Fiber

Abstract

To provide a fiber in which hydrophobic properties are increased, and a hydrophobic treatment effect is easy to maintain for a long time even in water.SOLUTION: There is provided a fiber which comprises: the following component A by 50 mass% or more; and the following component B by 10 mass% or more with respect to the mass of the entire fiber, and comprises the component A and the component B at the inside of the fiber, and in which the component B is water-insoluble at a solidification point of 30°C or more: the component A is aliphatic polyester, and the component B is one or more kinds of compounds selected from the following (1) to (3): (1) one or more kinds of compounds selected from aliphatic acids with a carbon number of 14 or more to 24 or less; (2) one or more kinds of compounds selected from aliphatic acid ester compounds being aliphatic acid ester compounds obtained by combining polyhydric alcohol and two or more aliphatic acids, in which the total of the carbon numbers in all aliphatic acid groups is 24 or more and a ratio between the number of the aliphatic acid groups and the number of hydroxyl groups (the number of the aliphatic acid groups / the number of hydroxyl groups) is 1 or more; and (3) one or more kinds of compounds selected from sphingolipids with a carbon number of 24 or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to fibers. [Background technology]

[0002] Fibers are used in various fields, such as filters, sanitary materials, cosmetic materials, and medical materials (for example, Patent Documents 1 to 3). Fibers are sometimes used by impregnating them with an active ingredient as a liquid. With the development of spinning technology, many studies have been conducted on producing various fibers, such as ultrafine fibers (for example, fiber diameter of 50 μm or less) from thermoplastic resins, but the surface properties of the fibers are easily influenced by the hydrophobicity of the thermoplastic resin used. Therefore, for example, when a more hydrophobic liquid is quickly impregnated into the fibers to be used in cosmetics, or when crushed fibers are quickly dispersed in a more hydrophobic liquid to be used as a filler in a thin film, the uses of the prepared fibers are limited if the thermoplastic resin itself remains hydrophobic. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2013-520583 [Patent Document 2] International Publication No. 2006 / 022430 [Patent Document 3] International Publication No. 2019 / 235543 Summary of the Invention [Problem to be solved by the invention]

[0004] When the above-mentioned fibers are used in vivo or on the skin, aliphatic polyesters may be preferably used as the specific material of the fibers. The hydrophobicity of the surface of fibers using aliphatic polyesters may be insufficient in terms of affinity with more hydrophobic liquids. Conventionally, in order to further increase the hydrophobicity of the fiber surface, it has been common to apply a hydrophobizing agent. However, since the hydrophobization is performed by coating or impregnation treatment, when the fiber is in water, the hydrophobizing agent is detached from the surface, and the hydrophobizing effect is inevitably reduced, leaving room for improvement. In view of the above, the present invention relates to a fiber having enhanced hydrophobicity and capable of easily maintaining the hydrophobic treatment effect for a long time even in water. [Means for solving the problem]

[0005] The present invention provides a fiber comprising 50% by mass or more of the following component A and 10% by mass or more of the following component B relative to the total mass of the fiber, the fiber containing component A and component B therein, and component B being water-insoluble at a solidification point of 30°C or higher. Component A: Aliphatic polyester Component B: one or more compounds selected from the following (1) to (3): (1) One or more compounds selected from fatty acids having 14 to 24 carbon atoms (2) One or more compounds selected from fatty acid ester compounds in which a polyhydric alcohol and two or more fatty acids are bonded, the total number of carbon atoms in all fatty acid groups being 24 or more, and the ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) being 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms. Effect of the Invention

[0006] The fiber of the present invention has enhanced hydrophobicity, and the hydrophobic treatment effect is likely to last for a long time even in water. [Brief description of the drawings]

[0007] [Figure 1]FIG. 1 is a cross-sectional perspective view showing a schematic diagram of one embodiment of a fiber according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The fiber of the present invention will now be described. The fiber of the present invention preferably contains, as its constituent components, 50 mass% or more of an aliphatic polyester (hereinafter referred to as component A) and 10 mass% or more of one or more compounds selected from the following (1) to (3) (hereinafter referred to as component B). The above content ratios of components A and B refer to the ratios when the total mass of the fiber of the present invention is taken as 100 mass%. (1) One or more compounds selected from fatty acids having 14 to 24 carbon atoms (2) One or more compounds selected from fatty acid ester compounds in which a polyhydric alcohol and two or more fatty acids are bonded, the total number of carbon atoms in all fatty acid groups being 24 or more, and the ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) being 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms. It is preferred that components A and B are contained within the interior of the fiber. Component B preferably has a solidification point of 30° C. or higher and is water-insoluble.

[0009] (Method of extracting each component) From the fiber assembly to be measured, fibers are taken out so that the mass is about 1 g. If the fiber assembly is a nonwoven fabric, a piece of the above mass is cut out. The constituent components are extracted from the taken fiber or piece using various solvents, and each constituent component is isolated by HPLC (high performance liquid chromatography).

[0010] (Method of measuring freezing point) The "solidification point" is also called the solidification temperature, and refers to the peak temperature of the exothermic peak that first appears when a sample is heated and melted in differential scanning calorimetry (DSC), then cooled at 5°C / min. This measurement is specifically performed as follows. The components extracted by the above (method of extracting each component) are sealed in an aluminum sample pan and heated at 5°C / min. After reaching 200°C by heating, the temperature is lowered at 5°C / min within 600 seconds. Then, the measurement is terminated when the temperature reaches 0°C. The peak temperature means the temperature at which the heated component starts to solidify by lowering the temperature from the molten state. The "molten state" means a state in which the component flows when an external force is applied, for example, a state in which the target component is heated to a temperature equal to or higher than its melting point. The "solidification" means crystallization, or glass transition when crystallization is not observed.

[0011] (Method for measuring the content ratio of component A and component B) The components extracted by the above (method of extracting each component) are dissolved in a deuterated solvent in which each component is soluble, and each component is identified using proton NMR. This identifies the components corresponding to components A and B. Next, the identified component A or B is extracted from the fiber assembly with a solvent capable of dissolving that component, and the content ratio of that component is determined. For example, a fiber assembly is immersed in an organic solvent capable of dissolving component B for 24 hours to extract component B. The fiber is removed from the organic solvent and dried at 40°C under reduced pressure at -0.04 MPa for 24 hours. The mass percentage of component B can then be measured by measuring the mass of the fiber after drying. Component B content (mass%) = 100 - (fiber mass after drying under reduced pressure / initial fiber mass) x 100

[0012] (Method of measuring whether components A and B are present inside a fiber) The fibers to be measured are measured for each of the constituents identified in the above (Method of measuring the content ratio of components A and B) using a time-of-flight secondary ion mass spectrometry (TOF-SIMS). When performing the measurement, the fiber is cut in a direction perpendicular to the longitudinal direction, and a cross section is analyzed to determine whether components A and B are present inside the fiber.

[0013] Component A is preferably contained in an amount of 50% by mass or more based on the total mass of the fiber, and serves as the main base material of the fiber of the present invention. By using an aliphatic polyester having a plurality of polar ester bonds as the main base material, the fiber of the present invention has high affinity with the living body. In addition, the fiber of the present invention can be made into an ultrafine fiber, which is useful, for example, as a cosmetic material.

[0014] In order to further enhance the above-mentioned effects, the content of Component A relative to the total mass of the fibers is preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 75% by mass or more. Furthermore, from the viewpoint of easily expressing hydrophobicity, the content of Component A relative to the mass of the entire fiber is preferably 90 mass% or less, more preferably 87 mass% or less, and even more preferably 85 mass% or less.

[0015] Component B is preferably contained as an additive in the fiber of the present invention in an amount of 10% by mass or more based on the mass of the entire fiber, thereby enhancing the hydrophobicity of the fiber of the present invention. Component B preferably contains one or more compounds selected from the above (1) to (3), and the compounds each have a carbon number as specified in the above, which contributes to the hydrophobicity. From the viewpoint of enhancing the hydrophobicity, the fatty acid ester compound of (2) preferably contains one or more compounds selected from diesters or higher than monoesters, and preferably contains a compound in which the ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) is at least 1. The number of fatty acid groups and the number of hydroxyl groups in Component B are calculated based on the molecular structure identified by the above (Method for measuring the content ratio of Components A and B). In addition, the compound contained in component B preferably contains a fatty acid structural portion as shown in (1) to (3) above. This gives the compound a basic structural similarity to the aliphatic polyester of component A. Therefore, component B has high compatibility with component A, and component B is unlikely to separate from component A in the fiber of the present invention. Furthermore, in the production method described below, component B is well dispersed in component A, enabling stable spinning. This is technically significant for the production of ultrafine fibers. From this viewpoint, the fatty acid ester (2) preferably contains a compound having no repeating units in the fatty acid group. Furthermore, component B is hypoallergenic to the skin and is useful, for example, as a cosmetic material.

[0016] The "fatty acid group" in the fatty acid ester compound (2) above means a chemical structural portion derived from a fatty acid. Specifically, the "fatty acid group" means a structure containing a hydrocarbon group of a fatty acid and a carbonyl group bonded to the hydrocarbon group in a structure in which a polyhydric alcohol and a fatty acid are ester-bonded. The "carbon number of all fatty acid groups" means the total number of carbon atoms in all "structures containing a hydrocarbon group of a fatty acid and a carbonyl group bonded to the hydrocarbon group" that are ester-bonded. Here, when the fatty acid group has a substituent, the carbon number of the substituent is also included in the "carbon number of all fatty acid groups". Moreover, the "polyhydric alcohol portion" in the fatty acid ester compound of (2) above means a chemical structure portion derived from a polyhydric alcohol, excluding the "fatty acid group" above.

[0017] Component B is preferably water-insoluble. The term "water-insoluble" used herein means that the proportion of water-insoluble components measured by the following method is 95% by mass or more. Component B preferably has a carbon chain structure with the number of carbon atoms specified in each of (1) to (3) above, and in the fatty acid ester of (2) above, the polyhydric alcohol moiety is preferably esterified with the fatty acid group, which contributes to the water insolubility. It is also preferable that the solidification point of component B is 30° C. or higher. This allows component B to exist in a solid state at room temperature (23° C.) and to be less likely to dissolve in water (less likely to separate from the main base).

[0018] (Method for measuring water insolubility of component B) Extract the components using the above (method of extracting each component), and identify component B using the above (method of measuring the content ratio of components A and B). In an environmental area with a temperature of 23°C and a relative humidity (RH) of 50%, add 50 mL of deionized water to a 100 mL beaker. Add 0.5 g of component B in the form of particles with a diameter of 1 mm or less to the deionized water and leave it to stand for 24 hours. Then, in order to extract component B, perform vacuum filtration using filter paper. At that time, use filter paper with a retention particle size of 5 μm (Qualitative filter paper No. 2 manufactured by ADVANTEC). Before performing vacuum filtration, measure the mass of the filter paper. After performing vacuum filtration, the filter paper and component B are dried under reduced pressure for 24 hours. Specifically, the temperature of this vacuum drying is 40°C and the vacuum level is -0.04 MPa. The mass of the filter paper after drying under reduced pressure and the mass of component B on the filter paper are measured, and the mass of the filter paper before filtration under reduced pressure is subtracted to calculate the mass of component B that was insoluble in water. The mass change (%), that is, the proportion of water-insoluble components in component B, is calculated using the following formula (1). (Ratio of water-insoluble components) = ((Mass of filter paper and component B after drying under reduced pressure - Mass of filter paper before filtration under reduced pressure) / Mass of component B at the time of weighing) x 100 (1)

[0019] In order to further enhance the above-mentioned effect, the content of Component B relative to the total mass of the fibers is preferably 11 mass% or more, more preferably 15 mass% or more, and even more preferably 18 mass% or more. The content of Component B in the total mass of the fiber is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. By keeping the content below the upper limit, the strength of the fiber can be maintained.

[0020] From the viewpoint of improving the above-mentioned effects, the solidification point of the compound contained in Component B is preferably 40° C. or higher, more preferably 50° C. or higher, and even more preferably 70° C. or higher. Moreover, from the viewpoint of improving storage stability, the solidification point of the compound contained in Component B is preferably 100° C. or lower, more preferably 90° C. or lower, and even more preferably 80° C. or lower.

[0021] In component B, the number of carbon atoms of the compound contained in (1) is preferably 14 or more and 24 or less, from the viewpoint of further increasing the water insolubility and hydrophobicity described above.

[0022] In component B, the number of carbon atoms of the compounds contained in (2) and (3) is preferably 24 or more and 36 or less, from the viewpoint of further increasing the water insolubility and hydrophobicity described above.

[0023] By containing component A and component B in the above-mentioned ratio in the fiber of the present invention, even if the fiber of the present invention comes into contact with water or is in water, dissolution of component B in water is unlikely to occur, and the enhanced hydrophobicity is likely to be maintained. As a result, the fiber of the present invention has water resistance and the hydrophobic treatment effect is likely to last for a long time even in water. The fibers of the present invention can be used, for example, by impregnating them with various hydrophobic liquids or dispersing them in hydrophobic liquids. The fibers of the present invention and nonwoven fabrics containing the fibers can be included as components of various textile products. Examples of such textile products include skin care sheets in the cosmetic field.

[0024] The fiber of the present invention, which has the above-mentioned enhanced hydrophobicity, preferably has a fiber wet tension test value shown below of 32 mN / m or more and 59 mN / m or less, more preferably 37 mN / m or less.

[0025] (Test method for wet tension of fibers) First, the fiber to be measured is used to measure the basis weight of 20 g / m 2A nonwoven fabric of 30 mm x 30 mm is prepared. In an environmental area with an ambient temperature of 23°C, the prepared nonwoven fabric is stretched horizontally in the air, and 0.02 mL of the wetting tension test liquid is dropped onto the upper surface of the nonwoven fabric using a dropper. After 2 seconds have passed since the dropping of the test liquid, the state of the test liquid on the upper surface of the nonwoven fabric to which the test liquid was dropped is visually observed. If the test liquid is found to have permeated the nonwoven fabric in the thickness direction or diffused in the surface direction, the test liquid is changed to one with a larger surface tension and the same operation is performed. If the test liquid is unable to permeate the nonwoven fabric and the droplets remain on the upper surface of the nonwoven fabric, or if the test liquid is not diffused in the surface direction and almost no wetting is observed on the upper surface, the surface tension of the test liquid used in the dropping operation immediately before such a case, i.e., the surface tension of the test liquid that has permeated or diffused into the nonwoven fabric and has the largest surface tension, is taken as the wetting tension of the nonwoven fabric at an ambient temperature of 20°C. The wetting tension test liquid used is "Wetting Tension Test Mixture" (product name) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. This is a mixed liquid of ethylene glycol monoethyl ether, formamide, methanol and water prepared according to JIS K 6768:1999.

[0026] The fiber of the present invention, which has the above-mentioned enhanced hydrophobicity, preferably has a "water contact angle measured by forming the compound contained in component B into a plate" of 92° or more and 108° or less, as shown below.

[0027] (Method for measuring the contact angle of the compound contained in component B) First, the compound contained in component B is thermally melted and molded into a plate. The size of the molded plate is 5 cm x 5 cm, and the thickness is 1 mm. The contact angle of the molded plate is measured using the sessile drop method. Specifically, the measurement device used is an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. The droplets are used as the drop liquid. In an environmental region with a temperature of 25 degrees and a relative humidity (RH) of 65%, the amount of liquid discharged from the inkjet type water droplet discharge part (CTC-25 pulse injector with a discharge part hole diameter of 25 μm manufactured by Cluster Technology Co., Ltd.) is set to 1 μm, and the droplets are dropped directly onto the molding plate. The dropping state is recorded by a high-speed recording device connected to a camera installed horizontally. From the viewpoint of later image analysis and image analysis, it is preferable that the recording device is a personal computer with a high-speed capture device. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of a water droplet landing on the fiber removed from the nonwoven fabric is analyzed using the attached software FAMAS (software version 2.6.2, analysis method is droplet method, analysis method is θ / 2 method, image processing algorithm is non-reflective, image processing image mode is frame, threshold level is 200, curvature correction is not performed), and the angle between the surface of the water droplet in contact with the air and the forming plate is calculated, which is taken as the contact angle.

[0028] In the fiber of the present invention, various aliphatic polyesters can be used as the aliphatic polyester contained in Component A. For example, it is preferable that the component A contains one or more selected from polyethylene terephthalate, polylactic acid, polycaprolactone (hereinafter also referred to as PCL), polybutylene succinate (hereinafter also referred to as PBS), polybutylene succinate adipate (hereinafter also referred to as PBSA), and polydioxanone (hereinafter also referred to as PDO). Among them, it is more preferable that the fiber contains a biodegradable compound. This can reduce the impact on the environment when the fiber of the present invention is released into the environment (for example, when a nonwoven fabric made of the fiber of the present invention is used as a cosmetic material and the fiber is washed away during washing for reuse, etc.). Note that "biodegradable" here refers to a polyester whose biodegradability measured in accordance with JIS K 6953-1 is 30% or more. Specific examples of biodegradable aliphatic polyesters preferably include one or more selected from PCL, PBS, PBSA, and PDO, and among these, it is preferable to include PCL because of its high biodegradability.

[0029] In the nonwoven fabric of the present invention, various types of component B can be used which are water-insoluble at a solidification point of 30° C. or higher and have the number of carbon atoms specified by each of the above (1) to (3).

[0030] The "fatty acid having 14 to 24 carbon atoms" in (1) above preferably contains, for example, one or more selected from stearic acid, behenic acid, and myristic acid. Among these, it is more preferable to contain stearic acid and behenic acid, since they have excellent storage stability and a high melting point when combined with component A, and also have high storage stability for the fibers, and can make it easier to maintain the hydrophobic treatment effect.

[0031] The above (2) "fatty acid ester compound in which a polyhydric alcohol and two or more fatty acids are bonded, and the total number of carbon atoms in all fatty acid groups is 24 or more" preferably includes, for example, one or more selected from sorbitan fatty acid ester compounds. These preferably include a diester or more than a monoester, from the viewpoint of increasing the hydrophobicity of the fiber of the present invention. In the compound contained in the fatty acid ester compound of (2), each fatty acid group having an ester bond preferably has a skeleton in which carbon atoms are single-bonded to each other, and more preferably the skeleton is linear. Furthermore, as described above, it is preferable that the fatty acid group does not have a repeating unit.

[0032] The sorbitan fatty acid ester compound preferably contains, for example, one or more compounds selected from sorbitan distearate and sorbitan oleate.

[0033] The "sphingolipid having 24 or more carbon atoms" in (3) above preferably includes, for example, one or more selected from sphingoglycolipids and sphingophospholipids. From the viewpoint of obtaining fibers having a sufficiently low wet tension, it is preferable that component B contains one or more selected from (1) among (1) to (3). From the viewpoints of sustaining the hydrophobicity in water and obtaining stability of the hydrophobicity in water due to the high water-insolubility of Component B alone, it is more preferable that Component B contains one or more selected from stearic acid and behenic acid among the above (1).

[0034] In such a fiber of the present invention, from the viewpoint of further enhancing the above-mentioned hydrophobicity and making it more difficult to wet, it is preferable that component A constitutes the core layer of the fiber and extends in the longitudinal direction of the fiber (fiber length direction), and a part of component B is arranged on the fiber surface (i.e., the surface of the core layer of component A). In this case, component B is present inside the fiber, but a part of it is exposed on the fiber surface side. In addition, some of the component B present inside the fiber may be mixed with the thermoplastic resin of component A. From the same viewpoint, it is preferable that the peripheral surface of the core layer 2 of component A is covered with a part of component B as a skin layer 3, as in the constituent fiber 1 shown in FIG. 1. In this case, the interface of component concentrations between the skin layer 3 of component B and the core layer 2 of component A does not need to be clear, and it is preferable that it is blurred. Furthermore, the skin layer 3 of component B may cover the entire fiber surface, or may cover only a part of it. When it is partially covered, it may be arranged in a sea-island structure including a region with the skin layer 3 of component B including a region without the skin layer 3 of component B, or it may be arranged such that the region with the skin layer 3 of component B and the region without the skin layer 3 of component B are separated.

[0035] In the fiber of the present invention, by containing the above-mentioned components A and B in specific content ratios, thinner fibers can be obtained by the production method described below, and the uniformity of the fiber diameter can also be improved. Therefore, the nonwoven fabric produced using the fiber of the present invention preferably has an average fiber diameter of 0.1 μm or more and 5.0 μm or less. The nonwoven fabric containing such ultrafine fibers as constituent fibers has a fine grain and a soft feel. In addition, the capillary force is higher. When this nonwoven fabric is impregnated with various hydrophobic solutions to be used as cosmetic materials, it places less strain on the skin, improves the sustained release of the hydrophobic solutions when they are supplied to the skin, and allows the effects of the solutions to last longer. In addition, since the hydrophobic treatment effect tends to last for a long time, the products can be washed after use and used repeatedly. In this case, if component A contains a biodegradable compound, even if some of the fibers are washed away during the washing, the burden on the environment is reduced.

[0036] From the above viewpoints, the average fiber diameter of the nonwoven fabric produced using the fibers of the present invention is more preferably 4 μm or less, and even more preferably 2.5 μm or less. From the viewpoint of improving the strength of the fibers, the average fiber diameter is more preferably 0.2 μm or more, and further preferably 0.5 μm or more.

[0037] (Method of measuring average fiber diameter) From the two-dimensional image obtained by scanning electron microscope observation, 200 fibers are randomly selected, excluding defects such as fiber clumps, intersections of constituent fibers, and polymer droplets, and the width perpendicular to the longitudinal direction (fiber length direction) of each fiber (the length when a line is drawn through the center of the fiber in a cross section perpendicular to the longitudinal direction of the constituent fibers) is measured. The sum of these values ​​is divided by the number of fibers measured to obtain the average fiber diameter of the nonwoven fabric being measured. Note that if the cross section perpendicular to the longitudinal direction of the fiber is not circular, the above average fiber diameter is converted to a circle equivalent diameter.

[0038] Next, a preferred embodiment of the method for producing a fiber of the present invention will be described. The method for producing fibers of this embodiment preferably uses a thermoplastic resin composition containing 50% by mass or more of component A and 10% by mass or more of component B. As described above, component A used here is an aliphatic polyester. As described above, component B is one or more selected from the above (1) to (3), and is a water-insoluble compound with a solidification point of 30° C. or higher. It is preferable that the thermoplastic resin composition (component A+component B) is subjected to a step (I) of heating and melting it, and a step (II) of discharging it from a nozzle.

[0039] In the step (I), for example, components A and B are fed through a hopper into a housing connected to the hopper. In the housing, components A and B are heated and melted to prepare a molten liquid of the thermoplastic resin composition (hereinafter, also simply referred to as a resin mixture molten liquid). This resin mixture molten liquid is extruded toward a discharge nozzle by the rotation of a screw or by pressure such as air, and is supplied to the discharge port at the tip of the nozzle. In this case, the nozzle may be one or more. Next, in the above-mentioned step (II), the supplied resin mixture molten liquid is discharged from the nozzle and spun. The discharged resin mixture molten liquid is stretched, cooled, and solidified as it moves away from the discharge port at the tip of the nozzle, and becomes a fiber. At this time, the above-mentioned ultrafine fibers can be spun by appropriately setting the hole diameter of the discharge port at the tip of the nozzle. This makes it possible to manufacture a nonwoven fabric preferably having an average fiber diameter of 5 μm or less. In this step, when components A and B having different solidification points are spun, the component with the higher solidification point solidifies earlier during spinning, and is therefore stable. Since a stable state is formed as the interface between the air and the molten resin, the part that is easily solidified is formed on the air side, and the above-mentioned core layer 2 and skin layer 3 are easily formed due to the difference in solidification point.

[0040] In the step (II), the extrusion rate of the molten thermoplastic resin composition from the nozzle is preferably 0.1 g / min·nozzle or more, more preferably 0.2 g / min·nozzle or more, and even more preferably 0.5 g / min·nozzle or more. The extrusion speed of the molten thermoplastic resin composition from the nozzle is preferably 10 g / min / nozzle or less, more preferably 5 g / min / nozzle or less, and even more preferably 2 g / min / nozzle or less.

[0041] The viscosity of the resin mixture molten liquid when discharged from the nozzle is preferably 1 Pa·s or more, more preferably 2 Pa·s or more, and even more preferably 5 Pa·s or more, from the viewpoint of preventing fiber breakage during spinning. The viscosity of the resin mixture molten liquid when discharged from the nozzle is preferably 20 Pa·s or less, more preferably 15 Pa·s or less, and even more preferably 10 Pa·s or less, from the viewpoint of lowering the viscosity and facilitating thinning of the fibers.

[0042] (Method for measuring viscosity of resin mixture melt) The melt viscosity is measured using a rotational rheometer. Specifically, the measurement is performed using an Anton Paar MCR305 device. A parallel plate with a diameter of 50 mm is used as the measurement jig, and the shear rate is 0.1 s -1 The viscosity is measured at 100°C. The temperature during measurement is set to match the spinning conditions. The sample is set on the plate, and after the resin has melted, the clearance is set to 1 mm and any part protruding from the Φ50 mm parallel plate is trimmed. After that, the sample is waited until it reaches the measurement temperature, and then the measurement is started. The viscosity value is obtained 100 seconds after rotation has started and used as the measured value.

[0043] In the fiber manufacturing method of this embodiment, it is preferable to perform a spraying process of a heated fluid in the step (II). This spraying is performed on the resin mixture molten liquid discharged from the nozzle in a state before it is completely solidified. The heat of the sprayed heated fluid can more actively stretch the discharged resin mixture molten liquid, and even finer fibers can be formed. The heated fluid can be sprayed along the discharge direction of the resin mixture molten liquid or in a direction intersecting the discharge direction.

[0044] The temperature of the heating fluid is preferably higher than the solidification point of component A in order to make the above-mentioned stretching more effective. Specifically, the difference between the temperature of the heating fluid and the solidification point of component A is preferably 30° C. or more, more preferably 40° C. or more, and even more preferably 50° C. or more. Moreover, the difference between the temperature of the heated fluid and the solidification point of component A is preferably 150° C. or less, more preferably 140° C. or less, and even more preferably 130° C. or less, from the viewpoint of suppressing decomposition of the resin.

[0045] In the fiber manufacturing method of the present embodiment, it is preferable to carry out an electrostatic spinning process in the step (II). This electrostatic spinning process may be carried out together with the above-mentioned heated fluid spraying process, or may be carried out instead of the heated fluid spraying process. The electrostatic spinning process is also called the electric field spinning method (electrospinning method), and is a process in which the nozzle from which the resin is discharged is directly or indirectly charged to impart an electric charge to the resin and spin it. This allows for more active stretching, and allows for even finer fibers to be formed. For example, a charged electrode and a high voltage generator connected to the charged electrode are disposed at a position corresponding to the nozzle and spaced apart from it. With this configuration, a high voltage can be applied between the nozzle tip and the charged electrode to form an electric field between them, and the resin mixture molten liquid discharged from the nozzle tip can be charged. It is preferable that the charged electrode is made of a conductive material such as a metal, or is covered with a dielectric.

[0046] In the method for producing a fiber according to the present embodiment, in addition to component A and component B, other agents may be further contained as long as the effects of the present invention are not impaired. For example, from the viewpoint of increasing the amount of charge, charge control agents, lubricants, antistatic agents, surfactants, plasticizers, etc. may be mentioned. In addition to these, antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, etc. may also be contained.

[0047] In this way, the fibers obtained by the fiber manufacturing method of this embodiment are collected and formed into a sheet, and a nonwoven fabric can be suitably manufactured. For example, the resin mixture molten liquid discharged from the nozzle tip is collected in a collecting section while being cooled and stretched, and is deposited in a sheet to form a nonwoven fabric. From the viewpoint of improving the collecting ability, the collecting section preferably includes a collecting electrode and a high voltage generator connected to the collecting electrode. The collecting electrode and the high voltage generator in the collecting section may also serve as the charging electrode and the high voltage generator described above, or may be provided separately. In the method for producing the nonwoven fabric of this embodiment, as described above, ultrafine fibers can be produced uniformly, efficiently, and at high speed from the resin mixture molten liquid of Component A and Component B, so that the nonwoven fabric of the present invention having a larger area can be produced industrially and efficiently on an actual production line.

[0048] In relation to the above-mentioned embodiments, the present invention further discloses the following fibers, nonwoven fabrics, and textile products.

[0049] <1> The fiber contains 50% by mass or more of the following component A and 10% by mass or more of the following component B relative to the total mass of the fiber, and contains the components A and B inside the fiber, The component B is a fiber that is insoluble in water at a solidification point of 30° C. or higher. Component A: Aliphatic polyester Component B: one or more compounds selected from the following (1) to (3): (1) One or more compounds selected from fatty acids having 14 to 24 carbon atoms (2) One or more compounds selected from fatty acid ester compounds in which a polyhydric alcohol and two or more fatty acids are bonded, the total number of carbon atoms in all fatty acid groups being 24 or more, and the ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) being 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms.

[0050] <2> A part of the component B is disposed on the fiber surface. <1> The fiber described in <3> The component includes a compound having a water contact angle of 92° or more when measured in a plate form. <1> or <2> The fiber described in <4> The wet tension test value of the fiber is 32 mN / m or more and 59 mN / m or less. <1> ~ <3> 2. The fiber according to any one of claims 1 to 11. <5> The component A includes a compound that is biodegradable. <1> ~ <4> 2. The fiber according to any one of claims 1 to 11. <6> The biodegradability means that the biodegradability of the polyester measured in accordance with JIS K 6953-1 is 30% or more. <5> The fiber described in <7> Component A includes one or more selected from polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polydioxanone. <1> ~ <6> 2. The fiber according to any one of claims 1 to 11. <8> The component A includes polycaprolactone. <1> ~ <7> 2. The fiber according to any one of claims 1 to 11. <9> The content of the component A is 55% by mass or more and 90% by mass or less, preferably 60% by mass or more and 87% by mass or less, and more preferably 75% by mass or more and 85% by mass or less, based on the total mass of the fiber. <1> ~ <8> 2. The fiber according to any one of claims 1 to 11. <10> The component B includes a compound having a solidification point of 40° C. or more and 100° C. or less, preferably 50° C. or more and 90° C. or less, more preferably 70° C. or more and 80° C. or less. <1> ~ <9> 2. The fiber according to any one of claims 1 to 11. <11> The compounds (2) and (3) include compounds having 24 to 36 carbon atoms. <1> ~ <10> 2. The fiber according to any one of claims 1 to 11. <12> The wet tension test value of the fiber is 32 mN / m or more and 37 mN / m or less. <1> ~ <11> 2. The fiber according to any one of claims 1 to 11. <13> The component B includes a compound having a water contact angle of 92° or more and 108° or less when measured in a plate form. <1> ~ <12> 2. The fiber according to any one of claims 1 to 11. <14> The compound (1) includes one or more selected from stearic acid, behenic acid, and myristic acid. <1> ~ <13> 2. The fiber according to any one of claims 1 to 11. <15> The compound (2) includes one or more selected from sorbitan fatty acid ester compounds. <1> ~ <14> 2. The fiber according to any one of claims 1 to 11. <16> In the compound (2), The sorbitan fatty acid ester compound includes one or more selected from sorbitan distearate and sorbitan oleate, Preferably, one or more of the above is sorbitan distearate. The above <15> The fiber described in <17> The compound (2) includes one or more compounds selected from diesters or higher. <1> ~ <16> 2. The fiber according to any one of claims 1 to 11. <18> The compound (2) includes a compound having no repeating unit in the fatty acid group. <1> ~ <17> 2. The fiber according to any one of claims 1 to 11. <19> The compound (2) has a skeleton in which each fatty acid group linked by an ester bond has carbon atoms bonded to each other by a single bond, and preferably the skeleton is linear. <1> ~ <18> 2. The fiber according to any one of claims 1 to 11. <20> The compound (3) includes one or more selected from sphingoglycolipids and sphingophospholipids. <1> ~ <19> 2. The fiber according to any one of claims 1 to 11. <21> The component B includes one or more compounds selected from the compound (1) among the compounds (1) to (3), and the compound (1) includes one or more compounds selected from stearic acid and behenic acid. <1> ~ <20> 2. The fiber according to any one of claims 1 to 11.

[0051] <22> The above <1> ~ <21> A nonwoven fabric comprising the fiber according to any one of claims 1 to 5. <23> The nonwoven fabric has an average fiber diameter of 0.1 μm or more and 5 μm or less. <22> The nonwoven fabric described in <24> The nonwoven fabric has an average fiber diameter of 0.5 μm or more and 2.5 μm or less. <23> The nonwoven fabric described in <25> The above <1> ~ <21> The fiber according to any one of the above, <22> ~ <24> A textile product comprising the nonwoven fabric according to any one of claims 1 to 5. <26> The textile product is a skin care sheet. <25> A textile product according to claim 1. EXAMPLES

[0052] The present invention will be described in more detail below based on examples, but the present invention is not limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified. "←" means that the contents are the same as those in the left column.

[0053] (Examples 1 to 3) A thermoplastic resin composition was prepared by mixing PCL as component A and behenic acid as component B in the ratio shown in Table 1. A melt of the thermoplastic resin composition was prepared, and the fiber samples of Examples 1 to 3 were prepared by melt electrospinning using one nozzle. In addition, the fibers were deposited simultaneously with spinning to prepare nonwoven fabric samples of Examples 1 to 3 (basis weight 5 g / m 2 ) was prepared. The average fiber diameter of the nonwoven fabric sample was 2 μm. In the melt electrospinning method, the applied voltage was −10 kV. The molten thermoplastic resin composition discharged from the nozzle was stretched by spraying a heated fluid at 180° C. The fiber samples of Examples 1 and 2 had a structure in which a skin layer of component B covered a core layer of component A, as shown in FIG. 1.

[0054] (Examples 4 to 6) Fiber samples and nonwoven fabric samples of Examples 4 to 6 were prepared in the same manner as in Example 1, except that component B was changed to the one shown in Table 1.

[0055] Comparative Example 1 A fiber sample and a nonwoven fabric sample of Comparative Example 1 were prepared in the same manner as in Example 1, except that component B was not used.

[0056] Comparative Example 2 A fiber sample and a nonwoven fabric sample of Comparative Example 2 were prepared in the same manner as in Example 1, except that the content of component B was 5 mass %. In the fiber sample of Comparative Example 2, a structure in which component B was arranged on the fiber surface was not observed.

[0057] Comparative Example 3 An attempt was made to prepare a fiber sample and a nonwoven fabric sample for Comparative Example 3 in the same manner as in Example 1, except that a compound having 10 carbon atoms (less than 14) was used instead of component B. However, smoke was generated during the spinning process, and therefore a fiber sample and a nonwoven fabric sample could not be obtained. Comparative Example 4 Fiber samples and nonwoven fabric samples were prepared in the same manner as in Example 1, using only the compounds in Table 1 instead of component A. That is, fiber samples and nonwoven fabric samples were prepared without component B, similar to Comparative Example 1. Next, component B was added to the fiber samples and nonwoven fabric samples in a liquid form shown in Table 1, and the samples were immersed to prepare fiber samples and nonwoven fabric samples of Comparative Example 4.

[0058] For each of the above-mentioned Examples and Comparative Examples, the wetting tension and the contact angle of component B were measured. These were measured based on the above-mentioned (Test method for wetting tension of fiber) and (Method for measuring contact angle of component B). In addition, the durability of the hydrophobic treatment effect (enhanced hydrophobicity) in water was confirmed according to the following (Method for confirming durability of hydrophobicity properties in fiber). The measurements were based on the following: (Method for confirming the durability of hydrophobic properties in fibers) In an environmental area with a temperature of 23°C and a relative humidity (RH) of 50%, 50mL of deionized water was placed in a 100mL beaker, 0.5g of fiber was taken out, and left to stand in the deionized water for 24 hours. After that, the fiber was taken out, sandwiched between filter paper, and loaded with a 2kg weight for 10 minutes to remove sufficient deionized water. In order to further remove the deionized water from the fiber, drying was performed under reduced pressure. Specifically, the fiber was dried at a temperature of 40°C and a pressure of -0.04MPa for 24 hours. After that, a wetting tension test was performed on the fiber in the same manner as described above (Wetting tension test method for fiber) to confirm whether the value was the same as before storage in deionized water. If the change value was 0, it was determined that the hydrophobic properties were maintained. (Change in value) = (Wetting test liquid value before underwater storage) - (Wetting test liquid value after underwater storage)

[0059] [Table 1]

[0060] As shown in Table 1, in comparison with Comparative Examples 1 and 2, which did not contain Component B or contained 5% Component B, it was confirmed that in Examples 1 to 6, the wetting tension of the fiber after spinning was 59 mN / m or less, and the hydrophobicity in water was maintained. In addition, compared with Comparative Example 3, which used a compound with a smaller carbon number instead of Component B, Examples 1 to 6 were able to successfully obtain fiber samples. In comparison with Comparative Example 4, which used polypropylene instead of Component A and added Component B later, Examples 1 to 5 also showed no change in the durability of properties in water from before immersion in water. [Explanation of symbols]

[0061] 1. Fiber 2. Core layer of component A 3. Epidermal layer of component B

Claims

1. The fiber contains 50% by mass or more of the following component A and 10% by mass or more of the following component B relative to the mass of the entire fiber, and the fiber contains the components A and B inside, The component B is a fiber that is insoluble in water at a solidification point of 30°C or higher. Component A: Aliphatic polyester Component B: one or more compounds selected from the following (1) to (3): (1) One or more compounds selected from fatty acids having 14 to 24 carbon atoms (2) One or more compounds selected from fatty acid ester compounds in which a polyhydric alcohol and two or more fatty acids are bonded, the total number of carbon atoms in all fatty acid groups being 24 or more, and the ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) being 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms

2. The fiber according to claim 1 , wherein a portion of component B is disposed on the surface of the fiber.

3. 2. The fiber according to claim 1, wherein the component comprises a compound having a water contact angle of 92° or more when measured in a plate form.

4. The fiber according to claim 1, wherein the fiber has a wet tension test value of 32 mN / m or more and 59 mN / m or less.

5. The fiber of claim 1 , wherein component A comprises a compound that is biodegradable.

6. The fiber of claim 1 , wherein component A comprises polycaprolactone.

7. A nonwoven fabric comprising the fiber according to any one of claims 1 to 6.

8. 8. The nonwoven fabric according to claim 7, wherein the average fiber diameter of the nonwoven fabric is 0.1 μm or more and 5 μm or less.

9. A textile product comprising the fiber according to any one of claims 1 to 6.

10. A textile product comprising the nonwoven fabric of claim 7.