Carbon fiber precursor treating agent and carbon fiber precursor

Abstract

The present invention aims to provide a carbon fiber precursor treatment agent and a carbon fiber precursor that can reduce burrs in flame-resistant fibers. The carbon fiber precursor treatment agent of the present invention is characterized in that it contains a smoothing agent (A) comprising an ester compound (A1) of glycerol and a fatty acid comprising the following fatty acid (X), and a (poly)oxyalkylene derivative (B). The ester compound (A1) is an ester compound (A1) of glycerol and a fatty acid comprising the following fatty acid (X). In the carbon fiber precursor treatment agent, the ratio of the total mass of fatty acids having 16 to 24 carbon atoms derived from the ester compound (A1) relative to the total mass of fatty acids derived from the ester compound (A1) is 50% by mass or more. The fatty acid (X) is a fatty acid having 16 to 24 carbon atoms.

Description

Technical Field

[0001] The present invention relates to a carbon fiber precursor treating agent capable of reducing burrs of flame-resistant fibers, and a carbon fiber precursor obtained therefrom. Background Art

[0002] Carbon fibers are commonly used in various fields, such as building materials and transportation equipment, as carbon fiber composite materials or flame-retardant and fire-proof materials, typically combined with matrix resins. For example, carbon fiber precursors are manufactured through a process involving spinning acrylic fibers, stretching the fibers, making them flame-resistant, and carbonizing them. A carbon fiber precursor treatment agent is sometimes used to impart bundling properties during the spinning process.

[0003] A conventionally known treatment agent for carbon fiber precursors is disclosed in Patent Document 1. Patent Document 1 discloses an acrylic synthetic fiber treatment agent comprising, in predetermined proportions, a polyoxyalkylene block copolymer obtained by addition-polymerizing an alkylene oxide to an aliphatic hydroxy compound having a hydroxyl group, an oil or fat primarily composed of a glycerol ester having a fatty acid residue having 12 to 22 carbon atoms, and a predetermined polyoxyethylene glycol alkenyl ether.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-88654 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, conventional carbon fiber precursor treating agents have a problem in that after the carbon fiber precursor to which the carbon fiber precursor treating agent has been applied is subjected to flame retardant treatment, the effect of reducing burrs of the flame retardant fiber is insufficient.

[0009] Means for solving problems

[0010] The present inventors have conducted studies to solve the above-mentioned problems and have found that a treatment agent for a carbon fiber precursor containing a predetermined ester compound and a (poly)oxyalkylene derivative is exactly suitable.

[0011] In order to solve the above-mentioned problems, the key point of the carbon fiber precursor treatment agent of one embodiment of the present invention is that it contains a smoothing agent (A) and a (poly)oxyalkylene derivative (B), wherein the smoothing agent (A) contains an ester compound (A1) of glycerol and a fatty acid containing the following fatty acid (X), and the composition ratio of the fatty acid (X) calculated by the following mathematical formula 1 is 50% by mass or more.

[0012] Fatty acid (X): a fatty acid having 16 to 24 carbon atoms.

[0013] [Number 1]

[0014]

[0015] In the above-mentioned carbon fiber precursor treating agent, the constituent ratio of the fatty acid (X) calculated from the above-mentioned Mathematical Formula 1 may be 70% by mass or more.

[0016] In the carbon fiber precursor treatment agent, the (poly)oxyalkylene derivative (B) may include a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an ester compound of a monovalent to trivalent alcohol and a monovalent fatty acid having 16 to 24 carbon atoms.

[0017] In the above-mentioned carbon fiber precursor treatment agent, when the total content ratio of the above-mentioned smoothing agent (A) and the above-mentioned (poly)oxyalkylene derivative (B) is set to 100 mass%, the above-mentioned smoothing agent (A) can be contained in a ratio of 10 mass% to 90 mass%, and the above-mentioned (poly)oxyalkylene derivative (B) can be contained in a ratio of 10 mass% to 90 mass%.

[0018] The above-mentioned carbon fiber precursor treating agent may further contain a condensed hydroxy fatty acid (C).

[0019] In the above-mentioned carbon fiber precursor treatment agent, when the total content ratio of the above-mentioned smoothing agent (A), the above-mentioned (poly)oxyalkylene derivative (B), and the above-mentioned condensed hydroxy fatty acid (C) is set to 100 mass%, the above-mentioned smoothing agent (A) can be contained in a ratio of 9.9 mass% to 89.9 mass%, the above-mentioned (poly)oxyalkylene derivative (B) can be contained in a ratio of 10 mass% to 90 mass%, and the above-mentioned condensed hydroxy fatty acid (C) can be contained in a ratio of 0.1 mass% to 50 mass%.

[0020] The above-mentioned carbon fiber precursor treating agent may further contain an ionic component (D).

[0021] The above-mentioned carbon fiber precursor treating agent may further contain a condensed hydroxy fatty acid (C) and an ionic component (D).

[0022] In the above-mentioned carbon fiber precursor treatment agent, when the total content ratio of the above-mentioned smoothing agent (A), the above-mentioned (poly)oxyalkylene derivative (B), the above-mentioned condensed hydroxy fatty acid (C), and the above-mentioned ionic component (D) is set to 100 mass%, the above-mentioned smoothing agent (A) can be contained at a ratio of 9.9 mass% to 89.9 mass%, the above-mentioned (poly)oxyalkylene derivative (B) can be contained at a ratio of 9.9 mass% to 89.9 mass%, the above-mentioned condensed hydroxy fatty acid (C) can be contained at a ratio of 0.1 mass% to 50 mass%, and the above-mentioned ionic component can be contained at a ratio of 0.1 mass% to 10 mass%.

[0023] In order to solve the above-mentioned problems, a carbon fiber precursor according to another embodiment of the present invention is characterized in that the above-mentioned carbon fiber precursor treating agent is adhered thereto.

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to reduce burrs in flame-resistant fibers obtained by subjecting a carbon fiber precursor to a treatment agent for a carbon fiber precursor and subjecting it to a flame-resistant treatment. DETAILED DESCRIPTION

[0026] <First embodiment>

[0027] The first embodiment of the carbon fiber precursor treatment agent (hereinafter also referred to simply as the treatment agent) of the present invention is described below. The treatment agent of this embodiment contains a smoothing agent (A) containing the following ester compound (A1) and a (poly)oxyalkylene derivative (B).

[0028] (Smoothing agent (A))

[0029] The smoothing agent (A) provided in this embodiment includes an ester compound (A1), which is an ester compound of glycerol and a fatty acid including the following fatty acid (X). The fatty acid (X) is a fatty acid having 16 or more and 24 or less carbon atoms. As the fatty acid constituting the ester compound (A1), a known substance can be suitably adopted, and it can be a saturated fatty acid or an unsaturated fatty acid. In addition, it can be a straight-chain fatty acid or a fatty acid having a branched structure. The fatty acid can be a monocarboxylic acid or a polycarboxylic acid. In addition, it can be a hydroxycarboxylic acid having a hydroxyl group.

[0030] Specific examples of saturated fatty acids include hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), behenic acid (behenic acid), and tetracosanoic acid. Specific examples of unsaturated fatty acids include palmitoleic acid, oleic acid, vaccenic acid, eicosenoic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, and arachidonic acid. Specific examples of hydroxycarboxylic acids include ricinoleic acid.

[0031] In the ester compound (A1), the constituent ratio of the fatty acid (X) calculated from the following formula is 50% by mass or more, preferably 70% by mass or more. By limiting the numerical range to this range, the effects of the present invention can be further enhanced.

[0032] [Number 2]

[0033]

[0034] Specific examples of the ester compound (A1) include castor oil (the value of the above formula is 100% by mass), rapeseed oil (the value of the above formula is 100% by mass), sesame oil (the value of the above formula is 100% by mass), palm oil (the value of the above formula is 99% by mass), linseed oil (the value of the above formula is 100% by mass), sunflower oil (the value of the above formula is 100% by mass), ester compounds of glycerol, ricinoleic acid and other fatty acids, wherein the value of the above formula is 50% by mass or more, ester compounds of glycerol, palmitic acid and other fatty acids, wherein the value of the above formula is 50% by mass or more, and ester compounds of glycerol, oleic acid and other fatty acids, wherein the value of the above formula is 50% by mass or more.

[0035] These ester compounds (A1) may be used alone or in combination of two or more.

[0036] The lower limit of the content of the ester compound (A1) in the treatment agent can be appropriately set, preferably 5% by mass or more, more preferably 10% by mass or more. When the content is 5% by mass or more, the burrs of the flame-retardant fiber after the carbon fiber precursor to which the treatment agent is applied is subjected to flame-retardant treatment can be further reduced. The upper limit of the content of the ester compound (A1) can be appropriately set, preferably 90% by mass or less, more preferably 85% by mass or less. When the content is 90% by mass or less, the stability of the treatment agent can be improved. It should be noted that a range formed by arbitrarily combining the above upper and lower limits can also be set.

[0037] The smoothing agent (A) may contain other smoothing components other than the ester compound (A1) within the scope that does not hinder the effect of the present invention. There is no particular limitation on other smoothing components, and known smoothing agents used in treatment agents can be used. As known smoothing agents, for example, silicone oil, mineral oil, polyolefin, ester compounds other than the above can be cited. It should be noted that, with regard to silicone oil, contamination of the firing furnace may be generated due to its use. Therefore, the amount of silicone oil in the treatment agent is preferably 5% by mass or less, more preferably 1% by mass or less, and further preferably no silicone oil is mixed. The content ratio of the ester compound (A1) in the smoothing agent (A) can be appropriately set within the scope that does not hinder the effect of the present invention, for example, 50% by mass or more and 100% by mass or less, or 80% by mass or more and 100% by mass or less. It should be noted that a range formed by arbitrarily combining the above upper and lower limits can also be set.

[0038] These smoothing agents (A) may be used alone or in combination of two or more.

[0039] ((Poly)oxyalkylene derivative (B))

[0040] The (poly)oxyalkylene derivative (B) used in the present embodiment acts as a surfactant to improve the stability of the treatment agent, thereby improving various functions of the treatment agent.

[0041] Examples of the (poly)oxyalkylene derivative (B) include those having a (poly)oxyalkylene structure obtained by adding alkylene oxide to alcohols or carboxylic acids, ether-ester compounds having a (poly)oxyalkylene structure obtained by adding alkylene oxide to ester compounds of carboxylic acids and polyols, those having a (poly)oxyalkylene structure obtained by adding alkylene oxide to aliphatic amines as amine compounds, those having a (poly)oxyalkylene structure obtained by adding alkylene oxide to fatty amides, and block copolymers of polyoxyethylene chains and polyoxypropylene chains.

[0042] Specific examples of alcohols used as a raw material for the (poly)oxyalkylene derivative (B) include: (1) straight-chain alkyl alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, heptacosanol, octacosanol, nonacosanol, and triacontanol; (2) isopropyl alcohol, isobutyl alcohol, isohexanol, 2-ethylhexanol, isononanol, isodecanol, isotridecanol, isotetradecanol, and isotriacontanol. (1) branched-chain alkyl alcohols such as 1,2-dimethylbenzene, ...

[0043] Specific examples of carboxylic acids used as raw materials for the (poly)oxyalkylene derivative (B) include: (1) linear alkyl carboxylic acids such as octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid, and docosanoic acid; (2) branched alkyl carboxylic acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, and isooctadecanoic acid; (3) linear alkenyl carboxylic acids such as octadecenoic acid, octadecadienoic acid, and octadecatrienoic acid; (4) aromatic carboxylic acids such as benzoic acid; (5) hydroxycarboxylic acids such as ricinoleic acid; and the like.

[0044] Regarding the alkylene oxide used as the raw material for forming the (poly)oxyalkylene structure of the (poly)oxyalkylene derivative (B), an alkylene oxide having a carbon number of 2 or more and 4 or less is preferred. Specific examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, and the like. The number of moles of alkylene oxide added can be appropriately set, preferably 0.1 mole or more and 250 moles or less, more preferably 1 mole or more and 200 moles or less, and further preferably 2 moles or more and 150 moles or less. A range formed by any combination of the above upper and lower limits can also be set. It should be noted that the number of moles of alkylene oxide added represents the number of moles of alkylene oxide relative to 1 mole of the addition target compound put into the raw material. Alkylene oxide can use one alkylene oxide alone, or two or more alkylene oxides can be used in appropriate combination. When two or more alkylene oxides are used, their addition form can be any one of block addition, random addition, and a combination of block addition and random addition, without particular limitation.

[0045] Specific examples of the polyol used as a raw material for the (poly)oxyalkylene derivative (B) include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, glycerol, 2-methyl-2-hydroxymethyl-1,3-propanediol, trimethylolpropane, sorbitan, pentaerythritol, and sorbitol.

[0046] Specific examples of the aliphatic amine used as a raw material for the (poly)oxyalkylene derivative (B) include methylamine, ethylamine, butylamine, octylamine, laurylamine, octadecylamine, octadecenylamine, and coconut amine.

[0047] Specific examples of the fatty amide used as a raw material for the (poly)oxyalkylene derivative (B) include caprylamide, laurylamide, palmitamide, stearylamide, oleylamide, behenylamide, and tetracosylamide.

[0048] The block copolymer of polyoxyethylene chain and polyoxypropylene chain is not particularly limited as long as it has a polyoxypropylene chain with low hydrophilicity and a polyoxyethylene chain with high hydrophilicity and has a surface active effect. The number of polyoxyethylene chains and polyoxypropylene chains in the molecule is not particularly limited. For example, it can be a block copolymer containing 1 polyoxypropylene chain and 1 polyoxyethylene chain, or it can be a poloxamer surfactant containing a polyoxypropylene chain and 2 polyoxyethylene chains sandwiched therebetween. The number of moles of ethylene oxide added to form the polyoxyethylene chain is not particularly limited. For example, more than 5 moles and less than 200 moles can be cited. The number of moles of propylene oxide added to form the polyoxypropylene chain is not particularly limited. For example, more than 5 moles and less than 100 moles can be cited.

[0049] Among these, preferred are compounds obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an ester compound of a monohydric alcohol or a trivalent or lower polyhydric alcohol and a monovalent fatty acid having 16 to 24 carbon atoms. Use of such compounds can further improve the stability of the treatment agent.

[0050] Specific examples of the (poly)oxyalkylene derivative (B) include: ω-hydroxy(polyoxyethylene) (n=7: represents the number of moles of ethylene oxide added (the same applies hereinafter)) castor oil; ω-hydroxy(polyoxyethylene) (n=20) hydrogenated castor oil, hydroxy(polyoxypropylenepolyoxyethylene) (m=13: represents the number of moles of propylene oxide added (the same applies hereinafter), n=10) castor oil; hydroxy(polyoxypropylenepolyoxyethylene) (m=12, n=12) hydrogenated castor oil; an ethylene oxide adduct of an oil and fat obtained by adding 200 mol of ethylene oxide to 1 mol of castor oil; α-dodecyl-ω-hydroxy(polyoxyethylene) ( n=7); a polyoxyalkylene block copolymer having a number average molecular weight of 5,000 formed by block addition polymerization of ethylene oxide and propylene oxide to ethylene glycol, wherein the polyoxyalkylene block copolymer comprises an ethylene oxide unit / propylene oxide unit ratio of 30 / 70 (molar ratio); a polyoxyalkylene block copolymer having a number average molecular weight of 10,000 formed by block addition polymerization of ethylene oxide and propylene oxide to ethylene glycol, wherein the polyoxyalkylene block copolymer comprises an ethylene oxide unit / propylene oxide unit ratio of 70 / 30 (molar ratio); polyoxyethylene glycol octadecenyl ether having a repeating number of 20 ethylene oxide units; and the like.

[0051] Among these (poly)oxyalkylene derivatives (B), one kind of (poly)oxyalkylene derivative may be used alone, or two or more kinds of (poly)oxyalkylene derivatives may be used in appropriate combination.

[0052] The lower limit of the content of the (poly)oxyalkylene derivative (B) in the treatment agent can be appropriately set, preferably 5% by mass or more, more preferably 10% by mass or more. When the content is 5% by mass or more, the stability of the treatment agent can be further improved. The upper limit of the content of the (poly)oxyalkylene derivative (B) can be appropriately set, preferably 95% by mass or less, more preferably 90% by mass or less. When the content is 95% by mass or less, the burrs of the flame-resistant fiber after the carbon fiber precursor to which the treatment agent is applied is flame-resistant can be further reduced. It should be noted that a range formed by arbitrarily combining the above upper and lower limits can also be set.

[0053] When the total content of the smoothing agent (A) and the (poly)oxyalkylene derivative (B) in the treatment agent is 100 mass%, it is preferred that the smoothing agent (A) be contained in a ratio of 10 mass% to 90 mass%, and the (poly)oxyalkylene derivative (B) be contained in a ratio of 10 mass% to 90 mass%. By limiting the content to this range, the effects of the present invention can be further enhanced.

[0054] (Condensed hydroxy fatty acid (C))

[0055] The treatment agent may further contain a condensed hydroxy fatty acid (C). The condensed hydroxy fatty acid (C) used in this embodiment can improve the bundling properties of the flame-resistant fibers obtained by subjecting the carbon fiber precursor to the treatment agent to a flame-resistant treatment.

[0056] Condensed hydroxy fatty acid (C) is obtained by, for example, subjecting one or a mixture of two or more hydroxy fatty acids as raw materials to a dehydration condensation reaction under a stream of an inert gas such as nitrogen at 100 ° C or more and 200 ° C or less, for 30 minutes or more and 12 hours or less. Specific examples of hydroxy fatty acids include 12-hydroxy-9-octadecenoic acid (ricinoleic acid), 12-hydroxystearic acid, 16-hydroxyhexadecanoic acid (cadinic acid), 18-hydroxyoctadecanoic acid, 9-hydroxystearic acid, 10-hydroxystearic acid, 12-hydroxydodecanoic acid (juniper acid), 9,10-dihydroxyoctadecanoic acid, castor oil fatty acid, hydrogenated castor oil fatty acid, etc. The degree of condensation of the condensed hydroxy fatty acid can be appropriately set, preferably a dimer or more and a hexamer or less.

[0057] Specific examples of the condensed hydroxy fatty acid (C) include condensed 12-hydroxystearic acid hexamer, condensed castor oil fatty acid dimer, condensed castor oil fatty acid trimer, condensed castor oil fatty acid tetramer, condensed castor oil fatty acid pentamer, and condensed castor oil fatty acid hexamer.

[0058] Among these condensed hydroxy fatty acids (C), one type of condensed hydroxy fatty acid may be used alone, or two or more types of condensed hydroxy fatty acids may be used in appropriate combination.

[0059] The lower limit of the content of the condensed hydroxy fatty acid (C) in the treatment agent can be appropriately set, preferably 0.1% by mass or more, more preferably 0.3% by mass or more. When the content is 0.1% by mass or more, the bundle of the flame-retardant fiber after the flame-retardant treatment of the carbon fiber precursor to which the treatment agent is applied can be further improved. The upper limit of the content of the condensed hydroxy fatty acid (C) can be appropriately set, preferably 60% by mass or less, more preferably 50% by mass or less. When the content is 60% by mass or less, the stability of the treatment agent can be improved. It should be noted that a range formed by arbitrarily combining the above upper and lower limits can also be set.

[0060] When the total content of the smoothing agent (A), the (poly)oxyalkylene derivative (B), and the condensed hydroxy fatty acid (C) in the treatment agent is set to 100 mass%, the smoothing agent (A) is preferably contained in a ratio of 9.9 mass% to 89.9 mass%, the (poly)oxyalkylene derivative (B) is contained in a ratio of 10 mass% to 90 mass%, and the condensed hydroxy fatty acid (C) is contained in a ratio of 0.1 mass% to 50 mass%. By limiting to this range, the effect of the present invention can be further enhanced.

[0061] (Ionic component (D))

[0062] The treatment agent may further contain an ionic component (D). The ionic component (D) used in this embodiment can improve the bundling properties of the flame-resistant fibers obtained by flame-resistant treatment of the carbon fiber precursor treated with the treatment agent. It can also improve the antistatic properties of the flame-resistant fibers. Examples of the ionic component (D) include anionic components and cationic components.

[0063] The anion component refers to an anionic compound, and examples thereof include acids and salts thereof.

[0064] Examples of the acid include inorganic acids, organic acids, fatty acids, alkylsulfonic acids, alkylsulfuric acids, polyoxyalkylene alkylsulfuric acids, alkylphosphates, polyoxyalkylene alkylphosphates, fatty acid sulfates, oil and fat sulfates, and salts thereof.

[0065] Specific examples of the inorganic acid or its salt include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, carbonic acid, sodium hydrogen sulfate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydrogen carbonate, and the like.

[0066] Specific examples of the organic acid include citric acid, tartaric acid, lactic acid, malic acid, succinic acid, fumaric acid, maleic acid, gluconic acid, glucuronic acid, and benzoic acid.

[0067] As fatty acid, known substances can be suitably adopted, and it can be saturated fatty acid or unsaturated fatty acid. In addition, it can be straight-chain fatty acid or fatty acid with branched structure. In addition, it can be monobasic fatty acid or polycarboxylic acid (polyacid).

[0068] Specific examples of saturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid (caprylic acid), caprylic acid (2-ethylhexanoic acid), octanoic acid (caprylic acid), nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), behenic acid (behenic acid), and tetracosanoic acid.

[0069] Specific examples of unsaturated fatty acids include crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, eicosenoic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, and arachidonic acid.

[0070] Specific examples of polycarboxylic acids (polyacids) include: (1) dibasic acids such as succinic acid, fumaric acid, maleic acid, adipic acid, and sebacic acid; (2) tribasic acids such as aconitic acid; (3) aromatic dicarboxylic acids such as benzoic acid, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid; (4) aromatic tricarboxylic acids such as trimellitic acid; (5) aromatic tetracarboxylic acids such as pyromellitic acid; and the like.

[0071] Specific examples of the alkylsulfonic acid include laurylsulfonic acid (dodecylsulfonic acid), myristylsulfonic acid, cetylsulfonic acid, oleylsulfonic acid, stearylsulfonic acid, tetradecanesulfonic acid, dodecylbenzenesulfonic acid, and secondary alkylsulfonic acid (C13-15).

[0072] Specific examples of the alkyl sulfate include lauryl sulfate, oleyl sulfate, and stearyl sulfate.

[0073] Specific examples of the polyoxyalkylene alkylsulfuric acid include polyoxyethylene lauryl ether sulfate, polyoxyalkylene (polyoxyethylene, polyoxypropylene) lauryl ether sulfate, polyoxyethylene lauryl ether sulfate, and polyoxyethylene oleyl ether sulfate.

[0074] Specific examples of the alkyl phosphate include lauryl phosphate, hexadecyl phosphate, octyl phosphate, oleyl phosphate, stearyl phosphate, and 2-ethylhexyl phosphate.

[0075] Specific examples of the polyoxyalkylene alkyl phosphate include polyoxyethylene lauryl ether phosphate, polyoxyethylene cetyl ether phosphate, polyoxyethylene oleyl ether phosphate, and polyoxyethylene stearyl ether phosphate.

[0076] Specific examples of fatty acid sulfates include castor oil fatty acid sulfate, sesame oil fatty acid sulfate, tall oil fatty acid sulfate, soybean oil fatty acid sulfate, rapeseed oil fatty acid sulfate, palm oil fatty acid sulfate, lard fatty acid sulfate, tallow fatty acid sulfate, and whale oil fatty acid sulfate.

[0077] Specific examples of the sulfate esters of fats and oils include sulfate esters of castor oil, sesame oil, tall oil, soybean oil, rapeseed oil, palm oil, lard, tallow, and whale oil.

[0078] Examples of salts include ammonium salts, amine salts, and metal salts. Examples of metal salts include alkali metal salts and alkaline earth metal salts. Specific examples of alkali metals constituting alkali metal salts include sodium, potassium, and lithium. Examples of alkaline earth metals constituting alkaline earth metal salts include metals corresponding to Group 2 elements, such as calcium, magnesium, beryllium, strontium, and barium.

[0079] The amine constituting the amine salt may be any of a primary amine, a secondary amine, and a tertiary amine. Specific examples of amines constituting amine salts include: (1) aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, NN-diisopropylethylamine, butylamine, dibutylamine, 2-methylbutylamine, tributylamine, octylamine, and dimethyllaurylamine; (2) aromatic amines or heterocyclic amines such as aniline, N-methylbenzylamine, pyridine, morpholine, piperazine, and derivatives thereof; (3) alkanolamines such as monoethanolamine, N-methylethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, dibutylethanolamine, butyldiethanolamine, octyldiethanolamine, and lauryldiethanolamine; (4) arylamines such as N-methylbenzylamine; (5) polyoxyalkylene alkylaminoethers such as polyoxyethylene laurylaminoether and polyoxyethylene stearylaminoether; (6) ammonia; and the like.

[0080] It should be noted that, for example, among the above-mentioned anionic components, metal salts of fatty acids and the like constitute anionic surfactants. Therefore, anionic surfactants can be used as the anionic component.

[0081] Examples of the cationic component include cationic surfactants and organic amines.

[0082] Specific examples of the cationic surfactant include lauryltrimethylammonium chloride, hexadecyltrimethylammonium chloride, stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, didecyldimethylammonium chloride, and 1,2-dimethylimidazole.

[0083] Specific examples of organic amines include: (1) aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, NN-diisopropylethylamine, butylamine, dibutylamine, 2-methylbutylamine, tributylamine, octylamine, laurylamine, and dimethyllaurylamine; (2) aromatic amines or heterocyclic amines such as aniline, N-methylbenzylamine, pyridine, morpholine, piperazine, and derivatives thereof; (3) alkanolamines such as monoethanolamine, N-methylethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, dibutylethanolamine, butyldiethanolamine, octyldiethanolamine, and lauryldiethanolamine; (4) arylamines such as 3-aminopropylene; (5) polyoxyalkylene alkylaminoethers such as N,N-bis(polyoxyethylene)dodecylamine (n=10), polyoxyethylene laurylaminoether, and polyoxyethylene stearylaminoether; and the like.

[0084] Among these ionic components (D), one type of ionic component may be used alone, or two or more types of ionic components may be used in appropriate combination.

[0085] The lower limit of the content of the ionic component (D) in the treatment agent can be appropriately set, preferably 0.05% by mass or more, more preferably 0.1% by mass or more. When the content is 0.05% by mass or more, the bundling of the flame-resistant fibers after the flame-resistant treatment of the carbon fiber precursor to which the treatment agent is applied can be further improved. The upper limit of the content of the ionic component (D) can be appropriately set, preferably 15% by mass or less, more preferably 10% by mass or less. When the content is 15% by mass or less, the stability of the treatment agent can be improved. It should be noted that a range formed by arbitrarily combining the above upper and lower limits can also be set.

[0086] When the total content of the smoothing agent (A), the (poly)oxyalkylene derivative (B), the condensed hydroxy fatty acid (C), and the ionic component (D) in the treatment agent is 100% by mass, it is preferred that the smoothing agent (A) be contained at a ratio of 9.9% to 89.9% by mass, the (poly)oxyalkylene derivative (B) be contained at a ratio of 9.9% to 89.9% by mass, the condensed hydroxy fatty acid (C) be contained at a ratio of 0.1% to 50% by mass, and the ionic component be contained at a ratio of 0.1% to 10% by mass. By limiting the content to this range, the effects of the present invention can be further enhanced.

[0087] According to the processing agent of the above-mentioned first embodiment, the following effects can be obtained.

[0088] (1-1) The treatment agent of the first embodiment contains a smoothing agent (A) comprising an ester compound (A1) of glycerol and a fatty acid containing a fatty acid (X) having 16 or more and 24 or less carbon atoms, and a (poly)oxyalkylene derivative (B). Furthermore, the composition ratio of the fatty acid (X) calculated from the above formula is 50% by mass or more. Thus, burrs on the flame-resistant fibers after the carbon fiber precursor to which the treatment agent has been applied is flame-resistant can be reduced. Furthermore, the bundling properties of the flame-resistant fibers can be improved. Furthermore, by improving the stability of the treatment agent, various functions of the treatment agent can be enhanced.

[0089] (1-2) The treatment agent of the first embodiment does not contain silicone oil as a lubricant as an essential component. Silicone oil can contaminate the firing furnace during use. Therefore, if silicone oil is not contained in the treatment agent, contamination of the firing furnace can be reduced. Furthermore, even without the addition of silicone oil as a lubricant, the aforementioned burrs can be reduced and bundling properties can be improved.

[0090] <Second embodiment>

[0091] Next, a second embodiment of the carbon fiber precursor of the present invention will be described. The carbon fiber precursor of this embodiment has the treatment agent of the first embodiment attached thereto.

[0092] The carbon fiber precursor is preferably a synthetic fiber that becomes a carbon fiber by undergoing a carbonization treatment process described later. The fiber raw material constituting the carbon fiber precursor is not particularly limited, and examples thereof include: (1) polyester fibers such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid; (2) polyamide fibers such as nylon 6 and nylon 66; (3) polyacrylic acid fibers such as polyacrylic acid and modified acrylic acid; (4) polyolefin fibers such as polyethylene and polypropylene; (5) cellulose fibers; (6) lignin fibers; (7) phenol resins; (8) asphalt; and the like. In addition, as polyacrylic acid fibers, it is preferable to be composed of fibers having polyacrylonitrile (which is obtained by copolymerizing at least 90 mol% of acrylonitrile and 10 mol% or less of a flame retardant promoting component) as the main component. As the flame retardant promoting component, for example, a vinyl group-containing compound copolymerizable with acrylonitrile can be appropriately used.

[0093] There is no particular restriction on the proportion in which the treatment agent of the first embodiment is attached to the carbon fiber precursor. It is preferred that the treatment agent (excluding solvent) be attached in an amount of 0.1% by mass or more and 2% by mass or less relative to the carbon fiber precursor, and more preferably be attached in an amount of 0.3% by mass or more and 1.2% by mass or less.

[0094] As a method for attaching the treatment agent to the carbon fiber precursor, for example, the following method can be applied: using a composition containing the treatment agent of the first embodiment and a solvent, or in the form of a diluted liquid further diluted with a solvent, attaching it by a known method, such as an immersion method, a spray method, a roller method, a guided oiling method using a metering pump, etc.

[0095] Next, a method for producing carbon fibers using the carbon fiber precursor of this embodiment will be described.

[0096] The method for producing carbon fibers preferably includes steps 1 to 3 described below.

[0097] Step 1: Spinning step: a raw material as a carbon fiber precursor is spun, and the treatment agent of the first embodiment is attached thereto.

[0098] Step 2: Flame-retardant treatment step of converting the carbon fiber precursor obtained in step 1 into flame-retardant fibers in an oxidizing atmosphere preferably at 200°C to 300°C, more preferably at 230°C to 270°C.

[0099] Step 3: Carbonization treatment step of carbonizing the flame-resistant fiber obtained in the above step 2 in an inert atmosphere preferably at 300° C. to 2000° C., more preferably at 300° C. to 1300° C.

[0100] It should be noted that the above-mentioned steps 2 and 3 constitute a firing step.

[0101] The treatment agent can be applied to the raw fiber of the carbon fiber precursor at any stage of the spinning process, but is preferably applied once before the stretching process. Alternatively, it can be applied again at any stage after the stretching process. For example, it can be applied immediately after the stretching process, during the winding process, or immediately before the flame retardant treatment process.

[0102] The oxidizing atmosphere in the flame retardant treatment step is not particularly limited, and for example, an air atmosphere can be used.

[0103] The inert atmosphere in the carbonization treatment step is not particularly limited, and for example, a nitrogen atmosphere, an argon atmosphere, a vacuum atmosphere, etc. can be used.

[0104] According to the carbon fiber precursor of the second embodiment described above, the following effects can be obtained.

[0105] (2-1) The carbon fiber precursor of the second embodiment has the treatment agent of the first embodiment attached thereto. Therefore, burrs on the flame-resistant fibers after the carbon fiber precursor has been flame-resistant treated can be reduced. This can improve yarn quality. Furthermore, the bundling properties of the flame-resistant fibers can be improved. This can reduce the amount of winding around the rollers during the firing process, thereby improving manufacturing efficiency.

[0106] The above embodiment can be implemented with the following modifications: The above embodiment and the following modifications can be implemented in combination with each other within the scope of no technical contradiction.

[0107] In the treatment agent of the present embodiment, only one of the condensed hydroxy fatty acid (C) and the ionic component (D) may be mixed, or both of them may be mixed.

[0108] The aforementioned treatment agent, composition containing the treatment agent, and diluent may contain commonly used ingredients such as stabilizers or charge control agents for maintaining quality, oily components other than those listed above, surfactants other than those listed above, antistatic agents, thickeners, antioxidants, ultraviolet absorbers, and defoaming agents, within a range that does not impair the effects of the present invention. To effectively demonstrate the effects of the present invention, the content of ingredients other than the solvent in the treatment agent is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0109] Example

[0110] In order to more specifically illustrate the configuration and effects of the present invention, examples are given below, but the present invention is not limited to these examples. It should be noted that in the following examples and comparative examples, parts refer to parts by mass, and % refers to mass %.

[0111] Test group 1 (treatment agent and dilution preparation)

[0112] (Example 1)

[0113] 60 parts (%) of castor oil (A-1) and 20 parts (%) of sunflower oil (A-6) as a smoothing agent (A), 14 parts (%) of ω-hydroxy(polyoxyethylene) (n=7) castor oil (B-1) as a (poly)oxyalkylene derivative (B), 5 parts (%) of condensed 12-hydroxystearic acid hexamer (C-1) as a condensed hydroxy fatty acid (C), and 1 part (%) of sodium dodecylbenzenesulfonate (D-1) as an ionic component (D) were added to a beaker and thoroughly mixed to prepare the treatment agent of Example 1. Subsequently, while continuing to stir, ion-exchanged water was slowly added to a solids concentration of 25%, thereby preparing a treatment agent-containing composition containing 25% of the treatment agent of Example 1.

[0114] (Examples 2 to 19, Comparative Examples 1 to 7)

[0115] The treatment agents of Examples 2 to 19 and Comparative Examples 1 to 7 were prepared by the same method as in Example 1 using the components shown in Table 1.

[0116] The type and content of the smoothing agent (A), the type and content of the (poly)oxyalkylene derivative (B), the type and content of the condensed hydroxy fatty acid (C), and the type and content of the ionic component (D) in the treatment agent of each example are shown in the "Smoothing Agent (A)" column, the "(Poly)oxyalkylene Derivative (B)" column, the "Condensed Hydroxy Fatty Acid (C)" column, and the "Ionic Component (D)" column of Table 1. The ester compounds (A1) contained in the smoothing agents (A-7) to (A-9) were synthesized by the method shown below.

[0117] Test Group 2 (Synthesis of Smoothing Agents (A-7) to (A-9))

[0118] (Smoothing Agent (A-7))

[0119] A 2L four-necked flask equipped with a thermometer, vacuum pump, nitrogen inlet tube, stirrer, and cooling trap was charged with 92.1g of glycerol, 160.3g of lauric acid, and 617.1g of ricinoleic acid. Next, 3.3g of p-toluenesulfonic acid monohydrate and 1.1g of a 50% aqueous solution of phosphinic acid were added as catalysts. The four-necked flask was heated in an oil bath and reacted at 130°C under a nitrogen stream for 2 hours, followed by 12 hours at 150°C and 2kPa. The water generated by the reaction was distilled out of the system. The acid value after the reaction was 3.5mgKOH / g. After the reaction was completed, the reaction solution was cooled to 60°C. A 5% aqueous sodium hydroxide solution was added to the reaction solution in an amount sufficient to completely neutralize the residual fatty acids and the acid catalyst, and the mixture was stirred for 30 minutes. Ion-exchanged water was added to the stirring reaction solution to 100% of the reaction solution volume, and the mixture was stirred for a further 30 minutes. After stopping stirring, the mixture was allowed to stand for 1 hour, and the aqueous layer that separated to the bottom was removed. Next, the following procedure was repeated twice: 100% ion-exchanged water was added relative to the reaction solution, stirred at 60°C for 10 minutes, allowed to stand for 2 hours, and the separated aqueous layer was removed. Dehydration was then performed at 100°C and 2 kPa. 2% activated clay was added to the resulting crude product as an adsorbent, stirred at 80°C and 5 kPa for 1 hour, and the adsorbent was removed to obtain an ester compound. This ester compound was used as a smoothing agent (A-7). The fatty acid ratios constituting this ester compound were 27% lauric acid and 73% ricinoleic acid.

[0120] In addition, the ratio of the fatty acid constituting the obtained ester compound was measured by the following method.

[0121] <Creation of Calibration Curve>

[0122] To convert the fatty acid ratios of each sample to mass, samples were prepared by adding various fatty acids and margaric acid as a standard substance in arbitrary amounts. Fatty acid methyl esters were prepared using the methyl esterification method (boron trifluoride methanol method) outlined in the "Standard Test Methods for Oil and Fats Analysis" compiled by the Japan Oil Chemists' Society. The prepared samples were analyzed by gas chromatography under the following conditions.

[0123] <Gas Chromatography Analysis Conditions>

[0124] Device: GC-2010Plus manufactured by Shimadzu Corporation

[0125] Column: DB-1 30 m × 0.25 mm × 0.25 μm (manufactured by Agilent J&W)

[0126] Carrier gas: nitrogen 1mL / min

[0127] Ejector: Split (1:50), T = 300 ° C

[0128] Detector: FID, T=300℃

[0129] Oven temperature: maintain at 50°C for 10 minutes, then increase the temperature at 5°C / min, and then maintain at 280°C for 10 minutes

[0130] Calibration curves of the concentrations and peak area ratios of various fatty acid methyl esters were prepared based on the gas chromatography results.

[0131] <Determination of Fatty Acid Ratio of Smoothing Agent>

[0132] Add 1 g of a smoothing agent and 100 ml of a 2N sodium hydroxide-methanol solution to a flask, heat in a 60°C water bath, and stir for 30 minutes to perform saponification. After cooling the saponified sample to room temperature, place it in a separatory funnel. Repeat the following procedure twice: add 100% ion-exchanged water relative to the liquid volume, let it stand for 2 hours, and then remove the separated water layer. Then, dehydrate at 100°C and 2 kPa to obtain fatty acids. Prepare a sample by adding an arbitrary amount of heptadecanoic acid as a standard substance to the obtained fatty acids. For the prepared samples, prepare fatty acid methyl ester samples according to the methylation method (boron trifluoride methanol method) in the "Standard Oil and Fats Analysis Test Method" compiled by the Japan Oil Chemists' Society. Analyze the prepared fatty acid methyl ester samples by gas chromatography under the above conditions. Based on the obtained gas chromatographic results, determine the peak area ratio of the standard substance to each fatty acid methyl ester, and calculate the composition ratio of each fatty acid.

[0133] (Smoothing agent (A-8))

[0134] Smoothing agent (A-8) was synthesized using the same process as for smoothing agent (A-7), except that 92.1 parts of glycerol, 144.2 parts of caprylic acid, and 512.8 parts of palmitic acid were used as raw materials. The ratios of fatty acids constituting the ester compound contained in smoothing agent (A-8) are shown in Table 2 below.

[0135] (Smoothing Agent (A-9))

[0136] Smoothing agent (A-9) was synthesized using the same process as for smoothing agent (A-7), except that 92.1 parts of glycerin, 300.5 parts of lauric acid, and 423.8 parts of oleic acid were used as raw materials. The ratios of fatty acids constituting the ester compound contained in smoothing agent (A-9) are shown in Table 2 below.

[0137] [Table 1]

[0138]

[0139] The details of the smoothing agent (A), the (poly)oxyalkylene derivative (B), the condensed hydroxy fatty acid (C), and the ionic component (D) described in Table 1 are as follows.

[0140] (Smoothing agent (A))

[0141] A-1: Castor Oil

[0142] A-2: Rapeseed oil

[0143] A-3: Sesame oil

[0144] A-4: Palm oil

[0145] A-5: Flaxseed oil

[0146] A-6: Sunflower oil

[0147] A-7: Ester compound of glycerol, lauric acid, and ricinoleic acid (the fatty acid composition ratio is 27% lauric acid, 73% ricinoleic acid)

[0148] A-8: Ester compound of glycerol, caprylic acid, and palmitic acid (the fatty acid composition ratio is caprylic acid 33%, palmitic acid 67%)

[0149] A-9: Ester compound of glycerol, lauric acid, and oleic acid (the fatty acid composition ratio is 50% lauric acid and 50% oleic acid)

[0150] rA-1: Coconut oil

[0151] rA-2: Palm kernel oil

[0152] The composition ratio (%) of the fatty acid in the ester compound (A1) contained in each of the smoothing agents (A) A-1 to A-9, rA-1, and rA-2 is shown in the "Fatty Acid" column of the following Table 2. Furthermore, the ratio (%) of the fatty acid (X) having 16 or more and 24 or less carbon atoms, which constitutes the ester compound (A1), relative to the total mass of the fatty acids, is shown in the "Composition ratio of fatty acid (X)" column of Table 2.

[0153] [Table 2]

[0154]

[0155] ((Poly)oxyalkylene derivative (B))

[0156] B-1: ω-Hydroxy (polyoxyethylene) (n=7) castor oil

[0157] B-2: ω-Hydroxy (polyoxyethylene) (n=20) hydrogenated castor oil

[0158] B-3: Hydroxy(polyoxypropylene polyoxyethylene) (m=13, n=10) castor oil

[0159] B-4: Hydroxy(polyoxypropylene polyoxyethylene) (m=12, n=12) hydrogenated castor oil

[0160] B-5: Oil and fat ethylene oxide adduct prepared by adding 200 mol of ethylene oxide to 1 mol of castor oil

[0161] B-6: α-dodecyl-ω-hydroxy(polyoxyethylene) (n=7)

[0162] B-7: A polyoxyalkylene block copolymer having a number average molecular weight of 5000 obtained by block addition polymerization of ethylene oxide and propylene oxide to ethylene glycol, wherein the polyoxyalkylene block copolymer is composed of ethylene oxide units / propylene oxide units in a ratio of 30 / 70 (molar ratio)

[0163] B-8: A polyoxyalkylene block copolymer having a number average molecular weight of 10,000 obtained by block addition polymerization of ethylene oxide and propylene oxide to ethylene glycol, wherein the polyoxyalkylene block copolymer is composed of an ethylene oxide unit / propylene oxide unit at a ratio of 70 / 30 (molar ratio)

[0164] B-9: Polyoxyethylene glycol octadecenyl ether having 20 repeating ethylene oxide units

[0165] (Condensed hydroxy fatty acid (C))

[0166] C-1: Condensed 12-hydroxystearic acid hexamer

[0167] C-2: A mixture of condensed castor oil fatty acid tetramers and pentamers

[0168] C-3: Condensed castor oil fatty acid hexamer

[0169] C-4: Condensed castor oil fatty acid dimer

[0170] rc-1: Polyoxyalkylene-modified fatty amide prepared by addition polymerization of ethylene oxide at a ratio of 7 mol per 1 mol of distearyl amide of diethylenetriamine

[0171] rc-2: castor oil fatty acid

[0172] rc-3: 12-hydroxystearic acid

[0173] rc-4: Isostearic acid

[0174] (Ionic component (D))

[0175] D-1: Sodium dodecylbenzenesulfonate

[0176] D-2: Potassium 2-ethylhexyl phosphate

[0177] D-3: Potassium acetate

[0178] D-4: N,N-bis(polyoxyethylene) (n=10) dodecylamine acetate

[0179] D-5: polyoxyethylene glycol (number of repetitions of ethylene oxide units: 16) monohexadecyle ether phosphate potassium salt, an organic phosphate salt composed of monophosphate salt / diphosphate salt = 1 / 1 (molar ratio)

[0180] Test Group 3 (Manufacturing of Carbon Fiber Precursor and Carbon Fiber)

[0181] The diluted solution containing the treatment agent prepared in Test Group 1 was used to produce a carbon fiber precursor and carbon fibers.

[0182] First, in step 1, an acrylic resin was wet-spun. Specifically, a copolymer with an intrinsic viscosity of 1.80 composed of 95% acrylonitrile, 3.5% methyl acrylate, and 1.5% methacrylic acid was dissolved in dimethylacetamide (DMAC) to prepare a spinning solution with a polymer concentration of 21.0% and a viscosity of 500 poise at 60°C. The spinning solution was discharged from a coagulation bath of a 70% aqueous solution of DMAC maintained at a spinning bath temperature of 35°C using a spinning nozzle with an inner diameter of 0.075 mm and 12,000 holes at a draft ratio of 0.8.

[0183] The coagulated filaments were desolventized in a water washing tank and simultaneously stretched to 5 times to produce a water-swollen acrylic fiber strand (carbon fiber precursor). The treatment agent-containing composition prepared in Test Group 1 was further diluted with ion-exchanged water to prepare a 4% treatment agent dilution. This acrylic fiber strand was then oiled by dipping the 4% dilution to a solids content of 1% (without solvent). The acrylic fiber strands were then dried and densified using heated rollers at 130°C, and further stretched to 1.7 times between heated rollers at 170°C. The carbon fiber precursor was then wound onto a yarn tube using a winding device.

[0184] Next, as step 2, the wound carbon fiber precursor is unwound and subjected to flame retardant treatment for 1 hour in an air atmosphere using a flame retardant furnace with a temperature gradient of 230 to 270°C. The yarn is then wound onto a yarn tube via a conveying roller to obtain flame retardant yarn (flame retardant fiber).

[0185] Next, in step 3, the wound flame-resistant yarn is unwound and fired in a carbonization furnace with a temperature gradient of 300 to 1300° C. under a nitrogen atmosphere to convert it into carbon fibers, which are then wound around a yarn tube to obtain carbon fibers.

[0186] Test Group 4 (Evaluation)

[0187] The stability of the treatment agent, the burrs of the flame-resistant fibers, and the bundling properties of the respective examples and comparative examples were evaluated. The procedures for each test are as follows.

[0188] (glitch)

[0189] The flame-resistant fibers were measured using a burr counter installed immediately before the winding device. The number of burrs per hour was evaluated according to the following criteria. The test results are shown in the "Burr" column of Table 1.

[0190] Burr evaluation criteria

[0191] ◎◎ (Excellent): The number of burrs is 0 or more and 5 or less

[0192] ◎ (Good): The number of burrs is 6 or more and 10 or less

[0193] ○ (Pass): The number of burrs is 11 or more and 20 or less

[0194] × (Unqualified): The number of burrs is 21 or more

[0195] (Clustering)

[0196] The bundled state of the flame-resistant fibers before winding was visually observed, and the bundling properties were evaluated according to the following criteria. The test results are shown in the "Bundling Properties" column of Table 1.

[0197] Cluster evaluation criteria

[0198] ◎◎ (Excellent): Bunching occurs and the tow width is constant

[0199] ◎ (Good): Bunching occurs roughly, but the bundle width is sometimes not constant.

[0200] ○ (Acceptable): Bunching occurs roughly, but the bundle width is not constant.

[0201] × (unacceptable): There are spaces in the fiber bundles, and no bundling occurs.

[0202] (stability)

[0203] After preparing the treatment agent, 100 g was added to a 100 ml vertical sedimentation tube. After standing at 25°C for 72 hours, the appearance of the treatment agent was visually observed. The concentration difference between the upper and lower layers of the treatment agent was measured, and stability was evaluated according to the following criteria. The concentration difference was determined by taking a certain amount from the portion near the upper surface of the treatment agent and the portion near the bottom of the sedimentation tube, drying them at 105°C for 2 hours, and calculating the resulting solid content. The test results are shown in the "Stability" column in Table 1.

[0204] Stability evaluation criteria

[0205] ◎◎◎ (Excellent): No change in appearance is observed even when left to stand

[0206] ◎◎ (Excellent): Separation was observed, and the concentration difference between the upper and lower layers was 5% or less, but the original state was restored by stirring.

[0207] ◎ (Good): Separation was observed, and the concentration difference between the upper and lower layers was greater than 5% and less than 10%, but the original state was restored by stirring.

[0208] ○ (Pass): Separation is observed, and the concentration difference between the upper and lower layers is greater than 10%, but the original state is restored by stirring.

[0209] × (unacceptable): Separation was observed and the original state was not restored even after stirring.

[0210] The results in Table 1 indicate that the present invention can improve the burr reduction effect and bundling properties of flame-resistant fibers. Furthermore, the stability of the treatment agent can be improved.

Claims

1. A treating agent for carbon fiber precursor, characterized in that The treatment agent for a carbon fiber precursor contains a smoothing agent (A), a (poly)oxyalkylene derivative (B), and a condensed hydroxy fatty acid (C), wherein the smoothing agent (A) comprises an ester compound (A1) of glycerol and a fatty acid comprising the following fatty acid (X), and the condensed hydroxy fatty acid (C) is formed by a dehydration condensation reaction of a hydroxy fatty acid, wherein the hydroxy fatty acid is at least one selected from the group consisting of 12-hydroxy-9-octadecenoic acid (ricinoleic acid), 12-hydroxystearic acid, 16-hydroxyhexadecanoic acid (cadinic acid), 18-hydroxyoctadecanoic acid, 9-hydroxystearic acid, 10-hydroxystearic acid, 12-hydroxydodecanoic acid (sabinic acid), 9,10-dihydroxyoctadecanoic acid, castor oil fatty acid, and hydrogenated castor oil fatty acid, and the degree of condensation of the condensed hydroxy fatty acid is not less than a dimer and not more than a hexamer. The composition ratio of the fatty acid (X) obtained from the following mathematical formula 1 is 50% by mass or more, [Number 1] Fatty acid (X): a fatty acid having 16 to 24 carbon atoms.

2. The carbon fiber precursor treating agent according to claim 1, wherein The constituent ratio of the fatty acid (X) obtained from the above-mentioned Mathematical Formula 1 is 70% by mass or more.

3. The carbon fiber precursor treating agent according to claim 1, wherein The (poly)oxyalkylene derivative (B) includes a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to an ester compound of a monovalent or higher and trivalent alcohol and a monovalent fatty acid having 16 to 24 carbon atoms.

4. The carbon fiber precursor treating agent according to claim 1, wherein When the total content of the smoothing agent (A) and the (poly)oxyalkylene derivative (B) is 100 mass%, the smoothing agent (A) is contained in a ratio of 10 mass% to 90 mass%, and the (poly)oxyalkylene derivative (B) is contained in a ratio of 10 mass% to 90 mass%.

5. The carbon fiber precursor treating agent according to claim 1, wherein When the total content ratio of the smoothing agent (A), the (poly)oxyalkylene derivative (B), and the condensed hydroxy fatty acid (C) is set to 100 mass%, the smoothing agent (A) is contained in a ratio of 9.9 mass% to 89.9 mass%, the (poly)oxyalkylene derivative (B) is contained in a ratio of 10 mass% to 90 mass%, and the condensed hydroxy fatty acid (C) is contained in a ratio of 0.1 mass% to 50 mass%. The treating agent for carbon fiber precursor according to claim 1 , further comprising an ionic component (D).

7. The carbon fiber precursor treating agent according to claim 6, wherein When the total content ratio of the smoothing agent (A), the (poly)oxyalkylene derivative (B), the condensed hydroxy fatty acid (C), and the ionic component (D) is 100 mass%, the smoothing agent (A) is contained in a ratio of 9.9 mass% to 89.9 mass%, the (poly)oxyalkylene derivative (B) is contained in a ratio of 9.9 mass% to 89.9 mass%, the condensed hydroxy fatty acid (C) is contained in a ratio of 0.1 mass% to 50 mass%, and the ionic component is contained in a ratio of 0.1 mass% to 10 mass%.

8. A carbon fiber precursor, characterized in that The carbon fiber precursor treatment agent according to any one of claims 1 to 7 is adhered thereto.

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