Fiber for artificial hair, hair decoration product, and nozzle for melt extrusion of fiber for artificial hair

Abstract

Provided is a fiber which is for artificial hair, has a hollow part, and has a highly-maintained structure. According to the present invention, provided is a fiber for artificial hair, the fiber comprising a hollow part extending in the longitudinal direction of the fiber for artificial hair, wherein the cross section perpendicular to the longitudinal direction of the fiber for artificial hair is provided with at least one joining part, and the joining part has a strength enhancing structure for enhancing the joining strength.

Description

Nozzles for melt extrusion of artificial hair fibers, hair decoration products and artificial hair fibers

[0001] The present invention relates to artificial hair fibers, hair decoration products and nozzles for melt extrusion of artificial hair fibers.

[0002] Artificial hair is becoming increasingly important as an alternative to human hair in head accessories such as wigs, hairpieces, hair extensions, hair bands, doll hair, etc. Materials used to make 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 having hollow portions with a hollow ratio of 10 to 50%. Patent Document 2 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.

[0004] JP 2008-285772 A

[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, with artificial hair fibers having hollow portions, there are cases where the formed hollow portion structure is partially separated or collapsed, making it impossible to maintain the structure.

[0006] The present invention has been made in view of these circumstances and provides an artificial hair fiber having a hollow portion, the structure of which is highly maintained. According to the artificial hair fiber of one embodiment of the present invention, the hollow portion structure is not destroyed and is maintained with high accuracy even after undergoing processes such as drawing and heat treatment. According to one embodiment of the present invention, a hair accessory product including the artificial hair fiber is provided. Furthermore, according to one embodiment of the present invention, a nozzle for melt extrusion of the artificial hair fiber, which can produce the artificial hair fiber, is provided.

[0007] According to the present invention, there is provided an artificial hair fiber comprising a polyvinyl chloride resin and a chlorinated polyvinyl chloride resin, wherein the artificial hair fiber has a hollow portion extending in the longitudinal direction of the artificial hair fiber, and a cross section perpendicular to the longitudinal direction of the artificial hair fiber has at least one joint, and the joint has a strength-enhancing structure for improving the bonding strength.

[0008] After extensive research, the inventors discovered that artificial hair fibers having a hollow portion can be made into artificial hair fibers in which the hollow structure is highly maintained by providing a strength-enhancing structure in the cross section to improve the bonding strength, and this led to the completion of the present invention.

[0009] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [1] An artificial hair fiber, the artificial hair fiber having a hollow portion extending in the longitudinal direction of the artificial hair fiber, a cross section perpendicular to the longitudinal direction of the artificial hair fiber having at least one joint portion, the joint portion having a strength-reinforcing structure for improving the joint strength. [2] The artificial hair fiber according to [1], in which the strength-reinforcing structure is thicker than other portions to improve the joint strength. [3] The artificial hair fiber according to [1] or [2], in which the strength-reinforcing structure has at least one of an inner protrusion protruding toward the hollow portion and an outer protrusion protruding toward the outside of the artificial hair fiber. [4] An artificial hair fiber, the artificial hair fiber having a hollow portion extending in the longitudinal direction of the artificial hair fiber, and a cross section perpendicular to the longitudinal direction of the artificial hair fiber having at least one of an inner protrusion protruding toward the hollow portion and an outer protrusion protruding toward the outside of the artificial hair fiber. [5] An artificial hair fiber according to any of [1] to [4], wherein the hollow portion occupies 5 to 50% of the area of ​​the cross section perpendicular to the longitudinal direction of the artificial hair fiber. [6] The maximum thickness X of the central portions of the inner protrusion and the outer protrusion is X ＭＡＸ , where Y is the thickness of the thinnest portion other than the inner protrusion and the outer protrusion, X ＭＡＸThe artificial hair fiber according to any one of [1] to [5], wherein Y / Y is 0.90 to 2.50. [7] The artificial hair fiber according to any one of [1] to [6], which contains a vinyl chloride resin. [8] A hair accessory product comprising the artificial hair fiber according to any one of [1] to [7]. [9] A nozzle for melt extrusion of the artificial hair fiber according to any one of [1] to [8], the nozzle having one or more C-shaped nozzle holes or two or more rod-shaped nozzle holes.

[10] The nozzle according to [9], wherein, in the nozzle opening surface, the minor axis length of the nozzle hole is A and the length of the line connecting the points at which the inner surface of the nozzle hole and the outer surface of the nozzle hole are equidistant is B, and B / A is 3 to 20.

[11] The nozzle according to [9] or

[10] , wherein, in the nozzle opening surface, the minor axis length of the nozzle hole is A and the distance between the nozzle holes is C, and C / A is 0.5 to 1.5.

[0010] The artificial hair fiber according to the present invention is a fiber for artificial hair having a hollow portion, and the hollow structure is maintained without being partially separated or crushed. According to the artificial hair fiber of one embodiment of the present invention, the hollow structure is not destroyed even after processes such as drawing and heat treatment, and is stably maintained with high accuracy. According to one embodiment of the present invention, a hair accessory product is provided that includes the artificial hair fiber, which is lightweight and has an increased volume per unit weight compared to other products, allowing the desired voluminous hairstyle to be achieved with a small amount of application, enabling a wide range of hairstyles to be achieved, causing less damage to one's own hair and scalp, and reducing waste and environmental impact. Furthermore, according to one embodiment of the present invention, a nozzle for melt extrusion of the artificial hair fiber is provided, which can produce the artificial hair fiber.

[0011] Fig. 1 is a cross-sectional schematic diagram of an artificial hair fiber having an inner protrusion and a shape in which two C-shaped members are joined together, with Fig. 1A showing each component, Fig. 1B showing the major axis 18, the thickness X of the protrusion at the center, the thickness Y of the thin portion, and Fig. 1C showing the height Z of the protrusion. Fig. 2 is a cross-sectional schematic diagram of an artificial hair fiber having an inner protrusion and an outer protrusion and a shape in which two C-shaped members are joined together, with Fig. 2A showing each component, Fig. 2B showing the thickness X of the protrusion at the center, the thickness Y of the thin portion, and Fig. 2C showing the height Z of the protrusion. Fig. 3 is a cross-sectional schematic diagram of an artificial hair fiber having an outer protrusion and a shape in which two C-shaped members are joined together, with Fig. 3A showing each component, Fig. 3B showing the thickness X of the protrusion at the center, the thickness Y of the thin portion, and Fig. 3C showing the height Z of the protrusion. Fig. 4 is a cross-sectional schematic diagram of an artificial hair fiber having no protrusion and a shape in which two C-shaped members are joined together, which corresponds to a comparative example of the present invention. Fig. 5 is a cross-sectional schematic diagram of an artificial hair fiber having an inner protrusion and a shape in which three C-shaped portions are joined together, with Fig. 5A showing each component, Fig. 5B showing the thickness X of the center of the protrusion and the thickness Y of the thin portion, and Fig. 5C showing the height Z of the protrusion. Fig. 6 is a cross-sectional schematic diagram of an artificial hair fiber having no protrusions and a shape in which three C-shaped portions are joined together, which corresponds to a comparative example of the present invention. Fig. 7 is a cross-sectional schematic diagram of a circular artificial hair fiber having inner and outer protrusions, with Fig. 7A showing each component, Fig. 7B showing the thickness X of the center of the protrusion and the thickness Y of the thin portion, and Fig. 7C showing the height Z of the protrusion. Fig. 8 is a cross-sectional schematic diagram of a circular artificial hair fiber having no protrusions, which corresponds to a comparative example of the present invention. Fig. 9 is a cross-sectional schematic diagram of an artificial hair fiber having an approximately triangular shape and an inner protrusion, with Fig. 9A showing each component, and Fig. 9B showing the thickness X of the center of the protrusion, the thickness Y of the thin portion, and the height Z of the protrusion. Fig. 10 is a cross-sectional schematic diagram of a substantially triangular artificial hair fiber without protrusions, which corresponds to a comparative example of the present invention. Fig. 11 is a cross-sectional schematic diagram of a substantially rectangular artificial hair fiber with inner protrusions, Fig. 11A shows each component, and Fig. 11B shows the thickness X of the center of the protrusion, the thickness Y of the thin portion, and the protrusion height Z. Fig. 12 is a cross-sectional schematic diagram of a substantially rectangular artificial hair fiber without protrusions, which corresponds to a comparative example of the present invention. Fig. 13 is a schematic diagram of the opening surface of a nozzle having two C-shaped nozzle holes. Fig. 13A is a schematic diagram of the opening surface of a nozzle having two C-shaped nozzle holes, without nozzle hole inner protrusions or nozzle hole outer protrusions.Fig. 13B is a schematic diagram of the opening surface of a nozzle having two C-shaped nozzle holes and a nozzle hole outward protrusion. Fig. 13C is a schematic diagram of the opening surface of a nozzle having two C-shaped nozzle holes and a nozzle hole inward protrusion. Fig. 13D is a schematic diagram of the opening surface of a nozzle having two C-shaped nozzle holes and a nozzle hole outward protrusion and a nozzle hole inward protrusion. Fig. 14 is a schematic diagram of the opening surface of a nozzle having three C-shaped nozzle holes. Fig. 14A is a schematic diagram of the opening surface of a nozzle having three C-shaped nozzle holes and no nozzle hole inward protrusion and no nozzle hole outward protrusion. Fig. 14B is a schematic diagram of the opening surface of a nozzle having three C-shaped nozzle holes and a nozzle hole inward protrusion. Fig. 15 is a schematic diagram of the opening surface of a nozzle having four C-shaped nozzle holes. Fig. 16 is a schematic diagram of the opening surface of a nozzle having three rod-shaped nozzle holes. Fig. 16A is a schematic diagram of the opening surface of a nozzle having three rod-shaped nozzle holes and no nozzle hole inward protrusions or nozzle hole outward protrusions. Fig. 14B is a schematic diagram of the opening surface of a nozzle having three rod-shaped nozzle holes and a nozzle hole inward protrusion. Fig. 17 is a schematic diagram of the opening surface of a nozzle having four rod-shaped nozzle holes. Fig. 18 is a laser microscope photograph of the cross section of the artificial hair fiber according to Example 2. Fig. 19 is a laser microscope photograph of the cross section of the artificial hair fiber according to Example 5. Fig. 20 is a laser microscope photograph of the cross section of the artificial hair fiber according to Example 12. Fig. 21a is a laser microscope photograph of the cross section of the artificial hair fiber according to Comparative Example 1, and Fig. 21b is a laser microscope photograph of the cross section of the artificial hair fiber according to Comparative Example 2.

[0012] 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.

[0013] 1. First Aspect 1.1 Artificial Hair Fiber 1.1.1 Shape The 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 a cross section perpendicular to the longitudinal direction of the artificial hair fiber has at least one joint portion, and the joint portion has a strength-enhancing structure for improving the bonding strength.

[0014] The artificial hair fiber according to the present invention has a hollow portion extending in the longitudinal direction of the artificial hair fiber. In the present invention, the hollow portion can be continuous for 10 cm or more in the longitudinal direction of the artificial hair fiber. The artificial hair fiber 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 wear, 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.

[0015] The cross section perpendicular to the longitudinal direction of the artificial hair fiber according to one embodiment of the present invention can be a circle (Figs. 7A to 7C), an ellipse, a bilobal shape with two C-shaped members joined together (Figs. 1A to 1C, 2A to 2C, 3A to 3C), a trilobal shape with three C-shaped members joined together (Figs. 5A to 5C), a quadrilobal shape with four or more C-shaped members joined together, an approximately triangular shape (Figs. 9A to 9B), an approximately rectangular shape (Figs. 11A to 11C), or an approximately polygonal shape.

[0016] The artificial hair fiber according to one embodiment of the present invention can have a major diameter 18 of 30 to 300 μm in a cross section perpendicular to the longitudinal direction of the artificial hair fiber. The major diameter may be, 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, or may be within a range between any two of the values ​​exemplified here.

[0017] In a cross section perpendicular to the longitudinal direction of the artificial hair fiber, the hollow portions 15 can occupy 5 to 50% of the area. The area ratio of the hollow portions 15 is, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50%, and may be within a range between any two of the values ​​exemplified here. The area ratio of the hollow portions 15 can be calculated using the following formula: Area ratio of hollow portions 15 = (area surrounded by the inner surface 12) / (area surrounded by the outer surface 11) × 100. The area surrounded by the outer surface 11 refers to the cross-sectional area assuming that the artificial hair fiber does not have hollow portions. The area ratio of hollow portions can be calculated by cutting the artificial hair fiber perpendicular to the longitudinal direction, observing the cut surface with a laser microscope or scanning electron microscope, and analyzing the images; specifically, it can be calculated using the method described in the examples. By setting the area ratio of hollow portions within the above numerical range, the benefits of having hollow portions can be more reliably obtained. If the hollow ratio exceeds 50%, the increased fiber diameter leads to increased rigidity and a worsening of the feel, which is not preferable.

[0018] An artificial hair fiber according to one embodiment of the present invention includes at least one joint 13, which is equipped with a nozzle for improving bonding strength. Artificial hair fibers are generally obtained by melt-spinning a resin composition for artificial hair fibers. Furthermore, artificial hair fibers having a hollow portion are 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. In the present invention, the portion including the bonding surface 14 (shown by dashed lines in FIGS. 1A, 2A, 3A, 5A, 7A, 9A, 11A, etc.) where the resin composition is fused to each other during the melt-extrusion process is referred to as the joint 13.

[0019] The artificial hair fiber according to one embodiment of the present invention has a cross section perpendicular to the longitudinal direction of the artificial hair fiber that has at least one bonded portion 13. The number of bonded portions 13 can be one or more, preferably two or more, and can also be three or more. The number of bonded portions 13 can be, for example, one, two, three, four, or five, or may be within a range between any two of the values ​​exemplified here.

[0020] The joint 13 according to one embodiment of the present invention includes a bond strength reinforcing structure 19 for improving the bond strength. The bond strength reinforcing structure is not particularly limited as long as it is a structure that enhances the bond strength of the joint 13. As an example, the bond strength reinforcing structure can improve the bond strength by making the joint 13 thicker than other portions. That is, by making the joint thicker and increasing the area of ​​the bonded surface 14 where the resin compositions are fused together, the bond strength can be improved. As described above, the joint is the location where the resin compositions that were separated during passage through the nozzle are fused together. In artificial hair fibers produced by conventional technology, the joint is potentially the weakest point, and can be the starting point for separation or collapse of parts of the structure during, for example, the drawing process, the heat treatment process, the processing process for undrawn artificial hair fibers, and the subsequent process of clamping the heat-treated fibers between heated gears to impart a corrugated shape. The artificial hair fiber according to one embodiment of the present invention can reduce the probability of separation and breakage of the bond starting points by improving the strength of the points that could be the starting points of structural breakdown, and can stably maintain the hollow structure of the artificial hair fiber with high accuracy. The artificial hair fiber according to one embodiment of the present invention has at least one bond 13 equipped with a bond strength reinforcing structure 19 for improving the bond strength.

[0021] The strength-enhancing structure according to one embodiment of the present invention may have at least one of inner protrusions 16 protruding toward the hollow portion 15 and outer protrusions 17 protruding toward the outside of the artificial hair fiber. The bonding strength-enhancing structure 19 may have inner protrusions 16 and outer protrusions 17 as shown in Figures 2A and 7A, or may have either inner protrusions 16 or outer protrusions 17, or may have only outer protrusions 17 as shown in Figure 3A, preferably having at least inner protrusions 16, or may have only inner protrusions 16 as shown in Figures 1A, 5A, 9A, and 11A. From the perspective of improving the feel of the artificial hair fiber, it is preferable that the outer protrusions are small in size and frequency, and it is preferable that the outer protrusions 17 are smaller or less frequent than the inner protrusions 16, and it is more preferable that only inner protrusions 16 are present.

[0022] The maximum value of the thickness X at the center of the inner protrusion 16 and the outer protrusion 17 in a cross section perpendicular to the longitudinal direction of the artificial hair fiber according to one embodiment of the present invention is X ＭＡＸ , when the thickness of the thinnest portion other than the inner protrusion and the outer protrusion is Y, X ＭＡＸ / Y can be 0.90 to 2.50, preferably 1.00 to 2.50, and more preferably 1.05 to 2.50. ＭＡＸ / Y may be, for example, 0.90, 0.95, 1.00, 1.05, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 2.10, 2.20, 2.30, 2.40, or 2.50, or may be within a range between any two of the values ​​exemplified here.

[0023] The thickness X of the center of the inner protrusion 16 and the outer protrusion 17 can be the thickness when crossing the center of the protrusion in the direction of the protrusion. When the cross section perpendicular to the longitudinal direction of the artificial hair fiber has multiple protrusions, X ＭＡＸcan be the maximum value of multiple X's. A thicker thickness at the center means that the area of ​​the joint surface 14 is wider. The thickness Y of the thinnest part other than the inner protrusion 16 and the outer protrusion 17 can be the shortest distance between the outer surface 11 and the inner surface 12 at the part other than the inner protrusion 16 and the outer protrusion 17. The thickness Y of the thinnest part can be the thickness at the part farthest from any joint. When there is one joint 13, the thickness Y of the thinnest part can be the thickness at the part facing the joint. When there are two or more joints 13, the thickness Y of the thinnest part can be the thickness at the midpoint between adjacent joints. X ＭＡＸ By setting / Y to the above lower limit or more, sufficient strength can be imparted to the joint 13. In one embodiment of the present invention, when the artificial hair fiber has multiple protrusions in one cross section, it is more preferable that X / Y, calculated from the thickness X of the center of each protrusion, is within the above numerical range.

[0024] X can be 5 to 70 μm. X can be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 μm, and may be within a range between any two of the values ​​exemplified here. Y can be 5 to 40 μm. Y can be, for example, 5, 10, 15, 20, 25, 30, 35, or 40 μm, and may be within a range between any two of the values ​​exemplified here. Furthermore, the artificial hair fiber according to one embodiment of the present invention can have a thickness of 5 μm or more at its thinnest point. The thickness of the thinnest point can be, for example, 5, 10, 15, 20, 25, 30, 35, or 40 μm, and may be within a range between any two of the values ​​exemplified here. In conventional artificial hair fibers, separation and crushing of the structure may occur starting from thin portions of the fiber. However, in the artificial hair fiber according to one embodiment of the present invention, the thicknesses X and Y are within the above-mentioned numerical ranges, and / or the thickness of the thinnest portion is equal to or greater than the above-mentioned lower limit, thereby making it possible to further suppress separation and crushing of the structure.

[0025] The protrusions will be described based on a representative embodiment. Figures 7A to 7C show cross sections of an artificial hair fiber having inner protrusions 16 and outer protrusions 17 in a circular cross section perpendicular to the longitudinal direction, while Figure 8 shows a cross section of a comparative example having no protrusions. In this embodiment, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​shown here. Here, the protrusion height Z can be defined as the distance from the tangent at the intersection of a virtual inner surface (outer surface) (dashed line in Figure 7C) extending from the inner surface 12 (or outer surface 11) other than the protrusions assuming there are no protrusions, and a straight line extending in the direction of the protrusions through the center of the protrusions, to the apex of the protrusion.

[0026] When a cross section perpendicular to the longitudinal direction of an artificial hair fiber has a multi-lobed shape formed by bonding multiple C-shaped members, cross sections having inner protrusions 16 and outer protrusions 17 are shown in Figures 2A to 2C, cross sections having only inner protrusions 16 are shown in Figures 1A to 1C and 5A to 5C, cross sections having only outer protrusions 17 are shown in Figures 3A to 3C, and a cross section equivalent to a comparative example having no protrusions is shown in Figure 4. In these embodiments, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​exemplified here. Here, Z can be the distance from a tangent line passing through two points on the inner (or outer) surfaces of two adjacent C-shaped members via a protrusion to the apex of the protrusion (Figures 1C, 2C, 3C, and 5C). Figures 1, 2, 3, and 5 show cases where the cross section perpendicular to the longitudinal direction of the artificial hair fiber is a bilobal cross section formed by joining two or three C-shaped pieces, but the protrusions and their heights can also be specified in the same way when the cross section is a quadrilobular cross section or more.

[0027] 9A-9B and 11A-11B show cross sections of artificial hair fibers having only inner protrusions 16 when the cross section perpendicular to the longitudinal direction is a polygonal shape such as a substantially triangular or substantially rectangular shape, while FIGS. 10 and 12 show cross sections of comparative examples having no protrusions. In these embodiments, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​shown here. Here, Z is the distance from a line including a vertex perpendicular to the bisector of the angle of a polygon on the imaginary inner surface (outer surface) (dashed lines in FIGS. 9B and 11B) obtained by extending the inner surface 12 (or outer surface 11) other than the protrusions assuming that the protrusions are absent, to the vertex of the protrusion. Figures 9 and 11 show cases where the cross section perpendicular to the longitudinal direction of the artificial hair fiber is approximately triangular or approximately rectangular, but the protrusions and protrusion heights can be similarly specified even in cases where the cross section is pentagonal or larger.

[0028] The cross-sectional shape of the artificial hair fiber can be controlled by the composition of the resin composition for artificial hair fiber that constitutes the artificial hair fiber, the melt extrusion conditions, and the shape of the nozzle used for melt extrusion.

[0029] 1.1.2 Composition The resin composition constituting the artificial hair fiber according to one embodiment of the present invention is not particularly limited and may contain at least one of polyamide-based resins, polyester-based resins, vinyl chloride-based resins, AS-based resins (acrylonitrile-styrene-based resins), PP resins, PET resins, PE resins, PAN-based resins, and PLA-based resins (polylactic acid-based resins). The effect of defining the shape of the artificial hair fiber described above is manifested regardless of the composition of the artificial hair fiber, but the effect of the present invention is particularly useful when the resin composition constituting the artificial hair fiber has weak tackiness, making it prone to separation of joints and structural collapse. From the perspective of easily achieving these structural advantages and easily achieving the die swelling effect described below, the artificial hair fiber according to one embodiment of the present invention preferably contains a vinyl chloride-based resin. Furthermore, the artificial hair fiber according to one embodiment of the present invention preferably contains a vinyl chloride-based resin and an AS-based resin (acrylonitrile-styrene-based resin).

[0030] A polyvinyl 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 polyvinyl 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 polyvinyl 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.

[0031] The resin composition constituting the artificial hair fiber according to one embodiment of the present invention contains 50 to 99% by mass of vinyl chloride resin, preferably 65 to 95% by mass, and more preferably 65 to 90% by mass, based on 100% by mass of the resin composition. Specifically, the content may be, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99% by mass, and may be within a range between any two of the values ​​exemplified here.

[0032] AS-based resins (acrylonitrile-styrene-based resins) are copolymers containing styrene-based monomer units and acrylonitrile-based monomer units, and may contain other monomer units copolymerizable therewith, as necessary. The AS-based resins may contain, for example, 60, 65, 70, 75, 80, 85, or 90% by mass of styrene-based monomer units relative to 100% by mass of the AS resin, or may fall within a range between any two of the values ​​exemplified herein. The AS-based resins may contain, for example, 10, 15, 20, 25, 30, 35, or 40% by mass of acrylonitrile-based monomer units relative to 100% by mass of the AS resin, or may fall within a range between any two of the values ​​exemplified herein.

[0033] The artificial hair fiber according to one embodiment of the present invention may contain other ingredients as needed, such as antistatic agents, heat stabilizers, lubricants, colorants, processing aids, plasticizers, strengthening agents, UV absorbers, antioxidants, fillers, flame retardants, pigments, initial color improvers, conductivity imparting agents, and fragrances.

[0034] 1.2 Artificial Hair Fiber Bundle The artificial hair fiber bundle according to one embodiment of the present invention includes the above-mentioned artificial hair fiber. The artificial hair fiber bundle according to one embodiment of the present invention is preferably made of the above-mentioned artificial hair fiber.

[0035] <Structure Retention Rate> In the artificial hair fiber bundle according to one embodiment of the present invention, the structure retention rate of the cross section of the artificial hair fiber is preferably 90% or more. The structure 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. The structure retention rate indicates the proportion of artificial hair fibers having a cross section in which the bonded portions are not separated and the hollow portion is not collapsed, and can be calculated specifically based on the following formula using the method described in the examples: Structure retention rate = (300 - i - j) / 300, where i: number of fibers with one or more separated bonded portions, j: number of fibers in which the hollow portion is collapsed and the inner surfaces are in contact with each other.

[0036] The artificial hair fiber bundle according to one embodiment of the present invention has a high structural retention rate, and the hollow structure is maintained with high accuracy without being destroyed even after undergoing processes such as drawing and heat treatment, and the advantages of having a hollow portion can be fully and reliably obtained. As mentioned above, the structural retention rate can be increased by adjusting the cross-sectional structure of the artificial hair fiber.

[0037] <Volume> The artificial hair fiber bundle according to one embodiment of the present invention preferably has a volume of 5 cc / g. The volume may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 cc / g, or may be within a range between any two of the values ​​exemplified here.

[0038] 1.3 Method for producing artificial hair fiber The method for producing artificial hair fiber according to one embodiment of the present invention can include a step of preparing a resin composition for artificial hair fiber and a spinning step. In the spinning step, artificial hair fiber is melt-extruded using a nozzle described below to obtain artificial hair fiber having the above-mentioned structure.

[0039] 1.3.1 Preparation of Resin Composition for Artificial Hair Fiber In the preparation of a resin composition for artificial hair fiber, raw materials containing resins are mixed to obtain a resin composition for artificial hair fiber. Here, the raw materials include a base resin and may contain other components as necessary.

[0040] 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 polyvinyl chloride resins. For example, pellet compounds can be produced using kneaders such as a single-screw extruder, a counter-rotating twin-screw extruder, a conical twin-screw extruder, a co-rotating twin-screw extruder, a co-kneader, a planetary gear extruder, or a 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 produce pellets. A means of removing chips (fine particles generated during pellet production) that may be mixed in during cold cutting can also be used. Since the cutter blades can chip and generate chips easily after prolonged use, it is recommended to replace them as needed.

[0041] 1.3.2 Spinning Process In the spinning process, the resin composition for artificial hair fibers is melt-spun to obtain artificial hair fibers. As an example, the resin composition (e.g., pellet compound) can be extruded from a heated cylinder through a nozzle to melt-spin. Conventional known extruders can be used as the extruder, including, for example, a single-screw extruder, a counter-rotating twin-screw extruder, and a conical twin-screw extruder. The nozzle for melt extrusion will be described later.

[0042] The melt spinning conditions can be appropriately set depending on the type of resin composition so that the resin melts and a bonded structure can be formed. For example, the cylinder temperature can be set to 150 to 190°C, and the nozzle temperature can be set to 180±15°C.

[0043] 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).

[0044] 1.3.3 Nozzle for Melt Extrusion In the spinning process according to one embodiment of the present invention, it is preferable to use the nozzle described below. The nozzle for melt extrusion of artificial hair fibers according to one embodiment of the present invention can have one or more C-shaped nozzle holes, or two or more rod-shaped nozzle holes. Figures 13A and 13D show two C-shaped nozzle holes, Figures 14A and 14B show three C-shaped nozzle holes, Figure 15 shows four C-shaped nozzle holes, Figures 16A and 16B show three rod-shaped nozzle holes, and Figure 17 shows four rod-shaped nozzle holes. When producing artificial hair fibers having a circular cross section as shown in FIG. 7, a nozzle having one C-shaped nozzle hole can be used. When producing artificial hair fibers having a cross section in the shape of two C-shaped joined shapes as shown in FIGS. 1 to 3, a nozzle having two C-shaped nozzle holes as shown in FIG. 13 can be used. When producing artificial hair fibers having a cross section in the shape of three C-shaped joined shapes as shown in FIG. 5, a nozzle having three C-shaped nozzle holes as shown in FIG. 14 can be used. When producing artificial hair fibers having a cross section in the shape of four C-shaped joined shapes as shown in FIG. 15, a nozzle having four C-shaped nozzle holes as shown in FIG. 15 can be used. When producing artificial hair fibers having a substantially triangular cross section as shown in FIG. 9, a nozzle having three rod-shaped nozzle holes as shown in FIG. 16 can be used. When producing artificial hair fibers having a substantially rectangular cross section as shown in FIG. 11, a nozzle having four rod-shaped nozzle holes as shown in FIG. 17 can be used.

[0045] The nozzle may have a separation portion, and may have a separation portion 23 on the opening surface. As described above, during melt extrusion, at least a portion of the resin composition is separated by the separation portion 23, but after being discharged from the nozzle hole, the resin composition comes into contact with each other and fuses to form a hollow portion. In one embodiment of the present invention, it is presumed that the resin composition discharged from the nozzle hole expands due to the die swell effect, making it possible to form the above-mentioned joint portion.

[0046] In the nozzle, when the minor axis length of the nozzle hole at the opening surface of the nozzle is A and the length of a line connecting points at which the distances from the nozzle hole inner surface 22 and the nozzle hole outer surface 21 at the opening surface of the nozzle are equal, B / A is preferably 3 to 20. B / A is, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, and may be within a range between any two of the numerical values ​​exemplified here.

[0047] The minor axis length A can be the shortest distance between the nozzle hole outer surface 21 and the nozzle hole inner surface 22, and can be the distance between the nozzle hole outer surface 21 and the nozzle hole inner surface 22 at a location farthest from the separation portion 23. When there is one separation portion 23, the minor axis length A can be the distance between the nozzle hole outer surface 21 and the nozzle hole inner surface 22 at a location facing the separation portion. When there are two or more separation portions, the minor axis length A can be the distance between the nozzle hole outer surface 21 and the nozzle hole inner surface 22 at a midpoint between adjacent separation portions.

[0048] B is the length of a line connecting points at the opening surface of the nozzle hole that are equidistant from the nozzle hole inner surface 22 and the nozzle hole outer surface 21, and the points constituting B are at least A / 2 away from the outer periphery of each nozzle hole. That is, B starts at a point A / 2 away from one end and ends at a point A / 2 away from the other end.

[0049] When there are multiple nozzle holes, it is preferable that B / A of each nozzle hole is within the above-mentioned numerical range. Furthermore, it is preferable that Bt / At, calculated from the sum At of A1, A2, ..., An of the multiple nozzle holes in the nozzle opening surface and the sum Bt of B1, B2, ..., Bn of the multiple nozzle holes, is within the above-mentioned numerical range. By having B / A within the above-mentioned numerical range, the wall thickness and the size of the hollow portion of the artificial hair fiber can be adjusted, and artificial hair fiber with a higher structure retention rate can be obtained while maintaining the hollow portion.

[0050] In the nozzle, when the minor axis length of the nozzle hole at the nozzle opening surface is A and the separation distance between the nozzle holes is C, it is preferable that C / A is 0.5 to 1.5. C / A is, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5, and may be within a range between any two of the values ​​exemplified here. When there are multiple nozzle holes, it is preferable that Coverage / Aaverage, calculated from the average value Coverage of the multiple separation distances C and the average value Aaverage of A of the multiple nozzle holes, falls within the above numerical range. When C / A is within the above numerical range, a joint can be more reliably formed, and an artificial hair fiber with a higher structure retention rate can be obtained while maintaining a hollow portion.

[0051] It is more preferable that the nozzle has at least one of a nozzle hole inner protrusion 26 and a nozzle hole outer protrusion 27 on the nozzle opening surface. By providing the nozzle hole inner protrusion 26 and the nozzle hole outer protrusion 27, the bonding surface of the artificial hair fiber can be further increased. Note that the nozzle hole inner protrusion 26 and the nozzle hole outer protrusion 27 are not essential for forming the protrusions on the cross section of the artificial hair fiber. As described above, in one embodiment of the present invention, the resin composition expands due to the die swell effect after being extruded from the nozzle hole, which is thought to form a bonded portion (protrusion) with an increased bonding surface area. Therefore, protrusions can be formed even if the nozzle does not have the nozzle hole inner protrusion 26 or the nozzle hole outer protrusion 27 on the nozzle opening surface.

[0052] The nozzle may have a nozzle hole inner protrusion 26 and a nozzle hole outer protrusion 27 on the nozzle opening surface ( FIG. 13D ), or may have only the nozzle hole inner protrusion 26 ( FIGS. 13C , 14B , and 16B ), or only the nozzle hole outer protrusion 27 ( FIG. 13B ). It is preferable that the nozzle has at least the nozzle hole inner protrusion 26 on the nozzle opening surface. From the viewpoint of improving the feel of the resulting artificial hair fiber, it is preferable that the nozzle has only the nozzle hole inner protrusion 26 and not the nozzle hole outer protrusion 27 on the nozzle opening surface. Note that FIG. 13 shows an embodiment in which the nozzle hole inner protrusion 26 and / or the nozzle hole outer protrusion 27 are provided on a nozzle having two C-shaped nozzle holes, but the nozzle hole inner protrusion 26 and / or the nozzle hole outer protrusion 27 can also be provided on one or more other C-shaped nozzle holes or two or more rod-shaped nozzle holes.

[0053] 1.3.4 Drawing Step and Heat Treatment Step The method for producing artificial hair fiber according to one embodiment of the present invention may also include a drawing step and a heat treatment step. In the drawing step, the undrawn artificial hair fiber obtained in the melt spinning step described above is drawn using 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 at 90 to 110°C in an air atmosphere. Furthermore, in the heat treatment step, the drawn artificial hair fiber can be heat-treated using a heat treatment machine. As an example, in the heat treatment step, the drawn artificial hair fiber is heat-treated in an air atmosphere at 90 to 110°C to 0.5 to 3.0 times its original length, and then heat-shrunk until the entire fiber length is 75% of its pre-treatment length, thereby obtaining heat-treated artificial hair fiber with a fineness of 30 to 70 denier.

[0054] 1.3.5 Gear Processing Step The method for producing artificial hair fibers according to one embodiment of the present invention can also include a gear processing step. In this gear processing step, crimping can be achieved 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 gear fractions are not particularly limited. In the gear processing step, the shape of the resulting artificial hair fibers 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 account 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 mm to 6 mm, preferably 0.5 mm to 5 mm, the gear surface temperature can be 30°C to 100°C, preferably 40°C to 80°C, and the processing speed can be 0.5 to 10 m / min, preferably 1.0 m / min to 8.0 m / min.

[0055] The total fineness of the fiber bundles used in gear processing is not particularly limited, but can be 100,000 to 2,000,000 decitex, preferably 500,000 to 1,500,000 decitex. By setting the total fineness of the fiber bundles at or above the lower limit, the productivity of gear processing can be increased and thread breakage during gear processing can be suppressed. On the other hand, by setting the total fineness of the fiber bundles at or below the lower limit, a more uniform wave shape can be obtained. In the present invention, artificial hair fibers include artificial hair fibers after spinning, and encompass artificial hair fibers before the drawing process, after the drawing process, before the heat treatment process, after the heat treatment process, before the gear processing process, and after the gear processing process.

[0056] 1.4 Hair Accessory Product A hair accessory product according to one embodiment of the present invention comprises the above-described artificial hair fiber. Also, a hair accessory product according to one embodiment of the present invention comprises the above-described artificial hair fiber bundle.

[0057] The artificial hair fiber according to the present invention can be used in hair accessory products, such as wigs, hairpieces, braids, and hair extensions. Hair accessory products obtained from the artificial hair fiber according to the present invention maintain their hollow structure with high accuracy even after undergoing processing steps after melt extrusion. This results in many advantages, such as being lightweight, allowing the desired voluminous hairstyle to be achieved with a small amount of fabric, allowing a wide range of hairstyles to be achieved, including heavy long styles, reducing damage to natural hair and the scalp, and reducing waste and environmental impact.

[0058] 2. Second Aspect 2.1 Artificial Hair Fiber 2.1.1 Shape The 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 a cross section perpendicular to the longitudinal direction of the artificial hair fiber has at least one of an inner protrusion protruding toward the hollow portion and an outer protrusion protruding toward the outside of the artificial hair fiber. The following will mainly explain the differences from the first aspect.

[0059] The artificial hair fiber according to the second aspect has a hollow portion. The shape of the hollow portion and the advantages of having a hollow portion are the same as those of the first aspect.

[0060] The cross section perpendicular to the longitudinal direction of the artificial hair fiber according to one embodiment of the present invention can be, as in the first aspect, a circular shape (Figs. 7A to 7C) or an elliptical shape, a bilobal shape with two C-shaped members joined together (Figs. 1A to 1C), a trilobal shape with three C-shaped members joined together (Figs. 5A to 5C), a quadrilobal shape with four or more C-shaped members joined together, an approximately triangular shape (Figs. 9A to 9B), an approximately quadrangular shape (Figs. 11A to 11C), or an approximately polygonal shape.

[0061] A cross section perpendicular to the longitudinal direction of the artificial hair fiber according to the second aspect has at least one of inner protrusions 16 protruding toward the hollow portion and outer protrusions 17 protruding toward the outside of the artificial hair fiber. The artificial hair fiber may have inner protrusions 16 and outer protrusions 17 as shown in Figures 2 and 7, or may have either inner protrusions 16 or outer protrusions 17, preferably having at least inner protrusions 16, or may have only inner protrusions 16 as shown in Figures 1, 5, 9, and 11. From the viewpoint of improving the feel of the artificial hair fiber, it is preferable that the outer protrusions are small in size and frequency, and it is preferable that the outer protrusions 17 are smaller or less frequent than the inner protrusions 16, and it is more preferable that the artificial hair fiber have only inner protrusions 16.

[0062] The protrusions have been described in the first aspect, but will now be described based on a representative embodiment. Figures 7A to 7C show cross sections of an artificial hair fiber having inner protrusions 16 and outer protrusions 17 in a circular cross section perpendicular to the longitudinal direction, while Figure 8 shows a cross section of a comparative example having no protrusions. In this embodiment, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​exemplified here. Here, the protrusion height Z can be defined as the distance from a tangent to the apex of the protrusion at the intersection of a virtual inner surface (outer surface) (dashed line in Figure 7C) extending from the inner surface 12 (or outer surface 11) other than the protrusions assuming that the protrusions do not exist, and a straight line extending in the direction of the protrusions through the center of the protrusions.

[0063] When a cross section perpendicular to the longitudinal direction of an artificial hair fiber has a multi-lobed shape formed by bonding multiple C-shaped members, cross sections having inner protrusions 16 and outer protrusions 17 are shown in Figures 2A to 2C, cross sections having only inner protrusions 16 are shown in Figures 1A to 1C and 5A to 5C, cross sections having only outer protrusions 17 are shown in Figures 3A to 3C, and a cross section equivalent to a comparative example having no protrusions is shown in Figure 4. In these embodiments, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​exemplified here. Here, Z can be the distance from a tangent line passing through two points on the inner (or outer) surfaces of two adjacent C-shaped members via a protrusion to the apex of the protrusion (Figures 1C, 2C, 3C, and 5C). Figures 1, 2, 3, and 5 show cases where the cross section perpendicular to the longitudinal direction of the artificial hair fiber is a bilobal cross section formed by joining two or three C-shaped pieces, but the protrusions and their heights can also be specified in the same way when the cross section is a quadrilobular cross section or more.

[0064] 9A-9B and 11A-11B show cross sections of artificial hair fibers having only inner protrusions 16 when the cross section perpendicular to the longitudinal direction is a polygonal shape such as a substantially triangular or substantially rectangular shape, while FIGS. 10 and 12 show cross sections of comparative examples having no protrusions. In these embodiments, "having protrusions" refers to a protrusion height Z of 1 μm or more. The protrusion height Z may be, for example, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, or 50 μm, or may be within a range between any two of the values ​​shown here. Here, Z is the distance from a line including a vertex perpendicular to the bisector of the angle of a polygon on the imaginary inner surface (outer surface) (dashed lines in FIGS. 9B and 11B) obtained by extending the inner surface 12 (or outer surface 11) other than the protrusions assuming that the protrusions are absent, to the vertex of the protrusion. Figures 9 and 11 show cases where the cross section perpendicular to the longitudinal direction of the artificial hair fiber is approximately triangular or approximately rectangular, but the protrusions and protrusion heights can be similarly specified even in cases where the cross section is pentagonal or larger.

[0065] The protrusions may include a joining surface and a joining portion where the resin compositions come into contact and fuse together. In a second aspect, the cross section of the fiber for artificial hair may include a protrusion that does not include a joining surface or a joining portion. The fiber for artificial hair according to one embodiment of the present invention has a structure having a hollow portion and protrusions, which significantly improves the structural retention rate of the fiber for artificial hair and enables the hollow structure of the fiber for artificial hair to be stably maintained with high accuracy.

[0066] In the second aspect, the maximum value of the thickness X of the inner protrusion 16 and the outer protrusion 17 at the center in a cross section perpendicular to the longitudinal direction of the artificial hair fiber is X ＭＡＸ , when the thickness of the thinnest portion other than the inner protrusion and the outer protrusion is Y, X ＭＡＸ / Y can be 0.90 to 2.50, preferably 1.00 to 2.50, and more preferably 1.05 to 2.50. ＭＡＸ / Y may be, for example, 0.90, 0.95, 1.00, 1.05, 1.10, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 2.10, 2.20, 2.30, 2.40, or 2.50, or may be within a range between any two of the values ​​exemplified here.

[0067] The thickness X of the center of the inner protrusion 16 and the outer protrusion 17 can be the thickness when crossing the center of the protrusion in the direction of the protrusion. When the cross section perpendicular to the longitudinal direction of the artificial hair fiber has multiple protrusions, X ＭＡＸ can be the maximum value of multiple X's. A thicker thickness at the center means that the area of ​​the joint surface 14 is wider. The thickness Y of the thinnest part other than the inner protrusion 16 and the outer protrusion 17 can be the shortest distance between the outer surface 11 and the inner surface 12 at the part other than the inner protrusion 16 and the outer protrusion 17. The thickness Y of the thinnest part can be the thickness at the part farthest from any joint. When there is one joint 13, the thickness Y of the thinnest part can be the thickness at the part facing the joint. When there are two or more joints 13, the thickness Y of the thinnest part can be the thickness at the midpoint between adjacent joints. X ＭＡＸBy setting / Y to the above lower limit or more, sufficient strength can be imparted to the joint 13. In one embodiment of the present invention, when the artificial hair fiber has multiple protrusions in one cross section, it is more preferable that X / Y, calculated from the thickness X of the center of each protrusion, is within the above numerical range.

[0068] X can be 5 to 70 μm. X can be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 μm, and may be within a range between any two of the values ​​exemplified here. Y can be 5 to 40 μm. Y can be, for example, 5, 10, 15, 20, 25, 30, 35, or 40 μm, and may be within a range between any two of the values ​​exemplified here. Furthermore, the artificial hair fiber according to one embodiment of the present invention can have a thickness of 5 μm or more at its thinnest point. The thickness of the thinnest point can be, for example, 5, 10, 15, 20, 25, 30, 35, or 40 μm, and may be within a range between any two of the values ​​exemplified here. In conventional artificial hair fibers, separation and crushing of the structure may occur starting from thin portions of the fiber. However, in the artificial hair fiber according to one embodiment of the present invention, the thicknesses X and Y are within the above-mentioned numerical ranges, and / or the thickness of the thinnest portion is equal to or greater than the above-mentioned lower limit, thereby making it possible to further suppress separation and crushing of the structure.

[0069] The cross-sectional shape of the artificial hair fiber can be controlled by the composition of the resin composition for artificial hair fiber that constitutes the artificial hair fiber, the melt extrusion conditions, and the shape of the nozzle used for melt extrusion.

[0070] 2.1.2 Composition The composition of the artificial hair fiber according to the second aspect can be the same as that of the first aspect.

[0071] 2.2 Artificial Hair Fiber Bundle The composition of the artificial hair fiber bundle according to the second aspect can be the same as that of the first aspect.

[0072] 2.3 Manufacturing method of artificial hair fiber The manufacturing method of the artificial hair fiber according to the second aspect is not particularly limited, and any manufacturing method can be used as long as it can obtain an artificial hair fiber having a hollow portion and a structure in which the cross section perpendicular to the longitudinal direction of the artificial hair fiber has at least one of an inner protrusion and an outer protrusion. As an example, the artificial hair fiber according to the second aspect can be obtained by the same method as in the first aspect, and the same nozzle as the nozzle described in the first aspect can be used as the nozzle for melt extrusion.

[0073] 2.4 Hair Accessory Product The hair accessory product according to the second aspect may be similar to that according to the first aspect.

[0074] 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.

[0075] Example 1 <Preparation of Resin Composition for Artificial Hair Fibers> 70 parts by mass of polyvinyl chloride resin (manufactured by Taiyo Vinyl Corporation, product name: TH1000), 30 parts by mass of a vinyl copolymer resin (manufactured by the company, GR-AT-6S) containing 68% by mass of styrene monomer units and 32% by mass of acrylonitrile monomer units, a total of 5 parts by mass of additives such as plasticizers, stabilizers, and lubricants (specifically, 3 parts by mass of a stabilizer composition, 1 part by mass of epoxidized soybean oil, 0.4 parts by mass of a phosphorus-based chelating agent, and 0.6 parts by mass of polyethylene wax), and 0.5 parts by mass of carbon black were mixed in a blender. The blended materials were kneaded using a φ40 mm single-screw extruder to obtain Resin Composition 1 for Artificial Hair Fibers in the form of pellets for spinning. The stabilizer composition used to obtain the resin composition had the following components and composition: Hydrotalcite compound (Mg ４ Al ２ (OH)CO ３ ・3H ２O) 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 (product name: TH1000 manufactured by Taiyo PVC Co., Ltd.) 8.9 parts by mass 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-based chelating agent: "ADEKA STAB (registered trademark) 1030" manufactured by ADEKA Corporation Polyethylene wax: manufactured by Mitsui Chemicals, Inc.

[0076] <Spinning Process> The obtained pellet-shaped resin composition for artificial hair fibers was spun using nozzle 1 in a φ40 mm single-shaft melt spinning machine. Note that nozzle 1 was a nozzle with two identical C-shaped nozzle holes with inward protrusions, as shown in the schematic diagram of FIG. 13C . For each nozzle hole of nozzle 1, the minor axis length of the nozzle hole at the nozzle opening surface was defined as A, and the length of the line connecting the points at equal distances from the inner and outer surfaces at the nozzle opening surface was defined as B. In addition, the minor axis length of each nozzle hole at the nozzle opening surface was defined as A, and the separation distance between the two nozzle holes was defined as C, and the C / A was 1.0. The molten resin discharged from the nozzle was used to produce undrawn yarn by adjusting the discharge rate and take-up speed. Note that the cylinder temperature and nozzle temperature of the spinning machine were set to 140 to 180°C.

[0077] <Drawing step and heat treatment step> The obtained undrawn yarn was drawn at 100°C and then annealed at 100 to 200°C to obtain artificial hair fiber 1. The draw ratio was 3 times, and the relaxation rate during annealing was 0.5 to 3%. The relaxation rate during annealing is a value calculated by (rotational speed of the take-up roller during annealing) / (rotational speed of the delivery roller during annealing).

[0078] Examples 2 to 11, Comparative Examples 1 and 2 Artificial hair fibers 2 to 13 were obtained in the same manner as in Example 1, except that nozzles 2 to 13 were used as the nozzles in the spinning process. Nozzles 2, 3, and 6 to 11 each had two identical C-shaped nozzle holes with inward protrusions, as shown in the schematic diagram of FIG. 13C, with B / A and C / A as shown in Table 1. Nozzle 4 had three identical rod-shaped nozzle holes with inward protrusions, as shown in the schematic diagram of FIG. 16B, with B / A and C / A as shown in Table 1. Nozzle 5 had three identical C-shaped nozzle holes with inward protrusions, as shown in the schematic diagram of FIG. 14A, with B / A and C / A as shown in Table 1. As shown in FIG. 13B , the nozzle 12 has two identical C-shaped nozzle holes with outward protrusions, and B / A and C / A are as shown in Table 1. As shown in the schematic diagram of FIG. 14A , the nozzle 12 has three identical C-shaped nozzle holes, and B / A and C / A are as shown in Table 1. As shown in the schematic diagram of FIG. 15 , the nozzle 13 has four identical C-shaped nozzle holes, and B / A and C / A are as shown in Table 1.

[0079]

[0080] (Method for evaluating artificial hair fibers) The obtained artificial hair fibers were evaluated by the following method. For cross-sectional observation, the artificial hair fibers were cut to an appropriate length, the resulting bundle was wrapped in vinyl tape, and the bundle was cut perpendicular to the longitudinal direction with a cutter knife to prepare a cross section.

[0081] <Cross-section observation> A cross-section photograph of the fiber was taken at a magnification of 400 times using a laser microscope to confirm the presence or absence of protrusions. In addition, the thickness X of the thick part at the center of the inner protrusion and the outer protrusion, and the thickness Y of the thinnest part other than the inner protrusion and the outer protrusion were measured. ＭＡＸ / Y was calculated.

[0082] <Area ratio of hollow portions> A cross-section of the fiber was photographed at a magnification of 400 times using a laser microscope, and the area ratio of hollow portions in the cross section was calculated with an N number of 30. Area ratio of hollow portions in the cross section = Area surrounded by inner surface / Area surrounded by outer surface

[0083] <Structure Retention Rate> Using a laser microscope, the cross section of the fiber was photographed at a magnification of 400 times. Then, with an N number of 300, the structure retention rate was calculated based on the following formula. The structure retention rate was calculated as follows: Structure retention rate = (300 - i - j) / 300, where i is the number of fibers having one or more separated junctions, and j is the number of fibers whose hollow portions were crushed and whose inner surfaces came into contact with each other.

[0084] <Volume> A 120 g fiber bundle was prepared using artificial hair fibers cut to a length of 120 cm, and the fibers were folded back to a length of 60 cm and placed in a partition with a width of 39.5 mm. The height of the sample was then measured, and the specific volume was calculated based on the following formula: Partition width × sample length × sample height ÷ fiber mass = specific volume (cc / g).

[0085] <Touch> The artificial hair fibers of the Examples and Comparative Examples were bundled to a length of 250 mm and a mass of 20 g, and the touch was judged by 10 artificial hair fiber processing technicians (with 5 years or more of work experience) according to the following evaluation criteria: 4: 9 or more technicians evaluated the touch as good 3: 6 to 8 technicians evaluated the touch as good 2: 3 to 5 technicians evaluated the touch as good 1: 2 or less technicians evaluated the touch as good

[0086] A laser microscope photograph of the cross section of the artificial hair fiber according to Example 2 is shown in Figure 18, a laser microscope photograph of the cross section of the artificial hair fiber according to Example 5 is shown in Figure 19, a laser microscope photograph of the cross section of the artificial hair fiber according to Comparative Example 1 is shown in Figure 21A, and a laser microscope photograph of the cross section of the artificial hair fiber according to Comparative Example 2 is shown in Figure 21B. From the observation results, it was confirmed that the cross sections of the artificial hair fibers according to the Examples had a strength-enhancing structure (protrusions) at the joints to improve the bonding strength, and that the protrusion height Z was 1 µm or more. Furthermore, in the cross section of the artificial hair fiber according to the Comparative Example, the thickness of the joints was thinner than the thickness of areas other than the joints, and no protrusions were observed.

[0087] 100: Cross section of artificial hair fiber, 11: Outer surface, 12: Inner surface, 13: Joint portion, 14: Joint surface, 15: Hollow portion, 16: Inner protrusion, 17: Outer protrusion, 18: Major diameter, 19: Joint strength enhancing structure, X: Thickness at the center of the thickest protrusion, Y: Thickness of the thinnest portion, Z: Protrusion height, 200: Nozzle hole, 21: Outer surface of nozzle hole, 22: Inner surface of nozzle hole, 23: Separation portion, 24: Inner protrusion of nozzle hole, 25: Outer protrusion of nozzle hole, A: Minor axis length, B: Length of line connecting points at equal distances from the inner and outer surfaces, C: Separation distance

Claims

1. An artificial hair fiber, comprising: a hollow portion extending in the longitudinal direction of the artificial hair fiber; a cross section perpendicular to the longitudinal direction of the artificial hair fiber comprises at least one joint portion, the joint portion comprising a strength enhancing structure for improving the bonding strength.

2. The artificial hair fiber according to claim 1, wherein the strength-enhancing structure is thicker than other portions to improve bonding strength.

3. The artificial hair fiber according to claim 1, wherein the strength enhancing structure comprises at least one of an inner protrusion protruding toward the hollow portion and an outer protrusion protruding toward the outside of the artificial hair fiber.

4. A fiber for artificial hair, comprising a hollow portion extending in the longitudinal direction of the fiber for artificial hair, and a cross section perpendicular to the longitudinal direction of the fiber for artificial hair comprises at least one of an inner protrusion protruding toward the hollow portion and an outer protrusion protruding toward the outside of the fiber for artificial hair.

5. The artificial hair fiber according to claim 1 or 4, wherein the hollow portion occupies 5 to 50% of the area of ​​the cross section perpendicular to the longitudinal direction of the artificial hair fiber.

6. The maximum thickness X of the inner protrusion and the outer protrusion at the center is X ＭＡＸ , where Y is the thickness of the thinnest portion other than the inner protrusion and the outer protrusion, X ＭＡＸ 5. The fiber for artificial hair according to claim 3, wherein / Y is 0.90 to 2.

50.

7. The fiber for artificial hair according to claim 1 or 4, which contains a vinyl chloride resin.

8. A hair accessory product comprising the artificial hair fiber according to claim 1 or 4.

9. A nozzle for melt extrusion of the artificial hair fiber according to claim 1 or 4, comprising one or more C-shaped nozzle holes or two or more rod-shaped nozzle holes.

10. The nozzle according to claim 9, wherein, in the opening plane of the nozzle, the minor axis length of the nozzle hole is A and the length of a line connecting points at which the inner surface of the nozzle hole and the outer surface of the nozzle hole are equidistant is B, where B / A is 3 to 20.

11. The nozzle according to claim 9, wherein, in an opening surface of the nozzle, when the minor axis length of the nozzle hole is A and the distance between the nozzle holes is C, C / A is 0.5 to 1.5.

Images