the like, and from the viewpoint of heat resistance, polyether ether ketone is preferred. The above-mentioned fibers may contain one type of aromatic polyetherketone, or may contain two or more types of aromatic polyetherketone.

[0036] The fibers may contain only aromatic polyetherketone as a resin, or may contain aromatic polyetherketone and other resins, such as thermoplastic resins.

[0037] From the viewpoint of heat resistance, the content of aromatic polyether ketone in the resin contained in the above-mentioned fibers is preferably 50 mass% or more, more preferably 90 mass% or more, and even more preferably 99 mass% or more, based on the total amount of the resin. The upper limit of the content of aromatic polyether ketone in the resin contained in the above-mentioned fibers is not particularly limited.

[0038] The thermoplastic resin that can be contained in the above-mentioned fiber is not particularly limited, and examples thereof include homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide, polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, and ionomers. The thermoplastic resin may be one type or a mixture of two or more types.

[0039] Examples of α-olefin homopolymers or copolymers include ethylene-based polymers such as ethylene random copolymers, such as ethylene-propylene random copolymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, and ethylene-1-butene random copolymers; propylene-based polymers such as propylene random copolymers, such as polypropylene (propylene homopolymer), propylene-ethylene random copolymer, and propylene-1-butene random copolymer; poly-1-butene, poly-4-methyl-1-pentene, etc.

[0040] The fibers contained in the fibrous nonwoven fabric of the present disclosure may contain commonly used additives as necessary, such as various known additives, such as antioxidants, weathering stabilizers, heat stabilizers, light stabilizers, antistatic agents, antifogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, and waxes.

[0041] From the viewpoint of heat resistance, the content of aromatic polyether ketone in the above-mentioned fibers is preferably 50% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more, based on the total amount of the fibers. The upper limit of the content of the aromatic polyether ketone in the above-mentioned fiber is not particularly limited.

[0042] As examples of the method for producing the fibrous nonwoven fabric of the present disclosure, a fibrous nonwoven fabric production method 1 and a fibrous nonwoven fabric production method 2 will be described below. The method for producing the fibrous nonwoven fabric of the present disclosure is not limited to these production methods.

[0043] [Method of manufacturing fibrous nonwoven fabric 1] The method for producing a fibrous nonwoven fabric according to the present disclosure includes a step of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or the resin composition with the heated gas to form a fibrous material, and the flow rate of the heated gas is set to 150 Nm 3 / hour / m~1000Nm 3 / hour / m, the temperature of the heated gas is Ta (°C), the temperature of the molten resin or the resin composition is Tp (°C), the crystallization temperature of the aromatic polyether ketone is Tc (°C), and the melting point of the aromatic polyether ketone is Tm (°C), the method is such that the discharge of the heated gas satisfies the following formulas (1) and (2): Formula (1) Tc <Ta≦Tm+200 Formula (2) 40≦Tp-Ta≦190

[0044] Conventionally, for example, as described in Republished Patent No. 2012 / 102398, the temperature (Ta) of the heating gas is generally set to be equal to or higher than the temperature (spinneret temperature) (Tp) of the molten resin or resin composition. In contrast, the present inventors have found that the above-mentioned fibrous nonwoven fabric with small variation in fiber diameter can be produced by setting the temperature (Ta) of the heating gas to a certain level lower than the temperature (Tp) of the molten resin or resin composition and controlling the flow rate of the heating gas within a predetermined range.

[0045] The reason for this is not clear, but is presumed to be as follows. That is, when Tp-Ta (ΔT) is 40°C or more, the resin or resin composition discharged from the spinneret is moderately quenched, and therefore tends to be moderately solidified. As a result, the resin or resin composition discharged in a fibrous form is less likely to fuse to each other, and the variation in fiber diameter can be reduced. On the other hand, when ΔT is 190°C or less and the temperature (Ta) of the heated gas satisfies the range of formula (1), the resin or resin composition discharged from the spinneret is not cooled too rapidly, and the drawing (pulling) effect of the heated gas is less likely to be impaired. As a result, insufficient drawing by the heated gas can be suppressed, and an increase in fiber diameter can also be suppressed. Furthermore, by adjusting the flow rate of the heated gas, the stretching effect can be fully exerted, and the increase in fiber diameter can be suppressed, and the variation in fiber diameter caused by the fusion of adjacent fibrous resins or resin compositions immediately after discharge can also be suppressed. According to the manufacturing method 1 of the fibrous nonwoven fabric of the present disclosure, a fibrous nonwoven fabric having a high Q value at room temperature when used as a filter and capable of suppressing a decrease in the Q value due to heat treatment can be produced. Furthermore, in a filter formed using the fibrous nonwoven fabric manufactured by the manufacturing method 1 of the fibrous nonwoven fabric of the present disclosure, the difference between the Q value at room temperature and the Q value at room temperature after exposure to high temperatures is small, and the fluctuation of the Q value is suppressed over a wide temperature range, and the fibrous nonwoven fabric tends to have excellent performance retention.

[0046] In the manufacturing method 1 of the fibrous nonwoven fabric of the present disclosure, from the viewpoint of obtaining a fibrous nonwoven fabric with small variation in fiber diameter, there is no need to separately spray a cooling gas for quenching the resin or resin composition discharged from the spinneret, and for example, there is no need to perform an additional step of spraying a cooling gas of 30°C or less onto the resin or resin composition discharged from the spinneret. In other words, there is no need to perform gas spraying in multiple stages, but it can be performed in one stage. Furthermore, as described in Republished Patent No. 2012 / 102398, in order to reduce the variation in fiber diameter, there is no need to arrange a suction hood along the outer peripheral surface of a suction roll, a suction belt, etc., or to control the airflow with a suction hood. Therefore, the manufacturing method 1 of the fibrous nonwoven fabric of the present disclosure can be realized with a relatively simple device configuration.

[0047] A method 1 for producing a fibrous nonwoven fabric according to the present disclosure includes a step of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with heated gas by a melt blowing method, and stretching the resin or resin composition with the heated gas to form a fibrous material.

[0048] The melt-blown method is a method in which, when a molten resin or resin composition is discharged from a spinneret in a fibrous form, heated gas is applied from both sides of the molten discharged material (discharged resin or resin composition) and the diameter of the discharged material is reduced by accompanying the heated gas. Specifically, for example, a resin containing aromatic polyether ketone or a resin composition containing aromatic polyether ketone and at least one of other resins and additives as a raw material is melted using an extruder or the like. The molten resin or resin composition is introduced into a spinneret connected to the tip of the extruder and discharged in a fibrous form from the spinning nozzle of the spinneret. The resin or resin composition discharged in a fibrous form is applied with heated gas ejected from the gas nozzle of the spinneret, and the resin or resin composition is stretched by the heated gas, thereby thinning the resin or resin composition.

[0049] The preferred conditions for the content of the aromatic polyether ketone in the resin are the same as those for the content of the aromatic polyether ketone in the resin contained in the fiber. The preferable condition for the lower limit of the content of the aromatic polyether ketone contained in the resin composition is the same as the preferable condition for the content of the aromatic polyether ketone in the fiber. The upper limit of the content of the aromatic polyether ketone contained in the resin composition is not particularly limited as long as it is less than 100 mass%. From the viewpoint of heat resistance, the aromatic polyether ketone contained in the resin or the resin composition preferably contains polyether ether ketone.

[0050] The viscosity of the resin or resin composition at 400°C is preferably 50 Pa·s to 500 Pa·s, more preferably 70 Pa·s to 260 Pa·s, and even more preferably 80 Pa·s to 105 Pa·s, from the viewpoint of excellent spinning stability of the resin or resin composition and of easy spinning to thereby produce fibers having a small average fiber diameter. The resin and resin composition to be measured for viscosity refer to the resin and resin composition before melting.

[0051] As described above, in order to reduce the diameter of the fibers constituting the fibrous nonwoven fabric and to reduce the variation in fiber diameter (narrow the fiber diameter distribution), the heated gas is blown so as to satisfy the following formulas (1) and (2). Formula (1) Tc <Ta≦Tm+200 Formula (2) 40≦Tp-Ta≦190

[0052] As shown in formula (1), when the temperature (Ta) of the heated gas is higher than the crystallization temperature (Tc), poor stretching caused by solidification of the discharged resin or resin composition can be suppressed, and an increase in fiber diameter can be suppressed. When the temperature (Ta) of the heated gas is Tm+200°C or less, not only is it easy to adjust ΔT (Tp-Ta) to the above range, but also it is possible to suppress thread breakage caused by a decrease in the melt viscosity of the discharged resin or resin composition. In particular, from the viewpoint of sufficiently stretching the discharged resin or resin composition to easily obtain fibers with a smaller fiber diameter, it is more preferable that the temperature (Ta) of the heated gas satisfies the following formula (1)'. Formula (1)' Tm-30≦Ta≦Tm+200

[0053] From the viewpoint of a balance between suppressing the variation in fiber diameter and suppressing the increase in fiber diameter, Tp-Ta (ΔT) is preferably 40° C. to 180° C., and more preferably 80° C. to 140° C. If ΔT is 40° C. or more, the average fiber diameter tends to be smaller, which is preferable.

[0054] The temperature (Ta) of the heating gas may be selected according to the type of aromatic polyetherketone so as to satisfy the above formula (1), and preferably also to satisfy formula (1)'. When the aromatic polyetherketone is polyetheretherketone, the temperature (Ta) of the heating gas is, for example, preferably 300°C to 500°C, more preferably 320°C to 480°C, and further preferably 340°C to 440°C.

[0055] The temperature (Tp) of the molten resin or resin composition may be selected according to the type of aromatic polyether ketone so as to satisfy the above-mentioned formula (2). When the aromatic polyether ketone is polyether ether ketone, the temperature (Tp) of the molten resin composition is, for example, preferably 360°C to 520°C, more preferably 400°C to 490°C, and further preferably 460°C to 490°C.

[0056] The temperature (Tp) of the molten resin or resin composition can be measured as the set temperature of the spinneret (die). The temperature (Ta) of the heated gas can be measured as the temperature of the heated gas immediately after it is discharged from the spinneret (die). Specifically, the temperature (Ta) of the heated gas can be measured as the temperature of the heated gas at the opening of the gas nozzle of the spinneret (die). The temperature (Ta) of the heated gas may be adjusted, for example, by measuring the temperature (Ta) of the heated gas at the opening of the gas nozzle of the spinneret (die) and adjusting the supply temperature of the heated gas so that the temperature (Ta) of the heated gas at the opening of the gas nozzle is a predetermined temperature; or, under predetermined conditions (e.g., die temperature, heated gas flow rate), data (calibration curve) showing the relationship between the temperature (Ta) of the heated gas at the opening of the gas nozzle and the supply temperature of the heated gas is prepared in advance, and the supply temperature of the heated gas is adjusted based on the data so that the temperature (Ta) of the heated gas at the opening of the gas nozzle is a predetermined temperature.

[0057] The crystallization temperature (Tc) and melting point (Tm) of the aromatic polyether ketone can be measured using DSC (differential scanning calorimetry). Specifically, a differential scanning calorimeter (DSC) manufactured by PerkinElmer, Inc. was used. Using an is1 or SII NanoTechnology DSC7020, heat the sample (approximately 5 mg) to the target temperature set for each aromatic polyether ketone (490 °C for polyether ether ketone) under a nitrogen atmosphere (20 mL / min), hold the sample at that temperature for 3 minutes, then cool the sample at 10 °C / min to 30 °C, hold the sample at 30 °C for 1 minute, and heat the sample at 10 °C / min to the target temperature. Calculate the melting point (Tm) from the peak apex of the crystal melting peak during the heating process, and calculate the crystallization temperature (Tc) from the peak apex of the crystallization peak during the cooling process. If multiple crystal melting peaks are observed, the peak on the higher temperature side is taken as the melting point (Tm).

[0058] The discharge rate of the resin composition per spinning nozzle of the spinneret is usually 0.01 g / min to 3.0 g / min, preferably 0.05 g / min to 2.0 g / min. When the discharge rate is 0.01 g / min or more, not only is the productivity of the fibrous nonwoven fabric not easily impaired, but also fiber breakage is easily suppressed. When the discharge rate is 3.0 g / min or less, the fiber diameter is easily made sufficiently small.

[0059] The flow rate of the heated gas is set to 150 Nm3 from the viewpoint of reducing the diameter of the fibers constituting the fibrous nonwoven fabric and reducing the variation in the diameter of the fibers (narrowing the fiber diameter distribution). 3 / hour / m~1000Nm 3 / h / m. The flow rate of the heating gas is 150Nm 3 When the flow rate of the heated gas is 1000 Nm / hr / m or more, the discharged resin composition can be sufficiently stretched and the fiber diameter can be sufficiently reduced. 3 If the flow rate of the heating gas is less than 250 Nm / hr / m, it is easy to suppress the increase in the variation in fiber diameter caused by the turbulence of the air flow. 3 / hour / m~850Nm 3 / hour / m is preferred.

[0060] The type of heating gas is not particularly limited, and examples thereof include gases inert to the molten resin or resin composition, such as air, carbon dioxide gas, nitrogen gas, etc. Among these, air is preferred from the viewpoint of economy.

[0061] The discharged resin or resin composition is stretched by heated gas to obtain a fibrous material. The average fiber diameter of the fibrous material is preferably 10 μm or less from the viewpoint of the filter formed using the produced fibrous nonwoven fabric suitably capturing smaller particles, and is more preferably 0.1 μm to 10 μm, further preferably 0.3 μm to 8.0 μm, and particularly preferably 0.5 μm to 5.0 μm from the viewpoint of the strength and collection efficiency of the fibrous nonwoven fabric. The method for measuring the average fiber diameter of the fibrous material is the same as the method for measuring the average fiber diameter of the fibers described above.

[0062] The method for producing a fibrous nonwoven fabric according to the present disclosure may further include a step of collecting the fibrous material in a web form after the step of forming the fibrous material. In this collecting step, the obtained fibrous material is collected in a web form on a collector, for example. When collecting the fibrous material on the collector, the collection may be promoted by sucking air from the back side of the collector as viewed from the fibers.

[0063] Specific examples of the collector include a perforated belt, a perforated drum, etc. The collection of fibrous materials may be promoted by, for example, sucking air from the rear side of the collector.

[0064] The thinned fibers may be collected on a desired substrate that is previously provided on a collector. Examples of the substrate that may be previously provided include meltblown nonwoven fabrics, spunbond nonwoven fabrics, needle punched and spunlace nonwoven fabrics, and other nonwoven fabrics, woven fabrics, knitted fabrics, and paper. This allows the production of ultrafine fiber nonwoven fabric laminates for use in high-performance filters, wipers, and the like.

[0065] A fibrous nonwoven fabric manufacturing apparatus used in the fibrous nonwoven fabric manufacturing method 1 of the present disclosure will be described with reference to FIG.

[0066] 1 is a schematic diagram showing an example of the configuration of a fibrous nonwoven fabric production apparatus 10. As shown in FIG. 1, the fibrous nonwoven fabric production apparatus 10 has an extruder 20, a die (spinneret) 30, and a collection mechanism 40.

[0067] The extruder 20 has a hopper 21 and a compression section 22. The extruder 20 melts the solid resin or resin composition fed into the hopper 21 in the compression section 22. The extruder 20 may be a single-screw extruder or a multi-screw extruder such as a twin-screw extruder. From the viewpoint of improving spinning stability, it is preferable to melt the resin or resin composition using a twin-screw extruder.

[0068] The die (spinning nozzle) 30 is disposed connected to the tip of the extruder 20. The die 30 has a plurality of spinning nozzles 31 and two gas nozzles 32.

[0069] A plurality of spinning nozzles 31 are usually arranged in a row. The spinning nozzle 31 receives the molten resin or resin composition conveyed from the extruder 20 and extrudes the resin or resin composition in a fibrous form from the nozzle opening. The diameter of the spinning nozzle may be, for example, 0.05 mm to 0.80 mm. The temperature (Tp) of the molten resin or resin composition can be adjusted by the set temperature of the die 30.

[0070] The distance between small holes in the spinning nozzle of the spinneret is preferably 0.1 mm to 2.0 mm, and more preferably 0.15 mm to 1.8 mm. When the distance between small holes is 0.1 mm or more, the variation in fiber diameter tends to be reduced. When the distance between small holes is 2.0 mm or less, the production efficiency tends to be improved.

[0071] The two gas nozzles (air nozzles) 32 are disposed near the nozzle opening of the spinning nozzle 31, specifically, on both sides of the row of the multiple spinning nozzles 31. The gas nozzles 32 inject heated gas (heated compressed gas) near the opening of the spinning nozzle 31. As shown in FIG. 1, the gas nozzles 32 inject heated gas into the resin or resin composition immediately after it is discharged from the opening of the spinning nozzle 31.

[0072] The heating gas supplied to the gas nozzle 32 is supplied from a gas heating device 50. The temperature (Ta) of the heating gas can be adjusted by a heating temperature adjustment means (not shown) attached to the gas heating device 50.

[0073] The collecting mechanism 40 has a porous belt (collector) 41, rollers 42 and 42 that support and transport the porous belt 41, and an air suction unit 43 arranged on the back side of the collecting surface of the porous belt 41. The air suction unit 43 is connected to a blower 44. The collecting mechanism 40 collects the obtained fibrous material on the moving porous belt 41.

[0074] According to this configuration, the resin or resin composition melted in the extruder 20 is introduced into the spinning nozzle 31 of the die (spinneret) 30 and discharged from the opening of the spinning nozzle 31. Meanwhile, heated gas is sprayed from the gas nozzle 32 toward the vicinity of the opening of the spinning nozzle 31. The discharged resin or resin composition is then stretched and thinned by the heated gas to become a fibrous material.

[0075] The temperature (Ta) of the heated gas is adjusted to satisfy the above-mentioned formulas (1) and (2). As a result, the molten resin or resin composition is appropriately quenched and stretched. The flow rate of the heated gas is adjusted to satisfy the above-mentioned range. As a result, even if the molten resin or resin composition is quenched, it can be sufficiently stretched. Therefore, it is possible to reduce the fiber diameter while reducing the variation in fiber diameter. The discharged fibrous material is collected on the perforated belt 41, and a fibrous nonwoven fabric is obtained.

[0076] [Method of manufacturing fibrous nonwoven fabric 2] The manufacturing method 2 of the fibrous nonwoven fabric disclosed herein includes a step of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or resin composition by the heated gas while cooling the resin or resin composition with cooling gas supplied from both sides in the machine direction to form a fibrous material.

[0077] The manufacturing method 2 of the fibrous nonwoven fabric of the present disclosure differs from the manufacturing method 1 of the fibrous nonwoven fabric of the present disclosure in that the discharge of the heated gas is not limited to a method that satisfies the above formulas (1) and (2), and that when the resin or resin composition is stretched by the heated gas, the resin or resin composition is cooled by the cooling gas supplied from both sides in the machine direction. In the manufacturing method 2 of the fibrous nonwoven fabric of the present disclosure, the heated gas and the cooling gas are merged by separately spraying the cooling gas that rapidly cools the resin or resin composition discharged from the spinneret, and the heated gas is cooled. Therefore, the fibrous resin or resin composition is cooled immediately after discharge, and the fusion of adjacent fibrous resin or resin compositions can be suppressed, and as a result, the variation in fiber diameter can be suppressed. Therefore, the above-mentioned fibrous nonwoven fabric with small variation in fiber diameter can be manufactured.

[0078] Hereinafter, preferred conditions for the method for producing a fibrous nonwoven fabric 2 of the present disclosure that differ from the method for producing a fibrous nonwoven fabric 1 of the present disclosure described above will be described.

[0079] In the method for producing a fibrous nonwoven fabric 2 of the present disclosure, from the viewpoint of suppressing an increase in fiber diameter, it is preferable that the discharge of the heated gas satisfies the above formula (1).

[0080] In the manufacturing method 2 of the fibrous nonwoven fabric of the present disclosure, when the temperature of the heated gas is Ta (°C) and the temperature of the molten resin or resin composition is Tp (°C), Tp-Ta (ΔT) is not particularly limited. For example, Tp-Ta (ΔT) may be approximately equal, or may be -30≦Tp-Ta≦30.

[0081] The temperature (Ta) of the heating gas may be selected depending on the type of aromatic polyether ketone. When the aromatic polyether ketone is polyether ether ketone, the temperature (Ta) of the heating gas is, for example, preferably 330°C to 550°C, more preferably 370°C to 520°C, and further preferably 430°C to 520°C. The temperature (Tp) of the molten resin or resin composition may be the same as the preferred range of Tp described in the above-mentioned method 1 for producing a fibrous nonwoven fabric.

[0082] The temperature of the cooling gas is preferably 30°C or less, more preferably 5°C to 25°C, and even more preferably 5°C to 20°C, from the viewpoint of effectively suppressing the variation in fiber diameter caused by the fusion of adjacent fibrous resins or resin compositions immediately after discharge.

[0083] Cooling gas flow rate: 1000Nm 3 / hour / m~20000Nm 3 / hr / m, preferably 3000Nm 3 / hour / m~18000Nm 3 / hr / m is more preferable, and 5000Nm 3 / hour / m~15000Nm 3 / hour / m is even more preferred.

[0084] The type of cooling gas is not particularly limited, and may be, for example, cooling air.

[0085] In the manufacturing method 2 of the fibrous nonwoven fabric of the present disclosure, the inventors have found that the aforementioned fibrous nonwoven fabric having smaller variation in fiber diameter can be manufactured by controlling Tp-Tq (ΔT') within a predetermined range, where Tp (°C) is the temperature of the molten resin or resin composition, and Tq (°C) is the temperature of the cooling gas. For example, it is preferable to discharge the heating gas and supply the cooling gas so as to satisfy the following formula (3). Formula (3) 350℃≦Tp-Tq≦550℃

[0086] The reason why the above-mentioned fibrous nonwoven fabric having a smaller variation in fiber diameter can be manufactured is not clear, but is presumed to be as follows. That is, when ΔT' is 350°C or more, the resin or resin composition discharged from the spinneret is moderately quenched and easily solidified. As a result, the resin or resin composition discharged in a fibrous form is less likely to fuse to each other, so that the variation in fiber diameter can be reduced. On the other hand, when ΔT' is 550°C or less, the resin or resin composition discharged from the spinneret is not cooled too rapidly, so that the stretching (pulling) effect by the heated gas is less likely to be impaired. As a result, insufficient stretching by the heated gas can be suppressed, and an increase in fiber diameter can also be suppressed.

[0087] Furthermore, from the viewpoint of producing the above-mentioned fibrous nonwoven fabric with small variation in fiber diameter, ΔT' is preferably 370°C to 520°C, and more preferably 400°C to 500°C.

[0088] The fibrous nonwoven fabric manufacturing apparatus used in the fibrous nonwoven fabric manufacturing method 2 of the present disclosure will be described with reference to FIG.

[0089] Fig. 2 is a schematic diagram showing an example of the configuration of a fibrous nonwoven fabric production apparatus 100. As shown in Fig. 2, the fibrous nonwoven fabric production apparatus 100 differs from the fibrous nonwoven fabric production apparatus 10 shown in Fig. 1 in that an attachment 34 for introducing cooling air is attached to the die 30.

[0090] The attachment 34 is detachable from the die 30. In the fibrous nonwoven fabric manufacturing apparatus 100, the die 30 ejects the molten resin or resin composition from the spinning nozzle 31 while injecting the heated gas (heated compressed gas) from the gas nozzle 32 to the vicinity of the opening of the spinning nozzle 31, and the attachment 34 supplies the cooling gas in the direction of the arrow B from the horizontal direction to the molten resin or resin composition and the heated gas ejected from the die 30. The resin or resin composition is stretched by the heated gas, and a fibrous material is obtained. At this time, the heated gas and the cooled gas are merged by separately blowing the cooling gas that rapidly cools the resin or resin composition ejected from the die 30, so that the fusion of the adjacent fibrous resin or resin composition immediately after ejection can be suppressed, and as a result, the variation in fiber diameter can be suppressed. According to the manufacturing method 2 of the fibrous nonwoven fabric of the present disclosure, a fibrous nonwoven fabric having an excellent Q value when used as a filter can be manufactured.

[0091] In addition, the attachment 34 is attached to the die 30 without any gaps in the vertical direction. Therefore, no air passage is formed through which external air is taken in, and the generation of vortexes above the attachment 34 is suppressed, making it difficult for turbulent heated gas to occur due to vortexes. Therefore, it is possible to suitably suppress adjacent fibrous resins or resin compositions from fusing due to turbulence immediately after discharge. In another embodiment, the attachment 34 may have a gap between it and the die 30 in the vertical direction. In this case, it is preferable that the attachment 34 and the die 30 are airtight in the machine direction from the viewpoint of suppressing the inflow of air in the machine direction and suppressing fusing due to turbulence.

[0092] The die 30 is heated in order to eject the heated gas, and there is a large temperature difference between the die 30 and the attachment 34. In order to suppress heat transfer between the attachment 34 and the die 30, it is preferable to interpose a heat insulating material between the lower surface of the die 30 and the upper surface of the attachment 34, for example.

[0093] The above-described fibrous nonwoven fabric of the present disclosure and the fibrous nonwoven fabric produced by the above-described production method 1 or production method 2 may be subjected to an electrostatic treatment.

[0094] The method of charging is not particularly limited as long as it can make the fibrous nonwoven fabric into an electret, and examples of the method include a corona charging method and a method in which water or an aqueous solution of a water-soluble organic solvent is applied to the fibrous nonwoven fabric and then dried to make it into an electret (for example, the methods described in JP-A-9-501604 and JP-A-2002-115177). In the case of the corona charging method, an electric field strength of 15 kV / cm or more is preferable, and an electric field strength of 20 kV / cm or more is more preferable.

[0095] [filter] The filter of the present disclosure includes the above-described fibrous nonwoven fabric of the present disclosure, which reduces variation in fiber diameter and provides excellent filtering precision. EXAMPLES

[0096] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.

[0097] [Example 1] A fibrous nonwoven fabric was produced using the manufacturing apparatus shown in Figure 1. Specifically, a twin-screw extruder was used to melt PEEK (polyether ether ketone, Solvey, KetaSpire KT-890P, resin viscosity at 400°C 99 Pa s), and the molten PEEK was fed to a die. The die was set at a temperature of 480°C (temperature Tp of molten PEEK), and heated air (temperature Ta: 350°C, flow rate: 300 Nm) was blown out from both sides of the spinning nozzle with a discharge rate of 0.2 g / min per spinning nozzle and a hole distance of 1.0 mm. 3 The diameter of the spinning nozzle of the die was 0.4 mm. The fibrous PEEK was then extruded at a rate of 15 g / m2. 2 The PEEK was collected on a collector so that the temperature was 176°C, and a fibrous nonwoven fabric was obtained. The crystallization temperature (Tc) and melting point (Tm) of PEEK were measured by the method described above. The crystallization temperature (Tc) of PEEK was 176°C, and the melting point (Tm) of PEEK was 347°C.

[0098] (Measurement of resin viscosity) The viscosity of the resin used in each Example and Comparative Example was determined as follows: Specifically, using a capillary rheometer (product name: Capillograph 1D PMD-C, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and the resin used in each Example and Comparative Example, the shear stress and shear strain rate were determined under the conditions below, and the shear viscosity (η) (Pa s) was calculated based on the following formula, which was used as the viscosity of the resin. [Measurement conditions] Measuring equipment: Capillograph 1D PMD-C (manufactured by Toyo Seiki Co., Ltd.) Capillary inner diameter: Φ=0.2[mm] Measurement temperature: 400℃ Capillary length / capillary inner diameter (L / D): 10 Piston speed: 2.5×10 2 (1 / sec) The shear viscosity (η) (Pa s) is calculated from the apparent shear stress and shear strain rate when the above L / D is 10 using the following formula:

[0099]

number

[0100] In the formula, τ (Pa) represents the apparent shear stress, and γ dot (Pa) (the symbol γ with a dot (·) on top; hereinafter, also referred to simply as “γ”) represents the shear strain rate. The apparent shear stress τ (Pa) is expressed as τ = pD / π4L using the piston load p (Pa), the capillary inner diameter D (mm), and the capillary length L (mm). The shear stress γ (Pa) is expressed as the volumetric flow rate Q (mm 3 / s) using γ=32Q / πD 3 It is expressed as:

[0101] [Examples 2 and 3] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that the temperature of the heated air was changed as shown in Table 1.

[0102] [Example 4] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that the PEEK used in Example 1 was changed to PEEK (polyether ether ketone, Solvey, KetaSpire KT-880P, resin viscosity at 400°C: 220 Pa s). The crystallization temperature (Tc) of PEEK was 177°C, and the melting point (Tm) of PEEK was 349°C.

[0103] [Example 5] A fibrous nonwoven fabric was produced using the production apparatus shown in Fig. 2. Specifically, the molten PEEK used in Example 1 was supplied to a die, and heated air (temperature Ta: 480°C, flow rate: 300 Nm) was blown out of both sides of the spinning nozzle at a discharge rate of 0.2 g / min per spinning nozzle from the die set temperature: 480°C (temperature Tp of molten PEEK). 3The diameter of the spinning nozzle of the die was 0.4 mm. Furthermore, the temperature Tq of the cooling air was 10° C., and the flow rate of the cooling air was 12000 Nm 3 The fiber PEEK was then applied at a weight of 15 g / m 2 The particles were collected on a collector so as to obtain a fibrous nonwoven fabric.

[0104] [Example 6] A fibrous nonwoven fabric was obtained in the same manner as in Example 5, except that the temperature of the molten PEEK, the temperature of the heating air, and the temperature of the cooling air were changed as shown in Table 1.

[0105] [Comparative Example 1] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that PEEK was melted using a single-screw extruder instead of the twin-screw extruder, and the die temperature and the heating air temperature were changed as shown in Table 2.

[0106] [Comparative Examples 2, 3, and 4] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that the temperature of the heated air was changed as shown in Table 2.

[0107] [Comparative Example 5] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that the PEEK used in Example 1 was changed to PP (polypropylene, ExxonMobil, Achieve 6936G2, weight average molecular weight: 55,000) and the die temperature and heating air temperature were changed as shown in Table 2.

[0108] [Comparative Example 6] A fibrous nonwoven fabric was obtained in the same manner as in Example 1, except that the PEEK used in Example 1 was changed to PET (polyethylene terephthalate, Mitsui Chemicals, Inc., Mitsui PET, IV: 0.62) and the die temperature and heating air temperature were changed as shown in Table 2.

[0109] The physical properties (average fiber diameter, CV value, basis weight, thickness, and air permeability) of the obtained fibrous nonwoven fabric were measured by the following methods.

[0110] (1) Average fiber diameter (μm) and coefficient of variation (CV value) of the fibers constituting the fibrous nonwoven fabric A photograph of the fibrous nonwoven fabric was taken at a magnification of 1000 times using an electron microscope (Hitachi S-3500N). The diameters of the fibers that could be measured were measured from the photograph obtained, and photographing and measurement were repeated until the total number of fibers measured exceeded 100. The arithmetic mean value of the obtained fiber diameters was taken as the average fiber diameter.

[0111] The standard deviation (Dp) of the measurement results was divided by the average fiber diameter (Da) to obtain the coefficient of variation (CV value) of the fiber diameter. CV value = [standard deviation (Dp) / average fiber diameter (Da)] x 100

[0112] (2) Weight (g / m 2 ) Three samples measuring 100 mm in the vertical direction and 100 mm in the horizontal direction were taken and the weight of each sample was measured. The average value obtained was converted to a value per unit area and rounded off to the nearest tenth to obtain the basis weight (g / m 2 ) was decided.

[0113] (3) Thickness The thickness of the sample, which had its basis weight measured, was measured at five points, namely the center and four corners, using a thickness gauge (PEACOCK, product number "R1-250", measuring probe 25 mmφ) under a load of 7 g / m 2 The thickness was measured by this method for 10 samples of which the basis weight was measured, and the average value was taken as the thickness (mm).

[0114] (4) Air permeability (cm 3 / cm 2 / sec) Five samples measuring 150 mm in the vertical direction × 150 mm in the horizontal direction were collected, and the air permeability was measured under flow conditions at a pressure difference of 125 Pa using a Frazier air permeability measuring device in accordance with JIS L 1096:2010.

[0115] (Measurement of fiber viscosity) The viscosity of the fibers constituting the fibrous nonwoven fabric obtained in each of the Examples and Comparative Examples was determined by the same method as described above (measurement of resin viscosity).

[0116] (Measurement of collection efficiency of non-heat-treated fiber nonwoven fabric) The dust collection efficiency of the non-heat-treated fibrous nonwoven fabric obtained in each of the Examples and Comparative Examples was measured by the following method. Three samples measuring 15 cm x 15 cm were taken from any part of the fibrous nonwoven fabric, and the collection efficiency of each sample was measured using a collection performance measuring device (Model 8130, manufactured by Tokyo Dylec Co., Ltd.). In measuring the collection efficiency, NaCl particle dust having a median diameter of 0.3 μm was generated by an atomizer, and then the sample was set in a holder, and the air volume was adjusted with a flow control valve so that the filter passing speed was 5.3 cm / sec, and the dust concentration was adjusted to 15 mg / m 3 ~20mg / m 3 The number of dust particles D2 upstream and D1 downstream of the sample were detected by a laser particle detector, and the collection efficiency was calculated by rounding off the value obtained by the following formula to one decimal place. The collection efficiency shown in Tables 1 and 2 is the arithmetic average value measured using three samples. Collection efficiency = [1-(D1 / D2)] (D1: number of dust particles downstream, D2: number of dust particles upstream)

[0117] (Measurement of pressure loss (Pa) of non-heat-treated fiber nonwoven fabric) The pressure drop of the non-heat-treated fibrous nonwoven fabric was determined by reading the static pressure difference between the upstream and downstream of the sample with a pressure gauge during the measurement of the collection efficiency. The pressure drops shown in Tables 1 and 2 are the arithmetic average values ​​determined using three samples.

[0118] (Conversion of collection efficiency of non-heat-treated fiber nonwoven fabric) The measured collection efficiency of the non-heat-treated fibrous nonwoven fabric, the measured average fiber diameter, the volume fraction of the fibrous nonwoven fabric, which is calculated by dividing the basis weight of the fibrous nonwoven fabric by the product of the density of PEEK multiplied by the thickness of the fibrous nonwoven fabric (basis weight / (density × thickness)), and the thickness of the fibrous nonwoven fabric are substituted into the above formula (b) to obtain E / e f Next, the volume fraction of the fibrous nonwoven fabric, the thickness of the fibrous nonwoven fabric, and the calculated E / e f Substituting into formula (b), and further, the average fiber diameter d f as 5×10 -6 The collection efficiency (5 μm equivalent value) was calculated by substituting the value of m (5 μm) into equation (b). The density of PEEK is 132kg / m 3 It is.

[0119] (Conversion of pressure loss of non-heat-treated fiber nonwoven fabric) The measured pressure loss of the non-heat-treated fibrous nonwoven fabric, the measured average fiber diameter, the volume fraction of the fibrous nonwoven fabric, and the thickness of the fibrous nonwoven fabric were substituted into formula (c) to calculate U0η. Next, the volume fraction of the fibrous nonwoven fabric, the thickness of the fibrous nonwoven fabric, and the calculated U0η were substituted into formula (c), and the average fiber diameter d f as 5×10 -6 The pressure loss (5 μm equivalent value) was calculated by substituting the value of m (5 μm) into formula (c).

[0120] (Calculation of Q value of non-heat-treated fiber nonwoven fabric) The Q value (5 μm equivalent value) was calculated from the obtained collection efficiency (5 μm equivalent value) and pressure loss (5 μm equivalent value) using formula (a).

[0121] (Measurement of collection efficiency of fibrous nonwoven fabric after heat treatment, etc.) The fibrous nonwoven fabric obtained in each Example and Comparative Example was exposed to high temperature conditions by the following method. Three samples of 15 cm x 15 cm were taken from any part of the fibrous nonwoven fabric, and each sample was fixed at the four corners with a 100 g weight and placed on a 1 mm thick aluminum plate heated to 250 ° C. After 24 hours, the aluminum plate was removed and left at room temperature for 6 hours to return to room temperature. Thereafter, the collection efficiency after heat treatment was measured by the same method as described above (measurement of collection efficiency of fibrous nonwoven fabric not heat treated). Furthermore, the various physical properties after heat treatment were measured, converted and calculated in the same manner as described above (Measurement of pressure drop (Pa) of non-heat-treated fibrous nonwoven fabric), (Conversion of collection efficiency of non-heat-treated fibrous nonwoven fabric), (Conversion of pressure drop of non-heat-treated fibrous nonwoven fabric) and (Calculation of Q value of non-heat-treated fibrous nonwoven fabric). The performance retention rate was calculated as the ratio of the Q value of the heat-treated fibrous nonwoven fabric to the Q value of the nonwoven fabric that was not heat-treated. A higher performance retention rate indicates that the decrease in the Q value due to heat treatment is more suppressed.

[0122] Tables 1 and 2 show the production conditions for the fibrous nonwoven fabrics of Examples 1 to 6 and Comparative Examples 1 to 6, and the evaluation results of the fibrous nonwoven fabrics.

[0123] [Table 1]

[0124] [Table 2]

[0125] The fibrous nonwoven fabrics obtained in Examples 1 to 6 had lower CV values ​​than the fibrous nonwoven fabrics obtained in Comparative Examples 1 to 4, and were shown to have superior Q values ​​of the fibrous nonwoven fabrics that were not heat-treated and the fibrous nonwoven fabrics after heat treatment. In the fibrous nonwoven fabric obtained in Comparative Example 5, the resin was dissolved during heating at 250° C., so the Q value of the fibrous nonwoven fabric after the heat treatment could not be measured. It was shown that the Q value of the fibrous nonwoven fabric obtained in Comparative Example 6 after the heat treatment was significantly lower than the Q value of the fibrous nonwoven fabric that was not heat treated.

[0126] The disclosure of Japanese Patent Application No. 2020-170104, filed on October 7, 2020, is incorporated herein by reference in its entirety. All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0127] 10, 100 Fiber nonwoven fabric manufacturing equipment 20 Extruder 21 Hopper 22 Compression section 30 Die (spinneret) 31 Spinning nozzle 32 Gas nozzle 34 Attachment 40 Collection mechanism 41 Perforated Belt 42 Laura 43 Air suction section 44 Blower 50 Gas Heating Equipment P Molten resin or resin composition G Heating gas

Claims

1. A fiber containing an aromatic polyether ketone, The fiber diameter variation coefficient of the fiber is 30% or more and 100% or less, The average fiber diameter of the fibers is 10 μm or less, Fibrous nonwovens, including meltblown nonwovens.

2. 2. The fibrous nonwoven fabric according to claim 1, wherein the viscosity of the fibers at 400° C. is 50 Pa·s to 500 Pa·s.

3. The fibrous nonwoven fabric according to claim 1 or 2, wherein the aromatic polyether ketone comprises polyether ether ketone.

4. A filter comprising the fibrous nonwoven fabric according to any one of claims 1 to 3.

5. The method includes a step of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or the resin composition by the heated gas to form a fibrous material, The flow rate of the heating gas is 150 Nm ３ / hour / m~1000Nm ３ / hour / m, A method for producing a fibrous nonwoven fabric, wherein the heated gas is discharged so as to satisfy the following formulas (1) and (2), where Ta (°C) is a temperature of the heated gas, Tp (°C) is a temperature of the molten resin or the resin composition, Tc (°C) is a crystallization temperature of the aromatic polyether ketone, and Tm (°C) is a melting point of the aromatic polyether ketone. Formula (1) Tc<Ta≦Tm+200 Formula (2) 40≦Tp-Ta≦190

6. The method for producing a fibrous nonwoven fabric according to claim 5, wherein the viscosity of the resin or the resin composition at 400° C. is 50 Pa·s to 500 Pa·s.

7. The method for producing a fibrous nonwoven fabric according to claim 5 or 6, wherein the heated gas is discharged so as to further satisfy the following formula (1)': Formula (1)' Tm-30≦Ta≦Tm+200

8. The flow rate of the heating gas is 250 Nm ３ / hour / m~850Nm ３ The method for producing a fibrous nonwoven fabric according to any one of claims 5 to 7, wherein the feed rate is 100 / hour / m.

9. A method for producing a fibrous nonwoven fabric, comprising the steps of discharging a molten resin or resin composition containing an aromatic polyether ketone from a spinneret together with a heated gas by a melt blowing method, and stretching the resin or resin composition with the heated gas while cooling the resin or resin composition with cooling gas supplied from both sides in the machine direction to form a fibrous material.

10. The flow rate of the cooling gas is 1000 Nm ３ / hour / m~20000Nm ３ 10. The method for producing a fibrous nonwoven fabric according to claim 9, wherein the flow rate is 1 / hour / m.

11. The method for producing a fibrous nonwoven fabric according to claim 9 or 10, wherein the temperature of the cooling gas is 30° C. or lower.

12. The method for producing a fibrous nonwoven fabric according to any one of claims 9 to 11, wherein, when a temperature of the molten resin or the resin composition is Tp (°C) and a temperature of the cooling gas is Tq (°C), the discharge of the heating gas and the supply of the cooling gas satisfy the following formula (3): Formula (3) 350℃≦Tp-Tq≦550℃

13. The method for producing a fibrous nonwoven fabric according to any one of claims 5 to 12, wherein the aromatic polyether ketone comprises polyether ether ketone.

14. The method for producing a fibrous nonwoven fabric according to any one of claims 9 to 13, wherein the resin or resin composition containing the aromatic polyether ketone is melted using a twin-screw extruder.

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