Fiber for artificial hair and hair ornament product

Abstract

The present invention addresses the problem of providing: a fiber for artificial hair having excellent ease-of-combing; and a hair ornament product comprising the fiber for artificial hair.　One embodiment of the present invention is a fiber for artificial hair comprising a hollow section that extends in the length direction of the fiber for artificial hair. When a stress of 150 N / cm2 is applied, in the width direction, to a fiber-for-artificial-hair bundle composed of a plurality of the fibers for artificial hair, a hollowness-maintaining rate based on before the stress was applied is 90% or more.

Description

Artificial hair fibers and hair accessories

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

[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 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 having hollow portions with a hollow ratio of 10 to 50%. Patent Document 2 discloses fibers for artificial hair 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 with respect to the major axis of the fiber cross section.

[0004] JP 2008-285772 A

[0005] From the viewpoint of preventing discomfort to the user, it is preferable that artificial hair fibers have an excellent feel when used. In particular, conventional artificial hair fibers have sometimes had poor combability when used. Here, the combability of a fiber bundle refers to the degree of ease with which fingers can be combed through the fiber bundle when combing it with a hand.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a fiber for artificial hair that is easy to comb.

[0007] As a result of extensive research, the present inventors have found that the above problems can be solved by providing artificial hair fibers with a specific hollow retention rate against stress, and have thus completed the present invention.

[0008] According to the present invention, the following is provided: [1] An artificial hair fiber, the artificial hair fiber having a hollow portion extending in the longitudinal direction of the artificial hair fiber, and a fiber bundle for artificial hair consisting of a plurality of the artificial hair fibers, having a strength of 150 N / cm in the transverse direction. ２ [2] When a stress of 200 N / cm is applied to the fiber bundle for artificial hair in the transverse direction, the hollow retention rate is 90% or more, based on the state before the stress is applied. ２ [1] The artificial hair fiber according to [1], wherein when a stress of 100 kJ / cm is applied, the hollow retention rate is 80% or more based on the state before the stress is applied. [3] The artificial hair fiber according to [1] or [2], wherein the hollow rate in the fiber cross section perpendicular to the longitudinal direction of the artificial hair fiber is 5 to 50%. [4] The artificial hair fiber according to any of [1] to [3], wherein the artificial hair fiber contains a vinyl chloride resin. [5] A hair accessory product comprising the artificial hair fiber according to any of [1] to [4]. [6] The hair accessory product according to [5], wherein the hair accessory product contains a braid.

[0009] According to the present invention, it is possible to provide an artificial hair fiber that is excellent in combability, and a hair accessory product including the artificial hair fiber.

[0010] Figure 1 shows schematic cross-sectional views of an artificial hair fiber according to one embodiment of the present invention: Figure 1A shows a circular cross-section, Figure 1B shows a circular cross-section with inner and outer protrusions, Figure 1C shows a bilobal cross-section formed by joining two C-shaped portions, Figure 1D shows a trilobal cross-section formed by joining three C-shaped portions, Figure 1E shows a substantially triangular cross-section, and Figure 1F shows a substantially rectangular cross-section.

[0011] The present invention will be described in detail below. However, the present invention is not limited to these descriptions. The features of the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0012] <Explanation of Terms> In this specification, for example, the expression "X to Y" means that X or more and Y or less.

[0013] 1. Artificial Hair Fiber 1.1 Shape of Artificial Hair Fiber The artificial hair fiber according to this embodiment has a hollow portion extending in the longitudinal direction of the artificial hair fiber. In this specification, a "hollow portion" refers to a portion that is continuously present for 3 cm or more in the longitudinal direction of the artificial hair fiber and has a major diameter of 1 μm or more in the cross section of the fiber. The artificial hair fiber may have hollow portions of 3 cm or more (preferably 4 cm, 5 cm, or 10 cm) or more in the longitudinal direction, interspersed with non-hollow portions of 1 cm or less (preferably 0.5 cm). In this case, it is preferable that 80% (preferably 90%) or more of the total length of the artificial hair fiber in the longitudinal direction be hollow. Furthermore, there may be multiple hollow portions in the cross section perpendicular to the longitudinal direction of the artificial hair fiber. The artificial hair fiber according to the embodiment is lightweight because it has a hollow portion, and offers many advantages, such as being able to create the desired voluminous hairstyle with a small amount of wear, being able to achieve a wide range of hairstyles including heavy long styles, being able to reduce damage to one's own hair and scalp, and being able to reduce waste and environmental impact.

[0014] An example of a cross section perpendicular to the longitudinal direction of the artificial hair fiber according to this embodiment is shown in Figure 1. The cross section perpendicular to the longitudinal direction of the artificial hair fiber according to this embodiment can have any one shape selected from a circular shape (Figures 1A and 1B), an elliptical shape, a bilobal shape with two joined C-shaped portions (Figure 1C), a trilobal shape with three joined C-shaped portions (Figure 1D), a quadrilobal shape with four or more joined C-shaped portions, etc., as well as a substantially triangular shape (Figure 1E), a substantially square shape (Figure 1F), and a substantially polygonal shape.

[0015] While the method for producing the artificial hair fiber according to this embodiment is not particularly limited, the artificial hair fiber is generally obtained by melt-spinning a resin composition. 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. The artificial hair fiber according to this embodiment can have a bonding surface 14 (shown by a dashed line in FIG. 1) where the resin composition fuses with each other during the melt-extrusion process. Furthermore, the bonding surface 13, which is the region including the bonding surface 14, may have at least one of an inner protrusion 16 protruding toward the hollow portion and an outer protrusion 17 protruding toward the outside of the artificial hair fiber (FIG. 1B). 1B shows a case where the fiber cross section is circular, but even when the hollow portion has another shape, the joint can be provided with 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. In this way, by providing a protrusion to thicken the joint 13 and increasing the area of ​​the joint surface 14 where the resin compositions are fused together, the joint strength can be improved. The manufacturing method will be described later.

[0016] In the artificial hair fiber according to this embodiment, the major axis (fineness) in a cross section perpendicular to the longitudinal direction of the artificial hair fiber is preferably 10 to 100 μm, more preferably 20 to 80 μm, and even more preferably 30 to 60 μm. The major axis is, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 μm, and may be within a range between any two of the values ​​exemplified here. When the major axis of the artificial hair fiber according to this embodiment is within this range, the hollow retention rate is improved, and thus the artificial hair fiber bundle has better combability.

[0017] The artificial hair fiber according to this embodiment preferably has a hollow ratio of 5 to 50%, more preferably 10 to 45%, and even more preferably 20 to 40%, where the hollow ratio is the area ratio occupied by hollow portions in a cross section perpendicular to the longitudinal direction of the artificial hair fiber. The hollow ratio may be, 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 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 refers to the cross-sectional area assuming that the artificial hair fiber has no hollow portions. Furthermore, if there are multiple hollow portions in a cross section perpendicular to the longitudinal direction of the artificial hair fiber, the area enclosed by the inner surface 12 can be calculated as the sum of the areas enclosed by the inner surfaces of each 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. When the hollowness according to this embodiment is within this range, the advantages of having hollow portions can be more reliably obtained. Specifically, when the hollowness is within this range, structural defects (such as when joints separate or hollow portions are crushed) are suppressed, and an increase in rigidity due to an increase in fineness can be prevented, improving the feel. Furthermore, when the upper limit of the hollowness is within this range, the artificial hair fiber bundle has better combability.

[0018] 1.2 Composition of Artificial Hair Fiber 1.2.1 Resin The resin composition constituting the artificial hair fiber according to this embodiment is not particularly limited and may contain at least one resin selected from the group consisting of vinyl chloride resin, AS resin (acrylonitrile-styrene resin), polyester resin, polyamide resin, and polyolefin resin. From the viewpoint of easily achieving the die swelling effect described below, the artificial hair fiber according to this embodiment preferably contains a vinyl chloride resin. Furthermore, the artificial hair fiber according to this embodiment preferably contains a vinyl chloride resin and an AS resin. The resin composition constituting the artificial hair fiber according to this embodiment preferably contains 70% by mass or more of resin, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the resin composition. Specifically, the resin content may be, for example, 70, 75, 80, 85, 90, 94, 95, 96, 97, 98, 99, or 100% by mass, and may be within a range between any two of the values ​​exemplified here.

[0019] 1.2.1.1 Vinyl Chloride Resin The vinyl chloride resin according to this embodiment may include a vinyl chloride polymer containing monomer units (vinyl chloride monomer units) derived from vinyl chloride monomer. The vinyl chloride resin according to this embodiment may include 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 this embodiment may consist of one type of vinyl chloride polymer, or may contain two or more types of vinyl chloride polymers.

[0020] The resin composition constituting the artificial hair fiber according to this embodiment preferably contains 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more of vinyl chloride resin per 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 100% by mass, and may be within a range between any two of the values ​​exemplified here.

[0021] 1.2.1.2 AS-Based Resin AS-based resin (acrylonitrile-styrene-based resin) is a copolymer containing styrene-based monomer units and acrylonitrile-based monomer units, and may contain other monomer units copolymerizable with these as necessary. The resin composition constituting the artificial hair fiber according to this embodiment preferably contains 5 to 50% by mass of AS-based resin, more preferably 10 to 40% by mass, and even more preferably 20 to 30% by mass, based on 100% by mass of the resin composition. The AS-based resin 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-based resin, and may be within a range between any two of the values ​​exemplified here. The AS resin may contain, for example, 10, 15, 20, 25, 30, 35, or 40% by mass of acrylonitrile monomer units relative to 100% by mass of the AS resin, and may be within a range between any two of the numerical values ​​exemplified here.

[0022] 1.2.1.3 Polyester-Based Resin Examples of polyester-based resins according to this embodiment include aromatic polyester-based resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and aliphatic polyester-based resins such as polylactic acid, polyhydroxybutyric acid, polycaprolactone, polybutylene succinate, polybutylene adipate, polyethylene succinate, polyglycolic acid, poly-3-hydroxypropionate, and poly-3-hydroxybutyrate. These polyester-based resins may be used alone or in combination of two or more.

[0023] 1.2.1.4 Polyamide-Based Resin Examples of polyamide-based resins according to this embodiment include nylon 6, nylon 66, nylon 11, nylon 12, nylon 6.10, nylon 6.12, and copolymers thereof. These polyamide-based resins may be used alone or in combination of two or more.

[0024] 1.2.1.5 Polyolefin Resin Examples of the polyolefin resin according to this embodiment include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-propylene copolymer. These polyolefin resins may be used alone or in combination of two or more.

[0025] 1.2.2 Other Components The artificial hair fiber according to this embodiment may contain other components as needed. These other components include stabilizers, antistatic agents, heat stabilizers, lubricants, colorants, processing aids, plasticizers, reinforcing agents, UV absorbers, antioxidants, fillers, flame retardants, pigments, initial coloring improvers, conductivity imparting agents, and fragrances. Examples of other components according to this embodiment include hydrotalcite compounds, organic acid zinc salts (e.g., zinc stearate), silica, β-diketone compounds (e.g., dibenzoylmethane), polyols (e.g., dipentaerythritol), epoxy compounds (e.g., epoxidized soybean oil), organic phosphite compounds (e.g., phosphorus-based chelating agents), and polyethylene wax. The resin composition according to this embodiment may contain, for example, preferably 10 parts by mass or less, and more preferably 5.5 parts by mass or less, of other components per 100 parts by mass of resin.

[0026] 1.3 Manufacturing Method of Artificial Hair Fiber The manufacturing method of artificial hair fiber 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.

[0027] 1.3.1 Resin composition preparation step In the resin composition preparation step, raw materials including a resin are mixed to obtain a resin composition. Here, the raw materials include a base resin and may include other components as necessary.

[0028] 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 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.

[0029] 1.3.2 Spinning Process In the spinning process, 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 be melt-spun. As the extruder, a conventionally known extruder can be used, such as a single-screw extruder, a counter-rotating twin-screw extruder, or a conical twin-screw extruder.

[0030] The melt spinning conditions can be set appropriately depending on the type of resin composition so that the resin melts and a hollow portion is formed. The cylinder temperature can be set to 150 to 300°C. The cylinder temperature can be set depending on the type of resin. When the resin is a vinyl chloride resin or an AS resin, the cylinder temperature is preferably 160 to 180°C. When the resin is a polyester resin or a polyamide resin, the cylinder temperature is preferably 250 to 290°C. When the resin is a polyolefin resin, the cylinder temperature is preferably 180 to 220°C.

[0031] The nozzle temperature can be set depending on the type of resin. When the resin is a vinyl chloride resin or an AS resin, the nozzle temperature is preferably 160 to 200°C, more preferably 170 to 200°C, even more preferably 175 to 195°C, and particularly preferably 175 to 185°C. When the resin is a polyester resin or a polyamide resin, the nozzle temperature is preferably 270 to 310°C, even more preferably 280 to 300°C. When the resin is a polyolefin resin, the nozzle temperature is preferably 200 to 240°C, even more preferably 210 to 230°C. At such a nozzle temperature, the resin compositions ejected from the nozzle holes are sufficiently bonded at the joints, improving the hollow retention rate of the artificial hair fiber bundle.

[0032] 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).

[0033] The shape of the nozzle used for melt extrusion of the artificial hair fiber according to this embodiment can be appropriately selected depending on the shape and hollowness of the artificial hair fiber to be obtained. For example, when producing an artificial hair fiber having a circular cross section as shown in Fig. 1A, a nozzle with a C-shaped nozzle hole can be used. When producing an artificial hair fiber having a bilobal cross section with two C-shaped holes joined together as shown in Fig. 1C, a nozzle with two C-shaped nozzle holes can be used. When producing an artificial hair fiber having a trilobal cross section with three C-shaped holes joined together as shown in Fig. 1D, a nozzle with three C-shaped nozzle holes can be used. Furthermore, when producing an artificial hair fiber having a substantially triangular cross section as shown in Fig. 1E, a nozzle with three rod-shaped nozzle holes can be used. When producing an artificial hair fiber having a substantially rectangular cross section as shown in Fig. 1F, a nozzle with four rod-shaped nozzle holes can be used. Due to the presence of the separation between the nozzle holes, at least a part 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 to form a hollow part. In addition, in this embodiment, the resin composition discharged from the nozzle holes swells due to the die swell effect, and it is possible to form an inner protrusion and / or an outer protrusion.

[0034] Furthermore, the nozzle land length is preferably 0.2 to 3.5 mm, and more preferably 0.3 to 3.0 mm. When the lower limit of the nozzle land length is within this range, the die swell effect is more easily achieved, and the bonding surface area at the bonding portion is increased, thereby improving the hollow retention rate of the artificial hair fiber bundle. When the upper limit of the nozzle land length is within this range, a sufficient bonding surface area can be obtained even when the hollow rate is high, and further, pressure loss can be minimized to improve productivity.

[0035] 1.3.3 Drawing Step The method for producing artificial hair fibers according to this embodiment can also include a drawing step. In the drawing step according to this embodiment, the undrawn artificial hair fibers obtained in the melt spinning step described above are drawn in a drawing machine to obtain the drawn artificial hair fibers. As an example, in the drawing step, the undrawn artificial hair fibers can be drawn 2 to 5 times in an air atmosphere at 90 to 110°C.

[0036] 1.3.4 Heat Treatment Step The method for producing artificial hair fibers according to this embodiment can also include a heat treatment step. In the heat treatment step according to this embodiment, the artificial hair fibers after the drawing step can be heat-treated using a heat treatment machine. As an example, in the heat treatment step, the artificial hair fibers after the drawing step are heat-treated in an air atmosphere at 90 to 120°C so that the fibers shrink to 0.5 to 0.99 times their original size, causing the entire length of the fibers to thermally shrink, thereby obtaining artificial hair fibers with the desired fineness after the heat treatment step. The "relaxation rate during heat treatment" is a value calculated by dividing the rotational speed of the take-up roller during annealing by the rotational speed of the delivery roller during annealing.

[0037] 1.3.5 Gear Processing Step The method for producing artificial hair fibers according to this embodiment 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, the number of gear teeth, and the like 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, the pressure conditions between the gears, and the like, 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.

[0038] The method for producing artificial hair fibers according to this embodiment may include other steps, for example, a surface treatment agent application step.

[0039] In the present invention, artificial hair fibers include artificial hair fibers after spinning, and also 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.

[0040] 2. Artificial Hair Fiber Bundle The artificial hair fiber bundle according to this embodiment includes the above-mentioned artificial hair fiber. The artificial hair fiber bundle according to this embodiment is preferably made of the above-mentioned artificial hair fiber.

[0041] 2.1 Characteristics of Artificial Hair Fiber Bundle 2.1.1 Hollow Retention Rate In this embodiment, the artificial hair fiber bundle made of a plurality of the above-mentioned artificial hair fibers is subjected to a lateral force of 150 N / cm ２ When a stress of 150 N / cm is applied in the transverse direction, the hollow retention rate based on the state before the stress is applied is preferably 90% or more, more preferably 95% or more, and particularly preferably 100%. ２ When a stress of 150 N / cm is applied, the hollow retention rate based on the value before the stress is applied 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. In this specification, the "hollow retention rate" can be the hollow retention rate before and after the stress is applied to the artificial hair fiber bundle. Whether hollows are retained or not can be determined by applying a stress of 150 N / cm per unit area to a plurality of artificial hair fibers (for example, 20 to 30 fibers) laid out. ２After placing a weight, it can be determined whether the hollowness is maintained in the fiber cross section perpendicular to the longitudinal direction of the artificial hair fiber, or whether the hollowness is not maintained due to cracking of the joints, etc. Note that if there are multiple hollow portions in the cross section perpendicular to the longitudinal direction of the artificial hair fiber, and the hollow portions are connected to each other, it can be determined that the hollowness is not maintained. The hollowness retention rate can be calculated using the following formula: (Hollowness retention rate) = {(Number of fibers that maintain a hollowness after application of stress) / (Number of fibers that maintain a hollowness before application of stress)} x 100 When the hollowness retention rate is such a value, the artificial hair fiber bundle has excellent combability. Note that the artificial hair fiber used to measure the hollowness retention rate may be either artificial hair fiber after the heat treatment step, before the gear processing step, or after the gear processing step.

[0042] In this embodiment, a fiber bundle for artificial hair made of a plurality of the above-mentioned fibers for artificial hair is subjected to a short-side stress of 200 N / cm ２ When a stress of 200 N / cm is applied in the transverse direction, the hollow retention rate based on the value before the stress is applied is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. ２ When a stress of 200 N / cm is applied, the hollow retention rate based on the value before the stress is applied is, for example, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 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. Whether hollows are retained or not can be determined by applying a weight of 200 N / cm per unit area in the above-mentioned measurement method. ２ When the hollowness retention rate is within this range, the artificial hair fiber bundle has better combability.

[0043] The hollow retention rate can be improved by ensuring sufficient adhesion at the joints. Therefore, it can be improved by adjusting the melt spinning conditions in the spinning process, particularly the nozzle temperature and nozzle land length, to appropriate values. Furthermore, the hollow retention rate can also be adjusted by the major diameter and hollow rate of the artificial hair fiber.

[0044] 2.1.2 Combability The artificial hair fiber bundle according to this embodiment preferably has excellent combability. The combability of the artificial hair fiber bundle can be evaluated, for example, by the degree of ease with which a hair fiber processing technician (with at least 5 years of work experience) feels when combing a 600 mm long, 120 g mass artificial hair fiber bundle with their fingers.

[0045] 3. Hair Accessory Product The hair accessory product according to this embodiment contains the above-described artificial hair fiber.

[0046] The artificial hair fiber bundle according to this embodiment can be used for hair accessory products, such as wigs, hair pieces, braids, hair extensions, doll hair, hair wigs, false hair, and hair bands. Hair accessory products obtained from the artificial hair fiber bundle according to this embodiment have excellent combability.

[0047] Furthermore, the hair accessory product obtained from the artificial hair fiber bundle according to this embodiment maintains the hollow structure of each fiber with high accuracy, and therefore is lightweight, allowing the desired voluminous hairstyle to be achieved with a small amount of attachment, enabling a wide range of hairstyles including heavy long styles to be realized, reducing damage to one's own hair and scalp, and reducing waste and environmental impact, etc. The hair accessory product according to this embodiment can be applied to a variety of styles, but is particularly suitable for braids, including braids and twists.

[0048] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention and should not be construed as narrowing the scope of the present invention.

[0049] (Example 1) <Resin composition preparation process> 100 parts by mass of vinyl chloride resin (manufactured by Taiyo PVC Co., Ltd., product name: TH1000), 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 a resin composition in the form of pellets for spinning.

[0050] The stabilizer composition used to obtain the resin composition has the following components and composition: Hydrotalcite compound (Mg ４ Al ２ (OH) １２ CO ３ ・3H ２ O) 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

[0051] 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.

[0052] <Spinning step> The obtained pellet-shaped resin composition was spun using a φ40 mm single-screw melt spinning machine. The discharge rate and winding speed were adjusted to produce undrawn yarn from the molten resin discharged from the nozzle. The nozzle used had three shallow C-shaped nozzle holes with a cross-sectional shape. The land length, nozzle temperature, and cylinder temperature of the spinning machine nozzle are shown in Tables 1 and 2.

[0053] <Drawing step and heat treatment step> The obtained undrawn yarn (artificial hair fiber before drawing step) 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 step at 115°C to obtain artificial hair fiber after the heat treatment step. The relaxation rate during the heat treatment was 0.50 to 0.99 times.

[0054] <Gear Processing Step> Using a gear machine ("NEW YAKI BRAID CRIMPING M / C-2.5mm" manufactured by SUNG JIN INDUSTRIAL CO., LTD.), gear processing was performed on the artificial hair fiber after the heat treatment step under the conditions of a gear pitch of 2.5 mm, preheating at 90°C, a gear roll temperature of 90°C, and a gear roll rotation speed of 1 m / min, to obtain a gear-processed artificial hair fiber.

[0055] (Examples 2 to 13, Comparative Examples 1 to 6) Artificial hair fibers were obtained in the same manner as in Example 1, except that the type of resin, the presence or absence of additives, the nozzle shape, the land length, the nozzle temperature, the cylinder temperature, the fineness, and the hollowness were changed.

[0056] In Examples 9 and 11 to 13, the following resins were used. In Examples 11 to 13, no additives were used, and only 0.5 parts by mass of carbon black was used. AS-based resin: acrylonitrile-styrene copolymer (GR-AT-6S manufactured by Denka Co., Ltd.) Polyester-based resin: polyethylene terephthalate (J125S manufactured by Mitsui Chemicals, Inc.) Polyamide-based resin: nylon 66 (Leona (registered trademark) 1500 manufactured by Asahi Kasei Chemicals Corporation) Polyolefin-based resin: polypropylene (Sumitomo Noblen (registered trademark) S131 manufactured by Sumitomo Chemical Co., Ltd.)

[0057] The artificial hair fibers thus produced were subjected to the tests and evaluations described below, and the results are shown in Tables 1 and 2.

[0058]

[0059]

[0060] (Hollowness) Artificial hair fibers were cut to an appropriate length, and the resulting bundle was wrapped in vinyl tape. The bundle was then cut perpendicular to the longitudinal direction with a utility knife to prepare a cross section, which was then observed. A cross-sectional photograph of the fiber was taken at 400x magnification using a laser microscope, and the area ratio of hollow portions in the cross section (hollowness) was measured. (Hollowness) = {(area enclosed by the inner surface) / (area enclosed by the outer surface)} x 100. The hollowness was calculated using a controller VK-X150 manufactured by Keyence Corporation. The hollowness was taken as the average value for 50 samples. In all of the examples and comparative examples, hollow portions were present in all of the artificial hair fibers.

[0061] (Hollow retention rate (stress 150N / cm ２ )) A plurality of artificial hair fibers (N number 20) were laid out and subjected to a pressure of 150 N / cm per unit area. ２ A weight of 1000g was placed on the bundle. Next, the artificial hair fiber was cut to an appropriate length, and the resulting bundle was wrapped in vinyl tape. The bundle was then cut perpendicular to the longitudinal direction with a cutter knife to prepare a cross section, which was then observed. Using a laser microscope, a cross-sectional photograph of the fiber was taken at 400x magnification to check whether the hollowness was maintained or whether the hollowness had been lost due to cracking at the joints or the like. The hollowness retention rate before and after applying stress to the artificial hair fiber bundle was calculated as the hollowness retention rate. (Hollowness retention rate) = {(Number of fibers that maintained a hollowness after applying stress) / (Number of fibers that maintained a hollowness before applying stress)} x 100

[0062] (Hollow retention rate (stress 200 N / cm ２ )) Weight per unit area 200N / cm ２ Other than changing to the hollow retention rate (stress 150 N / cm ２ ) and the hollow retention rate was calculated.

[0063] (Combability) Ten hair fiber processing technicians (with 5 or more years of work experience) combed an artificial hair fiber bundle for evaluation, 600 mm in length and 120 g in mass, through their fingers. The technicians rated the ease of combing the fiber bundle with their fingers as "easy to comb" or "difficult to comb" according to the following criteria: A: 0 technicians rated it as "difficult to comb" B: 1 to 4 technicians rated it as "difficult to comb" C: 5 to 8 technicians rated it as "difficult to comb" D: 9 or more technicians rated it as "difficult to comb"

[0064] 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

Claims

1. An artificial hair fiber, wherein the artificial hair fiber has a hollow portion extending in the longitudinal direction of the artificial hair fiber, and a fiber bundle for artificial hair consisting of a plurality of the artificial hair fibers has a tensile strength of 150 N / cm in the transverse direction. ２ When a stress of 1000 kJ / cm is applied, the hollow retention rate is 90% or more based on the state before the stress is applied.

2. 200 N / cm in the short direction to the artificial hair fiber bundle ２ 2. The fiber for artificial hair according to claim 1, wherein when a stress of 1000 kJ / cm is applied, the hollow retention rate is 80% or more based on the state before the stress is applied.

3. The artificial hair fiber according to claim 1, wherein the hollow ratio in the fiber cross section perpendicular to the longitudinal direction of the artificial hair fiber is 5 to 50%.

4. The artificial hair fiber according to claim 1, wherein the artificial hair fiber contains a vinyl chloride resin.

5. A hair accessory product comprising the artificial hair fiber according to any one of claims 1 to 4.

6. A hair accessory product according to claim 5, comprising a braid.

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