Treatment agent for carbon fiber precursor and use thereof

Abstract

An object of the present invention is to provide a treatment agent for a carbon fiber precursor that can reduce fuzz and yarn breakage when a carbon fiber precursor and a carbon fiber are produced even when a treatment agent that has been stored for a long period of time after preparation is used, a carbon fiber precursor using the treatment agent, and a method for producing a carbon fiber using the treatment agent.SOLUTION: The carbon fiber precursor treatment agent of the present invention comprises a silicone (A) and a (poly) oxyalkylene derivative (B), and satisfies the following conditions 1 and 2. Condition 1: The absorbance in 600nm (X1) of an aqueous dispersion having a nonvolatile content of 1 wt% is from 0.07 to 1.0. Condition 2: The absorbance (900nm) at X2 of an aqueous dispersion having a nonvolatile content of 5 wt% is from 0.05 to 0.8.SELECTED DRAWING: None

Description

[Technical Field]

[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. [Background technology]

[0002] Taking advantage of their excellent mechanical properties, carbon fibers are widely used as reinforcing fibers for composite materials with plastics called matrix resins in aerospace, sports, general industrial, and other applications. A typical method for producing carbon fiber involves first producing a carbon fiber precursor (this carbon fiber precursor production process is sometimes referred to as a 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 a flame-resistant treatment process hereinafter), and then carbonized in an inert atmosphere at 300 to 2000°C (this process is sometimes referred to as a carbonization treatment process hereinafter) (the flame-resistant treatment process and carbonization treatment process are sometimes collectively referred to as a baking process hereinafter). During this baking process, fusion between single fibers occurs, which can easily cause problems such as fluffing and yarn breakage, and has been an obstacle to improving productivity.

[0003] In order to prevent the fusing of single fibers during the baking process, a silicone-based treatment agent is applied during the production of the carbon fiber precursor, 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). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2012-46855 [Patent Document 2] Japanese Patent Publication No. 2016-17231 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with such a silicone-based treatment agent, even if there is no problem with the carbon fiber precursor and carbon fiber produced using the treatment agent immediately after preparation, there are cases in which fluffing and thread breakage occur in the carbon fiber precursor and carbon fiber produced using the treatment agent that has been stored for a long period of time after preparation, resulting in a deterioration in productivity. Therefore, an object of the present invention is to provide a treatment agent for carbon fiber precursors that can reduce fuzz and thread breakage when producing carbon fiber precursors and carbon fibers, even when using a treatment agent that has been stored for a long period of time after preparation, a carbon fiber precursor using the treatment agent, and a method for producing carbon fibers using the treatment agent. [Means for solving the problem]

[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 that contains a silicone (A) and a (poly)oxyalkylene derivative (B) and satisfies specific conditions 1 and 2 can reduce fuzz and yarn breakage when producing carbon fiber precursors and carbon fibers, even when the treatment agent has been stored for a long period of time after its preparation.

[0007] That is, the treating agent for carbon fiber precursors of the present invention includes the following embodiments. <1> A treatment agent for carbon fiber precursors, comprising a silicone (A) and a (poly)oxyalkylene derivative (B), and satisfying the following conditions 1 and 2: Condition 1: When the nonvolatile content is dispersed in water at 1% by weight, the absorbance (X1) at 600 nm is 0.07 to 1.0. Condition 2: When the nonvolatile content is dispersed in water at 5% by weight, the absorbance (X2) at 900 nm is 0.05 to 0.8. <2> The non-volatile content of the treatment agent 1In a spectrum measured by H-NMR, the ratio (Y2 / Y1) of the area of ​​a peak (Y2) in the range of -0.3 to 0.3 ppm to the area of ​​a peak (Y1) in the range of 0.4 to 0.7 ppm is 100 to 1200. <1> The treating agent for carbon fiber precursors according to claim 1. <3> The non-volatile content of the treatment agent 1 In a spectrum measured by H-NMR, the ratio (Z2 / Z1) of the area of ​​the peak (Z2) in the range of -0.3 to 0.3 ppm to the area of ​​the peak (Z1) in the range of 3.5 to 4.0 ppm is 5 to 13. <1> or <2> The treating agent for carbon fiber precursors according to claim 1. <4> The treatment agent has a surface tension of 20 to 35 mN / m when dispersed in water at a nonvolatile content of 1% by weight. <1> ~ <3> The treating agent for a carbon fiber precursor according to any one of the preceding claims. <5> The proportion of the silicone (A) in the non-volatile content of the treatment agent is 50% by weight to 95% by weight, and the proportion of the derivative (B) is 5% by weight to 25% by weight. <1> ~ <4> The treating agent for a carbon fiber precursor according to any one of the preceding claims. <6> Further containing a Bronsted acid compound (C), <1> ~ <5> The treating agent for a carbon fiber precursor according to any one of the preceding claims. <7> The derivative (B) includes a compound having a structure in which an alkylene oxide having 2 to 4 carbon atoms is added to at least one selected from alcohols having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups and phenols having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups, <1> ~ <6> The treating agent for a carbon fiber precursor according to any one of the preceding claims. <8> Carbon fiber precursor raw material carbon fiber precursor, <1> ~ <7> 1. A carbon fiber precursor having the treating agent for carbon fiber precursors according to any one of claims 1 to 9 adhered thereto. <9> <8> a flame-resistant treatment step of converting the carbon fiber precursor according to claim 1 into a flame-resistant fiber, and a carbonization treatment step of further carbonizing the flame-resistant fiber. [Effects of the Invention]

[0008] The treating agent for carbon fiber precursors of the present invention can reduce fuzz and thread breakage when producing carbon fiber precursors and carbon fibers, even when a treating agent that has been stored for a long period after preparation is used. According to a carbon fiber precursor using the treating agent for carbon fiber precursors of the present invention and a method for producing carbon fibers using the treating agent, fuzz and thread breakage of carbon fibers can be reduced, even when a treating agent for carbon fiber precursors that has been stored for a long period after preparation is used. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each component of the treating agent for carbon fiber precursors of the present invention (hereinafter sometimes simply referred to as the treating agent) will be described. [Silicone (A)] The treatment agent of the present invention contains a silicone (A). There are no particular limitations on the silicone (A) as long as it has an inorganic siloxane bond (—Si—O—Si—) in its main chain and an organic group in its side chain, but it is preferable for the silicone (A) to contain a modified silicone having a modifying group, in that it exhibits the effects of the present invention, is likely to satisfy conditions 1 and 2, and is likely to satisfy the ratio (Y2 / Y1) of 100 to 1200. Examples of modified silicones include amino-modified silicones, polyether-modified silicones, and aminopolyether-modified silicones, and it is preferable to include at least one selected from amino-modified silicones and aminopolyether-modified silicones, and more preferable to include amino-modified silicones, in order to achieve the effects of the present invention, to easily satisfy conditions 1 and 2, and to easily satisfy (Y2 / Y1) of 100 to 1200. One or more types of silicones can be used.

[0010] The kinematic viscosity of the silicone (A) at 25°C is preferably 50 to 20,000 mm, from the viewpoints of uniform adhesion to fibers, suppression of scattering of the treatment agent, and imparting focusing properties to fibers, easily satisfying conditions 1 and 2, easily satisfying (Y2 / Y1) of 100 to 1,200, and easily satisfying (Z2 / Z1) of 5 to 13. 2 The upper limit of the kinematic viscosity is more preferably 15000 mm 2 / s, and more preferably 10,000 mm 2 / s, particularly preferably 8000 mm2 On the other hand, the lower limit of the kinematic viscosity is more preferably 100 mm 2 / 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, 150 to 10,000 mm 2 / s is even more preferable.

[0011] The amino group (including an organic group having an amino group) that is the modifying group of the amino-modified silicone may be bonded to a side chain of the silicone main chain, to a terminal, or to both, but from the viewpoint of fiber protection in the flame-proofing 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 monoamine type, diamine type, and polyamine type, and both may coexist in one molecule. However, from the viewpoints of uniformly applying the treatment agent to the inside of the fiber bundle in the flame-proofing treatment step and forming a film with the treatment agent to protect the fibers, easily satisfying conditions 1 and 2, and easily satisfying (Y2 / Y1) of 100 to 1200, the monoamine type or diamine type is preferred, and the diamine type is more preferred. The polyether group (including an organic group having a polyoxyalkylene group) that is the modifying group of the polyether-modified silicone may be bonded to a side chain of the silicone main chain, to an end, or to both, but is preferably bonded to a side chain (having a polyether group in the side chain) from the viewpoint of protecting the fiber in the flame-resistant treatment step, making it easier to satisfy conditions 1 and 2, and making it easier to satisfy the ratio (Y2 / Y1) of 100 to 1200. Furthermore, the polyether group preferably contains at least one selected from a polyoxyethylene group, a polyoxypropylene group, and a polyoxyethylene-polyoxypropylene group, in order to form a film with the treatment agent to protect the fiber. Aminopolyether-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).

[0012] The amino equivalent of the amino-modified silicone is preferably 300 to 10,000 g / mol from the viewpoints of preventing adhesion and fusion between fibers, easily satisfying Conditions 1 and 2, and easily satisfying the (Y2 / Y1) ratio of 100 to 1,200. 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, amino equivalent refers to the mass of the siloxane skeleton per amino or ammonium group. The unit of g / mol is the value converted to per 1 mol of amino or ammonium groups. Therefore, the smaller the amino equivalent value, the higher the proportion of amino or ammonium groups in the molecule.

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

[0014] The amino-modified silicone may, for example, be a compound represented by the following general formula (1).

[0015] [ka] (In formula (1), R 1 represents an alkyl group or an aryl group having 1 to 20 carbon atoms. 2 R is a group represented by the following general formula (2). 3 is R 1 , R 2 -OR 9 (R 9is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. p is 5≦p≦10000, and q is 0≦q≦1000. However, when q=0, R 3 At least one of the repeating units p and q is a group represented by the following general formula (2). The order of the repeating units bounded by p and q is not limited, and the bonding pattern may be alternating, block, or random.

[0016] In formula (1), R 1 represents an alkyl group or an aryl group having 1 to 20 carbon atoms. 1 is preferably an alkyl group or aryl 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. 2 R is a group represented by the following general formula (2). 3 is R 1 , R 2 -OR 9 and preferably R 1 In addition, multiple R in formula (1) 9 may be the same or different. R 9 is 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. p is a number from 5 to 10,000, preferably 30 to 5,000, and more preferably 50 to 2,000. q is a number from 0 to 1,000, preferably 1 to 500, and more preferably 2 to 100.

[0017] [ka]

[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 , R7 and R 8 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group, preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and more preferably a hydrogen atom. r is a number of 0 to 6, preferably 0 to 3, and more preferably 0 to 1.

[0019] [(Poly)oxyalkylene derivative (B)] The treating agent of the present invention contains a (poly)oxyalkylene derivative (B) (hereinafter, sometimes referred to as derivative (B)). The derivative (B) is not particularly limited as long as it is a compound having a (poly)oxyalkylene group. Examples of the derivative (B) include polyoxyalkylene linear alkyl ethers, polyoxyalkylene branched alkyl ethers, polyoxyalkylene secondary alkyl ethers, polyoxyethylene alkenyl ethers, alkylene oxide adducts of alkynediols, polyoxyalkylene alkylphenyl ethers, alkylene oxide adducts of bisphenols, polyoxyethylene polycyclic phenyl ethers, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan esters, polyoxyalkylene castor oil ethers, polyoxyalkylene hydrogenated castor oil ethers, polyoxyethylene polyoxypropylene polymers, and polyoxyalkylene alkylamino ethers. Among these, from the viewpoint of achieving the effects of the present application, easily satisfying Conditions 1 and 2, and easily satisfying the ratio (Z2 / Z1) of 5 to 13, it is preferable to include at least one selected from polyoxyalkylene linear alkyl ethers, polyoxyalkylene branched alkyl ethers, polyoxyalkylene secondary alkyl ethers, alkylene oxide adducts of alkynediols, polyoxyalkylene alkylphenyl ethers, alkylene oxide adducts of bisphenols, and polyoxyethylene polycyclic phenyl ethers, and it is more preferable to include a compound having a structure in which an alkylene oxide having 2 to 4 carbon atoms is added to at least one selected from alcohols having 6 to 20 carbon atoms and 1 to 3 hydroxy groups and phenols having 6 to 20 carbon atoms and 1 to 3 hydroxy groups.

[0020] Examples of the alcohols having 6 to 20 carbon atoms and 1 to 3 hydroxy groups and the phenols having 6 to 20 carbon atoms and 1 to 3 hydroxy groups include linear alcohols such as hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol; branched alcohols such as 2-ethylhexyl alcohol, isodecyl alcohol, isotridecyl alcohol, and isooctadecyl alcohol; secondary alcohols such as secondary dodecyl alcohol, secondary tridecyl alcohol, and secondary tetradecyl alcohol; alkenyl alcohols such as octadecenyl alcohol; alkynediols such as alkynediols having 12 to 18 carbon atoms; alkylphenols such as nonylphenol; bisphenols such as bisphenol A and bisphenol F; polycyclic phenols such as styrenated phenol, distyrenated phenol, and tristyrenated phenol; sorbitan esters such as sorbitan fatty acid esters; and polyoxyalkylenes such as polyethylene glycol and polypropylene glycol. In terms of achieving the effects of the present invention, the alcohol having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups and the phenol having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups preferably includes at least one selected from hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, isodecyl alcohol, isotridecyl alcohol, isooctadecyl alcohol, secondary dodecyl alcohol, secondary tridecyl alcohol, secondary tetradecyl alcohol, nonylphenol, bisphenol A, bisphenol F, styrenated phenol, distyrenated phenol, and tristyrenated phenol. Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, butylene oxide, etc. As the alkylene oxide, at least one selected from ethylene oxide and propylene oxide is preferred, in that the effects of the present invention are exhibited, conditions 1 and 2 are likely to be satisfied, and (Z2 / Z1) is likely to satisfy 5 to 13. The derivative (B) may contain one or more kinds, and it is more preferable to contain two or more kinds in terms of excellent emulsifiability.

[0021] The number of moles of alkylene oxide added in the polyoxyalkylene chain of the (poly)oxyalkylene derivative (B) is preferably 1 to 25 moles, from the viewpoints of achieving the effects of the present invention, easily satisfying conditions 1 and 2, and easily satisfying (Z2 / Z1) of 5 to 13. The upper limit of the number of moles added is more preferably 20 moles, even more preferably 18 moles, and particularly preferably 15 moles. On the other hand, the lower limit of the number of moles added is more preferably 2 moles, even more preferably 3 moles. Also, for example, 2 to 18 moles is more preferable, and 3 to 15 moles is even more preferable.

[0022] [Brønsted acid compound (C)] The treating agent of the present invention preferably contains a Brønsted acid compound (C) because it is more likely to satisfy conditions 1 and 2. The Brønsted acid compound (C) refers to a proton donor, and examples thereof include organic carboxylic acid compounds, inorganic acids, organic sulfonic acid compounds, organic phosphate ester compounds, organic sulfate ester compounds, and organic phosphonic acid compounds.

[0023] 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.

[0024] 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.

[0025] 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 polyoxypolypropylene groups.

[0026] 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.

[0027] The aromatic monocarboxylic acids include benzoic acid, cinnamic acid, naphthoic acid, toluic acid, and derivatives thereof.

[0028] Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and derivatives thereof.

[0029] 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.

[0030] Inorganic acids are acids containing non-metallic atoms, such as sulfuric acid, nitric acid, phosphoric acid, and hydrochloric acid.

[0031] 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.

[0032] 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.

[0033] Examples of the organic sulfate compound include alkyl sulfate, polyoxyalkylene alkyl sulfate, alkylphenyl sulfate, and polyoxyalkylene alkylphenyl sulfate.

[0034] Examples of the organic phosphonic acid compound include alkyl phosphonic acid, aromatic phosphonic acid, and polyoxyalkylene alkyl ether phosphonic acid.

[0035] The pKa of the Bronsted acid compound (C) 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 caused by the amino groups of the amino-modified silicone.

[0036] The Bronsted acid compound (C) 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, in that it is easy to satisfy conditions 1 and 2. One or more Bronsted acid compounds (C) may be used.

[0037] [Treatment agent for carbon fiber precursor] The treating agent for carbon fiber precursors of the present invention contains the above-mentioned silicone (A) and (poly)oxyalkylene derivative (B), and satisfies the following conditions 1 and 2. Condition 1: When the nonvolatile content is dispersed in water at 1% by weight, the absorbance (X1) at 600 nm is 0.07 to 1.0. Condition 2: When the nonvolatile content is dispersed in water at 5% by weight, the absorbance (X2) at 900 nm is 0.05 to 0.8. The non-volatile content concentration in this invention is determined by spreading 2.0 to 3.0 g of the treatment agent evenly on an aluminum sheet (φ110 mm), drying it at 110°C under infrared lamp irradiation, 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 this 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.

[0038] The reason why the treatment agent for carbon fiber precursors of the present invention contains silicone (A) and derivative (B) and satisfies conditions 1 and 2 above and, therefore, can reduce fuzz and thread breakage when producing carbon fiber precursors and carbon fibers even when using a treatment agent that has been stored for a long period after preparation, is not particularly limited, but is thought to be that the ability to maintain an aqueous dispersion state that shows absorbance within a specific range at each of two levels of non-volatile content, 1% by weight and 5% by weight, allows stable adsorption to the fiber surface to be maintained even against local changes in the concentration of the treatment agent that occur when the components in the treatment agent are adsorbed to the carbon fiber precursor in the oil bath, and the treatment agent can be uniformly adsorbed even to the surface of single fibers inside the fiber bundle, making it less likely that changes will occur in the degree of adsorption of the treatment agent components to the carbon fiber precursor even when the treatment agent has been stored for a long period of time.

[0039] The absorbance (X1) described in the condition 1 and the absorbance (X2) described in the condition 2 were measured with an ultraviolet-visible-near-infrared spectrophotometer after diluting the carbon fiber precursor treatment agent with water as necessary to form an aqueous dispersion with a non-volatile content of 1% by weight or 5% by weight, and were measured according to the method described in the examples.

[0040] The absorbance (X1) described in the condition 1 is 0.07 to 1.0. If the absorbance (X1) is less than 0.07, the treatment agent penetrates into the interior of the single fiber, resulting in increased fuzz and thread breakage. If the absorbance (X1) is more than 1.0, the adsorption of the treatment agent to the carbon fiber precursor after long-term storage is impaired, resulting in increased fuzz and thread breakage. The lower limit of the absorbance (X1) is preferably 0.08, more preferably 0.1, and even more preferably 0.2. On the other hand, the upper limit of the absorbance (X1) is preferably 0.9, more preferably 0.8, and even more preferably 0.7. For example, the absorbance is preferably 0.08 to 0.9, more preferably 0.1 to 0.7, and even more preferably 0.2 to 0.7.

[0041] The absorbance (X2) described in the condition 2 is 0.05 to 0.8. If the absorbance (X2) is less than 0.05, the treatment agent penetrates into the interior of the single fiber, resulting in increased fuzz and thread breakage. If the absorbance (X2) is more than 0.8, the adsorption of the treatment agent to the carbon fiber precursor after long-term storage is impaired, resulting in increased fuzz and thread breakage. The lower limit of the absorbance (X2) is preferably 0.06, more preferably 0.08, and even more preferably 0.2. On the other hand, the upper limit of the absorbance (X2) is preferably 0.7, more preferably 0.6, and even more preferably 0.55. For example, 0.06 to 0.7 is more preferable, 0.08 to 0.6 is even more preferable, and 0.2 to 0.55 is particularly preferable.

[0042] The non-volatile content of the treatment agent of the present invention 1In a spectrum measured by H-NMR, the ratio (Y2 / Y1) of the area of ​​the peak (Y2) in the range of -0.3 to 0.3 ppm to the area of ​​the peak (Y1) in the range of 0.4 to 0.7 ppm indicates the proportion of modified groups in the silicone. A ratio of 100 to 1200 is considered to indicate excellent thermal stability of the silicone, making it less likely to generate tar during the flame-proofing process and preventing damage to the fibers due to contact with tar. The upper limit of the peak area ratio (Y2 / Y1) is more preferably 1100, even more preferably 1000, and particularly preferably 900. Meanwhile, the lower limit of the peak area ratio (Y2 / Y1) is more preferably 200, even more preferably 300, and particularly preferably 400. Furthermore, for example, a ratio of 200 to 1100 is more preferable, even more preferably 300 to 1000, and particularly preferably 400 to 900 is also preferable.

[0043] The non-volatile content of the treatment agent of the present invention 1 In a spectrum measured by H-NMR, the ratio (Z2 / Z1) of the area of ​​the peak (Z2) in the range of -0.3 to 0.3 ppm to the area of ​​the peak (Z1) in the range of 3.5 to 4.0 ppm indicates the ratio of the silicone main chain to the (poly)oxyalkylene group of the (poly)oxyalkylene derivative. A ratio of 5 to 13 is preferred from the perspective of emulsification, as it is believed to contain an appropriate amount of (poly)oxyalkylene groups for emulsifying the silicone. The upper limit of the peak area ratio (Z2 / Z1) is more preferably 12, even more preferably 11, and particularly preferably 10. Meanwhile, the lower limit of the peak area ratio (Z2 / Z1) is more preferably 5.5, even more preferably 6.0, and particularly preferably 6.5. Furthermore, for example, a range of 5.5 to 12 is more preferred, 6.0 to 11 is more preferred, and 6.5 to 10 is particularly preferred.

[0044] When the treatment agent of the present invention is dispersed in water with a nonvolatile content of 1% by weight, the surface tension is preferably 20 to 35 mN / m in terms of uniform adhesion of the treatment agent. The upper limit of the surface tension is more preferably 34 mN / m, even more preferably 33 mN / m, and particularly preferably 32 mN / m. Meanwhile, the lower limit of the surface tension is more preferably 22 mN / m, even more preferably 23 mN / m, and particularly preferably 24 mN / m. Furthermore, for example, 22 to 34 mN / m is more preferable, even more preferably 23 to 33 mN / m, and particularly preferably 24 to 32 mN / m.

[0045] The proportion of silicone (A) in the non-volatile content of the treating agent of the present invention is preferably 50 to 95% by weight, since this tends to satisfy conditions 1 and 2 and tends to make (Z2 / Z1) 5 to 13. The upper limit of this proportion is more preferably 90% by weight, even more preferably 87% by weight, and particularly preferably 85% by weight. Meanwhile, the lower limit of this proportion is more preferably 55% by weight, even more preferably 65% ​​by weight, and particularly preferably 75% by weight. Furthermore, for example, 55 to 90% by weight is more preferable, 65 to 87% by weight is even more preferable, and 75 to 85% by weight is particularly preferable.

[0046] The proportion of derivative (B) in the non-volatile content of the treatment agent of the present invention is preferably 5 to 25% by weight, since this tends to satisfy conditions 1 and 2 and tends to make (Z2 / Z1) 5 to 13. The upper limit of this proportion is more preferably 23% by weight, even more preferably 20% by weight, and particularly preferably 18% by weight. Meanwhile, the lower limit of this proportion is more preferably 6% by weight, even more preferably 7% by weight, and particularly preferably 8% by weight. Furthermore, for example, 6 to 23% by weight is more preferable, 7 to 20% by weight is even more preferable, and 8 to 18% by weight is particularly preferable.

[0047] The ratio of derivative (B) to 100 parts by weight of silicone (A) is preferably 5 to 35 parts by weight, since this makes it easier to satisfy conditions 1 and 2 and to have a (Z2 / Z1) ratio of 5 to 13. The upper limit of this ratio is more preferably 30 parts by weight, even more preferably 25 parts by weight, and particularly preferably 23 parts by weight. On the other hand, the lower limit of this weight ratio is more preferably 6 parts by weight, even more preferably 8 parts by weight, and particularly preferably 1 part by weight. Furthermore, for example, 6 to 30 parts by weight is more preferable, 8 to 25 parts by weight is even more preferable, and 1 to 23 parts by weight is particularly preferable.

[0048] When the treatment agent of the present invention further contains a Brønsted acid compound (C), the proportion of the Brønsted acid compound (C) in the non-volatile content of the treatment agent of the present invention is preferably 0.05 to 10% by weight, since this makes it easier to satisfy conditions 1 and 2. The upper limit of this weight proportion is more preferably 8.5% by weight, even more preferably 7% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of this weight proportion is more preferably 0.65% by weight, even more preferably 0.80% by weight, and particularly preferably 1% by weight. Furthermore, for example, 0.80 to 7% by weight is more preferable, and 1 to 5% by weight is even more preferable.

[0049] When the treatment agent of the present invention further contains a Brønsted acid compound (C), the weight ratio of the Brønsted acid compound (C) to the silicone (A) ((C) / (A)) is preferably 0.005 to 0.075, since this makes it easier to satisfy conditions 1 and 2. The upper limit of this ratio is more preferably 0.070, even more preferably 0.065, particularly preferably 0.060, and most preferably 0.055. On the other hand, the lower limit of this ratio is more preferably 0.0065, even more preferably 0.008, particularly preferably 0.01, and most preferably 0.012. Furthermore, for example, the ratio is more preferably 0.010 to 0.060, and even more preferably 0.012 to 0.055.

[0050] [Other ingredients (D)] The treatment agent of the present invention preferably further contains another nonionic surfactant as other component (D) in order to enhance emulsifiability. The other nonionic surfactant refers to a nonionic surfactant other than the derivative (B). Other nonionic surfactants 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 2000 or less, more preferably 200 to 1800, more preferably 300 to 1500, and even more preferably 500 to 1000. One or more types of the other nonionic surfactant may be used.

[0051] 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% from the viewpoint 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.

[0052] [Other surfactants] The treatment agent of the present invention may contain surfactants other than the derivative (B), the Bronsted acid compound (C), 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 from anionic surfactants, cationic surfactants, and amphoteric surfactants and used. One type of surfactant may be used, or two or more types may be used in combination.

[0053] 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- Acylamidoalkyl quaternary ammonium salts such as stearoylamidopropyl ammonium nitrate, lanolin fatty acid amidopropylethyl dimethylammonium ethosulfate, and lauroylamidoethyl methyldiethylammonium methosulfate; alkylisoquinolinium salts such as laurylisoquinolinium chloride; benzalkonium salts such as lauryldimethylbenzylammonium chloride and stearyldimethylbenzylammonium 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 ester chloride; primary amine salts such as laurylamine chloride, stearylamine bromide, hardened beef tallow alkylamine chloride, and rosinamine acetate;Examples of the secondary amine salts include cetylmethylamine sulfate, laurylmethylamine chloride, dilaurylamine acetate, stearylethylamine bromide, laurylpropylamine acetate, dioctylamine chloride, and octadecylethylamine hydroxide; tertiary amine salts include 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.

[0054] 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.

[0055] [Other ingredients] The treating agent for carbon fiber precursors of the present invention may contain other components in addition to the above-mentioned components, provided that the effects of the present invention are not impaired. Examples of such 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.

[0056] 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 contained as trace components of the silicone (A). 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 silicone (A).

[0057] The treating agent for carbon fiber precursors of the present invention is preferably in a state in which the silicone (A) and derivative (B), and, if necessary, the Brønsted acid compound (C) and other components (D) are dissolved, solubilized, emulsified, or dispersed in water. There are no particular limitations on the weight percentage of water and the weight percentage of nonvolatile matter in the entire carbon fiber precursor treatment agent. For example, these may be appropriately determined taking into consideration factors such as 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 percentage (concentration) of nonvolatile matter in the entire carbon fiber precursor treatment agent is preferably 0.01 to 99.9 wt %, more preferably 0.5 to 90 wt %, and particularly preferably 1 to 50 wt %.

[0058] 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 cause phase inversion emulsification. Alternatively, a method in which some components are emulsified and then the remaining components are dissolved and dispersed may be used. Although there are no particular limitations on the method for producing the treatment agent for carbon fiber precursors of the present invention, using a homomixer during emulsification is preferred because it is easier to satisfy conditions 1 and 2, and emulsification is more preferably carried out at a peripheral tip speed of 15 m / s or higher. On the other hand, when using a stirring impeller during emulsification, stirring is preferably carried out at a blade tip speed of 2.0 m / s or higher, and more preferably at a blade tip speed of 2.5 m / s or higher, because it is easier to satisfy conditions 1 and 2. Furthermore, the proportion of the (poly)oxyalkylene derivative (B) in the nonvolatile content during emulsification is preferably 5% by weight to 25% by weight, because it is easier to satisfy conditions 1 and 2, and the temperature during emulsification is preferably 70°C or higher, and more preferably 75°C or higher, because it is easier to satisfy conditions 1 and 2.

[0059] The treating agent for carbon fiber precursors of the present invention can be suitably used as a treating agent for carbon fiber precursors for producing carbon fibers.

[0060] [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 treating agent for carbon fiber precursors to a raw material carbon fiber precursor of the carbon fiber precursor, and spinning the resultant into a fiber. The method for producing a carbon fiber precursor of the present invention includes a spinning step of adhering the above-mentioned treating agent for carbon fiber precursors to a raw material carbon fiber precursor of the carbon fiber precursor, and spinning the resultant into a fiber. The method for producing a carbon fiber of the present invention includes a flame-retardant treatment step of converting the carbon fiber precursor having the above-mentioned treatment agent for a carbon fiber precursor attached thereto into a flame-retardant fiber, and a carbonization treatment step of further carbonizing the flame-retardant fiber. The flame-resistant treatment step is preferably a flame-resistant treatment step in which a carbon fiber precursor is converted into a flame-resistant fiber in an oxidizing atmosphere at 200 to 300°C, and the carbonization treatment step is preferably a step in which the flame-resistant fiber is further carbonized 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.

[0061] The spinning step is a step of spinning the carbon fiber precursor by adhering a treatment agent for carbon fiber precursors to a raw material carbon fiber precursor of the carbon fiber precursor, and preferably includes an adhering treatment step and a drawing step. The adhesion treatment step is a step of adhering a treatment agent for a carbon fiber precursor after spinning the raw carbon fiber precursor of the carbon fiber precursor. That is, in the adhesion treatment step, the treatment agent for a carbon fiber precursor is adhered to the raw carbon fiber precursor of the carbon fiber precursor. When the raw carbon fiber precursor of the carbon fiber precursor is stretched immediately after spinning, the high-magnification stretching after the adhesion treatment step is particularly called the "stretching step." The stretching step may be a wet heat stretching method using high-temperature steam, or a dry heat stretching method using a heated roller. The stretching ratio in the stretching step is preferably 2 to 20 times the total stretching ratio of the raw carbon fiber precursor immediately after spinning.

[0062] The carbon fiber precursor is preferably composed of acrylic fibers, and more preferably composed of acrylic fibers whose main component is polyacrylonitrile obtained by copolymerizing at least 95 mol% or more of acrylonitrile with 5 mol% or less of a flame retardant-promoting component. A vinyl group-containing compound copolymerizable with acrylonitrile is preferably 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 terms 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 terms of the balance between performance and production costs.

[0063] The treating agent for carbon fiber precursors may be applied to the raw material carbon fiber precursor of the carbon fiber 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, a spraying method, or the like.

[0064] 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.

[0065] The flame-resistant treatment step is a step of converting a carbon fiber precursor having a treatment agent for carbon fiber precursors attached thereto into a flame-resistant fiber in an oxidizing atmosphere at, for example, 200 to 300°C. The oxidizing atmosphere may usually 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.

[0066] 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, a preliminary carbonization step (first carbonization step) is preferably performed by heat-treating the flame-resistant fiber 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, as compared to the first carbonization step, in a second carbonization step, thereby carbonizing the flame-resistant fiber. The heat treatment temperature in the second carbonization step is preferably controlled by applying a temperature gradient and setting the maximum temperature to 1000°C or higher (preferably 1000 to 2000°C). This maximum temperature is appropriately selected and determined depending on the desired properties (tensile strength, elastic modulus, etc.) of the carbon fiber.

[0067] 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.

[0068] 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. [Example]

[0069] 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.

[0070] <Treatment agent application rate> The carbon fiber precursor after the treatment agent was 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 the silicon content was determined by colorimetric quantification (wavelength 815 nm) of silicomolybdenum blue. The silicon content determined here and the silicon content in the treatment agent previously determined by the same method were used to calculate the application rate (wt%) of the carbon fiber precursor treatment agent.

[0071] <Number of fluffs in carbon fiber bundles> Carbon fibers were produced using treatment agents for carbon fiber precursors with a nonvolatile content of 30% by weight that had been stored under the following two conditions, and the number of fluffs was measured using the method described below. Storage condition 1: Store at room temperature for 1 month Storage condition 2: Store 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 of fluffs 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 (pieces / m) present on the surface of the carbon fiber bundle was calculated from the measured length of the carbon fiber bundle, and ⊚ and ◯ were evaluated as pass. ⊚: The number of fluffs is less than 3 / m, and the fluff is particularly good. Good: The number of fluffs is 3 or more and less than 10 / m, and the fluff is low and good. ×: The number of fluffs is 10 or more per meter, and there is a lot of fluff, making it poor quality.

[0072] <Firing operation (bundling)> When carbon fibers were produced using a treatment agent for carbon fiber precursors with a non-volatile content of 30% by weight that had been stored under the following two conditions, the state of the flame-resistant fiber bundle immediately after passing through the flame-resistant furnace in the firing process of the carbon fiber precursor was evaluated according to the following evaluation criteria, with ◎ and ◯ being considered as passing. Storage condition 1: Store at room temperature for 1 month Storage condition 2: Store at room temperature for 12 months ◎: The fiber bundle width does not expand, there is no interference with adjacent fiber bundles, and the operability is particularly good. ◯: The fiber bundle width expands slightly, but there is no interference with adjacent fiber bundles, and workability is good. ×: The width of the fiber bundle increases, causing interference with adjacent fiber bundles, and fluffing may occur, resulting in poor workability.

[0073] <Absorbance measurement> The pure water was transferred to a polystyrene cell with a 12.5 mm square and an optical path length of 10 mm, and the absorbance of the pure water was measured at 20°C using a UV-visible-near infrared spectrophotometer (V-750 manufactured by JASCO Corporation) at a specified wavelength. The carbon fiber precursor treatment agent was diluted with water to prepare an aqueous dispersion with a nonvolatile content of 1 wt% or 5 wt%. The diluted solution was used as a sample. The sample was transferred to the same polystyrene cell as the pure water, and the absorbance of the sample at 20°C was measured using a UV-Vis-NIR spectrophotometer (JASCO V-750) at a specified wavelength. The absorbance of the sample was calculated by subtracting the absorbance of pure water at the same wavelength from the absorbance. For the sample with a nonvolatile content of 1 wt%, the absorbance at a wavelength of 600 nm (X1) was measured, and for the sample with a nonvolatile content of 5 wt%, the absorbance at a wavelength of 900 nm (X2) was measured.

[0074] < 1 H-NMR Measurement 1 g of a carbon fiber precursor treatment agent with a nonvolatile content of 30 wt% was collected and placed in a beaker to dry off the water. Then, 3 mL of chloroform-d (for NMR) was added to dissolve the solution uniformly, and the solution was poured into an NMR sample tube until the measurement solution reached a depth of 4 to 5 cm. 1 The spectrum was obtained by measuring with a 1H-NMR (JEOL JNM-ECZ400R) at room temperature with 16 scans. In the obtained spectrum, the ratio (Y2 / Y1) of the area of ​​the peak (Y2) in the range of -0.3 to 0.3 ppm to the area (Y1) of the peak in the range of 0.4 to 0.7 ppm, and the ratio (Z2 / Z1) of the area of ​​the peak (Z2) in the range of -0.3 to 0.3 ppm to the area (Z1) of the peak in the range of 3.5 to 4.0 ppm were calculated.

[0075] <Surface tension measurement> The carbon fiber precursor treatment agent was diluted with water to prepare a water dispersion with a nonvolatile content of 1% by weight. The surface tension of the prepared sample was measured using an automatic surface tensiometer (DY-500 manufactured by Kyowa Interface Science Co., Ltd.) at 25°C using a platinum plate by the Wilhelmy method.

[0076] Example 1 Amino-modified silicone A1, (poly)oxyalkylene derivatives B5, B6, and B7, and antioxidants D1 and D2 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 80 to 90°C (condition I), and emulsification was carried out by gradually adding water while stirring using a stirring blade at a blade tip speed of 3 m / s (condition A). Then, Brønsted acid compound C6, antistatic agent D3, and acetylene-based surfactant D4 were dissolved and dispersed to prepare a treatment agent for carbon fiber precursors with a nonvolatile concentration of 30 wt%. The weight percentage of silicone A1 in the nonvolatile content of the treatment agent was 80.8 wt%, the weight percentage of polyoxyalkylene derivative B5 was 3.7 wt%, the weight percentage of B6 was 2.5 wt%, the weight percentage of B7 was 2 wt%, the weight percentage of Bronsted acid compound C6 was 4.0 wt%, the weight percentage of antistatic agent D3 was 4 wt%, the total weight percentage of antioxidants D1 and D2 was 1 wt%, and the weight percentage of acetylene surfactant D4 was 2.0 wt%. The adjusted 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 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 flame-resistant treated 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.

[0077] [Examples 2 to 16, 22 to 29, Comparative Examples 1 to 6] A treating agent for carbon fiber precursors, a carbon fiber precursor, and a carbon fiber were prepared and evaluated in the same manner as in Example 1, except that the nonvolatile content composition, the temperature conditions during emulsification, and the stirring conditions during emulsification were changed as shown in Tables 1 to 3 and 5. The results of evaluating each property value are shown in Tables 1 to 3 and 5. The order of adding the Bronsted acid compound (C) and the other components (D) other than the antioxidant was the same as in Example 1.

[0078] [Examples 17, 18, 30 to 33] Regarding the nonvolatile composition, a treating agent for carbon fiber precursors, a carbon fiber precursor, and carbon fibers were prepared and evaluated in the same manner as in Example 1, except that B11 and B12 were not mixed during emulsification, but were mixed after emulsification, and the temperature conditions and stirring conditions during emulsification were changed as shown in Tables 2 and 3. The evaluation results for each property value are shown in Tables 2 and 3. The order of addition of the Bronsted acid compound (C) and other components (D) other than the antioxidant was the same as in Example 1.

[0079] Example 21 Regarding the nonvolatile composition, a treating agent for carbon fiber precursors, a carbon fiber precursor, and carbon fibers were prepared and evaluated in the same manner as in Example 1, except that B5 was not mixed during emulsification but was mixed after emulsification, and the temperature conditions and stirring conditions during emulsification were changed as shown in Table 2. The results of evaluating each property value are shown in Table 2. The order of adding the Bronsted acid compound (C) and other components (D) other than the antioxidant was the same as in Example 1.

[0080] Examples 34 to 36 Regarding the nonvolatile composition, a treating agent for carbon fiber precursors, a carbon fiber precursor, and carbon fibers were prepared and evaluated in the same manner as in Example 1, except that B14 was not mixed during emulsification but was mixed after emulsification, and the temperature conditions and stirring conditions during emulsification were changed as shown in Table 4. The results of evaluating each property value are shown in Table 4. The order of adding the Bronsted acid compound (C) and other components (D) other than the antioxidant was the same as in Example 1.

[0081] Example 37 Regarding the nonvolatile composition, a treating agent for carbon fiber precursors, a carbon fiber precursor, and a carbon fiber were prepared and evaluated in the same manner as in Example 1, except that B11, B12, and B14 were not mixed during emulsification, but B11, B12, and B14 were mixed after emulsification, and the temperature conditions and stirring conditions during emulsification were changed as shown in Table 4. The results of evaluating each property value are shown in Table 4. The order of adding the Bronsted acid compound (C) and other components (D) other than the antioxidant was the same as in Example 1.

[0082] Examples 38 to 44 Regarding the nonvolatile composition, a treating agent for carbon fiber precursors, a carbon fiber precursor, and a carbon fiber were prepared and evaluated in the same manner as in Example 1, except that the other components, alkyl esters (D6, D7, D8) and wax (D9), were added before emulsification, and the temperature conditions and stirring conditions during emulsification were changed as shown in Table 4. The results of evaluating each property value are shown in Table 4. The order of adding the Brønsted acid compound (C) and the other components, antistatic agent (D3) and acetylene surfactant (D4), was the same as in Example 1.

[0083] The temperature conditions and stirring conditions during emulsification shown in Tables 1 to 5 were as follows: (Temperature during emulsification) Condition I: 80-90℃ Condition II: 30~40℃ (stirring conditions) Condition A: Agitation was performed using an impeller at a tip speed of 3 m / s. Condition B: Stirring was performed using an impeller at a tip speed of 0.5 m / s. Condition C: Mixing was performed using a homomixer at a peripheral tip speed of 25 m / s.

[0084] The details of the nonvolatile composition in Tables 1 to 5 are as follows: In the tables, components with an * next to the number indicate that they were not mixed during emulsification, but were mixed after emulsification. <Silicone (A)> Amino-modified silicone A1: 25°C kinematic viscosity: 250mm 2 / s, amino equivalent: 7600g / mol, side chain diamine type Amino-modified silicone A2: 25°C kinematic viscosity: 3500mm 2 / s, amino equivalent: 2000g / mol, side chain diamine type Amino-modified silicone A3: 25°C kinematic viscosity: 1700mm 2 / s, amino equivalent: 3800g / mol, side chain monoamine type Amino-modified silicone A4: 25°C kinematic viscosity: 1300mm 2 / s, amino equivalent: 1700g / mol, side chain diamine type Amino-modified silicone A5: 25°C kinematic viscosity: 1500mm 2 / s, amino equivalent: 3800g / mol, side chain diamine type Amino-modified silicone A6: 25°C kinematic viscosity: 90mm 2 / s, amino equivalent: 3900g / mol, diamine type Amino-modified silicone A7: 25°C kinematic viscosity: 200mm 2 / s, amino equivalent: 4000g / mol Aminopolyether modified silicone A8: 25°C kinematic viscosity: 3300mm 2 / s, amino equivalent: 1800g / mol, side chain amino polyether type Amino-modified silicone A9: 25°C kinematic viscosity: 15,000 mm 2 / s, amino equivalent: 3600g / mol, diamine type Amino-modified silicone A10: 25°C kinematic viscosity: 9000mm 2 / s, amino equivalent: 9000g / mol, diamine type Amino-modified silicone A11: 25°C kinematic viscosity: 70mm 2 / s, amino equivalent: 350g / mol, diamine type Polyether modified silicone A12: 25°C kinematic viscosity: 130mm 2 / s, HLB=4, polyether type Amino-modified silicone A13: 25°C kinematic viscosity: 2500mm 2 / s, amino equivalent: 3600g / mol, side chain diamine type

[0085] <(Poly)oxyalkylene Derivative (B)> (Poly)oxyalkylene derivative B1: an alkyl ether having 12 carbon atoms and 3 moles of oxyethylene groups added (Poly)oxyalkylene derivative B2: an alkyl ether having 12 carbon atoms and 9 moles of oxyethylene groups added (Poly)oxyalkylene derivative B3: an alkyl ether having 18 carbon atoms and 13 moles of oxyethylene groups added (Poly)oxyalkylene derivative B4: tribenzyl phenyl ether to which 14 moles of oxyethylene groups have been added (Poly)oxyalkylene derivative B5: A secondary alkyl ether having 12 to 14 carbon atoms to which 5 moles of oxyethylene groups have been added. (Poly)oxyalkylene derivative B6: A secondary alkyl ether having 12 to 14 carbon atoms to which 9 moles of oxyethylene groups have been added. (Poly)oxyalkylene derivative B7: A secondary alkyl ether having 12 to 14 carbon atoms to which 12 moles of oxyethylene groups have been added. (Poly)oxyalkylene derivative B8: Polyoxyethylene polyoxypropylene butyl ether (PO / EO=50 / 50, weight average molecular weight 540) (Poly)oxyalkylene derivative B9: Branched decyl ether with 4 moles of oxyethylene groups added (Poly)oxyalkylene derivative B10: Nonylphenyl ether to which 5 moles of oxyethylene groups have been added (Poly)oxyalkylene derivative B11: Bisphenol A ether to which 10 moles of oxyethylene groups have been added (Poly)oxyalkylene derivative B12: Polyoxyethylene polyoxypropylene polyether (PO / EO=25 / 75, weight average molecular weight 12,000) (Poly)oxyalkylene derivative B13: A secondary alkyl ether having 12 to 14 carbon atoms to which 7 moles of oxyethylene groups have been added. (Poly)oxyalkylene Derivatives B14: Polymers of Polyoxyethylene Bisphenol A Ether, Adipic Acid, and Coconut Fatty Acids

[0086] <Brønsted acid compound (C)> Bronsted acid compound C1: acetic acid Bronsted acid compound C2: Phosphoric acid Bronsted acid compound C3: Benzoic acid Bronsted acid compound C4: Arginine Bronsted acid compound C5: Alkyl ether acetic acid having 12 carbon atoms and 4.5 moles of oxyethylene groups added Bronsted acid compound C6: Alkyl ether acetic acid having 12 carbon atoms and 10 moles of oxyethylene groups added Bronsted acid compound C7: Secondary alkyl ether phosphate ester with 12 to 15 carbon atoms and 6 moles of oxyethylene groups added Bronsted acid compound C8: Secondary alkyl ether phosphate ester with 12 to 15 carbon atoms and 9 moles of oxyethylene groups added Bronsted acid compound C9: Secondary alkyl ether phosphate ester with 11 to 15 carbon atoms and 12 moles of oxyethylene groups added

[0087] <Other ingredients (D)> Antioxidant D1: Triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate Antioxidant D2: Dioleyl thiodipropionate Antistatic agent D3: Ethylenebis(hydroxyethyl)octadecylammonium ethyl sulfate Acetylenic surfactant D4: Acetylenic surfactant Preservative D5: Isothiazolinone preservative (manufactured by Thor Japan Co., Ltd., trade name ACTICIDE (registered trademark) MV4) Alkyl ester D6: Triisodecyl trimellitate Alkyl ester D7: Sunflower oil Alkyl ester D8: Hexaester of dipentaerythritol and 3,5,5-trimethylhexanoic acid Wax D9: Paraffin wax (melting point 61°C)

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

[0091] [Table 4]

[0092] [Table 5]

[0093] As can be seen from Tables 1 to 5, the treatment agents for carbon fiber precursors in Examples 1 to 44 contain silicone (A) and a (poly)oxyalkylene derivative (B) and satisfy the following conditions 1 and 2. Therefore, even when using treatment agents that had been stored for a long period after preparation, fluffing and thread breakage could be reduced when producing carbon fiber precursors and carbon fibers. On the other hand, when condition 1 was not satisfied (Comparative Example 1), when condition 2 was not satisfied (Comparative Example 4), when conditions 1 and 2 were not satisfied (Comparative Examples 2, 3, 5, and 6), or when silicone (A) was not included (Comparative Example 7), and when a treatment agent that had been stored for a long period after preparation was used, fuzz and yarn breakage could not be reduced when carbon fiber precursors and carbon fibers were produced. [Industrial Applicability]

[0094] 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, comprising a silicone (A) and a (poly)oxyalkylene derivative (B), and satisfying the following conditions 1 and 2: Condition 1: When the nonvolatile content is dispersed in water at 1% by weight, the absorbance (X1) at 600 nm is 0.07 to 1.

0. Condition 2: When the nonvolatile content is dispersed in water at 5% by weight, the absorbance (X2) at 900 nm is 0.05 to 0.

8.

2. The non-volatile content of the treatment agent １ 2. The treatment agent for carbon fiber precursors according to claim 1, wherein in a spectrum measured by H-NMR, a ratio (Y2 / Y1) of an area (Y2) of a peak in a range of −0.3 to 0.3 ppm to an area (Y1) of a peak in a range of 0.4 to 0.7 ppm is 100 to 1,200.

3. The non-volatile content of the treatment agent １ 3. The treatment agent for carbon fiber precursors according to claim 1 or 2, wherein in a spectrum measured by H-NMR, a ratio (Z2 / Z1) of an area (Z2) of a peak in a range of −0.3 to 0.3 ppm to an area (Z1) of a peak in a range of 3.5 to 4.0 ppm is 5 to 13.

4. The treatment agent for carbon fiber precursors according to any one of claims 1 to 3, wherein the treatment agent has a surface tension of 20 to 35 mN / m when dispersed in water with a nonvolatile content of 1% by weight.

5. The treatment agent for carbon fiber precursors according to any one of claims 1 to 4, wherein a proportion of the silicone (A) in the non-volatile components of the treatment agent is 50% by weight to 95% by weight, and a proportion of the derivative (B) is 5% by weight to 25% by weight.

6. The treating agent for carbon fiber precursors according to any one of claims 1 to 5, further comprising a Bronsted acid compound (C).

7. The treatment agent for carbon fiber precursors according to any one of claims 1 to 6, wherein the derivative (B) comprises a compound having a structure in which an alkylene oxide having 2 to 4 carbon atoms is added to at least one selected from alcohols having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups and phenols having 6 to 20 carbon atoms and having 1 to 3 hydroxy groups.

8. A carbon fiber precursor obtained by adhering the treating agent for carbon fiber precursors according to any one of claims 1 to 7 to a raw material carbon fiber precursor of the carbon fiber precursor.

9. A method for producing a carbon fiber, comprising: a flame-resistant treatment step of converting the carbon fiber precursor according to claim 8 into a flame-resistant fiber; and a carbonization treatment step of further carbonizing the flame-resistant fiber.

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