Fiber for artificial hair, fiber bundle for artificial hair, and hair decorative product

Abstract

According to the present invention, it is possible to provide a fiber for artificial hair and a fiber bundle for artificial hair excellent in volume, and a hair decorating product using the same.SOLUTION: According to the present invention, there is provided a fiber for artificial hair, wherein the fiber for artificial hair includes a hollow portion extending in a longitudinal direction of the fiber for artificial hair, the fiber for artificial hair is composed of a resin composition containing a vinyl chloride resin and a resin A, the resin A contains at least one of an acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition contains 0.5 to 10 parts by mass of the resin A with respect to 100 parts by mass of the vinyl chloride resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an artificial hair fiber, an artificial hair fiber bundle, and a hair accessory product. [Background technology]

[0002] Artificial hair is becoming increasingly important as an alternative to human hair in hair accessories such as wigs, hair accessories, hair bands, doll hair, etc. Materials for artificial hair fibers include acrylic resins, vinyl chloride resins, and polyester resins, and artificial hair fibers made from these resins are commercially available.

[0003] Patent Document 1 discloses artificial hair containing hollow fibers with a hollow portion having a hollow ratio of 10 to 50%. Patent Document 2 also discloses artificial hair fibers having a void in the center of the fiber cross section, the ratio of the area of ​​the void to the total area of ​​the fiber cross section being 5% to 50%, the cross-sectional shape of the fiber cross section being flattened multi-lobed, and the void having first and second sides inclined at an angle of 70 to 110 degrees relative to the major axis of the fiber cross section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-285772 [Patent Document 2] WO2014 / 196642 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for lightweight artificial hair fibers, and for example, Patent Documents 1 and 2 disclose artificial hair fibers having hollow portions. However, conventional artificial hair fibers have the problem that they sometimes lack sufficient volume.

[0006] The present invention has been made in view of the above circumstances, and provides artificial hair fibers and fiber bundles for artificial hair that are excellent in volume, as well as hair accessory products using these. [Means for solving the problem]

[0007] According to the present invention, there is provided a fiber for artificial hair, the fiber for artificial hair having a hollow portion extending in the longitudinal direction of the fiber for artificial hair, the fiber for artificial hair being composed of a resin composition containing a vinyl chloride resin and resin A, the resin A containing at least one of an acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition containing 0.5 to 10 parts by mass of resin A per 100 parts by mass of the vinyl chloride resin.

[0008] Various embodiments of the present invention will be described below as examples, and the embodiments shown below can be combined with each other. [1] A fiber for artificial hair, the fiber for artificial hair having a hollow portion extending in the longitudinal direction of the fiber for artificial hair, the fiber for artificial hair being composed of a resin composition containing a vinyl chloride resin and a resin A, the resin A containing at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, the resin composition containing 0.5 to 10 parts by mass of the resin A per 100 parts by mass of the vinyl chloride resin. [2] An artificial hair fiber, the artificial hair fiber having a hollow portion extending in the longitudinal direction of the artificial hair fiber, the artificial hair fiber being composed of a resin composition containing a vinyl chloride resin and a resin A, the resin A containing at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, the resin composition being heated at 200°C at a shear rate of 1.2 × 10 4 Artificial hair fiber with a melt viscosity of 96 to 118 Pa·sec measured with a capillary rheometer at 1 / sec. [3] The fiber for artificial hair according to [1] or [2], wherein the resin A has a weight-average molecular weight of 50,000 to 15,000,000. [4] The artificial hair fiber according to any one of [1] to [3], wherein the hollow portion occupies 5 to 55% of the area of ​​the cross section perpendicular to the longitudinal direction of the artificial hair fiber. [5] An artificial hair fiber bundle comprising the artificial hair fiber according to any one of [1] to [4], wherein the standard deviation of A / B is 0.15 or less, where A is the major axis of the outer surface in a cross section perpendicular to the longitudinal direction of the artificial hair fiber and B is the minor axis. [6] A hair accessory product comprising the artificial hair fiber according to any one of [1] to [4] or the artificial hair fiber bundle according to [5]. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide artificial hair fibers and fiber bundles for artificial hair that have excellent volume, as well as hair accessory products using them. The artificial hair fibers and fiber bundles for artificial hair according to one embodiment of the present invention have excellent volume, and therefore have a larger volume per unit mass than other products, making it possible to create a desired voluminous hairstyle with a small amount of attachment, enabling the realization of a wide range of hairstyles, causing less damage to one's own hair and scalp, and reducing waste and environmental impact. [Brief explanation of the drawings]

[0010] [Figure 1] Figure 1 shows schematic diagrams of the nozzle openings used in the melt spinning process of artificial hair fibers according to Examples and Comparative Examples. Figure 1A shows a schematic diagram of the nozzle opening used in Example 1, etc. Figure 1B shows a schematic diagram of the nozzle opening used in Example 4, etc. Figure 1C shows a schematic diagram of the nozzle opening used in Example 5, etc. [Figure 2] FIG. 2 is a photograph of the cross section of the artificial hair fibers according to Example 1, Example 3, and Comparative Example 3, observed with a laser microscope. [Figure 3] FIG. 3 is a schematic cross-sectional view of an artificial hair fiber according to one embodiment of the present invention, showing a circular cross-section. [Figure 4] FIG. 4 is a schematic cross-sectional view of an artificial hair fiber according to one embodiment of the present invention, showing an elliptical cross-section. [Figure 5] FIG. 5 is a cross-sectional schematic diagram of an artificial hair fiber according to one embodiment of the present invention, showing a multi-lobe cross-section in which multiple C-shaped fibers are joined together. [Figure 6] FIG. 6 is a cross-sectional view of an artificial hair fiber according to one embodiment of the present invention, showing cross sections of a substantially triangular shape and a substantially rectangular shape. [Figure 7] FIG. 7 is a cross-sectional view of a fiber for artificial hair according to one embodiment of the present invention, illustrating the major and minor diameters. [Figure 8] FIG. 8 is a schematic diagram of the opening surface of a nozzle used in the melt spinning process of artificial hair fiber according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below by illustrating embodiments of the present invention. The present invention is not limited by these descriptions. The features of the embodiments of the present invention described below can be combined with each other. Furthermore, each feature can be an invention independently. Any number of "0"s (for example, one or two) may be added to the end of the numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0012] 1. First perspective 1.1 Artificial hair fibers An artificial hair fiber according to one embodiment of the present invention has a hollow portion extending in the longitudinal direction of the artificial hair fiber. The artificial hair fiber according to one embodiment of the present invention is composed of a resin composition containing a vinyl chloride resin and a resin A, where the resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition contains 0.5 to 10 parts by mass of the resin A per 100 parts by mass of the vinyl chloride resin.

[0013] 1.1.1 Shape of artificial hair fibers An artificial hair fiber according to one embodiment of the present invention has a hollow portion extending in the longitudinal direction of the artificial hair fiber. The hollow portion can be continuous for 10 cm or more in the longitudinal direction of the fiber for artificial hair. The fiber bundle for artificial hair according to the present invention is lightweight due to the hollow portion, and offers many advantages, such as the ability to create a desired voluminous hairstyle with a small amount of attachment, the ability to achieve a wide range of hairstyles including heavy long styles, the ability to reduce damage to one's own hair and scalp, and the ability to reduce waste and environmental impact.

[0014] The artificial hair fiber according to one embodiment of the present invention has one or more hollow portions, and may have two or more hollow portions. The number of hollow portions may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, or may be within a range between any two of the numbers exemplified here. The artificial hair fiber according to one embodiment of the present invention can have one hollow portion.

[0015] The cross-sectional shape perpendicular to the longitudinal direction of an artificial hair fiber according to one embodiment of the present invention will be described with reference to the drawings. The cross-sectional shape perpendicular to the longitudinal direction of an artificial hair fiber according to one embodiment of the present invention can be any one selected from a circular shape (Fig. 3), an elliptical shape (Fig. 4), a multi-lobed shape formed by joining two or more C-shaped portions (Fig. 5), and an approximately polygonal shape such as an approximately triangular shape or an approximately rectangular shape (Fig. 6).

[0016] Although the method for producing the artificial hair fiber according to the present invention is not particularly limited, the artificial hair fiber is generally obtained by melt-spinning a resin composition. Furthermore, the artificial hair fiber having a hollow portion is formed by melt-extrusion from a nozzle having a single C-shaped nozzle hole or a nozzle having multiple holes, as shown in FIG. 1 of Patent Document 1, for example. Here, the resin composition is at least partially fragmented while passing through the nozzle, but after being discharged from the nozzle hole, the resin composition comes into contact with each other and fuses, forming a hollow portion.

[0017] The cross-sectional shape of an artificial hair fiber according to one embodiment of the present invention will be described in more detail below with reference to Figure 3. An artificial hair fiber 100 according to one embodiment of the present invention has a hollow portion 15 and a solid portion surrounded by an inner surface 12 and an outer surface 11. An artificial hair fiber according to one embodiment of the present invention can have a joint surface 14 (shown by dashed lines in Figures 3A to 3F) where resin compositions are fused together during the melt extrusion process. Furthermore, the joint surface 13, which is the region including the joint surface 14, may have at least one of an inner protrusion 16 that protrudes toward the hollow portion 15 and an outer protrusion 17 that protrudes toward the outside of the artificial hair fiber. 3A shows a circular cross section with neither inner protrusions 16 nor outer protrusions 17, FIG. 3B shows a circular cross section with only inner protrusions 16, FIG. 3C shows a cross section with only outer protrusions 17, and FIG. 3D shows a circular cross section with inner protrusions 16 and outer protrusions 17. 3E shows a circular cross section having two joining surfaces 14 and two joining portions 13, each having an inner protrusion 16 and an outer protrusion 17. FIG. 3F shows a circular cross section having three joining surfaces 14 and three joining portions 13, each having only an inner protrusion 16.

[0018] While FIG. 3 shows a case where the fiber cross section is circular, the number of bonding surfaces 14 and bonding portions 13 can each be any number greater than or equal to one, even when the fiber cross section has another shape. The number of bonding surfaces 14 and bonding portions 13 can be, for example, 1, 2, 3, 4, 5, 6, 7, or 8, and may be within a range between any two of the numbers exemplified here. Even when the hollow portion 15 has another shape, the bonding portion can be provided with at least one of an inner protrusion 16 protruding toward the hollow portion 15 and an outer protrusion 17 protruding toward the outside of the artificial hair fiber. By providing a protrusion to thicken the bonding portion 13 and increasing the area of ​​the bonding surface 14 where the resin compositions are fused together, the bonding strength can be improved. Details of the manufacturing method will be described later. Since the artificial hair fiber according to the present invention is made from a resin composition with a specific blend, the fiber itself has higher strength than conventional artificial hair fibers with a hollow portion. Therefore, the artificial hair fiber according to one embodiment of the present invention does not need to have a protrusion. Having a protrusion can be defined as a protrusion height of 1 μm or more, and the protrusion height can be defined as the distance from the tangent at the intersection of a virtual inner surface (outer surface) obtained by extending the inner surface 12 (or outer surface 11) other than the protrusion assuming that there is no protrusion, and a straight line extending in the direction of the protrusion through the center of the protrusion, to the apex of the protrusion.

[0019] In another embodiment, FIG. 4A shows an elliptical cross section with one joint 13 and no inner or outer protrusions 16 or 17, and FIG. 4B shows an elliptical cross section with one joint 13 and only the inner protrusion 16. Figure 5A shows a bilobal cross section with two joints 13 and no inner or outer protrusions 16 or 17, Figure 5B shows a bilobal cross section with two joints 13 and only inner protrusions 16, and Figure 5A shows a trilobal cross section with three joints 13 and only inner protrusions 16. FIG. 6A shows a roughly triangular cross section with three joints 13 and no inner protrusions 16 or outer protrusions 17, and FIG. 6B shows a roughly triangular cross section with three joints 13 and only inner protrusions 16. FIG. 7A shows a substantially rectangular cross section having four joints 13 and no inner protrusions 16 or outer protrusions 17, and FIG. 6B shows a substantially rectangular cross section having four joints 13 and only inner protrusions 16.

[0020] In an artificial hair fiber according to one embodiment of the present invention, the hollow ratio is defined as the area ratio of hollow portions 15 in a cross section perpendicular to the longitudinal direction of the artificial hair fiber, and is preferably 5 to 55%, more preferably 9 to 50%, and even more preferably 10 to 50%. The hollow ratio may be, for example, 5, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55%, and may be within a range between any two of the values ​​exemplified here.

[0021] The hollow ratio can be calculated using the following formula. Hollow ratio = (area enclosed by the inner surface 12) / (area enclosed by the outer surface 11) × 100 The area enclosed by the outer surface 11 means the cross-sectional area when it is assumed that the artificial hair fiber does not have a hollow portion. The hollowness can be determined by cutting the artificial hair fiber perpendicular to the longitudinal direction, observing the cut surface with a laser microscope or scanning electron microscope, and performing image analysis; specifically, it can be determined by the method described in the Examples. The hollowness can be calculated as the average value obtained by observing multiple locations, for example, the average value of 30 locations. By setting the hollowness at or above the lower limit, the advantages of having hollow portions can be more reliably obtained. If the hollowness exceeds the upper limit, it is undesirable because it leads to a decrease in structure retention, increased rigidity due to an increase in fiber diameter, and a deterioration in touch.

[0022] The artificial hair fiber according to one embodiment of the present invention can have a major diameter A of 30 to 300 μm in a cross section perpendicular to the longitudinal direction of the artificial hair fiber. The major diameter A is, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 μm, and may be within a range between any two of the values ​​exemplified here.

[0023] The ratio of major axis A to minor axis B (A / B), which is the ratio of major axis A to minor axis B in a cross section perpendicular to the longitudinal direction of the artificial hair fiber according to one embodiment of the present invention, can be 1.0 to 4.5. A / B is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, or 4.5, and may be within a range between any two of the values ​​exemplified here. By setting the major axis / minor axis (A / B) within the above numerical range (particularly by setting it to be equal to or less than the upper limit), for example, when pressure is applied to the fiber, the force is applied uniformly, the fiber structure is less likely to break, and the hollow shape is more likely to be maintained. The major axis, minor axis, and major axis / minor axis (A / B) can be average values ​​obtained by observing multiple locations, for example, 30 locations.

[0024] When the major axis of the outer surface of the cross section perpendicular to the longitudinal direction of the artificial hair fiber according to one embodiment of the present invention is A and the minor axis is B, the standard deviation of A / B is preferably 0.15 or less. The standard deviation of A / B may be, for example, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, or 0.15, and may be within a range between any two of the values ​​exemplified here. When the standard deviation of A / B is within the above numerical range, the volume of the artificial hair fiber is further improved. When the standard deviation of A / B is within the above numerical range, there is little variation in the cross-sectional shape of the artificial hair fiber, many fibers maintain the shape as originally designed, and few fibers are crushed or deformed, which is thought to contribute to maintaining volume. The standard deviation of A / B can be calculated from, for example, measurements at 30 locations.

[0025] In this specification, the major and minor diameters can be determined by cutting the fiber perpendicular to the longitudinal direction, observing the cut surface with a laser microscope or scanning electron microscope, and performing image analysis. The major diameter is the largest distance between two parallel lines on the same plane when a cross section of the artificial hair fiber perpendicular to the longitudinal direction is sandwiched. The minor diameter is the distance between the intersection of the outer surface 11 and a line passing through the midpoint of the major diameter and perpendicular to the major diameter. Examples of major and minor diameters are shown in Figure 7. Figure 7A shows the major and minor diameters of an elliptical cross section, Figure 7B shows the major and minor diameters of a bilobal cross section, and Figure 7C shows the major and minor diameters of a trilobal cross section. The cross-sectional shape of the fiber can be controlled by the composition of the resin composition, the conditions for melt extrusion in the spinning process, and the shape of the nozzle used for melt extrusion. The standard deviation of A / B can be controlled, in particular, by adjusting the composition of the resin composition (the type and amount of each component, and the melt viscosity).

[0026] 1.1.2 Composition of artificial hair fibers An artificial hair fiber according to one embodiment of the present invention is composed of a resin composition containing a vinyl chloride resin and resin A. In the artificial hair fiber according to the first aspect, resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition contains 0.5 to 10 parts by mass of resin A per 100 parts by mass of the vinyl chloride resin.

[0027] A vinyl chloride resin according to one embodiment of the present invention may comprise a vinyl chloride polymer containing monomer units (vinyl chloride monomer units) derived from vinyl chloride monomer. The vinyl chloride resin according to the present invention may comprise a homopolymer obtained by homopolymerizing vinyl chloride monomer and / or a copolymer containing monomer units derived from vinyl chloride monomer and another monomer copolymerizable with vinyl chloride monomer. Examples of copolymers include copolymers of vinyl chloride and vinyl esters, such as vinyl chloride-vinyl acetate copolymer and vinyl chloride-vinyl propionate copolymer; copolymers of vinyl chloride and olefins, such as vinyl chloride-ethylene copolymer and vinyl chloride-propylene copolymer; and vinyl chloride-acrylonitrile copolymer. Furthermore, the vinyl chloride resin according to the present invention may consist of one type of vinyl chloride polymer or may contain two or more types of vinyl chloride polymers.

[0028] Resin A may contain at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and may contain at least one of a polymer containing a (meth)acrylic monomer unit, a polymer containing a vinyl cyanide monomer unit, and a polymer containing a styrene monomer unit. Resin A preferably contains at least one of a polymer containing a (meth)acrylic monomer unit, and a polymer containing a vinyl cyanide monomer unit and a styrene monomer unit. The resin composition may contain one or more resins A.

[0029] Examples of (meth)acrylic monomer units include units derived from (meth)acrylic monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, normal propyl acrylate, normal propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, normal butyl acrylate, normal butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, secondary butyl acrylate, secondary butyl methacrylate, tertiary butyl acrylate, tertiary butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. The term "(meth)acrylic monomer unit" refers to an acrylic monomer unit and a methacrylic monomer unit. These may be used alone or in combination of two or more.

[0030] Examples of vinyl cyanide monomer units include units derived from acrylonitrile, methacrylonitrile, etc., with acrylonitrile being preferred. These may be used alone or in combination of two or more.

[0031] Examples of the styrene-based monomer unit include units derived from styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, α-methylstyrene, and α-methyl-p-methylstyrene, with styrene being preferred. These may be used alone or in combination of two or more.

[0032] When Resin A is taken as 100% by mass, the total content of (meth)acrylic monomer units, vinyl cyanide monomer units, and styrene monomer units contained in Resin A is preferably 50% by mass or more. The total content of (meth)acrylic monomer units, vinyl cyanide monomer units, and styrene monomer units is, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. When Resin A is taken as 100% by mass, the content of (meth)acrylic monomer units contained in Resin A is, for example, 0, 10, 20, 30, 40, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. Resin A may be composed of (meth)acrylic monomer units. When Resin A is taken as 100% by mass, the total content of vinyl cyanide-based monomer units and styrene-based monomer units contained in Resin A is, for example, 0, 10, 20, 30, 40, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, and may be within a range between any two of the values ​​exemplified here. Resin A may be composed of vinyl cyanide-based monomer units and styrene-based monomer units.

[0033] Resin A preferably has a weight-average molecular weight of 50,000 to 15,000,000, and more preferably 200,000 to 10,000,000. The weight-average molecular weight may be, for example, 50,000, 100,000, 200,000, 500,000, 1,000,000, 2,000,000, 3,000,000, 4,000,000, 5,000,000, 6,000,000, 7,000,000, 8,000,000, 9,000,000, 10,000,000, 11,000,000, 12,000,000, 13,000,000, 14,000,000, or 15,000,000, and may be within a range between any two of the values ​​exemplified here. When the weight-average molecular weight of Resin A is within the above range, the melt viscosity of the resin composition can be more appropriately adjusted, the fiber shape can be more fully maintained, and better spinnability can be maintained.

[0034] A resin composition according to one embodiment of the present invention contains 0.5 to 10 parts by mass of resin A relative to 100 parts by mass of vinyl chloride resin. The content of resin A relative to 100 parts by mass of vinyl chloride resin is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here. By setting the content of resin A within the above range, it is possible to obtain artificial hair fibers with excellent volume. More specifically, with conventional artificial hair fibers having a hollow portion, even if a fiber having a hollow portion can be produced in the melt spinning process, the hollow portion may be crushed or broken in subsequent processes, and the designed volume may not be obtained. According to one embodiment of the present invention, by using a specific blending ratio for the resin composition constituting the artificial hair fiber, the melt viscosity and melt tension of the resin composition are adjusted and the strength of the obtained fiber is improved, so that it is presumed that crushing and breakage of the fiber can be reduced, the fiber shape can be sufficiently maintained, and good spinnability can be maintained.

[0035] The resin composition according to one embodiment of the present invention may contain other resins in addition to the vinyl chloride resin and resin A. Examples of other resins in addition to the vinyl chloride resin and resin A include polyamide resins, polyester resins, PP resins, PET resins, PE resins, and PLA resins (polylactic acid resins).

[0036] A resin composition according to one embodiment of the present invention may contain a total of 50 to 100 mass% of vinyl chloride resin and resin A relative to 100 mass% of the resin components contained in the resin composition. The total content of vinyl chloride resin and resin A relative to 100 mass% of the resin composition may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or 100 mass%, and may be within a range between any two of the numerical values ​​exemplified here.

[0037] A resin composition according to one embodiment of the present invention may contain 50 to 100% by mass of a resin component relative to 100% by mass of the resin composition. The content of the resin component may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or 100% by mass, and may be within a range between any two of the values ​​exemplified here.

[0038] The resin composition according to one embodiment of the present invention may contain other components as needed, such as antistatic agents, heat stabilizers, lubricants, colorants, processing aids, plasticizers, reinforcing agents, UV absorbers, antioxidants, fillers, flame retardants, pigments, initial color improvers, conductivity imparting agents, and fragrances.

[0039] The resin composition according to one embodiment of the present invention has a shear rate of 1.2×10 at 200° C. 4 The melt viscosity measured with a capillary rheometer at 1 / sec is preferably 96 to 118 Pa·sec. The melt viscosity may be, for example, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, or 118 Pa·sec, or may be within a range between any two of the values ​​exemplified here. The melt viscosity can be measured specifically by the method described in the Examples. The melt viscosity of the resin composition constituting the artificial hair fiber can also be measured by melting the artificial hair fiber. The melt viscosity can be controlled particularly by adjusting the composition of the resin composition (the type and amount of each component, and the melt viscosity).

[0040] 1.3 Manufacturing method for artificial hair fibers The method for producing fibers for artificial hair according to this embodiment includes a resin composition preparation step and a spinning step, and may further include a drawing step, a heat treatment step, and a gear processing step.

[0041] 1.3.1 Resin composition preparation process In the resin composition preparation step, a resin composition can be obtained by mixing raw materials containing resin components including at least a vinyl chloride resin and resin A. Here, the raw materials contain the resin components and may contain other components as necessary.

[0042] The mixing method is not particularly limited, and conventionally known methods can be employed. For example, a powdered resin composition (powder compound) can be obtained using known mixing devices such as a Henschel mixer, super mixer, or ribbon blender, and the powder compound can then be melt-mixed to obtain a pellet-shaped resin composition (pellet compound). The powder compound can be produced by either hot blending or cold blending. For example, to reduce volatiles from the resin composition, hot blending can be performed at a cut temperature of 105 to 155°C during mixing. The pellet compound can be produced by a method similar to that used to produce pellet compounds of general vinyl chloride resins. For example, pellet compounds can be produced using kneaders such as a single-screw extruder, counter-rotating twin-screw extruder, conical twin-screw extruder, co-rotating twin-screw extruder, co-kneader, planetary gear extruder, or roll kneader. The conditions for producing the pellet compound are not particularly limited, but it is preferable to set the resin temperature to 185°C or less to prevent thermal degradation of the resin composition. A mesh can also be installed near the tip of the screw to remove small amounts of metal chips from the screw and fibers from protective gloves that may be mixed into the pellet compound. The cold-cut method can be used to manufacture pellets. A means of removing chips (fine particles generated during pellet production) that may be mixed in during cold cutting can also be used. Furthermore, since the cutter blades can chip over long periods of use, making chips more likely to be generated, it is recommended that they be replaced as needed.

[0043] 1.3.2 Spinning process In the spinning step, the resin composition is melt-spun to obtain fibers for artificial hair. As an example, the resin composition (e.g., pellet compound) can be extruded from a heated cylinder through a nozzle to perform melt spinning. Any conventionally known extruder can be used, such as a single-screw extruder, a counter-rotating twin-screw extruder, or a conical twin-screw extruder.

[0044] The melt spinning conditions can be appropriately set depending on the type of resin composition so that the resin melts and hollow portions are formed. For example, the cylinder temperature can be set to 150 to 190°C, and the nozzle temperature can be set to 155 to 195°C. The extrusion speed is preferably 5 to 20 kg / h, and more preferably 8 to 18 kg / h. When the temperature and extrusion speed are within these ranges, hollow portions are easily formed and have a suitable size.

[0045] The undrawn yarn melt-spun from the nozzle is introduced into a heating cylinder (for example, heating cylinder temperature 250°C) and instantaneously heat-treated, and can be taken up by a take-up machine installed directly below the nozzle (for example, about 4.5 m away).

[0046] The resin composition according to one embodiment of the present invention preferably has excellent melt spinnability, and in the melt spinning process, the number of thread breakages occurring before an undrawn thread is produced is preferably four or less times per hour, more preferably less than one time.

[0047] The nozzle for melt extrusion of the artificial hair fiber according to one embodiment of the present invention can be appropriately selected depending on the shape and hollowness of the artificial hair fiber to be obtained. Due to the presence of the separation portions 23 between the nozzle holes, at least a portion of the resin composition is divided during melt extrusion, but after being discharged from the nozzle holes, the resin composition comes into contact with each other and fuses, forming a hollow portion. Furthermore, in one embodiment of the present invention, the resin composition discharged from the nozzle holes can expand due to the die swelling effect, forming inner protrusions 16 and / or outer protrusions 17.

[0048] As an example, when producing artificial hair fibers having a circular cross section, as shown in Figure 3F, with three bonding surfaces 14 and three bonding portions 13, each of which has only an inner protrusion 16, a nozzle having an opening surface as shown in Figure 1A can be used. The shape of the nozzle hole 200 will be described with reference to Fig. 1A. The nozzle opening surface has three openings, and each opening surface has a nozzle hole outer surface 21 and a nozzle hole inner surface 22. The three openings are spaced apart by spacing portions 23.

[0049] The opening can have at least one of a nozzle hole inner protrusion 24 and a nozzle hole outer protrusion 25. The nozzle hole inner protrusion 24 can contribute to the formation of the inner protrusion 16 in the artificial hair fiber, and the nozzle hole outer protrusion 25 can contribute to the formation of the outer protrusion 17. By providing the nozzle hole inner protrusion 24 and the nozzle hole outer protrusion 25, the bonding surface in the artificial hair fiber can be further increased. Figure 1A shows only the nozzle hole inner protrusion 24.

[0050] It should be noted that the nozzle hole inner protrusion 24 and the nozzle hole outer protrusion 25 are not essential for forming the protrusions on the cross section of the artificial hair fiber. After the resin composition is extruded from the nozzle hole, it may expand due to the die swell effect, which is thought to result in the formation of a joint (protrusion) with an increased area of ​​the joint surface, and protrusions may be formed even if the nozzle does not have the nozzle hole inner protrusion 24 and the nozzle hole outer protrusion 25 on the nozzle opening surface.

[0051] Several embodiments of the nozzle hole are shown in Figure 8. The nozzle hole shown in Figure 8A has two separating portions 23 and a nozzle hole inward protrusion 24. The nozzle hole shown in Figure 8A makes it possible to produce artificial hair fibers having an elliptical cross section, as shown in Figure 4A, which have two bonding surfaces 14 and two bonding portions 13, and each bonding portion 13 has only an inward protrusion 16. The nozzle hole shown in Fig. 8B has two separating portions 23 and a nozzle hole outward protrusion 25. The nozzle hole shown in Fig. 8B allows the production of artificial hair fibers having two bonding surfaces 14 and two bonding portions 13, each of which has only an outward protrusion 17 and has an elliptical cross section. The nozzle hole shown in Fig. 8C has two separation portions 23, a nozzle hole inner protrusion 24, and a nozzle hole outer protrusion 25. The nozzle hole shown in Fig. 8C allows the production of artificial hair fibers having two bonding surfaces 14 and two bonding portions 13, each of which has an elliptical cross section with an inner protrusion 16 and an outer protrusion 17. The nozzle preferably has a nozzle hole capable of ejecting a plurality of fibers simultaneously.

[0052] 1.3.4 Stretching and heat treatment processes The method for producing an artificial hair fiber according to one embodiment of the present invention may include a drawing step and a heat treatment step. In the drawing step, the undrawn artificial hair fiber obtained in the melt spinning step is drawn in a drawing machine to obtain drawn artificial hair fiber. As an example, in the drawing step, the undrawn artificial hair fiber can be drawn 2 to 5 times in an air atmosphere at 90 to 110°C. In the heat treatment step, the stretched artificial hair fiber can be heat-treated using a heat treatment machine. As an example, in the heat treatment step, the stretched artificial hair fiber is heat-treated in an air atmosphere at 90 to 110°C so that the stretched artificial hair fiber is 0.5 to 3.0 times its original size, causing heat shrinkage of the entire fiber length, thereby obtaining a heat-treated artificial hair fiber with the desired fineness.

[0053] 1.3.5 Gear machining process The method for producing artificial hair fibers according to this embodiment may also include a gear processing step. In the gear processing step, crimping can be performed by passing the fiber bundle between two meshing high-temperature gears. The material of the gears used in the gear processing step, the shape of the gear waves, and the number of gears are not particularly limited. In the gear processing step, the shape of the resulting artificial hair fiber can be controlled by appropriately adjusting the depth of the gear wave grooves, the gear surface temperature, the processing speed, and the pressure conditions between the gears, taking into consideration the fiber material and fineness. These processing conditions are not particularly limited, but as an example, the depth of the gear wave grooves can be 0.2 to 6 mm, preferably 0.5 to 5 mm, the gear surface temperature can be 30 to 100°C, preferably 40 to 80°C, and the processing speed can be 0.5 to 10 m / min, preferably 1.0 to 8.0 m / min.

[0054] The method for producing artificial hair fibers according to one embodiment of the present invention may include other steps, for example, a surface treatment agent application step.

[0055] In the present invention, the term "artificial hair fiber" includes artificial hair fiber after spinning, and encompasses artificial hair fiber before the drawing step, after the drawing step, before the heat treatment step, after the heat treatment step, before the gear processing step, and after the gear processing step. The artificial hair fiber according to the present invention can sufficiently maintain its structure even after a step following the melt spinning step (for example, a drawing step), so it may be artificial hair fiber after a drawing step, for example.

[0056] 1.4 Artificial hair fiber bundle The artificial hair fiber bundle according to the present invention contains the above-mentioned artificial hair fiber.

[0057] In an artificial hair fiber bundle according to one embodiment of the present invention, the average hollowness of the artificial hair fibers contained in the artificial hair fiber bundle is preferably 5 to 55%, more preferably 9 to 50%, and even more preferably 10 to 50%. The average hollowness may be, for example, 5, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55%, and may be within a range between any two of the values ​​exemplified here. The average hollowness can be determined by averaging the value obtained by observing a plurality of fibers, for example, by averaging the value obtained by observing 30 fibers. The definition of the hollow ratio, the method of measurement, and the relationship with the effects are as described above.

[0058] In an artificial hair fiber bundle according to one embodiment of the present invention, when the major axis of the outer surface in a cross section perpendicular to the longitudinal direction of the artificial hair fibers contained in the artificial hair fiber bundle is A and the minor axis is B, the ratio of the major axis A to the minor axis B, i.e., major axis / minor axis (A / B), can have an average value of 1.0 to 4.5. The average value of A / B is, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, or 4.5, and may be within a range between any two of the values ​​exemplified here.

[0059] In an artificial hair fiber bundle according to one embodiment of the present invention, when the major axis of the outer surface of the cross section perpendicular to the longitudinal direction of the artificial hair fibers contained in the artificial hair fiber bundle is A and the minor axis is B, it is preferable that the standard deviation of A / B is 0.15 or less. Specifically, the standard deviation of A / B obtained by observing the cut surfaces of 30 fibers using a laser microscope, scanning electron microscope, or the like and analyzing the images is preferably 0.15 or less. The standard deviation of A / B may be, for example, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, or 0.15, or may be within a range between any two of the values ​​exemplified here. The definitions, measurement methods, and relationship to effects of A / B and A / B standard deviation are as described above.

[0060] In the artificial hair fiber bundle according to one embodiment of the present invention, when the cross sections of 30 fibers are observed at a magnification of 400 times using a laser microscope, it is preferable that 5 or less fibers are crushed. Here, "crushed fibers" can be fibers in which the major axis / minor axis (A / B) ratio in the obtained fiber cross section is 1.2 times or more the designed major axis / minor axis (A / B) ratio assumed from the nozzle design. In the artificial hair fiber bundle according to one embodiment of the present invention, when the cross sections of 30 fibers are observed, the number of crushed fibers may be, for example, 1, 2, 3, 4, or 5, and may be within a range between any two of the numerical values ​​exemplified here.

[0061] In an artificial hair fiber bundle according to one embodiment of the present invention, the structural retention rate of the cross section of the artificial hair fiber is preferably 90% or more. The structural retention rate is, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100%, and may be within a range between any two of the values ​​exemplified here. Specifically, the structural retention rate can be calculated using the method described in the Examples, and can be calculated, for example, using the following formula based on the observation results of fiber cross sections with an N number of 300. Structure retention rate=(300-ij) / 300 i: Number of fibers with one or more hollow parts that are not entirely covered by solid parts j: Number of fibers whose hollow parts are crushed and whose inner surfaces come into contact with each other "Fibers having hollow portions that are not entirely covered by solid portions" refers to a state in which, for example, when a fiber has a circular cross section, the cross section is not doughnut-shaped but has one or more C-shapes, etc., with some portions separated.

[0062] The artificial hair fiber bundle according to one embodiment of the present invention preferably has a volume (specific volume) of 5 cc / g or more, more preferably 8.5 cc / g or more. The volume may be, for example, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8 ... 1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0 cc / g, and may be within a range between any two of the numerical values ​​exemplified here.

[0063] In one embodiment of the present invention, the artificial hair fiber bundle may contain fibers other than the above-mentioned artificial hair fibers, and may contain hollow artificial hair fibers and / or solid artificial hair fibers other than the above-mentioned artificial hair fibers. The artificial hair fiber bundle according to the present invention can have a content of the above-mentioned artificial hair fibers of 50% by mass or more, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, when the artificial hair fibers contained in the artificial hair fiber bundle are taken as 100% by mass, and may also be within a range between any two of the numerical values ​​exemplified here. The artificial hair fiber bundle according to one embodiment of the present invention may be made of the above-mentioned artificial hair fiber.

[0064] 1.5 Hair accessories The artificial hair fiber and / or artificial hair fiber bundle according to one embodiment of the present invention can be used in hair accessory products. A hair accessory product according to one embodiment of the present invention comprises the above-mentioned artificial hair fiber and / or artificial hair fiber bundle. Examples of hair accessories include wigs, hair pieces, braids, hair extensions, doll hair, hair wigs, false hair, and hair bands. The hair accessory product according to one embodiment of the present invention provides many benefits, such as excellent volume and the ability to create the desired voluminous hairstyle with a small amount of application, the ability to achieve a wide range of hairstyles including heavy long styles, reduced damage to one's own hair and scalp, and reduced waste and environmental impact. The hair accessory product according to one embodiment of the present invention having the above-mentioned features can be applied to various styles, but is particularly suitable for braids including braids and twists.

[0065] 2. Second perspective 2.1 Artificial Hair Fibers An artificial hair fiber according to one embodiment of the present invention has a hollow portion extending in the longitudinal direction of the artificial hair fiber, and the artificial hair fiber is made of a resin composition containing a vinyl chloride resin and resin A, and resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition is heated at 200°C and a shear rate of 1.2 × 10 4 The melt viscosity measured with a capillary rheometer is 96 to 118 Pa·sec at 1 / sec. The following will mainly explain the differences from the first viewpoint.

[0066] 2.1.1 Shape of artificial hair fibers The shape of the artificial hair fiber according to the second aspect can be the same as that of the first aspect.

[0067] 2.1.2 Composition of artificial hair fibers The artificial hair fiber according to one embodiment of the present invention is composed of a resin composition containing a vinyl chloride resin and a resin A, and the resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, and the resin composition is heated at 200°C and a shear rate of 1.2 × 10 4 The melt viscosity measured with a capillary rheometer is 96 to 118 Pa·sec at 1 / sec.

[0068] The types of vinyl chloride resin and resin A, the types of monomer units contained in resin A, their respective contents, and molecular weights can be the same as those in the first aspect.

[0069] The resin composition according to one embodiment of the present invention has a shear rate of 1.2×10 at 200° C. 4 The melt viscosity measured with a capillary rheometer at 1 / sec is 96 to 118 Pa sec. The melt viscosity may be, for example, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, or 118 Pa sec, or may be within a range between any two of the values ​​exemplified here. The melt viscosity can be measured specifically by the method described in the Examples. The melt viscosity of the resin composition constituting the artificial hair fiber can also be measured by melting the artificial hair fiber. The melt viscosity can be controlled particularly by adjusting the composition of the resin composition (the type and amount of each component, and the melt viscosity). According to one embodiment of the present invention, by adjusting the resin composition constituting the artificial hair fiber to have a specific melt viscosity, the melt tension is adjusted and the strength of the resulting fiber is improved, which is thought to reduce crushing and breakage of the fiber, allow the fiber shape to be sufficiently maintained, and maintain good spinnability.

[0070] The resin composition according to one embodiment of the present invention is not particularly limited in the content of each component as long as it satisfies the above melt viscosity, but may contain 0.5 to 10 parts by mass of resin A relative to 100 parts by mass of vinyl chloride resin. The content of resin A relative to 100 parts by mass of vinyl chloride resin is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 parts by mass, and may be within a range between any two of the values ​​exemplified here. By setting the content of resin A within the above numerical range, the melt viscosity of the resin composition can be more appropriately adjusted, the shape of the fiber can be sufficiently maintained, and good spinnability can be maintained.

[0071] The resin composition according to one embodiment of the present invention may contain other resins in addition to the vinyl chloride resin and resin A. Examples of other resins in addition to the vinyl chloride resin and resin A include polyamide resins, polyester resins, PP resins, PET resins, PE resins, and PLA resins (polylactic acid resins).

[0072] A resin composition according to one embodiment of the present invention may contain a total of 50 to 100 mass% of vinyl chloride resin and resin A relative to 100 mass% of the resin components contained in the resin composition. The total content of vinyl chloride resin and resin A relative to 100 mass% of the resin composition may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or 100 mass%, and may be within a range between any two of the numerical values ​​exemplified here.

[0073] A resin composition according to one embodiment of the present invention may contain 50 to 100% by mass of a resin component relative to 100% by mass of the resin composition. The content of the resin component may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or 100% by mass, and may be within a range between any two of the values ​​exemplified here.

[0074] The resin composition according to one embodiment of the present invention may contain other components as needed, such as antistatic agents, heat stabilizers, lubricants, colorants, processing aids, plasticizers, reinforcing agents, UV absorbers, antioxidants, fillers, flame retardants, pigments, initial color improvers, conductivity imparting agents, and fragrances.

[0075] 2.3 Manufacturing method for artificial hair fibers, artificial hair fiber bundles, hair accessory products The method for producing artificial hair fibers, the artificial hair fiber bundle, and the hair accessory product can be the same as in the first aspect. [Example]

[0076] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

[0077] Example 1 <Spinning process> 100 parts by weight of a vinyl chloride resin (manufactured by Taiyo PVC Co., Ltd., product name: TH1000), 10 parts by weight of Mitsubishi Chemical Corporation's Metablen (weight average molecular weight 5,000,000) as resin A, 5 parts by weight of additives such as plasticizers, stabilizers, and lubricants (specifically, 3 parts by weight of a stabilizer composition, 1 part by weight of epoxidized soybean oil, 0.4 parts by weight of a phosphorus-based chelating agent, and 0.6 parts by weight of polyethylene wax), and 0.5 parts by weight of carbon black were mixed in a blender. The blended materials were kneaded using a φ40 mm single-screw extruder to obtain a resin composition in the form of pellets for spinning. The resulting resin composition in the form of pellets was spun in a φ40 mm single-screw melt spinning machine using a nozzle with an opening as shown in the schematic diagram of Figure 1.

[0078] The stabilizer composition used to obtain the resin composition had the following components and composition: Hydrotalcite compound (Mg4Al2(OH)12CO3·3H2O) 72.6 parts by mass Zinc stearate 13.1 parts by mass Silica ("Carplex (registered trademark) #80" manufactured by DSL Japan Co., Ltd.) 2.2 parts by mass Dibenzoylmethane 2.3 parts by mass Dipentaerythritol 0.9 parts by mass Vinyl chloride resin (manufactured by Taiyo PVC Co., Ltd., product name: TH1000) 8.9 parts by mass

[0079] Other additives used to obtain the resin composition are as follows: Epoxidized soybean oil: ADEKA Cizer (registered trademark) O-130P, manufactured by ADEKA Corporation Phosphorus chelating agent: ADEKA CORPORATION, ADK STAB (registered trademark) 1030 Polyethylene wax: Mitsui Chemicals, Inc.

[0080] <Stretching process and heat treatment process> The obtained undrawn yarn (artificial hair fiber before drawing process) was drawn at 100°C at a draw ratio of 3, and then placed in a heat treatment device and subjected to a heat treatment process at 115°C to obtain artificial hair fiber after the heat treatment process. The relaxation rate during the heat treatment was 0.50 to 0.99 times.

[0081] (Examples 2 to 11, Comparative Examples 1 and 2) Artificial hair fibers were produced in the same manner as in Example 1, except that the type and amount of resin A and the shape of the nozzle used for melt spinning were changed as shown in the table.

[0082] The resin A used in each of the examples and comparative examples is shown below. Resin A-1 Mw: 100,000: alkyl methacrylate-alkyl acrylate copolymer Resin A-2 Mw: 200,000: Mitsubishi Chemical Corporation, P-570A, alkyl methacrylate copolymer Resin A-3 Mw: 5 million: Mitsubishi Chemical Corporation, P-531A, alkyl methacrylate-alkyl acrylate copolymer Resin A-4 Mw: 10 million: Mitsubishi Chemical Corporation, P-1500, acrylonitrile-styrene copolymer Resin A-5 MW: 11 million: alkyl methacrylate-alkyl acrylate copolymer

[0083] <Observation of fiber cross section> First, artificial hair fibers were cut to an appropriate length, and the resulting bundle was wrapped in vinyl tape. The artificial hair fiber bundle was then cut perpendicular to the longitudinal direction with a utility knife to create a cross section of the fiber. A cross section of the fiber was photographed at 400x magnification using a laser microscope. FIG. 2 shows enlarged photographs of the cross sections of the fibers for artificial hair of Example 1, Example 3, and Comparative Example 3. The artificial hair fibers obtained in each of the Examples and Comparative Examples all had the largest hollow portion approximately at the center of the fiber cross section. (Hollow rate) As in the above <Observation of fiber cross section>, the fiber cross section was photographed using a laser microscope at a magnification of 400. From the obtained image, the area ratio of hollow parts in the cross section (hollow ratio) was measured. (Hollow ratio) = {(area enclosed by the inner surface) / (area enclosed by the outer surface)} x 100 The hollow ratio was calculated using a controller VK-X150 manufactured by Keyence Corporation. The hollow ratio was the average value for an N number of 50. In all of the examples and comparative examples, hollow portions were present in all of the artificial hair fibers.

[0084] (Shape maintenance degree) As in the above <Observation of fiber cross section>, the fiber cross sections were photographed using a laser microscope at a magnification of 400. Using the obtained images, the shape retention of the cross sections of 30 fibers was evaluated according to the following evaluation criteria. ○: One or less crushed fiber, and voids are maintained △: 2 to 5 crushed fibers, and some fibers have been deformed due to crushing ×: Six or more crushed fibers, and many crushed fibers Note that "crushed fibers" refer to fibers in which the ratio of major axis / minor axis in the obtained fiber cross section is 1.2 times or more the ratio expected from the nozzle design. For the nozzles in Figures 1A and 1B, the ratio expected from the nozzle design is 1, and for the nozzle in Figure 1C, the ratio expected from the nozzle design is 1.3.

[0085] (major diameter / minor diameter and their standard deviation) As in the above <Observation of fiber cross section>, the fiber cross section was photographed at 400x magnification using a laser microscope. From the obtained image, the major axis and inner diameter were measured, and the major axis / minor axis ratio was calculated. The major axis / minor axis ratio was taken as the average value of n=30. The standard deviation was also calculated.

[0086] (melt viscosity) The pellet-shaped resin composition used in each example was subjected to shear rate of 1.2 × 10°C using a capillary rheometer (Toyo Seiki Seisakusho Co., Ltd., Capillograph 1D, capillary length: 30 mm, capillary diameter: 2.0 mm) with a barrel temperature set to 200°C. 4 The viscosity was measured when the material was extruded at a rate of 1 / sec. The melt viscosity was measured at a constant shear rate and the value when the melt viscosity stabilized was recorded as the measured value.

[0087] (Structure retention rate) As in the above <Observation of fiber cross section>, the fiber cross section was photographed at a magnification of 400x using a laser microscope. From the obtained images, the structure retention rate was calculated based on the following formula with an N number of 300. The structure retention rate was calculated using the following formula. Structure retention rate=(300-ij) / 300 i: Number of fibers with one or more hollow parts that are not entirely covered by solid parts j: Number of fibers whose hollow parts are crushed and whose inner surfaces come into contact with each other Note that "fibers having hollow parts that are not entirely covered by solid parts" refers to a state in which, for example, when a fiber has a circular cross section, the cross section is not doughnut-shaped but C-shaped, with some parts separated.

[0088] (volume) A 120 g bundle of artificial hair fibers was prepared using artificial hair fibers cut to a length of 120 cm, and the bundle was folded back to a length of 60 cm and placed in a 39.5 mm wide partition. The height of the sample was then measured, and the specific volume was calculated using the following formula: Divider width × sample length × sample height ÷ fiber mass = specific volume (cc / g)

[0089] (Spinnability) In the melt spinning process, the occurrence of yarn breakage was visually observed until an undrawn yarn was produced, and evaluated according to the following criteria. ○: Less than one thread breakage per hour (no thread breakage occurs within an hour) △: Thread breakage occurs 1 to 4 times per hour ×: Thread breakage occurs 5 times or more per hour

[0090] [Table 1] [Explanation of symbols]

[0091] 100 Cross section of artificial hair fiber 11 Exterior 12 Inner 13 Joint 14 Joint surface 15 Hollow part 16 Inner protrusion 17 Outer protrusion 200 nozzle holes 21 Nozzle hole outer surface 22 Inner surface of nozzle hole 23 Separation part 24 Nozzle hole inner protrusion 25 nozzle hole outer protrusion

Claims

1. An artificial hair fiber, The artificial hair fiber has a hollow portion extending in the longitudinal direction of the artificial hair fiber, The artificial hair fiber is composed of a resin composition containing a vinyl chloride resin and a resin A, The resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, The resin composition contains 0.5 to 10 parts by mass of the resin A relative to 100 parts by mass of the vinyl chloride resin.

2. An artificial hair fiber, The artificial hair fiber has a hollow portion extending in the longitudinal direction of the artificial hair fiber, The artificial hair fiber is composed of a resin composition containing a vinyl chloride resin and a resin A, The resin A contains at least one of a (meth)acrylic monomer unit, a vinyl cyanide monomer unit, and a styrene monomer unit, The resin composition was subjected to a shear stress test at 200°C and a shear rate of 1.2 × 10 ４ A fiber for artificial hair, having a melt viscosity of 96 to 118 Pa·sec as measured by a capillary rheometer at 1 / sec.

3. The artificial hair fiber according to claim 1 or 2, wherein the resin A has a weight average molecular weight of 50,000 to 15,000,000.

4. 3. The artificial hair fiber according to claim 1, wherein the hollow portion occupies 5 to 55% of the area of ​​a cross section perpendicular to the longitudinal direction of the artificial hair fiber.

5. An artificial hair fiber bundle comprising the artificial hair fiber according to claim 1 or 2, An artificial hair fiber bundle, wherein the standard deviation of A / B is 0.15 or less, when the major axis of the outer surface in a cross section perpendicular to the longitudinal direction of the artificial hair fiber is A and the minor axis is B.

6. A hair accessory product comprising the artificial hair fiber according to claim 1 or 2.

Images