Fiber

Abstract

Provided is a fiber which contains 50 mass% or more of the following component A and 10 mass% or more of the following component B relative to the mass of the entire fiber, and which contains the component A and the component B. Component A: an aliphatic polyester; component B: an ester compound of a polyol and a fatty acid, said compound being water-insoluble, having a curing point of 30 DEG C or higher, and containing a fatty acid group having 14 or more and less than 24 carbon atoms.

Description

Technical Field

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

[0002] Fibers are used in various applications such as filters, sanitary materials, cosmetic materials, and medical materials (for example, Patent Documents 1 to 4). For example, in the medical field, ultrafine fibers (for example, fiber diameter of 50 μm or less) are being studied as scaffold materials, and in the cosmetic field, they are being studied as skin care sheets, etc. Fibers sometimes impregnate active ingredients in liquid form, and it is important to control the physical properties of the fiber surface such as hydrophilicity and hydrophobicity according to the physical properties of the impregnated liquid. With the development of spinning technology, many studies have been conducted on making fibers from thermoplastic resins. However, thermoplastic resins are generally hydrophobic, and their uses are limited when the fibers maintain their original surface physical properties.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-143157

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-169201

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2012-207350

[0008] Patent Document 4: International Publication No. 2006 / 022430 Summary of the Invention

[0009] The present invention provides a fiber containing 50% by mass or more of the following Component A and 10% by mass or more of the following Component B, based on the mass of the entire fiber, and the Component A and the Component B are contained inside the fiber.

[0010] Component A: aliphatic polyester;

[0011] Component B: an ester compound of a polyol and a fatty acid, which is water-insoluble, has a solidification point of 30°C or higher, and contains a fatty acid group having 14 or more and less than 24 carbon atoms.

[0012] The above and other features and advantages of the present invention will become clearer by appropriate reference to the accompanying drawings and according to the following description. Brief Description of the Drawings

[0013] Figure 1 It is a cross-sectional perspective view schematically showing an embodiment of the fiber according to the present invention. Detailed Description

[0014] The present invention relates to a fiber that is easily wetted by an aqueous solvent and that also easily maintains a hydrophilic property in water for a long time.

[0015] When the above-described fiber is used in a living body or on the skin, an aliphatic polyester is sometimes preferably used as a raw material of the fiber. The wettability of a fiber using an aliphatic polyester by itself with respect to an aqueous solvent cannot be said to be sufficient. Therefore, conventionally, a hydrophilizing agent has usually been applied to the fiber surface. However, since it is a coating or attachment treatment, when the fiber is present in water, the hydrophilizing agent dissolves out and the hydrophilization treatment effect is reduced. Therefore, there is still room for improvement.

[0016] The fiber of the present invention is easily wetted by an aqueous solvent and also easily maintains a hydrophilic property in water for a long time.

[0017] Hereinafter, the fiber of the present invention will be described.

[0018] In the fiber of the present invention, as a constituent, it preferably contains 50% by mass or more of an aliphatic polyester (hereinafter referred to as component A), and 10% or more of an ester compound of a polyol and a fatty acid (hereinafter referred to as component B). The above-described content ratios of component A and component B respectively refer to the ratios when the total mass of the fiber of the present invention is set to 100% by mass.

[0019] Component A and component B are preferably contained inside the fiber.

[0020] Component B preferably has a solidification point of 30°C or higher.

[0021] Component B is preferably water-insoluble.

[0022] Component B preferably contains a fatty acid group having 14 or more and less than 24 carbon atoms. There may be a plurality of such fatty acid groups.

[0023] (Extraction method of each constituent)

[0024] Fibers are taken out from the fiber aggregate to be measured so that the mass becomes about 1 g. When the above-described fiber aggregate is a non-woven fabric, a slice of the above-described mass is cut out. The constituent components are extracted from the taken-out fibers or slices using various solvents, and each constituent component is separately separated by HPLC (high performance liquid chromatography).

[0025] (Measurement method of solidification point)

[0026] The above-mentioned "solidification point", also known as the solidification temperature, refers to the peak temperature of the exothermic peak that first appears when the sample is gradually heated by differential scanning calorimetry (DSC) and then cooled at a rate of 5°C per minute after melting. This measurement is carried out by operating as described below. The components extracted by the above-mentioned (extraction method of each component) are sealed in an aluminum sample pan and heated, and gradually heated at a rate of 5°C per minute. After reaching 200°C by heating, it is gradually cooled at a rate of 5°C per minute within 600 seconds. Then, the measurement is ended when it reaches 0°C.

[0027] In addition, the above-mentioned peak temperature refers to the temperature at which the heated component starts to solidify by cooling. The above-mentioned "molten state" refers to the state in which the above-mentioned component flows when an external force is applied, for example, it refers to the state of being heated above the melting point of the target component. The above-mentioned "solidification" refers to crystallization, or when crystallization is not observed, it refers to glass transition.

[0028] (Method for measuring the content ratio of Component A and Component B)

[0029] The components extracted by the above-mentioned (extraction method of each component) are dissolved in deuterated solvents in which each component is soluble, and proton NMR is used to identify each component. Thus, the components corresponding to Component A and B are identified.

[0030] Next, the component is extracted from the fiber aggregate with a solvent that can dissolve the identified Component A or B, and its content ratio is determined.

[0031] For example, the fiber aggregate is immersed in an organic solvent that can dissolve Component B for 24 hours to extract Component B. The fiber is taken out from the organic solvent and dried under the conditions of 40°C and reduced pressure drying of -0.04 MPa for 24 hours. Thereafter, by measuring the mass of the dried fiber, the mass% of Component B can be measured.

[0032] Content ratio of Component B (mass%) = 100 - (mass of fiber after reduced pressure drying / initial mass of fiber) × 100

[0033] (Method for measuring the content of Component A and Component B inside the fiber)

[0034] For each component identified by the above-mentioned (method for measuring the content ratio of Component A and Component B), the fiber to be measured is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS). By analyzing the cross-section obtained by cutting the fiber in a direction perpendicular to the length direction during the measurement, it is determined whether Component A and Component B are contained inside the fiber.

[0035] Component A, which accounts for 50% by mass or more of the total mass of the fiber, preferably serves as the main base agent of the fiber of the present invention. By using an aliphatic polyester having a plurality of polar ester bonds as the main base agent, the affinity of the fiber of the present invention for organisms can be improved. In addition, the fiber of the present invention can be made into ultrafine fibers with high hydrophilicity, which is meaningful as a cosmetic material, for example.

[0036] From the viewpoint of further enhancing the above effects, the content ratio of component A relative to the total mass of the fiber is preferably set at 55% by mass or more, more preferably 60% by mass or more, and still more preferably 75% by mass or more.

[0037] In addition, from the viewpoint of facilitating the manifestation of hydrophilicity, the content ratio of component A relative to the total mass of the fiber is preferably set at 90% by mass or less, more preferably 87% by mass or less, and still more preferably 85% by mass or less.

[0038] Component B is preferably used as an additive in the fiber of the present invention and accounts for 10% by mass or more of the total mass of the fiber. Thereby, hydrophilicity is imparted to the fiber of the present invention. Moreover, the fiber of the present invention becomes easily wettable with an aqueous solvent. The "aqueous solvent" mentioned here refers to a solvent mainly composed of water, and an organic solvent miscible with water may be added in a small amount. In addition, it may also be a solvent mainly composed of water in which an oil phase is emulsified and dispersed.

[0039] Component B preferably contains a plurality of hydroxyl groups in the polyol moiety, and preferably has less than 24 carbon atoms in the fatty acid group. At this time, 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 preferably 0.6 or less. With these configurations, it contributes to the above-mentioned hydrophilicity. 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-mentioned (method for measuring the content ratio of component A and component B).

[0040] From this viewpoint, component B preferably contains a compound having no repeating unit in the fatty acid group.

[0041] In addition, component B preferably contains a compound having an ester structure and a hydrophobic group constituting the fatty acid group. Thereby, it has a basic structural similarity to component A. Therefore, the compatibility of component B with component A is high, and component B is not easily separated from component A in the fiber of the present invention. In addition, in the manufacturing method described later, component B is well dispersed in component A, and spinning can be stably carried out. This is technically meaningful in the manufacture of ultrafine fibers.

[0042] In addition, from the viewpoint of having a structural similarity with component A and the difficulty of separating component B from component A in the fiber, it is preferable that the fatty acid group of the compound contained in component B is a saturated fatty acid group. From the viewpoint of having a structural similarity with component A, it is further preferable that the above-mentioned saturated fatty acid group is a straight-chain saturated fatty acid.

[0043] It is preferable that the molecular weight of the hydrophilic group of the compound contained in component B is 100 g / mol or less. Since the molecular weight of the hydrophilic group is small, steric hindrance can be better suppressed, and the molecules of component B can be easily arranged closely. As a result, component B can be more effectively arranged on the outer side of the fiber, and even fine fibers can be hydrophilized more effectively. Here, the molecular weight of the hydrophilic group can be calculated as the value obtained by subtracting the total molecular weight of the fatty acid group from the molecular weight of component B.

[0044] The "fatty acid group" in component B refers to the chemical structure part derived from fatty acids. Specifically, the above-mentioned "fatty acid group" refers to the structure containing the hydrocarbon group of fatty acids and the carbonyl group bonded to the hydrocarbon group in the structure where a polyol and a fatty acid are bonded through an ester bond. The "number of carbon atoms" of the fatty acid group refers to the number of carbon atoms in the "structure containing the hydrocarbon group of fatty acids and the carbonyl group bonded to the hydrocarbon group" that constitutes the fatty acid group. Here, when the above-mentioned fatty acid group has a substituent, the number of carbon atoms of the substituent is also included in the above-mentioned "number of carbon atoms".

[0045] In addition, the "polyol part" in component B refers to the chemical structure part derived from polyols and is the part other than the above-mentioned "fatty acid group" in the ester compound of component B.

[0046] It is preferable that component B is water-insoluble. The "water-insoluble" mentioned here means that the proportion of the water-insoluble component measured by the following method is 85% by mass or more.

[0047] It is preferable that component B contains a fatty acid group having 14 or more and less than 24 carbon atoms. In addition, it is preferable that esterification occurs between the polyol part and the fatty acid group. This contributes to the above-mentioned water-insolubility.

[0048] In addition, it is preferable that the solidification point of component B is 30 °C or higher. As a result, component B exists in a solid state at room temperature (23 °C) and is not easily dissolved out of water.

[0049] (Method for measuring the water-insolubility of component B)

[0050] Extract by the above (extraction method of each constituent), and determine Component B by the above (measurement method of the content ratio of Component A and Component 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 particulate form with a diameter of 1 mm or less to the deionized water, and let it stand for 24 hours. Then, in order to remove Component B, perform vacuum filtration using filter paper. At this time, use filter paper with a retention particle size of 5 μm (for example, qualitative filter paper No. 2 manufactured by ADVANTEC). Before performing vacuum filtration, pre-measure the mass of the filter paper. Vacuum-dry the filter paper and Component B during vacuum filtration for 24 hours. Specifically for this vacuum drying, set the temperature to 40 °C and the degree of vacuum to -0.04 MPa.

[0051] Measure the mass of the filter paper and Component B on the filter paper after vacuum drying, and subtract the mass of the filter paper before vacuum filtration, thereby calculating the mass of the water-insoluble part of Component B. Calculate the proportion of the water-insoluble component in Component B using the following formula (1).

[0052] (Proportion of water-insoluble component) = ((mass of filter paper and Component B after vacuum drying - mass of filter paper before vacuum filtration) / mass of Component B during measurement) × 100 (1)

[0053] From the perspective of further enhancing the above effects, the content ratio 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 still more preferably 18% by mass or more.

[0054] In addition, the content ratio 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 still more preferably 25% by mass or less. By setting it below the above upper limit, the strength of the fiber can be maintained.

[0055] From the perspective of making the above effects better, the solidification point of the compound contained in Component B is preferably 40 °C or higher, more preferably 50 °C or higher, and still more preferably 70 °C or higher.

[0056] In addition, from the perspective 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 still more preferably 80 °C or lower.

[0057] In the compound contained in Component B, from the perspective of further enhancing the above water-insolubility, the number of carbon atoms in the fatty acid group is preferably 16 or more, more preferably 18 or more, and still more preferably 20 or more.

[0058] In addition, from the viewpoint of making the hydrophilicity of the fibers of the present invention more distinct, the number of carbon atoms in the fatty acid group is preferably 23 or less, more preferably 22 or less.

[0059] In the fibers of the present invention, by containing Component A and Component B in the above-mentioned content ratios, even when the fibers of the present invention come into contact with water or are in water, Component B is not easily dissolved in water and easily maintains hydrophilicity. As a result, the fibers of the present invention are easily wetted by aqueous solvents, and at the same time, the property of being hydrophilized can be easily maintained for a long time even in water.

[0060] Such fibers of the present invention can be made into sheet-like non-woven fabrics, for example, and impregnated with various water-soluble liquids as needed for use. The fibers of the present invention and the non-woven fabrics containing the fibers can be included as materials constituting various fiber products. As such fiber products, for example, stent materials in the medical field, skin care sheets in the cosmetic field, etc. can be cited.

[0061] As the fibers having the above-mentioned easy wettability, the wetting tension test value of the fibers shown below is preferably 73 mN / m or more. The higher the above-mentioned wetting tension test value, the higher the wettability of the fibers of the present invention.

[0062] (Method for testing the wetting tension of fibers)

[0063] First, using the fibers to be measured, prepare a non-woven fabric with a basis weight of 20 g / m 2 and a size of 30 mm × 30 mm. In an environmental area with an atmosphere temperature of 23°C, the prepared non-woven fabric is horizontally spread and set in the air, and 0.02 mL of a wetting tension test liquid is dropped on the upper surface of the non-woven fabric using a glass pipette. After 2 seconds from the dropping of the test liquid, the state of the test liquid on the upper surface of the non-woven fabric where the above dropping was performed is visually observed. In this observation, when the test liquid penetrates in the thickness direction of the non-woven fabric or diffuses in the plane direction, a test liquid with a greater surface tension is changed and the same operation is performed. And, when the test liquid cannot penetrate the non-woven fabric and the liquid droplet remains on the upper surface of the non-woven fabric, or when there is no diffusion in the plane direction and basically no wetting is confirmed on the upper surface, the surface tension of the test liquid used in the dropping operation before this case, that is, the test liquid with the greatest surface tension among the test liquids that penetrate or diffuse through the non-woven fabric, is taken as the wetting tension of the non-woven fabric at an atmosphere temperature of 20°C. As the wetting tension test liquid, the "Mixed Liquid for Wetting Tension Test" (trade name) manufactured by Fuji Film Wako Pure Chemical Corporation is used. This is a mixed liquid of ethylene glycol monoethyl ether, formamide, methanol, and water prepared according to JIS K 6768:1999.

[0064] Among the fibers of the present invention, as the fiber having the above hydrophilicity, the "contact angle of water measured by forming the compound contained in Component B into a plate shape" shown below is preferably 46° or less, more preferably 9.2° or more and 45.9° or less. The smaller the above contact angle, the higher the hydrophilicity.

[0065] (Measurement method of the contact angle of the compound contained in Component B)

[0066] First, the compound contained in Component B is heat-melted and formed into a plate shape. The size of the formed plate is formed to be 5 cm × 5 cm, and the thickness is formed to be 1 mm. For the above formed plate, the contact angle is measured using the droplet method.

[0067] Specifically, as the measuring device, an automatic contact angle measuring instrument MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. As the dropping liquid, deionized water is used. In an environmental area with a temperature of 25 degrees and a relative humidity (RH) of 65%, the liquid volume discharged from the inkjet water droplet discharge part (Pulse Injector CTC-25 manufactured by CLUSTER TECHNOLOGY Co., Ltd., discharge part aperture of 25 μm) is set to 1 μm, and the water droplet is dropped directly above the formed plate. The dropping state is photographed by a high-speed photographing device connected to a horizontally arranged camera. From the viewpoint of post-image analysis or image analysis, the photographing device is preferably a personal computer equipped with a high-speed capture device. In this measurement, images are taken every 17 msec. In the photographed image, the initial image when the water droplet drops onto the fiber taken out from the non-woven fabric is subjected to image analysis through the attached software FAMAS (software version is 2.6.2, analysis method is the droplet method, analysis method is the θ / 2 method, image processing algorithm is non-reflection, image processing picture mode is frame mode, threshold level is set to 200, and curvature correction is not performed), and the angle formed by the surface where the water droplet contacts the air and the formed plate is calculated as the contact angle.

[0068] In the fibers of the present invention, various aliphatic polyesters can be used as the aliphatic polyester contained in Component A. For example, it is preferably contained 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 adipate succinate (hereinafter also referred to as PBSA), and polydioxanone (hereinafter also referred to as PDO).

[0069] Among them, compounds with biodegradability are more preferably included. Thereby, the environmental impact when the fibers of the present invention flow out into the environment (for example, when the non-woven fabric formed of the fibers of the present invention is used as a cosmetic material and is washed for reuse or the like, and the fibers flow out) can be reduced. In addition, the "biodegradability" as mentioned herein means that the biodegradation degree of the polyester measured according to JIS K6953-1 is 30% or more.

[0070] As specific examples of the biodegradable aliphatic polyester, it is preferable to include one or more selected from PCL, PBS, PBSA, and PDO. Among them, PCL is preferably used in consideration of high biodegradability.

[0071] In the non-woven fabric of the present invention, as component B, various compounds with a solidification point of 30°C or higher, being water-insoluble, and containing a fatty acid group with 14 or more and less than 24 carbon atoms can be used. For example, it is preferable to include one or more selected from fatty acid glyceride compounds and polyglycerol fatty acid ester compounds. From the viewpoint of further improving the hydrophilicity of the fibers of the present invention, it is preferable that 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 0.6 or less.

[0072] In addition, the compound contained in component B preferably has a skeleton in which carbon atoms are bonded to each other by single bonds, and more preferably, this skeleton is a straight chain. Furthermore, the fatty acid group preferably does not have a repeating unit as described above.

[0073] As the above-mentioned fatty acid glyceride compound, for example, it is preferable to include one or more selected from behenyl glyceride, stearyl glyceride, and myristyl glyceride.

[0074] As the above-mentioned polyglycerol fatty acid ester compound, for example, it is preferable to include one or more selected from pentaglyceryl pentastearate and pentaglyceryl pentabehenate.

[0075] In such fibers of the present invention, from the viewpoint of further improving the above-mentioned hydrophilicity and making it easier to wet, it is preferable that component A constitutes the core layer of the fiber and extends in the length direction of the fiber (fiber length direction), and a part of component B is disposed on the fiber surface (that is, the surface of the core layer of component A). At this time, although component B exists inside the fiber, a part of it is exposed on the fiber surface side. In addition, the part of component B inside the fiber may have a part mixed with the thermoplastic resin of component A.

[0076] And, from the same viewpoint, it is preferable that as Figure 1Like the constituent fiber 1 shown, a part of component B coats the peripheral surface of the core layer 2 of component A as the skin layer 3. At this time, the interface of the component concentration between the skin layer 3 of component B and the core layer 2 of component A may not be clear, and preferably is blurred. In addition, the skin layer 3 of component B may coat the entire fiber surface or may coat partially. When coating partially, it may be configured as an island structure in which the region where the skin layer 3 of component B exists includes the region where the skin layer 3 of component B does not exist, or the region where the skin layer 3 of component B exists and the region where the skin layer 3 of component B does not exist may be separately arranged.

[0077] In the fiber of the present invention, by containing the above-mentioned component A and component B in a specific content ratio, it is possible to obtain finer fibers by the manufacturing method described later, and it is also possible to improve the uniformity of the fiber diameter.

[0078] Therefore, in the non-woven fabric made of the fiber of the present invention, it is preferable to set the average fiber diameter to 0.1 μm or more and 5 μm or less. The non-woven fabric containing such ultrafine fibers as constituent fibers has a delicate and soft skin feel like wood grain. In addition, the capillary force becomes higher. That is, the fiber of the present invention preferably has a fiber diameter of 0.1 μm or more and 5 μm or less.

[0079] When the non-woven fabric is impregnated with various hydrophilic solutions as cosmetic materials, for example, the burden on the skin is small, the sustained release property when the above-mentioned hydrophilic solution is provided to the skin can be improved, and its effect can be maintained for a longer time. In addition, since the hydrophilic property can be easily maintained for a long time, it can be reused by washing even after once used.

[0080] At this time, when component A contains a biodegradable compound, even if a part of the fiber flows out during the above-mentioned washing, the environmental load can be reduced.

[0081] From the above viewpoints, the average fiber diameter of the non-woven fabric made of the fiber of the present invention is preferably 4 μm or less, more preferably 2.5 μm or less.

[0082] In addition, from the viewpoint of improving the strength of the fiber, the above-mentioned average fiber diameter is more preferably 0.2 μm or more, and further preferably 0.5 μm or more.

[0083] That is, the fiber of the present invention more preferably has a fiber diameter within the above range.

[0084] (Method for measuring average fiber diameter)

[0085] From the two-dimensional image obtained by observation with a scanning electron microscope, 200 fibers are arbitrarily selected after removing defects such as fiber-free blocks, cross-sections of the fibers, and polymer droplets. The width orthogonal to the length direction (fiber length direction) of each fiber is measured (the length when a line passing through the center of the fiber is drawn in the cross-section orthogonal to the length direction of the fiber). The sum of these values is divided by the number of fibers measured to obtain the average fiber diameter of the nonwoven fabric to be measured. In addition, when the cross-section orthogonal to the length direction of the fiber is not circular, the above average fiber diameter is converted to an equivalent circular diameter.

[0086] Next, a preferred embodiment of the method for manufacturing the fiber of the present invention will be described.

[0087] The method for manufacturing the fiber of this embodiment preferably uses a thermoplastic resin composition containing 50% by mass or more of component A and 10% or more of component B. Component A used here is the aliphatic polyester as described above. Component B is, as described above, an ester compound of a polyol and a fatty acid, and the solidification point of this compound is 30°C or higher and it is water-insoluble, and it contains a fatty acid group having 14 or more and less than 24 carbon atoms.

[0088] Preferably, for the above thermoplastic resin composition (component A + component B), the step (I) of heating and melting and the step (II) of discharging from the nozzle are performed.

[0089] In the above step (I), for example, component A and component B are added into a box connected to the hopper through the hopper. Component A and component B are heated and melted in the box to produce a molten liquid of the above thermoplastic resin composition (hereinafter, also simply referred to as a resin mixed molten liquid). The resin mixed molten liquid is extruded toward the discharge nozzle by the rotation of a screw or the pressure of air or the like and supplied to the discharge port at the front end of the nozzle. The nozzle at this time can be one or multiple.

[0090] Next, in the above step (II), the supplied resin mixed molten liquid is discharged from the nozzle for spinning. As the discharged resin mixed molten liquid moves away from the discharge port at the front end of the nozzle, it is stretched, cooled, and gradually solidified to become a fiber. At this time, by appropriately setting the aperture of the discharge port at the front end of the nozzle, the above-mentioned ultrafine fiber can be spun. Thereby, a nonwoven fabric having a preferred average fiber diameter of 5 μm or less can be manufactured. In this step, if components A and B having different solidification points are spun, the component with a higher solidification point will solidify earlier during spinning, so it will become stable. Since a stable interface can be formed as the interface between air and the molten resin, the component that is easy to solidify appears on the air side, and due to the difference in solidification points, the above-mentioned core layer 2 and skin layer 3 are easily formed.

[0091] In the process of (II) above, the discharge rate of the molten liquid of the above thermoplastic resin composition from the nozzle is preferably 0.1 g / minute·nozzle or more, more preferably 0.2 g / minute·nozzle or more, and still more preferably 0.5 g / minute·nozzle or more.

[0092] In addition, the discharge rate of the molten liquid of the above thermoplastic resin composition from the nozzle is preferably 10 g / minute·nozzle or less, more preferably 5 g / minute·nozzle or less, and still more preferably 2 g / minute·nozzle or less.

[0093] From the viewpoint of suppressing filament breakage during spinning, the viscosity of the resin mixed molten liquid at the time of nozzle discharge is preferably 1 Pa·s or more, more preferably 2 Pa·s or more, and still more preferably 5 Pa·s or more.

[0094] In addition, from the viewpoint of reducing viscosity and facilitating fiber thinning, the viscosity of the resin mixed molten liquid at the time of nozzle discharge is preferably 20 Pa·s or less, more preferably 15 Pa·s or less, and still more preferably 10 Pa·s or less.

[0095] (Method for measuring the viscosity of the resin mixed molten liquid)

[0096] The melt viscosity is measured using a rotational rheometer. Specifically, the measurement is performed using an MCR305 device manufactured by Anton Paar. The measuring jig uses a parallel plate with a diameter of Φ50 mm, and the viscosity is measured at a shear rate of 0.1 s -1 For the temperature during measurement, the temperature is set according to the spinning conditions. The sample is placed on the plate, and after the resin is melted, the slit is set to 1 mm, and the part protruding from the Φ50 mm parallel plate is trimmed off. Then, wait until the sample reaches the measurement temperature, and then start the measurement. The viscosity value is obtained by using the value after 100 seconds as the measurement value after starting rotation.

[0097] The method for manufacturing the fiber of the present embodiment preferably performs the injection treatment of the heating fluid in the process of (II) above. This injection is performed on the state of the resin mixed molten liquid discharged from the nozzle before it is completely cured. By using the heat of the injected heating fluid, the discharged resin mixed molten liquid can be stretched more actively, and finer fibers can be formed. The injection of the heating fluid can be performed along the discharge direction of the resin mixed molten liquid, or in a direction intersecting the discharge direction.

[0098] From the viewpoint of more effectively performing the above stretching, the temperature of the above heating fluid is preferably higher than the curing point of component A.

[0099] Specifically, the difference between the temperature of the heating fluid and the curing point of component A is preferably 30 °C or more, more preferably 40 °C or more, and still more preferably 50 °C or more.

[0100] Further, from the viewpoint of suppressing the decomposition of the resin, the difference between the temperature of the heating fluid and the solidification point of Component A is preferably 150 °C or less, more preferably 140 °C or less, and further preferably 130 °C or less.

[0101] In the method for manufacturing the fiber of the present embodiment, an electrospinning treatment is preferably performed in the step (II) above. This electrospinning treatment can be performed together with the above-described injection treatment of the heating fluid, or can be performed in place of the injection treatment of the heating fluid.

[0102] The electrospinning treatment, also known as the electrospinning method, is a treatment in which a nozzle for discharging the resin is directly or indirectly charged, and a charge is imparted to the resin for spinning. Thereby, stretching can be performed more actively, and further finer fibers can be formed. For example, a charged electrode and a high-voltage generating device connected to the charged electrode are arranged at a position spaced apart from and corresponding to the nozzle. With this configuration, a high voltage can be applied between the front end of the nozzle and the charged electrode, an electric field can be formed between the two, and the resin mixed melt discharged from the front end of the nozzle can be charged. The charged electrode is preferably made of a conductive material such as metal or covered with a dielectric material.

[0103] In the method for manufacturing the fiber of the present embodiment, in addition to Component A and Component B, other preparations may be further contained as long as the effects of the present invention are not impaired. For example, from the viewpoint of increasing the above-described charge amount, a charge control agent, a lubricant, an antistatic agent, a surfactant, a plasticizer, etc. can be cited. In addition, an antioxidant, a neutralizing agent, a light stabilizer, an ultraviolet absorber, etc. can also be contained.

[0104] Through the step of collecting and forming into a sheet the fibers obtained by the method for manufacturing the fiber of the present embodiment, a nonwoven fabric can be suitably manufactured. For example, the resin mixed melt discharged from the front end of the nozzle is cooled and stretched while being collected in the collecting part to be stacked into a sheet, whereby a nonwoven fabric can be formed. From the viewpoint of improving the collectability, the above-described collecting part preferably has a collecting electrode and a high-voltage generating device connected to the collecting electrode. The collecting electrode and the high-voltage generating device in the collecting part can also serve as the above-described charged electrode and high-voltage generating device, or can be provided separately from them.

[0105] In the method for manufacturing the nonwoven fabric of the present embodiment, as described above, ultrafine fibers can be manufactured uniformly, efficiently, and at high speed from the resin mixed melt of Component A and Component B. Therefore, the nonwoven fabric of the present invention with a larger area can be efficiently manufactured industrially using an actual production line.

[0106] Examples

[0107] Hereinafter, the present invention will be described in further detail based on examples, but the present invention is not limited to such interpretation. In addition, in this embodiment, "parts" and "%" are based on mass unless otherwise specified. In Table 1, "←" means the same content as the column on the left, and "-" means that there is no value corresponding to this item. The details of the compounds described in Table 1 are shown in Table 2.

[0108] (Examples 1 to 3)

[0109] Component A was set as PCL and component B was set as glyceryl behenate, and they were mixed in the proportions shown in Table 1 to prepare a thermoplastic resin composition. A molten liquid of this thermoplastic resin composition was prepared, and using one nozzle, fiber specimens of Examples 1 to 3 were prepared by melt electrospinning. In addition, while spinning, the above-mentioned fibers were stacked to prepare non-woven fabric specimens of Examples 1 to 3 (grammage 5 g / m 2 ). The average fiber diameter of this non-woven fabric specimen was 2 μm. In the above melt electrospinning method, the applied voltage was -10 kV. In addition, a heating fluid at 180 °C was sprayed onto the molten thermoplastic resin composition discharged from the above nozzle for stretching. The fiber specimens of Examples 1 and 2 Figure 1 As shown, it has a structure in which the core layer of component A is coated with the skin layer of component B.

[0110] (Examples 4 and 5)

[0111] Using the compounds shown in Tables 1 and 2 as component B, and otherwise operating in the same manner as in Example 1, fiber specimens and non-woven fabric specimens of Examples 3 and 4 were prepared.

[0112] (Comparative Example 1)

[0113] Except for not using component B, operating in the same manner as in Example 1, fiber specimens and non-woven fabric specimens of Comparative Example 1 were prepared.

[0114] (Comparative Example 2)

[0115] Except for setting the content ratio of component B to 5% by mass, operating in the same manner as in Example 1, fiber specimens and non-woven fabric specimens of Comparative Example 2 were prepared. In the fiber specimen of Comparative Example 2, no structure in which component B was disposed on the fiber surface was found.

[0116] (Comparative Example 3)

[0117] Except for using the compounds shown in Tables 1 and 2 instead of component B, operating in the same manner as in Example 1, fiber specimens and non-woven fabric specimens of Comparative Example 3 were prepared.

[0118] (Comparative Example 4)

[0119] Except for using the compounds shown in Tables 1 and 2 to replace Component B, the same operations as in Example 1 were carried out to attempt to fabricate the fiber specimens and non-woven fabric specimens of Comparative Example 4. However, smoking occurred during the spinning process, so fiber specimens and non-woven fabric specimens could not be obtained.

[0120] (Comparative Example 5)

[0121] Component A was set as the compounds in Tables 1 and 2, and fibers were fabricated in the same manner as in Example 1 using only Component A. Component B was heated and melted, and when it became liquid, the fibers of Component A were impregnated to fabricate the fiber specimens and non-woven fabric specimens of Comparative Example 5.

[0122] (Comparative Example 6)

[0123] Except for using the compounds shown in Tables 1 and 2 to replace Component B, the same operations as in Example 1 were carried out to fabricate the fiber specimens and non-woven fabric specimens of Comparative Example 6.

[0124] For each of the above Examples and Comparative Examples, the wetting tension and the contact angle of Component B were measured. They were measured based on the above (Test Method for Wetting Tension of Fibers) and (Method for Measuring Contact Angle of Component B). In addition, for the maintenance of hydrophilicity in water, it was measured based on the following (Method for Confirming the Maintenance of Hydrophilic Properties of Fibers).

[0125] (Method for Confirming the Maintenance of Hydrophilic Properties of Fibers)

[0126] In an environmental area at a temperature of 23 °C and a relative humidity (RH) of 50%, 50 mL of deionized water was added to a 100 mL beaker, 0.5 g of fibers was taken out, and it was left standing in the deionized water for 24 hours. After that, the fibers were taken out, clamped with filter paper, and a load of 2 kg was applied for 10 minutes to fully remove the deionized water. To further remove the deionized water from the fibers, vacuum drying was carried out. Specifically, it was dried at a temperature of 40 °C and a pressure of -0.04 MPa for 24 hours. After that, a wetting tension test was carried out on the fibers in the same manner as the above (Test Method for Wetting Tension of Fibers) to confirm whether it was the same value as before being stored in deionized water. When the change value was 0, it was judged that the hydrophilic property was maintained. When the change value was greater than 0, it was judged that the hydrophilic property decreased.

[0127] (Change value) = (Wetting test liquid value (surface tension) before storage in water) - (Wetting test liquid value (surface tension) after storage in water)

[0128] [Table 1]

[0129]

[0130] [Table 2]

[0131] Compound Manufacturer Product Number Polycaprolactone Ingevity Corp. Capa 6250 Polypropylene Lyondellbasell Industries N.V. Metocene MF650Y Glyceryl behenate Sun Chemical Corporation SUNSOFT No.8100-CK Polyglyceryl-10 pentastearate Sun Chemical Corporation SUNSOFT Q-185S-C Glyceryl myristate Sun Chemical Corporation NIKKOL MGM Glyceryl monoisostearate Sun Chemical Corporation NIKKOL MGIS Glyceryl octanoate Sun Chemical Corporation SUNSOFT No.760-C Sucrose stearate Mitsubishi Chemical Corporation RYOTO Sugar Ester S-1170

[0132] As shown in Table 1, compared with Comparative Example 1 in which the content ratio of Component B is 5%, in Examples 1 to 5, the wetting tension of the fiber after spinning is all 73 mN / m or more, and the hydrophilicity is sufficient. That is, it was confirmed that the wetting tension test liquid penetrated into the material up to 73 mN / m. In addition, compared with Comparative Example 3 in which the compound used in place of Component B is liquid, the maintainability of the hydrophilicity in water in Examples 1 to 5 did not change before water immersion. Compared with Comparative Example 4 in which the number of carbon atoms of the compound used in place of Component B is less than 14, fiber specimens were successfully obtained in Examples 1 to 5. Compared with Comparative Example 5 in which polypropylene is used in place of Component A and Component B is added later, the wetting tension test liquid penetrated up to 73 mN / m in Examples 1 to 5, and the maintainability of the hydrophilicity in water also did not change before water immersion.

[0133] The present invention has been described in connection with its embodiments and examples, but unless otherwise specified, the present invention is not limited by any of the detailed descriptions, and should be broadly interpreted without departing from the inventive concept and scope shown in the claims.

[0134] This application claims priority based on Japanese Patent Application No. 2022-189676 filed in Japan on November 28, 2022, and this is hereby incorporated by reference and made part of the description of this specification.

[0135] Symbol Explanation

[0136] 1 Fiber

[0137] 2 Core layer of Component A

[0138] 3 Skin layer of Component B.

Claims

1. A fiber, characterized in that: Based on the mass of the whole fiber, it contains 50% by mass or more of the following component A and 10% by mass or more of the following component B, and component A and component B are contained inside the fiber. Component A: aliphatic polyester; Component B: an ester compound of a polyol and a fatty acid, which is water-insoluble, has a solidification point of 30°C or higher, and contains a fatty acid group having 14 or more and less than 24 carbon atoms.

2. The fiber according to claim 1, characterized in that: The wetting tension test value of the fiber is 73 mN / m or more.

3. The fiber according to claim 1 or 2, characterized in that: Component B contains a compound having a contact angle of water measured in the form of a plate of 46° or less.

4. The fiber according to any one of claims 1 to 3, characterized in that: Component A contains a biodegradable compound.

5. The fiber according to claim 4, characterized in that: The biodegradability means that the biodegradation degree of the polyester measured according to JIS K 6953-1 is 30% or more.

6. The fiber according to any one of claims 1 to 5, characterized in that: Component A contains one or more selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene adipate succinate, and polydioxanone.

7. The fiber according to claim 6, characterized in that: Component A contains polycaprolactone.

8. The fiber according to any one of claims 1 to 7, characterized in that: A part of component B is disposed on the fiber surface.

9. The fiber according to any one of claims 1 to 8, characterized in that: The content ratio 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, more preferably 75% by mass or more and 85% by mass or less, based on the mass of the whole fiber.

10. The fiber according to any one of claims 1 to 9, characterized in that: The ratio of the number of fatty acid groups to the number of hydroxyl groups in component B (fatty acid group / hydroxyl group) is 0.6 or less.

11. The fiber according to any one of claims 1 to 10, characterized in that: Component B contains a compound having no repeating unit in the fatty acid group.

12. The fiber according to any one of claims 1 to 11, characterized in that: The fatty acid group of the compound contained in component B is a saturated fatty acid group, and preferably the saturated fatty acid group is a straight-chain saturated fatty acid.

13. The fiber according to any one of claims 1 to 12, characterized in that: The molecular weight of the hydrophilic group of the compound contained in component B is 100 g / mol or less.

14. The fiber according to any one of claims 1 to 13, characterized in that: The content ratio of component B is 11% by mass or more and 40% by mass or less, preferably 15% by mass or more and 30% by mass or less, more preferably 18% by mass or more and 25% by mass or less, based on the mass of the whole fiber.

15. The fiber according to any one of claims 1 to 14, characterized in that: The solidification point of the compound contained in the component B is 40°C or higher and 100°C or lower, preferably 50°C or higher and 90°C or lower, more preferably 70°C or higher and 80°C or lower.

16. The fiber according to any one of claims 1 to 15, characterized in that: The number of carbon atoms of the fatty acid group of the compound contained in the component B is 16 or more and 23 or less, preferably 18 or more and 22 or less, more preferably 20 or more and 22 or less.

17. The fiber according to any one of claims 1 to 16, characterized in that: The component B contains a compound having a contact angle of water measured in a plate shape of 9.2° or more and 45.9° or less.

18. The fiber according to any one of claims 1 to 17, characterized in that: The component B contains one or more selected from glycerol fatty acid ester compounds and polyglycerol fatty acid ester compounds.

19. The fiber according to any one of claims 1 to 18, characterized in that: The component B contains one or more selected from glyceryl behenate, polyglycerol pentastearate, and glyceryl myristate, and preferably contains glyceryl behenate.

20. The fiber according to any one of claims 1 to 19, characterized in that: The fiber diameter of the fiber is 0.1 μm or more and 5 μm or less.

21. The fiber according to any one of claims 1 to 19, characterized in that: The fiber diameter of the fiber is 0.5 μm or more and 2.5 μm or less.

22. A non-woven fabric, characterized in that: It contains the fiber according to any one of claims 1 to 21.

23. The non-woven fabric according to claim 22, characterized in that: The average fiber diameter of the non-woven fabric is 0.1 μm or more and 5 μm or less.

24. The non-woven fabric according to claim 22, characterized in that: The average fiber diameter of the non-woven fabric is 0.5 μm or more and 2.5 μm or less.

25. A fiber product, characterized in that: It contains the fiber according to any one of claims 1 to 21, or the non-woven fabric according to any one of claims 22 to 24.

26. The fiber product according to claim 25, characterized in that: The fiber product is a skin care sheet.

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