Agent for treating carbon fiber precursor and use thereof

Abstract

The purpose of the present invention is to provide an agent for treating a carbon fiber precursor, the agent being capable of suppressing degradation of the carbon fiber precursor even when the carbon fiber precursor produced by applying the agent for treating a carbon fiber precursor is stored for a long period of time, and being capable of obtaining carbon fibers having excellent physical properties even when the carbon fiber precursor stored for a long period of time is used.　This agent for treating a carbon fiber precursor contains (A) a silicone having an amino group, (B) a silicone having an aryl group, and (C1) an aliphatic (poly)oxyalkylene derivative. The weight ratio (B / A) of the silicone (B) having an aryl group to the silicone (A) having an amino group is preferably 1 or less.

Description

Treatment agent for carbon fiber precursor and its use

[0001] The present invention relates to a treatment agent for carbon fiber precursors and uses thereof. More specifically, the present invention relates to a treatment agent used in producing carbon fiber precursors, a carbon fiber precursor (hereinafter sometimes referred to as a precursor) using the treatment agent, and a method for producing carbon fibers using the treatment agent.

[0002] Taking advantage of their excellent mechanical properties, carbon fibers are widely used as reinforcing fibers for composite materials with plastics known as matrix resins in aerospace, sports, general industrial, and other applications. A common method for producing carbon fibers involves first producing a carbon fiber precursor (this production process is sometimes referred to as the "spinning process"). This carbon fiber precursor is converted into a flame-resistant fiber in an oxidizing atmosphere at 200 to 300°C (this process is sometimes referred to as the "flame-resistant treatment process" below), followed by carbonization in an inert atmosphere at 300 to 2000°C (this process is sometimes referred to as the "carbonization treatment process" below). (The flame-resistant treatment process and carbonization treatment process are collectively referred to as the "sintering process" below.) During this firing process, fusion between single fibers occurs, which can easily cause problems such as fluffing and thread breakage, hindering productivity improvement.

[0003] In order to prevent the fusing of single fibers together during the baking process, a silicone-based treatment agent is applied to the carbon fiber precursor during production, and many techniques have been proposed for applying the treatment agent in the form of an aqueous emulsion in order to apply it uniformly (see Patent Documents 1 and 2).

[0004] Japanese Patent Publication No. 2012-46855 Japanese Patent Publication No. 2016-17231

[0005] However, when a carbon fiber precursor produced by applying such a treatment agent is stored for a long period of time, there is a problem that the carbon fiber precursor deteriorates over time. Therefore, when a carbon fiber is produced by calcining a carbon fiber precursor that has been stored for a long period of time, there are problems such as the generation of fluff in the calcination process and a decrease in the strength of the carbon fiber after calcination. In view of this conventional technical background, an object of the present invention is to provide a treatment agent for carbon fiber precursors that can suppress the deterioration of a carbon fiber precursor when a carbon fiber precursor produced by applying a treatment agent is stored for a long period of time, a carbon fiber precursor using the treatment agent, and a method for producing carbon fiber using the treatment agent.

[0006] As a result of intensive research to solve the above problems, the present inventors have found that a treatment agent for carbon fiber precursors containing a silicone (A) having an amino group, a silicone (B) having an aryl group, and an aliphatic (poly)oxyalkylene derivative (C1) can suppress deterioration of the carbon fiber precursor when the carbon fiber precursor produced by applying the treatment agent for carbon fiber precursors is stored for a long period of time, and have arrived at the present invention.

[0007] That is, the treatment agent for carbon fiber precursors of the present invention includes the following embodiments. <1> A treatment agent for carbon fiber precursors, comprising an amino group-containing silicone (A), an aryl group-containing silicone (B), and an aliphatic (poly)oxyalkylene derivative (C1). <2> The treatment agent for carbon fiber precursors according to <1>, in which the weight ratio (B / A) of the aryl group-containing silicone (B) to the amino group-containing silicone (A) is 1 or less. <3> The treatment agent for carbon fiber precursors according to <1> or <2>, in which the weight ratio (B / C1) of the aryl group-containing silicone (B) to the aliphatic (poly)oxyalkylene derivative (C1) is 9 or less. <4> The treatment agent for carbon fiber precursors according to any one of <1> to <3>, comprising an aromatic (poly)oxyalkylene derivative (C2). <5> The treatment agent for carbon fiber precursors according to <4>, in which the derivative (C2) includes a compound having a bisphenol skeleton. <6> The treatment agent for carbon fiber precursors according to any one of <1> to <5>, wherein the proportion of the silicone (B) having an aryl group in the non-volatile content of the treatment agent is 60% by weight or less. <7> The treatment agent for carbon fiber precursors according to any one of <1> to <6>, wherein the silicone (B) having an aryl group includes a silicone (B1) having a phenyl group. <8> The treatment agent for carbon fiber precursors according to any one of <1> to <7>, wherein the silicone (B) having an aryl group includes at least one selected from methylphenylsilicones and diphenylsilicones. <9> The treatment agent for carbon fiber precursors according to <8>, wherein the molar ratio of phenyl groups to methyl groups (phenyl groups:methyl groups) in the methylphenylsilicones and the diphenylsilicones is 1:99 to 90:10. <10> The treatment agent for carbon fiber precursors according to any one of <1> to <9>, wherein the proportion of the silicone having a polyether group in the non-volatile content of the treatment agent is 0 to 10% by weight. <11> The treating agent for carbon fiber precursors according to any one of <1> to <10>, which has a pH of 4 to 8 when diluted to a non-volatile content of 1.0 wt %. <12> A carbon fiber precursor obtained by adhering the treating agent for carbon fiber precursors according to any one of <1> to <11> to a raw material carbon fiber precursor for the carbon fiber precursor.<13> A method for producing a carbon fiber, comprising: a flame-resistant treatment step of converting the carbon fiber precursor according to <12> into a flame-resistant fiber; and a carbonization treatment step of further carbonizing the flame-resistant fiber.

[0008] The treating agent for carbon fiber precursors of the present invention can suppress deterioration of the carbon fiber precursor even when the carbon fiber precursor produced by applying the treating agent is stored for a long period of time, and carbon fibers with excellent physical properties can be obtained even when a carbon fiber precursor stored for a long period of time is used. The carbon fiber precursor and the method for producing carbon fiber of the present invention can obtain carbon fibers with excellent physical properties even when a carbon fiber precursor stored for a long period of time is used.

[0009] The components of the treating agent for carbon fiber precursors of the present invention (hereinafter sometimes simply referred to as the treating agent) will be described below. [Silicone (A) Having an Amino Group] The treating agent of the present invention contains a silicone (A) having an amino group. The silicone (A) having an amino group is not particularly limited as long as its main chain is an inorganic siloxane bond (—Si—O—Si—) and it has an organic group having an amino group on the side chain and / or terminal. Examples of the silicone (A) having an amino group include amino-modified silicones and amino polyether-modified silicones. In terms of achieving the effects of the present invention, it is more preferable to include an amino-modified silicone. Note that an amino polyether-modified silicone is a silicone having an amino group (including an organic group having an amino group) and a polyether group (including an organic group having a polyoxyalkylene group). Known amino-modified silicones and amino polyether-modified silicones can be used. One or more types of silicone (A) having an amino group may be used.

[0010] The amino group-containing silicone (A) has a kinematic viscosity at 25°C of 50 to 20,000 mm3 in order to achieve uniform adhesion to fibers, suppress the scattering of the treatment agent, and provide fiber bundling properties. ２ The upper limit of the kinematic viscosity is more preferably 15,000 mm ２ / s, more preferably 12000 mm ２ / s, particularly preferably 10,000 mm ２ On the other hand, the lower limit of the kinematic viscosity is more preferably 100 mm２ / s, more preferably 150 mm ２ / s, particularly preferably 200 mm ２ / s. For example, 100 to 15,000 mm ２ / s is more preferable, and 150 to 10,000 mm ２ / s is more preferred.

[0011] The amino group (including an organic group having an amino group) which is the modified group of the amino group-containing silicone (A) may be bonded to a side chain of the silicone main chain, or to an end, or may be bonded to both, but from the viewpoint of protecting the fibers in the flame-resistant treatment step, it is preferable that it be bonded to a side chain (having an amino group on the side chain). Furthermore, the amino group may be any of a monoamine type, a diamine type, or a polyamine type, and both may coexist in one molecule, but from the viewpoint of uniformly applying the treatment agent to the inside of the fiber bundle in the flame-resistant treatment step and forming a film with the treatment agent to protect the fibers, the monoamine type or diamine type is preferred, and the diamine type is more preferred.

[0012] The amino equivalent of the amino group-containing silicone (A) is preferably 300 to 10,000 g / mol from the viewpoint of preventing adhesion or fusion between fibers. The upper limit of the amino equivalent is more preferably 9,500 g / mol, even more preferably 9,000 g / mol, and particularly preferably 8,000 g / mol. Meanwhile, the lower limit of the amino equivalent is more preferably 500 g / mol, even more preferably 1,000 g / mol, and particularly preferably 1,500 g / mol. Furthermore, for example, 500 to 9,000 g / mol is more preferable, and 1,000 to 8,000 g / mol is even more preferable. Here, the amino equivalent refers to the mass of the siloxane skeleton per amino group or ammonium group. The unit of g / mol is a value converted to per mol of amino groups or ammonium groups. Therefore, a smaller amino equivalent value indicates a higher ratio of amino groups or ammonium groups in the molecule.

[0013] The amino group-containing silicone (A) may be a combination of multiple amino group-containing silicones with different amino equivalents and kinematic viscosities (25°C). When two or more types of amino group-containing silicones are used, the amino equivalent refers to the amino equivalent of the entire amino group-containing silicone (A) (mixture), and the kinematic viscosity at 25°C refers to the kinematic viscosity of the entire amino group-containing silicone (A) (mixture).

[0014] Examples of the silicone (A) having an amino group include compounds represented by the following general formula (1).

[0015] (In formula (1), R １ represents an alkyl group having 1 to 20 carbon atoms. ２ is a group represented by the following general formula (2): ３ is R １ , R ２ Or -OR ９ (R ９ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. a is 1≦a≦10000, and b is 0≦b≦1000. However, when b=0, R ３ At least one of the repeating units a and b is a group represented by the following general formula (2). The order of the repeating units bounded by a and b is not limited, and the bonding pattern may be alternating, block, or random.

[0016] In formula (1), R １ is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group. １ may be the same or different. ３ is R １ , R ２ Or -OR ９ and preferably R １ In addition, the plurality of R in formula (1) ９ may be the same or different. ９is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom or a methyl group. a is a number from 1 to 10,000, preferably 30 to 5,000, and more preferably 50 to 2,000. b is a number from 0 to 1,000, preferably 1 to 500, and more preferably 2 to 100.

[0017]

[0018] In formula (2), R ４ and R ６ are each independently an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms. ５ , R ７ and R ８ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and more preferably a hydrogen atom. c is a number from 0 to 6, preferably 0 to 3, and more preferably 0 to 1.

[0019] [Aryl Group-Containing Silicone (B)] The treatment agent of the present invention contains an aryl group-containing silicone (B). The aryl group-containing silicone (B) has a main chain formed of an inorganic siloxane bond (—Si—O—Si—) and has aryl groups on the side chains and / or terminals, and is not particularly limited as long as it is other than the amino group-containing silicone (A). The aryl group contained in the aryl group-containing silicone (B) is not particularly limited, but examples include a phenyl group, an aralkyl group, a naphthyl group, a tolyl group, and a xylyl group. In terms of achieving the effects of the present invention, it is preferable for the silicone (B) to contain one selected from a phenyl group and an aralkyl group, and it is more preferable for the silicone (B) to contain a phenyl group. One or more types of aryl group-containing silicone (B) may be used.

[0020] The kinetic viscosity of the aryl group-containing silicone (B) at 25°C is 10 to 20,000 mm3 in terms of uniform adhesion to fibers and prevention of scattering of the treatment agent. ２ The upper limit of the kinematic viscosity is preferably (1) 15,000 mm ２ / s, (2) 10000mm２ / s, (3) 8000mm ２ / s, (4) 1000mm ２ / s, (5) 495mm ２ / s, (6) 295mm ２ On the other hand, the lower limit of the kinematic viscosity is (1) 30 mm ２ / s, (2) 50mm ２ / s, (3) 55mm ２ / s, (4)70mm ２ / s, (4) 100mm ２ / s (the larger the number in parentheses, the more preferable it is). ２ / s is more preferable, and 50 to 1000 mm ２ / s is more preferable, and 55 to 495 mm ２ / s is particularly preferred, and 55 to 295 mm ２ / s is most preferred.

[0021] The aryl group, which is the modifying group of the aryl group-containing silicone (B), may be bonded to a side chain of the silicone main chain, or to an end, or may be bonded to both. However, from the viewpoint of protecting the fibers in the flame-resistant treatment step, it is preferable that the aryl group be bonded to a side chain (having an aryl group in the side chain).

[0022] From the viewpoint of emulsion stability, the silicone (B) having an aryl group preferably contains a silicone (B1) having a phenyl group, and more preferably contains methylphenylsilicone or diphenylsilicone, and diphenylsilicone is more preferred. The methylphenylsilicone is a silicone having a methylphenylsiloxane unit ((CH ３ ) (C ６ H ５ ) SiO ２／２ ) and dimethylsiloxane units ((CH ３ ) ２ SiO ２／２ ) and diphenylsilicones include silicones having a diphenylsiloxane unit ((C ６ H ５ ) ２ SiO ２／２ ) and dimethylsiloxane units ((CH３ ) ２ SiO ２／２ ) silicones having

[0023] The molar ratio of phenyl groups to methyl groups (phenyl groups:methyl groups) in the methylphenylsilicone and diphenylsilicone is not particularly limited, but from the viewpoint of emulsion stability, it is preferably from 1:99 to 90:10, more preferably from 1:99 to 70:30, even more preferably from 1:99 to 50:50, and particularly preferably from 1:99 to 30:70.

[0024] The aryl group-containing silicone (B) may be a combination of multiple aryl group-containing silicones with different kinematic viscosities (25°C). When two or more types of aryl group-containing silicones are used, the kinematic viscosity at 25°C refers to the kinematic viscosity of the entire aryl group-containing silicone (B) (mixture).

[0025] [Aliphatic (poly)oxyalkylene derivative (C1)] The treatment agent of the present invention contains an aliphatic (poly)oxyalkylene derivative (C1) (hereinafter, sometimes referred to as aliphatic derivative (C1)). There are no particular limitations on the aliphatic derivative (C1) as long as it is an aliphatic compound having a (poly)oxyalkylene group. Examples include aliphatic alcohol alkylene oxide adducts (C1-1) and aliphatic alkylene oxide adducts (C1-2) having an ester group, with the aliphatic alcohol alkylene oxide adduct (C1-1) being preferred in terms of emulsion stability. One or more types of aliphatic (poly)oxyalkylene derivatives (C1) may be used.

[0026] Examples of the aliphatic alcohol alkylene oxide adduct (C1-1) include alkylene oxide adducts of aliphatic alcohols that do not have an ester group. The aliphatic alcohol constituting the aliphatic alcohol alkylene oxide adduct (C1-1) is not particularly limited, but examples include aliphatic alcohols having 2 to 24 carbon atoms. The aliphatic alcohol may be saturated or unsaturated, linear or branched, and may be a monohydric alcohol or a dihydric or higher alcohol. From the viewpoint of emulsion stability, monohydric linear saturated aliphatic alcohols and monohydric branched saturated aliphatic alcohols are preferred. One or more types of aliphatic alcohol alkylene oxide adduct (C1-1) may be used. The upper limit of the carbon number of the aliphatic alcohol is preferably 20, more preferably 18, and even more preferably 16. On the other hand, the lower limit of the carbon number is more preferably 4, even more preferably 6, and particularly preferably 8. Furthermore, for example, 6 to 18 is preferred, and 8 to 16 is more preferred.

[0027] Examples of the aliphatic alcohol constituting the aliphatic alcohol alkylene oxide adduct (C1-1) include butyl alcohol, octyl alcohol, nonanol, lauryl alcohol, stearyl alcohol, cetyl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, isotetracosanyl alcohol, 12-eicosyl alcohol, vinyl alcohol, butenyl alcohol, hexadecenyl alcohol, oleyl alcohol, eicosenyl alcohol, linear secondary alcohols having 10 to 16 carbon atoms, glycerin, trimethylolpropane, sorbitol, ethylene glycol, propylene glycol, and butylene glycol. From the viewpoint of emulsion stability, lauryl alcohol, stearyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, and linear secondary alcohols having 10 to 16 carbon atoms are preferred, and linear secondary alcohols having 10 to 16 carbon atoms are more preferred.

[0028] The number of moles of alkylene oxide added in the aliphatic alcohol alkylene oxide adduct (C1-1) is preferably 2 to 50 moles. The upper limit of the number of moles added is more preferably 40 moles, even more preferably 30 moles, and particularly preferably 20 moles. On the other hand, the lower limit of the number of moles added is more preferably 3 moles, even more preferably 4 moles, and particularly preferably 5 moles. Also, for example, 3 to 40 moles is more preferable, and 5 to 20 moles is particularly preferable. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, more preferably ethylene oxide, and the alkylene oxide may be added in a random or block manner.

[0029] Specific examples of the aliphatic alcohol alkylene oxide adduct (C1-1) include polyoxyethylene hexyl ether, polyoxyethylene heptyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene tetradecyl ether, polyoxyethylene cetyl ether, polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, polyoxyethylene isostearyl ether, polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-oct ... Examples of the ethoxylates include polyoxyethylene 1-octylhexyl ether, polyoxyethylene 1-hexyloctyl ether, polyoxyethylene 1-pentylheptyl ether, polyoxyethylene 1-heptylpentyl ether, polyoxyethylene 1-hexylheptyl ether, polyoxyethylene 1-heptylhexyl ether, polyoxyethylene 1-pentylcaptyl ether, polyoxyethylene 1-captylpentyl ether, polyoxyethylene oleyl ether, linear secondary alcohol ethoxylates having 10 to 16 carbon atoms, and oxyethylene-oxypropylene block or random copolymers.

[0030] Examples of the aliphatic alkylene oxide adduct (C1-2) having an ester group include those (C1-2-1) having a structure in which an alkylene oxide is added to an aliphatic carboxylic acid, and those (C1-2-2) having a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol. One or more types of the aliphatic alkylene oxide adduct (C1-2) having an ester group may be used.

[0031] The aliphatic carboxylic acid constituting the aliphatic alkylene oxide adduct (C1-2) having an ester group is not particularly limited, and examples thereof include an aliphatic monocarboxylic acid having 4 to 24 carbon atoms and an aliphatic polycarboxylic acid having 4 to 24 carbon atoms. The aliphatic carboxylic acid may be saturated or unsaturated, and may be linear or branched.

[0032] Examples of the aliphatic monocarboxylic acid having 4 to 24 carbon atoms include pentanoic acid, hexanoic acid, octanoic acid, 2-ethylhexanoic acid, octylic acid, decanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, isotridecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid), isooctadecanoic acid (isostearic acid), hydroxyoctadecanoic acid, 12-hydroxyoctadecanoic acid (12-hydroxystearic acid), octadecenoic acid, hydroxyoctadecenoic acid, octadecadienoic acid, octadecatrienoic acid, docosanoic acid (behenic acid), tetracosanoic acid, hexacosanoic acid, octadocosanoic acid, octacosanoic acid, ricinoleic acid, oleic acid, isostearic acid, and isoarachic acid. From the viewpoint of emulsion stability, dodecanoic acid, oleic acid, and isostearic acid are preferred.

[0033] The number of moles of alkylene oxide added in the aliphatic alkylene oxide adduct (C1-2) having an ester group is preferably 2 to 50 moles. The upper limit of the number of moles added is more preferably 40 moles, even more preferably 30 moles, and particularly preferably 20 moles. On the other hand, the lower limit of the number of moles added is more preferably 3 moles, even more preferably 4 moles, and particularly preferably 5 moles. Also, for example, 3 to 40 moles is more preferable, and 5 to 20 moles is particularly preferable. The alkylene oxide preferably includes at least one selected from ethylene oxide and propylene oxide, more preferably ethylene oxide, and the alkylene oxide may be added randomly or in blocks.

[0034] Examples of the compound (C1-2-1) having a structure in which an alkylene oxide is added to an aliphatic carboxylic acid include the compounds in which an alkylene oxide is added to the above-mentioned aliphatic carboxylic acids, and from the viewpoint of emulsion stability, a compound having a structure in which 1 to 20 moles of ethylene oxide are added to a carboxylic acid having 8 to 18 carbon atoms is preferred.

[0035] The polyhydric alcohol constituting the compound (C1-2-2) having a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol is preferably a dihydric, bromide, or tetrahydric alcohol having 2 to 6 carbon atoms, and more preferably a dihydric, bromide, or trihydric alcohol having 2 to 6 carbon atoms. Specific examples of the polyhydric alcohol include dihydric alcohols such as propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, and 1,6-hexanediol; trihydric alcohols such as glycerin and trimethylolpropane; and tetrahydric or higher alcohols such as pentaerythritol, sorbitan, and sorbitol.

[0036] Examples of the compound (C1-2-2) having a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol include the compounds in which an alkylene oxide is added to the ester compound of an aliphatic carboxylic acid and a polyhydric alcohol listed above. In terms of emulsion stability, alkylene oxide adducts of glycerin fatty acid esters and alkylene oxide adducts of sorbitan fatty acid esters are preferred.

[0037] [Aromatic (Poly)oxyalkylene Derivative (C2)] The treatment agent of the present invention may contain an aromatic (poly)oxyalkylene derivative (C2) (hereinafter, sometimes referred to as aromatic derivative (C2)). The aromatic derivative (C2) is not particularly limited as long as it is an aromatic compound having a (poly)oxyalkylene group. Examples include alkylene oxide adducts (C2-1) of aromatic compounds having a hydroxyl group, and aromatic alkylene oxide adducts (C2-2) having an ester group. Of these, alkylene oxide adducts (C2-1) of aromatic compounds having a hydroxyl group are preferred in terms of improving sizing properties during flame retardation. Note that the alkylene oxide adducts (C2-1) of aromatic compounds having a hydroxyl group do not have an ester group. The aromatic derivative (C2) preferably contains a compound having a bisphenol skeleton in terms of high heat resistance and improving sizing properties during flame retardation.

[0038] The aromatic compound having a hydroxyl group that constitutes the alkylene oxide adduct (C2-1) of an aromatic compound having a hydroxyl group is not particularly limited, but examples include compounds having a bisphenol skeleton, (poly)styrenated phenol, and alkylphenols. From the viewpoint of improving sizing ability during flame retardation, compounds having a bisphenol skeleton are preferred, and compounds having a bisphenol A skeleton are more preferred. The number of moles of alkylene oxide added in the alkylene oxide adduct (C2-1) of an aromatic compound having a hydroxyl group is preferably 2 to 60 moles. The upper limit of the number of moles added is more preferably 40 moles, even more preferably 30 moles, and particularly preferably 20 moles. On the other hand, the lower limit of the number of moles added is more preferably 4 moles, even more preferably 6 moles, and particularly preferably 8 moles. Also, for example, 4 to 40 moles is more preferred, and 6 to 30 moles is particularly preferred. The alkylene oxide added to the aromatic compound having a hydroxyl group is preferably at least one selected from ethylene oxide and propylene oxide, more preferably including ethylene oxide, and even more preferably ethylene oxide.

[0039] The alkylene oxide adduct (C2-1) of an aromatic compound having a hydroxyl group is not limited as long as it is an alkylene oxide adduct of the above-mentioned aromatic compound having a hydroxyl group. However, alkylene oxide adducts of bisphenol A, alkylene oxide adducts of styrenated phenol, and alkylene oxide adducts of polystyrenated phenol are preferred, and alkylene oxide adducts of bisphenol A are more preferred.

[0040] Examples of the aromatic alkylene oxide adduct (C2-2) having an ester group include an ester (C2-2-1) of an alkylene oxide adduct of an aromatic compound having a hydroxyl group and a carboxylic acid. The alkylene oxide adduct of an aromatic compound having a hydroxyl group that constitutes the ester (C2-2-1) of an alkylene oxide adduct of an aromatic compound having a hydroxyl group and a carboxylic acid is not particularly limited, but the above-mentioned alkylene oxide adduct (C2-1) of an aromatic compound having a hydroxyl group is preferred. Examples of the carboxylic acid that constitutes the ester of an alkylene oxide adduct of an aromatic compound having a hydroxyl group and a carboxylic acid include aliphatic carboxylic acids and aromatic carboxylic acids, and aliphatic carboxylic acids are preferred in terms of improving sizing ability during flame retardation.

[0041] The aliphatic carboxylic acid is not particularly limited, but examples thereof include aliphatic monocarboxylic acids having 4 to 24 carbon atoms and aliphatic polycarboxylic acids having 4 to 24 carbon atoms. The aliphatic carboxylic acid may be saturated or unsaturated, and may be linear or branched. One or more types of aliphatic carboxylic acids may be used.

[0042] Examples of the aliphatic monocarboxylic acid having 4 to 24 carbon atoms include pentanoic acid, hexanoic acid, octanoic acid, 2-ethylhexanoic acid, octylic acid, decanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, isotridecanoic acid, hexadecanoic acid, octadecanoic acid (stearic acid), isooctadecanoic acid (isostearic acid), hydroxyoctadecanoic acid, 12-hydroxyoctadecanoic acid (12-hydroxystearic acid), octadecenoic acid, hydroxyoctadecenoic acid, octadecadienoic acid, octadecatrienoic acid, docosanoic acid (behenic acid), tetracosanoic acid, hexacosanoic acid, octadocosanoic acid, octacosanoic acid, ricinoleic acid, oleic acid, isostearic acid, and isoarachic acid. In terms of emulsion stability, decanoic acid, dodecanoic acid, tridecanoic acid, and oleic acid are preferred.

[0043] Examples of the aliphatic polycarboxylic acid having 4 to 24 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, itaconic acid, mesaconic acid, and citraconic acid, with succinic acid and adipic acid being preferred from the viewpoint of emulsion stability.

[0044] The aromatic carboxylic acid is not particularly limited, but examples thereof include aromatic polycarboxylic acids having 8 to 40 carbon atoms and aromatic monocarboxylic acids having 7 to 14 carbon atoms. Examples of aromatic polycarboxylic acids having 8 to 40 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, diphenyl ether dicarboxylic acid, naphthalenedicarboxylic acid, phenylmalonic acid, phenylsuccinic acid, β-phenylglutaric acid, α-phenyladipic acid, β-phenyladipic acid, biphenyl-2,2'- or 4,4'-dicarboxylic acid, naphthalenedicarboxylic acid, sodium 5-sulfoisophthalate, potassium 5-sulfoisophthalate, and derivatives of these dicarboxylic acids, as well as trimellitic acid, pyromellitic acid, and derivatives of these trivalent or higher carboxylic acids. Examples of aromatic monocarboxylic acids having 7 to 14 carbon atoms include benzoic acid. The aromatic carboxylic acids may be used alone or in combination.

[0045] The ester of an alkylene oxide adduct of an aromatic compound having a hydroxyl group and a carboxylic acid is not particularly limited, and examples thereof include an ester of bisphenol A adducted with 1 to 20 moles of polyoxyalkylene and a fatty acid, and an ester of distyrenated phenol adducted with 1 to 20 moles of polyoxyalkylene and a fatty acid. From the viewpoint of improving the sizing ability during flame retardation, an ester of bisphenol A adducted with 1 to 20 moles of polyoxyethylene and a fatty acid is preferred.

[0046] [Brønsted Acid Compound (D)] The treatment agent of the present invention preferably contains a Brønsted acid compound (D) in that emulsion stability is improved. The Brønsted acid compound (D) refers to a proton donor, and examples of the Brønsted acid compound (D) include organic carboxylic acid compounds, inorganic acids, organic sulfonic acid compounds, organic phosphate ester compounds, organic sulfate ester compounds, and organic phosphonic acid compounds.

[0047] The organic carboxylic acid compound refers to an organic compound having a carboxyl group in its molecular structure. Examples of the organic carboxylic acid compound include, but are not limited to, aliphatic monocarboxylic acids, alkyl ether carboxylic acids, aliphatic polycarboxylic acids, aromatic carboxylic acids, aromatic polycarboxylic acids, and amino acids.

[0048] Examples of aliphatic monocarboxylic acids include acetic acid, lactic acid, butyric acid, crotonic acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, myristoleic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, isocetyl acid, margaric acid, stearic acid, isostearic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, arachidic acid, isoeicosalic acid, gadoleic acid, eicosenoic acid, docosanoic acid, isodocosanoic acid, erucic acid, tetracosanoic acid, isotetracosanoic acid, nervonic acid, cerotic acid, montanic acid, and melissic acid.

[0049] Examples of alkyl ether carboxylic acids include those in which the alkyl group has 8 to 18 carbon atoms and the number of moles of polyoxyalkylene added is 1 to 50. Examples of the alkyl group include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. Examples of the polyoxyalkylene group include polyoxyethylene, polyoxypropylene, and polyoxyethylenepolyoxypropylene groups.

[0050] Aliphatic polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, pentadecanedioic acid, and derivatives thereof.

[0051] The aromatic monocarboxylic acids include benzoic acid, cinnamic acid, naphthoic acid, toluic acid, and derivatives thereof.

[0052] Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and derivatives thereof.

[0053] An amino acid is a compound that has both an amino group and a carboxyl group in its molecular structure, and examples thereof include alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline, glycine, tyrosine, serine, threonine, cysteine, asparagine, glutamine, lysine, arginine, histidine, aspartic acid, and glutamic acid.

[0054] Inorganic acids are acids containing non-metallic atoms, such as sulfuric acid, nitric acid, phosphoric acid, and hydrochloric acid.

[0055] Examples of the organic sulfonic acid compound include alkylbenzene sulfonic acid, polyoxyalkylene alkyl ether sulfonic acid, higher fatty acid amide sulfonic acid, alkyl sulfate monoester, and polyoxyalkylene sulfate monoester.

[0056] Examples of the organic phosphate ester compound include alkyl phosphate monoesters, alkyl phosphate diesters, polyoxyalkylene alkyl ether phosphate monoesters, polyoxyalkylene alkyl ether phosphate diesters, polyoxyalkylene alkyl phenyl ether phosphate monoesters, and polyoxyalkylene alkyl phenyl ether phosphate diesters.

[0057] Examples of the organic sulfate compound include alkyl sulfate, polyoxyalkylene alkyl sulfate, alkylphenyl sulfate, and polyoxyalkylene alkylphenyl sulfate.

[0058] Examples of the organic phosphonic acid compound include alkyl phosphonic acid, aromatic phosphonic acid, and polyoxyalkylene alkyl ether phosphonic acid.

[0059] The pKa of the Bronsted acid compound (D) is preferably 0 to 7, more preferably 1 to 6.5, and even more preferably 2 to 6, from the viewpoints of corrosion and safety of equipment and of suppressing crosslinking over time due to the amino group of the amino-modified silicone.

[0060] In terms of improving emulsion stability, the Brønsted acid compound (D) preferably contains at least one selected from an organic carboxylic acid compound, an inorganic acid, and an organic phosphate compound, more preferably contains at least one selected from lactic acid, an alkyl ether carboxylic acid, an organic phosphate compound, phosphoric acid, and acetic acid, and even more preferably contains at least one selected from an alkyl ether carboxylic acid, an organic phosphate compound, acetic acid, and phosphoric acid. One or more Brønsted acid compounds (D) may be used.

[0061] [Silicone Having a Polyether Group] The treatment agent of the present invention contains a silicone having a polyether group. The silicone having a polyether group has an inorganic siloxane bond (—Si—O—Si—) in its main chain and a polyether group in at least one of the main chain, side chain, and terminal, and is not particularly limited as long as it is other than the silicone (A) having an amino group. As the silicone having a polyether group, known silicones having a polyether group can be appropriately used. Examples of silicones having a polyether group include ABn-type polyether-modified silicones, side-chain-type polyether-modified silicones, both-end-type polyether-modified silicones, alkyl polyether-modified silicones in which both a polyether group and an alkyl group have been introduced into the side chain or terminal, side-chain-type polyether-modified silicones in which the polyether chain terminals are blocked with an aliphatic compound or a fatty acid compound, and both-end-type polyether-modified silicones in which the polyether chain terminals are blocked with an aliphatic compound or a fatty acid compound. One or more types of silicones having a polyether group may be used.

[0062] The total weight ratio of oxypropylene (hereinafter sometimes referred to as PO) units and oxyethylene (hereinafter sometimes referred to as EO) units to the weight of the silicone having a polyether group is preferably 5 to 95% by weight, from the viewpoints of penetration into the interior of the fiber bundle and stability of the treatment agent in an aqueous system. The upper limit of this ratio is more preferably 90% by weight, even more preferably 85% by weight, and particularly preferably 80% by weight. Meanwhile, the lower limit of this ratio is more preferably 10% by weight, even more preferably 15% by weight, and particularly preferably 20% by weight. Furthermore, for example, 10 to 95% by weight is more preferable, 15 to 95% by weight is more preferable, and 20 to 90% by weight is particularly preferable.

[0063] The weight ratio of EO units to PO units (EO / PO) contained in the silicone having a polyether group is preferably 0.05 to 95 in terms of penetrability into the interior of the fiber bundle. The upper limit of this ratio is more preferably 75, even more preferably 50, and particularly preferably 20. On the other hand, the lower limit of this ratio is more preferably 0.1, even more preferably 0.3, and particularly preferably 1.0. Also, for example, it is more preferably 0.1 to 50, and even more preferably 0.1 to 20. Here, the total proportion of PO units and EO units in the silicone having a polyether group and the weight ratio of EO units to PO units contained in the silicone having a polyether group (EO / PO) refer to the total weight proportion and weight ratio of all PO units and EO units contained in the silicone having a polyether group, and are used to refer to the silicone having a polyether group. １ It refers to the value calculated from the weight ratio of PO units and EO units to the weight of silicone having polyether groups, which is calculated from the peak area when measured by H-NMR.

[0064] The HLB (Hydrophile-Lipophile Balance) value, which represents the hydrophilic-lipophilic balance of the silicone having a polyether group, is not particularly limited, but is preferably 4 to 16 from the viewpoint of the stability of the treatment agent in an aqueous system. The upper limit of the HLB is more preferably 15, even more preferably 14, and particularly preferably 12. On the other hand, the lower limit of the HLB is more preferably 6, even more preferably 7, and particularly preferably 8. For example, 7 to 16 is more preferable, and 7 to 14 is even more preferable. The HLB in the present invention is a value calculated from the haze number A measured as follows, using the following formula: HLB = haze number A × 0.89 + 1.11 <Method for Measuring Haze Number A> The haze number A is measured as follows, in accordance with the known method described in "Surfactant Handbook," pages 324-325 (published by Sangyo Tosho Co., Ltd. on July 5, 1960). Weigh out 2.5 g of anhydrous polyether group-containing silicone, add 98% ethanol to a constant volume of 25 ml (using a 25 ml measuring flask). Next, use a 5 ml volumetric pipette to dispense this, place it in a 50 ml beaker, and while maintaining the temperature at 25 ° C and stirring (using a magnetic stirrer), measure the cloudiness of 2% aqueous phenol solution using a 25 ml burette. The point at which the solution becomes cloudy is the endpoint, and the number of ml of 2% aqueous phenol solution required for this titration is taken as the cloudiness number A.

[0065] The kinematic viscosity of the silicone having a polyether group at 25°C is 10 to 10,000 mm in terms of its ability to penetrate into the fiber bundle. ２ The upper limit of the kinematic viscosity is more preferably 8000 mm ２ / s, more preferably 7000 mm ２ / s, particularly preferably 5000 mm ２ On the other hand, the lower limit of the kinematic viscosity is more preferably 50 mm ２ / s, more preferably 100 mm ２ / s, particularly preferably 150 mm ２ / s. For example, 50 to 5000 mm ２ / s is more preferable, and 100 to 5000 mm ２ / s is more preferred.

[0066] The polyether group-containing silicone may be a combination of multiple polyether group-containing silicones with different HLBs and kinematic viscosities (25°C). When two or more types of polyether group-containing silicones are used, the above HLB refers to the HLB of the entire polyether group-containing silicones (mixture), and the above kinematic viscosity at 25°C refers to the kinematic viscosity of the entire polyether group-containing silicones (mixture).

[0067] [Treatment Agent for Carbon Fiber Precursors] The treatment agent for carbon fiber precursors of the present invention contains a silicone (A) having an amino group, a silicone (B) having an aryl group, and an aliphatic (poly)oxyalkylene derivative (C1).

[0068] The reason why the treating agent for carbon fiber precursors of the present invention contains the silicone (A) having an amino group, the silicone (B) having an aryl group, and the aliphatic (poly)oxyalkylene derivative (C1), and when the carbon fiber precursor produced by applying the treating agent is stored for a long period of time, deterioration of the carbon fiber precursor can be suppressed is believed to be because the silicone (B) having an aryl group and the aliphatic (poly)oxyalkylene derivative (C1) form a protective layer on the surface of the carbon fiber precursor, suppressing crosslinking over time caused by oxidation of the amino group of the silicone (A) having an amino group.

[0069] The proportion of the amino group-containing silicone (A) in the non-volatile content of the treating agent of the present invention is preferably 0.1 to 95% by weight, from the viewpoints of easily suppressing deterioration over time of the carbon fiber precursor and facilitating emulsion stabilization. The upper limit of this proportion is more preferably 92% by weight, even more preferably 88% by weight, and particularly preferably 85% by weight. Meanwhile, the lower limit of this proportion is more preferably 1% by weight, even more preferably 3% by weight, and particularly preferably 5% by weight. Furthermore, for example, 1 to 92% by weight is more preferable, 3 to 88% by weight is even more preferable, and 5 to 85% by weight is particularly preferable. The non-volatile content concentration in the present invention is determined by spreading 2.0 to 3.0 g of the treatment agent evenly on an aluminum sheet (φ110 mm), drying at 110°C under irradiation with an infrared lamp, accurately weighing the weight of the residue on the aluminum sheet when the fluctuation range of the volatile content over 150 seconds is 0.15%, and calculating the ratio (percentage) of the remaining weight after heating to the weight before heating. The non-volatile content in the present invention refers to the residue on the aluminum sheet when the fluctuation range of the volatile content over 150 seconds is 0.15%, which was determined in the same manner as in the non-volatile content concentration measurement procedure.

[0070] The proportion of the aryl group-containing silicone (B) in the non-volatile content of the treating agent of the present invention is preferably 60% by weight or less, from the viewpoints of easily suppressing deterioration over time of the carbon fiber precursor and facilitating emulsion stabilization. The upper limit of this proportion is more preferably 50% by weight, even more preferably 30% by weight, and particularly preferably 15% by weight. Meanwhile, the lower limit of this proportion is more preferably 0.5% by weight, even more preferably 1% by weight, and particularly preferably 1.5% by weight. Furthermore, for example, 0.5 to 50% by weight is more preferable, 1 to 30% by weight is even more preferable, and 1.5 to 15% by weight is particularly preferable.

[0071] The proportion of the aliphatic (poly)oxyalkylene derivative (C1) in the non-volatile content of the treating agent of the present invention is preferably 1 to 90% by weight, from the viewpoints of easily suppressing deterioration over time of the carbon fiber precursor and easily stabilizing the emulsion. The upper limit of this proportion is more preferably 70% by weight, even more preferably 40% by weight, and particularly preferably 30% by weight. On the other hand, the lower limit of this proportion is more preferably 3% by weight, even more preferably 5% by weight, and particularly preferably 7% by weight. Furthermore, for example, 3 to 70% by weight is more preferable, 5 to 40% by weight is even more preferable, and 7 to 30% by weight is particularly preferable.

[0072] The weight ratio (B / A) of the aryl group-containing silicone (B) to the amino group-containing silicone (A) is preferably 1 or less, from the viewpoints of easily suppressing deterioration over time of the carbon fiber precursor and easily stabilizing the emulsion. The upper limit of this ratio is more preferably 0.9, even more preferably 0.7, particularly preferably 0.5, and most preferably 0.48. On the other hand, the lower limit of this weight ratio is more preferably 0.005, even more preferably 0.008, and particularly preferably 0.01. Furthermore, for example, 0.005 to 0.9 is more preferable, 0.008 to 0.7 is even more preferable, 0.01 to 0.5 is particularly preferable, and 0.01 to 0.48 is most preferable.

[0073] The weight ratio (B / C1) of the aryl group-containing silicone (B) to the aliphatic (poly)oxyalkylene derivative (C1) is preferably 9 or less, from the viewpoints of easily suppressing deterioration over time of the carbon fiber precursor and easily stabilizing the emulsion. The upper limit of this ratio is more preferably 7, even more preferably 5, particularly preferably 4, and most preferably 1.7. On the other hand, the lower limit of this weight ratio is more preferably 0.01, even more preferably 0.05, and particularly preferably 0.1. Furthermore, for example, 0.01 to 7 is more preferable, 0.05 to 5 is even more preferable, 0.1 to 4 is particularly preferable, and 0.1 to 1.7 is most preferable.

[0074] When the treatment agent of the present invention further contains a Brønsted acid compound (D), the proportion of the Brønsted acid compound (D) in the non-volatile content of the treatment agent of the present invention is preferably 0.05 to 10 wt %, in order to facilitate emulsion stabilization. The upper limit of this weight proportion is more preferably 8.5 wt %, even more preferably 7 wt %, and particularly preferably 5 wt %. Meanwhile, the lower limit of this weight proportion is more preferably 0.07 wt %, even more preferably 0.08 wt %, and particularly preferably 0.1 wt %. Furthermore, for example, 0.07 to 7 wt % is more preferable, and 0.1 to 5 wt % is even more preferable.

[0075] The proportion of silicone having a polyether group in the non-volatile content of the treatment agent of the present invention is preferably 0 to 10 wt % in terms of facilitating emulsion stabilization. The upper limit of this weight percentage is more preferably 8.5 wt %, even more preferably 7 wt %, and particularly preferably 5 wt %. Meanwhile, the lower limit of this weight percentage is more preferably 0.07 wt %, even more preferably 0.08 wt %, and particularly preferably 0.1 wt %. Furthermore, for example, 0.07 to 7 wt % is more preferable, and 0.1 to 5 wt % is even more preferable.

[0076] [Other Component (E)] The treatment agent of the present invention preferably further contains another nonionic surfactant as the other component (E) in order to enhance emulsion stability. The other nonionic surfactant refers to a nonionic surfactant other than the aliphatic (poly)oxyalkylene derivative (C1) and the aromatic (poly)oxyalkylene derivative (C2). Examples of the other nonionic surfactant include sorbitan esters such as sorbitan monopalmitate and sorbitan monooleate; glycerin fatty acid esters such as glycerin monostearate, glycerin monolaurate, and glycerin monopalmitate; and sucrose fatty acid esters. The weight-average molecular weight of the other nonionic surfactant is preferably 2,000 or less, more preferably 200 to 1,800, more preferably 300 to 1,500, and even more preferably 500 to 1,000. One or more types of the other nonionic surfactant may be used.

[0077] When the treatment agent of the present invention contains other nonionic surfactants, the weight ratio of the other nonionic surfactants to the nonvolatile content of the treatment agent is preferably 0.1 to 10 wt % in terms of emulsion stability. The upper limit of this ratio is more preferably 8.5 wt %, even more preferably 7.0 wt %, and particularly preferably 5.0 wt %. Meanwhile, the lower limit of this ratio is more preferably 0.25 wt %, even more preferably 0.4 wt %, and particularly preferably 0.5 wt %. Furthermore, for example, 0.25 to 8.5 wt % is more preferable, 0.4 to 7.0 wt % is even more preferable, and 0.5 to 5.0 wt % is particularly preferable.

[0078] The pH of the treatment agent of the present invention when diluted to 1.0 wt % nonvolatile content is preferably 4 to 8, from the viewpoint of long-term storage stability of the treatment agent. The upper limit of the pH is more preferably 7, and even more preferably 6.5. On the other hand, the lower limit of the content is more preferably 4.5, and even more preferably 5. Also, for example, 4.5 to 6.5 is more preferable, and 5 to 6.5 is even more preferable. The pH of the treatment agent of the present invention when diluted to 1.0 wt % nonvolatile content is determined by the method described in the Examples.

[0079] [Other Surfactants] The treatment agent of the present invention may contain surfactants other than the aliphatic (poly)oxyalkylene derivative (C1), aromatic (poly)oxyalkylene derivative (C2), Bronsted acid compound (D), and other nonionic surfactants, as long as the effects of the present invention are not impaired. The other surfactants are used as emulsifiers, antistatic agents, etc. The other surfactants are not particularly limited, and known surfactants can be appropriately selected and used from anionic surfactants, cationic surfactants, and amphoteric surfactants. The surfactant may be used alone or in combination of two or more.

[0080] Examples of anionic surfactants include ether carboxylates, ether sulfates, sulfosuccinates, (poly)oxyethylene coconut oil fatty acid monoethanolamide sodium sulfate, sulfonates having an alkyl group, phosphates having an alkyl group, fatty acid salts, acylated amino acid salts, and amine-neutralized products of fatty acids.

[0081] Examples of cationic surfactants include alkyl quaternary ammonium salts such as lauryl trimethyl ammonium chloride, myristyl trimethyl ammonium chloride, palmityl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, oleyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, coconut oil alkyl trimethyl ammonium chloride, beef tallow alkyl trimethyl ammonium chloride, stearyl trimethyl ammonium bromide, coconut oil alkyl trimethyl ammonium bromide, cetyl trimethyl ammonium methosulfate, oleyl dimethyl ethyl ammonium ethosulfate, dioctyl dimethyl ammonium chloride, dilauryl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, and octadecyl diethyl methyl ammonium sulfate; N-(2-hydroxyethyl)-N,N-dimethyl-N-sulfate; acylamidoalkyl quaternary ammonium salts such as tearamidopropyl ammonium nitrate, lanolin fatty acid amidopropylethyl dimethylammonium ethosulfate, and lauroylamidoethyl methyldiethylammonium methosulfate; alkylisoquinolinium salts such as laurylisoquinolinium chloride; benzalkonium salts such as lauryldimethylbenzyl ammonium chloride and stearyldimethylbenzyl ammonium chloride; pyridinium salts such as cetylpyridinium chloride; imidazolinium salts such as oleylhydroxyethylimidazolinium ethosulfate and laurylhydroxyethylimidazolinium ethosulfate; acyl basic amino acid alkyl ester salts such as N-cocoylarginine ethyl ester pyrrolidone carboxylate and N-lauroyllysine ethyl ethyl ester chloride; primary amine salts such as laurylamine chloride, stearylamine bromide, hardened beef tallow alkylamine chloride, and rosinamine acetate;Examples of the amine salts include secondary amine salts such as cetylmethylamine sulfate, laurylmethylamine chloride, dilaurylamine acetate, stearylethylamine bromide, laurylpropylamine acetate, dioctylamine chloride, and octadecylethylamine hydroxide; tertiary amine salts such as dilaurylmethylamine sulfate, lauryldiethylamine chloride, laurylethylmethylamine bromide, diethanolstearylamidoethylamine trihydroxyethylphosphate salt, and stearylamidoethylethanolamine urea polycondensate acetate salt; fatty acid amide guanidinium salts; and alkyltrialkyleneglycolammonium salts such as lauryltriethyleneglycolammonium hydroxide.

[0082] Examples of amphoteric surfactants include imidazoline-based amphoteric surfactants such as 2-undecyl-N,N-(hydroxyethylcarboxymethyl)-2-imidazoline sodium and 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt; betaine-based amphoteric surfactants such as 2-heptadecyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, lauryl dimethylaminoacetic acid betaine, alkyl betaine, amido betaine, and sulfobetaine; and amino acid-based amphoteric surfactants such as N-lauryl glycine, N-lauryl β-alanine, and N-stearyl β-alanine.

[0083] [Other Components] The treating agent for carbon fiber precursors of the present invention may contain other components in addition to the above-mentioned components, as long as the effects of the present invention are not impaired. Examples of other components include antioxidants such as phenols, amines, sulfurs, phosphorus, and quinones; antistatic agents such as quaternary ammonium salt-type cationic surfactants and amine salt-type cationic surfactants; smoothing agents such as alkyl esters of higher alcohols, higher alcohol ethers, and waxes; antibacterial agents; preservatives; rust inhibitors; and moisture absorbents.

[0084] The treatment agent of the present invention may also contain one or more low molecular weight silicones. Examples of low molecular weight silicones include linear or cyclic silicones having 2 to 7 silicon atoms. Specific examples of low molecular weight silicones include octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, heptamethyloctyltrisiloxane, hexamethyldisiloxane, decamethyltetrasiloxane, and dodecamethylpentasiloxane. These low molecular weight silicones may be substituted with a group represented by the general formula (2) above. These low molecular weight silicones may be included as trace components of the amino group-containing silicone (A) and / or aryl group-containing silicone (B). The content of the low molecular weight silicone in the treatment agent of the present invention is preferably 5 parts by weight or less per 100 parts by weight of the amino group-containing silicone (A) and aryl group-containing silicone (B).

[0085] The carbon fiber precursor treatment agent of the present invention is preferably in a state in which the amino group-containing silicone (A), the aryl group-containing silicone (B), and the aliphatic (poly)oxyalkylene derivative (C1), as well as, if necessary, the aromatic (poly)oxyalkylene derivative (C2), the Brønsted acid compound (D), and other components (E) are dissolved, solubilized, emulsified, or dispersed in water. The weight percentage of water and the weight percentage of nonvolatile matter in the entire carbon fiber precursor treatment agent are not particularly limited. These may be determined appropriately taking into account, for example, the transportation costs for transporting the carbon fiber precursor treatment agent of the present invention and the ease of handling due to the emulsion viscosity. The weight percentage of water in the entire carbon fiber precursor treatment agent is preferably 0.1 to 99.9 wt %, more preferably 10 to 99.5 wt %, and particularly preferably 50 to 99 wt %. The weight ratio (concentration) of the nonvolatile matter in the entire carbon fiber precursor treating agent is preferably 0.01 to 99.9% by weight, more preferably 0.5 to 90% by weight, and particularly preferably 1 to 50% by weight.

[0086] The treating agent for carbon fiber precursors of the present invention can be produced by mixing the components described above. The method for emulsifying and dispersing the components described above is not particularly limited, and known techniques can be used. Examples of such methods include a method in which each component constituting the treating agent for carbon fiber precursors is added to warm water under stirring to emulsify and disperse the components, and a method in which each component constituting the treating agent for carbon fiber precursors is mixed and then subjected to mechanical shear force using a homogenizer, homomixer, ball mill, or the like while gradually adding water to perform phase inversion emulsification. Alternatively, a method in which some components are emulsified and then the remaining components are dissolved and dispersed may be used.

[0087] The treating agent for carbon fiber precursors of the present invention can be suitably used as a treating agent for carbon fiber precursors.

[0088] [Carbon fiber precursor, its manufacturing method, and carbon fiber manufacturing method] The carbon fiber precursor of the present invention is obtained by adhering the above-mentioned carbon fiber precursor treating agent to a raw material carbon fiber precursor of a carbon fiber precursor and spinning it into a fiber. The method for manufacturing a carbon fiber precursor of the present invention includes a spinning step of adhering the above-mentioned carbon fiber precursor treating agent to a raw material carbon fiber precursor of a carbon fiber precursor and spinning it into a fiber. The method for manufacturing a carbon fiber of the present invention includes a flame-resistant treatment step of converting the carbon fiber precursor having the above-mentioned carbon fiber precursor treating agent adhered thereto into a flame-resistant fiber, and a carbonization treatment step of further carbonizing the flame-resistant fiber. The flame-resistant treatment step is preferably a flame-resistant treatment step of converting the carbon fiber precursor into a flame-resistant fiber in an oxidizing atmosphere at 200 to 300°C, and the carbonization treatment step is preferably a step of further carbonizing the flame-resistant fiber in an inert atmosphere at 300 to 2000°C. According to the carbon fiber manufacturing method of the present invention, the treatment agent for carbon fiber precursor of the present invention is used, which improves bundling ability, reduces fiber bundle disorder and uneven drawing, and enables the production of high-quality carbon fibers.

[0089] The spinning process is a process of spinning a carbon fiber precursor by adhering a treatment agent for a carbon fiber precursor to a raw material carbon fiber precursor of the carbon fiber precursor, and preferably includes an adhering process and a drawing process. The adhering process is a process of adhering a treatment agent for a carbon fiber precursor after spinning the raw material carbon fiber precursor of the carbon fiber precursor. That is, in the adhering process, the treatment agent for a carbon fiber precursor is adhered to the raw material carbon fiber precursor of the carbon fiber precursor. Furthermore, when the raw material carbon fiber precursor of the carbon fiber precursor is stretched immediately after spinning, the high-magnification drawing after the adhering process is particularly referred to as the "drawing process." The drawing process may be a wet heat drawing method using high-temperature steam, or a dry heat drawing method using a heated roller. The draw ratio in the drawing process is preferably 2 to 20 times the total draw ratio of the raw material carbon fiber precursor immediately after spinning.

[0090] The carbon fiber precursor is preferably composed of acrylic fibers whose main component is polyacrylonitrile obtained by copolymerizing at least 95 mol% or more of acrylonitrile and 5 mol% or less of a flame retardant-promoting component. A vinyl group-containing compound copolymerizable with acrylonitrile can be suitably used as the flame retardant-promoting component. The single fiber fineness of the carbon fiber precursor is not particularly limited, but is preferably 0.1 to 2.0 dtex in view of the balance between performance and production costs. The number of single fibers constituting the fiber bundle of the carbon fiber precursor is also not particularly limited, but is preferably 1,000 to 96,000 in view of the balance between performance and production costs.

[0091] The treating agent for carbon fiber precursors may be applied to the raw material carbon fiber precursor of the precursor at any stage in the spinning process, but is preferably applied once before the drawing process. It may be applied at any stage before the drawing process, for example, immediately after spinning. It may also be applied again at any stage after the drawing process, for example, immediately after the drawing process, or at the winding stage, or immediately before the flame retardant treatment process. The application method may be by using a roller or the like, or by a dipping method, spraying method, or the like.

[0092] In the adhesion treatment step, the application rate of the treatment agent for carbon fiber precursors is preferably 0.1 to 5 wt %, more preferably 0.3 to 1.5 wt %, based on the weight of the carbon fiber precursor, in order to strike a balance between obtaining an effect of preventing fiber-to-fiber sticking and fusion, and preventing deterioration in the quality of the carbon fiber due to tar products of the treatment agent in the carbonization treatment step. Note that the application rate of the treatment agent for carbon fiber precursors here is defined as the percentage of the weight of the nonvolatile content of the treatment agent for carbon fiber precursors adhered to the weight of the carbon fiber precursor.

[0093] The flame-resistant treatment step is a step of converting a carbon fiber precursor having a carbon fiber precursor treating agent attached thereto into a flame-resistant fiber in an oxidizing atmosphere at, for example, 200 to 300°C. The oxidizing atmosphere may typically be an air atmosphere. The temperature of the oxidizing atmosphere is preferably 230 to 280°C. In the flame-resistant treatment step, the carbon fiber precursor after the attachment treatment is heat-treated for 20 to 100 minutes (preferably 30 to 60 minutes) while applying a tension at a draw ratio of 0.90 to 1.10 (preferably 0.95 to 1.05). In this flame-resistant treatment, a flame-resistant fiber having a flame-resistant structure is produced through intramolecular cyclization and oxygen addition to the ring.

[0094] The carbonization step is a step in which the flame-resistant fiber is further carbonized in an inert atmosphere at, for example, 300 to 2000°C. In the carbonization step, it is preferable to first perform a preliminary carbonization step (first carbonization step) in which the flame-resistant fiber is heat-treated for several minutes in an inert atmosphere such as nitrogen or argon in a baking furnace having a temperature gradient from 300 to 800°C while applying a tension at a draw ratio of 0.95 to 1.15. Thereafter, to further promote carbonization and graphitization, the flame-resistant fiber is heat-treated for several minutes in an inert atmosphere such as nitrogen or argon while applying a tension at a draw ratio of 0.95 to 1.05, which is the same as that in the first carbonization step, to perform a second carbonization step, thereby carbonizing the flame-resistant fiber. Regarding the control of the heat treatment temperature in the second carbonization step, it is preferable to set the maximum temperature to 1000°C or higher (preferably 1000 to 2000°C) while applying a temperature gradient. This maximum temperature is appropriately selected and determined depending on the desired properties (tensile strength, modulus of elasticity, etc.) of the carbon fiber.

[0095] In the method for producing carbon fibers of the present invention, if a carbon fiber with an even higher elastic modulus is desired, a graphitization step can be carried out subsequent to the carbonization step. The graphitization step is usually carried out in an inert atmosphere such as nitrogen or argon at a temperature of 2000 to 3000°C while applying tension to the fiber obtained in the carbonization step.

[0096] The carbon fibers obtained in this manner can be surface-treated depending on the purpose to enhance the adhesive strength with the matrix resin when they are made into a composite material. Gas-phase or liquid-phase treatments can be used as the surface treatment method, and from the viewpoint of productivity, liquid-phase treatments using an electrolyte such as an acid or alkali are preferred. Furthermore, various sizing agents that are highly compatible with the matrix resin can be added to improve the processability and handling of the carbon fibers.

[0097] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In the following examples, percentages (%) and parts are by weight unless otherwise specified. Measurements of each property were carried out according to the methods described below.

[0098] <pH of diluted solution with 1.0% nonvolatile content by weight> Each treatment agent was diluted with ion-exchanged water to a nonvolatile content concentration of 1.0% by weight, and the pH of the aqueous dispersion at 25°C was measured.

[0099] <Applied rate of treatment agent> The carbon fiber precursor to which the treatment agent had been applied was alkali-fused with potassium hydroxide / sodium butyrate, then dissolved in water and adjusted to pH 1 with hydrochloric acid. Sodium sulfite and ammonium molybdate were added to this to develop color, and colorimetric determination (wavelength 815 mμ) of silicomolybdenum blue was performed to determine the silicon content. The applied rate (wt%) of the carbon fiber precursor treatment agent was calculated using the silicon content determined here and the silicon content in the treatment agent previously determined by the same method.

[0100] <Number of fluffs in carbon fiber bundle> Carbon fibers were produced using carbon fiber precursors stored under the following two conditions, and the number of fluffs was measured by the following method. Storage condition 1: Stored at room temperature for 7 days. Storage condition 2: Stored at room temperature for 12 months. The carbon fiber bundle was pulled out from the bobbin without tension, and any fluff was collected until the number reached 50. The length of the carbon fiber bundle pulled out until 50 fluffs were collected was measured, and the number of fluffs per unit length (fuzz / m) was calculated from the measured length of the carbon fiber bundle as the number of fluffs present on the surface of the carbon fiber bundle, and ⊚ and ◯ were evaluated as pass. ⊚: The number of fluffs was less than 3 fluffs / m, and the number of fluffs was particularly good with little fluff. ◯: The number of fluffs was 3 fluffs / m or more but less than 10 fluffs / m, and the number of fluffs was good with little fluff. ×: The number of fluffs was 10 fluffs / m or more, and the number of fluffs was poor with much fluff.

[0101] <Carbon fiber strength> Carbon fibers were produced using carbon fiber precursors stored under the following two conditions, and measurements were performed in accordance with the test method for tensile properties of single fibers specified in JIS-R-7606. The average value of 10 measurements was taken as the carbon fiber strength (GPa). Storage condition 1: Stored at room temperature for 7 days. Storage condition 2: Stored at room temperature for 12 months. The maintenance rate of carbon fiber strength after changes over time was calculated using the following formula: (Maintenance rate (%)) = (Strength of carbon fiber produced using carbon fiber precursor after storage at room temperature for 12 months) / (Strength of carbon fiber produced using carbon fiber precursor after storage at room temperature for 7 days) × 100

[0102] <Deterioration Inhibition of Carbon Fiber Precursor> In the evaluation of the fluff and carbon fiber strength of the carbon fiber bundle, the deterioration inhibition of the carbon fiber precursor was judged according to the following criteria. Pass was marked with ◯, and fail was marked with ×. Pass criteria: The number of fluff of the carbon fiber bundle was ◯ or more under both storage condition 1 and storage condition 2, and the maintenance rate of carbon fiber strength was 95% or more.

[0103] Example 1: Amino group-containing silicone (A), aryl group-containing silicone (B), and aliphatic (poly)oxyalkylene derivative (C1) were mixed to obtain the nonvolatile composition of the treatment agent shown in Table 1. The temperature of the mixture during emulsification was adjusted to 60-80°C, and emulsification was carried out by gradually adding water while stirring using a stirring blade at a blade tip speed of 3 m / s. The weight percentage of silicone A in the nonvolatile content of the treatment agent was 75 wt%, the weight percentage of aryl group-containing silicone (B) was 5 wt%, and the weight percentage of aliphatic (poly)oxyalkylene derivative (C1) was 20 wt%. The prepared treatment agent was then further diluted with water to obtain a diluted solution with a nonvolatile content of 3.0 wt%. The dilution solution was applied to a raw material carbon fiber precursor obtained by copolymerizing 97 mol% acrylonitrile and 3 mol% itaconic acid, so that the non-volatile content of the treatment agent was 1.0 wt%. The resulting carbon fiber precursor was then subjected to a drawing process (steam drawing, draw ratio 2.1 times) to produce a carbon fiber precursor (single fiber fineness 0.8 dtex, 24,000 filaments). This carbon fiber precursor was subjected to a flame-resistant treatment in a 250°C flame-resistant furnace for 60 minutes, and then calcined in a carbonization furnace with a temperature gradient of 300 to 1400°C under a nitrogen atmosphere to convert it into carbon fiber. The results of evaluation of each property value are shown in Table 1.

[0104] [Examples 2 to 42, Comparative Examples 1 to 11] The nonvolatile composition was changed as shown in Tables 1 to 4, and when a Bronsted acid compound (D) was added, the treatment agent was prepared by dissolving and dispersing it after emulsification. Otherwise, treatment agents for carbon fiber precursors, carbon fiber precursors, and carbon fibers were prepared and evaluated in the same manner as in Example 1. The results of evaluating each property value are shown in Tables 1 to 4.

[0105]

[0106]

[0107]

[0108]

[0109] The details of the nonvolatile composition in Tables 1 to 4 are as follows: <Silicone (A) having an amino group> Amino-modified silicone a1: kinematic viscosity at 25°C: 10,000 mm ２ / s, amino equivalent: 3600 g / mol, side chain diamine type amino-modified silicone a2: 25 ° C. kinematic viscosity: 1500 mm ２ / s, amino equivalent: 3800 g / mol, side chain diamine type amino-modified silicone a3: 25°C kinematic viscosity: 250 mm ２ / s, amino equivalent: 7600 g / mol, side chain diamine type amino-modified silicone a4: 25 °C kinematic viscosity: 1700 mm ２ / s, amino equivalent: 3800 g / mol, side chain monoamine type aminopolyether modified silicone a5: 25°C kinematic viscosity: 3300 mm ２ / s, amino equivalent: 1800 g / mol, side chain amino polyether type

[0110] <Silicone (B) having an aryl group> Diphenylsilicone b1: kinematic viscosity at 25°C: 100 mm ２ / s (phenyl group:methyl group = 5:95 (molar ratio)) Diphenyl silicone b2: 25 °C kinematic viscosity: 170 mm ２ / s (phenyl group: methyl group = 28:72 (molar ratio)) Diphenyl silicone b3: 25 ° C. kinematic viscosity: 3000 mm ２ / s (phenyl group:methyl group = 5:95 (molar ratio)) Aralkyl-modified silicone b4: 25 °C kinematic viscosity: 900 mm ２ / s

[0111] <Aliphatic (poly)oxyalkylene derivative (C1)> Aliphatic (poly)oxyalkylene derivative c1-1: a secondary alkyl ether having 12 to 14 carbon atoms in the alkyl group to which 5 moles of oxyethylene groups have been added. Aliphatic (poly)oxyalkylene derivative c1-2: a secondary alkyl ether having 12 to 14 carbon atoms in the alkyl group to which 9 moles of oxyethylene groups have been added. Aliphatic (poly)oxyalkylene derivative c1-3: an adduct of 10 moles of ethylene oxide to oleic acid.

[0112] <Aromatic (poly)oxyalkylene derivative (C2)> Aromatic (poly)oxyalkylene derivative c2-1: bisphenol A ether having 10 moles of oxyethylene groups added. Aromatic (poly)oxyalkylene derivative c2-2: bisphenol A ether having 17.5 moles of oxyethylene groups added. Aromatic (poly)oxyalkylene derivative c2-3: esterification product of 1 mole of bisphenol A having 2 moles of oxyethylene groups added with 2 moles of lauric acid.

[0113] <Bronsted acid compound (D)> Bronsted acid compound d1: acetic acid Bronsted acid compound d2: phosphoric acid

[0114] <Silicone having polyether group> Silicone having polyether group p1: kinematic viscosity at 25°C: 130 mm ２ / s, HLB: 4, EO / PO = 40 / 60, side chain polyether modified silicone Silicone p2 having polyether group: 25°C kinematic viscosity: 200 mm ２ / s, HLB: 6, EO / PO=50 / 50, side chain polyether modified silicone

[0115] As can be seen from Tables 1 to 4, the carbon fiber precursor treating agents of Examples 1 to 42 contained an amino group-containing silicone (A), an aryl group-containing silicone (B), and an aliphatic (poly)oxyalkylene derivative (C1), and therefore were able to suppress deterioration of the carbon fiber precursor over time. On the other hand, the carbon fiber precursor treating agents of Comparative Examples 1 to 7 were not the carbon fiber precursor treating agents of the present invention, and therefore were unable to suppress deterioration of the carbon fiber precursor when the carbon fiber precursor produced by applying the treating agent was stored for an extended period of time. The carbon fiber precursor treating agents of Comparative Examples 8 to 11 had poor emulsion stability and did not adhere uniformly to the precursor, preventing normal production of the carbon fiber precursor, and therefore were unable to be used as carbon fiber precursor treating agents.

[0116] The treating agent for carbon fiber precursors of the present invention is a treating agent used in producing a treating agent for carbon fiber precursors, and is useful for producing high-quality carbon fibers. The treating agent for carbon fiber precursors of the present invention is treated with the treating agent of the present invention, and is useful for producing high-quality carbon fibers. High-quality carbon fibers can be obtained by the carbon fiber production method of the present invention.

Claims

1. A treating agent for carbon fiber precursors, containing a silicone having an amino group (A), a silicone having an aryl group (B), and an aliphatic (poly)oxyalkylene derivative (C1).

2. The treating agent for carbon fiber precursors according to claim 1, wherein the weight ratio (B / A) of the silicone having an aryl group (B) to the silicone having an amino group (A) is 1 or less.

3. The treating agent for carbon fiber precursors according to claim 1 or 2, wherein the weight ratio (B / C1) of the silicone having an aryl group (B) to the aliphatic (poly)oxyalkylene derivative (C1) is 9 or less.

4. The treating agent for carbon fiber precursors according to any one of claims 1 to 3, containing an aromatic (poly)oxyalkylene derivative (C2).

5. The treating agent for carbon fiber precursors according to claim 4, wherein the derivative (C2) contains a compound having a bisphenol skeleton.

6. The treating agent for carbon fiber precursors according to any one of claims 1 to 5, wherein the proportion of the silicone having an aryl group (B) in the non-volatile content of the treating agent is 60% by weight or less.

7. The treating agent for carbon fiber precursors according to any one of claims 1 to 6, wherein the silicone having an aryl group (B) contains a silicone having a phenyl group (B1).

8. The treating agent for carbon fiber precursors according to any one of claims 1 to 7, wherein the silicone having an aryl group (B) contains at least one selected from methylphenyl silicone and diphenyl silicone.

9. The treating agent for carbon fiber precursors according to claim 8, wherein the molar ratio (phenyl group:methyl group) of the phenyl group to the methyl group in the methylphenyl silicone and the diphenyl silicone is 1:99 to 90:

10.

10. The treating agent for carbon fiber precursors according to any one of claims 1 to 9, wherein the proportion of the silicone having a polyether group in the non-volatile content of the treating agent is 0 to 10% by weight.

11. The treating agent for carbon fiber precursors according to any one of claims 1 to 10, wherein the pH when it is a 1.0% by weight dilution of the non-volatile content is 4 to 8.

12. A carbon fiber precursor obtained by attaching the treating agent for carbon fiber precursors according to any one of claims 1 to 11 to a raw material carbon fiber precursor of the carbon fiber precursor.

13. A method for producing carbon fibers, comprising a flame-retardant treatment step of converting the carbon fiber precursor according to claim 12 into a flame-retardant fiber, and a carbonization treatment step of further carbonizing the flame-retardant fiber.

Images