Modacrylic fibers, head ornament product containing same, and method for producing same

Abstract

One or more embodiments of the present invention relate to modacrylic fibers comprising a modacrylic resin, wherein: the modacrylic resin is a graft copolymer including 35-84 mass% of a constituent unit derived from acrylonitrile, 15-64 mass% of a constituent unit derived from a vinyl halide and / or a vinylidene halide, 0.5-9.5 mass% of a constituent unit derived from a carboxylic acid ester-based monomer, and 0.5-40 mass% of a constituent unit derived from a macromonomer having, in the main chain, a polymer including an ethylenically unsaturated monomer; and the carboxylic acid ester-based monomer is at least one selected from the group consisting of a vinyl ester and a hydroxyalkyl (meth)acrylate.

Description

Modacrylic fiber, headwear products containing the same, and manufacturing method thereof

[0001] The present invention relates to modacrylic fibers that can be used as artificial hair as a substitute for human hair, head accessories containing the same, and a method for producing the same.

[0002] Modacrylic fibers containing less than 85% by mass of acrylonitrile are used as artificial hair because they resemble human hair in terms of texture, luster, volume, etc. For example, modacrylic fibers are typically produced by wet-spinning a modacrylic resin obtained by copolymerizing acrylonitrile with vinyl halide and / or vinylidene halide (see, for example, Patent Document 1). However, wet-spinning methods involve high wastewater loads and high solvent recovery costs, and therefore Patent Documents 2 and 3 discuss melt-spinning modacrylic fibers.

[0003] International Publication No. WO 2016 / 158773 International Publication No. WO 2016 / 158774 International Publication No. WO 2019 / 187404

[0004] When modacrylic fibers are used as artificial hair, curls are set using hot water, but curl setting is usually performed at 70 to 90°C, and because there is a risk of burns, it is desirable to lower the temperature of the hot water. Patent Document 1 aims to improve curl setting properties with hot water by adding an organic solvent, but there is a limit to the amount of organic solvent that can be applied, and curl setting with hot water at 70°C or higher is still required. Patent Documents 2 and 3 do not discuss curl setting properties with hot water.

[0005] In order to solve the above-mentioned problems of the conventional art, the present invention provides a modacrylic fiber that has improved curl setting properties when using low-temperature hot water while also having good curl retention, a head accessory product containing the same, and a method for producing the same.

[0006] One or more embodiments of the present invention relate to a modacrylic fiber comprising a modacrylic resin, wherein the modacrylic resin is a graft copolymer containing 35 to 84 mass% of structural units derived from acrylonitrile, 15 to 64 mass% of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5 mass% of structural units derived from carboxylic acid ester monomers, and 0.5 to 40 mass% of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, and the carboxylic acid ester monomer is one or more selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters.

[0007] One or more embodiments of the present invention relate to headwear products comprising the modacrylic fibers.

[0008] One or more embodiments of the present invention relate to a method for producing a modacrylic fiber, the method including the steps of melt-spinning a resin composition containing a modacrylic resin to obtain an undrawn yarn, and drawing the undrawn yarn, wherein the modacrylic resin is a graft copolymer containing 35 to 84 mass% of structural units derived from acrylonitrile, 15 to 64 mass% of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5 mass% of structural units derived from a carboxylic acid ester monomer, and 0.5 to 40 mass% of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, and the carboxylic acid ester monomer is one or more selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters.

[0009] According to one or more embodiments of the present invention, it is possible to provide a modacrylic fiber that exhibits good curl retention while improving curl settability when using low-temperature hot water, and a head accessory product containing the same. Furthermore, according to one or more embodiments of the manufacturing method of the present invention, it is possible to obtain a modacrylic fiber that exhibits good curl retention while improving curl settability when using low-temperature hot water.

[0010] The present inventors have discovered that, in a modacrylic fiber containing a modacrylic resin, a modacrylic resin is used in which a graft copolymer of a macromonomer having in its main chain a polymer of one or more halogen-containing monomers selected from the group consisting of acrylonitrile, vinyl halide, and vinylidene halide, and an ethylenically unsaturated monomer, is further copolymerized with one or more carboxylic acid ester monomers selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters. This allows for a balance between lowering the apparent glass transition temperature (also referred to as the peak temperature of Tan δ) of the modacrylic fiber and increasing the temperature rise by 1 / 10 of the peak temperature of Tan δ without using a large amount of plasticizer. Therefore, a modacrylic fiber can be obtained that has improved curl settability in hot water at low temperatures, e.g., 45 to 65°C, while also exhibiting good curl retention at room temperature (e.g., 5 to 40°C). Lowering the apparent glass transition temperature of the modacrylic fiber makes it easier to set the curl, but it can also make the set curl more easily released. In the present application, by using a graft copolymer having a specific monomer composition as the modacrylic resin as described above, it is possible to obtain a modacrylic fiber that has improved curl settability in hot water at 45 to 65° C., while also exhibiting good curl retention at room temperature, particularly when kept for 7 days at room temperature of 5 to 40° C. Furthermore, the modacrylic fiber of one or more embodiments of the present invention can lower the apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber without using a large amount of plasticizer, thereby suppressing the stickiness that occurs when a large amount of plasticizer is used, and providing a good feel to the touch.

[0011] In this specification, when a numerical range is indicated with "to", the numerical range includes both end values ​​(upper and lower limits). For example, a numerical range of "X to Y" is a range that includes both end values ​​X and Y. Furthermore, when multiple numerical ranges are described in this specification, it is understood that this includes numerical ranges that combine the upper and lower limits of different numerical ranges as appropriate. Furthermore, when multiple upper and lower limits of a numerical range are described separately in this specification, it is understood that this includes numerical ranges that combine the upper and lower limits as appropriate.

[0012] (Modacrylic Fiber) The modacrylic fiber may be any fiber obtained by fiberizing a modacrylic resin. The content of the modacrylic resin in the modacrylic fiber is not particularly limited, but may, for example, contain 60% by mass or more, 80% by mass or more, or 90% by mass or more of the modacrylic resin; or 98% by mass or less, 95% by mass or less, or 90% by mass or less; more specifically, 60 to 98% by mass, or 80 to 95% by mass of the modacrylic resin.

[0013] The modacrylic resin is a graft copolymer containing 35 to 84% by mass of structural units derived from acrylonitrile, 15 to 64% by mass of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5% by mass of structural units derived from carboxylic acid ester monomers, and 0.5 to 40% by mass of structural units derived from a macromonomer (hereinafter also referred to simply as "macromonomer") having a polymer of ethylenically unsaturated monomers in its main chain. In this graft copolymer, the copolymer of acrylonitrile, halogen-containing monomers, and carboxylic acid ester monomers forms the backbone polymer, and the polymer of ethylenically unsaturated monomers forms the branch polymer. The graft copolymer typically has a degree of branching (gM = (square of the average radius of gyration of the branched polymers / square of the average radius of gyration of the linear polymer)) of 0.20 to 0.95, as measured and calculated using a gel permeation chromatography multi-angle light scattering (GPC-MALS) spectrophotometer.

[0014] The graft copolymer exhibits good heat resistance and flame retardancy when it contains the structural units derived from acrylonitrile and the structural units derived from the halogen-containing monomer in the above-mentioned ranges. The graft copolymer can improve its melt processability by containing 0.5% by mass or more of the structural units derived from the macromonomer. Furthermore, the graft copolymer can enhance its polymerization stability by containing 40% by mass or less of the structural units derived from the macromonomer. The graft copolymer can easily lower the apparent glass transition temperature of a modacrylic fiber containing the graft copolymer (modacrylic resin) while increasing the temperature at which the apparent glass transition temperature rises by 1 / 10. This also facilitates improving curl retention while reducing the hot water temperature during hot water curl setting. The graft copolymer contains 9.5% by mass or less of structural units derived from carboxylic acid ester monomers, which prevents a significant decrease in the apparent glass transition temperature of modacrylic fibers containing the graft copolymer (modacrylic resin), thereby maintaining good curl retention and heat resistance. From the viewpoints of melt processability and polymerization stability, the graft copolymer preferably contains 1.0 to 30% by mass, and even more preferably 2.5 to 10% by mass, of structural units derived from the macromonomers. From the viewpoints of appropriately lowering the apparent glass transition temperature of modacrylic fibers containing the graft copolymer (modacrylic resin) while easily maintaining heat resistance, the graft copolymer preferably contains 1.0 to 9.0% by mass, more preferably 1.5 to 8.5% by mass, even more preferably 2.0 to 8.0% by mass, and even more preferably 2.5 to 7.5% by mass of structural units derived from carboxylic acid ester monomers.

[0015] The graft copolymer preferably contains 35 to 74% by mass of structural units derived from acrylonitrile, 24 to 63% by mass of structural units derived from the halogen-containing monomer, 1.0 to 9.0% by mass of structural units derived from a carboxylic acid ester monomer, and 1.0 to 30% by mass of structural units derived from the macromonomer, and more preferably contains 35 to 65% by mass of structural units derived from acrylonitrile, 31 to 61% by mass of structural units derived from the halogen-containing monomer, 1.5 to 8.5% by mass of structural units derived from a carboxylic acid ester monomer, and 2.5 to 10% by mass of structural units derived from the macromonomer. It is more preferable that the copolymer contains 35 to 64.5% by mass of structural units derived from acrylonitrile, 31 to 60.5% by mass of structural units derived from the halogen-containing monomer, 2.0 to 8.0% by mass of structural units derived from carboxylic acid ester monomers, and 2.5 to 10% by mass of structural units derived from the macromonomer, and it is even more preferable that the copolymer contains 35 to 60% by mass of structural units derived from acrylonitrile, 35 to 60% by mass of structural units derived from the halogen-containing monomers, 2.5 to 7.5% by mass of structural units derived from carboxylic acid ester monomers, and 2.5 to 10% by mass of structural units derived from the macromonomer.

[0016] The vinyl halide is not particularly limited, and examples thereof include vinyl chloride, vinyl bromide, and vinyl iodide. The vinylidene halide is not particularly limited, and examples thereof include vinylidene chloride, vinylidene bromide, and vinylidene iodide. These may be used alone or in combination of two or more. From the viewpoint of heat resistance, it is preferable to use vinyl chloride and / or vinylidene chloride.

[0017] The carboxylic acid ester monomer includes at least one selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters. In this specification, (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0018] The vinyl ester may be a fatty acid vinyl ester or an aromatic carboxylic acid vinyl ester.

[0019] In the fatty acid vinyl ester, the number of carbon atoms of the fatty acid is not particularly limited and may be, for example, 1 to 20 or 2 to 15. Specific examples of fatty acid vinyl esters include saturated fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl palmitate, and vinyl stearate. From the viewpoints of reactivity with other monomers and achieving both a decrease in the apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber and an increase in the temperature rise by 1 / 10 of the peak temperature of Tan δ, the number of carbon atoms of the fatty acid is preferably 2 to 5.

[0020] In the aromatic carboxylic acid vinyl ester, the number of carbon atoms of the aromatic carboxylic acid is not particularly limited, but may be, for example, 7 to 9. Specific examples of the aromatic carboxylic acid vinyl ester include vinyl benzoate and vinyl cinnamate.

[0021] In the hydroxyalkyl (meth)acrylate ester, the number of carbon atoms in the hydroxyalkyl group is not particularly limited, and is, for example, preferably 1 to 10, and more preferably 1 to 4. Specific examples of the hydroxyalkyl (meth)acrylate ester include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0022] The carboxylic acid ester monomer may be used alone or in combination of two or more. The carboxylic acid ester monomer preferably contains a vinyl ester from the viewpoint of preventing the modacrylic fiber from becoming hard during curl setting with hot water. Furthermore, from the viewpoint of easily achieving both a decrease in the apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber and an increase in the 1 / 10 increase temperature of the peak temperature of Tan δ, the vinyl ester preferably contains one or more selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate, and more preferably contains one or more selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl pivalate.

[0023] Generally, a macromonomer refers to an oligomer molecule having a reactive functional group at the end of the polymer. In one or more embodiments of the present invention, a macromonomer having a polymer of an ethylenically unsaturated monomer in its main chain is used.

[0024] Various ethylenically unsaturated monomers can be used as the main chain polymer of the macromonomer. Examples include (meth)acrylic acid, (meth)acrylic acid ester monomers, styrene monomers, nitrile group-containing vinyl monomers, amide group-containing vinyl monomers, fluorine-containing vinyl monomers, silicon-containing vinyl monomers, maleimide monomers, vinyl esters, alkenes, and conjugated dienes. In addition, maleic anhydride, maleic acid, monoalkyl esters and dialkyl esters of maleic acid; fumaric acid, monoalkyl esters and dialkyl esters of fumaric acid; allyl chloride; and allyl alcohol can also be used.

[0025] Examples of the (meth)acrylic acid ester monomer include aliphatic hydrocarbon (e.g., alkyl having 1 to 18 carbon atoms) (meth)acrylic acid esters, alicyclic hydrocarbon (meth)acrylic acid esters, aromatic hydrocarbon (meth)acrylic acid esters, aralkyl (meth)acrylic acid esters, etc. More specific examples include methyl (meth)acrylate, n-butyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, and benzyl (meth)acrylate.

[0026] As the (meth)acrylic acid ester-based monomer, for example, a (meth)acrylic acid ester-based monomer having a heteroatom in the ester moiety may be used. The heteroatom is not particularly limited, and examples thereof include oxygen (O), fluorine (F), and nitrogen (N). Specific examples of the (meth)acrylic acid ester-based monomer having a heteroatom in the ester moiety include 2-methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, and 2,2,2-trifluoroethyl (meth)acrylate.

[0027] Examples of the styrene-based monomers include styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and its salts. Examples of the nitrile group-containing vinyl-based monomers include (meth)acrylonitrile. Examples of the amide group-containing vinyl-based monomers include (meth)acrylamide. Examples of the fluorine-containing vinyl monomers include perfluoroethylene, perfluoropyrene, and vinylidene fluoride. Examples of the silicon-containing vinyl monomers include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of the maleimide-based monomers include maleimide, methylmaleimide, and phenylmaleimide. Examples of the vinyl esters include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate. Examples of the alkenes include ethylene and propylene. Examples of the conjugated dienes include butadiene and isoprene.

[0028] From the viewpoint of melt processability and physical properties, such as spinnability, of the modacrylic resin, the ethylenically unsaturated monomer preferably includes one or more selected from the group consisting of (meth)acrylic acid ester monomers, styrene monomers, nitrile group-containing vinyl monomers, amide group-containing vinyl monomers, silicon-containing vinyl monomers, maleimide monomers, vinyl esters, alkenes, conjugated dienes, maleic anhydride, maleic acid, monoalkyl esters of maleic acid, dialkyl esters of maleic acid, fumaric acid, monoalkyl esters of fumaric acid, dialkyl esters of fumaric acid, allyl chloride, and allyl alcohol; more preferably one or more selected from the group consisting of (meth)acrylic acid ester monomers, styrene monomers, nitrile group-containing vinyl monomers, and amide group-containing vinyl monomers; even more preferably one or more selected from the group consisting of (meth)acrylic acid ester monomers and nitrile group-containing vinyl monomers; and even more preferably a (meth)acrylic acid ester monomer.

[0029] The above-mentioned ethylenically unsaturated monomers may be used alone or in the form of copolymers of two or more kinds.

[0030] The macromonomer has at least one reactive functional group per molecule at a molecular terminal. For example, the macromonomer may have reactive functional groups at both molecular terminals, but from the viewpoint of enhancing the fluidity of the modacrylic resin, it is preferable that the macromonomer have a reactive functional group at one molecular terminal. Examples of the reactive functional group include functional groups selected from the group consisting of allyl groups, vinylsilyl groups, vinyl ether groups, dicyclopentadienyl groups, and groups having a polymerizable carbon-carbon double bond represented by the following general formula (1). From the viewpoint of excellent reactivity with other monomers such as halogen-containing monomers, the reactive functional group is preferably a functional group having a polymerizable carbon-carbon double bond represented by the following general formula (1):

[0031]

[0032] In the general formula (1), R 1 and R 2 may be the same or different and each independently represents hydrogen or an organic group having 1 to 20 carbon atoms. The organic group may be an alkyl group having 1 to 20 carbon atoms, and the alkyl group may be substituted. R 1 and R 2 Specific examples of the group are not particularly limited, and include, for example, —H, —CH3, —(CH2) n A group selected from the group consisting of CH3 (n is an integer of 1 to 19), -C6H5, -CH2OH, and -CN is preferred, and a group selected from the group consisting of -H and -CH3 is more preferred.

[0033] The method for producing the macromonomer is not particularly limited, and a conventionally known method, such as a radical polymerization method, can be used. Examples include known methods such as a general radical polymerization method or a controlled radical polymerization method as described in JP-A-2006-299240, etc., and any of these production methods may be used. However, a controlled radical polymerization method is usually used, and living radical polymerization method and atom transfer radical polymerization method are particularly preferred from the viewpoint of ease of control, etc.

[0034] The macromonomers may be used alone or in combination of two or more.

[0035] The number average molecular weight of the macromonomer is not particularly limited, but from the viewpoint of further improving the melt spinnability of the modacrylic resin, it is preferably 2,000 to 25,000, and more preferably 3,000 to 20,000. The molecular weight distribution (mass average molecular weight / number average molecular weight) of the macromonomer is not particularly limited, but from the viewpoint of ensuring uniformity in the melting behavior of the graft copolymer, it is preferably 1.1 to 1.8, and more preferably 1.1 to 1.5.

[0036] The method for producing the modacrylic resin is not particularly limited, but copolymerization in an aqueous medium is preferred, for example, from the viewpoints of ease of polymerization control and ease of separation and washing of polymer particles after polymerization. Examples of polymerization methods in an aqueous medium include suspension polymerization, microsuspension polymerization, and emulsion polymerization. Among these, suspension polymerization or microsuspension polymerization is preferred, and suspension polymerization is more preferred, from the viewpoint of polymerization stability.

[0037] In the suspension polymerization method or the microsuspension polymerization method, the above-mentioned monomers, dispersants, polymerization initiators, chain transfer agents, etc. are charged all at once, in portions, or continuously as needed, and the copolymerization reaction can be carried out at a predetermined polymerization temperature, for example, 25 to 100°C.

[0038] As the dispersant, any dispersant that is used for polymerization in an aqueous medium can be used appropriately, and examples thereof include partially saponified polyvinyl acetate, water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and carboxymethyl cellulose, polyethylene oxide, polyvinylpyrrolidone, etc. These may be used alone or in combination of two or more.

[0039] The polymerization initiator is not particularly limited, and for example, an oil-soluble polymerization initiator can be used. Examples of such oil-soluble polymerization initiators include organic peroxide-based polymerization initiators such as diisobutyl peroxide, diisopropyl peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, and 1,1,3,3-tetramethylbutyl peroxyneodecanoate; and azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). These oil-soluble polymerization initiators may be used alone or in combination of two or more. These oil-soluble polymerization initiators can be added without any particular restrictions, but when used by dissolving them in an organic solvent, examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and isoparaffin, ketones such as acetone, and esters such as ethyl acetate and butyl acetate. These organic solvents may be used alone or in combination of two or more.

[0040] The chain transfer agent is not particularly limited, and any agent used for polymerization in an aqueous medium can be used as appropriate, and suitable examples thereof include alkyl mercaptans having a main chain carbon number of 2 to 12, mercapto alcohols, etc. More specific examples include n-octyl mercaptan, t-dodecyl mercaptan, and 2-mercaptoethanol.

[0041] In the suspension polymerization method or the microsuspension polymerization method, surfactants, dispersing aids, antioxidants, polymerization degree regulators, particle size regulators, pH regulators, gelling property improvers, antistatic agents, stabilizers, scale inhibitors, and the like can be appropriately used as needed within the scope of the object of the present invention.

[0042] According to suspension polymerization or microsuspension polymerization, the modacrylic resin is obtained in the form of a latex or a slurry. There are no particular limitations on the method for drying this to obtain a powdery or granular copolymer resin, and examples thereof include a method in which the latex or slurry is dehydrated and then dried by static drying using a hot air dryer or the like.

[0043] The modacrylic resin is not particularly limited, but from the viewpoint of melt flowability, the weight average molecular weight is preferably 10,000 to 300,000, more preferably 20,000 to 150,000, and even more preferably 30,000 to 120,000.

[0044] The modacrylic resin is not particularly limited, but from the viewpoint of ensuring uniformity in melting behavior, the molecular weight distribution (mass average molecular weight / number average molecular weight) is preferably 1.1 to 7.0, and more preferably 1.1 to 5.0.

[0045] The modacrylic resin is not particularly limited, but when dimethylformamide is used as a solvent, the specific viscosity at 30° C. is preferably 0.05 to 0.30, and more preferably 0.05 to 0.20. In this specification, the specific viscosity can be measured specifically as described in the examples.

[0046] The modacrylic fiber is not particularly limited, but from the viewpoints of touch and spinnability, it is preferable that the modacrylic fiber contains 0.3 to 7 parts by mass of a plasticizer per 100 parts by mass of modacrylic resin. From the viewpoints of suppressing stickiness and improving touch, it is more preferable that the modacrylic fiber contains 5.5 parts by mass or less per 100 parts by mass of modacrylic resin.

[0047] The plasticizer is not particularly limited, and any plasticizer that can be used for modacrylic resins can be used appropriately. Examples of the plasticizer include sulfone compounds such as dimethyl sulfone, diethyl sulfone, dipropyl sulfone, and dibutyl sulfone; sulfoxide compounds such as dipropyl sulfoxide, diisopropyl sulfoxide, methylphenyl sulfoxide, dibutyl sulfoxide, and benzyl sulfoxide; lactides such as lactide lactic acid; lactams such as pyrrolidone, N-vinyl pyrrolidone, and ε-caprolactam; and lactones such as γ-butyrolactone and ε-caprolactone. The plasticizers may be used alone or in combination of two or more.

[0048] From the viewpoint of improving the feel of the modacrylic fiber after curl setting with hot water, the plasticizer preferably has a melting point of 60° C. or higher, more preferably 90° C. or higher. For example, it is preferable to use one or more selected from the group consisting of dimethyl sulfone, lactide lactic acid, and ε-caprolactam, and it is more preferable to use one or more selected from the group consisting of dimethyl sulfone and lactide lactic acid.

[0049] The modacrylic fiber may further contain a stabilizer to further enhance thermal stability. Examples of the stabilizer include at least one stabilizer selected from the group consisting of epoxy-based heat stabilizers, hydrotalcite-based heat stabilizers, tin-based heat stabilizers, Ca—Zn-based heat stabilizers, and β-diketone-based heat stabilizers. One type of stabilizer may be used alone, or two or more types may be used in combination. The amount of stabilizer added is preferably 0.1 to 30 parts by mass, more preferably 0.2 to 20 parts by mass, per 100 parts by mass of the modacrylic resin.

[0050] The modacrylic fiber may contain a lubricant to reduce heat generation due to friction and shear between the modacrylic resin and the processing machine, and to improve fluidity and releasability, as long as the object of the present invention is not impaired. Examples of lubricants that can be used include fatty acid ester-based lubricants, hydrocarbon-based lubricants, fatty acid-based lubricants, higher alcohol-based lubricants, aliphatic amide-based lubricants, alkylene fatty acid amide-based lubricants, and metal soap-based lubricants. These may be used alone or in combination of two or more. The amount of the lubricant added may be 10 parts by mass or less, 5 parts by mass or less, or 0.01 to 3 parts by mass per 100 parts by mass of the modacrylic resin.

[0051] The modacrylic fiber may contain a processing aid such as a modacrylic processing aid, provided that the objectives of the present invention are not impaired. For example, from the viewpoint of improving spinnability, it is preferable to use a (meth)acrylate polymer and / or a styrene-acrylonitrile copolymer as the processing aid. As the (meth)acrylate polymer, a copolymer of (meth)acrylate with a copolymerization component such as butyl (meth)acrylate, styrene, and acrylonitrile can be used. Furthermore, as the (meth)acrylate polymer, commercially available polymers such as "Kane Ace PA20" and "Kane Ace PA101" manufactured by Kaneka Corporation can be used. The amount of the processing aid added may be 10 parts by mass or less, 5 parts by mass or less, or 0.01 to 3 parts by mass per 100 parts by mass of the modacrylic resin.

[0052] From the viewpoint of suitable use as artificial hair, the modacrylic fiber may have a single fiber fineness of 10 to 100 dtex, 20 to 90 dtex, or 30 to 75 dtex. In this specification, the single fiber fineness is measured in accordance with JIS L 1013.

[0053] The apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber is not particularly limited, but is preferably 83.0 to 97°C, more preferably 83.5 to 96.5°C, and even more preferably 84.0 to 96.0°C. When the apparent glass transition temperature of the modacrylic fiber is 97.0°C or lower, the curl setting ability in hot water at 45 to 65°C can be further improved. Furthermore, when the apparent glass transition temperature of the modacrylic fiber is 83.0°C or higher, the curl retention ability at room temperature (e.g., 5 to 40°C) can be improved. In this specification, the apparent glass transition temperature of the modacrylic fiber can be measured as described in the Examples.

[0054] The temperature at which 1 / 10 of the apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber rises is not particularly limited, but from the viewpoint of further improving curl retention at room temperature (e.g., 5 to 40°C), it is, for example, preferably 52°C or higher, more preferably 53°C or higher, even more preferably 54°C or higher, and even more preferably 55°C or higher. The upper limit of the temperature at which 1 / 10 of the apparent glass transition temperature (peak temperature of Tan δ) of the modacrylic fiber rises is not particularly limited, but may be, for example, 65.0°C or lower. In this specification, the temperature at which 1 / 10 of the apparent glass transition temperature of the modacrylic fiber rises can be measured as described in the Examples.

[0055] From the viewpoint of excellent curl settability with low-temperature hot water, the modacrylic fiber preferably has a curl set rate of 45% or less, and even more preferably 40% or less, when set with hot water at 65° C., and even more preferably 55% or less, and even more preferably 50% or less, when set with hot water at 55° C., and even more preferably 65% ​​or less, and even more preferably 60% or less, when set with hot water at 45° C. In this specification, the curl set rate with hot water can be measured as described in the Examples.

[0056] From the viewpoint of excellent curl retention, the modacrylic fiber preferably has an elongation of 22% or less, more preferably 20% or less, and even more preferably 18% or less, after being curl-set with hot water at a low temperature of 45 to 65°C and then kept at room temperature (5 to 40°C) and room humidity (relative humidity 45 to 85%), more specifically at a temperature of 25°C and a relative humidity of 50%, for 7 days. In this specification, the elongation after curl setting with hot water can be measured as described in the Examples.

[0057] (Method for producing modacrylic fiber) The modacrylic fiber can be produced by melt-spinning a resin composition containing the modacrylic resin and drawing the resulting undrawn yarn. The resin composition may contain the plasticizer, stabilizer, lubricant, and other additives described above, and these are preferably contained within the ranges described in the description of the modacrylic fiber.

[0058] For ease of operation, for example, the modacrylic resin and the plasticizer can be mixed first. If necessary, the stabilizer, the lubricant, the processing aid, etc. are also mixed. For the mixing, a mixer such as a Henschel mixer, a super mixer, or a ribbon blender can be used, although it is not particularly limited.

[0059] Next, the powder mixture can be melt-kneaded. The temperature during kneading is not particularly limited, but may be, for example, 40 to 200°C, 80 to 185°C, or 100 to 165°C from the viewpoint of melt-kneading properties and preventing discoloration. For kneading, a kneading device such as a single-screw extruder, a twin-screw extruder, or a plastomill can be used, but is not particularly limited. By melt-kneading the powder mixture, a modacrylic resin composition in the form of strands or pellets can be obtained.

[0060] Next, the pelletized modacrylic resin composition is melt-spun to obtain an undrawn yarn. Specifically, the pelletized modacrylic resin composition is melted in an extruder, such as a single-screw extruder, a counter-rotating twin-screw extruder, or a conical twin-screw extruder, and extruded through a spinning nozzle. If necessary, the extruded material is passed through a heating tube, and then cooled to a temperature below the glass transition point using cooling means such as air cooling or wind cooling. This allows the extruder to operate at a cylinder temperature of, for example, 20 to 200°C. The ratio of the take-up speed to the discharge speed (also referred to as nozzle draft) is not particularly limited. For example, the undrawn yarn may be taken up at a nozzle draft of 1 to 100 times. From the viewpoint of spinning stability, it is preferable to take up the undrawn yarn at a nozzle draft of 5 to 50 times. The diameter of the spinning nozzle is not particularly limited, but may be, for example, 0.05 to 2 mm or 0.1 to 1 mm in the case of a circular nozzle. The material extruded from the spinning nozzle is preferably extruded at a nozzle temperature at which melt fracture does not occur, and the temperature of the spinning nozzle is preferably 160 to 300°C, and may be 180 to 260°C, for example.

[0061] The undrawn yarn obtained above can be drawn to obtain a drawn yarn (modacrylic fiber). The drawing process may be dry or wet. The drawing temperature may be, for example, 70 to 150°C or 80 to 140°C. The draw ratio may be approximately 110 to 600% or 150 to 450%. Here, the draw ratio (%) is expressed as (fiber length of drawn yarn / fiber length of undrawn yarn) x 100. The drawn yarn may be subjected to a relaxation treatment as needed. The drawn fiber (drawn yarn) may be subjected to a relaxation treatment at 70 to 150°C or 80 to 140°C at a relaxation rate of, for example, approximately 1 to 50% or approximately 5 to 40%, thereby reducing the thermal shrinkage rate. Furthermore, heat relaxation is preferred to smooth out the irregularities on the fiber surface and achieve a smooth texture similar to that of human hair.

[0062] (Headwearing Products) The modacrylic fiber may be used alone as artificial hair to replace human hair, or may be used in combination with other artificial hair fibers. Headwearing products may be composed solely of the modacrylic fiber, or may be composed of the modacrylic fiber in combination with other artificial hair fibers. This makes it possible to provide headwearing products that have excellent curl setting properties in hot water at 45 to 65°C and good curl retention at room temperature (e.g., 5 to 40°C). Other artificial hair fibers are not particularly limited, but examples include polyvinyl chloride fibers, nylon fibers, polyester fibers, and regenerated collagen fibers.

[0063] Headwear products include, but are not limited to, weaving, wigs, braids, toupees, hair extensions, and hair accessories.

[0064] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0065] First, various measurement and evaluation methods will be described. (1) Mass-average molecular weight and number-average molecular weight: The mass-average molecular weight and number-average molecular weight of the compound were measured and calculated by GPC using gel permeation chromatography ("HLC-8320GPC" manufactured by Tosoh Corporation). Polystyrene was used as the standard polymer, and chloroform was used as the mobile phase (eluent) for macromonomers, and dimethylformamide was used as the mobile phase (eluent) for modacrylic resins. (2) Specific viscosity ηsp: 1.0 g of modacrylic resin (graft copolymer) was dissolved in 500 mL of dimethylformamide, and the specific viscosity ηsp of the modacrylic resin solution was measured at 30°C using an Ostwald viscometer. (3) Apparent glass transition temperature (peak temperature of Tan δ): The apparent glass transition temperature (peak temperature of Tan δ) of modacrylic fiber is the temperature at which the dynamic viscoelasticity (tan δ) reaches its maximum value. Using a thermal analysis measuring device (Seiko Electronics, Model "SSC / 5200"), the loss elasticity (E") and storage elasticity (E') of the fiber were measured in accordance with JIS K 7244 under conditions of a vibration frequency of 0.05 Hz, a load of 25 mN±10 mN, and a heating rate of 5°C / min. The dynamic viscoelasticity (tan δ) was calculated using the following formula, and the temperature at which the dynamic viscoelasticity (tan δ) reached its maximum value was defined as the peak temperature of tan δ (apparent glass transition temperature). Dynamic viscoelasticity (tan δ) = loss elasticity (E") / storage elasticity (E') (4) Temperature at which the apparent glass transition temperature (peak temperature of tan δ) rose by 1 / 10 The temperature at which the value of tan δ rose by 1 / 10 (10%) relative to the maximum value of tan δ at 35°C was measured. (5) Evaluation of curl setting in hot water Modacrylic fiber (total fineness approximately 7400 dtex) was cut to a length of 28 cm (L0), and the resulting fiber bundle was wound around a pipe with a diameter of 15 mm and fixed. The fiber bundle was immersed in hot water at a predetermined temperature for 60 seconds and then allowed to dry at room temperature. The length (L1) of the fiber bundle immediately after removal from the pipe was measured. The length (L2) of the fiber bundle was then measured after being kept in an atmosphere at a temperature of 25°C and a relative humidity of 50% for 7 days. The set ratio and elongation were calculated based on the following formula. A lower set ratio indicates better settability, and a lower elongation indicates better retention.Set ratio (%) = L1 / L0 * 100 Elongation (%) = (L2 - L1) / L0 * 100 (6) Touch The touch of the modacrylic fiber was evaluated sensorily using the following four-level scale: A: No stickiness, very good touch B: Almost no stickiness, good touch C: Slight stickiness, slightly poor touch D: Stickiness, poor touch (7) Spinning time According to the procedure for melt spinning modacrylic fiber described below, a modacrylic resin composition was melted and extruded from a circular spinning nozzle with 12 holes, and taken up at a nozzle draft of 6.8 times to obtain an undrawn yarn of about 150 dtex. The time required for winding at any of the 12 holes without yarn breakage, i.e., the time from the start of winding until yarn breakage occurred, was measured, and the average time from three runs was taken as the spinning time.

[0066] (Production Example 1) A reaction vessel was charged with 40 parts by mass of 2-methoxyethyl acrylate, 12 parts by mass of methanol (MeOH), 3.33 parts by mass of ethyl 2-bromobutyrate, and 0.18 parts by mass of triethylamine, and the charged raw materials were stirred at 40°C under a nitrogen atmosphere. Next, 0.0191 parts by mass of copper (II) bromide (CuBr2) was dissolved in 8 parts by mass of methanol and added to 0.0197 parts by mass of hexamethyltris(2-aminoethyl)amine (Me6TREN), and then added to the reaction vessel, and the raw materials in the reaction vessel were mixed. Furthermore, 0.015 parts by mass of ascorbic acid and 0.017 parts by mass of triethylamine were mixed with 3.0 parts by mass of methanol, and the resulting ascorbic acid solution was added dropwise to the reaction vessel to initiate polymerization. During the polymerization, the reaction solution was heated and stirred while adjusting the dropwise addition rate of the ascorbic acid solution so that the temperature of the reaction solution was 40 to 60°C. Sixty minutes after the start of the dropwise addition of the ascorbic acid solution, when the monomer consumption rate in the reaction vessel reached 37% (total monomer consumption rate 15%), 60 parts by mass of 2-methoxyethyl acrylate was added dropwise to the reaction vessel over 60 minutes. The reaction solution was then continued to be heated and stirred while adjusting the rate of addition of the ascorbic acid solution into the reaction vessel so that the temperature of the reaction vessel remained at 40 to 60°C. 310 minutes after the start of the dropwise addition of the ascorbic acid solution, when the monomer consumption rate in the reaction vessel reached 95%, the dropwise addition of ascorbic acid was stopped, and the polymerization reaction was terminated. The resulting reaction product was diluted with toluene, passed through an activated alumina column, and the volatiles were removed by vacuum distillation to obtain poly(2-methoxyethyl acrylate) with a Br group at one end. 100 parts by mass of poly(2-methoxyethyl acrylate) with a Br group at one end was charged to a flask and diluted with 100 parts by mass of dimethylacetamide. 3.9 parts by mass of potassium acrylate was added, and the mixture was heated and stirred at 70°C for 3 hours. Thereafter, dimethylacetamide was distilled off from the reaction mixture, the reaction mixture was dissolved in toluene, and the solution was passed through an activated alumina column, after which the toluene was distilled off to obtain a poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end. The number-average molecular weight of the obtained poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end was 6,000, and the molecular weight distribution (mass-average molecular weight / number-average molecular weight) was 1.2.

[0067] Example 1 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 47 parts by mass of vinyl chloride, 7.5 parts by mass of acrylonitrile, 3 parts by mass of poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 5 parts by mass of vinyl acetate, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes while the internal temperature of the polymerization reactor was cooled to 15° C. or below. Thereafter, the internal temperature of the polymerization reactor was raised to 45° C. to initiate polymerization, and suspension polymerization was carried out at 50° C. for 4 hours, then at 52.5° C. for a further 2 hours, and then at 55° C. for a further 2 hours. During the polymerization, 37.5 parts by mass of acrylonitrile and 0.50 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of polymerization until the 7th hour. After recovering the unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer (thermoplastic modacrylic resin). The resulting graft copolymer had a backbone polymer of acrylonitrile, vinyl chloride, and vinyl acetate, and poly(2-methoxyethyl acrylate) as a branch polymer. It consisted of 42.1% by mass of structural units derived from acrylonitrile, 49.9% by mass of structural units derived from vinyl chloride, 5.0% by mass of structural units derived from vinyl acetate, and 3.0% by mass of structural units derived from a poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end. The mass average molecular weight was approximately 52,000, the molecular weight distribution (mass average molecular weight / number average molecular weight) was 2.85, and the specific viscosity was 0.110.

[0068] (Preparation of Modacrylic Fiber) To 100 parts by weight of the modacrylic resin obtained above, 0.5 parts by weight of dimethyl sulfone as a plasticizer, 1.5 parts by weight of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., product name "Alcamizer (registered trademark) 1") as stabilizers, 0.3 parts by weight of calcium soap / zinc soap, and 0.4 parts by weight of β-diketone were added, and 0.15 parts by weight of a fatty acid ester lubricant (manufactured by Riken Vitamin Co., Ltd., product name "EW-100") and 0.2 parts by weight of stearic acid (manufactured by NOF Corp., product name "Sakura Stearate") as lubricants, and 0.2 parts by weight of a (meth)acrylate polymer (manufactured by Kaneka Corp., product name "Kane Ace PA20") as an additional additive, were added and mixed using a Henschel mixer to obtain a powder mixture. The powder mixture was then extruded using a laboratory extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number "4C150", combined with a 20 mm extrusion unit and a 2 mm strand nozzle) to obtain strands. The extruder was operated at a temperature range of 110 to 150°C. The obtained strand was air-cooled and then pelletized. The pellets of the modacrylic resin composition obtained above were extruded into a laboratory extruder (Toyo Seiki Co., Ltd., model number "4C150", 20 mm extrusion unit, a downward die for measuring melt viscosity, and a hole cross-sectional area of ​​0.08 mm 2 The melt was extruded and melt spun using a 12-hole circular spinning nozzle (combination of a 12-hole circular spinning nozzle) at a cylinder temperature of 120 to 170°C and a nozzle temperature of 210±20°C. The undrawn yarn was taken up at a nozzle draft of approximately 7.6, yielding an undrawn yarn with a single fiber fineness of approximately 130 dtex. The undrawn yarn was then dry-heat drawn to a draw ratio of 275% in a dry heat atmosphere at 100°C, and subsequently relaxed at a relaxation rate of 5%, yielding a modacrylic fiber with a single fiber fineness of approximately 50 dtex.

[0069] Example 2 (Preparation of Modacrylic Resin) A modacrylic resin was prepared in the same manner as in Example 1. (Preparation of Modacrylic Fiber) Pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the modacrylic resin obtained above was used and the amount of plasticizer (dimethyl sulfone) added was changed to 2.5 parts by mass. The pellets of the modacrylic resin composition obtained above were extruded into a laboratory extruder (manufactured by Toyo Seiki Seisaku-sho, model number "4C150", 20 mm extrusion unit, a downward die for measuring melt viscosity, and a hole cross-sectional area of ​​0.08 mm 2The melt-spun yarn was extruded using a 12-hole circular spinning nozzle (combination of a 12-hole circular spinning nozzle) at a cylinder temperature of 120 to 170°C and a nozzle temperature of 210±20°C. The yarn was taken up at a nozzle draft of approximately 6.8 times, yielding an undrawn yarn with a single fiber fineness of approximately 150 dtex. The undrawn yarn was then dry-heat drawn to a draw ratio of 300% in a dry heat atmosphere at 100°C, and subsequently relaxed at a relaxation rate of 5%, yielding a modacrylic fiber with a single fiber fineness of approximately 52.5 dtex.

[0070] <Example 3> (Preparation of modacrylic resin) A modacrylic resin was prepared in the same manner as in Example 1. (Preparation of modacrylic fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 5.0 parts by mass. A modacrylic fiber having a single fiber fineness of approximately 52.5 dtex was obtained in the same manner as in Example 2, except that the pellets of the modacrylic resin composition obtained above were used.

[0071] Example 4 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 49 parts by mass of vinyl chloride, 7 parts by mass of acrylonitrile, 3 parts by mass of poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes in a state where the internal temperature of the polymerization reactor was cooled to 15° C. or below. Thereafter, the internal temperature of the polymerization reactor was raised to 45° C. to initiate polymerization, and suspension polymerization was carried out at a polymerization temperature of 50° C. for 4 hours, then at 52.5° C. for a further 2 hours, and then at 55° C. for a further 2 hours. During the polymerization, 36 parts by mass of acrylonitrile, 5 parts by mass of 2-hydroxyethyl methacrylate, and 0.50 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of the polymerization until 7 hours later. After recovering unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer (thermoplastic modacrylic resin). The obtained graft copolymer had a copolymer of acrylonitrile, vinyl chloride, and 2-hydroxyethyl methacrylate as the trunk polymer and poly(2-methoxyethyl acrylate) as the branch polymer, and was composed of 42.3% by mass of structural units derived from acrylonitrile, 49.7% by mass of structural units derived from vinyl chloride, 5.0% by mass of structural units derived from 2-hydroxyethyl methacrylate, and 3.0% by mass of structural units derived from poly(2-methoxyethyl acrylate) macromonomers having an acryloyl group at one end, and had a mass average molecular weight of approximately 55,000, a molecular weight distribution (mass average molecular weight / number average molecular weight) of 2.64, and a specific viscosity of 0.111.

[0072] (Preparation of Modacrylic Fiber) Pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the modacrylic resin obtained above was used and the amount of plasticizer (dimethyl sulfone) added was changed to 2.5 parts by mass. An undrawn yarn having a single fiber fineness of approximately 150 dtex was obtained in the same manner as in Example 2, except that the pellets of the modacrylic resin composition obtained above were used. The undrawn yarn obtained was dry-heat drawn to a draw ratio of 225% in a dry heat atmosphere at 100°C, and then subjected to a relaxation treatment at a relaxation rate of 5%, to obtain a modacrylic fiber having a single fiber fineness of approximately 70 dtex.

[0073] Example 5 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 50 parts by mass of vinyl chloride, 7.5 parts by mass of acrylonitrile, 3 parts by mass of poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 2 parts by mass of vinyl acetate, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes while the internal temperature of the polymerization reactor was cooled to 15° C. or below. Thereafter, the internal temperature of the polymerization reactor was raised to 45° C. to initiate polymerization, and suspension polymerization was carried out at 50° C. for 4 hours, then at 52.5° C. for a further 2 hours, and then at 55° C. for a further 2 hours. During the polymerization, 37.5 parts by mass of acrylonitrile and 0.50 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of polymerization until the 7th hour. After recovering the unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer (thermoplastic modacrylic resin). The resulting graft copolymer had a backbone polymer of acrylonitrile, vinyl chloride, and vinyl acetate, and poly(2-methoxyethyl acrylate) as a branch polymer. The resulting graft copolymer consisted of 40.6% by mass of structural units derived from acrylonitrile, 54.4% by mass of structural units derived from vinyl chloride, 2.0% by mass of structural units derived from vinyl acetate, and 3.0% by mass of structural units derived from a poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end. The mass average molecular weight was approximately 46,600, the molecular weight distribution (mass average molecular weight / number average molecular weight) was 2.66, and the specific viscosity was 0.099. (Preparation of Modacrylic Fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 5.0 parts by mass. Modacrylic fiber having a single fiber fineness of about 52.5 dtex was obtained in the same manner as in Example 2, except that the pellets of the modacrylic resin composition obtained above were used.

[0074] Example 6 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 45 parts by mass of vinyl chloride, 7.0 parts by mass of acrylonitrile, 3 parts by mass of poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 8 parts by mass of vinyl acetate, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes while the temperature inside the polymerization reactor was cooled to 15° C. or below. Thereafter, the temperature inside the polymerization reactor was raised to 45° C. to initiate polymerization, and the polymerization temperature was maintained at 50° C. for 4 hours, then raised to 52.5° C. and further 2 hours, and then raised to 55° C. and further 2 hours for suspension polymerization. During the polymerization, 37.0 parts by mass of acrylonitrile and 0.50 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of polymerization until the 7th hour. After recovering the unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer (thermoplastic modacrylic resin). The resulting graft copolymer had a backbone polymer of a copolymer of acrylonitrile, vinyl chloride, and vinyl acetate, and poly(2-methoxyethyl acrylate) as a branch polymer. The resulting graft copolymer consisted of 40.3% by mass of structural units derived from acrylonitrile, 48.7% by mass of structural units derived from vinyl chloride, 8.0% by mass of structural units derived from vinyl acetate, and 3.0% by mass of structural units derived from a poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end. The mass average molecular weight was approximately 51,900, the molecular weight distribution (mass average molecular weight / number average molecular weight) was 2.71, and the specific viscosity was 0.098. (Preparation of Modacrylic Fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 5.0 parts by mass. Modacrylic fiber having a single fiber fineness of about 52.5 dtex was obtained in the same manner as in Example 2, except that the pellets of the modacrylic resin composition obtained above were used.

[0075] Comparative Example 1 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 54 parts by mass of vinyl chloride, 7.5 parts by mass of acrylonitrile, 3 parts by mass of the poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes while the internal temperature of the polymerization reactor was cooled to 15° C. or below. The internal temperature of the polymerization reactor was then raised to 45° C. to initiate polymerization, and suspension polymerization was carried out at 50° C. for 4 hours, then at 52.5° C. for a further 2 hours, and then at 55° C. for a further 2 hours. During the polymerization, 35.5 parts by mass of acrylonitrile and 0.45 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of polymerization until the 7th hour. After recovering unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer. The resulting graft copolymer had a backbone polymer of acrylonitrile and vinyl chloride and poly(2-methoxyethyl acrylate) as a branch polymer. It consisted of 41.8% by mass of structural units derived from acrylonitrile, 55.2% by mass of structural units derived from vinyl chloride, and 3.0% by mass of structural units derived from a poly(2-methoxyethyl acrylate) macromonomer bearing an acryloyl group at one end. The mass-average molecular weight was approximately 48,000, the molecular weight distribution (mass-average molecular weight / number-average molecular weight) was 2.51, and the specific viscosity was 0.102.

[0076] (Preparation of Modacrylic Fiber) Pellets of the modacrylic resin composition were prepared in the same manner as in Example 1, except that the modacrylic resin obtained above was used. The pellets of the modacrylic resin composition obtained above were extruded into a laboratory extruder (manufactured by Toyo Seiki Seisakusho, model number "4C150", 20 mm extrusion unit, a downward die for measuring melt viscosity, and a hole cross-sectional area of ​​0.08 mm 2The melt-spun yarn was extruded using a 12-hole circular spinning nozzle (combination of a 12-hole circular spinning nozzle) at a cylinder temperature of 120 to 170°C and a nozzle temperature of 210±20°C. The yarn was taken up at a nozzle draft of approximately 7.0, yielding an undrawn yarn with a single fiber fineness of approximately 145 dtex. The undrawn yarn was dry-heat drawn to a draw ratio of 300% in a dry heat atmosphere at 100°C, and subsequently relaxed at a relaxation rate of 5%, yielding a modacrylic fiber with a single fiber fineness of approximately 50 dtex.

[0077] <Comparative Example 2> (Preparation of Modacrylic Resin) A modacrylic resin was prepared in the same manner as in Comparative Example 1. (Preparation of Modacrylic Fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Comparative Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 5.0 parts by mass. A modacrylic fiber having a single fiber fineness of about 50 dtex was obtained in the same manner as in Comparative Example 1, except that pellets of the modacrylic resin composition obtained above were used.

[0078] <Comparative Example 3> (Preparation of Modacrylic Resin) A modacrylic resin was prepared in the same manner as in Comparative Example 1. (Preparation of Modacrylic Fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Comparative Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 7.5 parts by mass. A modacrylic fiber having a single fiber fineness of about 50 dtex was obtained in the same manner as in Comparative Example 1, except that pellets of the modacrylic resin composition obtained above were used.

[0079] Comparative Example 4 (Preparation of Modacrylic Resin) A polymerization reactor was charged with 44 parts by mass of vinyl chloride, 7.0 parts by mass of acrylonitrile, 3 parts by mass of poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end obtained in Production Example 1, 10 parts by mass of vinyl acetate, 210 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree: approximately 70 mol %, average polymerization degree: 1700), and 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and the mixture was stirred and dispersed for 15 minutes while the internal temperature of the polymerization reactor was cooled to 15° C. or below. Thereafter, the internal temperature of the polymerization reactor was raised to 45° C. to initiate polymerization, and suspension polymerization was carried out at 50° C. for 4 hours, then at 52.5° C. for a further 2 hours, and then at 55° C. for a further 2 hours. During the polymerization, 36.0 parts by mass of acrylonitrile and 0.50 parts by mass of 2-mercaptoethanol were continuously added at a constant rate from immediately after the start of polymerization until the 7th hour. After recovering the unreacted monomers from the polymerization reactor, the slurry was discharged. The resulting slurry was dehydrated and dried in a hot air dryer at 60°C for 24 hours to obtain a graft copolymer (thermoplastic modacrylic resin). The resulting graft copolymer had a copolymer of acrylonitrile, vinyl chloride, and vinyl acetate as the trunk polymer and poly(2-methoxyethyl acrylate) as the branch polymer. It consisted of 39.6% by mass of structural units derived from acrylonitrile, 47.4% by mass of structural units derived from vinyl chloride, 10.0% by mass of structural units derived from vinyl acetate, and 3.0% by mass of structural units derived from a poly(2-methoxyethyl acrylate) macromonomer having an acryloyl group at one end. The mass average molecular weight was approximately 53,400, the molecular weight distribution (mass average molecular weight / number average molecular weight) was 2.74, and the specific viscosity was 0.111. (Preparation of Modacrylic Fiber) Using the modacrylic resin obtained above, pellets of a modacrylic resin composition were prepared in the same manner as in Example 1, except that the amount of plasticizer (dimethyl sulfone) added was 5.0 parts by mass. An undrawn yarn having a single fiber fineness of about 150 dtex was obtained in the same manner as in Example 2, except that the pellets of the modacrylic resin composition obtained above were used.When the obtained undrawn yarn was dry-heat drawn to a draw ratio of 300% in a dry-heat atmosphere at 100° C., hardening of the fiber occurred, and a drawn yarn (modacrylic fiber) could not be obtained.

[0080] The modacrylic fibers obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated for curl setting in hot water and texture as described above, and the results are shown in Table 1 below. The apparent glass transition temperature, 1 / 10 increase temperature of the apparent glass transition temperature, and spinning time of the modacrylic fibers obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were also measured as described above, and the results are shown in Table 1 below. In Table 1 below, Tan δMAX indicates the apparent glass transition temperature, the 1 / 10 increase temperature of Tan δMAX indicates the 1 / 10 increase temperature of the apparent glass transition temperature, and the amount of plasticizer added is based on 100 parts by mass of the modacrylic resin.

[0081]

[0082] As can be seen from Table 1 above, the modacrylic fibers of Examples 1 to 6, which used a modacrylic resin (graft copolymer) containing structural units derived from a carboxylic acid ester monomer, had a lower curl set ratio when set in hot water at a low temperature, specifically, a temperature of 45 to 65°C, and a higher curl setability when set in hot water at a low temperature, compared to the modacrylic fiber of Comparative Example 1, which contained a modacrylic resin not containing structural units derived from a carboxylic acid ester monomer and had a plasticizer content of 0.5 parts by mass per 100 parts by mass of the modacrylic resin. Furthermore, the modacrylic fibers of Examples 1 to 4, which used a modacrylic resin containing structural units derived from a carboxylic acid ester monomer, had a lower elongation after curl set in hot water at 45°C and 65°C, and a higher curl retention when set in hot water at a low temperature, compared to the modacrylic fiber of Comparative Example 2, which contained a modacrylic resin not containing structural units derived from a carboxylic acid ester monomer and had a plasticizer content of 5 parts by mass per 100 parts by mass of the modacrylic resin. Furthermore, the modacrylic fibers of Examples 5 and 6, which used modacrylic resins containing structural units derived from carboxylic acid ester monomers, had lower elongation after curl setting with low-temperature hot water at 55°C and better curl retention after curl setting with low-temperature hot water than the modacrylic fiber of Comparative Example 2. The modacrylic fibers of Examples 1 to 6 had a good feel, while the modacrylic fiber of Comparative Example 2 had a slightly poor feel. The modacrylic fibers of Examples 1 to 4, which used modacrylic resins containing structural units derived from carboxylic acid ester monomers, had lower elongation after curl setting with low-temperature hot water at 45°C and better curl retention after curl setting with low-temperature hot water than the modacrylic fiber of Comparative Example 3, which contained a modacrylic resin not containing structural units derived from carboxylic acid ester monomers and contained 7.5 parts by mass of plasticizer per 100 parts by mass of modacrylic resin. The modacrylic fibers of Examples 1 to 4 had a good feel, while the modacrylic fiber of Comparative Example 3 had a poor feel. Furthermore, since the modacrylic fiber of Comparative Example 3 contains a large amount of plasticizer, its apparent glass transition temperature is less than 80°C, which raises concerns about a deterioration in the heat resistance of the fiber. Specifically, the processing temperature under dry heat is lowered, which may make it difficult to curl or crimp the fiber under dry heat.In Comparative Example 4, which used a modacrylic resin containing a large amount of structural units derived from carboxylic acid ester monomers, the undrawn yarn (fiber) hardened during drawing, making it impossible to obtain a drawn yarn. This is presumably because the modacrylic resin contains a large amount of structural units derived from carboxylic acid ester monomers, which significantly reduces the glass transition temperature under dry heat.

[0083] As can be seen from a comparison of Examples 1 to 3, 5, and 6 with Example 4, Examples 1 to 3, 5, and 6, which used a vinyl ester as the carboxylic acid ester monomer, had longer spinning times and better spinnability than Example 4, which used a hydroxyalkyl (meth)acrylate as the carboxylic acid ester monomer. Furthermore, the modacrylic fiber of Example 4, which used a hydroxyalkyl (meth)acrylate as the carboxylic acid ester monomer, tended to harden during curl setting with hot water at 65°C, while the modacrylic fibers of Examples 1 to 3, 5, and 6, which used a vinyl ester as the carboxylic acid ester monomer, exhibited better curl setting and retention during curl setting with hot water at a lower temperature.

[0084] The present invention is not particularly limited, but it is desirable to include, for example, the following embodiments.

[0085] [1] A modacrylic fiber containing a modacrylic resin, wherein the modacrylic resin is a graft copolymer containing 35 to 84% by mass of structural units derived from acrylonitrile, 15 to 64% by mass of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5% by mass of structural units derived from carboxylic acid ester monomers, and 0.5 to 40% by mass of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, wherein the carboxylic acid ester monomer is at least one selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters. [2] The modacrylic fiber according to [1], wherein the carboxylic acid ester monomer is a vinyl ester. [3] The modacrylic fiber according to [1] or [2], wherein the vinyl ester includes at least one selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate. [4] The modacrylic fiber according to any one of [1] to [3], wherein the ethylenically unsaturated monomer is at least one selected from the group consisting of (meth)acrylic acid ester monomers, styrene monomers, nitrile group-containing vinyl monomers, amide group-containing vinyl monomers, silicon-containing vinyl monomers, maleimide monomers, vinyl esters, alkenes, conjugated dienes, maleic anhydride, maleic acid, monoalkyl esters of maleic acid, dialkyl esters of maleic acid, fumaric acid, monoalkyl esters of fumaric acid, dialkyl esters of fumaric acid, allyl chloride, and allyl alcohol. [5] The modacrylic fiber according to any one of [1] to [4], wherein the modacrylic fiber contains 0.3 to 7 parts by mass of a plasticizer per 100 parts by mass of the modacrylic polymer. [6] The modacrylic fiber according to any one of [1] to [5], wherein the macromonomer has a number-average molecular weight of 2,000 to 20,000. [7] The modacrylic fiber according to any one of [1] to [6], wherein the modacrylic fiber has a single fiber fineness of 10 to 100 dtex. [8] The modacrylic fiber according to any one of [1] to [7], wherein the modacrylic fiber has an apparent glass transition temperature (Tan δ peak temperature) of 1 / 10 of 52.0°C or higher.[9] A head ornament comprising the modacrylic fiber according to any one of [1] to [8].

[10] A method for producing the modacrylic fiber according to any one of [1] to [8], comprising the steps of melt-spinning a resin composition comprising a modacrylic resin to obtain an undrawn yarn, and drawing the undrawn yarn, wherein the modacrylic resin is a graft copolymer comprising 35 to 84 mass% of structural units derived from acrylonitrile, 15 to 64 mass% of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5 mass% of structural units derived from a carboxylic acid ester monomer, and 0.5 to 40 mass% of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, and the carboxylic acid ester monomer is one or more selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters.

[11] The method for producing a modacrylic fiber according to

[10] , wherein the resin composition contains 0.5 to 7 parts by mass of a plasticizer relative to 100 parts by mass of the graft copolymer.

Claims

1. A modacrylic fiber comprising a modacrylic resin, the modacrylic resin being a graft copolymer containing 35 to 84 mass% of structural units derived from acrylonitrile, 15 to 64 mass% of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5 mass% of structural units derived from a carboxylic acid ester monomer, and 0.5 to 40 mass% of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, and the carboxylic acid ester monomer is one or more selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters.

2. The modacrylic fiber according to claim 1, wherein the carboxylic acid ester monomer is a vinyl ester.

3. The modacrylic fiber of claim 1, wherein the vinyl ester comprises one or more selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate.

4. The modacrylic fiber according to claim 1, wherein the ethylenically unsaturated monomer comprises one or more selected from the group consisting of (meth)acrylic acid ester monomers, styrene monomers, nitrile group-containing vinyl monomers, amide group-containing vinyl monomers, silicon-containing vinyl monomers, maleimide monomers, vinyl esters, alkenes, conjugated dienes, maleic anhydride, maleic acid, monoalkyl esters of maleic acid, dialkyl esters of maleic acid, fumaric acid, monoalkyl esters of fumaric acid, dialkyl esters of fumaric acid, allyl chloride, and allyl alcohol.

5. The modacrylic fiber according to claim 1, which contains 0.3 to 7 parts by weight of a plasticizer per 100 parts by weight of the modacrylic polymer.

6. The modacrylic fiber according to claim 1, wherein the macromonomer has a number average molecular weight of 2,000 to 20,000.

7. The modacrylic fiber according to claim 1, wherein the modacrylic fiber has a single fiber fineness of 10 to 100 dtex.

8. The modacrylic fiber according to claim 1, wherein the modacrylic fiber has an apparent glass transition temperature (peak temperature of Tan δ) of 1 / 10 of the increase in temperature of 52.0°C or higher.

9. A head accessory comprising the modacrylic fiber according to any one of claims 1 to 8.

10. A method for producing a modacrylic fiber according to any one of claims 1 to 8, comprising the steps of: melt-spinning a resin composition containing a modacrylic resin to obtain an undrawn yarn; and drawing the undrawn yarn, wherein the modacrylic resin is a graft copolymer containing 35 to 84% by mass of structural units derived from acrylonitrile, 15 to 64% by mass of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, 0.5 to 9.5% by mass of structural units derived from a carboxylic acid ester monomer, and 0.5 to 40% by mass of structural units derived from a macromonomer having in its main chain a polymer composed of an ethylenically unsaturated monomer, and the carboxylic acid ester monomer is one or more selected from the group consisting of vinyl esters and (meth)acrylic acid hydroxyalkyl esters.

11. The method for producing modacrylic fiber according to claim 10, wherein the resin composition contains 0.3 to 7 parts by mass of a plasticizer per 100 parts by mass of the modacrylic resin.

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