Treatment agent for manufacturing carbon fiber-containing nonwoven fabric, carbon fiber-containing nonwoven fabric, and method for manufacturing carbon fiber-containing nonwoven fabric.

Abstract

To provide: a treatment agent for producing a carbon fiber-containing non-woven fabric that can reduce breaking in carbon fibers; a carbon fiber-containing non-woven fabric; and a method for producing the carbon fiber-containing non-woven fabric.SOLUTION: The treatment agent for producing the carbon fiber-containing non-woven fabric contains an epoxy compound (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a treatment agent for manufacturing a carbon fiber-containing nonwoven fabric, a carbon fiber-containing nonwoven fabric to which such a treatment agent is attached, and a method for manufacturing a carbon fiber-containing nonwoven fabric using such a treatment agent.

Background Art

[0002] Generally, carbon fibers are widely used in various fields such as building materials and transportation equipment as carbon fiber composite materials combined with matrix resins such as epoxy resins or as flame retardant / flameproof materials. For example, carbon fibers are produced through a process of spinning acrylic fibers, stretching the fibers, a flame resistance improvement process, and a carbonization process as carbon fiber precursors.

[0003] In addition to woven fabrics, carbon fibers may be formed into nonwoven fabrics obtained using a roller card (carding machine) and used. When manufacturing a nonwoven fabric, a treatment for attaching a nonwoven fabric treatment agent to the surface of the fibers may be performed from the viewpoint of imparting various properties such as card passing properties to the raw fibers. Conventionally, a treatment agent disclosed in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when carbon fibers to which a treatment agent is applied pass through a carding machine, the carbon fibers may break. For a treatment agent for manufacturing a carbon fiber-containing nonwoven fabric, further improvement in the effect of reducing the breakage of carbon fibers has been demanded.

Means for Solving the Problems

[0006] As a result of research conducted to solve the above-mentioned problems, the present inventors have found that a composition containing epoxy compound (A) is preferable for a treatment agent for manufacturing carbon fiber-containing nonwoven fabrics. The following describes various methods for solving the above problems.

[0007] The treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to Embodiment 1 is a treatment agent for manufacturing carbon fiber-containing nonwoven fabric containing an epoxy compound (A) and the following ester compound (C), wherein the epoxy compound (A) has at least one selected from bisphenol A, bisphenol F, and diaminediphenylmethane as its main skeleton, and the content of the ester compound (C) in the nonvolatile content of the treatment agent is 3 to 60% by mass. It is used as a raw material for carbon fibers in nonwoven fabrics obtained using a carding machine. It is characterized by the following.

[0008] Ester compounds (C): Ester compounds consisting of a monohydric aliphatic alcohol and a monohydric carboxylic acid. Embodiment 2 is a treatment agent for manufacturing carbon fiber-containing nonwoven fabric as described in Embodiment 1, wherein the epoxy compound (A) comprises at least one selected from a bisphenol A skeleton and a bisphenol F skeleton.

[0009] Embodiment 3 is a treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to Embodiment 1 or 2, wherein the content of the epoxy compound (A) in the nonvolatile components of the treatment agent is 5 to 90% by mass. Embodiment 4 is a treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to any one of Embodiments 1 to 3, further containing a nonionic surfactant (B), wherein the content ratio of the nonionic surfactant (B) in the nonvolatile content of the treatment agent is 5 to 60% by mass.

[0010] Embodiment 5 is a treatment agent for manufacturing carbon fiber-containing nonwoven fabric as described in Embodiment 1, further comprising a nonionic surfactant (B), wherein, when the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100% by mass, the epoxy compound (A) is contained in a proportion of 5 to 90% by mass, the nonionic surfactant (B) in a proportion of 5 to 60% by mass, and the ester compound (C) in a proportion of 5 to 50% by mass.

[0011] The carbon fiber-containing nonwoven fabric of embodiment 6 is characterized in that it has the treatment agent described in any one of embodiments 1 to 5 attached to it. The method for producing a carbon fiber-containing nonwoven fabric according to Embodiment 7 is a step of applying the treatment agent described in any one of Embodiments 1 to 5 to the short carbon fibers. , and the process of passing through the card machine It is characterized by including. [Effects of the Invention]

[0012] According to the present invention, the breakage of carbon fibers treated with a processing agent for manufacturing carbon fiber-containing nonwoven fabrics can be reduced. [Modes for carrying out the invention]

[0013] <First Embodiment> The following describes a first embodiment of the treatment agent for manufacturing carbon fiber-containing nonwoven fabrics of the present invention (hereinafter referred to as the treatment agent). The treatment agent of this embodiment contains the following epoxy compound (A) and ester compound (C), and may further contain a nonionic surfactant (B).

[0014] (Epoxy compound (A)) Epoxy compound (A) is a compound having an epoxy group in its molecule. Epoxy compound (A) may be either a monoepoxy compound having one epoxy group in its molecule, or a polyfunctional epoxy compound having two or more epoxy groups.

[0015] Furthermore, examples of main chains include diphenylmethane, and more specifically, bisphenol. Specific examples of bisphenols include bisphenol A, AP, AF, B, BP, C, E, F, G, M, S, P, PH, TMC, Z, etc. Among these, epoxy compounds (A) having a bisphenol A skeleton and bisphenol F skeleton are preferred from the viewpoint of further reducing carbon fiber bending.

[0016] In the present invention, epoxy compound (A) is used that has at least one selected from bisphenol A, bisphenol F, and diaminediphenylmethane as its main skeleton. Compounds other than epoxy compound (A) of the present invention are provided below as reference examples.

[0017] Specific examples of epoxy compounds (A) include amine-type epoxy compounds such as polymers of polyoxyalkylene-added p-tert-butylphenol monoglycidyl ether, bisphenol A diglycidyl ether, resorcinol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, alkyl glycidyl ether, polyoxyalkylene-added alkyl glycidyl ether, phenyl glycidyl ether, polyoxyalkylene-added phenyl glycidyl ether, triglycidylamine, tetraglycidylamine, etc.

[0018] In addition, a commercially available product may be used as the epoxy compound (A). Specific examples of commercially available products include, for example, jER828 (manufactured by Mitsubishi Chemical Corporation), jER834 (manufactured by Mitsubishi Chemical Corporation), jER1001 (manufactured by Mitsubishi Chemical Corporation), jER1002 (manufactured by Mitsubishi Chemical Corporation), Epotote YD-128 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Epotote YD-011 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Epotote YD-012 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Sumiepoxy ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.), EPICRON N-660 (manufactured by DIC Corporation), and the like.

[0019] These epoxy compounds (A) may be used alone or in appropriate combination of two or more. The content ratio of the epoxy compound (A) in the non-volatile matter of the treatment agent is preferably 3 to 100% by mass, more preferably 5 to 90% by mass. By defining it within such a range, the effects of the present invention can be further improved. In addition, ranges arbitrarily combining the above upper and lower limits are also assumed. The non-volatile matter refers to the treatment agent after sufficient removal of volatile components by heat treatment at 105°C for 2 hours. Hereinafter, the definition of non-volatile matter shall adopt the same conditions.

[0020] (Nonionic surfactant (B)) The treatment agent may further contain a nonionic surfactant (B). When the nonionic surfactant (B) is contained in the treatment agent, the strength of the non-woven fabric obtained from the carbon fiber to which the treatment agent is applied is improved.

[0021] Examples of nonionic surfactants (B) include compounds having a (poly)oxyalkylene structure obtained by adding alkylene oxide to alcohols or carboxylic acids, ether ester compounds having a (poly)oxyalkylene structure obtained by adding alkylene oxide to ester compounds of carboxylic acids and polyhydric alcohols, compounds obtained by adding alkylene oxide to natural oils and fats or compounds obtained by esterifying such compounds with carboxylic acids, amine compounds such as compounds having a (poly)oxyalkylene structure obtained by adding alkylene oxide to primary organic amines, compounds having a (poly)oxyalkylene structure obtained by adding alkylene oxide to fatty acid amides, amide compounds obtained by condensing amine compounds and carboxylic acids, and partial ester compounds of carboxylic acids and polyhydric alcohols, etc.

[0022] Specific examples of the alcohols used as raw materials for the nonionic surfactant (B) include, for example, (1) linear alkyl alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, heptacosanol, octacosanol, nonacosanol, triacontanol, etc., (2) branched alkyl alcohols such as isopropanol, isobutanol, isohexanol, 2-ethylhexanol, isononanol, isodecanol, isododecanol, isotridecanol, isotetradecanol, isotriacontanol, isohexadecanol, isoheptadecanol, isooctadecanol, isononadecanol, isoeicosanol, isoheneicosanol, isodocosanol, isotricosanol, isotetracosanol, isopentacosanol, isohexacosanol, isoheptacosanol, isooctacosanol, isononacosanol, isopentadecanol, etc., (3) linear alkenyl alcohols such as tetradecenol, hexadecenol, heptadecenol, octadecenol, nonadecenol, etc., (4) branched alkenyl alcohols such as isohexadecenol, isooctadecenol, etc., (5) cyclic alkyl alcohols such as cyclopentanol, cyclohexanol, etc., (6) aromatic alcohols such as phenol, nonylphenol, benzyl alcohol, monostyrenated phenol, distyrenated phenol, tristyrenated phenol, etc.

[0023] Specific examples of carboxylic acids used as raw materials for nonionic surfactants (B) include, for example, (1) linear alkyl carboxylic acids such as octic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid, and docosanoic acid; (2) branched alkyl carboxylic acids such as 2-ethylhexanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isohexadecanoic acid, and isooctadecanoic acid; (3) linear alkenyl carboxylic acids such as octadecenoic acid, octadecadienoic acid, and octadecatrienoic acid; (4) aromatic carboxylic acids such as benzoic acid; and (5) hydroxycarboxylic acids such as ricinoleic acid.

[0024] As the alkylene oxide used as a raw material to form the (poly)oxyalkylene structure of the nonionic surfactant (B), alkylene oxides having 2 to 4 carbon atoms are preferred. Specific examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide. The number of moles of alkylene oxide to be added is set as appropriate, but is preferably 0.1 moles to 150 moles, more preferably 1 mole to 100 moles, and even more preferably 2 moles to 50 moles. Ranges arbitrarily combining the above upper and lower limits are also conceivable. The number of moles of alkylene oxide to be added indicates the number of moles of alkylene oxide per mole of the compound to be added in the raw materials. One type of alkylene oxide may be used alone, or two or more types of alkylene oxides may be used in appropriate combinations. When two or more types of alkylene oxide are applied, their addition methods may be block addition, random addition, or a combination of block addition and random addition, and are not particularly limited.

[0025] Specific examples of polyhydric alcohols used as raw materials for nonionic surfactants (B) include, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, glycerin, diglycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, trimethylolpropane, sorbitan, pentaerythritol, sorbitol, and the like.

[0026] Specific examples of aliphatic amines or primary organic amines used as raw materials for nonionic surfactants (B) include, for example, methylamine, ethylamine, butylamine, octylamine, laurylamine, octadecylamine (stearylamine), octadecenylamine, and coconut amine.

[0027] Specific examples of fatty acid amides used as raw materials for nonionic surfactants (B) include, for example, octylic acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, behenic acid amide, lignoceric acid amide, amide of fatty acid and diethanolamine, and amide of fatty acid and ethyleneamine.

[0028] These nonionic surfactants (B) may be used individually or in combination of two or more as appropriate. In the nonvolatile components of the treatment agent, the content of nonionic surfactant (B) is preferably 3 to 70% by mass, and more preferably 5 to 60% by mass. By specifying the content within this range, the strength of the nonwoven fabric obtained from carbon fibers treated with the treatment agent is improved. It should be noted that ranges arbitrarily combining the above upper and lower limits are also conceivable.

[0029] (Ester compound (C)) The ester compound (C) used as the treatment agent in this embodiment is an ester compound consisting of a monohydric aliphatic alcohol and a monohydric carboxylic acid. By applying this ester compound (C), the strength of the nonwoven fabric obtained from carbon fibers treated with the treatment agent is improved.

[0030] The monovalent carboxylic acid constituting the ester compound (C) may be either a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. Furthermore, it may be linear or have a branched chain structure.

[0031] Specific examples of saturated aliphatic carboxylic acids include, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid (caproic acid), octicic acid (2-ethylhexanoic acid), octanoic acid (caprylic acid), nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), isooctadecanoic acid (isostearic acid), eicosanoic acid (arachidic acid), docosanic acid (behenic acid), and tetracosanoic acid.

[0032] Specific examples of unsaturated aliphatic carboxylic acids include, for example, crotonic acid, myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, eicosenoic acid, linoleic acid, alpha-linolenic acid, gamma-linolenic acid, and arachidonic acid.

[0033] Specific examples of monohydric aliphatic alcohols include the alcohols used as raw materials for the nonionic surfactant (B) mentioned above, which are examples of monohydric aliphatic alcohols. These ester compounds (C) may be used individually or in combination of two or more.

[0034] In the non-volatile components of the treatment agent, the content of ester compound (C) is 3 to 60% by mass, preferably 5 to 50% by mass. By specifying the content within this range, the strength of the nonwoven fabric obtained from carbon fibers treated with the treatment agent is improved. It should be noted that ranges arbitrarily combining the above upper and lower limits are also conceivable.

[0035] In the treatment agent, if the total content of epoxy compound (A), nonionic surfactant (B), and ester compound (C) is taken as 100% by mass, it is preferable that the epoxy compound (A) is contained in a ratio of 5 to 90% by mass, the nonionic surfactant (B) in a ratio of 5 to 60% by mass, and the ester compound (C) in a ratio of 5 to 50% by mass. By specifying the content within this range, the effects of the present invention can be further improved. It should be noted that a range obtained by arbitrarily combining the above upper and lower limits is also conceivable.

[0036] <Second Embodiment> Next, a second embodiment of the carbon fiber-containing nonwoven fabric (hereinafter simply referred to as "nonwoven fabric") according to the present invention will be described. In this embodiment, the nonwoven fabric has the treatment agent of the first embodiment attached to it. The nonwoven fabric of this embodiment is manufactured by first attaching the treatment agent of the first embodiment to the carbon fibers, and then performing a web formation process by carding. There are no particular restrictions on the amount of treatment agent attached to the nonwoven fabric, but preferably the amount of treatment agent (solvent-free) attached to the nonwoven fabric is 0.01 to 10% by mass, more preferably 0.1 to 2% by mass.

[0037] There are no particular restrictions on the type of carbon fiber that constitutes the nonwoven fabric, but examples include PAN-based fibers obtained from acrylic fibers, pitch-based fibers obtained from pitch, recycled carbon fibers extracted from carbon fiber composite materials by chemical decomposition / thermal decomposition methods, polyester fibers, polyethylene resin, phenolic resin, cellulose resin, lignin resin, etc., as raw materials. For example, when acrylic fibers are used, it is preferable that the acrylic fibers consist mainly of polyacrylonitrile obtained by copolymerizing at least 90 mol% or more of acrylonitrile with 10 mol% or less of a flame-retardant promoting component. As the flame-retardant promoting component, for example, a vinyl group-containing compound copolymerizable with acrylonitrile can be suitably used. There are no particular restrictions on the fineness of the single fibers of the raw material fibers, but from the viewpoint of balancing performance and manufacturing costs, it is preferably 0.1 to 2.0 dTex. There are also no particular restrictions on the number of single fibers that constitute the fiber bundle of the raw material fibers, but from the viewpoint of balancing performance and manufacturing costs, it is preferably 1,000 to 96,000.

[0038] The carbon fiber manufacturing method of this embodiment first involves obtaining the raw fibers described above, followed by a spinning process in which the fibers are spun into yarn. Next, a flame-retardant treatment process is performed in which the fiber bundles produced in the spinning process are converted into flame-retardant fibers in an oxidizing atmosphere at 200 to 300°C, preferably 230 to 270°C. If carbon fibers are to be obtained further, a carbonization treatment process is performed in which the flame-retardant fibers are further carbonized in an inert atmosphere at 300 to 2000°C, preferably 300 to 1300°C. The carbonization treatment process may be performed immediately following the flame-retardant treatment process.

[0039] As described above, the method for manufacturing the nonwoven fabric of this embodiment first involves a step of attaching the treatment agent of the first embodiment to the carbon fibers. A known method can be appropriately adopted for attaching the treatment agent to the carbon fibers. For example, methods that are generally used in industry, such as immersion lubrication, roller immersion, roller contact, spray, papermaking, and guided lubrication using a metering pump, can be applied.

[0040] Examples of the form in which the treatment agent of the first embodiment is applied to the fibers include an organic solvent solution and an aqueous solution. The treatment agent is preferably applied to the carbon fibers in the form of an aqueous emulsion. The length of the fibers to which the treatment agent is applied is not particularly limited, and examples include short fibers generally called staples and long fibers generally called filaments. In addition, carbon fibers made by mixing and blending two or more different staples may be used. Examples of synthetic fibers to be blended include polyamide fibers such as nylon 6, nylon 66, polyamide 9T, and polyamide 10, polypropylene, and polyethylene. The ratio of synthetic fibers to carbon fibers when blending is not particularly limited, but is preferably 10:90 to 90:10, and more preferably 20:80 to 80:20. When blending, the treatment agent may be applied before or after blending the carbon fibers and synthetic fibers.

[0041] Next, the carbon fibers can be dried to remove the solvent, such as water, contained in the treatment agent solution, thereby obtaining carbon fibers to which the treatment agent has adhered. For this drying process, methods such as using hot air, hot plates, rollers, or various infrared heaters as heat transfer fluids can be employed.

[0042] Next, a web formation process is carried out. The web formation process involves carding the carbon fibers to which the above-mentioned treatment agent has been applied to produce a web made of nonwoven fabric. Carding can be performed using a known carding machine. Examples include flat cards, combination cards, roller cards, etc.

[0043] The effects of the treatment agent and nonwoven fabric of this embodiment will be explained. (1) The treatment agent in this embodiment is composed of epoxy compound (A). Therefore, when passing through the carding machine, the bending of carbon fibers to which the treatment agent has been applied can be reduced. In addition, the strength of the nonwoven fabric obtained from carbon fibers to which the treatment agent has been applied can be improved.

[0044] (2) If the treatment agent contains a predetermined amount of a nonionic surfactant (B) or an ester compound (C), the strength of the nonwoven fabric obtained from the carbon fibers to which the treatment agent has been applied can be further improved. The above embodiment may be modified as follows. The above embodiment and the following modifications can be combined and implemented to the extent that they do not contradict each other technically.

[0045] The treatment agent in the above embodiment may further contain components commonly used in treatment agents, such as stabilizers, antistatic agents, binders, antioxidants, and ultraviolet absorbers, to the extent that they do not impede the effects of the present invention. [Examples]

[0046] The following examples illustrate the structure and effects of the present invention in more detail, but the present invention is not limited to these examples. In the following examples and comparative examples, "parts" refers to parts by mass, and "%" refers to mass percent.

[0047] Test category 1 (Preparation of treatment agent) As shown in Table 1, each example of treatment agent was prepared by gradually adding water or an organic solvent while stirring an epoxy compound (A), a nonionic surfactant (B), an ester compound (C), and other components (D) until the solid content concentration reached 30%.

[0048] [Table 1]

[0049] [Table 2]

[0050] [Table 3]

[0051] Test category 2 (Manufacturing of carbon fiber nonwoven fabrics) Carbon fiber nonwoven fabric was manufactured using the treatment agent prepared in test category 1. The aqueous or organic solvent solutions of each prepared treatment agent were further diluted with water to obtain 1-4% aqueous solutions of each treatment agent. These aqueous solutions were applied to 45 mm long carbon staple fibers using a spray oiling method. The fibers were then dried in a hot air dryer at 105°C for 60 minutes to obtain treated carbon staple fibers with the treatment agent applied. The obtained treated carbon staple fibers were conditioned overnight at 25°C in a 65% RH atmosphere and then subjected to evaluation. In Example 47, etc., the synthetic fibers listed in the table were blended in the specified proportions.

[0052] Ten kg of the processed carbon staple fibers obtained above were subjected to a carding process with a two-lobe condenser. The carding process was carried out under the following conditions: spinning speed = 18.0 m / min, spinning weight = 1 g / m, and kneading cycles = 30 times / inch, in an atmosphere of 25°C × 65% RH. A carbon fiber nonwoven fabric was obtained as a web.

[0053] Test category 3 (Suppression of carbon fiber breakage) The degree of carbon fiber bending was evaluated by measuring the percentage change in carbon fiber length before and after carding. Short fibers, all aligned to 50 mm in length, were passed through a card, and the length of each short fiber was measured for n=50 samples. The average value was calculated as (average length after carding / average length before carding) × 100, and evaluated according to the following criteria.

[0054] • Evaluation criteria for suppressing carbon fiber breakage ◎(Good): 90% or more ○ (Acceptable): 70% or more, less than 90% × (Not acceptable): Less than 70% Test category 4 (Strength of manufactured web) The strength of the manufactured web was evaluated by gripping and pulling the obtained web and measuring the magnification at which it broke. Using the manufactured web, a tensile strength tester was used to stretch it for 1 minute at a gripping length of 10 cm and a tensile speed of 10 cm / min, and it was confirmed whether or not the web broke during this time. The evaluation was performed according to the following criteria.

[0055] • Criteria for evaluating the strength of manufactured websites ◎◎ (Excellent): If the web does not disconnect during stretching. ◎(Good): If the web connection is interrupted during extension, between 50 and 60 seconds. ○(OK): If the web connection is interrupted during the extension process, between 40 and 50 seconds. × (Not allowed): If the web connection is lost in less than 40 seconds during the extension process. As is clear from the evaluation results of each example for each comparative example in the table above, the treatment agent of the present invention can reduce the bending of carbon fibers treated with the agent when they pass through the card. Furthermore, it can improve the strength of the web obtained from carbon fibers treated with the agent.

Claims

1. A treatment agent for manufacturing carbon fiber-containing nonwoven fabrics, comprising an epoxy compound (A) and the following ester compound (C), The epoxy compound (A) has at least one selected from bisphenol A, bisphenol F, and diaminediphenylmethane as its main skeleton. A treatment agent for manufacturing carbon fiber-containing nonwoven fabrics, characterized in that the content of the ester compound (C) in the nonvolatile components of the treatment agent is 3 to 60% by mass, and it is used for carbon fibers, which are raw materials for nonwoven fabrics obtained using a carding machine. Ester compounds (C): Ester compounds consisting of a monohydric aliphatic alcohol and a monohydric carboxylic acid.

2. The treatment agent for producing carbon fiber-containing nonwoven fabric according to claim 1, wherein the epoxy compound (A) is at least one selected from a bisphenol A skeleton and a bisphenol F skeleton.

3. The treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to claim 1, wherein the content of the epoxy compound (A) in the nonvolatile components of the treatment agent is 5 to 90% by mass.

4. Furthermore, it contains a nonionic surfactant (B), The treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to claim 1, wherein the content of the nonionic surfactant (B) in the nonvolatile components of the treatment agent is 5 to 60% by mass.

5. Furthermore, it contains a nonionic surfactant (B), The treatment agent for manufacturing carbon fiber-containing nonwoven fabric according to claim 1, wherein, when the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100% by mass, the epoxy compound (A) is contained in a proportion of 5 to 90% by mass, the nonionic surfactant (B) in a proportion of 5 to 60% by mass, and the ester compound (C) in a proportion of 5 to 50% by mass.

6. A carbon fiber-containing nonwoven fabric characterized by having the treatment agent described in any one of claims 1 to 5 attached to it.

7. A method for producing a carbon fiber-containing nonwoven fabric, comprising the steps of: attaching a treatment agent according to any one of claims 1 to 5 to short carbon fibers; and passing the fabric through a carding machine.

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