WO2024181538A1 - Artificial hair fiber, and hair accessory - Google Patents

Abstract

Provided is an artificial hair fiber having a tanδ peak of 88ºC or less in a dynamic viscoelasticity measurement at a frequency of 1 Hz in water. Also provided is a hair accessory comprising the aforementioned artificial hair fiber.

Description

Artificial hair fibers and hair accessories

The present invention relates to artificial hair fibers, hair accessories, etc.

Fibers for artificial hair (fibers used for artificial hair) can be used in hair accessories. Fibers for artificial hair have been developed to have an appearance similar to that of human hair (see, for example, Patent Document 1 below).

JP 2001-131824 A

After the artificial hair fibers are woven into a braided structure, the braided structure can be brought into contact with hot water to adjust the fiber orientation and provide a good appearance for the braided structure. In this case, hot water at a high temperature, such as 95°C, can be used, but when the temperature of the hot water drops over time, it may be difficult to continue using this hot water to provide a good appearance for the braided structure. For this reason, it is desirable to be able to provide a good appearance for the braided structure even when the temperature of the hot water drops over time, for example when using hot water at 75°C.

One aspect of the present invention aims to provide a fiber for artificial hair that can adequately maintain the appearance of the braided structure when the braided structure of the fiber for artificial hair is brought into contact with hot water at 75°C. Another aspect of the present invention aims to provide a hair accessory that includes such a fiber for artificial hair.

In some aspects, the present invention relates to the following [1] to [4] etc.
[1] A fiber for artificial hair, which has a tan δ peak of 88° C. or less in dynamic viscoelasticity measurement in water at a frequency of 1 Hz.
[2] The fiber for artificial hair according to [1], wherein the tan δ peak temperature is 50 to 88° C.
[3] The fiber for artificial hair according to [1] or [2], which contains a vinyl chloride polymer.
[4] A hair accessory comprising the artificial hair fiber according to any one of [1] to [3].

According to one aspect of the present invention, it is possible to provide a fiber for artificial hair that can adequately maintain the appearance of the braided structure when the braided structure of the fiber for artificial hair is brought into contact with hot water at 75°C. According to another aspect of the present invention, it is possible to provide a hair accessory that includes such a fiber for artificial hair.

The following describes in detail an embodiment of the present invention.

A numerical range "A or more" means A and a range exceeding A. A numerical range "A or less" means A and a range less than A. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a certain numerical range can be arbitrarily combined with the upper limit or lower limit of the numerical range of another stage. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more types. The content of each component in the composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. The term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. "(Meth)acrylic acid" means at least one of acrylic acid and the corresponding methacrylic acid. The same applies to other similar expressions such as "(meth)acrylate."

The fiber for artificial hair according to this embodiment has a tan δ peak (loss tangent peak) of 88°C or less in dynamic viscoelasticity measurement in water at a frequency of 1 Hz. The fiber for artificial hair according to this embodiment can be used as artificial hair (e.g., base fiber for artificial hair), and can also be used to obtain artificial hair. The fiber for artificial hair according to this embodiment may be a fiber after stretching treatment, or may be an unstretched fiber.

The braided structure (braided structure; braid) according to this embodiment is a braided structure of the artificial hair fiber according to this embodiment, and can be obtained by braiding the artificial hair fiber according to this embodiment. The braided structure according to this embodiment is not particularly limited, and examples include double braids, three braids, four braids, five braids, six braids, eight braids, etc.

The inventors have found that by using the temperature of the tan δ peak of the artificial hair fiber obtained by dynamic viscoelasticity measurement in water as an index, it is possible to adjust the appearance of the braided structure of the artificial hair fiber when the braided structure is brought into contact with warm water. According to the artificial hair fiber of this embodiment, it is possible to sufficiently adjust the appearance of the braided structure when the braided structure of the artificial hair fiber (e.g., a fiber bundle of the artificial hair fiber) is brought into contact with warm water at 75°C. For example, the appearance of the braided structure can be sufficiently adjusted (excellent shape and coherence can be obtained) by adjusting the orientation of the fibers by contacting the protruding fibers with warm water. For example, according to the artificial hair fiber of this embodiment, it is possible to obtain a state in which the fibers protruding from the braid before processing are aligned with the braiding direction of the braid after processing (a state in which the orientation of the fibers is adjusted by processing) using 75°C warm water in the evaluation method described in the examples described later.

The inventor speculates as follows about the reason why the appearance of the braided structure can be sufficiently adjusted when it is brought into contact with 75°C hot water. That is, the tan δ peak temperature of the artificial hair fiber obtained by dynamic viscoelasticity measurement in water correlates with the ease with which the artificial hair fiber softens when it is brought into contact with hot water. If the tan δ peak temperature is low, the fiber is more likely to soften in hot water and the orientation of the fiber is more easily adjusted. Therefore, the appearance of the braided structure can be sufficiently adjusted when it is brought into contact with 75°C hot water. However, the reason why the appearance of the braided structure can be sufficiently adjusted is not limited to the above.

In the artificial hair fiber according to this embodiment, it is sufficient that the appearance of the braided structure can be sufficiently adjusted when hot water of 75°C is used, and the appearance of the braided structure can be adjusted using hot water of other temperatures depending on the application. According to one aspect of the artificial hair fiber according to this embodiment, the appearance of the braided structure can be sufficiently adjusted when the braided structure of the artificial hair fiber is brought into contact with hot water of 95°C.

The artificial hair fiber according to this embodiment has a tan δ peak (hereinafter sometimes referred to as "peak P") of 88°C or less in dynamic viscoelasticity measurement at a frequency of 1 Hz in water, from the viewpoint of sufficiently adjusting the appearance of the braided structure when it is contacted with hot water at 75°C. When multiple tan δ peaks are confirmed in a temperature range of 88°C or less, the temperature of the peak with the largest tan δ can be used as the temperature of peak P. Peak P may be a peak derived from a vinyl chloride monomer unit in a vinyl chloride polymer. The temperature of peak P can be measured under the conditions described in the examples, and the dynamic viscoelasticity measurement can be performed in a measurement temperature range of 25 to 96°C at a heating rate of 1°C/min. The temperature of peak P can be adjusted depending on the type and content of the components contained in the artificial hair fiber, for example, the type and content of the plasticizer.

The temperature of Peak P (peak temperature) may be 87°C or less, 86°C or less, 85°C or less, 83°C or less, 80°C or less, 78°C or less, 77°C or less, 75°C or less, 70°C or less, 65°C or less, 60°C or less, 55°C or less, or 54°C or less, from the viewpoint of easily adjusting the appearance of the braided structure when it is contacted with warm water (e.g., warm water of 75°C). The temperature of Peak P may be 40°C or more, 45°C or more, 50°C or more, 54°C or more, 55°C or more, 60°C or more, 65°C or more, 70°C or more, 75°C or more, 77°C or more, 78°C or more, 80°C or more, 83°C or more, 85°C or more, or 86°C or more, from the viewpoint of easily obtaining an excellent feel of the artificial hair fiber. From these perspectives, the temperature of peak P may be 40 to 88°C, 40 to 80°C, 40 to 70°C, 40 to 60°C, 50 to 88°C, 50 to 80°C, 50 to 70°C, 50 to 60°C, 60 to 88°C, 60 to 80°C, 70 to 88°C, or 70 to 80°C.

The artificial hair fiber according to this embodiment may contain a polymer. The polymer may be a resin material. Examples of the polymer include vinyl chloride polymers, polyester polymers, polyamide polymers, polyolefin polymers, vinyl acetate polymers (ethylene-vinyl acetate copolymer (EVA) and the like), acrylonitrile polymers (acrylonitrile-butadiene rubber (NBR), acrylonitrile-butadiene-styrene polymer (ABS), acrylonitrile-styrene copolymer (AS) and the like), thermoplastic polyurethane (TPU), polyester thermoplastic elastomer (TPEE), methyl methacrylate-butadiene-styrene polymer (MBS), polymethyl methacrylate (PMMA), and the like. When a polymer that may be classified as a polymer other than vinyl chloride polymers has a vinyl chloride monomer unit, the polymer is defined as being classified as a vinyl chloride polymer. As the polymer, one type can be used alone or two or more types can be used in combination. For example, a vinyl chloride polymer and an acrylonitrile-styrene copolymer (AS) can be used in combination.

The artificial hair fiber according to this embodiment may contain a vinyl chloride polymer from the viewpoint of making it easier to adjust the appearance of the braided structure when it is brought into contact with warm water (e.g., warm water at 75°C). The vinyl chloride polymer is a polymer having vinyl chloride as a monomer unit (a polymer having a monomer unit of vinyl chloride). The vinyl chloride polymer can be obtained by bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc.

Vinyl chloride polymers include homopolymers of vinyl chloride (homopolymers, polyvinyl chloride), copolymers of vinyl chloride and other monomers, and mixtures of these may also be used. Examples of copolymers of vinyl chloride and other monomers include copolymers of vinyl chloride and vinyl esters (vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl propionate copolymer, etc.); copolymers of vinyl chloride and (meth)acrylic acid compounds ((meth)acrylic acid, (meth)acrylic acid esters, etc.) (vinyl chloride-butyl acrylate copolymer, vinyl chloride-2-ethylhexyl acrylate copolymer, etc.); copolymers of vinyl chloride and polyfunctional monomers described below; copolymers of vinyl chloride and olefins (vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, etc.); vinyl chloride-acrylonitrile copolymer, etc. The vinyl chloride polymer does not have to have monomer units of (meth)acrylic acid compounds.

The vinyl chloride polymer may contain a cross-linked vinyl chloride resin, and may contain a non-cross-linked vinyl chloride resin from the viewpoint of making it easier to maintain the appearance of the braided structure when it is contacted with warm water (e.g., warm water at 75°C). The "cross-linked" in cross-linked vinyl chloride resin means that the polymer chain has a branch point (e.g., a branch point where a side carbon chain branches from the main carbon chain) and is non-linear. The "non-cross-linked" in non-cross-linked vinyl chloride resin means that the polymer chain does not have a branch point (e.g., a branch point where a side carbon chain branches from the main carbon chain) and is linear.

Cross-linked vinyl chloride resins can be obtained by adding a polyfunctional monomer during the polymerization of vinyl chloride and polymerizing it. Examples of polyfunctional monomers include di(meth)acrylate compounds such as polyethylene glycol di(meth)acrylate and bisphenol A modified di(meth)acrylate. Cross-linked vinyl chloride resins may be a mixture of a gel component that has a cross-linked structure and is mainly composed of vinyl chloride monomer units, and a polyvinyl chloride component (a component composed of vinyl chloride monomer units). The gel component tends to be insoluble in tetrahydrofuran, and the polyvinyl chloride component tends to be soluble in tetrahydrofuran.

The content of the non-crosslinked vinyl chloride resin in the vinyl chloride polymer may be 50% by mass or more, more than 50% by mass, 70% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more based on the total mass of the vinyl chloride polymer, from the viewpoint of making it easier to maintain the appearance of the braided structure when it is contacted with hot water (e.g., hot water at 75°C). The vinyl chloride polymer may be in an embodiment that is substantially composed of only non-crosslinked vinyl chloride resin (substantially 100% by mass of the vinyl chloride polymer is non-crosslinked vinyl chloride resin).

From the viewpoint of easily adjusting the appearance of the braided structure when contacted with warm water (e.g., warm water of 75°C), the polymer may contain a non-crosslinked vinyl chloride resin with the following viscosity average polymerization degree. The viscosity average polymerization degree may be 100 or more, 300 or more, 400 or more, 500 or more, 600 or more, 700 or more, 800 or more, 900 or more, or 1000 or more. The viscosity average polymerization degree may be 3000 or less, 2500 or less, 2000 or less, 1500 or less, 1200 or less, or 1000 or less. From these viewpoints, the viscosity average polymerization degree may be 100 to 3000, 100 to 2000, 100 to 1500, 500 to 3000, 500 to 2000, 500 to 1500, 800 to 3000, 800 to 2000, or 800 to 1500. The viscosity average degree of polymerization can be calculated according to JIS K 6721 by measuring the specific viscosity of a solution obtained by dissolving 200 mg of non-crosslinked polyvinyl chloride resin in 50 mL of nitrobenzene in a thermostatic bath at 30°C using an Ubbelohde viscometer.

The content of vinyl chloride polymer in the polymer may be 50% by mass or more, more than 50% by mass, 70% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more based on the total mass of the polymer, from the viewpoint of making it easier to maintain the appearance of the braided structure when it is contacted with warm water (e.g., warm water at 75°C). The polymer may be in an embodiment that is substantially composed of only vinyl chloride polymer (substantially 100% by mass of the polymer is vinyl chloride polymer).

The polymer may include a mixture of vinyl chloride polymers and components capable of forming a polymer alloy with the vinyl chloride polymer. Examples of components capable of forming a polymer alloy with the vinyl chloride polymer include ethylene-vinyl acetate copolymer (EVA), acrylonitrile-butadiene rubber (NBR), thermoplastic polyurethane (TPU), polyester thermoplastic elastomer (TPEE), methyl methacrylate-butadiene-styrene polymer (MBS), acrylonitrile-butadiene-styrene polymer (ABS), acrylonitrile-styrene copolymer (AS), polymethyl methacrylate (PMMA), etc.

Examples of polyester polymers include polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polymethylene terephthalate, and glycol-modified polyethylene terephthalate.

Examples of polyamide polymers include nylon 6, nylon 66, nylon 11, nylon 12, nylon 6/10, and nylon 6/12.

Examples of polyolefin polymers include polyethylene and polypropylene.

As the polymer content or vinyl chloride polymer content, the content A may be in the following ranges based on the total mass of the artificial hair fiber. From the viewpoint of easily obtaining an excellent feel of the artificial hair fiber, the content A may be 50% by mass or more, more than 50% by mass, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 72% by mass or more, 75% by mass or more, 78% by mass or more, 80% by mass or more, 82% by mass or more, 85% by mass or more, or 88% by mass or more. From the viewpoint of easily adjusting the appearance of the braided structure when contacted with warm water (e.g., warm water at 75°C), the content A may be 90% by mass or less, 89% by mass or less, 88% by mass or less, 85% by mass or less, 82% by mass or less, 80% by mass or less, 78% by mass or less, or 75% by mass or less. From these viewpoints, the content A may be 50 to 90% by mass, 50 to 85% by mass, 50 to 80% by mass, 50 to 75% by mass, 70 to 90% by mass, 70 to 85% by mass, 70 to 80% by mass, 70 to 75% by mass, 80 to 90% by mass, 80 to 85% by mass, or 85 to 90% by mass.

The artificial hair fiber according to this embodiment may contain a plasticizer. Examples of the plasticizer include epoxy-based plasticizers, phthalic acid-based plasticizers, isophthalic acid-based plasticizers, terephthalic acid-based plasticizers, adipic acid-based plasticizers (excluding those that fall under the category of polyester-based plasticizers), polyester-based plasticizers, phosphoric acid-based plasticizers, trimellitic acid-based plasticizers, and benzoic acid-based plasticizers. Specific examples of plasticizers include epoxidized soybean oil, epoxidized linseed oil, diisonyl phthalate (DINP), diheptyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate (n-DOP), diisodecyl phthalate (DIDP), phthalate-propylene glycol polyester, benzyl butyl phthalate (BBP), di-2-ethylhexyl isophthalate (DOIP), and di-2-ethylhexyl terephthalate (DOTP). , diisononyl adipate (DINA), di-2-ethylhexyl adipate (DOA), diisodecyl adipate, benzyl octyl adipate (BOA), adipic acid-propylene glycol polyester, adipic acid-butylene glycol polyester, tricresyl phosphate (TCP), diphenyl cresyl phosphate (DPCP), tri-2-ethylhexyl trimellitate (TOTM), oxydiethylene dibenzoate, etc. As the plasticizer, one type can be used alone or two or more types can be used in combination, for example, epoxidized soybean oil can be used in combination with other plasticizers.

The plasticizer may contain at least one selected from the group consisting of epoxy-based plasticizers, phthalic acid-based plasticizers, terephthalic acid-based plasticizers, adipic acid-based plasticizers, and polyester-based plasticizers, from the viewpoint of making it easier to maintain the appearance of the woven structure when it is brought into contact with warm water (e.g., warm water at 75°C), and may contain at least one selected from the group consisting of epoxidized soybean oil, diisonyl phthalate, di-2-ethylhexyl terephthalate, and diisononyl adipate.

The plasticizer content may be within the following ranges based on the total mass of the artificial hair fiber. From the viewpoint of making it easier to adjust the appearance of the braided structure when contacted with warm water (e.g., warm water at 75°C), the plasticizer content may be 2.0 mass% or more, 3.0 mass% or more, 4.0 mass% or more, 5.0 mass% or more, 6.0 mass% or more, 7.0 mass% or more, 8.0 mass% or more, 9.0 mass% or more, 10.0 mass% or more, 12.0 mass% or more, 15.0 mass% or more, 18.0 mass% or more, or 20.0 mass% or more. From the viewpoint of easily obtaining an excellent feel of the artificial hair fiber, the content of the plasticizer may be 30.0% by mass or less, 25.0% by mass or less, 20.0% by mass or less, 18.0% by mass or less, 15.0% by mass or less, 12.0% by mass or less, 10.0% by mass or less, 9.0% by mass or less, 8.0% by mass or less, 7.0% by mass or less, 6.0% by mass or less, or 5.0% by mass or less. From these viewpoints, the content of the plasticizer may be 2.0 to 30.0% by mass, 2.0 to 20.0% by mass, 2.0 to 10.0% by mass, 2.0 to 6.0% by mass, 4.0 to 30.0% by mass, 4.0 to 20.0% by mass, 4.0 to 10.0% by mass, 4.0 to 6.0% by mass, 5.0 to 30.0% by mass, 5.0 to 20.0% by mass, 5.0 to 10.0% by mass, 10.0 to 30.0% by mass, or 15.0 to 30.0% by mass.

The plasticizer content may be within the following ranges per 100 parts by mass of polymer or 100 parts by mass of vinyl chloride polymer. From the viewpoint of making it easier to adjust the appearance of the braided structure when contacted with warm water (e.g., warm water at 75°C), the plasticizer content may be 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, 8.0 parts by mass or more, 9.0 parts by mass or more, 10.0 parts by mass or more, 12.0 parts by mass or more, 15.0 parts by mass or more, 18.0 parts by mass or more, 20.0 parts by mass or more, 22.0 parts by mass or more, 25.0 parts by mass or more, 28.0 parts by mass or more, or 30.0 parts by mass or more. From the viewpoint of easily obtaining an excellent touch of the artificial hair fiber, the content of the plasticizer may be 50.0 parts by mass or less, 45.0 parts by mass or less, 40.0 parts by mass or less, 35.0 parts by mass or less, 30.0 parts by mass or less, 28.0 parts by mass or less, 25.0 parts by mass or less, 22.0 parts by mass or less, 20.0 parts by mass or less, 18.0 parts by mass or less, 15.0 parts by mass or less, 12.0 parts by mass or less, 10.0 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, 7.0 parts by mass or less, 6.0 parts by mass or less, or 5.0 parts by mass or less. From these viewpoints, the content of the plasticizer may be 2.0 to 50.0 parts by mass, 2.0 to 30.0 parts by mass, 2.0 to 10.0 parts by mass, 2.0 to 8.0 parts by mass, 4.0 to 50.0 parts by mass, 4.0 to 30.0 parts by mass, 4.0 to 10.0 parts by mass, 4.0 to 8.0 parts by mass, 6.0 to 50.0 parts by mass, 6.0 to 30.0 parts by mass, 6.0 to 10.0 parts by mass, 10.0 to 50.0 parts by mass, or 20.0 to 50.0 parts by mass.

The artificial hair fiber according to this embodiment may contain components other than those mentioned above (polymers, plasticizers, etc.). Such components include heat stabilizers, lubricants, antistatic agents, flame retardants, flame retardant assistants, UV absorbers, light stabilizers, fluorescent agents, antioxidants, etc.

Heat stabilizers include Ca-Zn-based heat stabilizers, hydrotalcite-based heat stabilizers, tin-based heat stabilizers, and β-diketone-based heat stabilizers.

Ca-Zn heat stabilizers include zinc stearate, calcium stearate, zinc 12-hydroxystearate, calcium 12-hydroxystearate, etc.

Hydrotalcite-based heat stabilizers include complex salt compounds made of magnesium and/or alkali metals and aluminum or zinc, complex salt compounds made of magnesium and aluminum, and compounds obtained by dehydrating the water of crystallization of these complex salt compounds.

Tin-based heat stabilizers include mercaptotin-based heat stabilizers such as dimethyltin mercapto, dimethyltin mercaptide, dibutyltin mercapto, dioctyltin mercapto, dioctyltin mercapto polymer, and dioctyltin mercaptoacetate; maleate-tin-based heat stabilizers such as dimethyltin maleate, dibutyltin maleate, dioctyltin maleate, and dioctyltin maleate polymer; and laurate-tin-based heat stabilizers such as dimethyltin laurate, dibutyltin laurate, and dioctyltin laurate.

Beta-diketone heat stabilizers include stearoylbenzoylmethane, dibenzoylmethane, etc.

Lubricants include metal soap-based lubricants, higher fatty acid-based lubricants, ester-based lubricants, higher alcohol-based lubricants, etc.

Metal soap-based lubricants include metal soaps, such as stearates, laurates, palmitates, and oleates of Na, Mg, Al, Ca, and Ba.

Higher fatty acid lubricants include saturated fatty acids such as stearic acid, palmitic acid, myristic acid, lauric acid, and capric acid; unsaturated fatty acids such as oleic acid; and mixtures of these.

Ester-based lubricants include ester-based lubricants consisting of alcohol and fatty acid; pentaerythritol-based lubricants such as monoesters, diesters, triesters, tetraesters, or mixtures of these, of pentaerythritol or dipentaerythritol with higher fatty acids; and montanic acid wax-based lubricants such as esters of montanic acid and higher alcohols (stearyl alcohol, palmityl alcohol, myristyl alcohol, lauryl alcohol, oleyl alcohol, etc.).

Examples of higher alcohol lubricants include stearyl alcohol, palmityl alcohol, myristyl alcohol, lauryl alcohol, and oleyl alcohol.

The monofilament fineness of the artificial hair fiber according to this embodiment may be in the following ranges after the stretching process. The monofilament fineness may be 20 decitex or more, 30 decitex or more, 40 decitex or more, or 50 decitex or more. The monofilament fineness may be 100 decitex or less, 90 decitex or less, 80 decitex or less, or 70 decitex or less. From these viewpoints, the monofilament fineness may be 20 to 100 decitex.

The method for producing artificial hair fibers according to this embodiment may include a spinning process for spinning a composition containing the components of artificial hair fibers (polymers, plasticizers, etc.). In the spinning process, the composition containing the components of artificial hair fibers (polymers, plasticizers, etc.) can be melt spun (melt deformed).

The method for producing artificial hair fibers according to this embodiment may include a kneading step in which a composition containing the components of the artificial hair fibers (polymer, plasticizer, etc.) is melt-kneaded prior to the spinning step. As an apparatus for melt-kneading, various general kneading machines can be used. Examples of kneading machines include single-screw extruders, twin-screw extruders, rolls, Banbury mixers, kneaders, etc.

The method for producing artificial hair fibers according to this embodiment may include a drawing process after the spinning process in which the yarn (undrawn yarn) obtained in the spinning process is drawn.

The stretching ratio in the stretching step may be 1.5 times or more, or 2.0 times or more, from the viewpoint of facilitating the development of fiber strength. The stretching ratio may be 5.0 times or less, or 4.0 times or less, from the viewpoint of preventing thread breakage during the stretching process. From these viewpoints, the stretching ratio may be 1.5 to 5.0 times.

The drawing process may be performed by a two-step method in which the undrawn yarn is once wound onto a bobbin and then drawn in a step not subsequent to the spinning process, or by a direct spinning drawing method in which the undrawn yarn is drawn in a step subsequent to the spinning process without being wound onto a bobbin. The drawing process may be performed by a one-stage drawing method in which the yarn is drawn to the desired draw ratio in one go, or by a multi-stage drawing method in which the yarn is drawn to the desired draw ratio by two or more draws.

The temperature for the stretching process may be 80 to 120°C. If the temperature is 80°C or higher, it is easier to ensure sufficient fiber strength and thread breakage is less likely to occur. If the temperature is 120°C or lower, it is easier to obtain a favorable fiber feel.

The method for producing artificial hair fibers according to this embodiment may include a heat treatment step in which the yarn (drawn yarn) obtained in the drawing step is heat treated (annealed) after the drawing step. By carrying out the heat treatment step, the thermal shrinkage rate of the drawn yarn can be reduced.

The heat treatment temperature may be 100°C or higher, or 120°C or higher. The heat treatment temperature may be 200°C or lower, or 150°C or lower. From these viewpoints, the heat treatment temperature may be 100 to 200°C. The heat treatment may be performed continuously after the stretching treatment, or may be performed after a period of time has elapsed after the film has been wound up.

The manufacturing method for artificial hair fibers according to this embodiment may include a gear processing step in which the artificial hair fibers are subjected to gear processing (shaping processing). The gear processing is a process in which the fibers are passed between two meshing high-temperature gears to cause crimping. The gear processing step can be performed after the spinning step, and may be performed after the above-mentioned heat treatment step. In the gear processing step, the gear material, gear waveform, gear fraction, etc. are not particularly limited.

The method for producing fibers for artificial hair according to this embodiment may include a hot water treatment step in which the fibers for artificial hair are brought into contact with hot water (e.g., immersed). The hot water treatment step can be carried out after the spinning step, may be carried out after the heat treatment step described above, or may be carried out after the gear processing step described above. The temperature of the hot water may be 70 to 100°C, 75 to 100°C, 70 to 95°C, 75 to 95°C, 70°C or higher but lower than 95°C, 75°C or higher but lower than 95°C, 70 to 90°C, 75 to 90°C, 70 to 80°C, or 75 to 80°C.

The hair accessory according to this embodiment comprises the artificial hair fiber according to this embodiment. The hair accessory according to this embodiment is an article that can be attached to and detached from the head. The hair accessory according to this embodiment may be in a form consisting of the artificial hair fiber according to this embodiment (for example, a fiber bundle of the artificial hair fiber), or may be in a form comprising the artificial hair fiber according to this embodiment and a member different from the artificial hair fiber. Examples of hair accessories include wigs, hair toupees, hair pieces, braids, extension hair, false hair, etc.

The present invention will be explained in detail below with reference to examples, but the present invention is not limited to these examples.

<Preparation of artificial hair fibers>
A vinyl chloride resin composition was obtained by mixing a polymer (manufactured by Taiyo Vinyl Co., Ltd., trade name: TH1000, non-crosslinked vinyl chloride resin, vinyl chloride homopolymer, viscosity average degree of polymerization: 1000), a plasticizer (manufactured by Chang Chun Petrochemical Co. Ltd., trade name: Epoxidized Soybean Oil/ESBO/ESBOD, epoxidized soybean oil), and additives (heat stabilizer, etc.) in a blender. Pellets were produced by compounding this vinyl chloride resin composition using an extruder with a diameter of 65 mm at a cylinder temperature of 130 to 170°C. The pellets were melt-spun using an extruder with a diameter of 40 mm to obtain fiber A. The cylinder temperature during melt spinning was 150 to 190°C. Fiber A was heat-treated for about 0.5 to 1.5 seconds in a heating cylinder installed directly below the nozzle to obtain fiber B with an average fineness of 140 dtex. Fiber B was stretched 300% in an air atmosphere at 100°C, and then heat-shrunk in an air atmosphere at 120°C until the entire fiber length was 80% of the length before treatment to obtain an artificial hair fiber with an average fineness of 56 dtex. The contents of polymer and plasticizer based on the total mass of the artificial hair fiber are shown in Table 1. The content of additives is the remainder obtained by subtracting the contents of polymer and plasticizer from the total mass of the artificial hair fiber.

<Preparation of fiber bundle>
The above-mentioned artificial hair fiber was shaped using a gear machine (NEW YAKI BRAID CRIMPING M/C-2.5mm/SUNG JIN INDUSTRIAL CO., LTD.) under the conditions of a gear pitch of 2.5 mm, preheating at 80°C, a gear roll temperature of 80°C, and a gear roll rotation speed of 1 m/min. The fibers were then bundled to obtain a fiber bundle A having a length of 400 mm and a mass of 5.1 g.

The above-mentioned artificial hair fibers were shaped using a gear machine (NEW YAKI BRAID CRIMPING M/C-2.5mm/SUNG JIN INDUSTRIAL CO., LTD.) under the following conditions: gear pitch 2.5mm, preheating 90°C, gear roll temperature 90°C, and gear roll rotation speed 1m/min. The fibers were then bundled to obtain fiber bundle B with a length of 600mm and a mass of 120g.

<Temperature measurement of tan δ peak>
Four artificial hair fibers were taken out from the above-mentioned fiber bundle A. Next, the four fibers were arranged in a state where adjacent fibers were in contact with each other, and fixed with a jig, and then the fibers were immersed in a container containing water. Next, the dynamic viscoelasticity of the fibers in water was measured using a measuring device (manufactured by TA instruments, product name: RSA-G2) to obtain the peak temperature of the tan δ peak. Using the underwater measurement unit of this measuring device, the measurement conditions were a temperature rise rate of 1°C/min, a distance between chucks of 10 mm, a frequency of 1 Hz, a strain of 0.1%, a tensile mode, and a measurement temperature range of 25 to 96°C. The temperature of the water in the container was raised at a temperature rise rate of 1°C/min in a measurement temperature range of 25 to 96°C. The measurement results of the peak temperature are shown in Table 1. In Examples 1 to 4 and Comparative Examples 1 and 2, one peak was confirmed in the temperature range of 25 to 96°C.

<Appearance Evaluation>
A braided structure was prepared using the above-mentioned fiber bundle A having a length of 400 mm and a mass of 5.1 g, and then the braided structure was immersed in water (warm water) at 95°C or 75°C for 15 seconds. Next, the braided structure was taken out of the water, and the water was wiped off by gently rubbing the surface of the braided structure three times. Then, the braided structure was left at room temperature (25°C) for 24 hours or more to dry naturally, and the appearance of the braided structure was visually observed. When the braid condition was good, it was judged as "A", and when the braid condition was poor, it was judged as "B". When the fibers protruding from the braid before the treatment were aligned with the braiding direction after the treatment (the direction of the fibers was aligned by the treatment), it was judged to be in a good state. The results are shown in Table 1.

<Tactile sensation>
The above-mentioned fiber bundle B was judged into two ranks, "firm" and "not firm", based on the feel (firm texture felt when touching fiber bundle B as if compressing it with the palm) by 10 hair fiber processing technicians (with 5 or more years of practical experience). A case in which 9 or more technicians judged it to have firmness was judged as "A", and a case in which 8 or less technicians judged it to have firmness was judged as "B". The results are shown in Table 1.

Claims (4)

A fiber for artificial hair that has a tan δ peak of 88°C or less when dynamic viscoelasticity is measured in water at a frequency of 1 Hz. The artificial hair fiber according to claim 1, wherein the tan δ peak temperature is 50 to 88°C. The artificial hair fiber according to claim 1, which contains a vinyl chloride polymer. A hair accessory comprising the artificial hair fiber according to any one of claims 1 to 3.