JP7697015B2 - Artificial hair fibers, artificial hair fiber bundles and hair accessories - Google Patents

Description

The present invention relates to artificial hair fibers, fiber bundles for artificial hair, hair decoration products, etc.

Vinyl chloride polymer fibers obtained by spinning vinyl chloride polymers have excellent flexibility and are widely used as artificial hair fibers that make up hair accessory products. However, vinyl chloride polymer fibers are not suitable for styles that require volume in artificial hair applications because the specific gravity of the vinyl chloride polymer is large. In order to reduce the specific gravity of vinyl chloride polymer fibers, a method has been proposed in which an aromatic vinyl polymer, which has a smaller specific gravity than vinyl chloride polymer, is blended (see, for example, Patent Documents 1 and 2 below).

International Publication No. 2006/038447 International Publication No. 2019/181868

The inventors came up with the idea of improving the volume of artificial hair fibers by subjecting the fibers to a gear processing treatment to cause them to curl when producing hair accessory products using the fibers for artificial hair. However, when using artificial hair fibers containing an aromatic vinyl polymer, there is a problem that the volume is not sufficiently improved, limiting the styles that can be produced.

One aspect of the present invention provides a fiber for artificial hair that can be subjected to gear processing to obtain artificial hair with excellent volume (specific volume). Another aspect of the present invention provides a fiber bundle for artificial hair that uses the fiber for artificial hair. Another aspect of the present invention provides a hair accessory product that uses the fiber bundle for artificial hair.

In some aspects, the present invention relates to the following [1] to [9] etc.
[1] A fiber for artificial hair, comprising a vinyl chloride polymer and an aromatic vinyl polymer, and having a heat shrinkage rate of 7% or more at 100°C.
[2] The fiber for artificial hair according to [1], wherein the heat shrinkage rate is 7 to 25%.
[3] The fiber for artificial hair according to [1] or [2], wherein the content of the vinyl chloride polymer is 60 to 95% by mass, and the content of the aromatic vinyl polymer is 5 to 40% by mass.
[4] The fiber for artificial hair according to any one of [1] to [3], wherein the aromatic vinyl polymer has a styrene-based compound and (meth)acrylonitrile as monomer units.
[5] The artificial hair fiber according to [4], wherein the styrene-based compound contains styrene.
[6] The fiber for artificial hair according to [4] or [5], wherein the proportion of the monomer units of the styrene-based compound is 74 to 88 mass% and the proportion of the monomer units of the (meth)acrylonitrile is 12 to 26 mass% based on the entirety of the aromatic vinyl polymer.
[7] A fiber bundle for artificial hair, comprising the fiber for artificial hair according to any one of [1] to [6].
[8] The fiber bundle for artificial hair described in [7], further comprising fibers different from the fibers for artificial hair.
[9] A hair accessory product comprising the artificial hair fiber bundle according to [7] or [8].

According to one aspect of the present invention, it is possible to provide a fiber for artificial hair, which can be subjected to gear processing to obtain artificial hair with excellent volume (specific volume). According to another aspect of the present invention, it is possible to provide a fiber bundle for artificial hair using the fiber for artificial hair. According to another aspect of the present invention, it is possible to provide a hair accessory product using the fiber bundle for artificial hair. According to another aspect of the present invention, it is possible to provide artificial hair or an application of the fiber to the manufacture thereof. According to another aspect of the present invention, it is possible to provide a hair accessory product or an application of the fiber to the manufacture thereof.

The following describes in detail the form for implementing the present invention. Note that the present invention is not limited to the embodiment described below.

In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of the numerical range of another stage. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values shown in the examples. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. "(Meth)acrylonitrile" means at least one of acrylonitrile and the corresponding methacrylonitrile. The same applies to other similar expressions such as "(meth)acrylic acid".

The artificial hair fiber according to this embodiment contains a vinyl chloride polymer and an aromatic vinyl polymer (excluding polymers that fall under the category of vinyl chloride polymer). The artificial hair fiber according to this embodiment has a heat shrinkage rate of 7% or more at 100°C. The artificial hair fiber according to this embodiment is composed of a resin composition (fibrous resin composition) that contains a vinyl chloride polymer and an aromatic vinyl polymer and has a heat shrinkage rate of 7% or more at 100°C. The resin composition according to this embodiment is a resin composition for artificial hair that contains a vinyl chloride polymer and an aromatic vinyl polymer and has a heat shrinkage rate of 7% or more at 100°C.

According to the fiber for artificial hair according to this embodiment, it is possible to obtain artificial hair with excellent volume (specific volume) by performing gear processing. For example, in the evaluation method described in the examples below, a specific volume exceeding 7.0 cc/g can be obtained by performing gear processing (processing in the length direction of the fiber, depth of the gear wave groove: 2.5 mm, gear pitch: 2.5 mm, surface temperature: 90°C, processing speed: 1.0 m/min) on the fiber for artificial hair. It is presumed that the volume is improved because the fiber containing vinyl chloride polymer and aromatic vinyl polymer has a high thermal shrinkage rate, and the fiber is likely to shrink due to the surface temperature of the gear when the fiber is subjected to gear processing. However, the factor for improving the volume is not limited to this factor.

Gear processing is a process in which fibers (fiber bundles, etc.) are crimped by passing them between two meshing high-temperature gears. In the gear processing of the artificial hair fiber according to this embodiment, the gear material, gear waveform, gear fraction, etc. are not particularly limited. The crimp wave shape can change depending on the fiber material, fineness, pressure conditions between the gears, etc., but in this embodiment, the crimp wave shape can be controlled by the depth of the groove of the gear waveform, the surface temperature of the gear, the processing speed, etc. There are no particular limitations on these processing conditions, but the depth of the groove of the gear waveform may be 0.2 to 6 mm or 0.5 to 5 mm, the surface temperature of the gear may be 50 to 110°C or 60 to 100°C, and the processing speed may be 0.5 to 10 m/min or 1.0 to 8.0 m/min.

In conventional artificial hair fibers, when the fibers are frizzy, combability may decrease. In contrast, according to one aspect of the artificial hair fiber of this embodiment, it is possible to obtain excellent combability while obtaining a good sense of volume. For example, the resistance can be reduced to 300 gf or less (e.g., 250 gf or less) in the evaluation method described in the examples below.

Fibers for artificial hair are required to suppress fiber breakage (yarn breakage) during melt spinning and other processes, and may be required to have excellent spinnability. In contrast, one aspect of the fiber for artificial hair according to this embodiment makes it possible to obtain excellent spinnability, and for example, in the evaluation method described in the examples below, yarn breakage can be suppressed to three or less times.

The heat shrinkage rate of the artificial hair fiber according to this embodiment at 100°C is 7% or more from the viewpoint of obtaining an excellent sense of volume. The heat shrinkage rate may be 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 15% or more, 18% or more, 19% or more, 20% or more, 22% or more, 23% or more, 25% or more, or 28% or more from the viewpoint of easily obtaining an excellent sense of volume. The heat shrinkage rate may be 40% or less, 35% or less, 30% or less, 28% or less, 25% or less, 23% or less, 22% or less, 20% or less, 19% or less, 18% or less, 15% or less, 12% or less, 11% or less, 10% or less, 9% or less, or 8% or less from the viewpoint of easily obtaining an excellent combability. From these perspectives, the heat shrinkage percentage may be 7 to 40%, 7 to 30%, 8 to 30%, 8 to 28%, 10 to 28%, 12 to 28%, 15 to 28%, 20 to 28%, 22 to 28%, 7 to 25%, 8 to 25%, 8 to 22%, 8 to 20%, 8 to 15%, 10 to 25%, 15 to 25%, or 20 to 25%.

The heat shrinkage rate of the artificial hair fiber according to this embodiment at 100°C can be measured by the method described in the Examples below. The heat shrinkage rate can be adjusted by the heating temperature of the heat treatment (e.g., heat treatment after stretching) after spinning when obtaining the artificial hair fiber; the type or content of the monomer unit of the vinyl chloride polymer; the type or content of the monomer unit of the aromatic vinyl polymer, etc. The inventors found that the heat shrinkage rate is likely to increase by reducing the heating temperature of the heat treatment, and found that the heat shrinkage rate of the artificial hair fiber obtained at a heating temperature of 120°C as in the Examples of Patent Documents 1 and 2 is not sufficiently high (see Comparative Examples below), and then found that it is easy to obtain artificial hair fibers with a large heat shrinkage rate at a heating temperature of less than 120°C (e.g., 110°C or less).

The fiber for artificial hair according to this embodiment can be used to obtain artificial hair. The fiber for artificial hair according to this embodiment may be a fiber after a drawing treatment, or an undrawn fiber.

The monofilament fineness of the artificial hair fiber according to this embodiment may be in the following ranges. The monofilament fineness may be 10 decitex or more, 20 decitex or more, 30 decitex or more, 40 decitex or more, 50 decitex or more, or 60 decitex or more. The monofilament fineness may be 100 decitex or less, 90 decitex or less, 80 decitex or less, 70 decitex or less, or 60 decitex or less. From these viewpoints, the monofilament fineness may be 10 to 100 decitex, 30 to 90 decitex, or 50 to 70 decitex.

The artificial hair fiber according to this embodiment contains a vinyl chloride polymer (e.g., a vinyl chloride resin). A vinyl chloride polymer is a polymer having vinyl chloride as a monomer unit (a polymer having a structural unit derived from vinyl chloride). A vinyl chloride polymer may be a homopolymer of vinyl chloride or a copolymer of vinyl chloride. A copolymer of vinyl chloride is a polymer of vinyl chloride and another compound (a compound other than vinyl chloride).

Examples of vinyl chloride 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 acrylic esters, such as vinyl chloride-butyl acrylate copolymer and vinyl chloride-2-ethylhexyl acrylate copolymer; copolymers of vinyl chloride and olefins, such as vinyl chloride-ethylene copolymer and vinyl chloride-propylene copolymer; and vinyl chloride-acrylonitrile copolymer.

From the viewpoint of easily obtaining excellent volume, combability and spinnability, the vinyl chloride polymer may comprise at least one selected from the group consisting of vinyl chloride homopolymer, vinyl chloride-ethylene copolymer and vinyl chloride-vinyl acetate copolymer, and may comprise vinyl chloride homopolymer.

The vinyl chloride polymer can be produced by emulsion polymerization, bulk polymerization, suspension polymerization, etc. From the viewpoint of the initial colorability of the fiber, the vinyl chloride polymer may be a polymer produced by suspension polymerization.

The content of vinyl chloride polymer is more than 0% by mass and less than 100% by mass based on the total mass of the artificial hair fiber or the total amount of vinyl chloride polymer and aromatic vinyl polymer, and may be in the following ranges: From the viewpoint of easily obtaining an excellent sense of volume, the content of vinyl chloride polymer may be 98% by mass or less, 96% by mass or less, 95% by mass or less, less than 95% by mass, 90% by mass or less, 85% by mass or less, 83% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, or 65% by mass or less. From the viewpoint of easily obtaining excellent combability and spinnability, the content of the vinyl chloride polymer may be 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 83% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, more than 95% by mass, or 96% by mass or more. From these viewpoints, the content of the vinyl chloride polymer may be 40 to 98% by mass, 50 to 96% by mass, 60 to 96% by mass, 65 to 96% by mass, 70 to 96% by mass, 60 to 95% by mass, 65 to 90% by mass, 65 to 80% by mass, or 65 to 70% by mass.

The artificial hair fiber according to this embodiment contains an aromatic vinyl polymer (e.g., an aromatic vinyl resin). The aromatic vinyl polymer is a polymer having an aromatic vinyl compound as a monomer unit (a polymer having a structural unit derived from an aromatic vinyl compound). Examples of aromatic vinyl compounds include styrene-based compounds, vinyl toluene, vinyl naphthalene, vinyl anthracene, and the like. The aromatic vinyl polymer may have a styrene-based compound as a monomer unit from the viewpoint of easily obtaining excellent volume, combability, and spinnability.

The styrene-based compound may contain at least one selected from the group consisting of styrene and styrene derivatives. Examples of styrene derivatives include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butylstyrene, and chlorostyrene. The styrene-based compound may contain styrene from the viewpoint of easily obtaining excellent volume, combability, and spinnability.

The aromatic vinyl polymer may be a homopolymer of an aromatic vinyl compound, or a copolymer of an aromatic vinyl compound (e.g., an aromatic vinyl copolymer resin). The aromatic vinyl copolymer may be a copolymer having multiple types of aromatic vinyl compounds as monomer units, or a copolymer having an aromatic vinyl compound and a compound other than the aromatic vinyl compound as monomer units.

Examples of compounds other than aromatic vinyl compounds include (meth)acrylonitrile, vinyl compounds (excluding compounds corresponding to styrene compounds), maleic anhydride, etc. Examples of vinyl compounds include (meth)acrylic acid; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The aromatic vinyl polymer does not have to have a (meth)acrylic acid ester as a monomer unit (it does not have to have at least one selected from the group consisting of acrylic acid esters and methacrylic acid esters as a monomer unit). As the aromatic vinyl polymer, it is possible to use a polymer that does not have vinyl chloride as a monomer unit, and a polymer that does not have a halogen-containing compound as a monomer unit may be used.

From the viewpoint of easily obtaining excellent volume, combability, and spinnability, the aromatic vinyl polymer may have a styrene-based compound and (meth)acrylonitrile as monomer units (may have monomer units of a styrene-based compound and at least one selected from the group consisting of monomer units of acrylonitrile and monomer units of methacrylonitrile), may have styrene and (meth)acrylonitrile as monomer units (may have monomer units of styrene and at least one selected from the group consisting of monomer units of acrylonitrile and monomer units of methacrylonitrile), may have styrene and acrylonitrile as monomer units.

The proportion of the monomer units of the styrene-based compound may be in the following ranges based on the entire aromatic vinyl polymer or on the total amount of the monomer units of the styrene-based compound and the monomer units of (meth)acrylonitrile (the total amount of the monomer units of the styrene-based compound, the monomer units of acrylonitrile, and the monomer units of methacrylonitrile). From the viewpoint of easily obtaining an excellent sense of volume, the proportion of the monomer units of the styrene-based compound may be 50% by mass or more, more than 50% by mass, 60% by mass or more, more than 60% by mass, 65% by mass or more, 68% by mass or more, 69% by mass or more, more than 69% by mass, 70% by mass or more, more than 70% by mass, 74% by mass or more, 75% by mass or more, 80% by mass or more, 82% by mass or more, 85% by mass or more, more than 85% by mass, 86% by mass or more, or 90% by mass or more. From the viewpoint of easily obtaining excellent combability and spinnability, the proportion of monomer units of the styrene-based compound may be less than 100% by mass, 95% by mass or less, 90% by mass or less, 88% by mass or less, less than 88% by mass, 86% by mass or less, 85% by mass or less, less than 85% by mass, 82% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, less than 70% by mass, 69% by mass or less, less than 69% by mass, or 68% by mass or less. From these viewpoints, the ratio of the monomer unit of the styrene-based compound may be 50% by mass or more and less than 100% by mass, 60 to 95% by mass, 68 to 90% by mass, 68 to 86% by mass, 68 to 82% by mass, 68 to 75% by mass, 68 to 70% by mass, 70 to 90% by mass, 75 to 90% by mass, 82 to 90% by mass, 86 to 90% by mass, 70 to 86% by mass, 70 to 82% by mass, 70 to 75% by mass, 75 to 86% by mass, 82 to 86% by mass, 75 to 82% by mass, 50 to 82% by mass, 60 to 82% by mass, 82 to 95% by mass, 74 to 88% by mass, or 74% by mass or more and less than 88% by mass.

The proportion of (meth)acrylonitrile monomer units (proportion of the total amount of acrylonitrile monomer units and methacrylonitrile monomer units) may be in the following range based on the entire aromatic vinyl polymer, or based on the total amount of styrene-based compound monomer units and (meth)acrylonitrile monomer units (total amount of styrene-based compound monomer units, acrylonitrile monomer units, and methacrylonitrile monomer units). From the viewpoint of easily obtaining excellent combability and spinnability, the proportion of (meth)acrylonitrile monomer units may be more than 0% by mass, 5% by mass or more, 10% by mass or more, 12% by mass or more, more than 12% by mass, 14% by mass or more, 15% by mass or more, more than 15% by mass, 18% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, more than 30% by mass, 31% by mass or more, more than 31% by mass, or 32% by mass or more. From the viewpoint of suppressing the color of the artificial hair fiber, the proportion of (meth)acrylonitrile monomer units may be 50% by mass or less, less than 50% by mass, 40% by mass or less, less than 40% by mass, 35% by mass or less, 32% by mass or less, 31% by mass or less, less than 31% by mass, 30% by mass or less, less than 30% by mass, 26% by mass or less, 25% by mass or less, 20% by mass or less, 18% by mass or less, 15% by mass or less, less than 15% by mass, 14% by mass or less, or 10% by mass or less. From these viewpoints, the ratio of the monomer unit of (meth)acrylonitrile may be more than 0% by mass and not more than 50% by mass, 5 to 40% by mass, 10 to 32% by mass, 14 to 32% by mass, 18 to 32% by mass, 25 to 32% by mass, 30 to 32% by mass, 10 to 30% by mass, 10 to 25% by mass, 10 to 18% by mass, 10 to 14% by mass, 14 to 30% by mass, 18 to 30% by mass, 25 to 30% by mass, 14 to 25% by mass, 14 to 18% by mass, 18 to 25% by mass, 18 to 50% by mass, 18 to 40% by mass, 5 to 18% by mass, 12 to 26% by mass, or more than 12% by mass and not more than 26% by mass.

The combination of the proportion of monomer units of the styrene-based compound and the proportion of monomer units of (meth)acrylonitrile is arbitrary, and the proportion of monomer units of the styrene-based compound and the proportion of monomer units of (meth)acrylonitrile may each be within the ranges described above. For example, the aromatic vinyl polymer may be in an embodiment in which the proportion of the monomer units of the styrene-based compound is 50 to 95% by mass and the proportion of the monomer units of the (meth)acrylonitrile is 5 to 50% by mass, based on the entire aromatic vinyl polymer or on the total amount of the monomer units of the styrene-based compound and the monomer units of the (meth)acrylonitrile (the total amount of the monomer units of the styrene-based compound, the monomer units of the acrylonitrile, and the monomer units of the methacrylonitrile), the proportion of the monomer units of the styrene-based compound is 68 to 90% by mass and the proportion of the monomer units of the (meth)acrylonitrile is 10 to 32% by mass, or the proportion of the monomer units of the styrene-based compound is 74 to 88% by mass and the proportion of the monomer units of the (meth)acrylonitrile is 12 to 26% by mass.

In an aromatic vinyl polymer, the total amount of monomer units of a styrene-based compound and monomer units of (meth)acrylonitrile (the total amount of monomer units of a styrene-based compound, monomer units of acrylonitrile, and monomer units of methacrylonitrile) may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 92% by mass or more, 95% by mass or more, 96% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or substantially 100% by mass based on the entire aromatic vinyl polymer, from the viewpoint of easily obtaining excellent volume, combability, and spinnability.

The content of the aromatic vinyl polymer is more than 0% by mass and less than 100% by mass based on the total mass of the artificial hair fiber or the total amount of the vinyl chloride polymer and the aromatic vinyl polymer, and may be in the following range. The content of the aromatic vinyl polymer may be 2% by mass or more, 4% by mass or more, 5% by mass or more, more than 5% by mass, 10% by mass or more, 15% by mass or more, 17% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more, from the viewpoint of easily obtaining an excellent sense of volume. The content of the aromatic vinyl polymer may be 60% by mass or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 17% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, less than 5% by mass, or 4% by mass or less, from the viewpoint of easily obtaining an excellent combability and spinnability. From these viewpoints, the content of the aromatic vinyl polymer may be 2 to 60 mass%, 4 to 50 mass%, 4 to 40 mass%, 4 to 35 mass%, 4 to 30 mass%, 5 to 40 mass%, 10 to 35 mass%, 20 to 35 mass%, or 30 to 35 mass%.

The combination of the vinyl chloride polymer content and the aromatic vinyl polymer content is arbitrary, and the vinyl chloride polymer content and the aromatic vinyl polymer content may be in the ranges described above. For example, the artificial hair fiber according to this embodiment may have a vinyl chloride polymer content of 40 to 98% by mass and an aromatic vinyl polymer content of 2 to 60% by mass, a vinyl chloride polymer content of 60 to 95% by mass and an aromatic vinyl polymer content of 5 to 40% by mass, or a vinyl chloride polymer content of 68 to 90% by mass and an aromatic vinyl polymer content of 10 to 32% by mass, based on the total mass of the artificial hair fiber or the total amount of the vinyl chloride polymer and the aromatic vinyl polymer.

The total amount of vinyl chloride polymer and aromatic vinyl polymer may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 92% by mass or more, 95% by mass or more, 96% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or substantially 100% by mass, based on the total mass of the artificial hair fiber.

The artificial hair fiber according to this embodiment may contain components other than vinyl chloride polymer and aromatic vinyl polymer. Such components include polymers other than vinyl chloride polymer and aromatic vinyl polymer (polyolefins such as polypropylene; polyethylene terephthalate; polymers of (meth)acrylic acid compounds such as (meth)acrylic acid and (meth)acrylic acid esters, etc.), antistatic agents, heat stabilizers, lubricants, processing aids, plasticizers, strengthening agents, ultraviolet absorbers, antioxidants, fillers, flame retardants, pigments, initial coloring improvers, conductivity imparting agents, fragrances, etc. The artificial hair fiber according to this embodiment may not contain at least one of such components, and may not contain at least one selected from the group consisting of polyolefins (polypropylene, etc.), polyethylene terephthalate, and polymers of (meth)acrylic acid compounds ((meth)acrylic acid, (meth)acrylic acid esters, etc.).

Examples of antistatic agents include cationic, anionic, and amphoteric antistatic agents. The content (mixture amount) of the antistatic agent may be 0.01 to 1 part by mass per 100 parts by mass of the vinyl chloride polymer and aromatic vinyl polymer combined, or 100 parts by mass of the artificial hair fiber (fibrous resin composition).

Heat stabilizers can be used to adjust thermal decomposition during molding, long-run properties, filament color tone, etc. Examples of heat stabilizers include Ca-Zn-based heat stabilizers, hydrotalcite-based heat stabilizers, tin-based heat stabilizers, epoxy-based heat stabilizers, and β-diketone-based heat stabilizers. The content (blended amount) of the heat stabilizer may be 0.1 to 5.0 parts by mass per 100 parts by mass of the vinyl chloride polymer and aromatic vinyl polymer combined, or 100 parts by mass of the artificial hair fiber (fibrous resin composition).

Examples of Ca-Zn-based heat stabilizers include zinc stearate, calcium stearate, zinc 12-hydroxystearate, calcium 12-hydroxystearate, etc. Examples of hydrotalcite-based heat stabilizers include hydrotalcite compounds, etc. Examples of hydrotalcite compounds include complex salt compounds consisting of magnesium and/or an alkali metal and aluminum; complex salt compounds consisting of zinc, magnesium, and aluminum; compounds in which water of crystallization has been dehydrated, etc. Examples of the tin-based heat stabilizer include mercaptotin-based heat stabilizers such as dimethyltin mercapto, dimethyltin mercaptide, dibutyltin mercapto, dioctyltin mercapto, dioctyltin mercapto polymer, and dioctyltin mercaptoacetate; maleatetin-based heat stabilizers such as dimethyltin maleate, dibutyltin maleate, dioctyltin maleate, and dioctyltin maleate polymer; and lauratetin-based heat stabilizers such as dimethyltin laurate, dibutyltin laurate, and dioctyltin laurate. Examples of the epoxy-based heat stabilizer include epoxidized soybean oil and epoxidized linseed oil. Examples of the β-diketone-based heat stabilizer include stearoylbenzoylmethane (SBM), dibenzoylmethane (DBM), and the like.

Lubricants can be used to reduce friction with the metal surface of the processing machine and between resins, improve fluidity, and adjust processability. Examples of lubricants include metal soap-based lubricants, higher fatty acid-based lubricants, ester-based lubricants, higher alcohol-based lubricants, and hydrocarbon-based lubricants. The content (blended amount) of the lubricant may be 0.2 to 5.0 parts by mass per 100 parts by mass of the vinyl chloride polymer and aromatic vinyl polymer combined, or 100 parts by mass of the artificial hair fiber (fibrous resin composition).

Metal soap-based lubricants include metal soaps (e.g., stearates, laurates, palmitates, and oleates of Na, Mg, Al, Ca, and Ba). Higher fatty acid-based 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 thereof. Ester-based lubricants include pentaerythritol-based lubricants, montanic acid wax-based lubricants, and lubricants consisting of alcohol and fatty acid. Pentaerythritol-based lubricants include monoesters, diesters, triesters, or tetraesters of pentaerythritol or dipentaerythritol and higher fatty acids; and mixtures thereof. Montanic acid wax-based lubricants include 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, oleyl alcohol, etc. Examples of hydrocarbon lubricants include polyethylene wax, polypropylene wax, etc.

The content of vinyl chloride-based acrylic graft copolymer in the artificial hair fiber of this embodiment may be 1 part by mass or less, less than 1 part by mass, 0.1 parts by mass or less, 0.01 parts by mass or less, or substantially 0 parts by mass per 100 parts by mass of the total of vinyl chloride polymer and vinyl polymer (e.g., aromatic vinyl polymer).

The method for producing fibers for artificial hair according to this embodiment includes a heating step in which a base fiber containing a vinyl chloride polymer and an aromatic vinyl polymer is heat-treated to obtain fibers for artificial hair. The base fiber may be a fiber obtained in a stretching step described below. In the heating step, for example, the base fiber may be heat-treated using a heat treatment machine in an air atmosphere until the total fiber length shrinks to 0.5 to 0.9 times the length before treatment.

The glass transition temperature (Tg) of the base fiber may be in the following range. The glass transition temperature may be 80°C or more, 85°C or more, 90°C or more, 94°C or more, 95°C or more, 100°C or more, 104°C or more, 105°C or more, 108°C or more, 109°C or more, 110°C or more, 115°C or more, 116°C or more, 120°C or more, or 124°C or more, from the viewpoint of easily obtaining excellent combability. The glass transition temperature may be 150°C or less, 140°C or less, 130°C or less, 125°C or less, 124°C or less, 120°C or less, 116°C or less, 115°C or less, 110°C or less, 109°C or less, 108°C or less, 105°C or less, 104°C or less, or 100°C or less, from the viewpoint of easily obtaining excellent volume. The glass transition temperature may be 95°C or less, or 94°C or less. From these viewpoints, the glass transition temperature may be 80 to 150° C., 94 to 124° C., or 100 to 115° C. The glass transition temperature can be measured by the method described in the Examples below.

The heating temperature in the heating process may be less than 120°C, 115°C or less, 110°C or less, or 105°C or less. The heating temperature in the heating process may be 80°C or more, 90°C or more, 100°C or more, 105°C or more, or 110°C or more. From these perspectives, the heating temperature in the heating process may be 80°C or more and less than 120°C, 90 to 115°C, or 100 to 110°C.

In the method for producing artificial hair fibers according to this embodiment, artificial hair fibers having a large heat shrinkage at 100°C are easily obtained at a heating temperature of less than 120°C (e.g., 110°C or less). For example, when the glass transition temperature of the base fiber is low (e.g., the glass transition temperature is less than 120°C) and the temperature difference between the glass transition temperature and the temperature of the heat shrinkage rate of 100°C is small, if the heating temperature is less than 120°C, artificial hair fibers having a large heat shrinkage rate are easily obtained. Also, when the glass transition temperature of the base fiber is high (e.g., the glass transition temperature is 120°C or more), even if the temperature difference between the glass transition temperature and the temperature of the heat shrinkage rate of 100°C is large, artificial hair fibers having a large heat shrinkage rate are easily obtained when the heating temperature is less than 120°C.

The method for producing artificial hair fibers according to this embodiment may include a melt-kneading step in which a vinyl chloride polymer and an aromatic vinyl polymer are melt-kneaded. In the melt-kneading step, for example, a vinyl chloride polymer and an aromatic vinyl polymer are stirred and mixed to obtain a powder compound, and then the powder compound is melt-kneaded to obtain a pellet compound. When stirring and mixing the vinyl chloride polymer and the aromatic vinyl polymer, an antistatic agent, a heat stabilizer, a lubricant, etc. may be mixed as appropriate. In the stirring and mixing to obtain the powder compound, a Henschel mixer, a super mixer, a ribbon blender, etc. can be used. In the melt-kneading to obtain the pellet compound, a single screw extruder, a counter-rotating twin screw extruder, a conical twin screw extruder, a same-rotating twin screw extruder, a co-kneader, a planetary gear extruder, a roll kneader, etc. can be used.

The method for producing artificial hair fibers according to this embodiment may include a melt spinning step in which a resin composition (pellet compound obtained in the melt kneading step) containing a vinyl chloride polymer and an aromatic vinyl polymer is melt spun after the melt kneading step. In the melt spinning step, for example, a metal nozzle having multiple nozzle holes is used to extrude the resin composition under conditions of a cylinder temperature of 140 to 190°C and a nozzle temperature of 180±15°C to perform melt spinning. For extrusion, a single screw extruder, a counter-rotating twin screw extruder, a conical twin screw extruder, or the like may be used, and a single screw extruder with a diameter of 30 to 85 mmφ or a conical extruder with a diameter of 30 to 50 mmφ may be used.

The method for producing fibers for artificial hair according to this embodiment may include a winding process for winding the fibers obtained in the melt spinning process after the melt spinning process. In the winding process, the fibers obtained in the melt spinning process may be introduced into a heating cylinder (heating cylinder temperature: about 250°C), instantaneously heat-treated, and then wound up by a take-up machine. During winding, the take-up speed may be adjusted so that the fiber has a single fiber fineness of 150 to 206 decitex.

The method for producing fibers for artificial hair according to this embodiment may include a drawing process after the winding process, in which the fibers (undrawn fibers) are drawn to obtain base fibers (base fibers to be heat-treated in the heating process). In the drawing process, for example, the undrawn fibers may be drawn 2 to 4 times in a drawing machine (in an air atmosphere, 90 to 120°C).

The fiber bundle for artificial hair according to this embodiment comprises the fiber for artificial hair according to this embodiment. The fiber bundle for artificial hair according to this embodiment may comprise a plurality of the fibers for artificial hair according to this embodiment. One aspect of the fiber bundle for artificial hair according to this embodiment may be a fiber bundle made of the fiber for artificial hair according to this embodiment. Another aspect of the fiber bundle for artificial hair according to this embodiment may further comprise, in addition to the fiber for artificial hair according to this embodiment, a fiber different from the fiber for artificial hair (fiber for artificial hair; fiber not corresponding to the fiber for artificial hair according to this embodiment), that is, the fiber for artificial hair according to this embodiment and a fiber different from the fiber for artificial hair.

By using the artificial hair fiber according to this embodiment in combination with a fiber different from the artificial hair fiber, it is possible to obtain other desired properties while obtaining an excellent sense of volume. The constituent material of the fiber different from the artificial hair fiber according to this embodiment may be a fiber that does not contain vinyl chloride polymer and aromatic vinyl polymer, a fiber that contains one of vinyl chloride polymer and aromatic vinyl polymer, or a fiber whose heat shrinkage rate at 100°C is less than 7%. The constituent material of the fiber different from the artificial hair fiber according to this embodiment may be a polyolefin such as polypropylene; polyethylene terephthalate; a polymer of a (meth)acrylic acid compound such as (meth)acrylic acid or a (meth)acrylic acid ester.

The artificial hair fiber and the artificial hair fiber bundle according to this embodiment can be used in the hair accessory product according to this embodiment. The hair accessory product according to this embodiment includes the artificial hair fiber according to this embodiment, and may include the artificial hair fiber bundle according to this embodiment. Examples of hair accessory products include wigs. The artificial hair fiber and the artificial hair fiber bundle in the hair accessory product according to this embodiment may be in either a state before or after a gear processing treatment to frizz the artificial hair fiber. The artificial hair according to this embodiment can be obtained by performing a gear processing treatment on the artificial hair fiber according to this embodiment.

Below, specific embodiments of the present invention are explained in more detail using examples and comparative examples, but the present invention is not limited to these examples.

<Preparation of artificial hair fibers>
Example 1
A resin composition consisting of 70 parts by mass of vinyl chloride polymer (vinyl chloride resin, vinyl chloride homopolymer, Taiyo PVC Co., Ltd., product name: TH-1000), 30 parts by mass of aromatic vinyl polymer containing 68% by mass of styrene monomer unit and 32% by mass of acrylonitrile monomer unit (aromatic vinyl copolymer resin, Denka Co., Ltd., product name: GR-AT-6S), 0.5 parts by mass of antistatic agent (NOF Corporation, product name: New Elegan ASK), 3 parts by mass of hydrotalcite complex salt compound (Nissan Chemical Industries, Ltd., product name: CP-410A), 0.5 parts by mass of epoxidized soybean oil (Asahi Denka Kogyo Co., Ltd., product name: O-130P), and 0.8 parts by mass of ester lubricant (Riken Vitamin Co., Ltd., product name: EW-100) was prepared. Using the resin composition, pellets were produced by compounding with an extruder having a diameter (caliber) of 40 mm at a cylinder temperature of 130 to 170 ° C. Next, the above pellets were melt spun in an extruder having a diameter of 30 mm at an extrusion rate of 10 kg/hour using a nozzle with a nozzle cross-sectional area of 0.06 mm ² , a round shape, and 120 holes, at a cylinder temperature of 140 to 190° C. and a nozzle temperature of 180° C. After that, the pellets were heat-treated for 1.0 second in a heating cylinder (250° C.) located 4.5 m directly below the nozzle to obtain fiber A (undrawn fiber) of 150 dtex.

The glass transition temperature (Tg) of the above-mentioned fiber A was measured as the peak top temperature of the loss tangent (tan δ) in dynamic viscoelasticity measurement. Specifically, using a dynamic viscoelasticity measuring device (SII NanoTechnology, Inc., DMS6100), the loss tangent (tan δ) of a fiber bundle of 40 fibers A in the range of 25 to 170°C was measured at a heating rate of 4°C/min, a frequency of 1 Hz, and a chuck distance of 3 mm, and the peak top temperature was measured. The glass transition temperature of fiber A in Example 1 was 124°C.

Next, fiber A was stretched three times in an air atmosphere at 100°C to obtain fiber B.

Next, fiber B was heat-treated in an air atmosphere at a heating temperature (annealing temperature) of 110°C until the total length of the fiber shrunk to 0.75 times its length before treatment, thereby obtaining a 60 decitex artificial hair fiber.

(Examples 2 to 11 and Comparative Examples 1 to 3)
A 60 dtex artificial hair fiber was obtained in the same manner as in Example 1, except that the vinyl chloride polymer content, the aromatic vinyl polymer content, the ratio of monomer units in the aromatic vinyl polymer, and the heating temperature (annealing temperature) of the heat treatment after the stretching treatment were changed to the values in Tables 1 and 2. The aromatic vinyl polymer shown below was used as the aromatic vinyl polymer different from that in Example 1. The measurement results of the glass transition temperature of Fiber A are shown in Tables 1 and 2.

Aromatic vinyl polymer containing 70% by mass of styrene monomer units and 30% by mass of acrylonitrile monomer units (manufactured by Denka Co., Ltd., product name: GR-AT-R)
An aromatic vinyl polymer containing 75% by mass of styrene monomer units and 25% by mass of acrylonitrile monomer units (manufactured by Denka Co., Ltd., product name: AS700)
Aromatic vinyl polymer containing 80% by mass of styrene monomer units and 20% by mass of acrylonitrile monomer units (manufactured by Denka Co., Ltd., product name: AS-3)
An aromatic vinyl polymer containing 82% by mass of styrene monomer units and 18% by mass of acrylonitrile monomer units (manufactured by Denka Co., Ltd., product name: AS-C800)
Aromatic vinyl polymer containing 86% by mass of styrene monomer units and 14% by mass of acrylonitrile monomer units (self-prepared product)
Aromatic vinyl polymer containing 90% by mass of styrene monomer units and 10% by mass of acrylonitrile monomer units (self-prepared product)

<Heat shrinkage rate of artificial hair fibers>
First, the above-mentioned artificial hair fiber was cut to a length of 100 mm to obtain a fiber piece. Next, the fiber piece was heated for 10 minutes in an oven set at 100° C., and then the length of the fiber piece was measured. The thermal shrinkage rate was calculated according to the following formula. The results are shown in Tables 1 and 2.
Heat shrinkage rate (%) = {[(length before heating) - (length after heating)] / (length before heating)} x 100

<Evaluation>
The above-mentioned artificial hair fibers were evaluated for spinnability, volume, and combability (comb resistance) according to the following evaluation methods and criteria. The results are shown in Tables 1 and 2. It is confirmed that good results were obtained in all evaluation items in the examples.

(Spinnability)
As the spinnability, the occurrence of yarn breakage per hour during the melt spinning process to produce fiber A (undrawn fiber) in the above-mentioned production of artificial hair fiber was visually observed. The spinnability was evaluated according to the following criteria.
A: 1 thread break B: 2-3 thread breaks C: 4 or more thread breaks

(Volume)
The volume was evaluated by the following procedure. First, the fiber bundle (number: 12,000, length: 10 m, mass: 800 g) of the above-mentioned artificial hair fiber was subjected to gear processing (processing in the length direction of the fiber, depth of the gear wave groove: 2.5 mm, gear pitch: 2.5 mm, surface temperature: 90° C., processing speed: 1.0 m/min) to obtain a fiber for evaluation, and then the fiber for evaluation was cut to a length of 100 mm to obtain a fiber piece. Next, the fiber pieces were filled into a 56 cc container (100 mm×14 mm×40 mm) until the container was full. After removing the filled fiber pieces, the mass of the fiber pieces was measured. Then, the specific volume was calculated from the formula "Volume of container (cc)/Mass of fiber pieces (g)=specific volume (cc/g)". The value of the specific volume was calculated by rounding off to one decimal place. A specific volume exceeding 7.0 cc/g was judged to be good.

(Combability)
The combability was evaluated by the following procedure. First, a fiber bundle of the above-mentioned artificial hair fiber (number: 12,000, length: 10 m, mass: 800 g) was subjected to gear processing (processing in the length direction of the fiber, depth of the gear wave groove: 2.5 mm, gear pitch: 2.5 mm, surface temperature: 90° C., processing speed: 1.0 m/min) to obtain a fiber bundle for evaluation. After adjusting the fiber bundle to a length of 30 cm and a mass of 20 g, the resistance force [unit: gf] when combed at a moving speed of 10 mm/sec and a moving distance of 100 mm was measured with a static and dynamic friction measuring device (manufactured by TRIINITY-LAB, product name "TL201Tt"). It was determined that the smaller the resistance force, the better the combability.

Claims (8)

Contains a vinyl chloride polymer and an aromatic vinyl polymer,
the content of the vinyl chloride polymer is more than 0 mass% and 75 mass% or less based on the total amount of the vinyl chloride polymer and the aromatic vinyl polymer,
The aromatic vinyl polymer has a styrene-based compound and (meth)acrylonitrile as monomer units,
the total amount of the monomer units of the styrene-based compound and the monomer units of the (meth)acrylonitrile is 90 mass% or more based on the total amount of the aromatic vinyl polymer,
A fiber for artificial hair, having a heat shrinkage rate of 7% or more at 100°C. The artificial hair fiber according to claim 1, wherein the heat shrinkage rate is 7 to 25%. 2. The fiber for artificial hair according to claim 1, wherein the content of said vinyl chloride polymer is 60 to 75 % by mass, and the content of said aromatic vinyl polymer is 25 to 40% by mass, based on the total amount of said vinyl chloride polymer and said aromatic vinyl polymer. 2. The artificial hair fiber according to claim 1 , wherein the styrene-based compound comprises styrene. 2. The fiber for artificial hair according to claim 1, wherein the proportion of the monomer units of the styrene-based compound is 74 to 88% by mass, and the proportion of the monomer units of the (meth)acrylonitrile is 12 to 26% by mass, based on the entirety of the aromatic vinyl polymer. A fiber bundle for artificial hair, comprising the fiber for artificial hair according to any one of claims 1 to 5 . The fiber bundle for artificial hair according to claim 6 , further comprising fibers different from the fibers for artificial hair. A hair accessory product comprising the artificial hair fiber bundle according to claim 6 .