JP7500104B1 - Treatment agent for producing carbon fiber-containing nonwoven fabric, carbon fiber-containing nonwoven fabric, and method for producing carbon fiber-containing nonwoven fabric - Google Patents

Abstract

The present invention provides a treatment agent for producing a carbon fiber-containing nonwoven fabric, which can reduce breakage of carbon fibers, a carbon fiber-containing nonwoven fabric, and a method for producing a carbon fiber-containing nonwoven fabric. The treatment agent for producing a carbon fiber-containing nonwoven fabric of the present invention is characterized by containing an epoxy compound (A). [Selected Figures] None

Description

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

In general, 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 and fire-resistant materials. For example, carbon fibers are produced through a process of spinning acrylic fibers as a carbon fiber precursor, a process of drawing the fibers, a flame-retardant process, and a carbonization process.

Carbon fibers may be used in the form of woven fabrics or nonwoven fabrics obtained using a roller card (carding machine). When producing nonwoven fabrics, a treatment may be applied to the surface of the raw fiber to impart various properties such as carding properties to the fiber. A treatment disclosed in Patent Document 1 is known.

Patent No. 6184668

However, when the carbon fibers to which the treatment agent was applied passed through a carding machine, the carbon fibers sometimes broke. There was a demand for further improvements in the effect of reducing breakage of carbon fibers in treatment agents used in the production of carbon fiber-containing nonwoven fabrics.

As a result of research aimed at solving the above problems, the present inventors have found that a treatment agent for producing a carbon fiber-containing nonwoven fabric containing an epoxy compound (A) is preferably used.
Various aspects for solving the above problems will be described below.

The treatment agent for producing a carbon fiber-containing nonwoven fabric of Aspect 1 is a treatment agent for producing a carbon fiber-containing nonwoven fabric, comprising an epoxy compound (A) , a nonionic surfactant (B) , and an ester compound (C) , characterized in that the content of the epoxy compound (A) in the nonvolatile matter of the treatment agent is 5 mass% or more and 60 mass% or less, the content of the ester compound (C) is 5 to 50 mass%, and the epoxy compound (A) has at least one compound selected from bisphenol A, bisphenol F, and diaminodiphenylmethane as a main skeleton.

Ester compound (C): An ester compound consisting of a monohydric aliphatic alcohol and a monobasic carboxylic acid.
The treatment agent for producing a carbon fiber-containing nonwoven fabric of Aspect 2 contains an epoxy compound (A) , a nonionic surfactant (B) , and an ester compound (C) , characterized in that the content of the nonionic surfactant (B) in the nonvolatile matter of the treatment agent is 30 mass % or more and 60 mass % or less , the content of the ester compound (C) is 5 to 40 mass %, and the epoxy compound (A) has at least one compound selected from bisphenol A and bisphenol F as a main skeleton.

Ester compound (C): An ester compound consisting of a monohydric aliphatic alcohol and a monobasic carboxylic acid.
In a third aspect, in the treating agent for producing a carbon fiber-containing nonwoven fabric according to the first aspect, the epoxy compound (A) has at least one selected from a bisphenol A skeleton and a bisphenol F skeleton .

In a fourth aspect, in the treating agent for producing a carbon fiber-containing nonwoven fabric according to the second aspect, the content of the epoxy compound (A) in the non-volatile matter of the treating agent is 5 to 60 mass %.
Aspect 5 is the treating agent for producing a carbon fiber-containing nonwoven fabric according to Aspect 1 or 3, in which the content of the nonionic surfactant (B) in the nonvolatile matter of the treating agent is 5 to 60 mass %.

Aspect 6 is the treatment agent for producing a carbon fiber-containing nonwoven fabric according to any one of Aspects 1, 3, and 5 , wherein the treatment agent contains the epoxy compound (A) in an amount of 5 to 90 mass%, the nonionic surfactant (B) in an amount of 5 to 60 mass%, and the ester compound (C) in an amount of 5 to 50 mass%, assuming that the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100 mass% .

Aspect 7 is the treatment agent for producing a carbon fiber-containing nonwoven fabric according to Aspect 2 or 4 , wherein the treatment agent contains the epoxy compound (A) in an amount of 5 to 60 mass%, the nonionic surfactant (B) in an amount of 30 to 60 mass%, and the ester compound (C) in an amount of 5 to 50 mass%, assuming that the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100 mass% .

The carbon fiber-containing nonwoven fabric of Aspect 8 is characterized in that the treating agent according to any one of Aspects 1 to 7 is adhered thereto.
A method for producing a carbon fiber-containing nonwoven fabric according to Aspect 9 is characterized by comprising a step of adhering the treating agent according to any one of Aspects 1 to 7 to short carbon fibers.

According to the present invention, it is possible to reduce breakage of carbon fibers to which a treatment agent for producing carbon fiber-containing nonwoven fabric has been applied.

First Embodiment
Hereinafter, a first embodiment of the treating agent for producing a carbon fiber-containing nonwoven fabric of the present invention (hereinafter, referred to as the treating agent) will be described. The treating agent of this embodiment contains the following epoxy compound (A) and nonionic surfactant (B), and further contains an ester compound (C).

(Epoxy compound (A))
The epoxy compound (A) is a compound having an epoxy group in the molecule. The epoxy compound (A) may be either a monoepoxy compound having one epoxy group in the molecule or a multifunctional epoxy compound having two or more epoxy groups in the molecule.

The main chain may be, for example, diphenylmethane, more specifically, bisphenol. Specific examples of bisphenol include bisphenol A, AP, AF, B, BP, C, E, F, G, M, S, P, PH, TMC, and Z. Among these, from the viewpoint of further reducing the breakage of carbon fibers, it is preferable that the epoxy compound (A) has a bisphenol A skeleton and a bisphenol F skeleton.

In the present invention, the epoxy compound (A) is a compound containing a diphenylmethane skeleton as the main skeleton. Examples of compounds containing a diphenylmethane skeleton as the main skeleton include compounds containing at least one skeleton selected from a bisphenol A skeleton, a bisphenol F skeleton, a diaminodiphenylmethane skeleton, and a cresol novolac skeleton. Hereinafter, compounds other than the epoxy compound (A) of the present invention are provided as reference examples.

Specific examples of epoxy compounds (A) include amine-type epoxy compounds such as 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, and other polymers.

In addition, commercially available products may be used as the epoxy compound (A). Specific examples of commercially available products include jER828 (manufactured by Mitsubishi Chemical Corporation), jER834 (manufactured by Mitsubishi Chemical Corporation), jER1001 (manufactured by Mitsubishi Chemical Corporation), jER1002 (manufactured by Mitsubishi Chemical Corporation), Epotohto YD-128 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Epotohto YD-011 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), Epotohto 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.

These epoxy compounds (A) may be used alone or in appropriate combination of two or more.
The content of the epoxy compound (A) in the non-volatile content of the treatment agent is, for example, 3 to 100% by mass , or 5 to 90% by mass. By specifying the content within such ranges, the effects of the present invention can be further improved. Any range combining the above upper and lower limits is also envisioned. The non-volatile content refers to the treatment agent that has been heat-treated at 105°C for 2 hours to thoroughly remove volatile components. Hereinafter, the definition of non-volatile content will adopt the same conditions.

(Nonionic Surfactant (B))
The treatment agent may further contain a nonionic surfactant (B). By including the nonionic surfactant (B) in the treatment agent, the strength of the nonwoven fabric obtained from the carbon fibers to which the treatment agent has been applied is improved.

Examples of nonionic surfactants (B) include compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to alcohols or carboxylic acids, ether/ester compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to ester compounds of carboxylic acids and polyhydric alcohols, compounds in which alkylene oxides are added to natural fats and oils or compounds in which such compounds are esterified with carboxylic acids, amine compounds such as compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to primary organic amines, compounds having a (poly)oxyalkylene structure in which alkylene oxides are added to fatty acid amides, amide compounds in which amine compounds and carboxylic acids are condensed, partial ester compounds of carboxylic acids and polyhydric alcohols, etc.

Specific examples of 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, and triacontanol; (2) isopropanol, isobutanol, isohexanol, 2-ethylhexanol, isononanol, isodecanol, isododecanol, isotridecanol, isotetradecanol, isotriacontanol, and isoheptadecanol; (3) branched alkyl alcohols such as tetradecenol, hexadecanol, heptadecanol, octadecanol, isononadecanol, isoeicosanol, isoheneicosanol, isodocosanol, isotricosanol, isotetracosanol, isopentacosanol, isohexacosanol, isoheptacosanol, isooctacosanol, isononacosanol, and isopentadecanol; (4) branched alkenyl alcohols such as isohexadecenol and isooctadecenol; (5) cyclic alkyl alcohols such as cyclopentanol and cyclohexanol; and (6) aromatic alcohols such as phenol, nonylphenol, benzyl alcohol, monostyrenated phenol, distyrenated phenol, and tristyrenated phenol.

Specific examples of carboxylic acids used as raw materials for the nonionic surfactant (B) include (1) linear alkyl carboxylic acids such as octylic 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.

As the alkylene oxide used as a raw material for forming the (poly)oxyalkylene structure of the nonionic surfactant (B), an alkylene oxide having 2 to 4 carbon atoms is preferred. Specific examples of alkylene oxide include, for example, ethylene oxide, propylene oxide, and butylene oxide. The number of moles of alkylene oxide added is set appropriately, but is preferably 0.1 to 150 moles, more preferably 1 to 100 moles, and even more preferably 2 to 50 moles. Any combination of the above upper and lower limits is also possible. The number of moles of alkylene oxide added indicates the number of moles of alkylene oxide per mole of the compound to be added in the raw material. As the alkylene oxide, one type of alkylene oxide may be used alone, or two or more types of alkylene oxides may be used in appropriate combination. When two or more types of alkylene oxide are used, the addition form may be any of block addition, random addition, and a combination of block addition and random addition, and is not particularly limited.

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

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

Specific examples of fatty acid amides used as raw materials for the nonionic surfactant (B) include octyl acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, behenic acid amide, lignoceric acid amide, amides of fatty acids and diethanolamine, and amides of fatty acids and ethyleneamine.

These nonionic surfactants (B) may be used alone or in appropriate combination of two or more kinds.
The content of the nonionic surfactant (B) in the nonvolatile matter of the treatment agent is, for example , 3 to 70 mass % , or 5 to 60 mass %. By specifying the content within such a range, the strength of the nonwoven fabric obtained from the carbon fiber to which the treatment agent is applied is improved. Note that any combination of the above upper and lower limits is also envisioned.

(Ester Compound (C))
The ester compound (C) used in the treatment agent of this embodiment is an ester compound composed of a monohydric aliphatic alcohol and a monovalent carboxylic acid. By using this ester compound (C), the strength of the nonwoven fabric obtained from the carbon fiber to which the treatment agent is applied is improved.

The monovalent carboxylic acid constituting the ester compound (C) may be a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. In addition, it may be a straight-chain or branched-chain structure.

Specific examples of saturated aliphatic carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid (caproic acid), octylic 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), docosanoic acid (behenic acid), and tetracosanoic acid.

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

Specific examples of the monohydric aliphatic alcohol include the specific examples of the monohydric aliphatic alcohols among the alcohols used as raw materials for the nonionic surfactant (B) described above.
These ester compounds (C) may be used alone or in combination of two or more.

The content of the ester compound (C) in the non-volatile matter of the treatment agent is, for example , 3 to 60 mass % , or 5 to 50 mass %. By specifying the content within such a range, the strength of the nonwoven fabric obtained from the carbon fiber to which the treatment agent is applied is improved. Note that ranges that combine the above upper and lower limits in any way are also envisioned.

In the treatment agent, if the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is taken as 100% by mass, it is preferable that the epoxy compound (A) is contained in an amount of 5 to 90% by mass, the nonionic surfactant (B) is contained in an amount of 5 to 60% by mass, and the ester compound (C) is contained in an amount of 5 to 50% by mass. By specifying the content ratios in such a range, the effect of the present invention can be further improved. Note that ranges that combine the above upper and lower limits in any desired manner are also contemplated.

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 the nonwoven fabric of this embodiment, the treatment agent of the first embodiment is adhered to the nonwoven fabric. The nonwoven fabric of this embodiment is manufactured by first carrying out a step of adhering the treatment agent of the first embodiment to carbon fibers, and then carrying out a web formation step by carding. There is no particular restriction on the amount of treatment agent adhered to the nonwoven fabric, but the treatment agent (not including the solvent) is preferably adhered to the nonwoven fabric in an amount of 0.01 to 10 mass %, more preferably 0.1 to 2 mass %.

The type of carbon fiber constituting the nonwoven fabric is not particularly limited, 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 or thermal decomposition, polyester fibers, carbon fibers obtained from polyethylene resins, phenolic resins, cellulose resins, lignin resins, etc. For example, when acrylic fibers are used, the acrylic fibers are preferably composed of fibers mainly composed of polyacrylonitrile obtained by copolymerizing at least 90 mol% or more of acrylonitrile and 10 mol% or less of a flame retardant promoting component. As the flame retardant promoting component, for example, a vinyl group-containing compound that is copolymerizable with acrylonitrile can be suitably used. There is no particular limit to the single fiber fineness of the raw fiber, but from the viewpoint of the balance between performance and production cost, it is preferably 0.1 to 2.0 dTex. In addition, there is no particular limit to the number of single fibers constituting the fiber bundle of the raw fiber, but from the viewpoint of the balance between performance and production cost, it is preferably 1,000 to 96,000.

In the method for producing carbon fiber of this embodiment, first, the raw fiber described above is obtained, and then a spinning process is carried out to spin the raw fiber. Next, a flame-retardant treatment process is carried out to convert the fiber bundle produced in the spinning process into a flame-retardant fiber in an oxidizing atmosphere at 200 to 300°C, preferably 230 to 270°C. When further obtaining carbon fiber, a carbonization process is carried out to carbonize the flame-retardant fiber in an inert atmosphere at 300 to 2000°C, preferably 300 to 1300°C. The carbonization process may be carried out subsequent to the flame-retardant treatment process.

As described above, the method for producing the nonwoven fabric of this embodiment first involves a step of adhering the treatment agent of the first embodiment to the carbon fibers. The method for adhering the treatment agent to the carbon fibers can be any known method. For example, methods that are generally used industrially, such as the immersion oiling method, roller immersion method, roller contact method, spray method, papermaking method, and guide oiling method using a metering pump, can be used.

The form in which the treatment agent of the first embodiment is applied to the fiber includes, for example, an organic solvent solution, an aqueous liquid, and the like. The treatment agent is preferably applied to the carbon fiber in the form of an aqueous emulsion liquid. The length of the fiber to which the treatment agent is applied is not particularly limited, and examples thereof include short fibers generally called staples and long fibers generally called filaments. In addition, carbon fiber in which two or more different types of staples are mixed and spun may be used. Examples of synthetic fibers to be spun 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 spun is not particularly limited, but is preferably 10:90 to 90:10, and more preferably 20:80 to 80:20. In the case of spun, the treatment agent may be applied either before or after the carbon fiber and synthetic fiber are spun.

Then, the carbon fiber with the treatment agent attached can be obtained by drying the carbon fiber and removing the solvent, such as water, contained in the solution of the treatment agent. For the drying process, for example, a method using hot air, a hot plate, a roller, or various infrared heaters as a heat medium can be used.

Next, a web forming process is carried out. In the web forming process, the carbon fibers to which the treatment agent is applied are carded to produce a web made of nonwoven fabric. Carding can be carried out using a known carding machine. Examples include flat cards, combination cards, and roller cards.

The effects of the treatment agent and nonwoven fabric of this embodiment will be described.
(1) The treatment agent of this embodiment is constituted by blending an epoxy compound (A). Therefore, when passing through a carding machine, it is possible to reduce breakage of the carbon fiber to which the treatment agent is applied. In addition, it is possible to improve the strength of the nonwoven fabric obtained from the carbon fiber to which the treatment agent is applied.

(2) When the treating agent contains a predetermined amount of the nonionic surfactant (B) or the ester compound (C), the strength of the nonwoven fabric obtained from the carbon fibers to which the treating agent has been applied can be further improved.
The above embodiment may be modified as follows: The above embodiment and the following modifications may be combined with each other to the extent that no technical contradiction occurs.

- The treatment agent of the above embodiment may further contain components that are typically used in treatment agents, such as stabilizers for maintaining the quality of the treatment agent, antistatic agents, binders, antioxidants, and ultraviolet absorbers, within the scope that does not impair the effects of the present invention.

The following examples are provided to more specifically illustrate the configuration and effects of the present invention, but the present invention is not limited to these examples. In the following examples and comparative examples, parts means parts by mass, and % means % by mass.

Test section 1 (preparation of treatment agent)
As shown in Table 1, the treatment agent of each example was prepared by gradually adding water or an organic solvent to an epoxy compound (A), a nonionic surfactant (B), an ester compound (C), and other components (D) while stirring so that the solid content concentration became 30%.

Test Section 2 (Manufacturing of Carbon Fiber Nonwoven Fabric)
Using the treatment agent prepared in Test Section 1, a carbon fiber nonwoven fabric was produced.
The aqueous or organic solvent solution of each treatment agent thus prepared was further diluted with water to obtain a 1 to 4% aqueous solution of each treatment agent. This aqueous solution was applied to short carbon fibers having a fiber length of 45 mm by a spray oiling method. The fibers were then dried in a hot air dryer at 105°C for 60 minutes to obtain treated short carbon fibers having the treatment agent applied thereto. The treated short carbon fibers thus obtained were conditioned overnight in an atmosphere of 25°C and 65% RH and then subjected to evaluation. In addition, in Example 47 and the like, the synthetic fibers shown in the table were blended in a predetermined ratio.

10 kg of the treated short carbon fibers obtained above were subjected to a carding process with a two-ridge condenser. The carding process was carried out under the following conditions: 25°C x 65% RH, spinning speed = 18.0 m/min, spinning radius = 1 g/m, and number of kneading = 30 times/inch. As a result, a carbon fiber nonwoven fabric was obtained as a web.

Test category 3 (carbon fiber breakage prevention)
The degree of folding of the carbon fibers was evaluated by measuring the percentage of the length of the carbon fibers before and after carding. After passing short fibers of 50 mm length through a card, the lengths of the short fibers were measured for n=50 fibers and the average value was calculated. The value was calculated by (average length after carding/average length before carding)×100 and evaluated according to the following criteria.

・Evaluation criteria for carbon fiber breakage prevention ◎ (Good): 90% or more ○ (Acceptable): 70% or more, less than 90% × (Not acceptable): Less than 70% Test category 4 (Strength of manufactured web)
The obtained web was held and pulled, and the ratio at which it broke was measured to evaluate the strength of the produced web. The produced web was stretched for 1 minute using a tensile strength and elongation tester at a grip length of 10 cm and a pulling speed of 10 cm/min, and it was confirmed whether the web broke during that time. Evaluation was made according to the following criteria.

Evaluation criteria for strength of produced web: Excellent (excellent): when the web is not broken during stretching, Good (good): when the web is broken between 50 and 60 seconds during stretching, Fair (fair): when the web is broken between 40 and 50 seconds during stretching, Poor (unfair): when the web is broken in less than 40 seconds during stretching. As is clear from the evaluation results of each example and each comparative example in the above table, the treatment agent of the present invention can reduce breakage of carbon fiber to which the treatment agent is applied when passing through a card. Also, the strength of the web obtained from carbon fiber to which the treatment agent is applied can be improved.

Claims (9)

A treatment agent for producing a carbon fiber-containing nonwoven fabric, comprising an epoxy compound (A) , a nonionic surfactant (B) , and an ester compound (C) , characterized in that the content of the epoxy compound (A) in a non-volatile matter of the treatment agent is 5% by mass or more and 60% by mass or less, the content of the ester compound (C) is 5 to 50% by mass, and the epoxy compound (A) has at least one compound selected from bisphenol A, bisphenol F, and diaminodiphenylmethane as a main skeleton.
Ester compound (C): An ester compound consisting of a monohydric aliphatic alcohol and a monobasic carboxylic acid. A treatment agent for producing a carbon fiber-containing nonwoven fabric, comprising an epoxy compound (A) , a nonionic surfactant (B) , and an ester compound (C) , characterized in that the content of the nonionic surfactant (B) in a non-volatile matter of the treatment agent is 30 mass % or more and 60 mass % or less , the content of the ester compound (C) is 5 to 40 mass %, and the epoxy compound (A) has at least one member selected from bisphenol A and bisphenol F as a main skeleton.
Ester compound (C): An ester compound consisting of a monohydric aliphatic alcohol and a monobasic carboxylic acid. The treatment agent for producing a carbon fiber-containing nonwoven fabric according to claim 1, wherein the epoxy compound (A) has at least one selected from a bisphenol A skeleton and a bisphenol F skeleton. The treatment agent for producing a carbon fiber-containing nonwoven fabric according to claim 2, wherein the content of the epoxy compound (A) in the non-volatile content of the treatment agent is 5 to 60 mass %. The treatment agent for producing carbon fiber-containing nonwoven fabric according to claim 1, wherein the content of the nonionic surfactant (B) in the nonvolatile content of the treatment agent is 5 to 60 mass %. 2. The treatment agent for producing a carbon fiber-containing nonwoven fabric according to claim 1 , wherein the treatment agent contains the epoxy compound (A) in an amount of 5 to 90 mass%, the nonionic surfactant (B) in an amount of 5 to 60 mass%, and the ester compound (C) in an amount of 5 to 50 mass%, assuming that the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100 mass% . 3. The treatment agent for producing a carbon fiber-containing nonwoven fabric according to claim 2, wherein the treatment agent contains the epoxy compound (A) in an amount of 5 to 60 mass%, the nonionic surfactant (B) in an amount of 30 to 60 mass%, and the ester compound (C) in an amount of 5 to 50 mass%, assuming that the total content of the epoxy compound (A), the nonionic surfactant (B), and the ester compound (C) is 100 mass% . A carbon fiber-containing nonwoven fabric having the treating agent according to any one of claims 1 to 7 adhered thereto. A method for producing a carbon fiber-containing nonwoven fabric, comprising a step of adhering the treating agent according to any one of claims 1 to 7 to short carbon fibers.