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 Art

[0002] Fibers are used in various scenarios such as filters, sanitary materials, cosmetic materials, and medical materials (for example, Patent Documents 1 to 3). Fibers may be used by impregnating them with an active ingredient as a liquid. With the development of spinning technology, many studies have been conducted to produce various fibers such as ultrafine fibers (for example, fiber diameter of 50 μm or less) using thermoplastic resins. However, the surface physical properties of such fibers are easily influenced by the hydrophobicity of the thermoplastic resin used. Therefore, for example, when impregnating a more hydrophobic liquid into the fibers quickly for use in cosmetic materials or quickly dispersing the crushed fibers in a more hydrophobic liquid for use as a filler in a thin film, the applications of the prepared fibers are limited when using the hydrophobicity of the thermoplastic resin material itself as it is.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the above-mentioned fibers are used in vivo or on the skin, aliphatic polyester is sometimes preferred as the specific material for the fibers. Fibers made of aliphatic polyester may have insufficient surface hydrophobicity in terms of affinity to more hydrophobic liquids. Conventionally, it was common to apply a hydrophobic agent to further enhance the hydrophobicity of the fiber surface. However, since this hydrophobicity is achieved by coating or impregnation, when the fiber is in water, the hydrophobic agent detaches from the surface, inevitably reducing the hydrophobic treatment effect, and there was room for improvement. In view of the above points, the present invention relates to a fiber that has enhanced hydrophobicity and whose hydrophobic treatment effect is easily maintained for a long time even in water. [Means for solving the problem]

[0005] The present invention provides a fiber that contains 50% by mass or more of component A and 10% by mass or more of component B, with respect to the total mass of the fiber, wherein component A and component B are contained within the fiber, and component B has a solidification point of 30°C or higher and is water-insoluble. Component A: Aliphatic polyester Component B: One or more compounds selected from (1) to (3) below. (1) One or more compounds selected from fatty acids with 14 to 24 carbon atoms. (2) One or more fatty acid ester compounds selected from fatty acid ester compounds in which a polyhydric alcohol is bonded to two or more fatty acids, the sum of the number of carbon atoms of all fatty acid groups is 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) is 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms. [Effects of the Invention]

[0006] The fibers of the present invention have enhanced hydrophobicity, making it easier for the hydrophobic treatment effect to last longer even in water. [Brief explanation of the drawing]

[0007] [Figure 1]This is a schematic cross-sectional perspective view showing one embodiment of the fiber according to the present invention. [Modes for carrying out the invention]

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

[0009] (Extraction method for each component) Fibers are extracted from the fiber aggregate to be measured so that their mass is approximately 1 g. If the fiber aggregate is a nonwoven fabric, a section of the above mass is cut out. Components are extracted from the extracted fibers or section using various solvents, and each component is isolated by HPLC (high-performance liquid chromatography).

[0010] (Method for measuring the solidification point) The aforementioned "solidification point," also called the solidification temperature, refers to the peak temperature of the exothermic peak that first appears when the sample is heated by differential scanning calorimetry (DSC) and then cooled at 5°C / min after melting. Specifically, this measurement is performed as follows: The components extracted by the above (extraction method for each component) are sealed in an aluminum sample pan and heated, increasing the temperature at 5°C / min. After reaching 200°C, the temperature is decreased at 5°C / min within 600 seconds. Then, the measurement is terminated when the temperature reaches 0°C. The peak temperature mentioned above refers to the temperature at which the heated component begins to solidify upon cooling from a molten state. The "molten state" refers to the state in which the component flows when an external force is applied, for example, a state in which the component is heated above its melting point. The "solidification" refers to crystallization, or, if crystallization is not observed, glass transition.

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

[0012] (Method for measuring the presence of components A and B inside a fiber) For each constituent identified by the above (method for measuring the content ratios of component A and component B), the fiber to be measured is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS). When performing the measurement, by analyzing a cross-section obtained by cutting the fiber in a direction perpendicular to the longitudinal direction, it is determined whether component A and component B are contained inside the fiber.

[0013] Component A is preferably contained at 50% by mass or more based on the mass of the entire fiber and serves as the main base of the fiber of the present invention. By using an aliphatic polyester having a plurality of polar ester bonds as the main base, the fiber of the present invention has enhanced affinity with the living body. Further, the fiber of the present invention can be made into ultrafine fibers and is significant as, for example, a cosmetic material.

[0014] From the viewpoint of further enhancing the above-described action, the content ratio of component A based on the mass of the entire fiber is preferably 55% by mass or more, more preferably 60% by mass or more, and still more preferably 75% by mass or more. Also, from the viewpoint of facilitating the expression of hydrophobicity, the content ratio of component A based on the mass of the entire fiber is preferably 90% by mass or less, more preferably 87% by mass or less, and still more preferably 85% by mass or less.

[0015] <00,00096>Component B is preferably contained at 10% by mass or more based on the mass of the entire fiber as an additive in the fiber of the present invention. Thereby, the hydrophobicity of the fiber of the present invention is enhanced. Component B preferably contains one or more compounds selected from the above (1) to (3), and the carbon number defined by each of the compounds contributes to the hydrophobicity. From the viewpoint of enhancing the hydrophobicity, the fatty acid ester compound of the above (2) preferably contains one or more compounds selected from diesters or higher rather than monoesters, and preferably contains a compound having a ratio of the number of fatty acid groups to the number of hydroxyl groups (number of fatty acid groups / number of hydroxyl groups) of 1 or more. 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 ratios of component A and component B). In addition, the compound contained in component B preferably contains a fatty acid structural portion, as described in (1) to (3) above. This gives it a basic structural similarity to the aliphatic polyester of component A. Therefore, component B has high compatibility with component A, and component B is difficult to separate from component A in the fiber of the present invention. Furthermore, in the manufacturing method described later, component B disperses well in component A, enabling stable spinning. This is technically significant for the production of ultrafine fibers. From this viewpoint, it is preferable that the fatty acid ester in (2) above includes a compound in which the fatty acid group does not have repeating units. Furthermore, component B is low-irritant to the skin and is significant as a cosmetic ingredient, for example.

[0016] In the fatty acid ester compound described in (2) above, the "fatty acid group" refers to the chemical structural portion derived from the fatty acid. Specifically, the "fatty acid group" refers to a structure in which a polyhydric alcohol and a fatty acid are esterified, and which includes the hydrocarbon group of the fatty acid and the carbonyl group bonded to the hydrocarbon group. "Total number of carbon atoms of all fatty acid groups" refers to the total number of carbon atoms in all esterified "structures including the hydrocarbon group of the fatty acid and the carbonyl group bonded to the hydrocarbon group". Here, if the fatty acid group has substituents, the number of carbon atoms of the substituents is also included in the "total number of carbon atoms of all fatty acid groups". Furthermore, the "polyhydric alcohol portion" in the fatty acid ester compound of (2) above refers to the chemical structure portion derived from the polyhydric alcohol, and is the portion excluding the "fatty acid group".

[0017] Component B is preferably water-insoluble. Here, "water-insoluble" means that the proportion of water-insoluble components, as measured by the method described below, 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 case of the fatty acid ester of (2), it is preferable that the polyhydric alcohol portion is esterified with the fatty acid group. This contributes to the water-insoluble nature. Furthermore, it is preferable that the solidification point of component B is 30°C or higher. This ensures that component B exists in a solid state at room temperature (23°C) and is not easily dissolved in water (it is not easily separated from the main base).

[0018] (Method for measuring the water-insoluble nature of component B) Extraction is performed according to the method described above (extraction method for each component), and component B is identified according to the method described above (measurement method for the content ratio of component A and component B). In an environment with a temperature of 23°C and a relative humidity (RH) of 50%, 50 mL of deionized water is placed in a 100 mL beaker. 0.5 g of component B in particulate form with a diameter of 1 mm or less is added to the deionized water and allowed to stand for 24 hours. After that, vacuum filtration is performed using filter paper to separate component B. At this time, filter paper with a particle size retention of 5 μm is used (Qualitative filter paper No. 2 manufactured by ADVANTEC). Before performing vacuum filtration, the mass of the filter paper is measured. The filter paper and component B obtained after vacuum filtration are dried under reduced pressure for 24 hours. Specifically, this vacuum drying is performed at a temperature of 40°C and a reduced pressure of -0.04 MPa. The mass of the filter paper and the mass of component B on the filter paper after vacuum drying are measured, and the mass of component B that was insoluble in water is calculated by subtracting the mass of the filter paper before vacuum filtration. The mass change (%), i.e., the proportion of the water-insoluble component B, is calculated using the following formula (1). (Percentage of non-water-soluble components) = ((Mass of filter paper and component B after vacuum drying - Mass of filter paper before vacuum filtration) / Mass of component B at weighing) × 100 (1)

[0019] From the viewpoint of further enhancing the above-mentioned effects, the content of component B relative to the total mass of the fiber is preferably 11% by mass or more, more preferably 15% by mass or more, and even more preferably 18% by mass or more. Furthermore, the content of component B relative to 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 it below the above 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. Furthermore, 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 in the compound contained in (1) is preferably 14 to 24, from the viewpoint of further enhancing the aforementioned water-insoluble and hydrophobic properties.

[0022] In component B, the number of carbon atoms in the compounds contained in (2) and (3) is preferably 24 to 36, from the viewpoint of further enhancing the aforementioned water-insoluble and hydrophobic properties.

[0023] In the fibers of the present invention, by containing components A and B in the aforementioned proportions, the dissolution of component B in water is less likely to occur even when the fibers of the present invention come into contact with water or are submerged in water, and the enhanced hydrophobicity is easily maintained. As a result, the fibers of the present invention have water resistance and the hydrophobic treatment effect tends to last longer even in water. Such fibers of the present invention can be used, for example, by impregnating them with various hydrophobic liquids or by dispersing them in hydrophobic liquids. The fibers of the present invention and nonwoven fabrics containing these fibers can be incorporated into various textile products. Examples of such textile products include skincare sheets in the cosmetics field.

[0024] The fibers of the present invention, having the enhanced hydrophobicity described above, preferably have a wet tensile strength test value of 32 mN / m or more and 59 mN / m or less, and more preferably 37 mN / m or less.

[0025] (Method for testing the wet tensile strength of fibers) First, using the fiber to be measured, the basis weight was 20 g / m². 2Prepare a 30mm x 30mm nonwoven fabric. In an environment with an ambient temperature of 23°C, stretch the prepared nonwoven fabric horizontally in the air and drop 0.02 mL of the wetting tension test solution onto the upper surface of the nonwoven fabric using a dropper. Two seconds after dropping the test solution, visually observe the state of the test solution on the upper surface of the nonwoven fabric. If the test solution permeates in the thickness direction of the nonwoven fabric or diffuses in the surface direction, change to a test solution with a higher surface tension and perform the same procedure. If the test solution does not permeate the nonwoven fabric and the droplet remains on the upper surface of the nonwoven fabric, or if there is almost no wetting on the upper surface without diffusion in the surface direction, the surface tension of the test solution used in the immediately preceding dropping operation, i.e., the test solution with the highest surface tension that permeated or diffused through the nonwoven fabric, is taken as the wetting tension of the nonwoven fabric at an ambient temperature of 20°C. As the wettability test solution, we use "Wettability Test Mixture" (product name) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. This is a mixture of ethylene glycol monoethyl ether, formamide, methanol, and water, prepared in accordance with JIS K 6768:1999.

[0026] The fibers of the present invention, having the enhanced hydrophobicity described above, preferably have a "water contact angle measured when the compound contained in component B is made into a plate" of 92° or more and 108° or less.

[0027] (Method for measuring the contact angle of the compound contained in component B) First, the compound containing component B is heated and melted to form 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 droplet method. Specifically, the automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used as the measuring device. Deionized water is used as the dropping solution. In an environment with a temperature of 25 degrees Celsius and a relative humidity (RH) of 65%, the amount of liquid ejected from the inkjet-type water droplet ejection unit (CTC-25 pulse injector manufactured by Cluster Technology Co., Ltd., with an ejection unit pore diameter of 25 μm) is set to 1 μm, and water droplets are dropped directly onto the molding plate. The dropping process is recorded by a high-speed recording device connected to a horizontally mounted camera. For later image analysis, a personal computer with a built-in high-speed capture device is preferable as the recording device. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of a water droplet landing on a fiber removed from the nonwoven fabric is analyzed using the included FAMAS software (software version 2.6.2, analysis method: droplet method, analysis method: θ / 2 method, image processing algorithm: non-reflective, image processing image mode: frame, threshold level: 200, curvature correction: none), and the angle between the air-contacting surface of the water droplet and the molded plate is calculated and defined as the contact angle.

[0028] In the fibers of the present invention, various aliphatic polyesters can be used as component A. For example, it is preferable to include 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 referred to as PDO). Among these, it is more preferable that the compound be biodegradable. This reduces the environmental impact when the fibers of the present invention are released into the environment (for example, when a nonwoven fabric made using the fibers of the present invention is used as a cosmetic material and the fibers are washed away during cleaning for reuse, etc.). Here, "biodegradability" refers to polyester with a biodegradability of 30% or more, as measured in accordance with JIS K 6953-1. Specific examples of biodegradable aliphatic polyesters include, preferably, one or more selected from PCL, PBS, PBSA, and PDO. Among these, PCL is preferred due to its high biodegradability.

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

[0030] The "fatty acid having 14 to 24 carbon atoms" in (1) above preferably includes one or more selected from, for example, stearic acid, behenic acid, and myristic acid. Among these, stearic acid and behenic acid are more preferable because they have excellent storage stability in combination with component A, a high melting point, and high storage stability of the fibers, which allows the hydrophobic treatment effect to last even longer.

[0031] The "fatty acid ester compound in which a polyhydric alcohol and two or more fatty acids are bonded, and the total number of carbon atoms of all fatty acid groups is 24 or more" in (2) above preferably includes, for example, one or more selected from sorbitan fatty acid ester compounds. From the viewpoint of enhancing the hydrophobicity of the fibers of the present invention, it is preferable that these include diesters or higher rather than monoesters. Furthermore, in the compounds included in the fatty acid ester compound of (2) above, each esterified fatty acid group preferably has a skeleton in which carbon atoms are single-bonded, and more preferably the skeleton is linear. Moreover, as mentioned above, it is preferable that the fatty acid group does not have repeating units.

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

[0033] The "sphingolipids with 24 or more carbon atoms" in (3) above preferably include one or more selected from, for example, sphingoglycolipids and sphingophospholipids. From the viewpoint of obtaining fibers with sufficiently low wettability, component B preferably contains one or more selected from (1) to (3) above. From the viewpoint of obtaining sustained hydrophobicity in water and stability of 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 those in (1) above.

[0034] In the fiber of the present invention, from the viewpoint of further enhancing the hydrophobicity and making it even more difficult to wet, it is preferable that component A constitutes the core layer of the fiber and extends in the longitudinal direction (fiber length direction) of the fiber, and that a portion of component B is arranged on the fiber surface (i.e., the surface of the core layer of component A). In this case, although component B is present inside the fiber, a portion of it is exposed on the fiber surface side. Furthermore, component B inside the fiber may be mixed with the thermoplastic resin of component A. From a similar viewpoint, it is preferable that a portion of component B covers the surrounding surface of the core layer 2 of component A as an epidermal layer 3, as shown in the constituent fiber 1 in Figure 1. In this case, the interface between the component concentrations of the epidermal 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 be blurred. Furthermore, the epidermal layer 3 of component B may cover the entire fiber surface or it may cover only a portion of it. In the case of partial coverage, the arrangement may be a sea-island structure in which the region with the epidermal layer 3 of component B includes a region without the epidermal layer 3 of component B, or the region with the epidermal layer 3 of component B may be separated from the region without the epidermal layer 3 of component B.

[0035] In the fibers of the present invention, by including components A and B in specific proportions, it is possible to produce finer fibers using the manufacturing method described later, and the uniformity of the fiber diameter can also be improved. Therefore, it is preferable that the nonwoven fabric produced using the fibers of the present invention has an average fiber diameter of 0.1 μm or more and 5.0 μm or less. Nonwoven fabrics containing such ultrafine fibers as constituent fibers have a fine texture and a soft feel. In addition, they have higher capillary strength. When this nonwoven fabric is impregnated with various hydrophobic solutions to create a cosmetic material, it is less burdensome on the skin, and the sustained release of the hydrophobic solution to the skin is enhanced, allowing its effects to last longer. Furthermore, because the hydrophobic treatment effect tends to last longer, it can be reused after washing. In this case, if component A contains a biodegradable compound, the environmental burden will be reduced even if some of the fibers are washed away during the washing process.

[0036] From the above viewpoint, 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. Furthermore, from the viewpoint of improving the strength of the fibers, the average fiber diameter is more preferably 0.2 μm or more, and even more preferably 0.5 μm or more.

[0037] (Method for measuring average fiber diameter) From two-dimensional images obtained by scanning electron microscopy, 200 fibers are randomly selected, removing defects such as fiber clumps, fiber intersections, and polymer droplets. The width of each individual fiber perpendicular to its longitudinal direction (the length of a line drawn through the center of the fiber in a cross-section perpendicular to the longitudinal direction of the constituent fiber) 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. If the cross-section perpendicular to the longitudinal direction of the fiber is not circular, the above average fiber diameter is converted to an equivalent diameter.

[0038] Next, preferred embodiments of the method for producing the fibers of the present invention will be described. The method for producing the fibers in 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. Component A used here is an aliphatic polyester, as described above. Component B is, as described above, one or more compounds selected from (1) to (3) above, with a solidification point of 30°C or higher and being water-insoluble. It is preferable to perform the steps of (I) heating and melting the thermoplastic resin composition (component A + component B) and (II) extruding it from a nozzle.

[0039] In step (I) above, for example, component A and component B are introduced into a housing connected to the hopper via a hopper. Components A and B are heated and melted in the housing to produce a molten resin mixture of the thermoplastic resin composition (hereinafter also simply referred to as the resin mixture molten liquid). This resin mixture molten liquid is pushed towards a discharge nozzle by the rotation of a screw or by pressure from air, etc., and supplied to the discharge port at the tip of the nozzle. In this case, there may be one nozzle or multiple nozzles. Next, in step (II) above, 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, becoming fibers. At this time, by appropriately setting the hole diameter of the discharge port at the tip of the nozzle, the aforementioned ultrafine fibers can be spun. This makes it possible to manufacture a nonwoven fabric with an average fiber diameter of 5 μm or less. In this step, when components A and B with different solidification points are spun, the component with the higher solidification point solidifies faster during spinning and becomes more stable. A stable state is formed at the interface between air and molten resin, so the component that solidifies easily is formed on the air side, and due to the difference in solidification points, the aforementioned core layer 2 and surface layer 3 are easily formed.

[0040] In step (II) above, the discharge 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. Furthermore, the discharge rate 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] From the viewpoint of suppressing breakage during spinning, the viscosity of the resin mixture molten liquid at the nozzle discharge is preferably 1 Pa·s or higher, more preferably 2 Pa·s or higher, and even more preferably 5 Pa·s or higher. Furthermore, 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 reducing viscosity and making it easier to thin the fibers.

[0042] (Method for measuring the viscosity of a resin mixture molten liquid) The melt viscosity will be measured using a rotary rheometer. Specifically, the measurement will be performed using an Anton Paar MCR305 instrument. A Φ50 mm parallel plate will be used as the measurement jig, and the shear rate will be 0.1 s. -1 Viscosity measurements are performed using the following method. The measurement temperature is set to match the spinning conditions. The sample is placed on the plate, and after the resin melts, the clearance is set to 1 mm, and any portion exceeding the Φ50 mm parallel plate is trimmed. Then, wait until the sample reaches the measurement temperature, and then start the measurement. The viscosity value obtained is taken 100 seconds after the rotation starts and used as the measured value.

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

[0044] From the viewpoint of making the above-mentioned stretching more effective, the temperature of the heated fluid is preferably higher than the solidification point of component A. Specifically, the difference between the temperature of the heated fluid and the solidification point of component A is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher. Furthermore, from the viewpoint of suppressing resin decomposition, 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.

[0045] In the fiber manufacturing method of this embodiment, it is preferable to perform an electrospinning treatment in step (II) above. This electrospinning treatment may be performed together with the heating fluid spraying treatment described above, or it may be performed in place of the heating fluid spraying treatment. Electrospinning, also known as electrospinning, is a process that directly or indirectly charges a nozzle from which resin is discharged, thereby imparting an electric charge to the resin and spinning it. This allows for more aggressive stretching and the formation of even finer fibers. For example, a charging electrode and a high-voltage generator connected to the charging electrode are placed at a corresponding position, spaced apart from the nozzle. With this configuration, a high voltage can be applied between the nozzle tip and the charging electrode to create an electric field between them, thereby charging the resin molten mixture discharged from the nozzle tip. The charging electrode is preferably made of a conductive material such as metal or covered with a dielectric material.

[0046] In the fiber manufacturing method of this embodiment, in addition to components A and B, other agents may be included as long as they do not impair the effects of the present invention. For example, from the viewpoint of increasing the amount of charge, examples include charge modifiers, lubricants, antistatic agents, surfactants, plasticizers, etc. In addition, antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, etc. may also be included.

[0047] In this way, nonwoven fabric can be suitably manufactured by collecting the fibers obtained by the fiber manufacturing method of this embodiment and forming them into a sheet. For example, a resin mixed molten liquid discharged from the nozzle tip can be cooled and stretched, then collected in the collection section and deposited into a sheet to form a nonwoven fabric. From the viewpoint of improving collection efficiency, the collection section preferably includes a collection electrode and a high-voltage generator connected to the collection electrode. The collection electrode and high-voltage generator in this collection section may also serve as the aforementioned charging electrode and high-voltage generator, or they may be provided separately. As described above, in the method for manufacturing nonwoven fabric of this embodiment, ultrafine fibers can be produced uniformly, efficiently, and at high speed from a resin mixture molten liquid of component A and component B. Therefore, the nonwoven fabric of the present invention, with a larger surface area, can be industrially and efficiently manufactured on an actual production line.

[0048] With regard to the embodiments described above, the present invention further discloses the following fibers, nonwoven fabrics and textile products.

[0049] <1> The fiber contains 50% by mass or more of component A and 10% by mass or more of component B, with component A and component B contained within the fiber. The aforementioned component B is a fiber that has a solidification point of 30°C or higher and is insoluble in water. Component A: Aliphatic polyester Component B: One or more compounds selected from (1) to (3) below. (1) One or more compounds selected from fatty acids with 14 to 24 carbon atoms. (2) One or more fatty acid ester compounds selected from fatty acid ester compounds in which a polyhydric alcohol is bonded to two or more fatty acids, the sum of the number of carbon atoms of all fatty acid groups is 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) is 1 or more. (3) One or more compounds selected from sphingolipids having 24 or more carbon atoms.

[0050] <2> A portion of component B is arranged on the surface of the fiber, <1> The fibers described above. <3> The aforementioned component B The compound includes a compound whose water contact angle, measured in a plate-like form, is 92° or greater. <1> or <2> The fibers described above. <4> The wet tensile strength test value of the aforementioned fiber is 32 mN / m or more and 59 mN / m or less. <1> ~ <3> The fiber described in any one of the following. <5> The aforementioned component A contains a biodegradable compound, <1> ~ <4> The fiber described in any one of the following. <6> The aforementioned biodegradability refers to a degree of biodegradation of polyester of 30% or more, as measured in accordance with JIS K 6953-1. <5> The fibers described above. <7> Component A comprises one or more selected from polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polydioxanone, as described above. <1> ~ <6> The fiber described in any one of the following. <8> The above component A contains polycaprolactone, <1> ~ <7> The fiber described in any one of the following. <9> The content of 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, relative to the total mass of the fiber. <1> ~ <8> The fiber described in any one of the following. <10> The aforementioned component B includes a compound having a solidification point of 40°C to 100°C, preferably 50°C to 90°C, and more preferably 70°C to 80°C. <1> ~ <9> The fiber described in any one of the following. <11> The compounds in (2) and (3) above include compounds having 24 or more carbon atoms and 36 or fewer carbon atoms. <1> ~ <10> The fiber described in any one of the following. <12> The wet tensile strength test value of the aforementioned fiber is 32 mN / m or more and 37 mN / m or less. <1> ~ <11> The fiber described in any one of the following. <13> The aforementioned component B includes a compound whose water contact angle, measured in a plate-like form, is 92° or more and 108° or less. <1> ~ <12> The fiber described in any one of the following. <14> The compound in (1) comprises one or more selected from stearic acid, behenic acid, and myristic acid. <1> ~ <13> The fiber described in any one of the following. <15> The compound in (2) comprises one or more selected from sorbitan fatty acid ester compounds. <1> ~ <14> The fiber described in any one of the following. <16> In the compound (2) above, The sorbitan fatty acid ester compound is sorbitan distearate, sorbitan oleate Includes one or more selected from Vitan, Preferably containing 1 or 2 or more sorbitan distearates The aforementioned <15> The fibers described above. <17> The compound in (2) comprises one or more compounds selected from diesters or higher, <1> ~ <16> The fiber described in any one of the following. <18> The compound in (2) above includes a compound in which the fatty acid group does not have repeating units. <1> ~ <17> The fiber described in any one of the following. <19> The compound in (2) above has a skeleton in which each esterified fatty acid group is single-bonded to carbon atoms, preferably the skeleton is linear. <1> ~ <18> The fiber described in any one of the following. <20> The compound in (3) comprises one or more selected from sphingoglycolipids and sphingophospholipids. <1> ~ <19> The fiber described in any one of the following. <21> The aforementioned component B comprises one or more compounds selected from the compounds of (1) to (3), and the aforementioned compound (1) comprises one or more compounds selected from stearic acid and behenic acid. <1> ~ <20> The fiber described in any one of the following.

[0051] <22> The aforementioned <1> ~ <21> A nonwoven fabric containing the fibers described in any one of the following: <23> The average fiber diameter of the nonwoven fabric is 0.1 μm or more and 5 μm or less. <22> The nonwoven fabric described above. <24> The average fiber diameter of the nonwoven fabric is 0.5 μm or more and 2.5 μm or less. <23> The nonwoven fabric described above. <25> The aforementioned <1> ~ <21> The fibers described in any one of the above, or the above <22> ~ <24> A textile product containing a nonwoven fabric as described in any one of the following. <26> The aforementioned textile product is a skincare sheet. <25> Textile products as described above. [Examples]

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

[0053] (Examples 1-3) Component A was PCL and component B was behenic acid, and they were mixed in the proportions shown in Table 1 to prepare a thermoplastic resin composition. A molten solution of this thermoplastic resin composition was prepared, and fiber samples of Examples 1 to 3 were produced by melt electrospinning using one nozzle. Simultaneously with spinning, the fibers were deposited to produce nonwoven fabric samples of Examples 1 to 3 (basis weight 5 g / m²). 2 A nonwoven fabric sample was prepared. The average fiber diameter of the sample was 2 μm. In the molten electrospinning method, the applied voltage was -10 kV. Furthermore, the molten thermoplastic resin composition discharged from the nozzle was stretched by blowing a heated fluid at 180°C onto it. As shown in Figure 1, the fiber samples of Examples 1 and 2 had a structure in which the surface layer of component B covered the core layer of component A.

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

[0055] (Comparative Example 1) The fiber and nonwoven fabric samples 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) Fiber samples and nonwoven fabric samples for Comparative Example 2 were prepared in the same manner as in Example 1, except that the content of component B was set to 5% by mass. In the fiber samples of Comparative Example 2, no structure in which component B was arranged on the fiber surface was observed.

[0057] (Comparative Example 3) Except for replacing component B with a compound having 10 carbon atoms (less than 14), an attempt was made to prepare the fiber and nonwoven fabric samples of Comparative Example 3 in the same manner as in Example 1. However, smoke was generated during the spinning process, making it impossible to obtain the fiber and nonwoven fabric samples. (Comparative Example 4) Fiber samples and nonwoven fabric samples were prepared in the same manner as in Example 1, using only the compounds shown 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. Then, the liquid compounds shown in Table 1 were added to the fiber samples and nonwoven fabric samples, and the samples were immersed to prepare the fiber samples and nonwoven fabric samples of Comparative Example 4.

[0058] For each of the examples and comparative examples described above, the wetting tension and the contact angle of component B were measured. These were measured based on the (test method for wetting tension of fibers) and (measurement method for the contact angle of component B) described above. Furthermore, the persistence of the hydrophobic treatment effect (enhanced hydrophobicity) in water was examined using the (method for confirming the persistence of hydrophobic properties in fibers) described below. It was measured based on the following criteria. (Method for confirming the persistence of hydrophobic properties in fibers) In an environment of 23°C and 50% relative humidity (RH), 50 mL of deionized water was placed in a 100 mL beaker, 0.5 g of fiber was taken out, and it was left standing in the deionized water for 24 hours. After that, the fiber was removed, placed between filter paper, and loaded with a 2 kg weight for 10 minutes to remove as much deionized water as possible. To further remove the deionized water from the fiber, it was dried under reduced pressure. Specifically, it was dried at 40°C and -0.04 MPa for 24 hours. After that, the fiber was subjected to a wet tensile strength test in the same manner as described above (Method for testing the wet tensile strength of the fiber), and it was confirmed that the value was the same as the value before storage in deionized water. If the change in value was 0, it was determined that the hydrophobic properties had been maintained. (Change in value) = (Wetting test solution value before storage in water) - (Wetting test solution value after storage in water)

[0059] [Table 1]

[0060] As shown in Table 1, compared to Comparative Examples 1 and 2, which either did not contain component B or contained it at a concentration of 5%, Examples 1 to 6 demonstrated that the wetting tension of the spun fibers was 59 mN / m or less and that they maintained their hydrophobicity in water. Furthermore, compared to Comparative Example 3, which used a compound with a smaller carbon number instead of component B, Examples 1 to 6 successfully obtained fiber samples. Compared to Comparative Example 4, which used polypropylene instead of component A and added component B later, Examples 1 to 5 showed no change in the persistence of their properties in water compared to 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 component A and 10% by mass or more of component B, with component A and component B contained within the fiber. The aforementioned component B is a fiber that has a solidification point of 30°C or higher and is insoluble in water. Component A: Aliphatic polyester Component B: One or more compounds selected from (1) to (3) below. (1) One or more compounds selected from fatty acids having 14 to 24 carbon atoms. (2) One or more fatty acid ester compounds selected from fatty acid ester compounds in which a polyhydric alcohol is bonded to two or more fatty acids, wherein the total number of carbon atoms of all fatty acid groups is 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) is 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 arranged on the surface of the fiber.

3. The fiber according to claim 1, wherein component B contains a compound whose water contact angle, measured in a plate-like form, is 92° or greater.

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

5. The fiber according to claim 1, wherein component A contains a biodegradable compound.

6. The fiber according to claim 1, wherein component A contains polycaprolactone.

7. A nonwoven fabric containing the fibers described in any one of claims 1 to 6.

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 described in any one of claims 1 to 6.

10. A textile product comprising the nonwoven fabric described in claim 7.

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