Treatment agent for carbon fiber precursor and use thereof

Abstract

To provide a treatment agent for a carbon fiber precursor capable of suppressing deterioration of the carbon fiber precursor when the carbon fiber precursor produced by applying the treatment agent is stored for a long period of time, a carbon fiber precursor using the treatment agent, and a method for producing a carbon fiber using the treatment agent.SOLUTION: A treatment agent for a carbon fiber precursor according to the present invention contains a silicone compound (S) and an aromatic compound (C), wherein the silicone compound (S) contains an amino group-containing silicone (SA) and a polyether-containing silicone (SB), the aromatic compound (C) contains at least one selected from an oxyalkylene group-containing aromatic compound (C1) and an ester group-containing aromatic compound (C2), and the proportion of the silicone compound (S) in nonvolatile content is 65 weight% or less.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Carbon fibers are widely used in aerospace applications, sports applications, general industrial applications, etc. as reinforcing fibers for composite materials with plastics called matrix resins, taking advantage of their excellent mechanical properties. As a method for producing carbon fibers, first, a carbon fiber precursor is produced (this production process of the carbon fiber precursor may be 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 may hereinafter be referred to as a flame-resistant treatment process), and subsequently carbonized in an inert atmosphere at 300 to 2000°C (this process may hereinafter be referred to as a carbonization treatment process). This method is common (hereinafter, the flame-resistant treatment process and the carbonization treatment process may be collectively referred to as a firing process). In such a firing process, fusion occurs between single fibers, easily causing problems such as fuzz and yarn breakage, which has been an obstacle to improving productivity.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the carbon fiber precursor produced by applying such a treatment agent was stored for a long time, there was a problem of causing deterioration of the carbon fiber precursor over time. Therefore, when the carbon fiber precursor stored for a long time was fired to produce carbon fiber, there were problems such as the generation of fluff in the firing process and the decrease in the strength of the carbon fiber after firing. In view of such a conventional technical background, an object of the present invention is to provide a treatment agent for a carbon fiber precursor capable of suppressing the deterioration of the carbon fiber precursor when the carbon fiber precursor produced by applying a treatment agent is stored for a long time, a carbon fiber precursor using the treatment agent, and a method for producing carbon fiber using the treatment agent.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that a treatment agent for a carbon fiber precursor containing a specific silicone compound (S) and a specific aromatic compound (C) and having a proportion of the silicone compound (S) in the non-volatile matter of 65% by weight or less can suppress the deterioration of the carbon fiber precursor when the carbon fiber precursor produced by applying the treatment agent is stored for a long time.

[0007] That is, the treatment agent for a carbon fiber precursor of the present invention includes the following embodiments. <1> A treatment agent for a carbon fiber precursor, which contains a silicone compound (S) and an aromatic compound (C), the silicone compound (S) contains a silicone having an amino group (SA) and a silicone having a polyether group (SB), the aromatic compound (C) contains at least one selected from an aromatic compound having an oxyalkylene group (C1) and an aromatic compound having an ester group (C2), and the proportion of the silicone compound (S) in the non-volatile matter is 65% by weight or less. <2> The treating agent for a carbon fiber precursor according to <1>, wherein the aromatic compound (C) contains an aromatic compound (C1) having an oxyalkylene group. <3> The treating agent for a carbon fiber precursor according to <1> or <2>, wherein the aromatic compound (C) contains an aromatic compound having a bisphenol skeleton. <4> The treating agent for a carbon fiber precursor according to any one of <1> to <3>, wherein the acid value of the treating agent is 0.1 to 30 mgKOH / g. <5> The treating agent for a carbon fiber precursor according to any one of <1> to <4>, wherein the HLB of the silicone (SB) having a polyether group is 4 to 16. <6> The treating agent for a carbon fiber precursor according to any one of <1> to <5>, wherein the silicone (SB) having a polyether group contains a silicone in which the polyether group has an oxypropylene unit. <7> The treating agent for a carbon fiber precursor according to any one of <1> to <6>, wherein the proportion of the aromatic compound (C) in the non-volatile matter of the treating agent is 35 to 90% by weight. <8> The treating agent for a carbon fiber precursor according to any one of <1> to <7>, which contains an aliphatic compound (D) having an oxyalkylene group. <9> A carbon fiber precursor obtained by attaching the treating agent for a carbon fiber precursor according to any one of <1> to <8> to a raw material carbon fiber precursor of the carbon fiber precursor. <10> A method for producing carbon fiber, comprising a flame-resistant treatment step of converting the carbon fiber precursor according to <9> into a flame-resistant fiber, and a carbonization treatment step of carbonizing the flame-resistant fiber.

Advantages of the Invention

[0008] The treatment agent for carbon fiber precursors of the present invention can suppress the deterioration of carbon fiber precursors even when the carbon fiber precursors produced by applying the treatment agent are stored for a long period. According to the method for producing carbon fiber precursors using the treatment agent for carbon fiber precursors of the present invention and carbon fibers using the treatment agent, even when the carbon fiber precursors produced by applying the treatment agent are stored for a long period, the deterioration of the carbon fiber precursors can be suppressed, and high-quality carbon fibers can be obtained.

Embodiments for Carrying Out the Invention

[0009] Each component of the treatment agent for carbon fiber precursors of the present invention (hereinafter sometimes simply referred to as the treatment agent) will be described. 〔Silicone Compound (S)〕 The treatment agent of the present invention contains a silicone compound (S). The silicone compound (S) is not particularly limited as long as the main chain is an inorganic siloxane bond (-Si-O-Si-) and it has an organic group in the side chain, but it contains a silicone having an amino group (SA) and a silicone having a polyether group (SB) described later. The silicone compound (S) may contain other silicones other than the silicone having an amino group (SA) and the silicone having a polyether group (SB). Examples of other silicones include dimethyl silicone, epoxy-modified silicone, amide-modified silicone, alkyl-modified silicone, aralkyl-modified silicone, phenyl-modified silicone, silanol-modified silicone, carbinol-modified silicone, mercapto-modified silicone, etc. In terms of achieving the effects of the present application, it is preferably included at least one selected from dimethyl silicone, alkyl-modified silicone, phenyl-modified silicone, and aralkyl-modified silicone, and more preferably includes phenyl-modified silicone and aralkyl-modified silicone. These other silicones can be known ones.

[0010] 〔Silicone Having an Amino Group (SA)〕 The treatment agent of the present invention contains silicone having an amino group (SA). The silicone having an amino group (SA) is not particularly limited as long as the main chain is an inorganic siloxane bond (-Si-O-Si-) and it has an organic group having an amino group at the side chain and / or the terminal, and known silicones having an amino group can be appropriately employed. Examples of the silicone having an amino group (SA) include amino-modified silicone, amino polyether-modified silicone, etc. In terms of achieving the effects of the present application, it is more preferable to include amino-modified silicone. One or more kinds of the silicone having an amino group (SA) may be used. Note that the 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).

[0011] The kinematic viscosity of the silicone having an amino group (SA) at 25°C is preferably 50 to 20000 mm 2 / s in terms of uniform adhesion to fibers, suppression of scattering of the treatment agent, and imparting of fiber bundling property. The upper limit of the kinematic viscosity is more preferably 15000 mm 2 / s, still more preferably 12000 mm 2 / s, particularly preferably 10000 mm 2 / s. On the other hand, the lower limit of the kinematic viscosity is more preferably 100 mm 2 / s, still more preferably 150 mm 2 / s, particularly preferably 200 mm 2 / s. Also, for example, 100 to 15000 mm 2 / s is more preferable, and 150 to 10000 mm 2 / s is still more preferable.

[0012] The amino group (including an organic group having an amino group), which is a modifying group of silicone (SA) having an amino group, may be bonded to the side chain of the silicone as the main chain, may be bonded to the terminal, or may be bonded to both. However, from the viewpoint of fiber protection in the flame-retardant treatment process, it is preferable that it is bonded to the side chain (having an amino group in the side chain). Further, the amino group may be any of a monoamine type, a diamine type, and a polyamine type, and both may coexist in one molecule. However, from the viewpoint of uniformly applying the treatment agent to the inside of the fiber bundle in the flame-retardant treatment process and forming a film of the treatment agent to protect the fiber, the monoamine type or the diamine type is preferable, and the diamine type is more preferable.

[0013] From the viewpoint of preventing adhesion and fusion between fibers, the amino equivalent of silicone (SA) having an amino group is preferably 300 to 10,000 g / mol. The upper limit of the amino equivalent is more preferably 9500 g / mol, further preferably 9000 g / mol, and particularly preferably 8000 g / mol. On the other hand, the lower limit of the amino equivalent is more preferably 500 g / mol, further preferably 1000 g / mol, and particularly preferably 1500 g / mol. Further, for example, 500 to 9000 g / mol is more preferable, and 1000 to 8000 g / mol is further preferable. Here, the amino equivalent means the mass of the siloxane skeleton per one amino group or ammonium group. The notation unit g / mol is a value converted per 1 mol of amino group or ammonium group. Therefore, the smaller the value of the amino equivalent, the higher the ratio of the amino group or ammonium group in the molecule.

[0014] Silicone (SA) having an amino group may be used in combination with a plurality of silicones having different amino equivalents and kinematic viscosities (at 25°C). When using a silicone having two or more amino groups, the above amino equivalent means the amino equivalent of the entire silicone (SA) (mixture) having an amino group, and the kinematic viscosity at 25°C above means the kinematic viscosity of the entire silicone (A) (mixture) having an amino group.

[0015] Examples of the amino-modified silicone include compounds represented by the following general formula (1).

[0016] [Chemical formula] (In formula (1), R 1 represents an alkyl group or aryl group having 1 to 20 carbon atoms. R 2 is a group represented by the following general formula (2). R 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 satisfies 1 ≦ a ≦ 10000, and b satisfies 0 ≦ b ≦ 1000. However, when b = 0, at least one of R 3 is a group represented by the following general formula (2). The order of each repeating unit enclosed by a and b is not limited, and the bonding mode may be alternating, block, or random.)

[0017] In formula (1), R 1 represents an alkyl group or aryl group having 1 to 20 carbon atoms. R 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 still more preferably a methyl group. Note that the plurality of R 1 in formula (1) may be the same or different. R 2 is a group represented by the following general formula (2). R 3 is a group represented by R 1 , R 2 or -OR 9 , and is preferably R 1 . Note that the plurality of R 9 in formula (1) may be the same or different.) R 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 10000, preferably from 30 to 5000, and more preferably from 50 to 2000. b is a number from 0 to 1000, preferably from 1 to 500, and more preferably from 2 to 100.

[0018] [Chemical formula]

[0019] 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. R 5 , R 7 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. c is a number from 0 to 6, preferably from 0 to 3, and more preferably from 0 to 1.

[0020] [Silicone having a polyether group (SB)] The treatment agent of the present invention contains a silicone having a polyether group (SB). The silicone having a polyether group (SB) has an inorganic siloxane bond (-Si-O-Si-) in the main chain, and has 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 having an amino group (SA). As the silicone (SB) having a polyether group, known silicones having a polyether group can be appropriately employed. Examples of the silicone (SB) having a polyether group include ABn type polyether-modified silicone, side chain type polyether-modified silicone, both ends type polyether-modified silicone, alkyl polyether-modified silicone in which both a polyether group and an alkyl group are introduced into the side chain or the ends, a side chain type polyether-modified silicone in which the terminal portion of the polyether chain is blocked with an aliphatic compound or a fatty acid compound, a both ends type polyether-modified silicone in which the terminal portion of the polyether chain is blocked with an aliphatic compound or a fatty acid compound, and the like. The silicone (SB) having a polyether group may be used alone or in combination of two or more kinds.

[0021] Examples of the silicone (SB) having a polyether group to be used in the treating agent of the present invention include compounds represented by the following general formula (3).

[0022] [Chemical formula] (In formula (3), R 10 represents an alkyl group or an aryl group having 1 to 20 carbon atoms. R 11 is a group represented by the following general formula (4). R 12 is R 10 , R 11 or -OR 15 (R 15 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). d satisfies 1 ≦ d ≦ 10000, and e is an integer satisfying 0 ≦ e ≦ 1000. However, when e = 0, at least one of R 12 is a group represented by the following general formula (4). The order of each repeating unit enclosed by d and e is not limited, and the bonding mode may be alternating, block, or random.)

[0023] In formula (3), R 10 represents an alkyl group or an aryl group having 1 to 20 carbon atoms. R 10is preferably an alkyl group or an aryl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably a methyl group. In the formula (3), a plurality of R 10 may be the same or different. R 12 is a group represented by R 10 , R 11 or -OR 15 , and is preferably R 1 . In the formula (3), a plurality of R 12 may be the same or different. R 15 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 still more preferably a hydrogen atom or a methyl group. d is an integer satisfying 1 ≦ d ≦ 10000, preferably 30 to 5000, and still more preferably 50 to 2000. e is an integer satisfying 0 ≦ e ≦ 1000, preferably 1 to 500, and still more preferably 2 to 100.

[0024] [Chemical formula] (In the formula (4), R 13 represents an alkylene group having 1 to 20 carbon atoms. R 14 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, or an acyl group having 2 to 8 carbon atoms. The alkyl group and the alkenyl group may be composed of either a linear or a branched structure. f and g are integers satisfying 1 ≦ f + g ≦ 200, f ≧ 0, and g ≧ 0. The order of each repeating unit enclosed by f and g is not limited, and the bonding pattern may be alternating, block, or random.)

[0025] In the formula (4), R 13 represents an alkylene group having 1 to 20 carbon atoms, preferably an alkylene group having 1 to 10 carbon atoms, and more preferably an alkylene group having 1 to 6 carbon atoms. R 14represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 1 to 30 carbon atoms, or an acyl group having 2 to 8 carbon atoms. Among them, an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 1 to 30 carbon atoms is preferred, and an alkyl group having 1 to 30 carbon atoms is more preferred. f and g are integers satisfying 1 ≦ f + g ≦ 200, f ≧ 0, and g ≧ 0. From the viewpoint of permeability into the fiber bundle, g is preferably 1 or more. The upper limit value of g is preferably 180, more preferably 150, and even more preferably 120. On the other hand, the lower limit value of g is more preferably 5, even more preferably 10, and particularly preferably 15. Also, for example, 10 to 150 is preferred, and 15 to 150 is more preferred.

[0026] The proportion of the total weight of the oxypropylene (hereinafter sometimes referred to as PO) unit and the oxyethylene (hereinafter sometimes referred to as EO) unit in the weight of the silicone (SB) having a polyether group is preferably 5 to 95% by weight from the viewpoints of permeability into the fiber bundle and stability of the treatment agent in an aqueous system. The upper limit of the proportion is more preferably 90% by weight, even more preferably 85% by weight, and particularly preferably 80% by weight. On the other hand, the lower limit of the proportion is more preferably 10% by weight, even more preferably 15% by weight, and particularly preferably 20% by weight. Also, for example, 10 to 95% by weight is more preferred, 15 to 95% by weight is even more preferred, and 20 to 90% by weight is particularly preferred.

[0027] The weight ratio (EO / PO) of the EO unit to the PO unit contained in the silicone (SB) having a polyether group is preferably 0.05 to 95 from the viewpoint of permeability into the fiber bundle. The upper limit of the ratio is more preferably 75, even more preferably 50, and particularly preferably 20. On the other hand, the lower limit of the ratio is more preferably 0.1, even more preferably 0.3, and particularly preferably 1.0. Also, for example, 0.1 to 50 is more preferred, and 0.1 to 20 is even more preferred. Here, the total ratio of PO units and EO units in the silicone (SB) having a polyether group, and the weight ratio of EO units to PO units (EO / PO) in the silicone (SB) having a polyether group mean the total weight ratio and weight ratio of all PO units and EO units contained in the silicone (SB) having a polyether group. When the silicone (SB) having a polyether group is 1 It refers to the value calculated from the weight ratio of PO units and EO units to the weight of the silicone (SB) having a polyether group calculated from the peak area when measured by H-NMR.

[0028] The value of HLB (Hydrophile-Lipophile Balance) represented by the hydrophilic-lipophilic balance of the silicone (SB) having a polyether group is not particularly limited, but is preferably 4 to 16 from the viewpoint of the stability of the treating agent in an aqueous system. The upper limit of the HLB is more preferably 15, further preferably 14, and particularly preferably 12. On the other hand, the lower limit of the HLB is more preferably 6, further preferably 7, and particularly preferably 8. Also, for example, 7 to 16 is more preferable, and 7 to 14 is further preferable. In addition, the HLB in the present invention is a value obtained by the following formula from the cloudiness number A measured as follows. HLB = cloudiness number A × 0.89 + 1.11 <Method for measuring the cloudiness number A> The cloudiness number A is measured as follows according to the known method "Surfactant Handbook, pages 324 to 325 (published by Sangyo Tosho Co., Ltd. on July 5, 1960)". Weigh 2.5 g of the silicone having an anhydrous polyether group, add 98% ethanol, and make the volume constant to 25 ml (using a 25 ml volumetric flask). Next, take 5 ml of this with a 5 ml whole pipette, put it into a 50 ml beaker, keep the temperature at 25 °C, stir (using a magnetic stirrer), and measure it using a 25 ml burette with a 2% aqueous phenol solution. The point at which the liquid becomes turbid is taken as the end point, and the ml number of the 2% aqueous phenol solution required for this titration is taken as the cloudiness number A.

[0029] The kinematic viscosity at 25°C of the silicone (SB) having a polyether group is 10 to 10,000 mm 2 / s, which is preferable in terms of the permeability into the fiber bundle. The upper limit of the kinematic viscosity is more preferably 8,000 mm 2 / s, even more preferably 7,000 mm 2 / s, particularly preferably 5,000 mm 2 / s. On the other hand, the lower limit of the kinematic viscosity is more preferably 50 mm 2 / s, even more preferably 100 mm 2 / s, particularly preferably 150 mm 2 / s. Further, for example, 50 to 5,000 mm 2 / s is more preferable, and 100 to 5,000 mm 2 / s is even more preferable.

[0030] Silicones (SB) having polyether groups may be used in combination with silicones having a plurality of polyether groups with different HLB values and kinematic viscosities (at 25°C). When using silicones having two or more polyether groups, the above HLB means the HLB of the entire silicone (SB) having a polyether group (mixture), and the kinematic viscosity at 25°C described above means the kinematic viscosity of the entire silicone (SB) having a polyether group (mixture).

[0031] 〔Aromatic compound (C)〕 The treating agent of the present invention contains an aromatic compound (C). The aromatic compound (C) is not particularly limited as long as it is a compound having an aromatic ring. For example, aromatic compounds (C1) having an oxyalkylene group, aromatic compounds (C2) having an ester group, etc. may be mentioned. The aromatic compound (C) contains at least one selected from aromatic compounds (C1) having an oxyalkylene group and aromatic compounds (C2) having an ester group, and it is preferable to contain an aromatic compound (C1) having an oxyalkylene group in terms of the stability of the treating agent in an aqueous system. The aromatic compound (C) preferably contains an aromatic compound having a bisphenol skeleton in terms of improving the aggregability during flame resistance. As the aromatic compound having a bisphenol skeleton, an aromatic compound having a bisphenol skeleton and an oxyalkylene group, and an aromatic compound having a bisphenol skeleton and an ester group are preferable, and an aromatic compound having a bisphenol skeleton and an oxyalkylene group is more preferable. One or more kinds of the aromatic compound (C) may be used.

[0032] 〔Aromatic compound (C1) having an oxyalkylene group〕 The aromatic compound (C1) having an oxyalkylene group has an aromatic ring and an oxyalkylene group, and is not particularly limited as long as it does not have an ester group. For example, an aromatic compound (C1-1) having an alkylaryl group and an oxyalkylene group, an aromatic compound (C1-2) having an arylalkyl group and an oxyalkylene group, an aromatic compound (C1-3) having a diarylmethane skeleton and an oxyalkylene group, etc. can be mentioned, and it is preferably an alkylene oxide adduct of an alkylphenol (having 6 to 40 carbon atoms), an alkylene oxide adduct of an aromatic alcohol (having 6 to 40 carbon atoms), and an alkylene oxide adduct of a compound having a bisphenol skeleton, and more preferably an alkylene oxide adduct of an alkylphenol (having 8 to 30 carbon atoms), an alkylene oxide adduct of an aromatic alcohol (having 8 to 30 carbon atoms), and an alkylene oxide adduct of a compound having a bisphenol skeleton.

[0033] Examples of the aromatic compound (C1-1) having an alkylaryl group and an oxyalkylene group include alkylene oxide adducts of alkylphenols. Examples of the aromatic compound (C1-2) having an arylalkyl group and an oxyalkylene group include alkylene oxide adducts of aromatic alcohols having an arylalkyl group. Examples of the aromatic compound (C1-3) having a diarylmethane skeleton and an oxyalkylene group include an alkylene oxide adduct of a compound having a bisphenol skeleton. One or more aromatic compounds (C1) having an oxyalkylene group may be used.

[0034] Examples of the alkylphenol constituting the aromatic compound (C1-1) having an alkylaryl group and an oxyalkylene group include styrenated phenol, distyrenated phenol, tristyrenated phenol, benzylphenol, dibenzylphenol, tribenzylphenol, butylphenol, isobutylphenol, pentylphenol, hexylphenol, heptylphenol, octylphenol, nonylphenol, decylphenol, dodecylphenol, tridecylphenol, and the like. Among these, at least one selected from styrenated phenol, distyrenated phenol, tristyrenated phenol, benzylphenol, dibenzylphenol, tribenzylphenol, octylphenol, nonylphenol, decylphenol, dodecylphenol, and tridecylphenol is preferable in terms of improving the aggregability during flame resistance.

[0035] The alkylene oxide adduct of alkylphenol is not particularly limited, but styrenated phenol alkylene oxide adduct, distyrenated phenol alkylene oxide adduct, tristyrenated phenol alkylene oxide adduct, benzylphenol alkylene oxide adduct, dibenzylphenol alkylene oxide adduct, tribenzylphenol alkylene oxide adduct, octylphenol alkylene oxide adduct, nonylphenol alkylene oxide adduct, decylphenol alkylene oxide adduct, dodecylphenol alkylene oxide adduct, tridecylphenol alkylene oxide adduct are preferred. Styrenated phenol alkylene oxide adduct, distyrenated phenol alkylene oxide adduct, tristyrenated phenol alkylene oxide adduct, benzylphenol alkylene oxide adduct, dibenzylphenol alkylene oxide adduct, tribenzylphenol alkylene oxide adduct are more preferred. Distyrenated phenol alkylene oxide adduct, tristyrenated phenol alkylene oxide adduct, dibenzylphenol alkylene oxide adduct, tribenzylphenol alkylene oxide adduct are even more preferred.

[0036] The number of moles of alkylene oxide added in the alkylene oxide adduct of alkylphenol is preferably 2 to 60 moles. The upper limit of the number of moles of addition 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 of addition is more preferably 4 moles, even more preferably 6 moles, and particularly preferably 8 moles. Also, for example, 6 to 30 moles is more preferred, and 6 to 20 moles is particularly preferred. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, and more preferably contains ethylene oxide. The alkylene oxide may be randomly added or block-added.

[0037] Examples of the aromatic alcohol having an arylalkyl group that constitutes the aromatic compound (C1-2) having an arylalkyl group and an oxyalkylene group include benzyl alcohol, phenylethanol, phenylpropanol, phenylbutanol, phenylpentanol, α-methylbenzyl alcohol, β-phenylethyl alcohol, γ-phenylpropyl alcohol, and the like. Among these, at least one selected from benzyl alcohol, phenylethanol, phenylpropanol, α-methylbenzyl alcohol, β-phenylethyl alcohol, and γ-phenylpropyl alcohol is preferable in terms of improving the aggregability during flame retardant treatment.

[0038] The alkylene oxide adduct of the aromatic alcohol having an arylalkyl group is not particularly limited, but in terms of improving the aggregability during flame retardant treatment, the alkylene oxide adduct of benzyl alcohol, the alkylene oxide adduct of phenylethanol, the alkylene oxide adduct of phenylpropanol, the alkylene oxide adduct of α-methylbenzyl alcohol, the alkylene oxide adduct of β-phenylethyl alcohol, and the alkylene oxide adduct of γ-phenylpropyl alcohol are preferable. The alkylene oxide adduct of benzyl alcohol, the alkylene oxide adduct of phenylethanol, the alkylene oxide adduct of α-methylbenzyl alcohol, and the alkylene oxide adduct of β-phenylethyl alcohol are more preferable, and the alkylene oxide adduct of benzyl alcohol and the alkylene oxide adduct of α-methylbenzyl alcohol are even more preferable.

[0039] The number of moles of alkylene oxide added in the alkylene oxide adduct of the aromatic alcohol having an arylalkyl group is preferably 2 to 60 moles. The upper limit of the number of moles of addition is more preferably 30 moles, even more preferably 20 moles, and particularly preferably 15 moles. On the other hand, the lower limit of the number of moles of addition is more preferably 4 moles, even more preferably 6 moles, and particularly preferably 8 moles. Also, for example, 4 to 20 moles is more preferable, and 4 to 15 moles is particularly preferable. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, and more preferably contains ethylene oxide. The alkylene oxide may be added randomly or in blocks.

[0040] In the compound having a bisphenol skeleton that constitutes the alkylene oxide adduct of the compound having a bisphenol skeleton, examples of the bisphenol skeleton include bisphenol A, AP, AF, B, BP, C, E, F, G, PH, TMC, Z, etc. Among these, at least one selected from the bisphenol A skeleton, bisphenol B skeleton, bisphenol E skeleton, and bisphenol F skeleton is preferable in terms of improving the focusing property during flame resistance. The alkylene oxide adduct of the compound having a bisphenol skeleton is not particularly limited, but in terms of improving the focusing property during flame resistance, bisphenol A alkylene oxide adduct, bisphenol B alkylene oxide adduct, bisphenol E alkylene oxide adduct, and bisphenol F alkylene oxide adduct are preferable, bisphenol A ethylene oxide adduct, bisphenol E alkylene oxide adduct, and bisphenol F alkylene oxide adduct are more preferable, and bisphenol A ethylene oxide adduct is even more preferable.

[0041] The number of moles of the added alkylene oxide in the alkylene oxide adduct of the compound having a bisphenol skeleton is preferably 2 to 60 moles. The upper limit of the number of moles of the addition is more preferably 30 moles, even more preferably 18 moles, and particularly preferably 10 moles. On the other hand, the lower limit of the number of moles of the addition is more preferably 4 moles, even more preferably 6 moles, and particularly preferably 8 moles. Also, for example, 4 to 18 moles is more preferable, and 6 to 18 moles is particularly preferable. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, and more preferably contains ethylene oxide. The alkylene oxide may be added randomly or in blocks.

[0042] [Aromatic compound (C2) having an ester group] The aromatic compound (C2) having an ester group is not particularly limited as long as it has an aromatic ring and an ester group. For example, esters (C2-1) of aromatic alcohols and / or phenol compounds with aliphatic carboxylic acids, esters (C2-2) of aromatic carboxylic acids with aliphatic alcohols, esters (C2-3) of aromatic alcohols and / or phenol compounds with aromatic carboxylic acids, etc. can be mentioned. The aromatic compound (C2) having an ester group may be used alone or in combination of two or more.

[0043] The aromatic alcohols and phenol compounds constituting the aromatic compound (C2) having an ester group are not particularly limited. Examples of aromatic alcohols include aromatic alcohols having an arylalkyl group and alkylene oxide adducts thereof. Examples of phenol compounds include compounds having the aforementioned bisphenol skeleton, alkylphenols, and alkylene oxide adducts thereof. From the viewpoint of improving the aggregation property during flame retardant treatment, compounds having a bisphenol skeleton, alkylphenols, and alkylene oxide adducts thereof are preferred, and bisphenol A, bisphenol B, bisphenol E, bisphenol F, (poly)styrenated phenol, (poly)benzylphenol, and ethylene oxide adducts thereof are more preferred. As the alkylene oxide added to the aromatic alcohol and phenol compound, at least one selected from ethylene oxide and propylene oxide is preferred, more preferably including ethylene oxide, and even more preferably ethylene oxide.

[0044] The aromatic carboxylic acids constituting the aromatic compound (C2) having an ester group are not particularly limited. Examples 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, naphthalene dicarboxylic acid, phenylmalonic acid, phenylsuccinic acid, β-phenylglutaric acid, α-phenyladipic acid, β-phenyladipic acid, biphenyl-2,2'- or 4,4'-dicarboxylic acid, sodium 5-sulfoisophthalate and potassium 5-sulfoisophthalate, and derivatives of these dicarboxylic acids, and trimellitic acid, pyromellitic acid, and derivatives of these polyvalent carboxylic acids having a valence of 3 or more. Examples of aromatic monocarboxylic acids having 7 to 14 carbon atoms include benzoic acid, salicylic acid, acetylsalicylic acid, and the like. Among these, diphenyl ether dicarboxylic acid, naphthalene dicarboxylic acid, biphenyl-2,2'- or 4,4'-dicarboxylic acid, trimellitic acid, and pyromellitic acid are preferred in terms of improving the aggregability during flame retardant treatment, with diphenyl ether dicarboxylic acid, trimellitic acid, and pyromellitic acid being more preferred, and trimellitic acid and pyromellitic acid being even more preferred.

[0045] The aliphatic carboxylic acids constituting the aromatic compound (C2) having an ester group are not particularly limited, and examples 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.

[0046] Examples of aliphatic monocarboxylic acids 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, octacosanoic acid, ricinoleic acid, oleic acid, isostearic acid, isoarachidic acid, etc. From the viewpoint of compatibility with the silicone compound (S), decanoic acid, dodecanoic acid, and tridecanoic acid are preferred.

[0047] Examples of aliphatic polycarboxylic acids 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, citraconic acid, etc. From the viewpoint of improving the aggregability during flame retardancy, succinic acid and adipic acid are preferred.

[0048] The aliphatic alcohol constituting the aromatic compound (C2) having an ester group is not particularly limited, and examples include aliphatic alcohols having 2 to 24 carbon atoms and alkylene oxide adducts of aliphatic alcohols having 2 to 24 carbon atoms. The aliphatic alcohol may be saturated or unsaturated, and may be linear or branched. Examples of the aliphatic alcohol constituting the aromatic compound (C2) having an ester group include butyl alcohol, octyl alcohol, nonanol, lauryl alcohol, stearyl alcohol, ceryl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, isotetracosanyl alcohol, 2-propyl alcohol, 12-eicosyl alcohol, vinyl alcohol, butenyl alcohol, hexadecenyl alcohol, oleyl alcohol, eicosenyl alcohol, linear secondary alcohols having 10 to 16 carbon atoms, ethylene glycol, propylene glycol, and alkylene oxide adducts thereof. In terms of compatibility with the silicone compound (S), octyl alcohol, nonanol, lauryl alcohol, and stearyl alcohol are preferred, and nonanol and lauryl alcohol are more preferred.

[0049] Examples of the ester (C2-1) of an aromatic alcohol and / or a phenol compound and an aliphatic carboxylic acid include esters of the above aromatic alcohols and aliphatic carboxylic acids. Among these, esters of bisphenol A and an aliphatic carboxylic acid, and esters of a compound obtained by adding 1 to 20 moles of an alkylene oxide to bisphenol A and an aliphatic carboxylic acid are preferred in terms of improving the aggregation property during flame retardant treatment.

[0050] Examples of the ester (C2-2) of an aromatic carboxylic acid and an aliphatic alcohol include esters of the above aromatic carboxylic acids and aliphatic alcohols. Among these, esters of trimellitic acid and an aliphatic alcohol, and esters of pyromellitic acid and an aliphatic alcohol are preferred in terms of improving the aggregation property during flame retardant treatment.

[0051] Examples of the ester (C2-3) of an aromatic alcohol and / or a phenol compound and an aromatic carboxylic acid include esters of the above aromatic alcohols and / or phenol compounds and aromatic carboxylic acids. Among these, benzyl benzoate and benzyl salicylate are preferred in terms of improving the aggregation property during flame retardant treatment.

[0052] [Aliphatic compound (D) having an oxyalkylene group] The treatment agent of the present invention may contain an aliphatic compound (D) having an oxyalkylene group. The aliphatic compound (D) having an oxyalkylene group is not particularly limited as long as it is an aliphatic compound having an oxyalkylene group. Examples include aliphatic alcohol alkylene oxide adducts (D1), aliphatic alkylene oxide adducts having an ester group (D2), etc. Among them, aliphatic alcohol alkylene oxide adducts (D1) are preferred in terms of anti-fusing property and permeability into the fiber bundle. One or more kinds of aliphatic compounds (D) having an oxyalkylene group may be used.

[0053] Examples of the aliphatic alcohol alkylene oxide adduct (D1) include alkylene oxide adducts of aliphatic alcohols, which do not have an ester group. As the alkylene oxide adduct of aliphatic alcohol, alkylene oxide adducts of 1-6 valent aliphatic alcohols are preferred in terms of permeability into the fiber bundle, and alkylene oxide adducts of 1-3 valent aliphatic alcohols are more preferred. The aliphatic alcohol constituting the aliphatic alcohol alkylene oxide adduct (D1) is not particularly limited, and examples include aliphatic alcohols having 2-24 carbon atoms. The aliphatic alcohol may be saturated or unsaturated, linear or branched, monovalent or polyvalent. In terms of anti-fusing property, linear saturated aliphatic alcohols of 1-3 valency and branched saturated aliphatic alcohols of 1-3 valency are preferred. One or more kinds of aliphatic alcohol alkylene oxide adducts (D1) 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. For example, 8-20 is preferred, and 8-18 is more preferred.

[0054] Examples of the aliphatic alcohol constituting the aliphatic alcohol alkylene oxide adduct (D1) include butyl alcohol, octyl alcohol, nonanol, lauryl alcohol, stearyl alcohol, ceryl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, isotetracosanyl alcohol, 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, butylene glycol, etc. In terms of anti-blocking properties, octyl alcohol, nonanol, lauryl alcohol, stearyl alcohol, ceryl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol, eicosyl alcohol are preferred, and octyl alcohol, nonanol, lauryl alcohol, stearyl alcohol, ceryl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, isododecyl alcohol, isohexadecyl alcohol, isostearyl alcohol are more preferred.

[0055] The number of moles of alkylene oxide added in the aliphatic alcohol alkylene oxide adduct (D1) is preferably 1 to 50 moles. The upper limit of the number of moles of addition is more preferably 40 moles, further preferably 30 moles, and particularly preferably 20 moles. On the other hand, the lower limit of the number of moles of addition is more preferably 4 moles, further preferably 5 moles, and particularly preferably 6 moles. Also, for example, 4 to 30 moles is more preferable, and 6 to 30 moles is particularly preferable. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, and more preferably contains ethylene oxide. The alkylene oxide may be randomly added or block-added.

[0056] Examples of the aliphatic alcohol alkylene oxide adduct (D1) 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-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, oxyethylene-oxypropylene block or random copolymer, and the like.

[0057] Examples of the aliphatic alcohol alkylene oxide adduct (D2) having an ester group include those having a structure in which an alkylene oxide is added to an aliphatic carboxylic acid (D2-1), those having a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol (D2-2), and the like. One or more kinds of the aliphatic alcohol alkylene oxide adduct (D2) having an ester group may be used.

[0058] The aliphatic carboxylic acid constituting the aliphatic alcohol alkylene oxide adduct (D2) having an ester group is not particularly limited, and 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.

[0059] Examples of aliphatic monocarboxylic acids 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, octacosanoic acid, ricinoleic acid, oleic acid, isostearic acid, isoarachidic acid, etc. From the viewpoint of anti-fusing property, 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) are preferred.

[0060] As for the number of moles of alkylene oxide added in the aliphatic alkylene oxide adduct (D2) having an ester group, 1 to 40 moles are preferred. The upper limit of the number of moles of addition is more preferably 30 moles, still more preferably 25 moles, and particularly preferably 20 moles. On the other hand, the lower limit of the number of moles of addition is more preferably 4 moles, still more preferably 5 moles, and particularly preferably 6 moles. Also, for example, 4 to 20 moles are more preferred, and 6 to 20 moles are particularly preferred. The alkylene oxide preferably contains at least one selected from ethylene oxide and propylene oxide, and more preferably contains ethylene oxide. The alkylene oxide may be randomly added or block-added.

[0061] Examples of those having a structure in which an alkylene oxide is added to an aliphatic carboxylic acid (D2-1) include the compounds in which an alkylene oxide is added to the aliphatic carboxylic acid mentioned above. From the viewpoint of permeability into the fiber bundle, those having a structure in which 1 to 20 moles of an alkylene oxide is added to a carboxylic acid having 8 to 18 carbon atoms are preferred.

[0062] As the polyhydric alcohol constituting a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol (D2-2), a C2-C6 di- to tetravalent alcohol is preferred, and among these, a C2-C6 di- to trivalent alcohol is more preferred. Specifically, for example, divalent alcohols such as propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol; trivalent alcohols such as glycerin, trimethylolpropane; and tetravalent or higher alcohols such as pentaerythritol, sorbitan, sorbitol can be mentioned.

[0063] Examples of those having a structure in which an alkylene oxide is added to an ester compound of an aliphatic carboxylic acid and a polyhydric alcohol (D2-2) include the compounds in which an alkylene oxide is added to the ester compound of an aliphatic carboxylic acid and a polyhydric alcohol mentioned above. From the viewpoint of anti-fusing property, an alkylene oxide adduct of glycerin fatty acid ester and an alkylene oxide adduct of sorbitan fatty acid ester are preferred.

[0064] [Bronsted acid compound (E)] It is preferable that the treatment agent of the present invention contains a Bronsted acid compound (E) from the viewpoint of the stability of the treatment agent in an aqueous system. The Bronsted acid compound (E) 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.

[0065] An organic carboxylic acid compound refers to an organic compound having a carboxyl group in its molecular structure. Examples of organic carboxylic acid compounds include, but are not limited to, aliphatic monocarboxylic acids, alkyl ether carboxylic acids, aliphatic polycarboxylic acids, aromatic carboxylic acids, aromatic polycarboxylic acids, amino acids, and the like.

[0066] 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, iso-eicosanoic acid, gadoleic acid, eicosenoic acid, docosanoic acid, isodocosanoic acid, erucic acid, tetracosanoic acid, isotetracosanoic acid, nervonic acid, serotic acid, montanic acid, melissic acid, and the like.

[0067] 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 moles. Examples of the alkyl group include an octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, and octadecyl group. Examples of the polyoxyalkylene group include a polyoxyethylene group, polyoxypropylene group, and polyoxypolypropylene group.

[0068] Examples of aliphatic polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, and derivatives thereof.

[0069] Examples of aromatic monocarboxylic acids include benzoic acid, cinnamic acid, naphthoic acid, toluic acid, and derivatives thereof.

[0070] Examples of aromatic polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and derivatives thereof.

[0071] An amino acid is a compound having both an amino group and a carboxyl group in its molecular structure. Examples include alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline, glycine, tyrosine, serine, threonine, cysteine, asparagine, glutamine, lysine, arginine, histidine, aspartic acid, glutamic acid, and the like.

[0072] An inorganic acid refers to an acid composed of non-metal atoms as components. Examples of inorganic acids include sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, and the like.

[0073] Examples of organic sulfonic acid compounds include alkylbenzene sulfonic acid, polyoxyalkylene alkyl ether sulfonic acid, higher fatty acid amide sulfonic acid, alkyl sulfate monoester, polyoxyalkylene sulfate monoester, and the like.

[0074] Examples of organic phosphate ester compounds include alkyl phosphate monoester, alkyl phosphate diester, polyoxyalkylene alkyl ether phosphate monoester, polyoxyalkylene alkyl ether phosphate diester, polyoxyalkylene alkyl phenyl ether phosphate monoester, polyoxyalkylene alkyl phenyl ether phosphate diester, and the like.

[0075] Examples of organic sulfate ester compounds include alkyl sulfate ester, polyoxyalkylene alkyl sulfate ester, alkyl phenyl sulfate ester, polyoxyalkylene alkyl phenyl sulfate ester, and the like.

[0076] Examples of organic phosphonic acid compounds include alkyl phosphonic acid, aromatic phosphonic acid, polyoxyalkylene alkyl ether phosphonic acid, and the like.

[0077] The pKa of the Bronsted compound (E) is preferably from 0 to 7, more preferably from 1 to 6.5, and even more preferably from 2 to 6, from the viewpoint of the stability of the treating agent in an aqueous system.

[0078] The Bronsted acid compound (E) preferably contains at least one selected from organic carboxylic acid compounds, inorganic acids, and organic phosphate ester compounds, more preferably contains at least one selected from lactic acid, alkyl ether carboxylic acids, organic phosphate ester compounds, phosphoric acid, and acetic acid, and even more preferably contains at least one selected from alkyl ether carboxylic acids, organic phosphate ester compounds, acetic acid, and phosphoric acid. The Bronsted acid compound (E) may be used alone or in combination of two or more.

[0079] [Treating Agent for Carbon Fiber Precursor] The treating agent for a carbon fiber precursor of the present invention contains a silicone compound (S) and an aromatic compound (C), the silicone compound (S) contains a silicone having an amino group (SA) and a silicone having a polyether group (SB), the aromatic compound (C) contains at least one selected from an aromatic compound having an oxyalkylene group (C1) and an aromatic compound having an ester group (C2), and the proportion of the silicone compound (S) in the non-volatile matter is 65% by weight or less. The non-volatile matter concentration in the present invention is obtained by precisely weighing the remaining weight on an aluminum sheet when the fluctuation range of the volatile matter becomes 0.15% in 150 seconds after spreading 2.0 to 3.0 g of the treating agent flat on an aluminum sheet (φ110 mm) and drying it at 110 °C under infrared lamp irradiation, and calculating the ratio (percentage) of the remaining weight after heating to the weight before heating. The non-volatile matter in the present invention refers to the remaining matter on the aluminum sheet when the fluctuation range of the volatile matter becomes 0.15% in 150 seconds after drying in the same manner as the non-volatile matter concentration measurement procedure.

[0080] When the carbon fiber precursor treated with the treating agent of the present invention is stored for a long period of time, the reason why the deterioration of the carbon fiber precursor can be suppressed is that it contains a specific silicone compound (S) and a specific aromatic compound (C), and the ratio of the silicone compound (S) in the non-volatile content is 65% by weight or less, so that the components of the treating agent applied to the precursor do not separate on the precursor and are kept in a uniform state, and a part of the treating agent components can be suppressed from penetrating into the carbon fiber precursor. Therefore, it is considered that the increase in the hardness of the carbon fiber precursor fiber bundle over time is prevented.

[0081] The acid value of the treating agent of the present invention is preferably 0.1 to 30 mgKOH / g from the viewpoint of the stability of the treating agent in an aqueous system. The upper limit of the acid value is more preferably 25 mgKOH / g, further preferably 20 mgKOH / g, particularly preferably 15 mgKOH / g, and most preferably 10 mgKOH / g. On the other hand, the lower limit of the acid value is more preferably 0.3 mgKOH / g, further preferably 0.5 mgKOH / g, particularly preferably 0.6 mgKOH / g, and most preferably 0.8 mgKOH / g. Also, for example, 0.5 to 20 mgKOH / g is more preferable, and 0.5 to 15 mgKOH / g is further preferable. The acid value of the treating agent in the present invention is determined by the method described in the examples.

[0082] The ratio of the silicone compound (S) in the non-volatile content of the treating agent of the present invention is not particularly limited as long as it is 65% by weight or less, but from the viewpoint of suppressing the separation of the components of the treating agent, it is preferably 1 to 65% by weight. The upper limit of the ratio is more preferably 60% by weight, further preferably 55% by weight, particularly preferably 50% by weight, and most preferably 40% by weight. On the other hand, the lower limit of the ratio is more preferably 5% by weight, further preferably 10% by weight, and particularly preferably 15% by weight. Also, for example, 10 to 60% by weight is more preferable, 10 to 55% by weight is further preferable, and 15 to 50% by weight is particularly preferable. When the ratio exceeds 65% by weight, the components of the treating agent are likely to separate over time, and a part of the treating agent components is considered to penetrate into the carbon fiber precursor, tending to cause deterioration of the carbon fiber precursor over time.

[0083] The proportion of silicone with an amino group (SA) in the non-volatile matter of the treatment agent of the present invention is preferably 1 to 60% by weight from the viewpoint of the aggregation property during flame resistance. The upper limit of the proportion is more preferably 55% by weight, further preferably 50% by weight, and particularly preferably 45% by weight. On the other hand, the lower limit of the proportion is more preferably 5% by weight, further preferably 10% by weight, and particularly preferably 15% by weight. Also, for example, 10 to 50% by weight is more preferable, 15 to 50% by weight is further preferable, and 20 to 50% by weight is particularly preferable.

[0084] The proportion of silicone with a polyether group (SB) in the non-volatile matter of the treatment agent of the present invention is preferably 0.1 to 30% by weight from the viewpoint of suppressing the component separation of the treatment agent. The upper limit of the proportion is more preferably 25% by weight, further preferably 20% by weight, and particularly preferably 15% by weight. On the other hand, the lower limit of the proportion is more preferably 0.5% by weight, further preferably 0.7% by weight, and particularly preferably 1.0% by weight. Also, for example, 0.5 to 20% by weight is more preferable, 0.7 to 20% by weight is further preferable, and 0.7 to 15% by weight is particularly preferable.

[0085] The weight ratio (SB / SA) of silicone with a polyether group (SB) to silicone with an amino group (SA) is preferably 0.01 to 5.0 from the viewpoint of suppressing the component separation of the treatment agent. The upper limit of the ratio is more preferably 2.0, further preferably 1.0, and particularly preferably 0.5. On the other hand, the lower limit of the weight ratio is more preferably 0.04, further preferably 0.07, and particularly preferably 0.1. Also, for example, 0.04 to 2.0 is more preferable, 0.04 to 1.0 is further preferable, and 0.07 to 1.0 is particularly preferable.

[0086] The proportion of the aromatic compound (C) in the non-volatile content of the treating agent of the present invention is preferably 35 to 95% by weight from the viewpoint of the aggregability during flame retardant treatment. The upper limit of the proportion is more preferably 90% by weight, further preferably 80% by weight, and particularly preferably 75% by weight. On the other hand, the lower limit of the proportion is more preferably 40% by weight, further preferably 45% by weight, and particularly preferably 50% by weight. Also, for example, 40 to 80% by weight is more preferable, 45 to 80% by weight is further preferable, and 50 to 80% by weight is particularly preferable.

[0087] The proportion of the aromatic compound (C1) having an oxyalkylene group in the non-volatile content of the treating agent of the present invention is preferably 10 to 95% by weight from the viewpoint of the aggregability during flame retardant treatment. The upper limit of the proportion is more preferably 90% by weight, further preferably 80% by weight, and particularly preferably 75% by weight. On the other hand, the lower limit of the proportion is more preferably 15% by weight, further preferably 20% by weight, and particularly preferably 25% by weight. Also, for example, 10 to 80% by weight is more preferable, 15 to 80% by weight is further preferable, and 20 to 80% by weight is particularly preferable.

[0088] The proportion of the aromatic compound (C2) having an ester group in the non-volatile content of the treating agent of the present invention is preferably 5 to 80% by weight from the viewpoint of the aggregability during flame retardant treatment. The upper limit of the proportion is more preferably 75% by weight, further preferably 70% by weight, and particularly preferably 65% by weight. On the other hand, the lower limit of the proportion is more preferably 10% by weight, further preferably 15% by weight, and particularly preferably 20% by weight. Also, for example, 10 to 70% by weight is more preferable, 10 to 65% by weight is further preferable, and 15 to 65% by weight is particularly preferable.

[0089] The weight ratio of the silicone compound (S) to the total of the aromatic compound (C1) having an oxyalkylene group and the aromatic compound (C2) having an ester group ((S) / (C1 + C2)) is preferably 0.05 to 1.85 in terms of the aggregability during flame retardant treatment. The upper limit of the ratio is more preferably 1.5, still more preferably 1.2, and particularly preferably 1. On the other hand, the lower limit of the weight ratio is more preferably 0.1, still more preferably 0.25, and particularly preferably 0.33. Further, for example, 0.25 to 1.5 is more preferable, 0.25 to 1.2 is still more preferable, and 0.25 to 1 is particularly preferable.

[0090] When the treating agent of the present invention further contains an aliphatic compound (D) having an oxyalkylene group, the proportion of the aliphatic compound (D) having an oxyalkylene group in the non-volatile content of the treating agent of the present invention is preferably 0.2 to 30% by weight in terms of preventing fusion. The upper limit of the proportion is more preferably 25% by weight, still more preferably 20% by weight, and particularly preferably 15% by weight. On the other hand, the lower limit of the proportion is more preferably 0.5% by weight, still more preferably 1% by weight, and particularly preferably 2% by weight. Further, for example, 0.5 to 20% by weight is more preferable, 0.5 to 15% by weight is still more preferable, and 1 to 15% by weight is particularly preferable.

[0091] When the treating agent of the present invention further contains a Bronsted acid compound (E), the proportion of the Bronsted acid compound (E) in the non-volatile content of the treating agent of the present invention is preferably 0.05 to 10% by weight in terms of the stability of the treating agent in an aqueous system. The upper limit of the weight ratio is more preferably 8.5% by weight, still more preferably 7% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of the weight ratio is more preferably 0.65% by weight, still more preferably 0.80% by weight, and particularly preferably 1% by weight. Further, for example, 0.80 to 7% by weight is more preferable, and 1 to 5% by weight is still more preferable.

[0092] When the treatment agent of the present invention further contains a Bronsted acid compound (E), the weight ratio ((E) / (A)) of the Bronsted acid compound (E) to the silicone having an amino group (SA) is preferably 0.005 to 0.5 from the viewpoint of the stability of the treatment agent in an aqueous system. The upper limit of the ratio is more preferably 0.3, further preferably 0.25, particularly preferably 0.2, and most preferably 0.15. On the other hand, the lower limit of the ratio is more preferably 0.0065, further preferably 0.08, particularly preferably 0.01, and most preferably 0.015. Also, for example, 0.01 to 0.3 is more preferable and 0.01 to 0.2 is further preferable.

[0093] 〔Other nonionic surfactants〕 From the viewpoint of enhancing the emulsifying property, the treatment agent of the present invention preferably further contains other nonionic surfactants. Here, other nonionic surfactants refer to nonionic surfactants other than the aromatic compound (C) and the aliphatic compound (D) having an oxyalkylene group. Examples of 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 other nonionic surfactants is preferably 2000 or less, more preferably 200 to 1800, still more preferably 300 to 1500, and further preferably 500 to 1000. One or more other nonionic surfactants may be used.

[0094] When the treatment agent of the present invention contains other nonionic surfactants, in terms of emulsion stability, the weight ratio of the other nonionic surfactant in the nonvolatile content of the treatment agent is preferably 0.1 to 10% by weight. The upper limit of this ratio is more preferably 8.5% by weight, still more preferably 7.0% by weight, and particularly preferably 5.0% by weight. On the other hand, the lower limit of this ratio is more preferably 0.25% by weight, still more preferably 0.4% by weight, and particularly preferably 0.5% by weight. Further, for example, 0.25 to 8.5% by weight is more preferable, 0.4 to 7.0% by weight is still more preferable, and 0.5 to 5.0% by weight is particularly preferable.

[0095] 〔Other surfactants〕 The treatment agent of the present invention may contain surfactants other than the aromatic compound (C), the aliphatic compound (D) having an oxyalkylene group, the Bronsted acid compound (E), and other nonionic surfactants, as long as the effects of the present invention are not inhibited. The other surfactants are used as emulsifiers, antistatic agents, etc. The other surfactants are not particularly limited, and known ones can be appropriately selected and used from anionic surfactants, cationic surfactants, and amphoteric surfactants. The surfactant may be one kind or two or more kinds may be used in combination.

[0096] Examples of cationic surfactants include alkyl quaternary ammonium salts such as lauryltrimethylammonium chloride, myristyltrimethylammonium chloride, palmityltrimethylammonium chloride, stearyltrimethylammonium chloride, oleyltrimethylammonium chloride, cetyltrimethylammonium chloride, behenyltrimethylammonium chloride, coconut oil alkyltrimethylammonium chloride, tallow alkyltrimethylammonium chloride, stearyltrimethylammonium bromide, coconut oil alkyltrimethylammonium bromide, cetyltrimethylammonium methosulfate, oleyl dimethylethylammonium ethosulfate, dioctyldimethylammonium chloride, dilauryl dimethylammonium chloride, distearyl dimethylammonium chloride, octadecyl diethylmethylammonium sulfate; acylamidealkyl quaternary ammonium salts such as N-(2-hydroxyethyl)-N,N-dimethyl-N-stearoyl amidopropylammonium nitrate, lanolin fatty acid amidopropylethyldimethylammonium ethosulfate, lauroylamideethylmethyldiethylammonium methosulfate; alkyl isoquinolinium salts such as lauryl isoquinolinium chloride; benzalkonium salts such as lauryl dimethylbenzylammonium chloride, stearyl dimethylbenzylammonium chloride; pyridinium salts such as cetylpyridinium chloride; imidazolinium salts such as oleyl hydroxyethylimidazolinium ethosulfate, lauryl hydroxyethylimidazolinium ethosulfate; acyl basic amino acid alkyl ester salts such as N-cocoyl arginine ethyl ester pyrrolidone carboxylate, N-lauroyl lysine ethyl ethyl ester chloride; primary amine salts such as laurylamine chloride, stearylamine bromide, hydrogenated tallow alkylamine chloride, rosinamine acetate;Secondary amine salts such as cetylmethylamine sulfate, laurylmethylamine chloride, dilaurylamine acetate, stearylethylamine bromide, laurylpropylamine acetate, dioctylamine chloride, octadecylet hylamine hydroxide, etc.; Tertiary amine salts such as dilaurylmethylamine sulfate, laurylethylamine chloride, laurylethylmethylamine bromide, diethanolstearylamide et hylamine trihydroxyethyl phosphate salt, stearylamide ethylethanolamine urea polycondensate acetate, etc.; Fatty acid amide guanidinium salts; Alkyltrialkylene glycol ammonium salts such as lauryltriethylene glycol ammonium hydroxide, etc. can be mentioned.;

[0097] Examples of amphoteric surfactants include imidazoline - type amphoteric surfactants such as 2 - undecyl - N,N - (hydroxyethylcarboxymethyl) - 2 - imidazoline sodium, 2 - cocoyl - 2 - imidazolinium hydroxide - 1 - carboxyethyloxy 2 - sodium salt, etc.; Betaine - type amphoteric surfactants such as 2 - heptadecyl - N - carboxymethyl - N - hydroxyethylimidazolinium betaine, lauryldimethylaminoacetic acid betaine, alkyl betaine, amide betaine, sulfobetaine, etc.; Amino acid - type amphoteric surfactants such as N - laurylglycine, N - laurylβ - alanine, N - stearylβ - alanine, etc.

[0098] 〔Other Components〕 The treatment agent for carbon fiber precursors of the present invention may contain other components other than the above - mentioned components as long as the effects of the present invention are not inhibited. Other components include antioxidants such as phenolic, amine - based, sulfur - based, phosphorus - based, quinone - based, etc.; Antistatic agents such as quaternary ammonium salt - type cationic surfactants, amine salt - type cationic surfactants, etc.; Lubricants such as alkyl esters of higher alcohols, higher alcohol ethers, waxes, etc.; Antibacterial agents; Preservatives; Rust preventives; And hygroscopic agents, etc.

[0099] In addition, the treatment agent of the present invention may contain one or more low molecular weight silicones. Examples of low molecular weight silicones include linear or cyclic silicones having, for example, 2 to 7 silicon atoms. Specific examples of low molecular weight silicones include octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, heptamethyloctyltrisiloxane, hexamethyldisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, and the like. These low molecular weight silicones may be substituted with groups represented by the general formula (2) or the like. These low molecular weight silicones may be contained as trace components of the silicone (S). The content of the low molecular weight silicone in the treatment agent of the present invention is preferably 5 parts by weight or less with respect to 100 parts by weight of the silicone (S).

[0100] The treatment agent for carbon fiber precursors of the present invention preferably contains at least one selected from a silicone compound (S) containing a silicone (SA) having an amino group and a silicone (SB) having a polyether group, an aromatic compound (C1) having an oxyalkylene group, and an aromatic compound (C2) having an ester group, and an aromatic compound (C), and, if necessary, an aliphatic compound (D) having an oxyalkylene group, a Bronsted acid compound (E), and other components are in a state of being dissolved, solubilized, emulsified, or dispersed in water. There are no particular limitations on the weight ratio of water and the weight ratio of non-volatile matter in the treatment agent for carbon fiber precursors as a whole. For example, it may be appropriately determined in consideration of the transportation cost when transporting the treatment agent for carbon fiber precursors of the present invention and the handleability due to the emulsion viscosity. The weight ratio of water in the treatment agent for carbon fiber precursors as a whole is preferably 0.1 to 99.9% by weight, more preferably 10 to 99.5% by weight, and particularly preferably 50 to 99% by weight. The weight ratio (concentration) of non-volatile matter in the treatment agent for carbon fiber precursors as a whole 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.

[0101] The treatment agent for carbon fiber precursors of the present invention can be produced by mixing the components described above. There are no particular limitations on the method for emulsifying and dispersing the components described above, and known methods can be adopted. Examples of such methods include a method in which each component constituting the treatment agent for carbon fiber precursors is put into warm water under stirring for emulsification and dispersion, and a method in which each component constituting the treatment agent for carbon fiber precursors is mixed, and while applying mechanical shear force using a homogenizer, a homomixer, a ball mill, etc., water is gradually added for phase inversion emulsification. Further, a method in which some components are emulsified and then the remaining components are dissolved and dispersed may also be used.

[0102] The treatment agent for carbon fiber precursors of the present invention can be suitably used as a treatment agent for carbon fiber precursors.

[0103] [Carbon Fiber Precursor, Method for Producing the Same, and Method for Producing Carbon Fiber] The carbon fiber precursor of the present invention is obtained by attaching the above-described treatment agent for carbon fiber precursors to the raw material carbon fiber precursor of the carbon fiber precursor and then spinning. The method for producing the carbon fiber precursor of the present invention includes a spinning step of attaching the above-described treatment agent for carbon fiber precursors to the raw material carbon fiber precursor of the carbon fiber precursor and then spinning. The method for producing carbon fiber of the present invention includes a flameproofing treatment step of converting the carbon fiber precursor to which the above-described treatment agent for carbon fiber precursors is attached into a flameproofing fiber, and a carbonization treatment step of further carbonizing the flameproofing fiber. The above-described flameproofing treatment step is preferably a flameproofing treatment step of converting the carbon fiber precursor into a flameproofing fiber in an oxidizing atmosphere at 200 to 300 °C, and the carbonization treatment step is preferably a step of further carbonizing the flameproofing fiber in an inert atmosphere at 300 to 2000 °C. According to the method for producing carbon fiber of the present invention, since the treatment agent for carbon fiber precursors of the present invention is used, the bundling property is improved, the disturbance of the fiber bundle and the unevenness of stretching are reduced, and high-quality carbon fiber can be produced.

[0104] The fiber spinning process is a process of spinning a carbon fiber precursor by attaching a treating agent for carbon fiber precursor to the raw material carbon fiber precursor of the carbon fiber precursor, and preferably includes an attaching process and a stretching process. The attaching process is a process of attaching a treating agent for carbon fiber precursor after spinning the raw material carbon fiber precursor of the carbon fiber precursor. That is, in the attaching process, the treating agent for carbon fiber precursor is attached to the raw material carbon fiber precursor of the carbon fiber precursor. When stretching the raw material carbon fiber precursor of the carbon fiber precursor immediately after spinning, the high magnification stretching after the attaching process is particularly referred to as the "stretching process". The stretching process may be a wet heat stretching method using high-temperature steam (steam) or a dry heat stretching method using a heat roller. The stretching ratio in the stretching process is preferably 2 to 20 times the total stretching ratio with respect to the raw material carbon fiber precursor immediately after spinning.

[0105] The carbon fiber precursor is not limited as long as it is a precursor used for the production of carbon fibers, but is preferably composed of an acrylic fiber mainly composed of polyacrylonitrile obtained by copolymerizing at least 95 mol% or more of acrylonitrile and 5 mol% or less of a flame retardancy promoting component. As the flame retardancy promoting component, a vinyl group-containing compound having copolymerizability with acrylonitrile can be preferably used. Regarding the single fiber fineness of the carbon fiber precursor, there is no particular limitation, but from the balance between performance and production cost, it is preferably 0.1 to 2.0 dtex. Also, regarding the number of single fibers constituting the fiber bundle of the carbon fiber precursor, there is no particular limitation, but from the balance between performance and production cost, it is preferably 1,000 to 96,000.

[0106] The treating agent for carbon fiber precursor may be attached to the raw material carbon fiber precursor of the carbon fiber precursor at any stage of the fiber spinning process, but it is preferably attached once before the stretching process. It may be attached at any stage before the stretching process, for example, immediately after spinning. Furthermore, it may be attached again at any stage after the stretching process, for example, immediately after the stretching process, at the winding stage, or immediately before the flame retardancy treatment process. Regarding the attaching method, it may be attached using a roller or the like, or may be attached by an immersion method, a spray method, or the like.

[0107] In the adhesion treatment step, the application rate of the treatment agent for the carbon fiber precursor is preferably 0.1 to 5% by weight, more preferably 0.3 to 1.5% by weight, based on the weight of the carbon fiber precursor, from the balance between obtaining the anti-sticking effect and anti-fusion effect between fibers and preventing the quality degradation of carbon fibers by the tar product of the treatment agent in the carbonization treatment step. The application rate of the treatment agent for the carbon fiber precursor referred to here is defined as the percentage of the weight of the non-volatile matter adhered to the carbon fiber precursor with respect to the weight of the carbon fiber precursor.

[0108] The flame-retardant treatment step is a step of converting the carbon fiber precursor to which the treatment agent for the carbon fiber precursor is adhered into flame-retardant fibers, for example, in an oxidizing atmosphere at 200 to 300°C. The oxidizing atmosphere is usually an air atmosphere. The temperature of the oxidizing atmosphere is preferably 230 to 280°C. In the flame-retardant treatment step, heat treatment is performed for 20 to 100 minutes (preferably 30 to 60 minutes) while applying a tension with a draw ratio of 0.90 to 1.10 (preferably 0.95 to 1.05) to the carbon fiber precursor after the adhesion treatment. In this flame-retardant treatment, flame-retardant fibers having a flame-retardant structure are produced through intramolecular cyclization and oxygen addition to the ring.

[0109] The carbonization treatment process is a process of further carbonizing the flame-resistant fiber, for example, in an inert atmosphere at 300 to 2000 °C. In the carbonization treatment process, first, in a firing furnace having a temperature gradient from 300 °C to 800 °C in an inert atmosphere such as nitrogen or argon, a tension with a draw ratio of 0.95 to 1.15 is applied to the flame-resistant fiber, and heat treatment is performed for several minutes to carry out a preliminary carbonization treatment process (first carbonization treatment process). Then, in order to further progress carbonization and progress graphitization, in an inert atmosphere such as nitrogen or argon, while applying a tension with a draw ratio of 0.95 to 1.05 to the first carbonization treatment process, heat treatment is performed for several minutes to carry out a second carbonization treatment process, and the flame-resistant fiber is carbonized. Regarding the control of the heat treatment temperature in the second carbonization treatment process, 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 according to the required characteristics (tensile strength, elastic modulus, etc.) of the desired carbon fiber.

[0110] In the method for producing carbon fiber of the present invention, when carbon fiber with a higher elastic modulus is desired, a graphitization treatment process can be performed subsequent to the carbonization treatment process. The graphitization treatment process is usually performed at a temperature of 2000 to 3000 °C while applying tension to the fiber obtained in the carbonization treatment process in an inert atmosphere such as nitrogen or argon.

[0111] The carbon fiber thus obtained can be subjected to a surface treatment for enhancing the adhesion strength with the matrix resin when made into a composite material, according to the purpose. As the surface treatment method, a gas phase or liquid phase treatment can be adopted, and from the viewpoint of productivity, a liquid phase treatment with an electrolytic solution such as an acid or an alkali is preferable. Further, various sizing agents excellent in compatibility with the matrix resin can be imparted in order to improve the processability and handleability of the carbon fiber.

Example

[0112] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples described herein. Unless otherwise specified, the percentages (%) and parts shown in the following examples indicate "wt%" and "parts by weight". The measurement of each characteristic value was carried out based on the methods shown below.

[0113] <Application rate of treatment agent> After the carbon fiber precursor after the application of the treatment agent was alkali-melted with potassium hydroxide / sodium butyrate, it was dissolved in water and adjusted to pH 1 with hydrochloric acid. Sodium sulfite and ammonium molybdate were added thereto for color development, and colorimetric determination of silicon molybdenum blue (wavelength 815 mμ) was performed to determine the silicon content. Using the silicon content obtained here and the value of the silicon content in the treatment agent obtained in the same method in advance, the application rate (wt%) of the carbon fiber precursor treatment agent was calculated.

[0114] <Acid value of treatment agent> Measurement was carried out in accordance with the neutralization titration method specified in JIS K0070, and the average value of 5 measurement times was taken as the acid value of the treatment agent.

[0115] <Anti-fusion property> Twenty locations were randomly selected from the carbon fibers, and short fibers with a length of 10 mm were cut out therefrom. The fusion state was observed and judged according to the following evaluation criteria. ◎ and ○ were regarded as passing. ◎: No fusion 〇: Almost no fusion △: Little fusion ×: Many fusions

[0116] <Strand hardness of carbon fiber precursor> The hardness of a carbon fiber precursor strand (length: approximately 50 cm) was measured using a texture analyzer (HANDLE-O-METER HOM-2 manufactured by Daiei Kagaku Seiki Co., Ltd., slit width 5 mm). The measurement was performed 10 times, and it was determined that the smaller the average value, the softer the hardness of the carbon fiber precursor strand. When evaluating deterioration over time, the carbon fiber precursor immediately after production (within 7 days after production) and the carbon fiber precursor stored at room temperature for 12 months after production were used. The closer the change rate of the strand hardness calculated from the following formula was to 0%, the more the deterioration of the strand hardness over time was suppressed. (Rate of change (%)) = ((Strand hardness of carbon fiber precursor after 12 months of storage at room temperature) - (Strand hardness of carbon fiber precursor immediately after production)) / (Strand hardness of carbon fiber precursor immediately after production) × 100 (formula)

[0117] <Scrub resistance> Using a TM type friction and holding force tester TM-200 (manufactured by Daiei Kagaku Seiki Co., Ltd.), a 50 g tension was applied to a carbon fiber precursor strand (24K) through three mirror-finished chrome-plated stainless steel needles arranged in a zigzag pattern and rubbed 1000 times (reciprocating motion speed 300 times / min). The state of the fuzzing of the carbon fiber precursor strand was visually judged according to the following criteria. When evaluating, the carbon fiber precursor immediately after production (within 7 days after production) and the carbon fiber precursor stored at room temperature for 12 months after production were used. ◎: No fuzzing is observed as before rubbing, and the scrub resistance is very good. ○: A few fuzzes are observed, and the scrub resistance is good. △: Slightly more fuzzing, and the scrub resistance is slightly inferior. ×: Considerable fuzzing, significant single-filament breakage is observed, and the scrub resistance is inferior.

[0118] <Carbon fiber strength> The measurement was carried out in accordance with the epoxy resin impregnated strand method specified in JIS-R-7608, and the average value of 10 measurements was taken as the carbon fiber strength (GPa). In the evaluation, the carbon fiber precursor immediately after production (within 7 days after production) and the carbon fiber precursor stored at room temperature for 12 months after production were used. In the evaluation of deterioration over time, carbon fibers produced using the carbon fiber precursor immediately after production (within 7 days after production) and carbon fibers produced using the carbon fiber precursor stored at room temperature for 12 months after production were used. The closer the change rate of the carbon fiber strength calculated from the following formula is to 0%, the more the deterioration over time of the carbon fiber precursor is suppressed. (Rate of change (%)) = ((Strength of carbon fiber produced using the carbon fiber precursor immediately after production) - (Strength of carbon fiber produced using the carbon fiber precursor stored at room temperature for 12 months)) / (Strength of carbon fiber produced using the carbon fiber precursor immediately after production) × 100 (formula)

[0119] <Evaluation of deterioration over time of carbon fiber precursor> Using the change rate of the strand hardness and the change rate of the carbon fiber strength of the above carbon fiber precursor, the determination was carried out according to the following criteria, and ◎ and ○ were regarded as passing. ◎: The change rate of the strand hardness is 40% or less, and the change rate of the carbon fiber strength is less than 5% ○: The change rate of the strand hardness exceeds 40%, and the change rate of the carbon fiber strength is less than 5% △: The change rate of the strand hardness is 40% or less, and the change rate of the carbon fiber strength is 5% or more ×: The change rate of the strand hardness exceeds 40%, and the change rate of the carbon fiber strength is 5% or more

[0120] [Example 1] Silicone a1 having an amino group, silicones b1 and b6 having a polyether group, aromatic compound c2-1-3, aliphatic compounds d2-2-1 and d2-2-2 having an oxyalkylene group, and water were mixed and emulsified in an aqueous system to prepare a treatment agent for a carbon fiber precursor with a non-volatile content concentration of 30% by weight. The weight ratio of silicone a1 having an amino group in the non-volatile content of the treatment agent was 60.0% by weight, the weight ratio of silicone b1 having a polyether group was 0.5% by weight, the weight ratio of b6 was 0.5% by weight, the weight ratio of aromatic compound c2-1-3 was 36% by weight, the weight ratio of aliphatic compound d2-2-1 having an oxyalkylene group was 2% by weight, and the weight ratio of d2-2-2 was 1% by weight. Subsequently, the prepared treatment agent was further diluted with water to obtain a diluted solution with a non-volatile content concentration of 3.0% by weight. The diluted solution was copolymerized with 97 mol% acrylonitrile and 3 mol% itaconic acid, and adhered to a raw material carbon fiber precursor of a carbon fiber precursor such that the imparting rate of the non-volatile content of the treatment agent was 1.0% by weight. A carbon fiber precursor was prepared through a stretching process (steam stretching, stretching ratio 2.1 times) (single fiber fineness 0.8 dtex, 24,000 filaments). This carbon fiber precursor was subjected to a flame retardant treatment in a flame retardant furnace at 250 °C for 60 minutes, and then fired in a carbonization furnace having a temperature gradient of 300 to 1400 °C in a nitrogen atmosphere to be converted into carbon fiber. The results of evaluating each characteristic value are shown in Table 1.

[0121] 〔Examples 2 to 24, Comparative Examples 1 to 9〕 In Example 1, a treatment agent for a carbon fiber precursor, a carbon fiber precursor, and carbon fiber were prepared and evaluated in the same manner as in Example 1, except that a treatment liquid was prepared to have the non-volatile content composition of the treatment agents shown in Tables 1 to 3. The results of evaluating each characteristic value are shown in Tables 1 to 3.

[0122] The details of the non-volatile content compositions in Tables 1 to 3 are as follows. <Silicone having an amino group (SA)> Silicone a1 having an amino group (viscosity at 25 °C: 250 mm 2 / s, amino equivalent 7600 g / mol, diamine type, side chain amino modified silicone) Silicone a2 having an amino group (viscosity at 25°C: 1500 mm 2 / s, amino equivalent: 3800 g / mol, diamine type, side-chain amino-modified silicone) Silicone a3 having an amino group (viscosity at 25°C: 20000 mm 2 / s, amino equivalent: 3600 g / mol, diamine type, side-chain amino-modified silicone) Silicone a4 having an amino group (viscosity at 25°C: 1700 mm 2 / s, amino equivalent: 3800 g / mol, monoamine type, side-chain amino-modified silicone) Silicone a5 having an amino group (viscosity at 25°C: 1300 mm 2 / s, amino equivalent: 1700 g / mol, diamine type, side-chain amino-modified silicone) Silicone a6 having an amino group (viscosity at 25°C: 10000 mm 2 / s, amino equivalent: 3600 g / mol, diamine type, side-chain amino-modified silicone) Silicone a7 having an amino group (viscosity at 25°C: 450 mm 2 / s, amino equivalent: 5700 g / mol, both-terminal amino-modified silicone) Silicone a8 having an amino group (viscosity at 25°C: 3300 mm 2 / s, amino equivalent: 1800 g / mol, side-chain amino polyether-modified silicone)

[0123] <Silicone (SB) having a polyether group> Note that EO / PO indicates the weight ratio of EO units to PO units contained in the silicone (SB) having a polyether group. Silicone b1 having a polyether group (viscosity at 25°C: 200 mm 2 / s, HLB: 16, EO / PO = 100 / 0, side-chain polyether-modified silicone) Silicone b2 having a polyether group (viscosity at 25°C: 920 mm 2 / s, HLB: 10, EO / PO = 70 / 30, side-chain polyether-modified silicone) Silicone b3 having a polyether group (viscosity at 25°C: 250 mm 2 / s, HLB: 8, EO / PO = 100 / 0, Side-chain polyether-modified silicone) Silicone b4 having a polyether group (viscosity at 25°C: 1300 mm 2 / s, HLB: 7, EO / PO = 60 / 40, Side-chain polyether-modified silicone) Silicone b5 having a polyether group (viscosity at 25°C: 2900 mm 2 / s, HLB: 6, EO / PO = 50 / 50, Side-chain polyether-modified silicone) Silicone b6 having a polyether group (viscosity at 25°C: 130 mm 2 / s, HLB: 4, EO / PO = 40 / 60, Side-chain polyether-modified silicone) Silicone b7 having a polyether group (viscosity at 25°C: 70 mm 2 / s, HLB: 1, EO / PO = 20 / 80, Side-chain alkyl polyether-modified silicone)

[0124] <Aromatic compound (C)> Aromatic compound c1-1-1 having an oxyalkylene group: Nonylphenol with 3 moles of oxyethylene groups added Aromatic compound c1-1-2 having an oxyalkylene group: Tribenzylphenol with 17 moles of oxyethylene groups added Aromatic compound c1-2-1 having an oxyalkylene group: Benzyl alcohol with 9 moles of oxyethylene groups added Aromatic compound c1-3-1 having an oxyalkylene group: 4,4'-Dihydroxy-2,2'-diphenylpropane with 4 moles of oxyethylene groups added Aromatic compound c1-3-2 having an oxyalkylene group: 4,4'-Dihydroxy-2,2'-diphenylpropane with 10 moles of oxyethylene groups added Aromatic compound c2-1-1 having an ester group: Ester compound obtained by condensing 2 moles of lauric acid with 1 mole of 4,4'-dihydroxy-2,2'-diphenylpropane Aromatic compound c2-1-2 having an ester group: An ester compound formed by condensing 1 mol of 4,4'-dihydroxy-2,2'-diphenylpropane with 2 moles of oxyethylene groups added and 2 moles of lauric acid Aromatic compound c2-1-3 having an ester group: An ester compound formed by condensing 1 mol of 4,4'-dihydroxy-2,2'-diphenylmethane with 2 moles of oxyethylene groups added and 2 moles of oleic acid Aromatic compound c2-2-1 having an ester group: An ester compound formed by condensing 3 moles of isodecyl alcohol and 1 mol of trimellitic acid Aromatic compound c2-3-1 having an ester group: An ester compound formed by condensing 1 mol of benzyl alcohol and 1 mol of benzoic acid

[0125] <Aliphatic compound (D) having an oxyalkylene group> Aliphatic compound d1-1 having an oxyalkylene group: A secondary alkyl ether having 12 to 14 carbon atoms with 5 moles of oxyethylene groups added Aliphatic compound d1-2 having an oxyalkylene group: A secondary alkyl ether having 12 to 14 carbon atoms with 9 moles of oxyethylene groups added Aliphatic compound d2-1―1 having an oxyalkylene group: Oleic acid with 6 moles of oxyethylene groups added Aliphatic compound d2-1―2 having an oxyalkylene group: Oleic acid with 9 moles of oxyethylene groups added Aliphatic compound d2-2―1 having an oxyalkylene group: Sorbitan monolaurate with 14 moles of oxyethylene groups added Aliphatic compound d2-2―2 having an oxyalkylene group: Sorbitan monolaurate with 35 moles of oxyethylene groups added

[0126] <Bronsted acid compound (E)> Bronsted acid compound e1: Acetic acid Bronsted acid compound e2: Phosphoric acid

[0127] [Table 1]

[0128]

Table 2

[0129]

Table 3

[0130] As can be seen from Tables 1 to 3, the treatment agents for carbon fiber precursors in Examples 1 to 24 contain a silicone compound (S) and an aromatic compound (C). The silicone compound (S) contains a silicone having an amino group (SA) and a silicone having a polyether group (SB). The aromatic compound (C) contains at least one selected from an aromatic compound having an oxyalkylene group (C1) and an aromatic compound having an ester group (C2). Since the proportion of the silicone compound (S) in the non-volatile matter is 65% by weight or less, when the carbon fiber precursor produced by applying the treatment agent was stored for a long period, deterioration of the carbon fiber precursor could be suppressed. On the other hand, since the treatment agents for carbon fiber precursors in Comparative Examples 1 to 9 are not the treatment agents for carbon fiber precursors of the present invention, when the carbon fiber precursor produced by applying the treatment agent was stored for a long period, deterioration of the carbon fiber precursor could not be suppressed.

Claims

1. A treatment agent for a carbon fiber precursor, containing a silicone compound (S) and an aromatic compound (C), wherein the silicone compound (S) contains a silicone having an amino group (SA) and a silicone having a polyether group (SB), the aromatic compound (C) contains at least one selected from an aromatic compound having an oxyalkylene group (C1) and an aromatic compound having an ester group (C2), and the proportion of the silicone compound (S) in the non-volatile matter is 65% by weight or less.

2. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the aromatic compound (C) contains an aromatic compound having an oxyalkylene group (C1).

3. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the aromatic compound (C) contains an aromatic compound having a bisphenol skeleton.

4. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the acid value of the treatment agent is 0.1 to 30 mgKOH / g.

5. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the HLB of the silicone having a polyether group (SB) is 4 to 16.

6. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the silicone having a polyether group (SB) includes a silicone in which the polyether group has an oxypropylene unit.

7. The treatment agent for a carbon fiber precursor according to Claim 1, wherein the proportion of the aromatic compound (C) in the non-volatile matter of the treatment agent is 35 to 90% by weight.

8. The treatment agent for a carbon fiber precursor according to Claim 1, containing an aliphatic compound (D) having an oxyalkylene group.

9. A carbon fiber precursor obtained by attaching the treatment agent for a carbon fiber precursor according to any one of Claims 1 to 8 to a raw material carbon fiber precursor of the carbon fiber precursor.

10. A method for producing a carbon fiber, including a flame-resistant treatment step of converting the carbon fiber precursor according to Claim 9 into a flame-resistant fiber, and a carbonization treatment step of carbonizing the flame-resistant fiber.

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