JP7245048B2 - MELT ELECTROSPINN COMPOSITION AND FIBERS AND METHOD FOR MANUFACTURE THEREOF - Google Patents

Description

The present invention relates to melt electrospinning compositions. The present invention also relates to fibers and methods of making them.

In recent years, various proposals have been made regarding an electrospinning method (hereinafter also referred to as a melt electrospinning method) for producing fine-diameter fibers using a molten resin. Patent Document 1 discloses a method of heating and melting a polyolefin resin composition containing 0.01 to 1 part by weight of a hindered amine additive with respect to 100 parts by weight of a polyolefin resin, and spinning by an electrospinning method. there is

In addition, the present applicant has previously proposed a method for producing fibers by electrospinning using a mixture containing a resin having a melting point and an additive such as an alkylsulfonate (see Patent Document 2). This production method can stably charge the raw material resin and electrospun fine-diameter fibers.

JP 2015-161051 A JP 2017-190552 A

By the way, fine-diameter fibers are used in various fields, and further reduction in fiber diameter and improvement in surface physical properties of fibers are desired. In the melt electrospinning method, in order to efficiently produce a fiber having a smaller diameter and desired surface properties, an additive for expressing the desired surface properties is used, and a molten resin containing the additive is used. It is necessary to enhance the chargeability and fluidity of the toner. Although the methods described in Patent Documents 1 and 2 can produce fine-diameter fibers, further reduction in the diameter of the produced fibers and development of desired surface physical properties of the fibers, especially hydrophilicity on the fiber surface. There is room for improvement regarding compatibility with expression.

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

The present invention includes the following component (A), component (B) and component (C),
A composition for melt electrospinning, wherein the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the total of the following component (A), the following component (B) and the following component (C). It provides
(A) Polyolefin resin.
(B) at least one of sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax;

The present invention also includes the following component (A), component (B) and component (C),
The content of the component (C) with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C) is 1 part by mass or more and 20 parts by mass or less,
A fiber having a median diameter of 0.4 μm or more and 3 μm or less is provided.
(A) Polyolefin resin.
(B) at least one of sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax;

The present invention also provides a method for producing fibers, wherein the melt of the composition for melt electrospinning is discharged into an electric field and spun by an electrospinning method.

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

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 comprises a polyolefin resin as component (A), at least one of sulfate and sulfonate as component (B), and polyolefin wax and modified polyolefin wax as component (C). and at least one of them, and the component (C) in a predetermined proportion. Melt electrospinning is a process in which a melt containing a resin, which is the raw material of fibers, is extruded into an electric field while a high voltage is being applied. It is a method that can be formed.

The polyolefin resin as component (A) has fiber-forming properties in melt electrospinning and has a melting point. A resin that "has a melting point" means that when the resin to be measured is heated in the differential scanning calorimetry (DSC method), the phase changes from solid to liquid before the resin thermally decomposes. It is a resin that exhibits an endothermic peak due to The weight average molecular weight of 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 determined, for example, using a high temperature size exclusion chromatography (high temperature SEC) method or a high temperature gel permeation chromatography (high temperature GPC) method described in JP-A-2014-129614, and the weight average molecular weight is known and Polystyrene standard samples with different weight average molecular weights (for example, monodisperse polystyrene manufactured by Tosoh Corporation (model numbers: F450, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000, A500 and A300 )) 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 results of the measurement sample are compared with the calibration curve.

Examples of polyolefin resins include polyethylene resins, polypropylene resins, ethylene-α-olefin copolymer resins, ethylene-propylene copolymers, and the like. These resins can be used singly or in combination of two or more. Melt electrospinning can be efficiently performed by using these resins.

At least one of the sulfate ester salt and sulfonate of component (B) modifies polyolefin resin, which is generally hydrophobic, to develop a high charge amount in an electric field, thereby enabling fine-diameter fibers to be formed in an electric field. It is used to make spinnable and to make the surface properties of spun fibers hydrophilic. From the viewpoint of further improving the charge amount of the polyolefin resin and improving the spinnability, the melting point of the component (B) is preferably equal to or lower than the melting point of the polyolefin resin used in combination. The hydrophilicity expressed in the fibers means that the dispersibility of the fibers in water or aqueous liquids is increased, and the retention of water or aqueous liquids between fibers is increased. Hydrophilicity can be evaluated, for example, by using a contact angle and liquid wettability as indicators, as described in detail in the examples below.

The sulfate used in the present invention is a kind of anionic surfactant. A 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. Examples of such sulfates include alkyl sulfates such as higher alcohol sulfates (R—O—SO ₃ M), polyoxyethylene alkyl ether sulfates (R—O—(CH ₂ CH ₂ O) and alkyl ether sulfates such as _n -SO ₃ M). These can be used individually or in combination of 2 or more types.

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

Examples of such sulfonates include alkylsulfonates (R—SO ₃ M), alkylbenzenesulfonates (R—Ph—SO ₃ M), alkylnaphthalenesulfonates (R—Np—SO ₃ M ), olefin sulfonates (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), dialkylsulfosuccinate (R—OOC—CH ₂ —CH(—SO ₃ M)—COO—R), α-sulfo fatty acid ester salt (R- CH(--SO ₃ M)--COO--CH ₃ ), acyl isethionate (R--CO--O--(CH ₂ CH ₂ )--SO ₃ M), acyl taurate (R--CO--NH--(CH ₂ ) ₂ -SO ₃ M), N-alkyl-N-acylaminoalkylsulfonates such as acylalkyl taurine salts (R—CO—N(—R′)—(CH ₂ ) ₂ —SO ₃ M), β- Naphthalenesulfonate formalin condensate (M—O ₃ S—Np—(CH ₂ —Np(—SO ₃ M)) _n —H) and the like. These can be used individually or in combination of 2 or more types.

In the above-mentioned sulfate ester salts and sulfonates, R represents a straight-chain or branched-chain alkyl group, and preferably has 8 or more carbon atoms, more preferably 10 or more carbon atoms, and still more preferably 12 or more carbon atoms, and is preferably is 22 or less, more preferably 20 or less, and still more preferably 18 or less. R' represents a linear or branched alkyl group, preferably having 5 or less carbon atoms. Ph represents an optionally substituted phenyl group. Np represents an optionally substituted naphthyl group. M represents a monovalent cation, preferably a metal ion, 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. These sulfate ester salts and sulfonates may be used singly or as a mixture of two or more thereof.

Of these sulfates and sulfonates, alkyl sulfates, alkyl ether sulfates, alkylsulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, olefinsulfonates, and N-alkyl-N-acyl At least one aminoalkylsulfonate is preferably used, and N-alkyl-N-acylaminoalkylsulfonate is more preferably used. By using such a component as component (B), fibers having a small fiber diameter can be melt electrospun more efficiently, and hydrophilicity is imparted to the surface of the spun fibers.

At least one of the polyolefin wax and the modified polyolefin wax, which are the component (C), affects the hydrophilization of the fiber surface by the component (B) when the composition for melt electrospinning of the present invention is melted and subjected to electrospinning. It is used to increase the fluidity of the melted composition without affecting the , thereby making it possible to produce finer fibers. The component (C) has a weight average molecular weight smaller than that of the component (A). Specifically, it is preferably 600 or more, more preferably 1000 or more, still more preferably 1000 or more, and still more preferably 2000 or more. Also, it is preferably 20,000 or less, more preferably 10,000 or less, still more preferably 9,000 or less, and still more preferably 8,000 or less. The weight average molecular weight can be measured, for example, by the same method as for component (A) described above.

The polyolefin wax used in the present invention refers to a compound composed of one or more linear or branched or cyclic or acyclic saturated aliphatic hydrocarbons, preferably linear or branched. is a non-cyclic alkane. Polyolefin waxes include, for example, polyethylene wax represented by H—(CH ₂ —CH ₂ ) _q —H, polypropylene wax represented by H—(CH ₂ —CH(CH ₃ )) _q —H, H— (CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —H and H— (CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —H, and the like. These can be used individually or in combination of 2 or more types.

In each chemical formula of the polyolefin wax described above, q is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and is preferably 500 or less, more preferably 250 or less, and still more preferably 220 or less. represents the number of r and s are each positive numbers, and the sum of r and s is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 Hereinafter, more preferably, it represents a number of 220 or less. t is preferably 12 or more, more preferably 24 or more, still more preferably 50 or more, and preferably 250 or less, more preferably 125 or less, still more preferably 110 or less.

The modified polyolefin wax used in the present invention is obtained by oxidizing a straight or branched hydrocarbon to have an anionic group such as a carboxy group at any position in the polyolefin wax molecular chain (hereinafter referred to as " Also referred to as "oxidized polyolefin wax"), or those having a carboxy group anhydride at any position in the polyolefin wax molecular chain by graft polymerization of polyolefin wax and maleic anhydride (hereinafter referred to as "acid-modified polyolefin wax ).

Modified polyolefin waxes include, for example, an oxidized polyethylene wax represented by HOOC--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --COOH, and a polyethylene wax molecular chain represented by H--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --H. acid-modified polyethylene wax having a carboxyl anhydride at the position of HOOC-(CH ₂ -CH(CH ₃ )) _q -COOH oxidized polypropylene wax represented by H-(CH ₂ -CH(CH ₃ )) HOOC—(CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s Acid-modified polypropylene wax having a carboxyl anhydride at any position on the polypropylene wax molecular chain represented by _q —H —COOH, HOOC-(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —COOH and HOOC-(CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —COOH Represented ethylene oxide-propylene copolymer wax, H—(CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s — (CH ₂ —CH ₂ ) _r —H and H—(CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —H at any position of the ethylene-propylene copolymer wax molecular chain. Examples include acid-modified ethylene-propylene copolymer waxes having an anhydride group. q, r, s and t each independently represent the same number as in the polyolefin wax described above. These waxes can be used alone or in combination of two or more.

Among these polyolefin waxes and modified polyolefin waxes, polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, oxidized polyethylene wax, acid-modified polyethylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, ethylene oxide-propylene copolymer wax, and acid-modified ethylene-propylene copolymer wax, and more preferably at least one of polypropylene wax and ethylene-propylene copolymer wax. 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 the discharge and drawing can be performed efficiently. As a result, finer fibers can be produced with high production efficiency.

From the viewpoint of stably performing melt electrospinning, the content of component (A) contained in the composition for melt electrospinning is 100 parts by mass in total of component (A), component (B) and component (C). is preferably 70 parts by mass or more, more preferably 75 parts by mass or more, still more preferably 80 parts by mass or more, and preferably 98 parts by mass or less, 97 parts by mass It is more preferably 90 parts by mass or less, more preferably 90 parts by mass or less.

From the viewpoint of achieving both an improvement in the production efficiency of small-diameter fibers and the manifestation of hydrophilicity of the produced small-diameter fibers, the content of component (B) contained in the composition for melt electrospinning is , With respect to 100 parts by mass of the total component (B) and component (C), it is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and further preferably 5 parts by mass or more. It is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less.

From the viewpoint of increasing the fluidity of the melted composition and making it possible to produce fibers with a smaller diameter, the content of component (C) contained in the composition for melt electrospinning is ) and component (C) in an amount of 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, and It is preferably 20 parts by mass or less, more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or less.

In addition, from the viewpoint of further increasing the fluidity of the melted composition to achieve both a further reduction in fiber diameter and a further increase in the production amount of the fiber, the melting point or dropping point of component (C) is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 120°C or higher, and preferably 170°C or lower, more preferably 160°C or lower; It is more preferably 150° C. or less. The melting point or 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). can.

In the melt electrospinning composition of the present invention, in addition to the above-described components (A), (B), and (C), as long as the effects of the present invention are not impaired, an additive is added as component (D). can also be used as Examples of additives that are component (D) include antioxidants, light stabilizers, ultraviolet absorbers, and metal deactivators. Examples of antioxidants include phenol-based antioxidants, phosphite-based antioxidants, and thio-based antioxidants. Examples of light stabilizers and ultraviolet absorbers include hindered amines, nickel complex compounds, benzotriazoles, benzophenones and the like. Examples of metal deactivators include phosphones, epoxies, triazoles, hydrazides, oxamides and the like. These additives can be used alone or in combination of two or more. When the melt electrospinning composition further contains the component (D), the content of the component (D) contained in the composition is the component (A), the component (B), the component (C) and the component (D) It is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and preferably 10 parts by mass or less, with respect to 100 parts by mass of the total components of 1 part by mass More preferably: In this case, each component of component (A), component (B) and component (C) is the content per 100 parts by mass of the total component of component (A), component (B), component (C) and component (D) should be within the range described above.

The method for producing the melt electrospinning composition is not particularly limited. For example, component (B) and component (C) are added to component (A) melted by heating, and component (D) is added if necessary. can be further added and kneaded. Such a composition for melt electrospinning may be produced as a masterbatch by adding component (B) and component (C) to pre-melted component (A) and kneading them. , Component (A), Component (B) and Component (C) may be individually supplied to a production apparatus described later, and kneaded while being heated and melted in the apparatus. When the composition for melt electrospinning is produced as a masterbatch, it can be cooled, molded into a shape such as pellets, and stored as a solid.

According to the composition for melt electrospinning having the above configuration, by including the component (A) and the component (B), the melted composition is suitable for electrospinning without impairing the properties of the composition. By imparting an amount of charge, it is possible to improve the production efficiency of the fiber, reduce the diameter of the spun fiber, and make the surface of the spun fiber express hydrophilicity. In addition, by including the component (C) in the composition in a predetermined proportion, the viscosity of the melted composition is lowered and the fluidity is increased, and the component (B) is added to the component (A). can be separated or dispersed to increase the charge of the composition during electrospinning. As a result, it is possible to produce a fiber having a smaller diameter and exhibiting hydrophilicity. In particular, according to a preferred embodiment of the composition for melt electrospinning, improvement in fiber production efficiency, reduction in the diameter of the spun fiber, and development of the hydrophilicity of the spun fiber are all achieved at a high level. become a thing.

The above description was about the composition for melt electrospinning, and the method for producing fibers using the composition for melt electrospinning will be described below. In this method, a melt electrospinning composition containing the above-described component (A), component (B) and component (C) and containing component (C) in a predetermined ratio is spun by a melt electrospinning method. be.

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

The manufacturing apparatus 10 includes a molten composition supply section 10A. The melted composition supply unit 10A includes a housing 11 having a discharge nozzle 12 for discharging the melt of the melted electrospinning composition described above and a hopper 19 for supplying the melted electrospinning composition 1P.

In the housing 11, the molten electrospinning composition 1P supplied from the hopper 19 can be heated and melted in the housing 11 to obtain a melt R of the molten electrospinning composition. A screw (not shown) provided in the housing 11 allows the melt R to be supplied in the direction of a discharge nozzle 12, which will be described later.

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

The discharge nozzle tip portion 14 is heated, for example, by heat transfer from a heater (not shown) provided on 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 is preferably 100° C. or higher, more preferably 200° C. or higher, and preferably 450° C. or lower, although it depends on the constituent components of the melt electrospinning composition. It is preferably 400° C. or less.

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

The charging electrode 21 is arranged at a position a predetermined distance away from the discharge nozzle tip 14 so as to face the discharge nozzle tip 14 . With this configuration, an electric field is generated between the tip portion 14 of the ejection nozzle 12 and the charging electrode 21 to which a high voltage is applied by the high voltage generator 22, and the melt ejected from the tip portion 14 of the ejection nozzle is 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 desired fiber diameter (diameter) of the fibers and the accumulation property on the collection electrode 27 described later, but is preferably 10 mm or more, more preferably 30 mm or more, preferably 30 mm or more. It is 150 mm or less, more preferably 75 mm or less. When the distance between the ejection nozzle 12 and the charging electrode 21 is within this range, the molten liquid R can be sufficiently charged in the electric field, and sparks and corona discharges can occur between the ejection 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 section 10C. The fluid injection section 10C includes a fluid injection device 23 below the imaginary straight line connecting the molten composition supply section 10A and the electrode section 10B. The fluid injection device 23 is provided between the molten composition supply section 10A and the electrode section 10B.

An airflow A flows between the tip of the ejection nozzle tip portion 14 and the charging electrode 21 in a direction crossing the direction connecting the two. This airflow A is ejected from the fluid ejection device 23 . The melt R discharged from the discharge nozzle tip portion 14 can be conveyed by the air flow A to form even finer fibers. Air, which is a heating fluid, is preferably used as the air flow A for this purpose. The temperature of the heated air is preferably 100° C. or higher, more preferably 200° C. or higher, and is preferably 500° C. or lower, more preferably 400° C., depending on the components of the melt electrospinning composition. It is below. For the same purpose, the flow rate of the airflow A at the discharge port of the fluid injection device 23 when the airflow A is jetted is preferably 50 L/min or more, more preferably 150 L/min or more. is 500 L/min or less, more preferably 400 L/min or less.

The manufacturing apparatus 10 further includes a collecting section 10D. The collection section 10</b>D includes a collection sheet 24 , a conveyer 25 , a high voltage generator 26 and a collection electrode 27 . The collection section 10D is provided at a position above the imaginary straight line connecting the molten composition supply section 10A and the electrode section 10B and at a position facing the fluid injection section 10C. The collection units 10D are electrically connected to each other.

The collection sheet 24 collects the fibers F that are conveyed by the air flow A and stretched. The collection sheet 24 can be, for example, a long strip. The collection sheet 24 is unwound from the original fabric roll 24 a and conveyed to the conveyer 25 . The collection sheet 24 can be made of resin such as polypropylene.

A transport conveyor 25 transports the molten electrospun fibers to the downstream manufacturing process. A collecting electrode 27 for collecting melt electrospun fibers is arranged inside the conveyer 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 collection electrode 27 , the fibers F are attracted toward the negatively charged transport conveyor 25 and deposited on the surface of the collection sheet 24 . Also, the collection electrode 27 may be grounded instead of the high voltage generator 26 .

The manufacturing apparatus 10 shown in FIG. 1 has been described above, and the method for manufacturing fibers 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 tip portion 14 of the discharge nozzle.

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

From the viewpoint of making it easier to stretch the melt R during electrospinning and making the fibers to be produced smaller in diameter, the viscosity of the melt of the composition for melt electrospinning is set at 200° C. and a shear rate of 10 s ⁻¹ . Regarding the conditions, it is preferably 1 Pa·s or more, more preferably 4 Pa·s or more, and preferably 10 Pa·s or less, 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 point of view, it is preferable to set the melt flow rate (MFR) of the melted melt electrospinning composition to 10 g/min or more, particularly 100 g/min or more at the discharge port of the discharge nozzle tip 14 . Melt flow rate (MFR) is measured according to JIS K 7210, for example, when polypropylene resin is used as 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. measured by

From the viewpoint of achieving both efficient stretching of the melt R and fiber manufacturing efficiency, the discharge rate of the molten composition for melt electrospinning is preferably 1 g/min or more, and is 2 g/min or more. is more preferably 20 g/min or less, and more preferably 5 g/min or less.

After that, the melt R discharged from the discharge nozzle tip portion 14 is further stretched by further blowing the airflow A toward the melt R from the fluid injection device 23, and the melt R is transported while producing ultrafine fibers. be. The melt R ejected from the ejection nozzle tip portion 14 is transported by the air flow A before reaching the charging electrode 21, so that the flying direction of the melt R is changed and the melt R is stretched to form an ultrafine particle. Fibers F are produced by curing and solidifying. The fibers F generated from the melt R are transported by the airflow A, attracted by the electrical attraction generated in the collection electrode 27, and deposited on the surface of the collection sheet 24 facing the fluid injection device 23. .

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

In this manufacturing method, the melt R ejected from the ejection nozzle 12 is highly charged due to being ejected into an electric field. The charge amount of the melt R is preferably as high as possible from the viewpoint of ultrafine fibers by electrospinning. Specifically, it is preferably 2000 nC/g or more, more preferably 3000 nC/g or more. , more preferably 5000 nC/g or more, more preferably 9000 nC/g or more. For such a charge amount, the component (B) in the composition for melt electrospinning is used as described above, and the contents of component (A), component (B) and component (C) are within the ranges described above. can be achieved by The charge amount of the melt R can be measured by, for example, collecting the charged melt R in a metal container placed in a Faraday cage (manufactured by Kasuga Denki Co., Ltd., KQ1400) for 1 minute, and measuring a coulomb meter (Kasuga Denki) connected to the Faraday cage. NK-1002A manufactured by Denki Co., Ltd.) can be used for measurement. The measurement conditions are 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 fibers thus produced are considered as one continuous fiber from the discharge nozzle 12 to the collection sheet 24 . Even if the fibers are temporarily cut due to manufacturing conditions, the surrounding environment, etc., the cut fibers will soon come into contact with each other, and as a result, the ultrafine fibers will flow from the discharge nozzle 12 to the collection sheet 24. It is considered that the fiber is formed as if it were a single continuous fiber between.

The fiber produced through the above steps is spun from the melt electrospinning composition containing the above-described component (A), component (B) and component (C) as a raw material, and is obtained by melt electrospinning. Since there is substantially no deterioration 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-described 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) , the content of component (C) is preferably 1 part by mass or more and 20 parts by mass or less. In addition, the above description of the composition for melt electrospinning is appropriately applied to the description of 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, fibers having a desired fiber diameter and fiber length can be produced depending on the conditions under which the melt electrospinning method is carried out. In particular, fibers with an extremely small fiber diameter called nanofibers can be produced. The fiber diameter of the fiber of the present invention is preferably 0.4 μm or more, more preferably 3 μm or less, more preferably 1 μm or less, when the fiber diameter is expressed as a circle equivalent diameter. . The median fiber length of the fibers of the present invention is preferably 10 mm or longer, more preferably 50 mm or longer, and even more preferably 100 mm or longer.

The fiber diameter and fiber length of the fibers produced by the melt electrospinning method can be determined, for example, from a two-dimensional image observed with a scanning electron microscope (SEM), such as melt electrospun fiber clumps, melt electrospun fiber intersections, and polymer droplets. Randomly select 500 fibers without defects, take the length of a line perpendicular to the longitudinal direction of the fiber as the fiber diameter, and measure the length in the longitudinal direction of the fiber as the fiber length. can be done. The median fiber diameter can be determined from the measured fiber diameter distribution, and the median fiber length can be determined from the measured fiber length distribution.

From the viewpoint of more effectively expressing hydrophilicity on the fiber surface, the fiber of the present invention is preferably subjected to a heat treatment. The method of heat treatment of the fibers is not particularly limited, but for example, a method of blowing hot air onto the fibers, a method of irradiating the fibers with infrared rays, a method of immersing the fibers in a heated liquid such as hot water, and a pair of heated rolls. Examples include a method of passing fibers between them, a method of holding fibers in a heated space such as a constant temperature bath, and a method of pressing fibers by sandwiching them between heated metal plates. These methods may be performed on the spun fiber as it is, may be performed at the same time as forming the fiber into a predetermined shape to form a fiber molded article, or may be performed after forming the molded article. good.

From the viewpoint of enhancing the hydrophilicity of the fibers and increasing the rigidity of the fibers, it is preferable to heat the fibers at a temperature not higher than the melting point of the component (A) when the heat treatment is performed. Specifically, when the melting point of component (A) is MP (°C), it is preferably (MP-100)°C or higher, more preferably (MP-80)°C or higher, and still more preferably (MP-60)°C. Above, it is more preferably (MP-40)°C or higher, and more preferably (MP-10)°C or lower. From the same point of view, for example, 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, preferably 30 minutes or less, more preferably 30 minutes or less. is less than 20 minutes.

As component (A), for example, when polypropylene (melting point: about 150° C.) is included as a thermoplastic resin, the heating temperature is preferably 50° C. or higher, more preferably 70° C. or higher, still more preferably 90° C. or higher, and , preferably 140° C. or less. From the same point of view, for example, 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, preferably 30 minutes or less, and further It is preferably 20 minutes or less.

The fiber obtained by the present invention has a hydrophilic surface and a small fiber diameter. The fiber of the present invention can be used for various purposes as it is or as a molded article of fibers in which fibers are accumulated. Examples of the shape of the molded product include sheet-like, cotton-like, filament-like, and the like. The fiber molding may be used by being laminated with other sheets, or containing various liquids, fine particles, fibers, and the like. A sheet-shaped body of fibers spun by the melt electrospinning method can be used as textile products such as woven fabrics and non-woven fabrics as long fibers and short fibers. It is suitably used as a sheet to be adhered to the skin, teeth, gums, hair of non-human mammals, teeth, gums, plant surfaces such as branches and leaves, and the like. It is also suitable for high-performance filters with high dust collection and low pressure loss, separators for batteries that can be used at high current densities, cell culture substrates with a high pore structure, and the like. A cotton-like body of molten electrospun fibers is suitably used as a soundproofing material, a heat insulating material, or the like. In addition to the above uses, it can also be used for electromagnetic wave shielding materials, bioartificial equipment, IC chips, organic EL, solar cells, electrochromic display elements, photoelectric conversion elements, 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, the manufacturing apparatus 10 shown in FIG. 1 has the molten composition supply section 10A and the fluid injection section 10C separately, but instead of this, the fluid injection section 10C is incorporated into the molten composition supply section 10A. good too. Specifically, as shown in Japanese Unexamined Patent Application Publication No. 2016-204816, a nozzle for discharging a melt of a melt electrospinning composition, an electrode for generating an electric field between the nozzle, and a voltage is applied to the electrode. and a collection unit for collecting fibers generated from the melt electrospinning composition, and a flow path through which the melt can flow is formed between the housing and the nozzle, The manufacturing apparatus may have a fluid ejector formed so as to surround the flow path. In this case, instead of the electrode part 10B, a voltage is applied to the collecting electrode 27 in the collecting part 10D to generate an electric field between it and the nozzle. The melt may be directly discharged from the nozzle. The fluid injection part 10</b>C in this embodiment can inject the airflow A along the direction in which the melt R is discharged from the discharge nozzle 12 .

In addition, in the manufacturing apparatus 10 shown in FIG. 1, the electrode for generating an electric field between the discharge nozzle 12 and the discharge nozzle 12 is provided separately from the molten composition supply section 10A as the charging electrode 21. A charging electrode 21 may be incorporated into the composition supply section 10A. Specifically, as disclosed in Japanese Patent Application Laid-Open No. 2016-204816, the charging electrode 21 is a concave surface electrode having a concave surface arranged so as to surround the discharge 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 suction means such as a suction box that is not electrically connected, instead of the collection electrode 27, so that the spun fibers F are collected. may be suctioned to deposit the fibers onto the collection sheet 24 .

With respect to the above-described embodiments, the present invention further discloses the following melt electrospinning compositions, fibers, and methods for producing fibers.
<1>
including the following components (A), components (B) and components (C),
A composition for melt electrospinning, wherein the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the total of the following component (A), the following component (B) and the following component (C). .
(A) Polyolefin resin.
(B) at least one of sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax;

<2>
Component (B) is alkyl sulfate, alkyl ether sulfate, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, olefin sulfonate, and N-alkyl-N-acylaminoalkyl sulfonate The melt electrospinning composition according to <1> above, which is at least one of
<3>
The component (C) is polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, oxidized polyethylene wax, acid-modified polyethylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, ethylene oxide-propylene copolymer wax and acid-modified ethylene- The melt electrospinning composition according to <1> or <2>, which is at least one of propylene copolymer waxes.
<4>
The melt electrospinning composition according to any one of <1> to <3>, wherein the component (C) has a melting point or dropping point of 90°C or higher and 150°C or lower.

<5>
The component (C) has a weight average molecular weight smaller than that of the component (A), preferably 600 or more, more preferably 1000 or more, still more preferably 1000 or more, still more preferably 2000 or more, and preferably is 20,000 or less, more preferably 10,000 or less, still more preferably 9,000 or less, and still more preferably 8,000 or less.
<6>
The component (C) contains a polyolefin wax,
The polyolefin wax refers to a synthetic product composed of one or more linear or branched or cyclic or acyclic saturated aliphatic hydrocarbons, preferably linear or branched and noncyclic. The composition for melt electrospinning according to any one of <1> to <5>, which is an alkane of the formula:

<7>
The component (C) contains a polyolefin wax,
The polyolefin waxes include a polyethylene wax represented by H—(CH ₂ —CH ₂ ) _q —H, a polypropylene wax represented by H—(CH ₂ —CH(CH ₃ )) _q —H, and H—( CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —H and H—( at least one ethylene-propylene copolymer wax represented by CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —H;
q is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 or less, still more preferably 220 or less,
r and s are each positive numbers, and the sum of r and s is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 hereinafter, more preferably represents a number of 220 or less,
t is preferably 12 or more, more preferably 24 or more, still more preferably 50 or more, and preferably 250 or less, more preferably 125 or less, still more preferably 110 or less, <1> The composition for melt electrospinning according to any one of <6>.

<8>
The component (C) contains a modified polyolefin wax,
The modified polyolefin wax is an oxidized polyethylene wax represented by HOOC--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --COOH, and a polyethylene wax represented by H--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --H. acid-modified polyethylene wax having a carboxy group anhydride in HOOC-(CH ₂ -CH(CH ₃ )) _q -COOH oxidized polypropylene wax represented by H-(CH ₂ -CH(CH ₃ )) _q - HOOC-(CH ₂ -CH ₂ ) _r -(CH ₂ -CH(CH ₃ )) _s -COOH, an acid-modified polypropylene wax having a carboxyl anhydride at any position on the polypropylene wax molecular chain represented by H , HOOC-(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —COOH and HOOC-(CH ₂ —CH _{2 —CH 2} —CH(CH ₃ )) _t —COOH and H—(CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s —( CH ₂ —CH ₂ ) _r —H and H—(CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —A carboxy group at any position of the ethylene-propylene copolymer wax molecular chain represented by —H at least one acid-modified ethylene-propylene copolymer wax having an anhydride of
q is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 or less, still more preferably 220 or less,
r and s are each positive numbers, and the sum of r and s is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 hereinafter, more preferably represents a number of 220 or less,
t is preferably 12 or more, more preferably 24 or more, still more preferably 50 or more, and preferably 250 or less, more preferably 125 or less, still more preferably 110 or less, <1> The composition for melt electrospinning according to any one of <7>.

<9>
The melt electrospinning composition according to any one of <1> to <8>, wherein the component (C) is more preferably at least one of polypropylene wax and ethylene-propylene copolymer wax.
<10>
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 component of the component (A), the component (B) and the component (C). It is more preferably at least 80 parts by mass, further preferably at least 80 parts by mass, preferably at most 98 parts by mass, more preferably at most 97 parts by mass, and preferably at most 90 parts by mass. More preferably, the composition for melt electrospinning according to any one of <1> to <9>.
<11>
The content of the component (B) is preferably 2 parts by mass or more, and 4 parts by mass with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C). It is more preferably at least 5 parts by mass, further preferably at least 5 parts by mass, preferably at most 10 parts by mass, more preferably at most 8 parts by mass, and preferably at most 6 parts by mass. More preferably, the composition for melt electrospinning according to any one of <1> to <10>.

<12>
The content of the component (C) is preferably 1 part by mass or more, and 5 parts by mass with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C). It is more preferably at least 7 parts by mass, further preferably at least 7 parts by mass, preferably at most 20 parts by mass, more preferably at most 17 parts by mass, and preferably at most 15 parts by mass. More preferably, the composition for melt electrospinning according to any one of <1> to <11>.
<13>
further comprising an additive containing at least one of an antioxidant, a light stabilizer, an ultraviolet absorber, and a metal deactivator as component (D),
The content of the component (D) is 0.01 parts by mass or more with respect to 100 parts by mass of the total component of the component (A), the component (B), the component (C) and the component (D). preferably 0.05 parts by mass or more, preferably 10 parts by mass or less, and further preferably 1 part by mass or less, of the above <1> to <12> Melt electrospinning composition according to any one of the preceding claims.

<14>
A method for producing a fiber, wherein the melt of the composition for melt electrospinning according to any one of <1> to <13> is discharged into an electric field and spun by an electrospinning method.
<15>
The discharge nozzle for discharging the melt is grounded, and a charged electrode spaced apart from the discharge nozzle is connected to a high voltage generator to generate the electric field between the discharge nozzle and the charged electrode. The method for producing a fiber according to <14> above.
<16>
Separately from the discharge nozzle and the charging electrode, a collection section for collecting fibers produced from the melt electrospinning composition is used, and the collection section is electrically connected to the collection section. The method for producing a fiber according to <14> or <15> above, wherein the fiber is collected in the above <14> or <15>.
<17>
The method for producing a fiber according to any one of <14> to <16>, wherein a heated fluid is sprayed toward the melt discharged from the discharge nozzle to transport the fiber produced from the melt.

<18>
including the following components (A), components (B) and components (C),
The content of the component (C) with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C) is 1 part by mass or more and 20 parts by mass or less,
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 sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax;
<19>
Component (B) is alkyl sulfate, alkyl ether sulfate, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, olefin sulfonate, and N-alkyl-N-acylaminoalkyl sulfonate The fiber according to <18> above, which is at least one of
<20>
The component (C) is polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, oxidized polyethylene wax, acid-modified polyethylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, ethylene oxide-propylene copolymer wax and acid-modified ethylene- The fiber according to <18> or <19> above, which is at least one type of propylene copolymer wax.

<21>
The fiber according to any one of <18> to <20> above, wherein the component (C) has a melting point or dropping point of 90°C or higher and 150°C or lower.
<22>
The component (C) has a weight average molecular weight smaller than that of the component (A), preferably 600 or more, more preferably 1000 or more, still more preferably 1000 or more, still more preferably 2000 or more, and preferably is 20,000 or less, more preferably 10,000 or less, still more preferably 9,000 or less, and still more preferably 8,000 or less, the fiber according to any one of <18> to <21>.
<23>
The component (C) contains a polyolefin wax,
The polyolefin wax refers to a synthetic product composed of one or more linear or branched or cyclic or acyclic saturated aliphatic hydrocarbons, preferably linear or branched and noncyclic. The fiber according to any one of <18> to <22> above, which is an alkane of the formula:

<24>
The component (C) contains a polyolefin wax,
The polyolefin waxes include a polyethylene wax represented by H—(CH ₂ —CH ₂ ) _q —H, a polypropylene wax represented by H—(CH ₂ —CH(CH ₃ )) _q —H, and H—( CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —H and H—( at least one ethylene-propylene copolymer wax represented by CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —H;
q is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 or less, still more preferably 220 or less,
r and s are each positive numbers, and the sum of r and s is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 hereinafter, more preferably represents a number of 220 or less,
t is preferably 12 or more, more preferably 24 or more, still more preferably 50 or more, and preferably 250 or less, more preferably 125 or less, still more preferably 110 or less, <18> The fiber according to any one of <23>.

<25>
The component (C) contains a modified polyolefin wax,
The modified polyolefin wax is an oxidized polyethylene wax represented by HOOC--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --COOH, and a polyethylene wax represented by H--( _CH.sub.2 -- _CH.sub.2 ) _.sub.q --H. acid-modified polyethylene wax having a carboxy group anhydride in HOOC-(CH ₂ -CH(CH ₃ )) _q -COOH oxidized polypropylene wax represented by H-(CH ₂ -CH(CH ₃ )) _q - HOOC-(CH ₂ -CH ₂ ) _r -(CH ₂ -CH(CH ₃ )) _s -COOH, an acid-modified polypropylene wax having a carboxyl anhydride at any position on the polypropylene wax molecular chain represented by H , HOOC-(CH ₂ —CH(CH ₃ )) _s —(CH ₂ —CH ₂ ) _r —COOH and HOOC-(CH ₂ —CH _{2 —CH 2} —CH(CH ₃ )) _t —COOH ethylene oxide-propylene copolymer wax, and H—(CH ₂ —CH ₂ ) _r —(CH ₂ —CH(CH ₃ )) _s —H, H—(CH ₂ —CH(CH ₃ )) _s —( CH ₂ —CH ₂ ) _r —H and H—(CH ₂ —CH ₂ —CH ₂ —CH(CH ₃ )) _t —A carboxy group at any position of the ethylene-propylene copolymer wax molecular chain represented by —H at least one acid-modified ethylene-propylene copolymer wax having an anhydride of
q is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 or less, still more preferably 220 or less,
r and s are each positive numbers, and the sum of r and s is preferably 24 or more, more preferably 48 or more, still more preferably 100 or more, and preferably 500 or less, more preferably 250 hereinafter, more preferably represents a number of 220 or less,
t is preferably 12 or more, more preferably 24 or more, still more preferably 50 or more, and preferably 250 or less, more preferably 125 or less, still more preferably 110 or less, <18> The fiber according to any one of <24>.

<26>
The fiber according to any one of <18> to <25>, wherein the component (C) is more preferably at least one of polypropylene wax and ethylene-propylene copolymer wax.
<27>
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 component of the component (A), the component (B) and the component (C). It is more preferably at least 80 parts by mass, further preferably at least 80 parts by mass, preferably at most 98 parts by mass, more preferably at most 97 parts by mass, and preferably at most 90 parts by mass. The fiber according to any one of <18> to <26>, which is more preferable.
<28>
The content of the component (B) is preferably 2 parts by mass or more, and 4 parts by mass with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C). It is more preferably at least 5 parts by mass, further preferably at least 5 parts by mass, preferably at most 10 parts by mass, more preferably at most 8 parts by mass, and preferably at most 6 parts by mass. The fiber according to any one of <18> to <27>, which is more preferable.

<29>
The content of the component (C) is preferably 1 part by mass or more, and 5 parts by mass with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C). It is more preferably at least 7 parts by mass, further preferably at least 7 parts by mass, preferably at most 20 parts by mass, more preferably at most 17 parts by mass, and preferably at most 15 parts by mass. The fiber according to any one of <18> to <28>, which is more preferable.
<30>
further comprising an additive containing at least one of an antioxidant, a light stabilizer, an ultraviolet absorber, and a metal deactivator as component (D),
The content of the component (D) is 0.01 parts by mass or more with respect to 100 parts by mass of the total component of the component (A), the component (B), the component (C) and the component (D). is preferably 0.05 parts by mass or more, preferably 10 parts by mass or less, and further preferably 1 part by mass or less, the above <18> to <29> A fiber according to any one of the preceding claims.

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the scope of the invention is not limited to such examples.

[Example 1]
Using the production apparatus 10 shown in FIG. 1, polypropylene resin (PP; manufactured by PolyMirae, MF650Y, weight average molecular weight 79000) as component (A) and acylalkyl taurate salt (N-stearoyl-N- Sodium methyl taurate; Nikko Chemicals Co., Ltd., Nikkor SMT) and polypropylene wax (Clariant Co., Ltd., Licocene PP6102; dropping point 145°C, weight average molecular weight 5000) as component (C). These were fed into the body 11 and kneaded while being heated and melted in the housing 11 to produce a molten electrospinning composition in a molten state. Also, a fiber was produced by a melt electrospinning method using the composition for melt electrospinning in a molten state. The manufacturing conditions were as follows.

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

[Examples 2 to 4]
A melt electrospinning composition and fibers were produced in the same manner as in Example 1, except that the contents of components (A) and (C) were changed to parts by mass shown in Table 1 below.

[Examples 5 and 6]
Ethylene-propylene copolymer wax (Licocene PP1302 manufactured by Clariant Co., Ltd.; dropping point 90° C., weight average molecular weight 6400) was mixed as the component (C) in the parts by mass shown in Table 1 below. Melt electrospinning compositions and fibers were similarly prepared.

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

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

[Comparative Example 3]
Without using component (B) and component (C), component (A) and petroleum wax (paraffin wax 125 manufactured by Nippon Seiro Co., Ltd.; melting point 53 ° C., weight average molecular weight measured by gas chromatography mass spectrometry 361) were mixed in the parts by mass shown in Table 1 below, and a melt electrospinning composition and fibers were produced in the same manner as in Example 1.

[Evaluation 1: Viscosity of melt]
The viscosities of the melts of the melt electrospinning compositions produced in Examples and Comparative Examples were measured. Specifically, using a rotary rheometer (MCR302 manufactured by Anton Paar), the viscosity (Pa·s) of the melt was measured at 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 the Examples and Comparative Examples, the median fiber diameter of each fiber produced at different spinning weights was evaluated. The fiber diameter is measured by arbitrarily selecting 500 fibers from a two-dimensional image obtained by scanning electron microscope observation, excluding defects such as lumps of molten electrospun fibers, intersections of molten electrospun fibers, and polymer droplets. The fiber diameter was defined as the length of a line perpendicular to the direction. A median fiber diameter (nm) was determined from the measured fiber diameter distribution. The results are shown in Table 1 below.

[Evaluation 3: Evaluation of liquid contact angle]
A resin plate of 250 mm long×250 mm wide×1 mm thick was prepared by pressurizing the melt of the molten electrospinning composition produced in Examples and Comparative Examples. Pressurization is (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 with A test piece measuring 10 mm long, 50 mm wide and 1 mm thick was cut out from the obtained resin plate with a cutter. 33 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., surface tension 33.0 mN / m) is dropped 1.5 μL, and the contact angle (°) between the resin plate and the mixed liquid is measured at a temperature of 23 ° C., Kyowa interface It was measured using a Drop Master 300 manufactured by Kagaku Co., Ltd. The lower the contact angle, the higher the hydrophilicity. The results are shown in Table 1 below.

[Evaluation 4: evaluation of liquid wettability]
In the examples and comparative examples, the fibers produced at a spinning rate of 1 g/min were formed into sheets to form fiber molded articles. The basis weight of each molded body was 7 g/m ² . This molded body was sized 50 mm long and 50 mm wide, and both ends of the molded body were sandwiched between SUS plates to separate the test table from the molded body and fix the molded body in a tensioned state. Mixed liquid No. for wet tension test was applied to the surface of the fixed compact. 33 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., surface tension: 33.0 mN/m) was dropped in an amount of 15 μL, and the liquid wettability was visually evaluated 20 seconds after dropping and 60 seconds after dropping according to the following criteria. The results are shown in Table 1 below.

<Evaluation criteria for liquid wettability>
A: All the droplets permeate the sheet-like formed body, and the hydrophilicity is very excellent.
B: Some droplets remain on the surface of the sheet-like molded body, but the droplets permeate the molded body and have hydrophilicity.
C: Droplets partially permeate the sheet-like molded body, but most of the droplets remain on the surface of the molded body, and hydrophilicity is poor.
D: Liquid droplets did not permeate the sheet-like molded article at all, and the sheet-like molded article was liquid-repellent, and the hydrophilicity was very poor.

As shown in Table 1, in the examples containing the components (A) to (C) in a predetermined ratio, compared to the comparative examples, small-diameter fibers can be efficiently spun regardless of the amount of spinning, and the liquid It can be seen that the penetration time of the droplets is very short and the fibers obtained are highly hydrophilic. In particular, as shown in Examples 1, 4 and 5, it can be seen that as the content of component (C) increases, the spun fibers become more hydrophilic and smaller diameter fibers can be produced. In contrast, the melts of Comparative Examples 2 and 3 have low viscosities, but it can be seen that they cannot be spun into small-diameter fibers. A possible reason for this is that the melts of Comparative Examples 2 and 3 do not contain the component (B), so that the charge amount of the melts in the melt electrospinning is insufficient.

REFERENCE SIGNS LIST 10 manufacturing device 11 housing 12 discharge nozzle 13 nozzle base 14 discharge nozzle tip 19 hopper 21 charging electrode 22 high voltage generator 23 fluid injection device 24 collection sheet 25 transport conveyor 26 high voltage generator 27 collection electrode 1P melting electric field Spinning composition A Air flow F Fiber R Melt of melt electrospinning composition

Claims (9)

including the following components (A), components (B) and components (C),
A composition for melt electrospinning, wherein the content of the following component (C) is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the total of the following component (A), the following component (B) and the following component (C). .
(A) Polyolefin resin.
(B) at least one of sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax; Component (B) is an alkyl sulfate, an alkyl ether sulfate, an alkyl sulfonate, an alkylbenzene sulfonate, an alkyl naphthalene 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 component (C) is polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, oxidized polyethylene wax, acid-modified polyethylene wax, oxidized polypropylene wax, acid-modified polypropylene wax, ethylene oxide-propylene copolymer wax and acid-modified ethylene- 3. The composition for melt electrospinning according to claim 1 or 2, which is at least one of propylene copolymer waxes. The composition for melt electrospinning according to any one of claims 1 to 3, wherein the melting point or dropping point of component (C) is 90°C or higher and 150°C or lower. including the following components (A), components (B) and components (C),
The content of the component (C) with respect to 100 parts by mass of the total component of the component (A), the component (B) and the component (C) is 1 part by mass or more and 20 parts by mass or less,
A sheet-like body containing fibers having a median diameter of 0.4 μm or more and 3 μm or less.
(A) Polyolefin resin.
(B) at least one of sulfate ester salts and sulfonates;
(C) at least one of polyolefin wax and modified polyolefin wax; A method for producing a fiber, wherein the melt of the composition for melt electrospinning according to any one of claims 1 to 4 is discharged into an electric field and spun by an electrospinning method. The discharge nozzle for discharging the melt is grounded, and a charged electrode spaced apart from the discharge nozzle is connected to a high voltage generator to generate the electric field between the discharge nozzle and the charged electrode. The method for producing the fiber according to claim 6, wherein Separately from the discharge nozzle and the charging electrode, a collection section for collecting fibers produced from the melt electrospinning composition is used, and the collection section is electrically connected to the collection section. The method for producing fibers according to claim 7 , wherein the fibers are collected in the 9. The method for manufacturing a fiber according to claim 7 , wherein a heating fluid is sprayed toward the melt discharged from the discharge nozzle to convey the fiber produced from the melt.

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