JPH1112855A - Carbon fiber precursor acrylic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carbon fiber precursor acrylic fiber without any fusion among single fibers and without existing fuzz, remarkably improved in process passableness in a flameproofing step and suitable for producing the carbon fibers excellent in quality and physical properties by applying a prescribed amount of a specific mixture thereto. SOLUTION: A mixture composed of (A) an amino-modified silicone represented by formula I R is a 1-20C alkyl or a 6-20C aryl; X is Q-(NH-Q')p - NH2 [Q and Q' are each a 1-10C bivalent hydrocarbon; (p) is 0-2]; Y is X, R, a 1-5C alkoxy or hydroxyl group; (m) is 10-10,000; (m) is 0-100} such as a compound represented by formula II with (B) 0.01-20 wt.% (based on the component A) of an aromatic amino-group-containing organopolysiloxane and (C) 5-100 wt.% (based on the component A) of a nonionic surfactant having 6-16 HLB such as a polyoxyethylene alkyl ether or a polyoxyethylene alkylphenyl ether in an amount of 0.1-3 wt.% based on the weight of an acrylic fiber is applied thereto to thereby afford a precursor acrylic fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber precursor acrylic fiber which is suitable for producing carbon fiber having excellent quality and physical properties and has improved processability in producing carbon fiber.

[0002]

2. Description of the Related Art Conventionally, acrylic fibers have been widely used as precursors for producing carbon fibers. 20 acrylic fibers
It is converted to oxidized fiber by heat treatment in an oxidizing atmosphere at 0 to 400 ° C., followed by at least 1000
A method of carbonizing in an inert atmosphere at a temperature of ° C. is generally used as a method for producing carbon fibers. The carbon fiber thus obtained is widely used as a suitable reinforcing fiber such as a fiber-reinforced resin composite material due to its excellent physical properties.

On the other hand, in the above-mentioned method for producing carbon fibers, fusion between single fibers occurs in a flame-proofing step of converting carbon fiber precursor acrylic fibers into flame-resistant fibers, resulting in non-uniform sintering, fluffing and the like. Problems such as thread breakage occur. It is known that in order to avoid this fusion, it is important to select an oil agent to be applied to the carbon fiber precursor acrylic fiber before flame resistance, and many oil agents have been studied.

[0004] For example, silicone oils are often used as oils for carbon fiber precursors because they have high heat resistance and effectively suppress fusion.
No. 40821).

[0005] However, the oil agent for the carbon fiber precursor acrylic fiber is required not only to be subjected to the flame-proofing step but also to have no fusing to the carbon fiber precursor acrylic fiber itself and substantially not to generate fluff. . That is, in the spinning step of the carbon fiber precursor acrylic fiber, the yarn discharged from the spinning nozzle is coagulated in a coagulation bath, and washed, or stretched. In the drying step of densification, it is required to prevent fusion between the single fibers, form a uniform and dense fiber structure, and provide a fiber having good processability. However, known silicone oils tend to gel during heat treatment, and in the drying step, the gelled silicone oils may induce fluff and breakage of yarn. Therefore, it is necessary that the oil agent for carbon fiber precursor acrylic fiber has high heat resistance and does not easily gel.

In addition, in the oxidization process, silicon oxide and the like, which are decomposition products of the silicone oil, are generated and are deposited on the oxidization furnace wall and the exhaust gas treatment line, thereby lowering the operability. It is also required that the amount of decomposed oils be small.

However, there has been no report on a carbon fiber precursor acrylic fiber which satisfies all of the above performances.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon fiber precursor acrylic fiber which has no fusion between single yarns, has substantially no fluff, and has a fluff of precursor fiber in a flame-proofing step. Provided is a carbon fiber precursor acrylic fiber in which yarn breakage and fusion between single yarns are effectively suppressed, and the processability in the flame-proofing step is remarkably improved by reducing scattering of silicone decomposition products in the flame-proofing step. It is in.

[0009]

Means for Solving the Problems The present inventors have added an antioxidant and a specific surfactant to a specific amino-modified silicone, and allowed the acrylic fiber to give a specific amount of the amino-modified silicone mixture. The gelling temperature of the carbon fiber precursor is remarkably improved, and there is no fusion between single yarns as a carbon fiber precursor acrylic fiber, and there is substantially no fluff. It has been found that the process fusion in the flame-proofing step is remarkably improved by effectively suppressing the inter-fusion and reducing the scattering of the silicone decomposed product in the flame-proofing step, and completed the present invention. That is, the gist of the present invention resides in a carbon fiber precursor acrylic fiber provided with a mixture of the following components (A) to (C) in an amount of 0.1 to 3% by weight based on the fiber weight. (A) an amino-modified silicone represented by the following general formula (1),

[0010]

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(Wherein R is the same or different and has 1 to 2 carbon atoms)
0 alkyl group or an aryl group having 6 to 20 carbon atoms, X is 'represented by _p -NH _2, Q and Q formula -Q- (NH-Q)' is from 1 to 10 carbon atoms of the same or different Y is X, R, an alkoxy group having 1 to 5 carbon atoms or a hydroxyl group, and p is any one of 0, 1 and 2. Also, 10 ≦ m ≦ 10000 and 0 ≦ n ≦ 100. (B) Antioxidant 0.01 to 20% by weight of component (A) (C) Nonionic surfactant of HLB 6 to 16 16 to 100% by weight of component (A)

The component (C) is preferably polyoxyethylene alkyl ether and / or polyoxyethylene alkyl phenyl ether.

The component (B) is preferably an aromatic amino group-containing organopolysiloxane, and the aromatic amino group-containing organopolysiloxane represented by the following general formula (2) is more preferable. It is listed as.

[0014]

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(Wherein R ′ is the same or different and has 1 to 1 carbon atoms)
20 is an alkyl group or an aryl group having 6 to 20 carbon atoms, and Z is R ′, —O—Ph—NH—Ph, —O—Ph—
NH-Ph-NH-Ph, a monovalent aromatic amino group selected from the compounds represented by the following formulas (3) and (4). Further, q and r are 1 ≦ q ≦ 50 and 0 ≦ r
≦ 10, but it is necessary to have at least one or more aromatic amino groups in the molecule. Therefore, when r = 0, at least one of Z in the formula is the above-mentioned monovalent aromatic amino group. . )

[0016]

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[0017]

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[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As the acrylic fiber used for the carbon fiber precursor acrylic fiber of the present invention, known acrylic fibers can be exemplified, and the composition thereof is not particularly limited, but acrylonitrile unit is 95% by weight or more and copolymerized with acrylonitrile. Acrylic fibers obtained by spinning an acrylonitrile-based polymer comprising 5% by weight or less of a possible vinyl-based monomer unit are preferred. Further, as the copolymerizable vinyl monomer, acrylic acid, methacrylic acid, itaconic acid, or an alkali metal salt or an ammonium salt thereof, which has an action of promoting a flame-resistant reaction, or a monomer group such as acrylamide is selected. It is preferable to use one or more monomers in order to promote the flame-resistant reaction. The method for producing such a fiber bundle is also not particularly limited, and known wet, dry, and dry-wet spinning methods are employed.

In the amino-modified silicone represented by the general formula (1) used as the component (A) in the present invention, R in the formula is the same or different and is an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. And specifically, methyl, ethyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, tetradecyl, octadecyl, phenyl, tolyl, naphthyl, etc. Alternatively, a monovalent hydrocarbon group in which part or all of the hydrogen atoms bonded to these carbon atoms are substituted with a halogen atom, a hydroxyl group, or the like may be used. Of these, a methyl group is preferred. Then, X is the formula -Q- 'is an amino group represented by _p -NH _2, Q and Q (NH-Q)' is a divalent hydrocarbon group having 1 to 10 carbon atoms of the same or different Specifically, methylene group, dimethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group and a part of these carbon atoms Examples include those substituted with another atom such as an oxygen atom and a sulfur atom, and those in which part or all of the hydrogen atoms of these carbon atoms are substituted with a halogen atom, a hydroxyl group, and the like. Of these, a dimethylene group or a trimethylene group is preferred. Y is any of the aforementioned X, R, an alkoxy group having 1 to 5 carbon atoms or a hydroxyl group,
Examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, a butoxy group and a propoxy group.
p is 0, 1 or 2; From the viewpoint of production, p is preferably 0 or 1. Also, 10 ≦ m ≦ 10000,
0 ≦ n ≦ 100, preferably 50 ≦ m ≦ 100
0, 0 ≦ n ≦ 10.

Specific examples of such an amino-modified silicone include compounds represented by the following formulas (5) to (15), but the present invention is not limited thereto.

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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The antioxidant of the component (B) in the present invention is used to suppress the thermal oxidative deterioration of the amino group, and comprises a hinder represented by the following formulas (16) and (17). Dophenols, PhNHPhNHPh, Ph
Examples include NHPh, aromatic amines represented by the following formulas (18) and (19), hindered phenol group-containing organopolysiloxanes, aromatic amino group-containing organopolysiloxanes, etc. An aromatic amino group-containing organopolysiloxane represented by 2). Here, Ph represents a phenyl group.

[0033]

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[0034]

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[0035]

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[0036]

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In the present invention, the amount of the component (B) to be added may be from 0.01 to 20 of the amino-modified silicone of the component (A).
% By weight. If it is less than 0.01% by weight, the effect of improving heat resistance is weak, and if it is added in excess of 20% by weight, the effect of improving heat resistance does not change, but rather the stability of the silicone emulsion deteriorates. % Is preferred,
More preferably, it is 0.1 to 4% by weight.

Next, HLB6 of the component (C) in the present invention is used.
The nonionic surfactants Nos. To 16 are surfactants for emulsifying and dispersing both components (A) and (B) in water.
When the HLB exceeds 16, the heat resistance of the obtained silicone emulsion becomes insufficient, and when the HLB is less than 6, the emulsion stability of the silicone emulsion deteriorates, so that the HLB is 6 to 16. Preferably, it is 10-14.

Specific examples of the nonionic surfactant (C) in the present invention include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and sorbitan fatty acid ester. Among them, polyoxyethylene alkyl phenyl ether and polyoxyethylene alkyl ether are preferred. This addition amount is 5 to 100% by weight of the amino-modified silicone of the component (A). If the amount is less than 5% by weight, the emulsification stability of the amino-modified silicone is deteriorated. If the amount exceeds 100% by weight, the properties of the amino-modified silicone may be impaired.
It is preferably 100% by weight, more preferably 1% by weight.
0 to 50% by weight.

It should be noted that an antistatic agent, a penetrating agent, a thickener, an antifoaming agent, a preservative, and the like may be appropriately added to the silicone emulsion composition comprising these components as various additives to improve the properties thereof. Absent.

The amount of the oil agent for the heat-resistant amino-modified silicone mixture carbon fiber precursor comprising the above components (A) to (C) is 0.1 to 3% by weight, preferably 0.3 to 3% by weight, based on the fiber.
The amount is preferably 1.5% by weight, and if the amount is less than 0.1% by weight, it is not possible to suppress fluff, breakage and fusion between single fibers of the precursor fiber in the oxidization-resistant step, which is the object of the present invention. If the amount exceeds 3% by weight, the amount of decomposition products of the silicone-based oil agent in the flame-proofing step increases, which is not preferable.

[0042]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention.

The degree of gelation, the weight retention, the number of fusions, the passability of the oil before the oxidizing step, the state of dispersion of the silicone oil decomposition product, and the strand strength of the oil were evaluated by the following methods.

[Measurement and evaluation method of heat resistance (gelling degree)]
2.0 g of the oil emulsion was precisely weighed in an aluminum Petri dish (diameter 60 mm, depth 10 mm), pre-dried at 105 ° C. for 1 hour, and heated at 150 ° C. for 24 hours to determine the insoluble content in chloroform of the residue. The degree of gelation was calculated and the heat resistance was evaluated. The smaller the gelation degree, the better the heat resistance and the better the processability in the drying step after the oil emulsion is attached, meaning less fuzz and thread breakage induced by the gelled silicone oil. I do.

[Measurement and Evaluation Method of Decomposition and Scattering Behavior (Weight Retention)] Aluminum Petri dish (60 mm in diameter, 10 m in depth)
In m), 2.0 g of the oil agent emulsion was precisely weighed, preliminarily dried at 105 ° C. for 1 hour, and the weight retention rate of the residue after heating at 250 ° C. for 1 hour was calculated to evaluate the dispersion and scattering behavior. The larger the weight retention ratio, the less the resin is liable to be decomposed and scattered, which means that the amount of the silicone oil agent dispersion in the flameproofing step is small.

[Method of Measuring and Evaluating Fusion between Single Fibers (Number of Fusions)] A carbon fiber tow was cut into a length of 3 mm, dispersed in acetone, and stirred with a magnetic stirrer for 10 minutes. And the number of fusions were counted, and the number of fusions per 100 fibers was calculated. ：: Number of fusions (pieces / 100 pieces) ≦ 1 ×: 1 <Number of fusions (pieces / 100 pieces)

[Passability of the Pre-Oxidation Process] The number of windings of the carbon fiber precursor acrylic fiber on a roll or the like at the stage of the carbon fiber precursor acrylic fiber before the oxidization resistance when continuously sampling for one week using the carbon fiber precursor acrylic fiber The amount of fluff and thread breakage at the stage of the carbon fiber precursor acrylic fiber was evaluated. ：: Number of windings (times / day) ≦ 1 Δ: 1 <Number of windings (times / day) ≦ 10 ×: 10 <Number of windings (times / day)

[Dispersion of Silicone Oil Decomposed Product] The amount of decomposed silicone oil agent in the oxidizing furnace was evaluated based on the frequency of cleaning of the oxidizing furnace when carbon fibers were continuously sampled for one week. ○: Number of cleaning times (times / week) ≤ 1 ×: <Number of winding times (times / week)

[Measurement and Evaluation Method of Carbon Fiber Physical Properties (Strand Strength)] This is a value measured according to the epoxy resin-impregnated strand method specified in JIS-R-7601. (Note that the number of measurements was ten, and the physical properties were indicated by the average.)

Preparation Example 1 3 kg of an amino-modified silicone represented by the following formula (20):

[0051]

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As an antioxidant, 10 g of an aromatic amino group-containing organopolysiloxane represented by the following formula (21):

[0053]

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Polyoxyethylene lauryl ether [EO: 5 mol, HLB: 10.8] 600 as emulsifier
g of water and 16.4 g of water were emulsified with a homomixer, and further subjected to secondary emulsification at 300 kg / cm ² with a high-pressure homogenizer to obtain an oil emulsion. The heat resistance and decomposition and scattering behavior of this oil agent were measured, and the results are shown in Table 1.

(Adjustment Example 2) The equation (2) used in Adjustment Example 1 was used.
A mixture of 3 kg of the amino-modified silicone shown in 0), 600 g of polyoxyethylene lauryl ether [EO: 5 mol, HLB: 10.8] as an emulsifier, and 16.4 g of water was emulsified with a homomixer in the same manner as in Preparation Example 1. Then, secondary emulsification was performed with a high-pressure homogenizer to obtain an oil emulsion. The heat resistance and decomposition and scattering behavior of this oil agent were measured, and the results are shown in Table 1.

(Preparation Example 3) 3 kg of an amino-modified silicone represented by the following formula (22):

[0057]

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Polyoxyethylene lauryl ether [EO: 5 mol, HLB: 10.8] 600 as emulsifier
g and water (16.4 g) were emulsified with a homomixer in the same manner as in Preparation Example 1, and then subjected to secondary emulsification with a high-pressure homogenizer to obtain an oil emulsion. The heat resistance and decomposition and scattering behavior of this oil agent were measured, and the results are shown in Table 1.

Example 1 An acrylonitrile copolymer (acrylonitrile unit / methacrylic acid unit / acrylamide unit = 97.1 / 0.9 / 2.0 (% by weight)) was dissolved in dimethylacetamide to give a polymer concentration of 21. A spinning solution having a viscosity of 500 poise at 60% by weight and a viscosity of 500 poise was prepared in a coagulation bath filled with a 69% by weight aqueous solution of dimethylacetamide at 35 ° C, having a pore diameter of 0.15 mmφ and a number of holes of 150
No. 0 was once discharged into the air through a spinneret and passed through a space of about 5 mm to obtain a coagulated yarn. The coagulated yarn was desolvated in a washing tank and stretched 3.5 times to obtain a water-swelled acrylic fiber.

The acrylic fiber in the water-swelled state was led to an oil bath filled with the oil agent emulsion prepared in Preparation Example 1, and the emulsion was applied. The emulsion was dried and densified with a heating roll having a surface temperature of 130 ° C. The film was stretched 2.0 times between heating rolls at a temperature of ° C to obtain a precursor acrylic fiber. This precursor acrylic fiber had a single yarn fineness of 1.1 denier, a tensile strength of 7 g / denier, an elongation of 12.5%, and the amount of the oil agent applied to the fiber was 1.0% by weight. The amount of oil applied to the fibers was determined by adding a certain amount of oil per unit time to the oil bath, and operating for a sufficiently long time to reach the equilibrium state. Was taken as the applied amount.

This precursor acrylic fiber is used in the range of 230 to 270.
The mixture was passed through an oxidization furnace having a temperature gradient of 60 ° C. for 60 minutes, and further fired in a carbonization furnace having a temperature gradient of 300 to 1300 ° C. in a nitrogen atmosphere to obtain carbon fibers. Table 2 shows the fusion number and strand strength of the obtained carbon fibers, the passability of the process before the oxidization process, and the state of scattering of the silicone decomposed product in the oxidization process.

Comparative Example 1 A precursor acrylic fiber was obtained in the same manner as in Example 1, except that the oil emulsion prepared in Preparation Example 2 was used instead of the oil emulsion prepared in Preparation Example 1. This precursor acrylic fiber had a single yarn fineness of 1.1 denier, a tensile strength of 6.8 g / denier and an elongation of 11.8%, and the amount of the oil agent applied to the fiber was 1.0% by weight.

The precursor acrylic fiber was fired in the same manner as in Example 1 to obtain a carbon fiber. The fusion number and strand strength of the obtained carbon fiber, passability before the oxidization process,
Table 2 shows the state of scattering of the silicone decomposed product in the oxidization process.

Comparative Example 2 A precursor acrylic fiber was obtained in the same manner as in Example 1, except that the oil emulsion prepared in Preparation Example 3 was used instead of the oil emulsion prepared in Preparation Example 1. This precursor acrylic fiber had a single yarn fineness of 1.1 denier, a tensile strength of 6.7 g / denier and an elongation of 11.5%, and the amount of the oil agent applied to the fiber was 1.0% by weight.

The precursor acrylic fiber was fired in the same manner as in Example 1 to obtain a carbon fiber. The fusion number and strand strength of the obtained carbon fiber, passability before the oxidization process,
Table 2 shows the state of scattering of the silicone decomposed product in the oxidization process.

Example 2 The same spinning dope as in Example 1 was prepared and placed in a coagulation bath filled with a 69% by weight aqueous solution of dimethylacetamide at 35 ° C., having a pore diameter of 0.075 mmφ and a pore number of 12
000 from a spinneret with a draft ratio of 0.8 to obtain a coagulated yarn. The coagulated yarn was desolvated in a washing tank and stretched 5 times to obtain a water-swelled acrylic fiber.

The water-swelled acrylic fiber was introduced into an oil bath filled with the emulsion prepared in Preparation Example 1, and the emulsion was applied. The emulsion was dried and densified with a heating roll having a surface temperature of 130 ° C., and further, a surface temperature of 170 ° C. Was drawn 1.7 times between heating rolls to obtain a precursor acrylic fiber. This precursor acrylic fiber had a single yarn fineness of 1.1 denier, a tensile strength of 7 g / denier, an elongation of 10.5%, and the applied amount of the oil agent to the fiber was 1.0% by weight.

The precursor acrylic fiber was fired in the same manner as in Example 1 to obtain a carbon fiber. The fusion number and strand strength of the obtained carbon fiber, passability before the oxidization process,
Table 2 shows the state of scattering of the silicone decomposed product in the oxidization process.

Comparative Example 3 A precursor acrylic fiber was obtained in the same manner as in Example 2, except that the immersion time of the acrylic fiber in a water-swelled state in an oil bath filled with an emulsion was changed. This precursor acrylic fiber had a single yarn fineness of 1.1 denier, a tensile strength of 6.7 g / denier, an elongation of 9.8%, and the amount of the oil agent applied to the fiber was 0.09% by weight.

This precursor acrylic fiber was fired in the same manner as in Example 1 to obtain a carbon fiber. The fusion number and strand strength of the obtained carbon fiber, passability before the oxidization process,
Table 2 shows the state of scattering of the silicone decomposed product in the oxidization process.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

The carbon fiber precursor acrylic fiber of the present invention has no fusion between single yarns, has substantially no fluff, and has fluff, breakage and single yarn of the precursor fiber in the flame-proofing step. The fusion is effectively suppressed, and the passage of the silicone decomposition product in the flame-proofing step is reduced to thereby significantly improve the processability in the flame-proofing step.

Claims (4)

[Claims] 1. A carbon fiber precursor acrylic fiber provided with a mixture comprising the following components (A) to (C) in an amount of 0.1 to 3% by weight based on the fiber weight. (A) an amino-modified silicone represented by the following general formula (1): (Wherein, R is the same or different alkyl group having 1 to 20 carbon atoms or aryl group having 6 to 20 carbon atoms, and X is a general formula -Q-
'Represented by _p -NH _2, Q and Q (NH-Q)' is a divalent hydrocarbon group having 1 to 10 carbon atoms the same or different, Y
Is X, R, an alkoxy group having 1 to 5 carbon atoms or a hydroxyl group, and p is any of 0, 1 or 2. Also, 10 ≦ m ≦ 10000 and 0 ≦ n ≦ 100. (B) Antioxidant 0.01 to 20% by weight of component (A) (C) Nonionic surfactant of HLB 6 to 16 16 to 100% by weight of component (A) 2. The carbon fiber precursor acrylic fiber according to claim 1, wherein the component (C) is polyoxyethylene alkyl ether and / or polyoxyethylene alkyl phenyl ether. 3. The carbon fiber precursor acrylic fiber according to claim 1, wherein the component (B) is an aromatic amino group-containing organopolysiloxane. 4. The carbon fiber precursor acrylic fiber according to claim 1, wherein the component (B) is an aromatic amino group-containing organopolysiloxane represented by the following general formula (2). Embedded image (Wherein R ′ is the same or different alkyl group having 1 to 20 carbon atoms or aryl group having 6 to 20 carbon atoms, and Z is R ′,
-O-Ph-NH-Ph, -O-Ph-NH-Ph-N
H-Ph, any one of monovalent aromatic amino groups selected from the compounds represented by the following formulas (3) and (4).
Further, q and r are 1 ≦ q ≦ 50 and 0 ≦ r ≦ 10, and since it is necessary to have at least one or more aromatic amino groups in the molecule, when r = 0, Z in the formula Is at least one of the above-mentioned monovalent aromatic amino groups. Here, Ph represents a phenyl group. ) Embedded image