JP2020105459A - Composition for melt electrospinning, fiber, and method for producing the same - Google Patents

Abstract

To provide a composition for melt electrospinning, which can produce fibers that have highly hydrophobic fiber surfaces and have finer fiber diameters by a melt electrospinning method, with high production efficiency; a method for producing the fiber using the same; and the fiber.SOLUTION: The composition for melt electrospinning of the present invention includes a component (A): a polyolefin resin, a component (B): at least one of a sulfate ester salt and a sulfonate, and a component (C): a petroleum wax, wherein a content of the component (C) is 1 pt.mass or more and 20 pts.mass or less with respect to 100 pts.mass of the total components of the component (A), the component (B) and the component (C). The present invention also provides fibers that include the components (A) to (C) which are substantially the same as those in the composition, and of which a median of fiber diameters is 0.4 μm or larger and 3 μm or smaller. The present invention also provides a method for producing a fiber, which includes discharging a melt of the composition into an electric field and spinning the discharged melt by the electrospinning method.SELECTED DRAWING: Figure 1

Description

The present invention relates to a composition for melt electrospinning. The present invention also relates to a fiber and a method for manufacturing the fiber.

In recent years, various proposals have been made regarding an electrospinning method (hereinafter, also referred to as a melt electrospinning method) for producing a fiber having a small diameter by using a molten resin. Patent Document 1 discloses a method in which a polyolefin resin composition containing 0.01 to 1 part by weight of a hindered amine-based additive is melted by heating with respect to 100 parts by weight of the polyolefin resin, and spinning is performed by an electrospinning method. There is.

Further, the present applicant has previously proposed a method for producing a fiber by electrospinning using a mixture containing a resin having a melting point and an additive such as an alkyl sulfonate (see Patent Document 2). According to this manufacturing method, the raw material resin can be stably charged, and the small-diameter fiber can be electrospun.

JP, 2005-161051, A JP, 2017-190552, A

By the way, fine fibers are used in various fields, and it is desired to further reduce the diameter of the fibers and improve the surface properties of the fibers. In the melt electrospinning method, in order to efficiently produce a fiber having a smaller diameter and a desired surface physical property, an additive for expressing a desired surface physical property is used and a melt containing the additive is used. It is necessary to increase the chargeability and fluidity of the resin. The methods described in Patent Documents 1 and 2 are capable of producing a fine fiber, but further reducing the diameter of the produced fiber and exhibiting desired surface physical properties of the fiber, particularly hydrophobicity on the fiber surface. There was room for improvement regarding compatibility with manifestation.

Therefore, an object of the present invention is to provide a composition for melt electrospinning, which is capable of efficiently producing a fiber having a smaller diameter and having desired surface properties, a fiber, and a method for producing the same.

The present invention comprises the following components (A), (B) and (C):
A composition for melt electrospinning in which the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the following components (A), (B) and (C). Is provided.
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax.

The present invention also includes the following components (A), (B) and (C):
The content of the component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the components (A), (B) and (C).
The present invention provides a fiber having a median diameter of 0.4 μm or more and 3 μm or less.
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax.

The present invention also provides a method for producing a fiber, in which a molten liquid of the composition for molten electrospinning is discharged into an electric field and spun by an electrospinning method.

According to the present invention, by the melt electrospinning method, a fiber having a highly hydrophobic surface and a fiber having a smaller fiber diameter can be produced with high production efficiency.

FIG. 1 is a schematic diagram showing a fiber manufacturing method using a manufacturing apparatus.

The present invention will be described below based on its preferred embodiments. The composition for melt electrospinning of the present invention contains a polyolefin resin as component (A), at least one of a sulfate ester salt and a sulfonate as component (B), and petroleum wax as component (C), and It contains the component (C) in a predetermined ratio. Melt electrospinning is a method in which a molten liquid containing a resin, which is a raw material for fibers, is discharged into an electric field while a high voltage is applied. It is a method that can be formed.

The polyolefin resin as the component (A) has a fiber-forming property in the melt electrospinning and has a melting point. A resin having a melting point means a phase change from a solid to a liquid when the resin to be measured is heated in the differential scanning calorimetry (DSC method) before the resin is thermally decomposed. It is a resin showing an endothermic peak due to. The weight average molecular weight of the component (A) is preferably 10,000 or more, more preferably 40,000 or more, and preferably 150,000 or less, more preferably 100,000 or less. The weight average molecular weight is known, for example, by using the high temperature size exclusion chromatography (high temperature SEC) method or the high temperature gel permeation chromatography (high temperature GPC) method described in JP-A-2014-129614, and the weight average molecular weight is known. Polystyrene standard samples having different weight average molecular weights (for example, monodisperse polystyrene (model number: F450, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000, A500 and A300 manufactured by Tosoh Corporation. )) is subjected to the high temperature SEC method or the high temperature GPC method to prepare a molecular weight calibration curve in advance, and the molecular weight calibration curve can be measured by comparing the calibration curve with the result of the measurement sample.

Examples of the polyolefin resin include polyethylene resin, polypropylene resin, ethylene-α-olefin copolymer resin, ethylene-propylene copolymer and the like. These resins may be used alone or in combination of two or more. By using these resins, melt electrospinning can be efficiently performed.

At least one of the sulfate ester salt and the sulfonate salt which is the component (B) is used as a charging agent for modifying a generally hydrophobic polyolefin resin to express a high charge amount in an electric field. .. From the viewpoint of further improving the charge amount of the polyolefin resin and enhancing the spinnability, the component (B) preferably has a melting point not higher than the melting point of the polyolefin resin used in combination.

The sulfate ester salt used in the present invention is a kind of anionic surfactant. The sulfate ester salt refers to a salt of an organic compound having an alkyl group at the terminal in the molecular structure and a sulfate group at any position in the molecular structure. Such sulfates, for example, higher alcohol sulfuric acid ester salt _{(R-O-SO 3 M} ) alkyl sulfates such as polyoxyethylene alkyl ether sulfate _{(R-O- (CH 2 CH} 2 O) Alkyl ether sulfates such as _n- SO ₃ M) and the like. These can be used alone or in combination of two or more.

The sulfonate used in the present invention is also a kind of anionic surfactant. Sulfonate has either an alkyl group or an aromatic ring at the terminal in the molecular structure, or has an alkylene group in a part of the molecular structure, and has a sulfo group at any position in the molecular structure. It refers to the salt of the organic sulfonic acid that it has.

Examples of such a sulfonate include alkyl sulfonate (R-SO ₃ M), alkylbenzene sulfonate (R-Ph-SO ₃ M), alkylnaphthalene sulfonate (R-Np-SO ₃ M). ), olefin sulfonate _{(R-CH = CH- (CH} 2) n -SO 3 M and _{R-CH (-OH) (CH} 2) n -SO 3 M), alkyl sulfosuccinates (R-OOC _{-CH 2 -CH (-SO 3 M)} -COOM), dialkyl sulfosuccinates _{(R-OOC-CH 2 -CH} (-SO 3 M) -COO-R), α- sulfofatty acid ester salt (R- _{CH (-SO 3 M) -COO-} CH 3), acyl isethionates _{(R-CO-O- (CH} 2 CH 2) -SO 3 M), acyl taurine salt _{(R-CO-NH- (CH} 2) _2- SO ₃ M), acylalkyl taurine salt (R—CO—N(—R′)-(CH ₂ ) ₂ —SO ₃ M), and other N-alkyl-N-acylaminoalkyl sulfonates, β- naphthalene sulfonate-formalin condensate _{(M-O 3 S-Np-} (CH 2 -Np (-SO 3 M)) n -H) can be mentioned. These can be used alone or in combination of two or more.

In the above-mentioned sulfuric acid ester salt and sulfonate, R represents a linear or branched alkyl group, and the carbon number thereof is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, preferably Is 22 or less, more preferably 20 or less, and further preferably 18 or less. R'represents a linear or branched alkyl group, and the carbon number thereof is preferably 5 or less. Ph represents an optionally substituted phenyl group. Np represents an optionally substituted naphthyl group. M represents a monovalent cation, preferably a metal ion, and more preferably a sodium ion. n is preferably 6 or more, more preferably 8 or more, still more preferably 10 or more, preferably 24 or less, more preferably 22 or less, still more preferably 20 or less. One of these sulfate ester salts and sulfonates may be used alone, or a mixture of two or more thereof may be used.

Of these sulfates and sulfonates, alkyl sulfates, alkyl ether sulfates, alkyl sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, olefin sulfonates, and N-alkyl-N-acyl It is preferable to use at least one of aminoalkyl sulfonates, and it is more preferable to use N-alkyl-N-acylaminoalkyl sulfonates. By using such a component as the component (B), it is possible to more efficiently perform melt electrospinning on a fiber having a small fiber diameter.

The petroleum wax, which is the component (C), can enhance the fluidity of the molten composition when the composition for molten electrospinning of the present invention is melted and subjected to electrospinning, and can produce fibers having a smaller diameter. In addition, it is used to develop hydrophobicity on the surface of the produced fiber. The component (C) has a weight average molecular weight smaller than that of the component (A), and specifically, preferably 100 or more, more preferably 200 or more, still more preferably 250 or more, still more preferably 300 or more. Further, it is preferably 1000 or less, more preferably less than 1000, still more preferably 900 or less, still more preferably 800 or less. The weight average molecular weight can be measured by, for example, a gas chromatography mass spectrometry (GC-MS) method (GC-MS device, manufactured by JEOL Ltd., model number: JMS-T100GC). Hydrophobicity expressed in the fiber means that the dispersibility of the fiber in water or an aqueous liquid is reduced, and that the water or the aqueous liquid is not retained between the fibers, or the retention is low, and Includes meaning. The hydrophobicity can be evaluated, for example, by using the contact angle or the liquid repellency of the aqueous liquid as an index, as described in detail in Examples below.

The petroleum wax used in the present invention is a hydrocarbon that is present in petroleum and is solid at room temperature, and is preferably composed of one or more straight-chain or branched-chain or cyclic or acyclic aliphatic saturated hydrocarbons. It Examples of petroleum waxes include paraffin waxes mainly containing straight-chain aliphatic saturated hydrocarbons, and microcrystalline waxes containing straight-chain, branched-chain and cyclic aliphatic saturated hydrocarbons. These waxes can be used alone or in combination of two or more.

Of these petroleum waxes, at least one of paraffin wax and microcrystalline wax is preferably used, paraffin wax or microcrystalline wax is preferably used, and paraffin wax is more preferably used. By using such a component as the component (C), when the composition for melt electrospinning is used for melt electrospinning, the fluidity of the melt of the composition can be increased and discharge and stretching can be efficiently performed. In addition to this, hydrophobicity can be developed on the surface of the spun fiber. As a result, it is possible to manufacture fibers having a smaller fiber diameter and exhibiting hydrophobicity with high production efficiency.

From the viewpoint of stably performing melt electrospinning, the content of the component (A) contained in the composition for melt electrospinning is 100 parts by mass of the total amount of the components (A), (B) and (C). On the other hand, it is preferably 70 parts by mass or more, more preferably 75 parts by mass or more, further preferably 80 parts by mass or more, and preferably 99.5 parts by mass or less, It is more preferably 97 parts by mass or less, and further preferably 90 parts by mass or less.

From the same viewpoint, the content of the component (B) contained in the composition for melt electrospinning is 0.5 with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). It is preferably at least 1 part by mass, more preferably at least 1 part by mass, even more preferably at least 4 parts by mass, preferably at most 10 parts by mass, and at most 8 parts by mass. Is more preferable, and 6 parts by mass or less is further preferable.

Included in the composition for melt electrospinning from the viewpoint of increasing the fluidity of the melted composition to enable the production of finer fibers and effectively expressing the hydrophobicity of the surface of the produced fiber. The content of the component (C) is preferably 1 part by mass or more, and preferably 5 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B) and (C). Is more preferable, 7 parts by mass or more is more preferable, 20 parts by mass or less is preferable, 17 parts by mass or less is more preferable, and 15 parts by mass or less is further preferable.

Further, from the viewpoint of further improving the fluidity of the melted composition to further reduce the diameter of the fiber and further improve the production amount of the fiber, the melting point or dropping point of the component (C) is It is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 65°C or higher, and preferably 120°C or lower, more preferably 100°C or lower, It is more preferably 90°C or lower. The melting point or the dropping point can be measured according to JIS K 0064 or JIS K 2220 using, for example, a melting point/dropping point measuring device (manufactured by METTLER TOLEDO, model number: DP90 automatic dropping point/softening point measuring system). it can.

The composition for melt electrospinning of the present invention contains an additive as a component (D) in addition to the components (A), (B) and (C) described above, as long as the effect of the present invention is not impaired. It can also be used. Examples of the additive that is the component (D) include an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a metal deactivator. Examples of the antioxidant include a phenol-based antioxidant, a phosphite-based antioxidant, and a thio-based antioxidant. Examples of the light stabilizer and the ultraviolet absorber include hindered amines, nickel complex compounds, benzotriazoles and benzophenones. Examples of the lubricant include higher fatty acid amides such as stearic acid amide. Examples of the antistatic agent include fatty acid partial esters such as glycerin fatty acid monoester. Examples of the metal deactivator include phosphones, epoxies, triazoles, hydrazides, oxamides and the like. These additives may be used alone or in combination of two or more. When the composition for melt electrospinning further contains the component (D), the content of the component (D) contained in the composition is such that the component (A), the component (B), the component (C) and the component (D). Is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and further preferably 10 parts by mass or less, and 1 part by mass. The following is more preferable. In this case, the content of each of the component (A), the component (B) and the component (C) is based on 100 parts by mass of the total amount of the component (A), the component (B), the component (C) and the component (D). Should be in the above range.

The method for producing the composition for melt electrospinning is not particularly limited, and, for example, the component (B) and the component (C) are added to the component (A) which is heated and melted, and the component (D) is added if necessary. Can be further added, and these can be kneaded to produce. Such a composition for melt electrospinning may be produced as a masterbatch by adding the component (B) and the component (C) to the previously melted component (A) and kneading them. Alternatively, the component (A), the component (B) and the component (C) may be individually supplied to a manufacturing apparatus described below, and kneading may be performed while heating and melting in the apparatus. When the composition for melt electrospinning is produced as a masterbatch, it can be cooled, molded into pellets or the like, and stored as a solid.

According to the composition for melt electrospinning having the above constitution, by containing the component (A) and the component (B), the molten composition is suitable for electrospinning without impairing the properties of the composition. By imparting a charge amount, it is possible to achieve both improvement in fiber production efficiency and reduction in the diameter of spun fiber. Further, by containing the component (C) in a predetermined ratio in the composition, the viscosity of the melted composition may be reduced to improve the fluidity, and the fiber to be spun may have a smaller diameter. it can. Furthermore, since the component (C) has a lower molecular weight than the component (A), the component (C) is likely to be distributed on the surface of the fiber after the composition is spun, so that the component (C) is spun from the composition. The hydrophobicity of the fiber is high. As a result, it is possible to manufacture a fiber having a smaller diameter and exhibiting high hydrophobicity on the surface, while improving the manufacturing efficiency of the fiber. In particular, according to a preferred embodiment of the composition for melt electrospinning, it has a high level of improving the production efficiency of the fiber, reducing the diameter of the fiber to be spun, and expressing the high hydrophobicity of the spun fiber. It becomes a thing.

While the above is the description of the composition for melt electrospinning, a method for producing fibers using the composition for melt electrospinning will be described below. This method comprises spinning a composition for melt electrospinning containing the above-mentioned component (A), component (B) and component (C) and containing the component (C) in a predetermined ratio by a melt electrospinning method. is there.

The fiber manufacturing method of the present invention can be suitably carried out by the manufacturing apparatus 10 shown in FIG. The manufacturing apparatus 10 shown in FIG. 1 is roughly divided into a molten composition supply unit 10A, an electrode unit 10B, a fluid ejection unit 10C, and a collection unit 10D.

The manufacturing apparatus 10 includes a molten composition supply unit 10A. The molten composition supply unit 10A includes a housing 11 that includes a discharge nozzle 12 that discharges a molten liquid of the above-described molten electrospinning composition and a hopper 19 that supplies the molten electrospinning composition 1P.

In the casing 11, the molten electrospinning composition 1P supplied from the hopper 19 can be heated and melted in the casing 11 to form a molten liquid R of the molten electrospinning composition. The melt R can be supplied toward the discharge nozzle 12 described later by a screw (not shown) provided in the housing 11.

The discharge nozzle 12 is a member that discharges the molten liquid R of the composition for molten electrospinning into an electric field, and includes a nozzle base 13 and a discharge nozzle tip portion 14. The discharge nozzle 12 is made of a conductive material such as metal. The nozzle base 13 and the discharge nozzle tip portion 14 are electrically insulated by an insulating member (not shown). Therefore, even if a high voltage is applied to the tip portion 14 of the discharge nozzle, the voltage is prevented from being directly applied to the housing 11. The casing 11, the discharge nozzle 12, and the nozzle base 13 are in communication with each other, and the molten liquid R in the casing 11 can be discharged from the discharge port of the discharge nozzle tip portion 14. The discharge nozzle tip portion 14 is grounded and grounded.

The discharge nozzle tip portion 14 is heated by, for example, heat transfer from a heater (not shown) provided in the nozzle base 13 or heat transfer from the melt R in the housing 11. The heating temperature of the melt R at the discharge nozzle tip portion 14 depends on the constituent components of the composition for melt electrospinning, but is preferably 100° C. or higher, more preferably 200° C. or higher, and preferably 450° C. or lower, It is preferably 400° C. or lower.

The manufacturing apparatus 10 further includes an electrode unit 10B. The electrode unit 10B includes a charging electrode 21 arranged at a position facing the ejection nozzle 12 with a space therebetween, and a high voltage generator 22 connected to the charging electrode 21.

The charging electrode 21 is disposed at a position spaced apart from the discharge nozzle tip portion 14 by a predetermined distance, facing the discharge nozzle tip portion 14 and spaced apart. With this configuration, an electric field is generated between the tip portion 14 of the discharge nozzle 12 and the charging electrode 21 to which the high voltage is applied by the high voltage generator 22, and the molten liquid discharged from the discharge nozzle tip portion 14 is generated. R can be charged. The charging electrode 21 is preferably made of a conductive material such as metal or covered with a dielectric.

The distance between the discharge nozzle 12 and the charging electrode 21 depends on the fiber diameter (diameter) of the desired fiber and the collecting property on the collecting electrode 27 described later, but is preferably 10 mm or more, more preferably 30 mm or more, preferably It is 150 mm or less, more preferably 75 mm or less. If the distance between the discharge nozzle 12 and the charging electrode 21 is within this range, the melt R can be sufficiently charged in the electric field, and in addition to the spark or corona discharge between the discharge nozzle 12 and the charging electrode 21. Is less likely to occur, and malfunction of the manufacturing apparatus 10 is less likely to occur.

The manufacturing apparatus 10 further includes a fluid ejection unit 10C. The fluid ejecting unit 10C includes the fluid ejecting device 23 below the virtual straight line connecting the molten composition supply unit 10A and the electrode unit 10B. The fluid ejection device 23 is provided between the molten composition supply unit 10A and the electrode unit 10B.

An air flow A flows between the tip of the discharge nozzle tip 14 and the charging electrode 21 in a direction intersecting the direction connecting the two. The air flow A is ejected from the fluid ejecting device 23. The molten liquid R discharged from the discharge nozzle tip portion 14 is transported to the air flow A, so that it is possible to form finer fibers. For this purpose, it is preferable to use air as the heating fluid as the air flow A. The temperature of the heated air depends on the constituent components of the composition for melt electrospinning, but is preferably 100° C. or higher, more preferably 200° C. or higher, and preferably 500° C. or lower, more preferably 400° C. It is as follows. For the same purpose, the flow rate of the air flow A at the discharge port of the fluid ejection device 23 when ejecting the air flow A is preferably 50 L/min or more, more preferably 150 L/min or more, and preferably Is 500 L/min or less, more preferably 400 L/min or less.

The manufacturing apparatus 10 further includes a collection unit 10D. The collection unit 10D includes a collection sheet 24, a conveyor 25, a high voltage generator 26, and a collection electrode 27. The collection unit 10D is provided at a position above a virtual straight line connecting the molten composition supply unit 10A and the electrode unit 10B and at a position facing the fluid ejection unit 10C. Each of the collection units 10D is electrically connected.

The collecting sheet 24 collects the fibers F formed by being conveyed by the airflow A and being stretched. The collection sheet 24 may be in the form of a long strip, for example. The collecting sheet 24 is unrolled from the original roll 24 a and conveyed to the conveyer conveyor 25. The collection sheet 24 can be made of resin such as polypropylene.

The conveyor 25 conveys the fused electrospun fibers to the downstream manufacturing process. A collection electrode 27 for collecting the melt-electrospun fibers is arranged inside the transport conveyor 25. A high voltage generator 26 is connected to the collection electrode 27, and a high voltage is applied to the collection electrode 27 by the high voltage generator 26. By applying a high voltage to the collecting electrode 27, the fibers F are attracted to the side of the conveyor 25 that is negatively charged and are deposited on the surface of the collecting sheet 24. Further, the collection electrode 27 may be grounded instead of the high voltage generator 26.

While the above is the description of the manufacturing apparatus 10 shown in FIG. 1, the fiber manufacturing method of the present invention using the manufacturing apparatus 10 will be described below.

First, the hopper 19 is filled with the molten electrospinning composition 1P, and the molten electrospinning composition is heated and melted in the housing 11. The melt R is extruded toward the discharge nozzle 12 by the rotation of the screw, and the melt R is supplied to the discharge port of the discharge nozzle tip portion 14.

Next, the melt R is discharged into the electric field from the discharge nozzle tip portion 14 and is spun by the electrospinning method. The electric field can be generated by, for example, grounding the tip portion 14 of the discharge nozzle 12 and connecting the charging electrode 21 to the high voltage generator 22 to apply a voltage. The charged melted liquid R is stretched by the self-repulsive force generated in the melted liquid R itself and is attracted toward the charging electrode 21 by the electric attraction. At that time, the melt R is repeatedly drawn by the attractive force and the self-repulsive force to form ultrafine fibers.

From the viewpoint of facilitating the stretching of the melt R during electrospinning and making the fiber to be produced finer, the viscosity of the melt of the composition for melt electrospinning is 200° C. and a shear rate of 10 s ⁻¹ . Under the conditions, it is preferably 1 Pa·s or more, more preferably 4 Pa·s or more, further preferably 10 Pa·s or less, and further preferably 8 Pa·s or less. The viscosity of the melt can be measured using, for example, a rotary rheometer (MCR302 manufactured by Anton Paar).

From the same viewpoint, it is preferable to set the melt flow rate (MFR) of the melted composition for molten electrospinning to 10 g/min or more, particularly 100 g/min or more at the discharge port of the discharge nozzle tip portion 14. The melt flow rate (MFR) is in accordance with JIS K 7210. For example, when a polypropylene resin is used as the component (A), a die having a hole diameter of 2.095 mm and a length of 8 mm is used at 230° C. under a load of 2.16 kg. Is measured.

The discharge rate of the molten composition for molten electrospinning is preferably 1 g/min or more, and more preferably 2 g/min or more, from the viewpoint of achieving both the efficiency of stretching the melt R and the production efficiency of the fiber. More preferably, it is preferably 20 g/min or less, more preferably 5 g/min or less.

After that, by further blowing the airflow A from the fluid ejecting device 23 toward the molten liquid R, the molten liquid R discharged from the discharge nozzle tip portion 14 is further stretched and conveyed while generating ultrafine fibers. It The molten liquid R discharged from the discharge nozzle tip portion 14 is conveyed to the airflow A before reaching the charging electrode 21, so that the flight direction of the molten liquid R is changed and the molten liquid R is stretched and extra-fine. The fibers F are produced by being solidified and solidified. The fibers F generated from the molten liquid R are conveyed by the air flow A and are attracted by the electric attraction generated in the collection electrode 27, and are deposited on the surface of the collection sheet 24 facing the fluid ejecting apparatus 23. ..

The applied voltage applied between the discharge nozzle 12 and the charging electrode 21 or the collecting electrode 27 is preferably −100 kV or higher, more preferably −80 kV or higher, and preferably −5 kV or lower, more preferably −10 kV. It is as follows. When the applied voltage is within this range, the melt R is likely to be favorably charged, and the production efficiency of fibers having a small fiber diameter can be further enhanced. In addition, sparks or corona discharge are less likely to occur between the discharge nozzle 12 and the charging electrode 21 or the collecting electrode 27, and malfunction of the device is less likely to occur.

The molten liquid R discharged from the discharge nozzle 12 in the present manufacturing method has a high electric charge due to being discharged into the electric field. The charge amount of the melt R is preferably as high as possible from the viewpoint of making the fibers ultrafine by electrospinning, specifically, it is preferably 2000 nC/g or more, more preferably 3000 nC/g or more. It is more preferably 5000 nC/g or more, further preferably 9000 nC/g or more. Such charge amount uses the above-mentioned component (B) in the composition for melt electrospinning, and makes each content of the component (A), the component (B) and the component (C) within the above-mentioned range. This can be easily achieved. The amount of charge on the melt R is, for example, 1 minute of the charge of the melt R charged in a metal container placed in a Faraday cage (KQ1400, manufactured by Kasuga Electric Co., Ltd.), and a coulomb meter (Kasuga) connected to the Faraday cage. It can be measured by using Denki Co., Ltd., NK-1002A). The measurement conditions can be 27° C., 50% RH, applied voltage: 20 kV, discharge rate of melt R: 2 g/min, heating temperature of melt R: 190° C., temperature of air flow A: 340° C. ..

The fiber manufactured in this manner is considered to be one continuous fiber between the discharge nozzle 12 and the collection sheet 24. Even if the fibers are temporarily cut due to the manufacturing conditions and the surrounding environment, the cut fibers immediately come into contact with each other. As a result, the ultrafine fibers are discharged from the discharge nozzle 12 to the collecting sheet 24. In between, it is considered as if it were one continuous fiber.

The fiber produced through the above steps is spun using the composition for melt electrospinning containing the above-mentioned component (A), component (B) and component (C) as a raw material, and is produced by melt electrospinning. Since there is substantially no alteration of the composition, the composition of the melt electrospinning composition as the raw material and the composition of the fiber as the product are substantially the same. That is, the fiber of the present invention contains the above-mentioned component (A), component (B) and component (C), and with respect to 100 parts by mass of the total component of component (A), component (B) and component (C). Thus, the content of the component (C) is preferably 1 part by mass or more and 20 parts by mass or less. Moreover, the description regarding the composition for melt electrospinning described above is appropriately applied to the description regarding the component (A), the component (B), the component (C) and the component (D) in the fiber of the present invention.

According to the present invention, a fiber having a desired fiber diameter and fiber length can be produced according to the conditions for carrying out the melt electrospinning method. In particular, it is possible to manufacture fibers called nanofibers having a very small fiber diameter. The fiber diameter of the fiber of the present invention is preferably 0.4 μm or more, more preferably 3 μm or less, and further preferably 1 μm or less when the fiber diameter is represented by a circle equivalent diameter. .. Further, the fiber length of the fiber of the present invention is, as a median fiber length, preferably 10 mm or more, more preferably 50 mm or more, and further preferably 100 mm or more.

The fiber diameter and the fiber length of the fused electrospun fiber are, for example, fibers obtained by removing defects such as a mass of the fused electrospun fiber, intersections of the fused electrospun fiber, and polymer droplets from a two-dimensional image obtained by observation with a scanning electron microscope (SEM). It is possible to measure by directly selecting 500 of the above, the length when a line orthogonal to the longitudinal direction of the fiber is drawn is the fiber diameter, and the length in the longitudinal direction of the fiber is directly read as the fiber length. The median fiber diameter can be obtained from the measured fiber diameter distribution, and the median fiber length can be obtained from the measured fiber length distribution.

From the viewpoint of more effectively exhibiting hydrophobicity on the fiber surface, the fiber of the present invention is preferably subjected to heat treatment. The method of heat treatment of the fiber is not particularly limited, for example, a method of treating the fiber by blowing hot air, a method of irradiating the fiber with infrared rays, a method of immersing the fiber in a heating liquid such as hot water, a pair of heated rolls Examples thereof include a method of passing the fibers between them, a method of holding the fibers in a heated space such as a constant temperature bath, and a method of pressing the fibers by sandwiching them with a heated metal plate. These methods may be carried out on the spun fibers as they are, may be carried out at the same time as forming the fibers into a predetermined shape to give a molded product of the fibers, or may be carried out after forming the molded product. Good. By performing such a treatment on the fiber, the component (C) is easily distributed on the fiber surface, and thus the hydrophobicity of the fiber can be further enhanced.

When the heat treatment is performed, it is preferable to heat the fiber at a temperature equal to or lower than the melting point of the component (A), from the viewpoint of making the fiber more hydrophobic and increasing the rigidity of the fiber. Specifically, when the melting point of the component (A) is MP (°C), it is preferably (MP-100)°C or higher, more preferably (MP-80)°C or higher, even more preferably (MP-60)°C. As described above, the temperature is more preferably (MP-40)°C or higher, and preferably (MP-10)°C or lower. From the same viewpoint, when the heating method in the heating step is a method of holding in a heated space such as a constant temperature bath, the heating time is preferably 5 minutes or more, and preferably 30 minutes or less, and further preferably Is less than 20 minutes.

When polypropylene (melting point: about 150° C.) is contained as the component (A), for example, as a thermoplastic resin, the heating temperature is preferably 50° C. or higher, more preferably 70° C. or higher, further preferably 90° C. or higher, and , Preferably 140° C. or lower. From the same viewpoint, when the heating method in the heating step is a method of holding in a heated space such as a constant temperature bath, the heating time is preferably 5 minutes or more, and preferably 30 minutes or less, It is preferably 20 minutes or less.

The fiber obtained by the present invention is highly hydrophobic and has a fine fiber diameter. The fiber of the present invention can be used for various purposes as it is or as a molded product of fibers in which fibers are accumulated. Examples of the shape of the molded body include a sheet-shaped body, a cotton-shaped body, and a thread-shaped body. The fiber molded body may be used by laminating it with another sheet or by containing various liquids, fine particles, fibers and the like. The sheet-shaped body of fibers spun by the melt electrospinning method can be used as a fiber product such as a woven fabric or a non-woven fabric as a long fiber or a short fiber. It is suitably used as a sheet that is attached to the skin, teeth, gums, hair, non-human mammal skin, teeth, gums, plant surfaces such as branches and leaves. Further, it is also suitably used as a high-performance filter having a high dust collecting property and a low pressure loss, a battery separator that can be used at a high current density, a cell culture substrate having a high pore structure, and the like. A cotton-like body of fused electrospun fibers is preferably used as a soundproofing material, a heat insulating material, or the like. In addition to the above-mentioned applications, it can also be used as an electromagnetic wave shielding material, a bioartificial device, an IC chip, an organic EL, a solar cell, an electrochromic display element, a photoelectric conversion element and the like.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments. For example, in the manufacturing apparatus 10 shown in FIG. 1, the molten composition supply unit 10A and the fluid ejection unit 10C were separately provided, but instead of this, the fluid composition injection unit 10C is incorporated in the molten composition supply unit 10A. Good. Specifically, as disclosed in JP-A-2016-204816, a nozzle for discharging a melt of a composition for molten electrospinning, an electrode for generating an electric field between the nozzle, and a voltage applied to the electrode. Which comprises a high voltage generating device and a collecting part for collecting fibers produced from the composition for molten electrospinning, and a flow passage through which a molten liquid can flow is formed between the casing and the nozzle. The manufacturing apparatus may have a fluid ejection unit formed so as to surround the flow passage. In this case, instead of the electrode section 10B, a voltage is applied to the collection electrode 27 in the collection section 10D to generate an electric field between the collection electrode 27 and the nozzle, and in this state, the discharge nozzle 12 directs the collection section 10D. Alternatively, the melt may be directly discharged. The fluid ejecting unit 10C in the present embodiment is capable of ejecting the air flow A along the ejection direction of the molten liquid R from the ejection nozzle 12.

Further, in the manufacturing apparatus 10 shown in FIG. 1, the electrode for generating the electric field with the discharge nozzle 12 was provided as the charging electrode 21 separately from the molten composition supply unit 10A. The charging electrode 21 may be incorporated in the composition supply unit 10A. Specifically, as shown in JP-A-2016-204816, the charging electrode 21 is a concave curved surface electrode in which a concave curved surface is arranged so as to surround the ejection nozzle 12, and a voltage can be applied to the electrode. It may be. In this case, the collection unit 10D arranged facing the discharge nozzle 12 is provided with a suction means such as a suction box which is not electrically connected, instead of the collection electrode 27, and the spun fiber F is spun. May be suctioned so that the fibers can be deposited on the collection sheet 24.

With respect to the embodiments described above, the present invention further discloses the following composition for melt electrospinning, and fibers and a method for producing the fibers.
<1>
Including the following components (A), (B) and (C):
A composition for melt electrospinning in which the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the following components (A), (B) and (C). ..
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax.

<2>
The component (B) is an alkyl sulfate, an alkyl ether sulfate, an alkyl sulfonate, an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, an olefin sulfonate, and an N-alkyl-N-acylaminoalkyl sulfonate. The composition for melt electrospinning according to <1> above, which is at least one of the above.
<3>
The composition for melt electrospinning according to <1> or <2>, wherein the component (C) is a paraffin wax or a microcrystalline wax.
<4>
The composition for melt electrospinning according to any one of <1> to <3>, wherein the melting point or dropping point of the component (C) is 50° C. or higher and 120° C. or lower.

<5>
The component (C) has a weight average molecular weight smaller than that of the component (A), and is preferably 100 or more, more preferably 200 or more, still more preferably 250 or more, still more preferably 300 or more, and preferably Is 1000 or less, more preferably less than 1000, still more preferably 900 or less, and even more preferably 800 or less. The composition for melt electrospinning according to any one of the above items <1> to <4>.
<6>
The composition for melt electrospinning according to any one of <1> to <5>, wherein the component (C) is more preferably paraffin wax.
<7>
The content of the component (A) is preferably 70 parts by mass or more, and 75 parts by mass with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). More preferably, it is more preferably 80 parts by mass or more, further preferably 99.5 parts by mass or less, more preferably 97 parts by mass or less, and 90 parts by mass or less. More preferably, the composition for melt electrospinning according to any one of the above items <1> to <6>.

<8>
The content of the component (B) is preferably 0.5 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B) and (C). It is more preferably at least 4 parts by mass, more preferably at least 4 parts by mass, preferably at most 10 parts by mass, more preferably at most 8 parts by mass, and at most 6 parts by mass. More preferably, the composition for melt electrospinning according to any one of the above items <1> to <7>.
<9>
The content of the component (C) is preferably 1 part by mass or more, and preferably 5 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B) and (C). Is more preferable, 7 parts by mass or more is more preferable, 20 parts by mass or less is preferable, 17 parts by mass or less is more preferable, 15 parts by mass or less is further preferable, and The composition for melt electrospinning according to any one of <1> to <8>.
<10>
As component (D), at least one of an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent and a metal deactivator is contained,
The content of the component (D) is 0.01 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B), (C) and (D). It is preferable that the amount is 0.05 parts by mass or more, more preferably 10 parts by mass or less, and further preferably 1 part by mass or less, in the above <1> to <9>. The composition for melt electrospinning according to any one of claims.

<11>
A method for producing a fiber, wherein a melt of the composition for molten electrospinning according to any one of the above items <1> to <10> is discharged into an electric field and spun by an electrospinning method.
<12>
The discharge nozzle that discharges the molten liquid is grounded, and the charging electrode that is arranged apart from the discharge nozzle is connected to a high voltage generator to generate the electric field between the discharge nozzle and the charging electrode. The method for producing the fiber according to <11>.
<13>
Separately from the discharge nozzle and the charging electrode, a collecting part for collecting fibers generated from the composition for molten electrospinning is used, and the collecting part is electrically connected to the collecting part. The method for producing a fiber according to <11> or <12>, wherein the fiber is collected in
<14>
The method for producing a fiber according to any one of <11> to <13>, in which a heating fluid is sprayed toward the melt discharged from the discharge nozzle to convey the fiber generated from the melt.

<15>
Including the following components (A), (B) and (C):
The content of the component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the components (A), (B) and (C).
A fiber having a median diameter of 0.4 μm or more and 3 μm or less.
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax.
<16>
The component (B) is an alkyl sulfate, an alkyl ether sulfate, an alkyl sulfonate, an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, an olefin sulfonate, and an N-alkyl-N-acylaminoalkyl sulfonate. The fiber according to <15>, which is at least one of the following.
<17>
The fiber according to <15> or <16>, wherein the component (C) is a paraffin wax or a microcrystalline wax.

<18>
The fiber according to any one of <15> to <17>, wherein the melting point or dropping point of the component (C) is 50° C. or higher and 120° C. or lower.
<19>
The component (C) has a weight average molecular weight smaller than that of the component (A), and is preferably 100 or more, more preferably 200 or more, still more preferably 250 or more, still more preferably 300 or more, and preferably Is 1000 or less, more preferably less than 1000, still more preferably 900 or less, and even more preferably 800 or less, according to any one of the above <15> to <18>.
<20>
The fiber according to any one of <15> to <19>, wherein the component (C) is more preferably paraffin wax.
<21>
The content of the component (A) is preferably 70 parts by mass or more, and 75 parts by mass with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). More preferably, it is more preferably 80 parts by mass or more, further preferably 99.5 parts by mass or less, more preferably 97 parts by mass or less, and 90 parts by mass or less. More preferably, the fiber according to any one of <15> to <20>.

<22>
The content of the component (B) is preferably 0.5 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B) and (C). It is more preferably at least 4 parts by mass, more preferably at least 4 parts by mass, preferably at most 10 parts by mass, more preferably at most 8 parts by mass, and at most 6 parts by mass. More preferably, the fiber according to any one of <15> to <21>.
<23>
The content of the component (C) is preferably 1 part by mass or more, and preferably 5 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B) and (C). Is more preferable, 7 parts by mass or more is more preferable, 20 parts by mass or less is preferable, 17 parts by mass or less is more preferable, 15 parts by mass or less is further preferable, and The fiber according to any one of <15> to <22>.
<24>
As component (D), at least one of an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent and a metal deactivator is contained,
The content of the component (D) is 0.01 parts by mass or more based on 100 parts by mass of the total amount of the components (A), (B), (C) and (D). It is preferable that the amount is at least 0.05 part by mass, more preferably at least 0.05 part by mass, preferably at most 10 parts by mass, more preferably at most 1 part by mass. The fiber according to any one.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the invention is not limited to such embodiments.

[Example 1]
Using the manufacturing apparatus 10 shown in FIG. 1, a polypropylene resin (manufactured by PolyMirae, MF650Y, weight average molecular weight 79000) as the component (A) and an acylalkyl taurine salt (N-stearoyl-N-methyltaurine) as the component (B). Sodium; Nikkor SMT manufactured by Nikko Chemicals Co., Ltd., and paraffin wax (paraffin wax 155 manufactured by Nippon Seiro Co., Ltd.; melting point 69° C., weight average molecular weight 472) as component (C) in the amounts shown in Table 1. The composition was supplied into the body 11 and kneaded while being heated and melted in the case 11 to produce a molten electrospinning composition in a molten state. Fibers were produced by the melt electrospinning method using the melt electrospinning composition in a molten state. The manufacturing conditions were as follows.

[Fiber manufacturing conditions]
・Manufacturing environment: 27°C, 50%RH
-Heating temperature in the housing 11: 220°C
・Discharge rate of the melt R: 1 g/min, 2 g/min, 4 g/min
Applied voltage to the discharge nozzle tip portion 14 (made of stainless steel): 0 kV (grounded to earth)
-Applied voltage to charging electrode 21 (80 mm x 80 mm, thickness 10 mm, made of stainless steel): -40 kV
-Distance between the discharge nozzle tip portion 14 and the collection portion 10D: 600 mm
-Temperature of air flow ejected from the fluid ejection device 23: 350°C
-Flow rate of air flow ejected from the fluid ejection device 23: 320 L/min

[Example 2]
A melt electrospinning composition and fibers were produced in the same manner as in Example 1 except that the contents of the components (A) and (C) were changed to the parts by mass shown in Table 1 below.

[Examples 3 and 4]
Paraffin wax (paraffin wax 125, manufactured by Nippon Seiro Co., Ltd.; melting point 53° C., weight average molecular weight 361) was used as the component (C), and each component was mixed in the parts by mass shown in Table 1 below. A melt electrospinning composition and fibers were produced in the same manner as in 1.

[Comparative Example 1]
A melt electrospinning composition and fibers were produced in the same manner as in Example 1 except that the components (C) were not used and only the components (A) and (B) were mixed in the parts by mass shown in Table 1 below. ..

[Comparative Example 2]
A molten electrospinning composition and fibers were produced in the same manner as in Example 3 except that the component (A) and the component (C) were mixed in the parts by mass shown in Table 1 below without using the component (B). did.

[Comparative Example 3]
Component (A) and polypropylene wax (manufactured by Clariant Co., Ltd., Licocene PP6102; dropping point 145° C., weight average molecular weight measured by high temperature SEC method or high temperature GPC method) without using components (B) and (C). The composition and fiber for melt electrospinning were produced in the same manner as in Example 1 except that the above components were mixed with 5000 parts by weight shown in Table 1 below.

[Evaluation 1: Viscosity of melt]
The viscosities of the melts of the melt electrospinning compositions produced in Examples and Comparative Examples were measured. Specifically, the viscosity (Pa·s) of the melt was measured using a rotary rheometer (MCR302, manufactured by Anton Paar) under the conditions of 200° C. and a shear rate of 10 s ⁻¹ . The results are shown in Table 1 below.

[Evaluation 2: Evaluation of fiber diameter]
In Examples and Comparative Examples, the median fiber diameter of each fiber produced with different spinning amount was evaluated. The fiber diameter was measured by arbitrarily selecting 500 fibers excluding defects such as lumps of fused electrospun fibers, intersections of fused electrospun fibers, and polymer droplets from a two-dimensional image obtained by scanning electron microscope observation, and measuring the length of the fiber. The length when a line orthogonal to the direction was drawn was taken as the fiber diameter. The median fiber diameter (nm) was determined from the distribution of the measured fiber diameters. The results are shown in Table 1 below.

[Evaluation 3: Evaluation of liquid contact angle]
The melts of the compositions for molten electrospinning produced in Examples and Comparative Examples were pressed to prepare resin plates of 250 mm length×250 mm width×1 mm thickness. Pressurization is performed in the order of (1) pre-pressurization: 180°C, 0.5 MPa, 3 min, (2) main pressurization: 180°C, 20 MPa, 2 min, and (3) cooling: 18°C, 0.5 MPa, 1 min I went there. A test piece having a length of 10 mm, a width of 50 mm, and a thickness of 1 mm was cut out from the obtained resin plate with a cutter, and the wet solution tension test mixture No. 1 was applied to the surface of the test piece. 1.5 μL of 33 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., surface tension 33.0 mN/m) was dropped, and the contact angle (°) between the resin plate and the mixed solution was set to 23° C. at the Kyowa Interface. The measurement was performed using Drop Master 300 manufactured by Kagaku Co., Ltd. The larger the contact angle, the higher the hydrophobicity. The results are shown in Table 1 below.

[Evaluation 4: Evaluation of liquid repellency]
In the examples and comparative examples, the fibers produced at a spinning rate of 1 g/min were each formed into a sheet shape to obtain a fiber formed body. The basis weight of each molded body was 7 g/m ² . This molded body was measured to have a size of 50 mm in length×50 mm in width, and both ends of the molded body were sandwiched by SUS plates, and the experimental stand and the molded body were separated from each other and fixed with tension applied to the molded body. Liquid mixture for wet tension test No. was applied to the surface of the fixed molding. 15 μL of 33 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., surface tension: 33.0 mN/m) was dropped, and the liquid repellency 20 seconds after the dropping and 60 seconds after the dropping were visually evaluated according to the following criteria. The results are shown in Table 1 below.

<Evaluation criteria for liquid repellency>
A: The droplets are liquid-repellent without penetrating into the sheet-shaped molded article, and have excellent hydrophobicity.
B: The droplets partially penetrate into the sheet-shaped compact, but most of the droplets remain on the surface of the compact, and the hydrophobicity is high.
C: Some of the droplets remain on the surface of the sheet-shaped molded article, but the droplets have penetrated into the molded article and are inferior in hydrophobicity.
D: All the droplets penetrated into the sheet-shaped molded product, and the hydrophobicity was very poor.

As shown in Table 1, in Examples containing components (A) to (C) in a predetermined ratio, as compared with Comparative Examples, fine fibers can be efficiently spun without depending on the amount of spinning, and It can be seen that the obtained fibers are highly hydrophobic. In particular, as shown in Examples 3 and 4, the higher the content of the component (C), the smaller the fiber diameter of the spun fiber, and the higher the hydrophobicity of the fiber. I understand. On the other hand, the melts of Comparative Examples 2 and 3 have low viscosities, but it can be seen that fine fibers cannot be spun. The reason for this is that the melts of Comparative Examples 2 and 3 do not contain the component (B), and therefore it is considered that the charge amount of the melt in the melt electrospinning is not sufficient.

10 Manufacturing Equipment 11 Housing 12 Discharge Nozzle 13 Nozzle Base 14 Discharge Nozzle Tip 19 Hopper 21 Charging Electrode 22 High Voltage Generator 23 Fluid Injector 24 Collection Sheet 25 Transport Conveyor 26 High Voltage Generator 27 Collection Electrode 1P Melting Electric Field Spinning Composition A Airflow F Fiber R Melt Electrospinning Composition Melt

Claims (9)

Including the following components (A), (B) and (C):
A composition for melt electrospinning in which the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the following components (A), (B) and (C). ..
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax. The component (B) is an alkyl sulfate, an alkyl ether sulfate, an alkyl sulfonate, an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, an olefin sulfonate, and an N-alkyl-N-acylaminoalkyl sulfonate. The composition for melt electrospinning according to claim 1, which is at least one of the above. The composition for melt electrospinning according to claim 1 or 2, wherein the component (C) is a paraffin wax or a microcrystalline wax. The composition for melt electrospinning according to any one of claims 1 to 3, wherein the melting point or dropping point of the component (C) is 50°C or higher and 120°C or lower. Including the following components (A), (B) and (C):
The content of the component (C) is 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the total amount of the components (A), (B) and (C).
A fiber having a median diameter of 0.4 μm or more and 3 μm or less.
(A) Polyolefin resin.
(B) At least one of a sulfate ester salt and a sulfonate salt.
(C) Petroleum wax. A method for producing a fiber, which comprises discharging a molten liquid of the composition for molten electrospinning according to any one of claims 1 to 4 into an electric field and spinning by an electrospinning method. The discharge nozzle that discharges the molten liquid is grounded, and the charging electrode that is arranged apart from the discharge nozzle is connected to a high voltage generator to generate the electric field between the discharge nozzle and the charging electrode. The method for producing a fiber according to claim 6, wherein Separately from the discharge nozzle and the charging electrode, a collecting part for collecting fibers generated from the composition for molten electrospinning is used, and the collecting part is electrically connected to the collecting part. The method for producing a fiber according to claim 6 or 7, wherein the fiber is collected. The method for producing a fiber according to claim 6, wherein a heating fluid is sprayed toward the melt discharged from the discharge nozzle to convey the fiber generated from the melt.

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